Effect of ethynylestradiol on biliary excretion of bile acids, phosphatidylcolines, and cholesterol in the bile fistula rat

The effects of ethynylestradiol on endogenous bile acids, their capacity to conjugate and excrete intravenously infused cholic acid, the concentrations of biliary cholesterol and lecithin, and the individual molecular species of phosphatidylcholine have been determined in male and female Sprague-Dawley rats. Endogenous biliary bile acids were analyzed by gas-liquid chromatography-mass spectrometry. Eleven bile acids were identified and several minor bile acids, primarily muricholates, could not be completely characterized. After 5 days of treatment with ethynylestradiol (1 mg/kg per day), the percentage of cholic acid decreased and the percentage of 6beta-hydroxylated bile acids, including several monounsaturated species, increased. Ethynylestradiol caused a decrease in bile acid-independent bile flow. Intravenous infusion of cholic acid at a high concentration caused cholestasis in control animals but, after ethynylestradiol treatment, cholestasis developed during the infusion of a much lower concentration of cholate, indicating a lowered threshhold for bile acid-induced cholestasis. In the treated rats, there was a slight increase in excretion of unconjugated endogenous bile acids, and a striking impairment of conjugation of intravenously administered cholic acid. One of the few sex-related differences observed was an increased concentration of biliary phospholipids in untreated male rats. Both phospholipid and cholesterol concentrations in the bile were higher in the treated animals. The molar percentage of cholesterol was always 1-2%, but it was slightly higher in treated animals, especially males. Ethynylestradiol treatment also affected biliary phospholipid by causing a marked increase of phosphatidylcholine species containing palmitic and oleic acid residues and a decrease of species containing stearic and linoleic acid residues. There was no increase in biliary excretion of long chain polyunsaturated species, which might have indicated damage to membranes, in response to ethynylestradiol either alone or with cholic acid infusion. Some of these ethynylestradiol-induced changes in biliary bile acid and lipid excretion are probably peculiar to the rat, but others, such as the increase in molar percentage of cholesterol and cholestasis, may be relevant to disorders in man, especially cholesterol gallstones and idiopathic cholestasis of pregnancy.     

Lipid composition of bile in morbid obesity before and after jejunoileal bypass surgery

Bile cholesterol, phospholipids, total bile acids, individual bile acids, and fatty acid compositions of bile neutral lipids and phospholipids were analyzed before, at one month and at six months following jejunoileal bypass surgery in a series of morbidly obese patients. Preoperative mole percentages of cholesterol and lithogenic indices were high, indicating that biles were supersaturated with cholesterol and outside the micellar solubility zone when plotted on triangular coordinates. At the one month post-operative period percentages of cholesterol and lithogenic indices were significantly increased as compared to the pre-operative state. At six months post-operatively these values had decreased to approximately the pre-operative levels. No changes were observed in percentages of lithocholic acid, but deoxycholic acid decreased to markedly low levels at one month and remained low at the six month post-operative interval. Relative proportions of cholic acid increased, and the ratio of cholic to chenodeoxycholic acid was significantly increased at both post-operative intervals. No significant changes were noted in bile neutral lipid or phospholipid fatty acid composition, indicating that no depletion of essential fatty acids had occurred.     

Dietary linoleic acid increases and palmitic acid decreases hepatic LDL receptor protein and mRNA abundance in young pigs

The present study was conducted to determine the effects of dietary fatty acids on hepatic LDL receptor (LDLr) protein abundance and mRNA levels. Sixty pigs were randomized into 10 groups and fed corn-soybean meal diets containing three cholesterol levels (0.25%, 0.5%, and 1.0%, w/w) with no added fat, or fats rich (30% of calories) in palmitic acid or linoleic acid. A control group was fed the base diet with no added fat. After 30 days, plasma LDL-cholesterol (LDL-C) levels increased as the dietary cholesterol increased (P < 0.05); however, there was no significant effect of either fatty acid. Dietary fatty acids, however, had distinctly different effects on hepatic LDLr protein (analyzed by ELISA) and mRNA (analyzed by Northern blot) abundance. When pigs consumed diets containing 0.25% cholesterol, linoleic acid increased hepatic LDLr protein 40% whereas palmitic acid reduced it 40% (P < 0.05). These changes in LDLr protein abundance were accompanied by parallel changes in hepatic LDLr mRNA; linoleic acid increased LDLr mRNA 2-fold (P < 0.01), whereas palmitic acid decreased it 60% (P < 0.01). The differential effects of fatty acids on LDLr expression were only observed at 0.25% cholesterol, suggesting that higher intakes of cholesterol have a dominant and repressive effect on regulation of LDLr expression. Cholesterol intake increased hepatic total cholesterol levels (P < 0.01) while dietary fatty acids had no effect on hepatic sterols. In summary, our results indicate that dietary linoleic acid and palmitic acid have markedly different effects on hepatic LDLr protein abundance that are mediated by differential effects on LDLr mRNA and protein levels. Further studies are needed to fully elucidate the molecular mechanisms by which fatty acids regulate LDLr mRNA and protein levels.     

The effect of a free radical scavenger and platelet-activating factor antagonist on FFA accumulation in post-ischemic canine brain

The effects of the platelet-activating factor antagonist BN 50739 and a free radical scavenger dimethyl sulfoxide on the accumulation of free fatty acids in post-ischemic canine brain are reported. Following 14 min of complete normothermic ischemia and 60 min of reperfusion, the total brain FFAs were approximately 150% higher than in the control group (p < 0.05). Perfusion with the platelet-activating factor antagonist BN50739 in its diluent dimethyl sulfoxide during 60 min of post-ischemic reoxygenation resulted in a 61.8% (p < 0.01) reduction in the total brain free fatty acid accumulation. Palmitic, stearic, oleic, linoleic, and arachidonic acids decreased by 53.8%, 63.5%, 69.0%, 47.4%, and 57.2%, respectively. Although dimethyl sulfoxide alone caused stearic and arachidonic acids to return to the normal concentration range, BN 50739 had a significant influence on recovery of palmitic, oleic, and linoleic acids and was previously shown to provide significant therapeutic protection against damage to brain mitochondria following an ischemic episode. Because free fatty acid accumulation is one of the early phenomena in cerebral ischemia, this study provides evidence to support the hypothesis that both platelet-activating factor and free radicals are involved in initiating cerebral ischemic injury.     

Cholelithiasis in Taiwan. Gallstone characteristics, surgical incidence, bile lipid composition, and role of beta-glucuronidase

The nature and occurrence of gallstones in Taiwan and their etiologic factors might not be the same as in Western countries and warranted a systematic investigation. Gallbladder biles and gallstones were obtained at surgery from 100 and 74 patients, respectively. Common duct bile and stones were either drained through an indwelling common duct T-tube or aspirated through a nasobiliary catheter in 108 patients. Gallstones were analyzed for bilirubin, cholesterol, bile acid, calcium, and residue, and biles for bile acid, cholesterol, phospholipid, bilirubin, and beta-glucuronidase. There were four major kinds of gallstones in Taiwan: cholesterol/mixed stones, high-residue black formed pigment stones, low-residue brown formed pigment stones, and muddy pigment stones. The surgical incidence of all types of stones increased steadily during the past four decades. During the past 15 years the relative frequencies for mixed, formed pigment, and muddy pigment stones had been roughly 40, 40, and 20%, respectively, with a further increase in the mixed stones and a decrease in the muddy pigment stones in recent years. Improvement of nutritional status and living standards might contribute to such changes. Cholesterol content in the common duct and gallbladder biles was higher in the mixed stone group than in other groups. Bacterial beta-glucuronidase activity was detected in 53% of patients with muddy pigment stones. Endogenous beta-glucuronidase activity and concentration were also highest in this group, intermediate in the formed pigment and mixed stone group, and lowest in the control. We concluded that hypercholesterobilia was responsible for increasing incidence of mixed stones during the past two decades, while both bacterial and human beta-glucuronidase might contribute to pigment cholelithiasis.     

Which operations can be done without general anesthesia?

The fatty acid composition of erythrocytes, platelets, and serum lipids was compared between subjects who had been eating a strict uncooked vegan diet ("living food") for years and omnivore controls. The vegan diet contains equal amounts of fat but more monounsaturated and polyunsaturated and less saturated fatty acids than the mixed diet of the control group. In vegans, the proportion of linoleic acid was greater in all lipid fractions studied. Also, the levels of other n-6 fatty acids were greater, with the exception of arachidonic acid levels, which were similar in most fractions. In erythrocytes, platelets and serum phospholipid fractions, this increase was mainly at the expense of the n-3 fatty acids. The proportions of eicosapentaenoic and docosahexaenoic acid were only 29-36% and 49-52% of those in controls, respectively. In vegans the ratio of n-3 to n-6 fatty acids was only about half that in omnivores. In addition to the lower levels of n-3 fatty acids, the proportions of palmitic and stearic acids were lower in serum cholesteryl esters, triglycerides and free fatty acids of vegans. The proportion of oleic acid was slightly lower only in serum cholesteryl esters and erythrocyte phosphatidylserine. The results show that, in the long term, the vegan diet has little effect on the proportions of oleic and arachidonic acids, whereas the levels of n-3 fatty acids are depressed to very low levels with prolonged consumption of the high linoleic and oleic acid components of this diet.     

Distinct effects of fatty acids on translocation of gamma- and epsilon-subspecies of protein kinase C

Effects of fatty acids on translocation of the gamma- and epsilon-subspecies of protein kinase C (PKC) in living cells were investigated using their proteins fused with green fluorescent protein (GFP). gamma-PKC-GFP and epsilon-PKC-GFP predominated in the cytoplasm, but only a small amount of gamma-PKC-GFP was found in the nucleus. Except at a high concentration of linoleic acid, all the fatty acids examined induced the translocation of gamma-PKC-GFP from the cytoplasm to the plasma membrane within 30 s with a return to the cytoplasm in 3 min, but they had no effect on gamma-PKC-GFP in the nucleus. Arachidonic and linoleic acids induced slow translocation of epsilon-PKC-GFP from the cytoplasm to the perinuclear region, whereas the other fatty acids (except for palmitic acid) induced rapid translocation to the plasma membrane. The target site of the slower translocation of epsilon-PKC-GFP by arachidonic acid was identified as the Golgi network. The critical concentration of fatty acid that induced translocation varied among the 11 fatty acids tested. In general, a higher concentration was required to induce the translocation of epsilon-PKC-GFP than that of gamma-PKC-GFP, the exceptions being tridecanoic acid, linoleic acid, and arachidonic acid. Furthermore, arachidonic acid and the diacylglycerol analogue (DiC8) had synergistic effects on the translocation of gamma-PKC-GFP. Simultaneous application of arachidonic acid (25 MicroM) and DiC8 (10 microM) elicited a slow, irreversible translocation of gamma-PKC- GFP from the cytoplasm to the plasma membrane after rapid, reversible translocation, but a single application of arachidonic acid or DiC8 at the same concentration induced no translocation. These findings confirm the involvement of fatty acids in the translocation of gamma- and epsilon-PKC, and they also indicate that each subspecies has a specific targeting mechanism that depends on the extracellular signals and that a combination of intracellular activators alters the target site of PKCs.     

Essential fatty acids in the serum and cerebrospinal fluid of multiple sclerosis patients

Statistical evaluation of essential fatty acids (determined by gas chromatography) in the serum and cerebrospinal fluid of patients with definite MS and acute CCT showed marked differences as compared to healthy subjects. It was also evident that the decrease of essential fatty acids in MS patients differed from that of CCT patients. Whereas the fatty acid levels in the serum of MS patients revealed only minor differences as compared to the controls and CCT patients, MS patients did show a clear decrease, especially of linoleic and arachidonic acids, in the CSF. This difference was most pronounced in cholesterol esters in the CSF. One absorption study with safflower oil demonstrated normal enteral absorption of essential fatty acids and the ability to cross the blood-CSF barrier.     

Effect on the partition equilibrium of various drugs by the formation of mixed bile salt/phosphatidylcholine/fatty acid micelles. A characterization by micellar affinity capillary electrophoresis. Part IV

Mixed micelles, which mimic the bile containing fatty acids in the gastrointestinal tract, were used as a pseudostationary phase in capillary electrophoresis. The mixed micellar system studied contained the dihydroxy bile salts sodium glycodeoxycholate or sodium taurodeoxycholate or the trihydroxy bile salt sodium taurocholate, in association with different sodium salts of fatty acids including lauric, myristic, palmitic, oleic, stearic and linoleic acid and lecithin or dipalmitoylphosphatidylcholine as phospholipid. The determination of the changing mobilities of ionic analytes in the presence of mixed micelles reflected interactions between the used drugs and the mixed micelles. These were determined as dependence on the fatty acid concentration in the bile salt/fatty acid micelles and the mixed bile salt/phosphatidylcholine/fatty acid micelles. The capacity factor kappa MMC, for the partition between mixed micellar and aqueous phase was calculated. The partition equilibrium of basic and acidic drugs depends considerably on shape and charge of the mixed micelles (dependent on the fatty acid concentration) as well as on the acid-base properties of the drug. The mobility of the micelle aggregates was determined as an important reference value to the calculations of kappa MMC. This paper also describes the use of laser-induced fluorescence detection and electrospray mass spectrometry and tandem mass spectrometry for the characterization of the mixed micelle composition.     

Influence of membrane heterogeneity on kinetics of nonelectrolyte tracer flows

The importance of various unsaturated fatty acid triglycerides to the repair of faulty skin barrier function was studied in essential fatty acid-deficient rats. Following cutaneous application of the pure triglycerides for up to 5 days, the hitherto high rate of transepidermal water loss, characteristic of essential fatty acid deficiency in rats, was reduced by the triglycerides of linoleic and gamma-linolenic acids. Incorporation of the applied fatty acids into the lecithin of the epidermis accompanied these changes in water loss, indicating that cutaneously applied triglycerides may be metabolized by the skin and incorporated into complex lipids. Other fatty acid triglycerides, including alpha-linolenic, dihomo-gamma-linolenic, arachidonic and omega-7-heneicosatrienoic acid, did not lower the rate of transepidermal water loss, although all were incorporated into epidermal structural lipids. The non-essential oleic acid also had no effect upon the rate of transepidermal water loss. These data suggest that of the two main essential fatty acids that occur in skin, linoleic acid and arachidonic acid, the former specifically plays an important role in regulating barrier function whereas the later may have a separate function, such as serving as a precursor of prostaglandins.     

Elaboration of the messenger transport organizer pathway for localization of RNA to the vegetal cortex of Xenopus oocytes

1. Two experiments were designed to study the influence of free fatty acid content and degree of saturation of free fatty acids and neutral fat on digestibility of added fats and fatty acids. Sunflower oil and tallow were used as neutral fats, and palmitic, stearic, oleic and linoleic acids as free fatty acids. Fat inclusion was 80 g/kg and mixtures of each fat and each free fatty acid were prepared in the proportions 100:0, 70:30 and 40:60. 2. Experimental diets were evaluated for fat and fatty acid digestibilities with broiler chickens at 21 d of age. The metabolisable energy of fat was calculated from the product of digestibility and gross energy. Increasing concentrations of saturated free fatty acids decreased the ME of added fat, whereas unsaturated free fatty acids did not significantly affect the ME value of added fat. 3. Digestibilities of individual fatty acids were analysed by linear regression with rate of inclusion of free fatty acid in the fat blend: palmitic and stearic acids gave a negative slope, whereas oleic and linoleic acids gave a slope not statistically different from zero. Because slopes for saturated fatty acids did not differ between the sunflower oil and tallow treatments, synergism between unsaturated and saturated fatty acids was not detected.     

Behavior of various cholesterol crystals in bile from patients with gallstones

Besides classical plate-like cholesterol monohydrate crystals, a variety of crystal shapes have recently been described in model biles but their relevance for human gallstone formation is unknown. We therefore studied crystallization behavior in gallbladder bile from cholesterol stone patients (54 untreated, 13 ursodeoxycholate-treated) and 6 pigment stone patients. Bile preparation by ultrafiltration or ultracentrifugation left biliary lipid composition unchanged but plates and their aggregates, and arcs and needles crystallized more extensively while spirals and tubules crystallized less extensively in ultra-centrifuged bile than in ultrafiltered bile. Plates, aggregates, and arcs/needles were seen in 90 percent, 36 percent, and 18 percent of the cases respectively of fresh unfiltered biles of untreated cholesterol stone patients, while spirals and tubules were always absent. In ultrafiltered biles arcs/needles, plates and aggregates progressively developed as persistent forms. Spirals and tubules occurred transiently and were associated with increased deoxycholic acid (+41 percent, P = .039) and with more extensive cholesterol crystallization. Rate/extent of crystallization of all crystal forms was higher (P < .0001) for multiple than solitary cholesterol stone patients. Ursodeoxycholate-treated patients had atypical platelike cholesterol crystals in fresh unfiltered biles that decreased in size at prolonged observation and in 2 cases even dissolved after 15 and 20 days. No crystals ever developed in ultra-filtered bile of ursodeoxycholic acid (UDCA)-treated patients during 21 days. Pigment stone patients seldom developed crystals. Thus, plates, aggregates and arcs/needles are persistent forms with high crystallization rate in multiple cholesterol stone patients. Tubules and spirals are transient forms that are associated with more extensive crystallization. Patients treated with ursodeoxycholate often have atypical crystals in their fresh bile.     

Dietary stearic acid reduces plasma and hepatic cholesterol concentrations without increasing bile acid excretion in cholesterol-fed hamsters

Although there is general agreement that saturated fatty acids elevate plasma cholesterol concentrations, the relative effects of individual fatty acids on cholesterol and bile acid metabolism are less clear. In this study, cholesterol and bile acid responses to diets enriched in different saturated fatty acids were investigated in hamsters. The six diets examined were as follows: 5% fat (g/100 g) enriched in palmitic acid (16:0) with no cholesterol, 5% fat 16:0-enriched, 0.05% cholesterol (wt/wt), and four diets containing 0.05% cholesterol and 15% fat with each diet enriched in lauric (12:0), myristic (14:0), palmitic (16:0), or stearic acid (18:0). Total plasma cholesterol concentration was significantly greater in hamsters fed the 14:0-enriched diet relative to those fed the 18:0-enriched diet (P < 0.05). Both plasma and liver cholesterol concentrations of hamsters fed 18:0 did not differ from those of the group fed no dietary cholesterol. In all instances, differences in total plasma cholesterol were accounted for within the HDL fraction; no significant treatment differences in VLDL or LDL cholesterol were found. Total daily fecal bile acid excretion was higher in hamsters fed the 15% fat 16:0 diet compared with those fed no dietary cholesterol (P < 0.05), but not significantly different from other treatment groups. There was greater deoxycholic acid excretion (P < 0.05) from hamsters fed the 14:0 and 16:0 diets compared with those fed the 18:0-enriched diet. Small intestinal + gallbladder bile acids, an index of pool size, did not differ significantly among the groups. The observed relative hypocholesterolemic effect of stearic acid was not mediated by increased bile acid excretion.     

Clear cell sarcoma of soft tissues. Clinico-pathological and ultrastructural analysis of a case in the head-neck region and a literature review]

BACKGROUND: A high concentration of arachidonic acid in maternal erythrocytes and trophoblast could have a role in pre term deliveries. AIM: To study the fatty acid composition of long chain fatty acids from erythrocytes of mothers who gave birth to pre term and full term infants. PATIENTS AND METHODS: Thirty three healthy women that gave birth to healthy newborns in a public hospital were studied. Twenty two had pre term (34 weeks) and 11 full term (40 weeks) deliveries. The fatty acid profile of phospholipids isolated from erythrocytes of these women was analyzed by gas-liquid chromatography. RESULTS: Compared to women giving birth to full term infants, phospholipids of women giving birth to pre term infants had a higher content of arachidonic acid (20:4 omega 6) and all the species of omega 6 fatty acids. They also had a lower concentration of palmitic and eicosapentanoic (20: 5 omega 3) acids and thus a higher arachidonic acid/eicosapentanoic acid ratio. CONCLUSIONS: A high arachidonic acid content in phospholipids of erythrocytes could be a risk factor or predictive marker for pre term deliveries.     

Composition of biliary lipids and kinetics of bile acids after cholecystectomy in man

Postcholecystectomy biliary lipid composition and bile acid kinetics were studied in 24 women and 4 men. Hepatic bile was collected periodically for as long as 4 months without interrupting the enterohepatic circulation and without infecting the biliary system. In 23 patients with cholesterol gallstones, fasting biliary cholesterol made up 10.2% of total lipids in the steady state; in 5 patients with bilirubinate stones, saturation of fasting hepatic bile with cholesterol was lower (8.7% of total lipids). The percentage of deoxycholic acid after cholecystectomy was not higher than that of seven healthy, noncholecystectomized controls. Postcholecystectomy studies of diurnal variation of biliary lipids (7 patients) showed that postprandial hepatic bile had a significantly lower cholesterol saturation than fasting bile. Pool sizes of cholic and chenodeoxycholic acids were low (average 0.4 g/70 kg, each); total synthesis for both bile acids was normal (average 460 mg/day/70 kg), but fractional turnover rates of the two primary bile acids increased after cholecystectomy, probably due to more frequent recycling of the small bile acid pool.     

Fatty acids of vegetative cells and spores of Bacillus licheniformis

Lipids were extracted from vegetative cells and spores of Bacillus licheniformis. Vegetative cells were grown in nutrient broth and spores on nutrient agar. Total lipid approximated 2.89% of the dry weight of vegetative cells and 2.09% of the dry weight of spores. The fatty acids were prepared as methyl esters and analyzed by gas chromatography and mass spectrometry. There were six fatty acids in concentrations greater than 5% of the total lipid in both spores and vegetative cells, but only palmitic acid was common to both. Fatty acids from vegetative cells in quantities of 5% or more of the total lipid material were lauric, myristic, palmitic, palmitoleic, and linoleic acids. Fatty acids from spores in concentrations greater than 5% of the total lipid were isopentadecylic, palmitic, Carbon-17 iso, and three other long or branched chain fatty acids which were not identified. Spores contained more long and branched chain fatty acids with odd numbers of carbon atoms than did vegetative cells.     

Binocular processes in vernier acuity

The contribution of synthesis and dietary sequestration to the high arachidonate content of the lone star tick, Amblyomma americanum, salivary glands was investigated by assessing the salivary metabolites of various radiolabeled fatty acid substrates administered to partially fed females. A portion of each of the fatty acids studied was incorporated into the fatty acid moiety of the phospholipid fraction. [14C]acetate was metabolized only into myristic, palmitic, palmitoleic, steric, and oleic acids. [3H]oleic acid, [14C]linoleic acid, [14C]gamma-linolenic acid and [14C]eicosatrienoic acids were incorporated into salivary gland phospholipids but underwent little change including elongation and/or desaturation to arachidonate. Ingested [3H]arachidonic acid was readily taken up by the salivary gland and distributed among the lipid classes in a pattern markedly different from that of the other fatty acids tested. We conclude that ticks are unable to synthesize arachidonic acid for incorporation into the salivary glands, but rather sequester it from the host bloodmeal.     

Effect of deoxycholate on immunoglobulin G concentration in bile: studies in humans and pigs

Because an increase in biliary deoxycholate levels seems to be a risk factor for cholesterol gallstone formation, we determined the relationship between deoxycholate levels and levels of the pronucleating protein, immunoglobulin G (Ig) in human gallbladder bile. Patients with cholesterol gallstones had a higher concentration of biliary IgG compared with a pigmented stone group and control patients. This was associated with the simultaneous presence of two conditions in the cholesterol stone group, supersaturated bile and a high deoxycholate/cholate ratio. The other patient groups met only one of the two conditions. Next, animal studies were performed to determine if model biles mimicking the two conditions could affect IgG secretion by the gallbladder. Gallbladders were exposed in vivo and then in an Ussing chamber to model biles. The voltage clamp technique was used to monitor functional integrity of the preparation. Three different model biles were tested: (1) taurodeoxycholate (TDC), 80%; taurocholate (TC), 20%; and cholesterol saturation index (CSI), 1.2; (2) TDC, 20%; TC, 80%; and CSI, 1.2; and (3) TDC, 80%; TC, 20%; and CSI, 0.6. IgG concentrations became significantly higher in group 1 than in the other two groups. The concentration of mucous glycoprotein was also significantly greater in group 1 when compared with group 2. Plasma cells were increased in number in mucosal and submucosal layers in group 1. We conclude that cholesterol supersaturated model bile with high content of TDC induces gallbladder epithelial alterations, which increase the luminal concentration of IgG and mucous glycoprotein.     

Repeated bile acid therapy for the long-term management of cholesterol gallstones

BACKGROUND/AIMS: Following non-surgical treatment, cholesterol gallstones recur in a high proportion of patients, and recurrence cannot be predicted nor effectively prevented. Our aim was to test prospectively the viability and the efficacy of repeated bile acid therapy, in which recurrent stones are diagnosed at an early stage by regular ultrasound monitoring and promptly retreated, as a strategy for the management of these patients in clinical practice. METHODS: One hundred and seventy-two consecutive patients were recruited upon achieving complete gallstone dissolution using non-surgical therapy (bile acids or lithotripsy plus bile acids), and followed up at 6-monthly intervals by ultrasound scan. Gallstone recurrence was promptly treated by a combination of ursodeoxycholic acid plus chenodeoxycholic acid (5 mg/kg per day each) for a period of 2 years, or less if complete redissolution was achieved. Median follow-up period was 34 months (range 6-70). RESULTS: Forty-five patients had gallstone recurrence; of these, 39 underwent one or more repeated courses of bile acid therapy (follow-up data available in 27). Gallstone recurrence rate was 15% at 1 year and 47% at 5 years. Average annual redissolution rate of recurrent gallstones (intention to treat) was 41%. The proportion of gallstone-free patients in the whole population was 88%, 84%, 77%, 78%, 75% at 1-5 years, respectively, and rose to > 90% at 3 years onwards in patients with single primary stones. CONCLUSIONS: We conclude that repeated bile acid therapy maintains the majority of patients gallstone free, and is therefore an effective long-term management strategy, especially in patients with primary single gallstones.     

Fractal analysis of photolysis of nitrosyl haemoglobin at low temperatures

In Mycobacterium phlei, fatty acid unsaturation increased with decreasing temperature. The 10-hexadecenoic acid content increased as the temperature was reduced from 35 degrees C to 26-20 degrees C. At lower temperatures tuberculostearic acid decreased while oleic and linoleic acids increased, the latter being found in M. phlei for the first time. Concomitantly palmitic acid content decreased, and the 6- and 9-hexadecenoic acids increased slightly on reducing the temperature from 35 to 10 degrees C. Thus, down to 26-20 degrees C palmitic acid was mainly replaced by 10-hexadecenoic acid. From this range down to 10 degrees C, palmitic and tuberculostearic acids were replaced by oleic and linoleic acids. Consequently, fatty acid branching decreased and mean chain length increased, as the temperature was reduced. These observations support the view that regulation of membrane fatty acid composition is part of microbial temperature adaptation, and that the mechanism behind the responses might be more complex than generally believed.