Caffeine prevents cholesterol gallstone formation

Methylxanthines are known to inhibit in vitro gallbladder absorption. Increased gallbladder absorption has been observed during formation of cholesterol gallstones. Therefore we tested the hypothesis that caffeine would inhibit in vivo gallbladder absorption and thus prevent formation of cholesterol gallstones. Sixteen adult male prairie dogs received a control nonlithogenic diet, and 16 were fed a diet containing 1.2% cholesterol. Half of the animals in each group received caffeine in their drinking water. Gallbladder and hepatic bile were examined microscopically and analyzed for biliary lipids and electrolytes. The gallbladder/hepatic bile ratios of bile acids and sodium were calculated as indices of gallbladder absorption. All eight animals receiving the 1.2% cholesterol diet formed cholesterol gallstones, whereas none of the eight animals fed the cholesterol diet plus caffeine formed gallstones. The cholesterol saturation index was similar, however, in both groups. In animals fed a control diet, the administration of caffeine significantly increased hepatic bile flow and decreased the gallbladder/hepatic bile ratio for both bile acids (5.4 +/- 0.9 vs 3.6 +/- 0.3; p less than 0.05) and sodium (1.26 +/- 0.03 vs 1.12 +/- 0.03; p less than 0.01). In animals fed the high-cholesterol diet, caffeine significantly decreased the ratios for both bile acids (9.0 +/- 1.6 vs 5.3 +/- 0.6; p less than 0.05) and sodium (1.37 +/- 0.06 vs 1.21 +/- 0.01; p less than 0.05), lowered gallbladder bile protein levels, normalized gallbladder stasis, and lowered serum cholesterol levels. In summary, caffeine prevented formation of cholesterol gallstones in this experimental model. The effect of caffeine may be the result of alterations in multiple biliary parameters including the inhibition of gallbladder absorption.     

胆汁胆固醇对胆囊收缩素受体表达的影响

目的　探讨胆汁胆固醇对胆囊收缩素受体 (CCK R)表达的影响。　方法　采用放射免疫分析法和受体放射配基结合法检测对照组 (n =2 5 )、高胆固醇组 (n =2 5 )、自然恢复组 (n =2 5 )及治疗组 (n =2 5 )豚鼠门静脉血CCK水平、胆囊CCK R的最大结合容量 (Bmax)和亲和力 (Kd) ,同时观察空腹胆囊体积 (FV)、胆囊胆汁量 (FB)和餐后胆囊体积 (RV)、胆囊胆汁量 (RB)及胆囊收缩率 (E)、胆汁胆固醇浓度的变化。　结果　与对照组比较 ,高胆固醇组豚鼠FV[(0 89± 0 2 6 )～ (1 34± 0 6 1)cm3 ]、FB[(0 6 8± 0 2 0 )～ (1 0 1± 0 4 3)cm3 ]、RV[(0 2 8± 0 0 8)～ (0 90± 0 5 3)cm3 ]、RB[(0 2 3± 0 0 6 )～(0 83± 0 32 )cm3 ]增大 ,E[(6 5 83± 7 32 ) %～ (47 2 2± 5 2 4 ) % ]下降 ,胆汁胆固醇浓度 [(0 4 4±0 11)～ (0 6 0± 0 13)mmol/L]升高 ,门静脉血CCK水平及CCK R的Kd无改变 ,而CCK R的Bmax[(6 0± 2 7)～ (32± 13)fmol/mg蛋白 ]下降 ;与自然恢复组比较 ,治疗组上述各项指标正常。　结论　胆汁中的高胆固醇通过下调胆囊CCK R表达而导致胆囊收缩功能障碍 ,降低胆汁高胆固醇浓度可以促进胆囊动力功能的恢复。     

Cod-liver oil in the prevention of intimal hyperplasia in autogenous vein grafts used for arterial bypass

Cod-liver oil, rich in eicosapentaenoic acid, an unsaturated fatty acid, was administered to 14 mongrel dogs to determine if this acid would prevent platelet-mediated intimal hyperplasia. Twenty-eight 1 cm segments of undistended jugular vein were interposed between bilaterally divided femoral arteries. Seven control animals were fed a 2% cholesterol diet 1 week before and for 6 weeks after the operation. A further seven animals received cod-liver oil capsules containing 1.8 gm of eicosapentaenoic acid daily 1 week before and for 6 weeks after autogenous vein implantation, in addition to the lipid-supplemented diet. Baseline serum cholesterol was 4.6 +/- 0.4 mmol/L. The rise in serum cholesterol was similar in the two groups and increased to 7.4 +/- 0.6 mmol/L (control group) and to 6.8 +/- 0.2 mmol/L (eicosapentaenoic acid group) (p less than 0.001). Prothrombin time, partial thromboplastin time, bleeding time, and platelet counts were unchanged in the two groups. Vein grafts, harvested at 6 weeks, were fixed in formaldehyde. Mean intimal thickness was measured from multiple vein graft cross sections with a Zeiss computerized interactive image analyzing system. A mean of 140 +/- 11 measurements were computed from each graft. Marked intimal hyperplasia occurred in the control group and increased from 4.3 +/- 0.3 to 86.4 +/- 14 micron. In contrast, a high eicosapentaenoic acid diet inhibited intimal hyperplasia, with intimal thickness only increasing from 4.0 +/- 0.4 to 24.8 +/- 2.7 micron (p less than 0.001). These data indicate that eicosapentaenoic acid inhibits platelet-mediated intimal hyperplasia and suggest that cod-liver oil could be used to prevent intimal hyperplasia in vein grafts used for myocardial revascularization.     

Effect of bile diversion and sphincterotomy on gallbladder muscle contractility and gallstone formation

Feeding prairie dogs a diet rich in cholesterol induces gallstone formation that is preceded by a sustained decrease in gallbladder smooth muscle contractility. Sphincterotomy is known to prevent gallstone formation in cholesterol-fed prairie dogs. Experiments were designed to determine whether the effect of sphincterotomy is a consequence of hepatic bile diversion, and whether bile diversion prevents the altered contractility. Following sham operation, surgical biliary enteric bypass, or sphincterotomy, prairie dogs were fed a high-cholesterol or a regular diet. Gallbladder muscle contractility and the presence of crystals and stones were determined. In sham-operated animals, the cholesterol diet induced a decrease in gallbladder muscle contractility and caused the formation of cholesterol gallstones. In animals with bile diversion and sphincterotomy, the effects of cholesterol feeding were reduced or prevented. Thus, these procedures may prevent stone formation by preventing a reduction in gallbladder contractility. Contractility was depressed in animals with bile diversion fed a regular diet, compared with animals with a sham operation fed a regular diet. The mechanism for this depression may differ from that induced by the cholesterol diet. Diversion, and perhaps sphincterotomy, impairs gallbladder filling. Thus, gallbladder muscle is not stretched and does not contract against a load. This could result in a "disuse atrophy." If the results from our study apply to humans, sphincterotomy may reduce stone formation by preventing the effects of lithogenic bile on gallbladder muscle contractility and by enhancing the ability of the muscle to empty the lithogenic bile.     

Nonalcoholic fatty gallbladder disease: The influence of diet in lean and obese mice

The obesity epidemic has contributed to an increased prevalence of gallstones and a higher percentage of chronic acalculous cholecystitis. Obesity is associated with Type II diabetes and hyperlipidemia in murine models. In addition, we have previously demonstrated that serum glucose, insulin, cholesterol, and triglycerides correlated with gallbladder contractility in murine models. However, the relative role of in sulin resistance and gallbladder fat infiltration in this phenomenon remain unclear. Therefore, we tested the hypothesis that gallbladder wall lipids are related to obesity and diet and are inversely correlated with gallbladder contractility. One hundred lean control (C7BL/6J) and 36 obese leptin-deficient (Lep^ob) 8-week-old female mice were fed either a chow diet or a 1.0% cholesterol, 15% butterfat (high-lipid) diet for four weeks. Pooled gallbladders were then analyzed for free fatty acids (FFA), phospholipids (PL), total cholesterol (TC), and triglycerides (TG). Cholesterol/phospholipid ratios were then calculated. The Lepob mice fed a chow diet had significantly higher (P<0.01) gallbladder lipids than the three other groups. The lean mice that were fed a high-lipid diet had increased (P<0.05) gallbladder TC compared to the lean mice on a chow diet. In addition, the cholesterol/phospholipid ratio was significantly in creased (P<0.01) in the lean mice fed a high-lipid diet compared to the other three groups. Finally, the high-lipid diet decreased gallbladder FFA (P<0.01), PL (P=0.08), and TC (P<0.05) in Lep^ob mice. These data suggest that (1) obese mice have increased gallbladder lipids; (2) a high-cholesterol, high-fat diet increases gallbladder lipids and the cholesterol/phospholipid ratio in lean mice; but (3) de creases gallbladder fatty acids, phospholipids, and cholesterol in obese mice. Prior studies have docu mented similarly decreased gallbladder response to neurotransmitters in obese mice on a chow diet, as well as lean and obese mice on a high-lipid diet. Therefore, we conclude that leptin-deficient obesity and/or a high-fat diet causes nonalcoholic fatty gallbladder disease, which is manifested by diminished gallbladder contractility. Presented at the 2005 American Hepato-Pancreato-Biliary Association Congress, Hollywood, Florida, April 14–17, 2005. Supported by NIH grant R-01 DK44279.     

Correction of enhanced endothelial permeability by cessation of cholesterol feeding

Changes in endothelial permeability and the transport of macromolecules may be important in the initiation and/or progression of atherosclerosis. We have previously shown, with a carotid artery preparation isolated in situ with intact adventitia, that long-term cholesterol feeding in rabbits will result in a seven- to tenfold increase in 125I albumin transport across the artery into the systemic circulation. The current studies were undertaken to determine whether this abnormality of enhanced permeability could be reversed by cessation of cholesterol feeding and correction of the hyperlipidemia. Two groups of rabbits were fed either a standard Rabbit Chow or a diet containing 1.5% cholesterol and 5.2% corn oil for 12 to 15 weeks. Another group of rabbits was given cholesterol for 12 to 15 weeks with change to standard rabbit chow for an additional 22 to 24 weeks after which albumin transport studies were then performed. Mean plasma cholesterol level after 12 to 15 weeks of cholesterol feeding was 2052 +/- 395 mg/dl. After the animals were withdrawn from the cholesterol diet for 22 to 24 weeks, the mean plasma cholesterol level decreased to 80 +/- 21 mg/dl. The mean plasma cholesterol value in chow-fed animals was 39 +/- 6 mg/dl. Perfusion studies were done with 125I-labeled albumin and plasma radioactivity served as a measure of transport across the carotid artery. The average level of albumin transport across the artery into venous blood in the cholesterol-fed animals (13,911 dpm/ml of plasma) was significantly greater than that of control animals (2049 dpm/ml of plasma).(ABSTRACT TRUNCATED AT 250 WORDS)     

Bilirubin monoglucuronide promotes cholesterol gallstone formation

Recent evidence suggests that cholesterol (Ch) solubility in bile is determined by a complex interaction of mixed micelles and lecithin-cholesterol vesicles. Bilirubin monoglucuronide (BMG), which binds to bile salts and incorporates into mixed micelles, may displace cholesterol from micelles into vesicles, thus favoring cholesterol monohydrate crystal precipitation. Therefore, we designed an experiment to test the hypothesis that BMG may enhance cholesterol gallstone formation without inducing cholesterol supersaturation. For 8 weeks, 28 adult male prairie dogs were fed either a control, nonlithogenic diet (0.03% Ch), a high carbohydrate diet (CHO) which has no cholesterol but increases hepatic bilirubin secretion, or the same CHO diet plus 0.03% Ch. Cholecystectomy was then performed, and bile was examined microscopically for stones or crystals and analyzed for BMG and biliary lipids. Cholesterol saturation index was calculated. Cholesterol gallstones were found in none of the control animals and in 13% of the CHO-fed animals. However, the addition of trace cholesterol to the CHO diet resulted in an 88% incidence of cholesterol gallstones (P less than 0.001 vs control, P less than 0.01 vs CHO, respectively). Gallbladder bile was unsaturated with cholesterol in all groups. (control = 0.65 +/- 0.05, CHO = 0.46 +/- 0.05, CHO + 0.03% Ch = 0.70 +/- 0.03). CHO feeding alone or with trace cholesterol significantly elevated gallbladder bilirubin monoglucuronide, phospholipid, and cholesterol concentrations when compared to controls. These data suggest that in the prairie dog a high carbohydrate diet with only trace amounts of cholesterol increases bilirubin monoglucuronide in gallbladder bile and causes cholesterol gallstone formation without inducing cholesterol supersaturation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of dietary ethanol on gallbladder absorption and cholesterol gallstone formation in the prairie dog

Dietary ethanol has been reported to protect against cholesterol gallstone formation. Because enhanced gallbladder absorption of water is important in cholesterol cholelithiasis, we examined the hypothesis that ethanol acts by inhibiting the absorptive function of the gallbladder. Eighteen adult male prairie dogs were fed a lithogenic liquid diet containing 0.4% cholesterol. Half of the animals received 30% of total calories as ethanol, whereas their pair-fed controls received equicaloric amounts of maltose-dextrin. After 3 months, the gallbladders were inspected for gallstones and crystals, and gallbladder and hepatic bile were analyzed. Cholesterol stones and crystals were present in all nine controls. None of the alcohol-fed animals had stones, but four had cholesterol crystals. Gallbladder cholesterol, phospholipids, and total calcium were significantly decreased in alcohol-fed animals. In both gallbladder and hepatic bile, the cholesterol saturation index was significantly lower in alcohol-fed animals, as was the ratio of trihydroxy to dihydroxy bile salts. The ethanol-supplemented diet produced a significant decrease in the absorption of water by the gallbladder as indicated by changes in the gallbladder bile to hepatic bile ratios of the total bile salt concentration (7.29 +/- 1.25 versus 3.84 +/- 0.56; p less than 0.05) and the total calcium (3.37 +/- 0.24 versus 2.43 +/- 0.29; p less than 0.05). These findings indicate that the protective effect of ethanol may be related to its ability both to inhibit gallbladder absorption of water and to alter the composition of biliary lipids.     

Iron deficiency transiently suppresses biliary neuronal nitric oxide synthase

BACKGROUND: Iron deficiency results in altered gallbladder and sphincter of Oddi (SO) motility and cholesterol crystal formation. In addition, gallbladder neuronal nitric oxide synthase (nNOS) has been shown to be markedly reduced after 8 weeks on an iron-deficient diet. However, the effects of prolonged iron deficiency on gallbladder and SO nNOS as well as crystal formation have not been determined. Therefore, we tested the hypothesis that iron deficiency would downregulate both gallbladder and SO nNOS expression and that nNOS downregulation and cholesterol crystal formation would progress over time. MATERIALS AND METHODS: Thirty-eight adult female prairie dogs were fed either an ironsupplemented (Fe+) (200 ppm) or an iron-deficient (Fe-) (8 ppm) diet for 8 weeks (Fe+ n = 9, Fe- n = 10) or 16 weeks (Fe+ n = 9, Fe- n = 10). Blood hemoglobin (HbG) was measured; gallbladder cholesterol crystals were counted; and cholesterol saturation indices (CSI) were calculated. Gallbladder and SO nNOS levels were measured by Western blot. RESULTS: The Fe+ prairie dogs had significantly higher HbG than the Fe- animals (16.9 +/- 0.6 g/dl vs 15.2 +/- 0.5 g/dl, respectively, P < 0.05) after 8 weeks. This difference was even greater after 16 weeks (16.1 +/- 0.4 g/dl vs 14.0 +/- 0.5 g/dl, P < 0.01). At 8 weeks, more cholesterol crystals per 10 HPF were observed in the Fe- animals (0.4 +/- 0.3 vs 1.6 +/- 0.4 per 10 HPF, P < 0.05). This difference was even greater after 16 weeks (0.0 +/- 0.0 vs 52.6 +/- 25.3 per 10 HPF, P < 0.01). No difference in the CSI was observed in the four groups. Iron deficiency decreased the nNOS/beta-actin protein levels in the gallbladder and SO at 8 weeks (57.0 +/- 29.6 vs 7.4 +/- 2.6, gallbladder, P < 0.05) (98.4 +/- 39.7 vs 29.9 +/- 11.0, SO, P = 0.09), but these levels returned to baseline at 16 weeks. CONCLUSIONS: We conclude that iron deficiency acutely suppresses gallbladder and SO nNOS, and that compensatory mechanisms return nNOS to baseline levels while cholesterol crystal formation increases over time.     

Dietary marine oil supplements fail to affect cholesterol metabolism or inhibit atherosclerosis in rabbits with diet-induced hypercholesterolemia

Dietary marine oil supplements may protect against atherosclerosis, although their influence on plasma lipids, in vivo cholesterol metabolism, and aortic cholesterol accumulation remains uncertain. The effects of daily administration of marine oil--delivering 100 mg of eicosapentaenoic acid, 59 mg of docosahexaenoic acid, and 221 mg of omega-3 fatty acids per kilogram--were assessed in 33 New Zealand white rabbits. Six animals (group I) were immediately killed. In the remaining animals stable hypercholesterolemia was induced with a 0.25% cholesterol-enriched diet. After 7 weeks on this diet, six animals were killed (group II). Total plasma cholesterol had increased significantly (982 +/- 119 mg/dl vs. 55.6 +/- 7.1 mg/dl, mean +/- SEM, p less than 0.001). The remaining animals randomly received a tap-water placebo (group III, n = 12) or marine oil (group IV, n = 9) daily. After 3 months, total plasma cholesterol was similar (p = NS) among group II (982 +/- 119 mg/dl), group III (965 +/- 54 mg/dl), and group IV (913 +/- 46 mg/dl). No significant differences in HDL cholesterol, LDL cholesterol, VLDL cholesterol, or triglyceride levels developed between the placebo and marine oil groups. Two-hour, hepatic total lipid, neutral steroid, fatty acid, bile acid, and cholesterol synthesis rates were not significantly affected by marine oil treatment. Thoracic aortic cholesterol content increased during cholesterol feeding (5.7 +/- 0.9 mg/gm vs. 1.1 +/- 0.05 mg/gm, group II vs. group I, p less than 0.05). Marine oil supplementation had no effect on the progressive accumulation of cholesterol in the thoracic aorta (28.8 +/- 2.5 mg/gm vs. 29.4 +/- 1.8 mg/gm, group IV vs. group III, p = 0.84). The abdominal aortic cholesterol contents were also similar. These results do not support the use of dietary marine oil supplements for the amelioration of lipid metabolism or the prevention of atherosclerosis.     

Steatocholecystitis: the influence of obesity and dietary carbohydrates

INTRODUCTION: We have recently demonstrated that obese and lean mice fed a high fat diet have increased gallbladder wall fat and decreased gallbladder contractility, cholecystosteatosis. Animal and human data also suggest that diets high in refined carbohydrates lead to gallstone formation. However, no data are available on the role of dietary carbohydrates on gallbladder wall fat and inflammation. Therefore, we tested the hypothesis that both obesity and dietary carbohydrates would increase gallbladder fat and cytokines, steatocholecystitis. METHODS: At 8 wk of age, 47 lean and 22 obese female mice were fed a 45% carbohydrate (CHO) diet while an equal number of lean and obese mice were fed a 75% CHO diet for 4 wk. All mice underwent cholecystectomy, and the gallbladders were snap-frozen. Individual and total lipids were measured by gas chromatography. Interleukin (IL)-1beta, tumor necrosis factor (TNF)-alpha, and IL-6 were measured by enzyme-linked immunosorbent assay. Data were analyzed by analysis of variance and Tukey test. RESULTS: Gallbladder total fat, triglycerides, and cholesterol were maximum (P < 0.001) in obese mice on the 75% CHO diet. Gallbladder TNF-alpha and IL-1beta as well as serum cholesterol levels showed a similar pattern (P < 0.001). Gallbladder saturated free fatty acids and IL-6 levels were highest (P < 0.001) in obese mice on the 45% CHO diet. CONCLUSIONS: These data suggest that (1) both obesity and dietary carbohydrates increase gallbladder total fat, triglycerides, cholesterol, TNF-alpha, and IL-1beta and (2) obesity also increases gallbladder free fatty acids and IL-6. Therefore, we conclude that obesity is associated with steatocholecystitis and that a high carbohydrate diet exacerbates this phenomenon.     

Diabetes and hyperlipidemia correlate with gallbladder contractility in leptin-related murine obesity

Obesity is associated with many comorbid conditions including diabetes, hyperlipidemia, and gallstones. However, the interaction among these modalities remains unclear. We recently demonstrated that both leptin-deficient and leptin-resistant obese mice have impaired biliary motility. These obese mice also are diabetic and hyperlipidemic. Therefore, we tested the hypothesis that serum glucose, insulin, cholesterol, and triglyceride levels would correlate with gallbladder contractility. Thirty-four lean control, 10 lean heterozygous leptin-deficient, 18 obese homozygous leptin-deficient, and 12 obese homozygous leptin-resistant mice were fed a nonlithogenic chow diet while nine lean control and nine obese homozygous leptin-deficient mice were fed a high-cholesterol diet for 4 weeks. In vitro gallbladder responses to cholecystokinin (CCK; 10^-8 mol/L), acetylcholine (ACh; 10^-5 mol/L), and neuropeptide Y (NPY; 10^-6 mol/L) were measured. Serum glucose, insulin, cholesterol, and triglyceride levels were measured from pooled serum from an additional 704 animals. Gallbladder responses were greatest for CCK, intermediate for ACh, and least for NPY. Serum glucose, insulin, cholesterol, and triglyceride levels and body weight all correlated similarly, negatively, and significantly (P < 0.001) with gallbladder contractility. Hyperglycemia, insulin-resistance, hyperlipidemia, and body weight in obese mice with leptin dysfunction are associated with poor gallbladder contractility, which in turn may contribute to the association between obesity and gallstone formation. Presented in part at Digestive Disease Week 2003, SSAT Plenary Session and Residents’ Conference, Orlando, Florida, May 17–22, 2003 (oral presentation); and at the Association for Academic Surgery, Poster Session, Boston, Massachusetts, November 7–9, 2002. Supported by grant NIH R-01 DK44279 from the National Institutes of Health.     

Long-term function of human cardiac allografts assessed by two-dimensional echocardiography

Previous studies from our laboratory demonstrated increasing left ventricular mass in cyclosporine-treated cardiac allograft recipients over 30 days after transplantation, but the long-term evolution of this process and possible effects on allograft function are unknown. Accordingly, quantitative two-dimensional echocardiography was performed 2 and 23 days and 15 months postoperatively in 14 recipients treated with cyclosporine and prednisone. Changes in left ventricular ejection fraction, end-diastolic volume, mass, and end-systolic wall stress were analyzed. Comparison of studies at 2 and 23 days revealed significant (p less than 0.01) increases in ejection fraction (54% +/- 8% [standard deviation] to 62% +/- 4%), end-diastolic volume (84% +/- 32 ml to 96 +/- 31 ml), and left ventricular mass (118 +/- 45 gm to 136 +/- 41 gm). Comparison of studies at 23 days and 15 months revealed no significant change in end-diastolic volume or left ventricular mass, whereas ejection fraction decreased slightly (62% +/- 4% to 57% +/- 4%, p less than 0.01). End-systolic wall stress decreased when data at 2 days and 15 months were compared (83 +/- 24 gm/cm2 versus 66 +/- 18 gm/cm2, p less than 0.05), but no change in contractility was apparent from the ejection fraction/end-systolic stress relation. We conclude that left ventricular mass and end-diastolic volume increase early after transplantation in cyclosporine-treated cardiac allograft recipients, but these changes are not predictive of long-term results, which are characterized by no significant late variation in left ventricular mass, end-diastolic volume, or contractility.     

The role of aspirin and dipyridamole on vascular DNA synthesis and intimal hyperplasia following deendothelialization

Platelets are implicated both in acute thrombotic events and, through platelet-derived growth factor, in the development of intimal hyperplasia. We have investigated, in vivo, the influence of aspirin and dipyridamole on vascular smooth muscle cell proliferation and DNA synthesis following balloon catheter injury. Fifty-eight male, New Zealand white rabbits were divided equally into two groups; the test group was fed aspirin (14 mg/kg/day) and dipyridamole (9 mg/kg/day) from 2 days prior to surgery until sacrifice at 1, 2, 3, 4, 7, 14, or 28 days after injury. All animals were sacrificed 1 h after injection of [3H]thymidine and the smooth muscle cell DNA specific activity and total kinetic activity were determined. Intimal hyperplasia was measured by light microscopy and intimal nuclear proliferation was determined by counting nuclei per millimeter of internal elastic lamina. Nuclear proliferation was maximal at 14 days (25 +/- 1.2) but intimal hyperplasia was still increasing at 28 days. DNA specific activity after 24 hr (test: 4 +/- 2 dpm/micrograms DNA; control: 3.3 +/- 3 dpm/micrograms DNA) was similar to basal levels in uninjured rabbits. DNA synthesis peaked in both groups between the second and third day (test: 177 +/- 27 dpm/micrograms DNA; control: 185 +/- 39 dpm/micrograms DNA) and then declined slowly toward baseline values. There was no significant difference between treated and normal rabbits in either [3H]thymidine incorporation, nuclear proliferation, or development of intimal hyperplasia despite 90% inhibition of platelet aggregation and a significant reduction (78%) in [14C]serotonin release following collagen challenge (6 micrograms/ml).(ABSTRACT TRUNCATED AT 250 WORDS)     

Ileal resection-induced gallstones: altered bilirubin or cholesterol metabolism?

Ileal resection has been shown to increase the risk of cholelithiasis. Earlier studies in humans suggested that ileal resection increases the cholesterol saturation index. Recent data from patients on long-term parenteral nutrition and from animals, however, have suggested that ileal resection predisposes to pigment gallstone formation. We therefore tested the hypothesis that ileal resection alters bile calcium and bilirubin metabolism without affecting the cholesterol saturation index. Adult male prairie dogs underwent either sham laparotomy (eight prairie dogs) or ileal resection (16 prairie dogs). All animals were fed a trace cholesterol (nonlithogenic) diet before and for 4 weeks after operation. Pigment gallstones were present in 44% of the ileal-resected animals and in none of the sham animals (p less than 0.05). Calcium bilirubinate crystals were present in 94% of the ileal-resected animals and in none of the sham animals (p less than 0.01). Gallbladder bile calcium (25.6 +/- 2.4 versus 17.2 +/- 1.1 mg/dl; p less than 0.05) and total bilirubin (29.3 +/- 4.0 versus 9.4 +/- 1.8 mg/dl; p less than 0.01) concentrations were significantly greater in ileal-resected animals. The cholesterol saturation index of gallbladder bile, however, was no different in ileal-resected (0.53 +/- 0.04) and in sham-operated animals (0.50 +/- 0.04). Although initial studies suggested that the cholesterol saturation index of hepatic bile was increased after ileal resection, a second set of experiments demonstrated that this phenomenon resulted from washout of bile salts that were already in extremely low concentrations in hepatic bile. We conclude that alterations in bilirubin, but not cholesterol, metabolism result in pigment gallstone formation after ileal resection.     

The effects of dimethyl sulfoxide on aortic prostacyclin production and serum thromboxane and plasma fibrinogen levels in rabbits fed a normal versus a cholesterol-enriched diet

Through an unknown mechanism, dimethyl sulfoxide (DMSO) retards atherogenesis in cholesterol-fed rabbits (CFR). We studied the effects on the development of lesions and prostacyclin (PGI2) production in the thoracic aorta and total serum lipid and cholesterol content of the abdominal aortic serum thromboxane (TXB2) and plasma fibrinogen levels in rabbits fed control versus atherogenic diets, with and without DMSO. Without DMSO, PGI2 production was significantly higher in CFR versus control animals (8.65 +/- 1.0 vs 6.38 +/- 0.3 ng/15 min [p less than 0.02]). DMSO did not influence PGI2 production in any of the groups but significantly reduced the number of atheromatous lesions in CFR (78% +/- 9% vs 8% +/- 4% [p less than 0.001]). With DMSO, CFR had a significant reduction in total lipid levels (422 +/- 5 vs 300 +/- 21 mg/gm dry wt [p less than 0.01]) and cholesterol levels (74 +/- 12.8 vs 31.8 +/- 6.4 mg/gm dry wt [p less than 0.01]) compared with control animals. Fibrinogen levels were significantly lower in CFR versus control animals (0.83 +/- 0.07 vs 2.42 +/- 0.13 mg/ml [p less than 0.01]). TXB2 was lower in DMSO plus control versus control animals alone. In conclusion, DMSO does not appear to act through changes in PGI2 or fibrinogen activity. Its effect in lowering TXB2 in CFR suggests an action on platelet function.     

Comparison of cod-liver oil and aspirin-dipyridamole for the prevention of intimal hyperplasia in autologous vein grafts

The combination of aspirin and dipyridamole is currently used to prevent intimal hyperplasia and to improve long-term vein graft patency following myocardial revascularization. Preliminary studies indicate that cod-liver oil, rich in eicosapentaenoic acid, an unsaturated fatty acid, may also be effective in the prevention of intimal hyperplasia. Twenty-four mongrel dogs were used to compare the effectiveness of aspirin-dipyridamole and cod-liver oil on vein graft intimal hyperplasia following arterial bypass. Forty-eight segments of undistended autologous external jugular vein were interposed between bilaterally divided femoral arteries. All animals received a 2% cholesterol diet for 1 week before and 6 weeks after operation. Eight controls received the diet alone. Eight other animals received dipyridamole (2.5 mg per kilogram of body weight) two days before operation and dipyridamole (2.5 mg/kg) and aspirin (30 mg/kg) daily for 6 weeks after operation. Another 8 animals received cod-liver oil containing 1.8 gm of eicosapentaenoic acid daily 1 week before and for 6 weeks following operation. Serum cholesterol increased similarly in all groups; it rose from 4.5 +/- 0.2 mm/L to 8.3 +/- 0.8 mm/L in the controls, to 7.2 +/- 0.5 mm/L in the aspirin-dipyridamole group, and to 7.1 +/- 0.5 mm/L in the cod-liver oil group (p less than 0.01). Prothrombin time, partial thromoboplastin time, total platelet counts, and bleeding times were unchanged. Intimal hyperplasia was measured at 6 weeks with a Zeiss computerized microscope; 376 +/- 25 measurements were made from each graft. The intima increased from 4.5 +/- 0.2 to 83 +/- 10 micron in the control dogs.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of a Chinese herbal medicine mixture on a rat model of hypercholesterolemic erectile dysfunction

PURPOSE: We examine the effect of a Chinese herbal medicine mixture on erectile function in a rat model of hypercholesterolemic erectile dysfunction. MATERIALS AND METHODS: In this study 32, 3-month-old Sprague-Dawley rats were used. The 8 control animals were fed a normal diet and the remaining 24 were fed 1% cholesterol diet for 4 months. After 2 months herbal medicine was added to the drinking water of the treatment group of 16 rats but not the cholesterol only group of 8. Of the 16 rats 8 received 25 mg./kg. per day (group 1) and 8 received 50 mg./kg. per day (group 2) of Chinese herbal medicine mixture. Serum cholesterol levels were measured at 2 and 4 months. At 4 months erectile function was evaluated with cavernous nerve electrostimulation in all animals. Penile tissues were collected for electron microscopy, and to perform Western blot for endothelial nitric oxide synthase, neuronal nitric oxide synthase, basic fibroblast growth factor (bFGF) and caveolin-1. RESULTS: Serum cholesterol levels were significantly higher in animals fed the 1% cholesterol diet compared to controls at 2 and 4 months. Nevertheless, there was no significant difference among group 1 (145 +/- 30 mg./dl.), group 2 (157 +/- 20) and the cholesterol only group (143 +/- 15). Systemic arterial pressure was not significantly different between the animals that were fed the 1% cholesterol diet and the controls. During electrostimulation of the cavernous nerve peak sustained intracavernous pressure was significantly lower in the cholesterol only group (50 +/- 23 cm. H2O) compared to the control group. Conversely erectile function was not impaired in the herbal medicine treated rats. Electron microscopy showed many caveolae with fingerlike processes in the cavernous smooth muscle and endothelial cell membranes in control and treated rats but not in the cholesterol only group of rats. Western blot did not show a difference among groups in protein expression for endothelial nitric oxide synthase and neuronal nitric oxide synthase in penile tissue but caveolin-1 and bFGF protein expression was significantly higher in groups 1 and 2 than in the cholesterol only and control groups. CONCLUSIONS: Rats developed erectile dysfunction after being fed a 1% cholesterol diet for 4 months. Although serum cholesterol levels were similar in the cholesterol only rats and those treated with Chinese herbal medicine mixture, erectile response was significantly better in the treated group. The mechanism of the herbal medicine is unknown. High levels of bFGF and caveolin-1 expression in the treated group may protect the cavernous smooth muscle and endothelial cells from the harmful effect of high serum cholesterol.     

Aerodynamic evaluation of crystalloid and colloid flush perfusion for lung preservation

To assess the effectiveness of pulmonary perfusion we evaluated the lung mechanics of 36 canine lungs in an isolated perfused working lung (IPWL) model. Four groups of lungs (n = 9 each) were preserved by pulmonary artery flushing with either high-potassium colloid (UW), high-potassium crystalloid (EuroCollins', EC), low-potassium crystalloid control (lactate), or low-potassium substrate-enhanced crystalloid (RPMI) followed by 130 +/- 10 min of cold storage. Ventilation remained constant (TV 10 ml/kg at 14 breaths/min with 5 cm H2O PEEP). Assessed data included lung resistance (R), timed expiratory volume (EV0.3 sec as %TV), lung compliance (C), elastic work (Wel), and flow-resistive work (Wres). Immediately following storage, R and Wel were similar for all groups (16 +/- 3 cm H2O/liter/sec and 149 +/- 18 gm/min). UW preserved lungs were less compliant (1.5 +/- 0.1 X 10(-2) liter/cm H2O) and required more inspiratory work (Wres 5.8 +/- 0.8 gm/min) compared to the low-potassium crystalloid (Lactate) group (2.0 +/- 0.1 X 10(-2) liter/cm H2O and 3.4 +/- 0.6 gm/min, respectively, P less than 0.05). For 3 hr of reperfusion, crystalloid lungs showed no significant change in R, C, Wel, or Wres. In contrast, R of the UW group increased significantly to 32 +/- 5 and 40 +/- 8 cmH2O/liter/sec at 1 and 3 hr, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Role of gallbladder mucus in the pathogenesis of cholesterol gallstones

Recent observations indicate that the hepatic secretion of lithogenic bile, gallbladder mucus hypersection, and gallbladder stasis are all critical factors in the pathogenesis of cholesterol gallstones. Using the prairie dog gallstone model, we investigated the interaction of these factors and the sequence in which they develop. The results of this study indicated that (1) gallbladder bile mucus concentration is elevated before cholesterol precipitation and increases progressively with the formation of cholesterol crystals, (2) cystic duct resistance increases in the presence of cholesterol crystals, but not fine, sonicated crystals increase cystic duct resistance. We conclude that these alterations trigger a self-perpetuating cycle of mucus hypersecretion, cholesterol crystallization, and gallbladder stasis which culminates in the formation of cholesterol gallstones.