Direct inhibitory effect of erythromycin on human alimentary tract smooth muscle

BACKGROUND: Erythromycin was found to stimulate motor activity in the upper gastrointestinal tract. However, in several smooth muscle preparations, it also elicited an inhibitory effect. Our aim was to study the effect of erythromycin in various human alimentary tract smooth muscles. METHODS: Using force measurements, we assessed the effect of erythromycin on electrically and chemically evoked contractions of isolated muscle strips of human gallbladder, small intestine, and colon. RESULTS: The muscarinic receptor agonist carbachol evoked contraction in gallbladder, ileum, and colonic smooth muscle that were reduced by erythromycin at 10(-4) M to 72% +/- 24%, 77% +/- 22%, and 76% +/- 22% of control values, respectively. Erythromycin did not affect contractions evoked by noncholinergic agents. Erythromycin's inhibitory effects were not altered by nerve blockade, indicating a direct muscle effect. Eryrthromycin also reduced contractions evoked by electrical stimulation at frequencies of 5, 10, and 20 Hz in the human gallbladder, ileum, and colon preparations. These contractions were reduced by erythromycin in a reversible and dose-dependent manner. CONCLUSIONS: Erythromycin antagonized direct cholinergic effects on various smooth muscles from the human alimentary tract in a concentration-dependent manner.     

Decreased gallbladder response in leptin-deficient obese mice

Obesity is a major risk factor for gallstone formation, but the pathogenesis of this phenomenon remains unclear. Human data on gallbladder emptying are conflicting, and no animal data exist on the effect of obesity on gallbladder motility. Leptin, a hormone produced by adipocytes, is known to have central effects on neuropeptide Y and cholecystokinin, but the influence of leptin on the biliary effects of these hormones is unknown. Therefore we tested the hypothesis that leptin-deficient C57BL/6J-lep^ob obese mice would have decreased gallbladder responses to excitatory stimuli. Twelve-week-old lean control (C57BL/6J) (n = 22) and C57BL/6J-lep^ob obese (n = 20) female mice were fed a nonlithogenic diet. The mice were fasted overnight and underwent cholecystectomy. Whole gallbladders were placed in 3 ml muscle baths. After optimal length was determined with acetylcholine (10^-5 mol/L, responses to increasing doses of neuropeptide Y (10^-8 to 10^-6 mol/L) and cholecystokinin-8 (10^-10 to 10^-7 mol/L) were measured. Student’s t test and two-way analysis of variance were used where appropriate. Results were expressed as Newtons per cross-sectional area. The lean control mice had significantly greater excitatory responses to acetylcholine than the obese mice (0.37 ± 0.05 vs. 0.16 ± 0.02, P < 0.01). The gallbladder responses were also greater when mice were treated with neuropeptide Y (10^-8 mol/L: 0.00 ± 0.00 vs. 0.00 ± 0.00, NS; 10^-7 mol/L: 0.12 ± 0.02 vs. 0.05 ± 0.01, P < 0.01; 10^-6 mol/L: 0.26 ± 0.08 vs. 0.06 ± 0.01, P < 0.01) and cholecystokinin (10^-10 mol/L: 0.27 ± 0.04 vs. 0.13 ± 0.02, P < 0.01; 10^-9 mol/L: 0.59 ± 0.08 vs. 0.27 ± 0.04, P < 0.01; 10^-8 mol/L: 0.80 ± 0.11 vs. 0.37 ± 0.05, P < 0.01; 10^-7 mol/L: 0.86 ± 0.11 vs. 0.44 ± 0.06, P < 0.01). These data suggest that genetically obese, leptin-deficient mice have decreased responses to acetylcholine, neuropeptide Y, and cholecystokinin. We conclude that decreased gallbladder motility contributes to the increased incidence of gallstones associated with obesity. Presented at the Forty-Second Annual Meeting of The Society for Surgery of the Alimentary Tract, Atlanta, Georgia, May 20–23, 2001 (oral presentation). Supported by grant RO1-DK442 79–07 from the National Institutes of Health.     

Mechanisms of impaired gallbladder contractile response in chronic acalculous cholecystitis

The mechanisms involved in the impaired gallbladder contractile response in chronic acalculous cholecystitis are unknown. To determine the mechanisms that may lead to impaired gallbladder emptying in chronic acalculous cholecystitis, gallbladder specimens removed during hepatic resection (controls) and after cholecystectomy for chronic acalculous cholecystitis were attached to force transducers and placed in tissue baths with oxygenated Krebs solution. Electrical field stimulation (EFS) (1 to 10 Hz, 0.1 msec, 70 V) or the contractile agonists, CCK-8 (10^-9 to 10^-5) or K⁺ (80 mmol/L), were placed separately in the tissue baths and changes in tension were determined. Patients with chronic acalculous cholecystitis had a mean gallbladder ejection fraction of 12% ± 4%. Pathologic examination of all gallbladders removed for chronic acalculous cholecystitis revealed chronic cholecystitis. Spontaneous contractile activity was present in gallbladder strips in 83% of control specimens but only 29% of gallbladder strips from patients with chronic acalculous cholecystitis (P < 0.05 vs. controls). CCK-8 contractions were decreased by 54% and EFS-stimulated contractions were decreased by 50% in the presence of chronic acalculous cholecystitis (P < 0.05 vs. controls). K⁺-induced contractions were similar between control and chronic acalculous cholecystitis gallbladder strips. The impaired gallbladder emptying in chronic acalculous cholecystitis appears to be due to diminished spontaneous contractile activity and decreased contractile responsiveness to both CCK and EFS. Presented at the Forty-Second Annual Meeting of The Society for Surgery of the Alimentary Tract, Atlanta, Georgia, May 20–23, 2001 (poster presentation). Supported by the Veterans Administration Research Service and National Institutes of Health training grant HLO 7485-19.     

Nonobese diabetic mice have diminished gallbladder motility and shortened crystal observation time

Diabetes and obesity are strongly associated and are risk factors for cholesterol gallstone disease. Leptinde ficient and leptin-resistant diabetic obese mice have enlarged, hypomotile gallbladders. In addition, bile from gallbladders of leptin-deficient mice has enhanced cholesterol crystal formation, whereas bile from gallbladders of leptin-resistant mice has delayed crystal observation time. To determine the effect of diabetes alone, we hypothesized that leptin-normal, nonobese diabetic (NOD) mice would have reduced biliary motility and rapid crystal formation. Twenty control and 9 prediabetic and 11 diabetic NOD, 12- to 26-week-old mice underwent glucose measurement and cholecystectomy for muscle bath stimulation with neurotransmitters. An additional group of 200 control and 78 NOD 12-week-old mice underwent microscopic bile examination for cholesterol crystal formation. Compared with control mice, prediabetic NOD mice had similar glucose levels and gallbladder volumes. Diabetic NOD mice had higher sugar levels and larger gallbladder volumes (P < 0.001) than control mice. Prediabetic NOD gallbladders had less contractility (P < 0.01) than control gallbladders, and contractility worsened (P < 0.01) in diabeticNODmice.NODmice formed cholesterol crystals earlier than did control mice (P<0.05). Nonobese diabetic NOD mice have (1) decreased gallbladder contraction to neurotransmitters, which worsens with development of diabetes, and (2) rapid crystal formation. We conclude that diabetes alone alters gallbladder motility and cholesterol crystal formation. Presented at Digestive Disease Week, 2004 SSAT Plenary Session, and Residents’ Conference, New Orleans, Louisiana, May 15–21, 2004 (oral presentation). This work was supported by National Institutes of Health grant R01-DK44279.     

Regulation of amino acid arginine transport by lipopolysaccharide and nitric oxide in intestinal epithelial IEC-6 cells

As a precursor for nitric oxide (NO) synthesis and an immune-enhancing nutrient, amino acid L-arginine plays a critical role in maintaining intestine mucosal integrity and immune functions in sepsis. However, the relationship between intestinal arginine transport and NO synthesis in sepsis remains unclear. In the present study, we investigated the effects of lipopolysaccharide (LPS) and NO on the arginine transport in cultured rat intestinal epithelial IEC-6 cell. Near-confluent IEC-6 cells were incubated with LPS (0-50 μg/ml) in serum-free Dulbecco’s modified Eagles’s medium, in the presence and absence of the NO donor sodium nitroprusside (SNP, 0–500 μmol/L) and the inducible nitric oxide synthase (iNOS) inhibitor N-ω-nitro-L-arginine (NNA, 0–1000 μmol/L) for various periods of time (0-48 hours). Arginine transport activity, arginine transporter CAT1 mRNA and protein levels were measured with transport assay, Northern blot analysis, and Western blot analysis, respectfully. LPS increased arginine transport activity in a time- and dose-dependent fashion. Prolonged incubation of LPS (24 hours, 25 μg/ml) resulted in a 3-fold increase of arginine transport activity (control: 28 ±5; LPS: 92 ±20 pmol/mg/ min, P < 0.05), with the System y⁺ as the predominant arginine transport system, and a 2-fold increase of System y⁺ CAT1 mRNA and transporter protein levels (P < 0.05). LPS increased the arginine transport System y⁺ maximal velocity (V_max, control: 1484 ±180; LPS: 2800 ±230 pmol/mg/min, P<0.05) without affecting the transport affinity (K_m, control: 76 ±8; LPS: 84 ±14 μmol/L, p = NS). The LPSinduced arginine transport activity was blocked by sodium nitroprusside (SNP) (control: 25 ±6; LPS: 97 ±26*; SNP: 22 ±0.4⁺; LPS+SNP: 33 ±10.3⁺ pmole/mg/min, *P < 0.01 and ⁺p = NS, compared with control). In contrary, the LPS-induced arginine transport activity was further augmented by NNA (control: 18 ±3.2; LPS: 59 ±2.7*; NNA: 26.3 ±5.8; LPS + NNA: 127 ±18⁺ pmol/mg/min; *P < 0.01 compared with control and ⁺P < 0.01 compared with control or LPS). LPS-stimulates arginine transport activity in IEC-6 cells via a mechanism that involves increase of transport System y⁺ mRNA levels and transporter protein levels. The LPS-stimulated arginine transport activity is regulated by the availability of nitric oxide. Presented at the Forty-Sixth Annual Meeting of The Society for Surgery of the Alimentary Tract, Chicago, Illinois, May 14–18, 2005 (oral presentation). This work was supported in part by The Society for Surgery of Alimentary Tract Career Development Award (M.P.) and National Institute of Diabetes and Digestive and Kidney Disease Grant DK-62165 (M.P.).     

The effect of erythromycin on bile excretion and proximal small bowel motility following divided gastric bypass surgery: a prospective randomized placebo-controlled trial

Background: No conclusive data exists supporting the use of any prokinetic agent in the postoperative setting. The study was designed to examine the effect of erythromycin on small bowel motility in a placebo-controlled trial of post gastric bypass patients utilizing a standardized nuclear medicine test. Methods: A consecutive series of 21 patients undergoing elective gastric bypass surgery for morbid obesity between September 1999 and March 2001 were enrolled in this prospective double-blind randomized controlled trial. Standard open, divided gastric bypass was performed. Patients were randomized to receive either erythromycin 250 mg I. V. (11 patients) or placebo (10 patients) every 8 hours. On postoperative day 2, a hepatic iminodiacetic acid (HIDA) scan was obtained. Tracer movement through the biliary tree and proximal small bowel was quantified and compared. Results:Tracer clearance from the liver and biliary tree was no different between groups from time of injection through 1 hour. Tracer material clearance from the duodenum into the jejunum was no different between the erythromycin and control groups at 1 hour, 37% ±13% and 37% ±22% respectively (P=0.95). At 4 hours, clearance was greater in the erythromycin group, 77%±6%, compared to control, 60%±20% (P =0.036). The rate of tracer change between hour 1 and 4 (slope) was steeper in the erythromycin group (P=0.048). Conclusions: Erythromycin increases intestinal transit in the postoperative setting.     

The oxalate level in ultrafiltrate fluid collected from a dialyzer is useful for estimating the plasma oxalate level in hemodialysis patients

Background Patients on chronic hemodialysis are likely to develop secondary hyperoxalemia. It is, however, difficult to measure plasma oxalate levels. To measure plasma oxalate levels, rapid plasma separation, deproteinization, and acidification are essential in preventing the formation of oxalate and the deposition of calcium oxalate within the test tube. The present study was undertaken to examine whether the oxalate level in dialyzer ultrafiltrate is potentially useful for estimating plasma oxalate levels. Methods In nine patients on chronic hemodialysis, the plasma, after deproteinization with a filter, and the ultrafiltrate from the dialyzer before hemodialysis were acidified to a pH level of less than 3, followed by the measurement of oxalate levels by ion chromatography. Also, oxalate levels were compared between acidified and non-acidified ultrafiltrates from the dialyzer. In the second part of the study, seven patients on chronic hemodialysis receiving erythropoietin therapy, in whom the ferritin level was more than 300 ng/ml and transferrin saturation was less than 25%, were intravenously administered ascorbic acid, 100 mg, three times a week, after each dialysis session to facilitate the utilization of stored iron. This treatment was continued until the serum ferritin level decreased to a level below 300 ng/ml (for 3 months, at a maximum). The oxalate level in the dialyzer ultrafiltrate after this treatment was compared with that before treatment. Results The mean ± SE oxalate level in the dialyzer ultrafiltrate was 45 ± 6 μmol/l, essentially equal to the plasma oxalate level (46 ± 7 μmol/l). The plasma oxalate level had a significant positive correlation with the dialyzer ultrafiltrate oxalate level (plasma oxalate level = 0.99 × dialyzer ultrafiltrate oxalate level + 1.5; r = 0.95; P < 0.0001). The oxalate level in the acidified ultrafiltrate (45 ± 6 μmol/l) did not differ significantly from that in the non-acidified ultrafiltrate (45 ± 6 μmol/l). The mean ± SE duration of ascorbic acid administration was 64 ± 13 days. The hemoglobin level remained unchanged at 9.6 ± 0.4 g/dl, whereas the serum iron level increased significantly, from 34 ± 2 μg/dl to 43 ± 4 μg/dl (P < 0.05), and serum ferritin levels decreased significantly, from 645 ± 219 ng/ml to 231 ± 30 ng/ml after the treatment (P < 0.05). The oxalate level in the acidified ultrafiltrate showed no significant change after ascorbic acid administration (31 ± 8 μmol/l vs 47 ± 7 μmol/l). Conclusions In patients on chronic hemodialysis, the oxalate level in acidified ultrafiltrate from the dialyzer was found to be useful for estimating the plasma level of non-protein-bound oxalate. When administering ascorbic acid to hemodialysis patients, the plasma oxalate level can be monitored using this method.     

Bariatric Surgery Cannot Prevent Tryptophan Depletion Due to Chronic Immune Activation in Morbidly Obese Patients

Background: Increased activity of the immuno-modulatory enzyme indoleamine-2,3-dioxygenase (IDO) during immune activation, results in tryptophan depletion. Tryptophan metabolic changes reduce serotonin production and cause mood disturbances, depression, and impaired satiety, ultimately leading to increased food intake and obesity. Bariatric surgery significantly diminishes immune mediators by substantial weight reduction. We examined IDO-mediated tryptophan-catabolism in morbidly obese patients compared to lean individuals. Methods: Serum concentrations of kynurenine and tryptophan, calculated kynurenine to tryptophan ratios (kyn trp-1) as an indirect estimate of IDO activity, and neopterin levels reflecting IFN-γ mediated immune activation, were assessed before and after bariatric surgery. The study population included 22 morbidly obese individuals and 20 normal-weight volunteers. Results: Median weight loss after 24.4±5.1 months was 40.6 kg resulting in a reduction of BMI from 44.1 kg/m² to 29.9 kg/m² (P<0.001). Preoperative kyn trp-1 in morbidly obese patients was significantly increased compared to the control group (41.6±20.1 mmol/mol vs 26.5±5.1 mmol/mol; P<0.001). Postoperative weight reduction did not lead to normalization of kyn trp-1 (37.9±14.0 mmol/mol). As a consequence, tryptophan levels were significantly lower in morbidly obese patients (pre-: 51.5±9.2 μmol L⁻¹ and postoperatively: 46.9±7.6 μmol L⁻¹) when compared with those of normal-weight controls (64.8±9.5 μmol L⁻¹; P<0.001). In addition, neopterin levels were elevated in the study population pre- and postoperatively compared to normal-weight volunteers (both P<0.001). Conclusions: Tryptophan depletion in morbidly obese patients is due to chronic immune activation and persists in spite of significant weight reduction following bariatric surgery. This might thereby be responsible for diminished serotonin functions, leading to unchanged satiety dysregulation and a reward-deficiency-syndrome.     

Effects of 8 Years of Treatment with Tibolone 2.5 mg Daily on Postmenopausal Bone Loss

The objective of this study was to assess the long-term effects of tibolone 2.5 mg daily (Livial¹; Organon) on bone mineral density in recently postmenopausal women. An 8-year, open, nonrandomized, prospective study was designed to compare the effects of tibolone 2.5 mg daily (n= 59) with an untreated control group (n= 51). The subjects of this study were 110 recently postmenopausal women (6–36 months since last menstrual period). The main outcome measures were bone mineral density of the spine and femur, measured by dual-energy X-ray absorptiometry, and assessment of biochemical markers of bone metabolism. After 8 years of tibolone use, the mean (± SEM) increase in bone mineral density compared with baseline was 4.1%± 0.8% (p<0.0001) in the spine and 4.6%± 1.8% (p= 0.015) in the femoral neck. Over the same period, bone mineral density in the control group decreased in the spine by –7.5%± 1.1%, (p<0.0001) and in the femur by –6.7%± 1.2% (p<0.0001). The bone resorption marker, calcium/creatinine ratio, decreased in the tibolone group but not in the control group. Serum bone formation markers decreased (alkaline phosphatase) or stayed approximately the same (osteocalcin) in the tibolone group. Adherence was high, with 58% (34 of 59) of the tibolone group continuing treatment for 8 years. We conclude that tibolone 2.5 mg daily prevents bone loss in the lumbar spine and femoral neck over 8 years and adherence to treatment is high. The greater bone density compared with untreated women would be expected to reduce the risk of bone fractures. Received: September 2000 / Accepted: December 2000     

The effect of intranasal salmon calcitonin on postmenopausal bone turnover as assessed by biochemical markers: Evidence of maximal effect after 8 weeks of continuous treatment

Although treatment with intranasal salmon calcitonin (sCT) has been shown to effectively inhibit postmenopausal bone loss, there is still controversy over both timing and the duration of its application. In an open prospective study, we therefore assessed the effect of short-term intranasal sCT on postmenopausal bone turnover, employing biochemical markers of bone metabolism. Ten early postmenopausal, previously untreated women (1–5 years after menopause) with biochemical evidence of increased bone resorption and a low bone mineral density at baseline were treated with intranasal sCT (100 IU B.I.D.) for a period of 3 months. Oral calcium (500 mg/day) was administered simultaneously, and during a further 3 month followup interval. Treatment with sCT resulted in a pronounced suppression of bone resorption markers with a maximum effect reached after 8 weeks of therapy: as compared to the respective baseline values, mean levels decreased by −26.2%±3.4% (P<0.001) for pyridinoline, −32.7%±3.5% (P<0.001) for deoxypyridinoline, −32.7%±3.3% (P<0.001) for hydroxyproline, and −24.1%±8.2% (P<0.001) for the amino-terminal telopeptide. In contrast, changes in bone formation markers of osteocalcin (−14.4%±4.8%,P<0.05) and C-terminal procollagen type I propeptide (−7.9%±3.9%, ns) were much less pronounced. Unexpectedly, after week 8 of the study all resorption markers showed a plateau and a trend to increase, although intranasal sCT was continued for a total of 12 weeks. This effect could not be attributed to the formation of anti-sCT antibodies. After cessation of treatment, both bone formation and resorption markers rapidly returned to baseline levels. Bone mineral density of both spine and hip showed no significant change during the observation period. Our results demonstrate that in postmenopausal women with a high bone turnover, intranasal treatment with 200 IU of sCT effectively reduces bone turnover and maintains bone mass, the maximum effect being reached after 8 weeks of treatment.     

Use of Phalangeal Bone Mineral Density and Multi-site Speed of Sound Conduction to Monitor Therapy with Alendronate in Postmenopausal Women

In women with postmenopausal osteoporosis (PMO), response to therapy with bisphosphonates is conventionally monitored using central-site (hip and spine) bone mineral density (BMD), but more convenient alternatives are desirable. During a randomized parallel-group study of the efficacy of once-weekly (80 mg vs 160 mg) oral alendronate in the treatment of PMO, 81 women (mean age 70.2 years ± 4.6 SD) had BMD measurements of total hip (TH) and lumbar spine (LS) (L1–L4, Hologic); and of the middle phalanx of the middle digit of the non-dominant hand (accuDXA) at baseline and after 6 and 12 months of therapy with alendronate. At the same timepoints, subjects also had measurements of speed of sound (SOS) through bone at four sites (distal 1/3 radius, proximal phalanx of the third finger, midshaft of the tibia and fifth metatarsal) using the Sunlight Omnisense Ultrasound Bone Sonometer. Data from both patient groups were pooled for this analysis. Mean TH BMD at baseline was 0.705 g/cm²± 0.093 (SD) and increased by 1.7%± 2.3% and 2.5%± 2.3% at 6 and 12 months respectively (p= 0.09 and p<0.0001). Mean LS BMD at baseline was 0.718 ± 0.076 g/cm² and increased by 3.9%± 3.6% and 6.1%± 3.5 % at 6 and 12 months respectively (both p<0.0001). There was no statistically significant change from baseline in mean BMD by accuDXA at either 6 or 12 months. The only statistically significant changes in SOS were at the radius (decrease in SOS at 12 months, p = 0.04) and tibia (increase at 6 months, p<0.01, but no change between baseline and 12 months). Baseline correlation coefficients between accuDXA and LS and TH DXA were 0.22 (p= 0.05) and 0.27 (p= 0.02) respectively. Correlation coefficients between SOS and LS DXA ranged from 0.05 to 0.22; and between SOS and TH DXA ranged from –0.08 to 0.10 (all p= NS). These data suggest that the response to alendronate therapy over this time period cannot be measured by accuDXA or Sunlight SOS at the sites studied. Received: 26 June 2001 / Accepted: 27 September 2001     

Comparison of renal responses to synthetic human PTH(1–34) administration in normal young and elderly male subjects

Summary A parathyroid hormone (PTH) loading test with synthetic human PTH(1–34) was performed in 7 young and 6 elderly normal males. The elderly subjects had significantly higher mean basal levels of serum PTH than the young subjects (0.262±0.035(SE) vs 0.097±0.012 ng Eq/ml,P<0.001). When human PTH(1–34) at a dose of 100 U was administered to these subjects, the mean increases in urinary excretions of adenosine cyclic 3′, 5′-monophosphate(cAMP) and inorganic phosphorus (Pi), expressed as increases in absolute amounts per unit time, were significantly lower in the elderly subjects. (3.65±1.02 vs 7.41±1.05 μmol/h,P<0.05 for cAMP and 14.7±6.3 vs 41.8±8.6 mg/2h,P<0.05 for Pi) and an inverse correlation was found between the serum PTH levels and the increases in urinary cAMP excretion (μmol/hr; r=−0.63,P<0.05). However, when corrected for the glomerular filtration rate (GFR) and the units of PTH administered per kg body weight, the increases were not significantly different in the two groups (elderly 52.1±7.5 vs young 60.0±19.2 nmol·kg/100 ml GFR·U·h for cAMP and 0.315±0.061 vs 0.186±0.044 mg·kg/100 ml GFR·U·2 h respectively for Pi). These results indicated that the decreased response of the kidney to PTH in elderly subjects can be explained mainly by the decreased functional mass of the kidney, possibly with some contribution of down-regulation of PTH receptors owing to increase in the blood level of endogenous PTH in elderly subjects. Further investigations are needed to ascertain why there was decreased response of the kidney to PTH in elderly people.     

Insulin resistance causes human gallbladder dysmotility

Obesity, diabetes, and hyperlipidemia are known risk factors for the development of gallstones. A growing body of animal and human data has correlated insulin resistance with organ dysfunction. The relationship among obesity, diabetes, hyperlipidemia, and abnormal gallbladder motility remains unclear. Therefore, we designed a study to investigate the association among obesity, insulin resistance, hyperlipidemia, and gallbladder dysmotility. One hundred ninety-two healthy adult nondiabetic volunteers were studied. Gallbladder ultrasounds were performed before and after a standardized fatty meal. A gallbladder ejection fraction (EF) was calculated, and an EF of <25% was considered abnormal. Serum was analyzed for cholesterol, triglycerides, cholecystokinin, leptin, glucose, and insulin. The homeostasis assessment model (HOMA) was used to determine insulin resistance. The volunteers had a mean age of 38 years (range, 18–77), and 55% were female. Thirty subjects (15%) had gallstones and were excluded from the study. Thirty subjects (19%) had abnormal gallbladder motility (EF <25%). In lean subjects (n=96) fasting glucose was significantly increased in the 16 subjects with gallbladder EF <25% versus the 80 subjects with gallbladder EF >25% (109±20 mg/dl versus 78±2 mg/dl, P<0.05). Similarly, the HOMA index was significantly greater in subjects with gallbladder EF <25% versus gallbladder EF >25% (3.3±1.2 versus 2.0±0.2, P<0.05). In obese subjects (n=66), fasting glucose, insulin, and insulin resistance were not associated with a gallbladder EF <25%. These data suggest that in lean, nondiabetic volunteers without gallstones, gallbladder dysmotility is associated with an elevated fasting glucose as well as a high index of insulin resistance. We conclude that insulin resistance alone may be responsible for gallbladder dysmotility that may result in acalculous cholecystitis or gallstone formation. Presented at The Society for Surgery of the Alimentary Tract, May 15–18, 2005, Chicago, Illinois (oral presentation). Supported by National Institutes of Health grants K23 DK62260 and R-01 DK44279.     

Continuous Loss of Bone During Chronic Immobilization: A Monozygotic Twin Study

Acute immobilization is associated with rapid loss of bone. Prevailing opinion, based on population cross-sectional data, assumes that bone mass stabilizes thereafter. In order to address whole-body and regional skeletal mass in long-term immobilization, monozygotic twins were studied, one of each twin pair having chronic spinal cord injury (SCI) of a duration ranging from 3 to 26 years. The research design consisted of the co-twin control method using 8 pairs of identical male twins (mean ± SD age, 40 ± 10 years; range 25–58 years), one of each set with SCI. The twins were compared by paired t-tests for total and regional bone mineral content (BMC) and bone mineral density (BMD) measured by dual-energy X-ray absorptiometry. Linear regression analyses were performed to determine the associations of age or duration of injury with the differences between twin pairs for total and regional skeletal bone values. In the SCI twins, total-body BMC was significantly reduced (22%± 9%, p<0.001), with the predominant sites of reduction for BMC and BMD being the legs (42%± 14% 35%± 10%, p<0.0001), and pelvis (50%± 10% and 29%± 9%, p<0.0001). Duration of SCI, not age, was found to be linearly related to the degree of leg bone loss in SCI twins (BMC: r ²= 0.60, p<0.05; BMD: r ²= 0.70, p<0.01). Our findings suggest that pelvic and leg bone mass continues to decline throughout the chronic phase of immobilization in the individual with SCI, and this bone loss appears to be independent of age. Received: 28 September 1998 / Accepted: 28 December 1998     

The effect of two different doses comprising the simultaneous administration of intravenous B-complex vitamins and oral folic acid on serum homocysteine levels in hemodialysis patients

Background: Several regimens using different doses of folic acid (FA) alone or supplemented with B-complex vitamins (BCVs) have been tested for their ability to reduce total homocysteine (tHcy) serum levels in hemodialysis (HD) patients. In the present study, we assessed the effect of two different doses comprising the simultaneous administration of intravenous (IV) BCVs and an oral FA supplementation on serum tHCy levels in HD patients. Patients–methods: In a cohort of 49 patients (31 male, 18 female) undergoing chronic HD treatment for a mean of 40.0±40.7 months, serum concentrations of tHcy, folate and vitamin-B12 (vB12) were determined at the end of three sequential periods as follows: 20 weeks without any BCV and/or FA supplementation (period A), 20 weeks with a dose comprising the simultaneous administration of IV BCVs and an oral supplementation of 5 mg of FA once a week (period B), and 20 weeks with a dose comprising the simultaneous administration of IV BCVs and an oral supplementation of 5 mg of FA thrice a week (period C). An IV dose of BCVs consisting of a 5 mL solution containing vitamin B₁ (250 mg), vitamin B₆ (250 mg) and vitamin B₁₂ (1.5 mg) was administered at the end of hemodialysis. Results: Mean serum tHcy levels were significantly higher at the end of period A relative to levels at the end of periods B and C (35.8±23 μmol/L vs. 22.0±17.6 and 15.0±4.5 μmol/L, respectively; p < 0.000001). Mean serum folate levels and mean serum vB12 levels were significantly lower at the end of period A relative to levels at the end of periods B and C (p < 0.000001). Mean serum tHcy levels were lowest at the end of period C (p < 0.000001 in comparison to periods A and B), and 26 of the 49 HD patients (67.3%) possessed tHcy levels below 16 μmol/L. Conclusions: In HD patients, high doses consisting of the simultaneous administration of IV BCVs and an oral FA supplementation resulted in the efficient reduction of serum tHcy levels.     

Effects of endogenous acetaldehyde production by disulfiram and ethanol feeding on rat pancreas

Exogenous acetaldehyde infusion can induce pancreatitis-like injury of the pancreas in some isolated pancreas models, whereas in vivo such treatment has failed to induce pancreatitis. In vivo exogenous acetaldehyde may not be effective because it is rapidly metabolized. The aim of this study was to investigate whether endogenous acetaldehyde accumulates in the pancreas after ethanol feeding when acetaldehyde metabolism is blocked by disulfiram, and whether this treatment can induce pancreatitis-like injury in the rat. The liver was studied for comparison. In part I of the experiment, adult male Wistar rats were given water (n = 24), ethanol (n = 24), disulfiram (n = 24), and ethanol plus disulfiram for 1 week (n = 24) or 3 weeks (n = 24) and for 3 weeks with (n = 6) and without (n = 6) hypovolemia. In part II of the experiment, rats were given water (n = 6), ethanol (n = 6), and high-dose disulfiram (n = 6) and ethanol plus high-dose disulfiram (n = 6). Ethanol and acetaldehyde concentrations in blood, liver, and pancreas were measured. Animal behavior was monitored, and weight changes, plasma amylase activity, water content, and histomorphology of the pancreas and liver were studied without knowing the group. No increases in plasma amylase activity and no histomorphologic changes in the pancreas were observed under light or electron microscopy in part I of the experiment. In part II, treatment with ethanol induced acetaldehyde accumulation in the liver (33.6 ±2.6 (μmol/L), but to a lesser degree in the blood (9.6 ±1.6 μmol/L) and pancreas (5.0 ±1.2 μ,mol/L). Ethanol plus disulfiram induced marked accumulation of acetaldehyde in the liver (83.2 ±15.9 μmol/L), blood (280.0 ±47.4 μnol/L), and pancreas (43.6 ±4.7 μ,mol/L). When tissue acetaldehyde levels reached 30 to 40 μ,mol/L, we found a decrease in zymogen granules along with formation of small intracytoplasmic vacuolizations in the acinar cells and accumulation of lipid droplets in the hepatocytes, whereas physiologic signs of pancreatitis (hyperatnylasemia, edema) or increases in liver enzymes did not develop. High levels of acetaldehyde accumulate in the liver and pancreas w ith the treatment described. Although this was accompanied by lipid degeneration of the hepatocytes and some subcellular changes in the acinar cells, physiologic signs of pancreatitis did not develop. Thus acetaldehyde accumulation alone, or in combination with hypovolemia, is not responsible for the induction of acute pancreatitis. Supported by grants from the Paulo Foundation and the Medical Research Fund of Tampere University Hospital.     

Surgical treatment of Roux stasis syndrome

We wondered whether the slow gastric emptying of the Roux stasis syndrome could be improved by performing a corrective ‘uncut’ Roux operation. Five dogs had a standard Roux gastrectomy and placement of serosal electrodes on the proximal jejunum and Roux limb. After recovery, baseline myoelectrical and gastric emptying data were collected. The animals then underwent a second operation: take down of the Roux limb, restoration of jejunal continuity, and construction of an ‘uncut’ Roux limb. After the animals recovered, the tests were repeated. The slow frequency of pacesetter potentials (PPs) in the standard Roux limb (mean ± standard error of the mean 14 ± 0.4 cpm) was unchanged after the uncut Roux operation (14 ± 0.5 cpm, P>0.05). However, a greater percentage of PPs propagated aborally in the uncut Roux limb (81% ±4%) than in the standard Roux limb (53% ±7%, P <0.05). Nonetheless, gastric emptying of a 250 ml 10% dextrose liquid meal was not speeded by the uncut Roux operation (uncut Roux = 36% ±5% emptied by 20 minutes vs. standard Roux = 35% ±7%; P >0.05). Bile acid concentrations in gastric aspirates were minimal after both operations (0.7 ± 0.2 μmol/L vs. 0.6 ±0.1 (μmol/L; P >0.05). The conclusion was that more PPs propagated in the aborad direction in the uncut Roux limb than in the standard Roux limb, but gastric emptying was not speeded by the uncut Roux operation. Both operations were equally effective in preventing bile reflux into the gastric remnant. Supported by National Institutes of Health grant DK18278 and the Mayo Foundation. An abstract of this work was presented at the Annual Meeting of the American Gastroenterological Association, San Diego, Calif., May 17, 1995, and published in Gastroenterology 108:A101, 1995.     

Contractile response of different segments of the latissimus dorsi muscle to chronic stimulation

Objective: This study was planned to investigate if there is any difference in terms of the muscle force between the distal and proximal segments of the latissimus dorsi muscle.Subjects and Methods: An implantable mock circulation system was placed around the latissimus dorsi muscle. The wrapping procedure around the implantable mock circulation was performed by using two different latissimus dorsi muscle segments. In group 1, the very proximal and in group 2, very distal part of the latissimus dorsi were wrapped. The main differences is the blood supply to the distal part of the latissimus dorsi that was interrupted during dissection. During the stimulation period which lasted 120 minutes, the pressure developed in this system and adenosine triphosphate (ATP) levels were measured.Results: The stimulation at 20 Hz did not result in any change in pressure and metabolic data. When it was switched to 43 and 85 Hz, ATP levels decreased with a resultant drop in pressure in group 2. However ATP levels were 15.9±2.2 μmol/gr and 14.8±2.5 μmol/gr in group 1, 12.0±1.4 μmol/gr and 6.1±1.2 μmol/gr in group 2 at 43 and 85 Hz respectively (p<0.05) at the end of the 90 minutes. The pressures at the same time interval were 89±11 and 102±7 mmHg in group 1, 61±7 and 65±8 mmHg in group 2 (p<0.05).Conclusion: In this study, we demonstrated that changes in the distal segment of the latissimus dorsi muscle affects its performance in terms of metabolic and pressure changes during high frequency electrical stimulation at 43 and 85 Hz.     

Phenotypic Characteristics of Bone in Carbonic Anhydrase II-Deficient Mice

Carbonic anhydrase II (CAII)-deficient mice were created to study the syndrome of CAII deficiency in humans including osteopetrosis, renal tubular acidosis, and cerebral calcification. Although CAII mice have renal tubular acidosis, studies that analyzed only cortical bones found no changes characteristic of osteopetrosis. Consistent with previous studies, the tibiae of CAII-deficient mice were significantly smaller than those of wild-type (WT) mice (28.7 ± 0.9 vs. 43.6 ± 3.7 mg; p < 0.005), and the normalized cortical bone volume of CAII-deficient mice (79.3 ± 2.2%) was within 5% of that of WT mice (82.7 ± 2.3%; p < 0.05), however, metaphyseal widening of the tibial plateau was noted in CAII-deficient mice, consistent with osteopetrosis. In contrast to cortical bone, trabecular bone volume demonstrated a nearly 50% increase in CAII-deficient mice (22.9 ± 3.5% in CAII, compared to 15.3 ± 1.6% in WT; p < 0.001). In addition, histomorphometry demonstrated that bone formation rate was decreased by 68% in cortical bone (4.77 ± 1.65 μm³/μm²/day in WT vs. 2.07 ± 1.71 μm³/μm²/day in CAII mice; p < 0.05) and 55% in trabecular bone (0.617 ± 0.230 μm³/μm²/day in WT vs. 0.272 ± 0.114 μm³/μm²/day in CAII mice; p < 0.05) in CAII-deficient mice. The number of osteoclasts was significantly increased (67%) in CAII-deficient mice, while osteoblast number was not different from that in WT mice. The metaphyseal widening and changes in the trabecular bone are consistent with osteopetrosis, making the CAII-deficient mouse a valuable model of human disease.     

Effect of carnitine supplementation on lipid profile and anemia in children on chronic dialysis

We prospectively evaluated the effects of L-carnitine supplementation on plasma free carnitine (FC) levels, serum lipid profile, and erythropoietin (rhEPO) requirement in 24 children treated with peritoneal dialysis (PD; n = 16) or hemodialysis (HD; n = 8). The study was divided into a 3-month observation period, and a 3-month treatment period during which patients received 20 mg/kg per day of L-carnitine given orally. Clinical, biochemical, and hematological data were collected every 3 months. FC levels were measured in plasma and peritoneal dialysate by tandem mass spectrometry. There were no statistically significant changes in lipid levels, hemoglobin, or rhEPO requirements during the course of the study. Fifteen patients (13 PD, 2 HD) had plasma FC levels measured before and after treatment; FC levels increased from 32.1 ± 14.1 μmol/l to 80.9 ± 38.7 μmol/l (P < 0.001). In PD patients, dialysate FC losses increased from 106 ± 78 μmol/day at baseline to 178 ± 119 μmol/day after supplementation. Positive correlations between FC plasma levels and dialysate levels (R = 0.507) or daily excretion (R = 0.603) were found after treatment. In our case series, an oral dose of 20 mg/kg per day of L-carnitine restored FC levels and produced a positive carnitine balance with no significant effects on hematological parameters or lipid profile over a 3-month period. Prolonged treatment duration may be required to obtain significant results.