Modulators of growth in primary culture of rat proximal tubular cells

Summary: The effects of known growth factors and circulating serum factors in animals following unilateral nephrectomy on cellular hypertrophy and hyperplasia were studied in primary culture of rat proximal tubular cells. the cultured cells were derived from normal rat kidney, as well as from rat kidneys which had undergone compensatory renal hypertrophy. Cellular thymidine incorporation was stimulated with insulin-like growth factor 1 (IGF-1; P <0.001), epidermal growth factor (EGF; P <0.01) and additively by the combination of IGF-1+EGF ( P <0.0001). Transforming growth factor β₁ (TGF β₁) potently inhibited thymidine incorporation in the presence or absence of these growth factors. Cellular protein content was increased in the presence of IGF-1 ( P <0.01). the addition of 10% serum harvested from sham operated (Sx) animals to cell cultures derived from Sx animals significantly increased cell protein content ( P <0.02), and stimulated cellular thymidine incorporation ( P <0.005). the addition of 10% serum harvested from unilaterally nephrectomized (Nx) animals further enhanced the growth response. In cell cultures derived from Nx rats, a further marked stimulation of thymidine incorporation and cellular protein was observed in the presence of both Sx and Nx serum, indicating an increased sensitivity of these cells to serum-derived factors. In summary, the growth factors tested have direct effects in regulating rat renal tubular cell growth. Circulating factors stimulating proximal tubular cell growth are present in animals which have undergone nephrectomy. Renal tubular cells derived from animals with compensatory renal hypertrophy are sensitized to the effects of the manipulations which enhance proximal tubular cell growth.     

Vitamin D deficiency, CD4+CD28null cells and accelerated atherosclerosis in chronic kidney disease

Aim: Cardiovascular disease (CVD) is the leading cause of death among chronic kidney disease (CKD) patients. The role of vitamin D remains controversial in this process. We evaluated the relationship between 25‐hydroxyvitamin D, abnormal T helper cells (CD4+CD28null cells), systemic inflammation and atherosclerosis in CKD patients. Methods: A total of 101 stage 4–5 non‐dialysis CKD patients and 40 healthy controls were studied. Common carotid artery intima media thickness (CCA‐IMT) was measured with an ultrasound system. 25(OH) vitamin D and highly sensitive C‐reactive protein (hsCRP) were measured in serum by enzyme linked immunosorbent assay. The frequency of circulating CD4+CD28null cells was evaluated by flowcytometry. Results: CKD subjects exhibited higher CCA‐IMT (0.71 ± 0.01 vs 0.56 ± 0.01 mm, P < 0.0001), hsCRP (90.7 ± 5.8 vs 50.1 ± 8.6 µg/mL, P < 0.0001), CD4+CD28null cell frequency (9.1 ± 0.9 vs 3.6 ± 0.5%, P < 0.0001) and lower 25(OH) vitamin D levels (17.9 ± 1.9 vs 26.9 ± 3.5 ng/mL, P < 0.0001). In CKD subjects, serum 25 (OH) vitamin D level showed a strong inverse correlation with CCA‐IMT (r = ?0.729, P < 0.0001) and correlated with CD4+CD28null cell frequency (r = ?0.249, P = 0.01) and hsCRP (r = ?0.2, P = 0.047). We also noted correlation of IMT with patient age (r = 0.291, P = 0.004) and CD4+CD28null cells (r = 0.34, P = 0.001). On multiple regression analysis, 25(OH) vitamin D level, diabetic status and CD4+CD28null cell frequency exhibited independent association with IMT in CKD subjects. Conclusions: Vitamin D deficiency, inflammatory activation and higher frequency of CD4+CD28null T lymphocyte population correlate with preclinical atherosclerotic changes in CKD population. These findings suggest possible linkage between vitamin D metabolism and T cell modulation – abnormalities that may contribute to development of atherosclerosis in CKD.     

Normothermic cardiopulmonary bypass and cardioplegia reduce inotropic requirements and creatine kinase-MB after coronary artery bypass graft surgery

Purpose To determine whether normothermic cardiopulmonary bypass (CPB) and cardioplegia preserve myocardial function, reduce inotropic requirements, and reduce markers of myocardial ischemia following coronary artery bypass graft surgery (CABG). Methods We retrospectively reviewed the charts of 171 consecutive patients undergoing elective CABG by a single surgeon from April 1994 to December 1995. Hypothermic CPB with intermittent cold cardioplegia was used in 83 patients and normothermic CPB with intermittent warm cardioplegia in 88 patients. Demographic, surgical, hemodynamic, and inotropic requirements and laboratory data were reviewed. Results The duration of CPB was significantly shorter in the normothermic group (113±27vs 90±21 min;P<0.0001). After CPB the cardiac index was similar between groups, but significantly larger doses of both dopamine and dobutamine were required (8vs 5μg·kg⁻¹·min⁻¹,P<0.0001), and significantly more patients required norepinephrine administration in the hypothermic group (18%vs 6%;P=0.01). Postoperative peak values of creatine kinase MB fraction (CK-MB) were significantly lower in the normothermic group (80±60vs 55±54 IU·I⁻¹;P<0.0001). Conclusion Normothermic CPB and cardioplegia reduce inotropic requirements and CK-MB following CABG.     

Bone marrow stem cells-derived microvesicles protect against renal injury in the mouse remnant kidney model

Aims: Several studies have demonstrated administration of mesenchymal stem cells (MSC) could reverse kidney injury by paracrine mechanisms rather than by MSC transdifferentiation. Recently, a few researchers found microvesicles (MV) derived from MSC might be a paracrine mechanism for cell‐to‐cell communication. The aim of this study was to investigate the repair effects of MV in a 5/6 subtotal nephrectomy (Nx) mice model. Methods: The animals were randomly divided into four groups: Control, Nx, Nx + MSC and Nx + MV group. MSC were injected (1 × 10⁶/mouse) through caudal vein in Nx + MSC group at the second day after the surgery and MV were injected (30 µg/mouse) through caudal vein in Nx + MV group on alternate days. Mice were killed on day 7 after the first time of administration. Blood urea nitrogen (BUN), serum creatinine (Scr), uric acid (UA) and proteinuria were evaluated. Histopathology of kidney was analysed. Results: In Nx mice, the levels of Scr, UA and proteinuria were significantly decreased with administration of MV and MSC (P < 0.05). The remnant kidneys of MV and MSC‐treated Nx mice showed less fibrosis, interstitial lymphocyte infiltrates and less or absent tubular atrophy compared with the untreated Nx group. The Histological Score of Kidney in untreated mice was 3.13 ± 0.74, while in the MSC‐treated group it was 1.67 ± 0.47 and in the MV‐treated group it was 1.80 ± 0.44, nearly preserving normal morphology of the kidney (P < 0.01). Conclusion: This study showed MV protects against renal injury induced by 5/6 Nx, which could mimic the role of MSC in kidney repair. The research showed a newly potential therapeutic approach to kidney diseases.     

Verapamil prevents the apoptotic and hemodynamic changes in response to unilateral ureteral obstruction

Introduction: Obstruction of the urinary tract has marked effects on renal blood flow, glomerular filtration rate (GFR), and tubular function. Moreover, ureteral obstruction results in an injury response that can progress to irreversible renal fibrosis and tubular atrophy by apoptosis. Methods: We examined the effect of a calcium channel blocker (verapamil) on renal functions and the abundance of apoptotic (p53, Fas, proliferating cell nuclear antigen [PCNA]) markers 1 week after Unilateral Ureteral Obstruction (UUO). Results: Immunohistochemistry studies revealed that UUO was markedly associated with up-regulation in the expression of p53 (1550 ± 82 vs 100 ± 23%), Fas (657 ± 48 vs 100 ± 31%), and proliferating cell nuclear antigen (945 ± 70 vs 100 ± 17% of sham levels). Administration of verapamil normalized the up-regulation of apoptotic markers p53 (724 ± 116 vs 1550 ± 82%); Fas (162 ± 38 vs 657 ± 48%) and PCNA (353 ± 54 vs 945 ± 70%). Furthermore, tubular diameter, as an important marker for detecting tubular atrophy was significantly decreased compared to those in UUO rabbits. The percent area of interstitial fibrosis in UUO kidneys was significantly greater than that in Verapamil-treated kidneys. Importantly, Verapamil reduced the development of interstitial fibrosis in UUO rabbits. We measured the GFR and renal blood flow in UUO. Short-term Verapamil challenge partially prevented the decrease in GFR (non-treated UUO: 62 ± 14; Verapamil + UUO: 119 ± 7; Sham: 127 ± 23 μL·min⁻¹·kg body wt⁻¹, P < 0.05) and renal blood flow (non-treated UUO: 1.1 ± 0.4; Verapamil + UUO: 5.0 ± 0.2; sham: 6.3 ± 0.2 mL·min⁻¹·kg body wt⁻¹, P < 0.05). Conclusion: Verapamil significantly prevents impairment in renal function and also prevents the up-regulation of p53, Fas, and PCNA during UUO, demonstrating a marked renoprotective effect of Verapamil treatment in conditions with urinary tract obstruction.     

Induction of Functional Differentiation and Growth Inhibition In Vitro of Canine Osteosarcoma by 22-Oxacalcitriol,Calcitriol and All-trans Retinoic Acid

The effects of 22-oxacalcitriol (OCT), calcitriol and all-trans retinoic acid (ATRA) on the induction of functional differentiation and growth inhibition of the canine osteosarcoma cell line POS were investigated in vitro via bone differentiation markers and proliferation assays, respectively. The intracellular alkaline phosphatase (ALP) activity and the gamma-carboxyglutamic acid osteocalcin (GLA-OC) and procollagen type I C peptide (PIP) production were used as markers of differentiation. Treatment with 10⁻⁸ m concentrations of all drugs for 72 h significantly inhibited growth (P < 0.0001) and increased ALP activity and GLA-OC and PIP production in POS. OCT, calcitriol and ATRA significantly increased the: ALP activity from 1.58 ± 0.14 μmol/min/mg protein (mean ± SD; control) to 2.50 ± 0.09 (P < 0.0001), 2.30 ± 0.14 (P < 0.0001) and 2.00 ± 0.14 (P = 0.0008), respectively; GLA-OC production from 0.71 ± 0.01 ng/ml (control) to 2.87 ± 0.01 (P < 0.0001), 2.87 ± 0.11 (P < 0.0001) and 1.36 ± 0.06 (P < 0.0001), respectively; and PIP production from 433.91 ± 23.29 ng/ml (control) to 536.54 ± 15.46 (P = 0.0002), 497.06 ± 1.99 (P = 0.0028) and 481.66 ± 0.01 (P = 0.0104), respectively. This study demonstrated that treatment with these drugs induced a phenotypic maturation of POS cells into cells that exhibit the properties of functionally mature bone cells with parallel growth inhibition. The effects of these drugs on functional differentiation may be useful to complement the progression of a normal osteogenic differentiation process in the sarcoma.     

IGF-1 as an early marker for low bone mass or osteoporosis in premenopausal and postmenopausal women

To find out which of the following parameters—serum levels of insulin-like growth factor 1 (IGF-1), osteoprotegerin (OPG), leptin, osteocalcin (OC), and urinary excretion of N-terminal telopeptide of type I collagen (NTx), can be used as an early marker for osteopenia/osteoporosis in women diagnosed by dual-energy X-ray absorptiometry (DXA), 282 premenopausal and 222 postmenopausal women aged 20–75 years were investigated by the measurement of bone mineral densities (BMDs) at lumbar spine (LS) and femoral neck (FN) by DXA, together with serum concentrations of IGF-1, OPG, leptin, OC, and urinary NTx. The characteristics of the earliest marker(s) were tested with the receiver operating characteristic (ROC) analysis. The area under the curve (AUC), sensitivity, and specificity parameters were determined. It was revealed that serum levels of IGF-1 and leptin changed the earliest, with both markers significantly decreasing (P < 0.0001) or increasing (P = 0.020), respectively, at age 30. However, in ROC analysis, IGF-1 was the only early parameter that had the capacity to differentiate the low bone mass/osteoporosis women from the normal ones (P < 0.0001). If the serum level of IGF-1 at 1.5 SD below its peak was adopted as a cutoff point, it could identify women with low bone mass/osteoporosis with a sensitivity of 73% and specificity of 67%. In the premenopausal women subgroup analysis, the low bone mass women (30/282, 10.6%) were older (38.2 ± 1.7 vs. 34.5 ± 0.5 years; P = 0.026), with lower serum levels of IGF-1 (215.1 ± 22.4 vs. 278.8 ± 9.4 ng/ml; P = 0.02) and less lean mass (33.1 ± 0.6 vs. 34.8 ± 0.2 kg; P = 0.010) than the normal ones. After controlling for age, the serum level of IGF-1 had a weak, but still significant, positive correlation with lean mass (r = 0.17, P < 0.001). In conclusion, measurement of serum IGF-1 in young women may help in the early identification of those at risk for developing low bone mass and osteoporosis.     

Conventional nutritional counselling maintains nutritional status of patients on continuous ambulatory peritoneal dialysis in spite of systemic inflammation and decrease of residual renal function

Aim: To evaluate the effect of nutritional counselling on nutritional status in peritoneal dialysis patients. Methods: Twenty‐nine peritoneal dialysis patients were randomly selected to receive conventional nutritional counselling during 6 months of follow up. All patients had monthly clinical and biochemical evaluations, and assessments of dialysis adequacy, inflammation and nutritional status at 0, 3 and 6 months. Results: Moderate‐severe malnutrition decreased 28% whereas normal nutrition increased 23% at final evaluation (non‐significant). Calorie and protein intake remained stable throughout the study (baseline vs final, calorie: 24 ± 8 vs 23 ± 5 Kcal/kg; protein: 1.1 ± 0.5 vs 1.0 ± 0.3 g/Kg, respectively). On the other hand, triceps (16 ± 6 vs 18 ± 8 mm) and subscapular (17 ± 8 vs 20 ± 5 mm) skinfold thicknesses, and mid‐arm circumference (27 ± 3 vs 28 ± 3 mm) significantly increased; mid‐arm muscle area displayed a non‐significant trend to increase (30 ± 9 vs 31 ± 9 cm²) whereas serum albumin significantly increased at the end of study (2.67 ± 0.46 vs 2.94 ± 0.48 g/dL). At final evaluation, median renal creatinine clearance decreased (6.3 (0.8–15.3) vs 2.0 (0.1–6.3) L/week per 1.73 m²) whereas interleukin‐6 increased (2.33 (1.9–7.0) vs 4.02 (2.1–8.4) pg/mL). Conclusion: Even though conventional nutritional counselling, as an isolated measure, did not significantly improve all nutritional parameters, it prevented a greater deterioration during 6 months. Nutritional counselling maintained the nutritional status in spite of a decrease in residual renal function and higher systemic inflammation.     

A comparison of propofol and chloral hydrate for sedation of young children during magnetic resonance imaging scans*

The purpose of this study was to compare the effects of two methods of providing sedation for young children undergoing magnetic resonance imaging (MRI) studies on efficiency of scanner utilization. Thirty-nine patients were randomized to receive either propofol or chloral hydrate. Age and gender distributions were not significantly different between the groups. Induction time was significantly less for propofol than for chloral hydrate (6 ± 3 min vs 41 ± 9 min; P < 0.0001); and recovery time for propofol was significantly shorter than for chloral hydrate (18 ± 7 min vs 47 ± 28 min; P < 0.0001). Procedure times were not significantly different. Three of 19 patients who received chloral hydrate moved and their scans were interrupted; two of these received propofol. None of the patients in the propofol group moved. Utilization efficiency of the MRI scanner, defined as 100 ± (Procedure Time)/(Induction Time + Procedure Time), was 87 ± 6% for propofol and 45 ± 13% for chloral hydrate. These data demonstrate that propofol sedation allows the MRI scanner to be utilized more efficiently than chloral hydrate sedation.     

Low intensity laser irradiation inhibits tritiated thymidine incorporation in the hemopoietic cell lines HL-60 and U937

The purpose of this study was to determine the effect of low intensity laser irradiation (660 nm, 12 mW, 5 kHz) on tritiated thymidine incorporation in two hemopoietic cell lines, HL-60 and U937. Cells were suspended at a concentration of 1 × 10⁶/ml in their respective serum-free media and irradiated at energy densities from 1.0 to 11.5 J/cm². Twenty-four hours after irradiation the cells were assayed for their ability to incorporate tritiated thymidine (³H-TdR) in comparison with nonirradiated cells. Analysis by two-way analysis of variance (ANOVA) for unrelated groups showed that laser irradiation at all energy densities ? 5.8 J/cm produced a significant decrease in ³H-TdR incorporation (P < 0.05) into HL-60 cells. In U937 cells, irradiation at energy densities of 5.8, 7.2, and 11.5 J/cm² caused a similar reduction in ³H-TdR incorporation (P < 0.01), although not at 8.6 and 9.6 J/cm². The temperature of each cell suspension was recorded both during and immediately postirradiation, and no significant thermal changes were observed. These findings demonstrate a direct photobiological effect of laser irradiation on these two cell lines. The precise mechanism for this effect is unknown but may have significance in understanding the biological action of laser's known therapeutic effectiveness in promoting wound repair. © 1994 Wiley-Liss, Inc.     

Up-regulation of ICAM-1 and VCAM-1 expression during macrophage recruitment in lipid induced glomerular injury in ExHC rats

Summary: A number of studies have demonstrated an important role for macrophages (Mo) in lipid induced glomerular injury; however, little is known of the mechanisms which facilitate Mo infiltration in this disease. the present study examined the expression of adhesion molecules, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) during the development of glomerular Mo infiltration in ExHC rats; a strain which is susceptible to lipid induced glomerular injury. Twenty-five male 6 week old ExHC rats were placed on a normal diet supplemented with 3% cholesterol, 0.6% sodium cholate and 15% olive oil (high-cholesterol diet, HCD). Groups of five rats were killed prior to the beginning of the HCD or after 3 days, 1, 2 and 6 weeks on a HCD. A group of five matched ExHC rats on a normal diet served as a control. ExHC rats fed a HCD showed marked hypercholesterolaemia in the absence of any increase in plasma triglyceride levels from day 3 (190 ± 14 vs 42 ± 2 mg/dL in control; mean ± s.e.m., P<0.01), and developed mild proteinuria (21.9 ± 2.7 vs 5.2 ± 0.5 mg/24 h in control; P<0.01) and segmental glomerular lesions at week 6. Immunoperoxidase staining identified a significant increase in glomerular ED1⁺Mo at week 1 (2.0 ± 0.2 vs 1.0 ± 0.1 ED1⁺Mo/glomerular cross-section in control, P<0.01) which was further increased at week 6 (6.9 ± 0.4 ED1⁺Mo/gcs). There was also a significant increase in glomerular cells expressing the adhesion molecule ligands lymphocyte function-associated antigen-1 (LFA-1) and very late antigen-4 (VLA-4). Coincident with Mo infiltration, there was an increase in the intensity of glomerular ICAM-1 protein expression as shown by antibody staining. In addition, northern blot analysis of cortical RNA and in situ hybridization demonstrated an increase in glomerular ICAM-1 and VCAM-1 mRNA expression from day 3 onwards. In conclusion, these results suggest that both ICAM-1/LFA-1 and VCAM-1/VLA-4 interactions play an important role in Mo recruitment and accumulation during the development of lipid induced glomerular injury.     

Effects of growth hormone on growth factors after renal transplantation

Growth retardation occurs frequently in renal transplanted children (RTx) and can be improved by growth hormone (GH) treatment. This study retrospectively examines the insulin-like growth factor-1 (IGF-1) and IGF binding protein (IGFBP) profile of ten growth-retarded children previously given renal allografts, after 1 year of GH treatment period. Ten prepubertal patients (nine boys and one girl) were investigated. They had a mean chronological age (CA) of 11.4±1.1 years and a mean bone age (BA) of 7.3±0.9 years. Mean height was –3.9±0.4 SD units below the mean for CA. The mean body mass index (BMI) was 16.9±0.6 and the mean inulin clearance was 36.5±4.9 ml/min/1.73 m². Recombinant hGH was given at 4 IU/m²/day. Plasma GH, total and free IGF-1, IGFBP-2 and -3 were measured by specific radioimmunoassay (RIA). IGFBPs were characterized by SDS PAGE techniques and ligand and immunoblot analyses. Mean velocity was markedly increased (P<0.01) after 1 year of GH therapy, expressed as SD score for BA. The range of growth response was wide. The total and free plasma IGF-1 increased (P<0.01) by about 100% (mean values after GH therapy: 95.9± 2.1 nM and 165±29 pM, respectively). Plasma IGFBP-3 concentrations increased by about 40% (mean value: 148±18 pM, P<0.01), with a concomitant increase in both intact IGFBP-3 and its 30-kDa proteolytic fragment. There was no change in plasma IGFBP-2 concentration. Both mean values of inulin clearance and BMI were unchanged during the treatment. In view of the IGF-1/IGFBP concentration changes, there should have been an even better growth response to GH therapy in these patients. This strongly suggests IGF-1 insensitivity, probably as a result of corticosteroid therapy. Received: 12 April 2000 / Revised: 31 July 2000 / Accepted: 1 August 2000     

Increased coated-platelet levels in chronic haemodialysis patients

Aim: To determine if levels of coated‐platelets, which are potentially pro‐thrombotic, are increased in end‐stage renal disease patients on haemodialysis, a condition associated with high cardiovascular disease risk. Methods: In a cross‐sectional observational study, coated‐platelet levels were measured by flow cytometry in 25 end‐stage renal failure haemodialysis patients and 25 controls without renal disease. Associations between coated‐platelet levels and clinical and biochemical factors relevant to renal and cardiovascular disease were evaluated. Results: Mean ± SD coated‐platelet levels were higher in the dialysis group than in the control group (39.3 ± 14.3% vs 30.9 ± 10.3%, P = 0.02). The number of subjects with high coated‐platelet levels (>40%) was larger in the dialysis than in the control group (13/25 vs 4/25, χ² test, P = 0.007). On univariate analysis, coated‐platelet levels correlated with serum C‐reactive protein levels in renal failure (r = 0.47, P = 0.02) and inversely with white cell count in the control group (r = ?0.60, P = 0.001). Coated‐platelet levels were higher in dialysis patients reporting alcohol abstinence than among those reporting ‘social’ drinking (44.3 ± 12.6 vs 28.8 ± 13.5%, P = 0.01). Age, gender, body weight, smoking, diabetes, lipid levels and lipid‐lowering drugs were not associated with coated‐platelet levels (all P > 0.05). Conclusion: Coated‐platelet levels are increased in haemodialysis patients relative to subjects with normal renal function, and are related to inflammation and alcohol abstinence. Other vascular risk factors, such as smoking, lipids and diabetes, were not related to coated‐platelet levels. Coated‐platelets may be implicated in the increased thrombosis and vascular risk in end‐stage renal disease.     

Treatment with a cyclin-dependent kinase inhibitor, seliciclib, is effective in reducing glomerular macrophage numbers and the severity of established experimental glomerulonephritis

Aim: The cyclin‐dependent kinase inhibitor, seliciclib (R‐roscovitine, CYC202), has anti‐proliferative activity through its inhibition of cyclin‐dependent kinase 2. We hypothesized that treatment with seliciclib would reduce glomerular macrophage numbers and glomerular crescent formation in experimental crescentic glomerulonephritis even when treatment is started after onset of disease. Method: Nephrotoxic nephritis (NTN) was induced in Wistar Kyoto rats. In experiment 1, seliciclib (150 mg/kg per day) was given by oral gavage from 1 h before induction of NTN and continued to day 14. In experiment 2, treatment was started on day 4 of NTN and continued to day 14 in order to examine the effect of seliciclib in established glomerulonephritis. Results: In experiment 1, seliciclib reduced proteinuria (119.5 ± 13.9 vs 191.4 ± 18.8 mg/day, P < 0.01), serum creatinine (54.0 ± 3.0 vs 81.0 ± 2.5 µmol/L, P < 0.005) and glomerular crescent score (23.9 ± 2.1 vs 44.6 ± 2.2, P < 0.005) in comparison with controls. In experiment 2, seliciclib ameliorated established glomerulonephritis, with reduction in proteinuria (58 ± 16 vs 165 ± 13 mg/day, P < 0.005), serum creatinine (39 ± 3 vs 62 ± 5 µmol/L, P < 0.05), glomerular macrophage numbers (6.8 ± 2.5 vs 18.5 ± 1.2 ED1+ cells per glomerular cross section, P < 0.05), glomerular cell proliferation (1.2 ± 0.37 vs 4.2 ± 0.80 bromodeoxyuridine (BrdU)+ cells per glomerular section, P < 0.05) and crescent score (10.8 ± 1.6 vs 43.9 ± 1.4, P < 0.05), in comparison with the controls. Conclusion: Seliciclib is effective in both prevention and treatment of established crescentic glomerulonephritis in Wistar Kyoto rats, in association with a reduction in the number of glomerular macrophages. We suggest that seliciclib, or other cyclin‐dependent kinase inhibitors, may represent a novel therapeutic approach for patients with proliferative glomerulonephritis.     

Comparison between in vivo and in vitro pharmacokinetics of succinylcholine in humans

Purpose. To compare the in vivo and in vitro pharma-cokinetics of succinylcholine (SCh) in humans. Methods. A bolus of SCh 1 mg·kg⁻¹ (n = 7) or 2 mg·kg⁻¹ (n = 11) was given to 18 patients anesthetized with thiopental. Arterial blood samples for determination of in vivo SCh concentrations were collected every 30 s for 5 min. Another 20-ml blood sample was obtained before induction of anes-thesia for determination of in vitro SCh. Concentrations of SCh were measured by high-performance liquid chromato-graphy. In vivo and in vitro concentrations of SCh vs time data were analyzed by the one-compartment model. Results. The respective in vivo and in vitro pharmacokinetic parameters (SCh 1 mg·kg⁻¹ vs SCh 2 mg·kg⁻¹) were as follows: Plasma clearance was 4.17 ± 2.37 and 1.85 ± 0.28 l·min⁻¹, P < 0.05, vs 2.91 ± 2.01 and 1.27 ± 0.43 l·min⁻¹, P < 0.05. Elimination half-life was 25.4 ± 10.6 and 47.4 ± 5.4 s, P < 0.002 vs 26.3 ± 10.0 and 75.2 ± 21.8 s, P < 0.00005. Conclusion. These results suggest that the rapid disap-pearance of SCh from the circulation is due to diffusion out of the blood vessels rather than to enzymatic hydrolysis. Received for publication on August 31, 1998; accepted on May 11, 1999     

Is median sternotomy invasive? A comparison between minimally invasive direct coronary artery bypass and off-pump bypass

vs 66 ± 8 years old, the operative time, being 321 ± 149 vs 441 ± 205 min, the number of grafts, being 1.0 vs 1.4/patient, peak creatine kinase (CK) values, being 662 ± 436 vs 609 ± 56 IU/l, the peak CK-muscle-brain values, being 12 ± 9 vs 16 ± 5 IU/l, and the postoperative blood loss, being 369 ± 198 vs 541 ± 204 ml. Although there was no significant difference in peak C-reactive protein, at 17 ± 5 vs 20 ± 2 mg/dl, the periods declining within the normal ranges were shorter in the MIDCAB group than in the off-pump group, at 7 ± 1 vs 15 ± 2 days (P > 0.01). The hospital stay was almost the same in both groups, at 16 ± 8 vs 26 ± 14 days. These findings suggest that off-pump bypass is more invasive than MIDCAB, which may be attributed to the median sternotomy. (Received for publication on May 6, 1999; accepted on Jan. 12, 2000)     

Comparison of renal function under deliberate hypotension during epidural plus light-enflurane anesthesia and during enflurane anesthesia

We compared the effects of deliberate hypotension induced with trimethaphan on renal function and renal tubular damage under combined epidural and light-enflurane anesthesia (epidural group) and enflurane anesthesia alone (enflurane group). The mean arterial blood pressure was maintained at 50–55 mm Hg for 2.5 h in both groups using continuous infusion of trimethaphan. The urine volume and free water clearance were significantly greater in the epidural group than in the enflurane group [1.8±1.8 (SD)vs 0.4±0.3 ml·kg⁻¹·h⁻¹ and 0.81±1.30vs −0.15±0.22 ml·min⁻¹, respectively] (P<0.05). The creatinine clearance and fractional sodium excretion rate did not differ significantly between the two groups. Urinary excretion of norepinephrine was significantly less in the epidural group than in the enflurane group (P<0.05); however, epinephrine excretion did not differ. Urinary excretion ofN-acetyl-β-d-glucosaminidase was significantly less in the epidural group than in the enflurane, group (4.2±2.5vs 12.2±4.6 U·g⁻¹ CR) (P<0.01). The plasma antidiuretic hormone concentration was significantly lower in the epidural group compared to the enflurene group (13±23vs 57±42 pg·ml⁻¹) (P<0.05). No significant difference in plasma atrial natriuretic peptide concentration was found between the groups. We conclude that renal function during trimethaphan-induced hypotension is better maintained under epidural plus light-enflurane anesthesia than under enflurane anesthesia alone.     

BILATERAL NEPHRECTOMY DELAYS GASTRIC EMPTYING OF A LIQUID MEAL IN AWAKE RATS

Aims: This study evaluates the effect of bilateral nephrectomy on the gastric emptying of a liquid meal. Methods: Male rats were submitted under anesthesia to cervical vessels cannulation and bilateral lumbar incision, followed or not by nephrectomy. Next day, they were gavage fed (1.5 mL) with phenol red (0.5 gmL^?1) in 5% glucose solution and sacrificed 0, 10, 20, 30 or 45 min later. A blood sample was obtained for biochemical analysis while gastric dye retention was determined by spectrophotometry. Data (mean ± SEM) were compared by ANOVA and Student–Newman–Keuls tests. Results: Gastric emptying values from nephrectomy group at 10, 20, 30 and 45 min were lower (P<0.05) than those of sham-operated animals (22.0 ± 4.0 vs. 38.9 ± 6.1%, 34.1 ± 1.4 vs. 66.9 ± 1.3%, 45.5 ± 6.1 vs. 64.9 ± 5.4% and 59.7 ± 2.4 vs. 81.5 ± 4.0%, respectively). Mean arterial pressure, blood volume, serum osmolarity, urea, creatinine and potassium values were higher (P < 0.05) in nephrectomy group than in sham-operated animals (143.3 ± 2.7 vs. 100.5 ± 4.1 mmHg, 15.7 ± 0.9 vs. 8.9 ± 1.1 mL 100 g^?1, 344.0 ± 10.8 vs. 299.4 ± 1.3 mOsm KgH₂O^?1, 344.0 ± 33.7 vs. 47.0 ± 2.8 mg dL^?1, 3.6 ± 0.3 vs. 1.1 ± 0.1 mg dL^?1, 6.4 ± 0.7 vs. 3.7 ± 0.2 mEq L^?1, respectively). The plasmatic Na⁺ values did not change (139.3 ± 2.0 in sham-operation vs. 123.0 ± 7.5 mEq L^?1 in nephrectomy). Conclusion: Acute loss of kidney function markedly delays the gastric emptying rates, which could be involved in gastrointestinal dysmotility complaints seen after renal failure.     

Insulin-like Growth Factors (IGF) I and II Utilize Different Calcium Signaling Pathways in a Primary Human Parathyroid Cell Culture Model

Background In most cell types, influx of calcium (Ca²⁺) induces a growth or secretory response. The opposite occurs in parathyroid (PTH), cells where there is an inverse relationship between intracellular Ca²⁺ concentration and PTH secretion. We have examined the effects of calcium channel and metabolism modulators on insulin-like growth factors (IGFs) in a parathyroid cell culture model. Methods Cell cultures were prepared from 9 patients undergoing operation for hyperparathyroidism. Following adhesion, the cells were transferred to serum-free medium and dosed with IGF I, II ± ethyleneglycol-bis(β-aminoethyl)-N, N, N′,N′-tetraacetic acid (EGTA), nifedipine, nickel, 2-aminoethoxy-diphenylborate (2-APB), or dantrolene. Proliferation (96 hours) was assessed by measuring tritiated thymidine incorporation and PTH release (1 and 3 hours) assayed by IRMA. Results Both IGF I and II increased DNA synthesis to 162.8% ± 10.6% (SEM) and 131.1% ± 7.7%, respectively (P < 0.05). EGTA at 0.2 mmol (ionized Ca²⁺ 0.2mmol) did not affect the response to both IGFs. EGTA at 2 mmol (ionized Ca²⁺ 0 mmol) reduced the DNA synthesis of IGF I and II to 29% and 26%, respectively (P < 0.05). Nifedipine and nickel (nonspecific Ca²⁺ channel blocker) were equally potent in negating the mitogenic effects of both IGFs. 2-APB (IP₃R blocker) reduced the basal DNA synthesis to 51.3% ± 8.4% but had no effect on either IGF. Dantrolene (ryanodine receptor blocker) negated IGF II induced mitogenisis (74.2% ± 6.7%) and partially inhibited IGF I mitogenesis (123% ± 6%) (P < 0.05). The rate of PTH secretion was greater after IGF II stimulation than after IGF I stimulation. Conclusions IGFs I and II induce mitogenesis by different calcium signaling pathways. These data suggest that parathyroid cells may utilize different calcium signaling pathways to distinguish growth factors and serum calcium changes. An erratum to this article is available at .