Three-dimensional rendering of otolith growth using phase contrast synchrotron tomography.

A three-dimensional computer reconstruction of a plaice Pleuronectes platessa otolith is presented from data acquired by the Diamond Light synchrotron, beamline I12, X-ray source, a high energy (53-150 keV) source particularly well suited to the study of dense objects. The data allowed non-destructive rendering of otolith structure, and for the first time allows otolith annuli (internal ring structures) to be analysed in X-ray tomographic images.

Visualising fat reserves in an insect: A method using X-ray micro-computerised tomography of the Common Wasp (Vespula vulgaris).

The Common Wasp, Vespula vulgaris (Hymenoptera: Vespidae), has an annual nest cycle with new colonies initiated by over-wintered queens. Survival of adult queen wasps through winter dormancy is enabled through the deposition of substantial quantities of triglycerides in fat bodies. Worker (and male) wasps lack these fat reserves. By comparing micro-CT scans of workers, pre-hibernation queens and post-hibernation queens, we demonstrate that it is possible to semi-quantitatively measure fat reserves using arbitrary X-ray attenuation ranges. Venom in the venom gland of the queen wasps, has a significantly lower X-ray attenuation value than the triglyceride-rich fat bodies. This may be due to its content of low molecular weight volatile pheromones in addition to its other known constituents. We also demonstrate the utility of micro-CT for visualising a range of physiological and anatomical features of insects. This non-destructive method for measuring fat reserves can be used on appropriately preserved or freshly collected insect specimens.

The tracheal system of the Common Wasp (Vespula vulgaris) - A micro-CT study.

X-ray micro-CT has been used to study the tracheal system of Pre and Post hibernation Queen wasps (Vespula vulgaris) and their workers. We have compared our findings in wasps with Snodgrass's description of the tracheal system of the honeybee as characterised by anatomical dissection. Our images, whilst broadly similar, identify the tracheal system as being considerably more complex than previously suggested. One of the 30 wasps imaged had a markedly different, previously undescribed tracheal system. Since completing this study, a large micro-CT study from the American Museum of Natural History (AMNH) has been published. This used different software (Slicer) and analysed 16bit digital data. We have compared our methods with that described in the AMNH publication, adopted their suggested nomenclature and have made recommendations for future studies.

Cholesterol-lowering effect of mevinolin, an inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme a reductase, in healthy volunteers.

Mevinolin reduces cholesterol synthesis by inhibiting 3-hydroxy-3-methylglutaryl-coenzyme A reductase. The safety and effectiveness of this agent was evaluated in a double-blind, placebo-controlled study in 59 healthy men (serum cholesterol 3.88--7.76 mmol/liter) in five centers. Subjects maintained their usual diet and activities. Doses of 6.25, 12.5, 25, or 50 mg twice daily for 4 wk produced mean reductions of total serum cholesterol fo 23--27% [vs. placebo (4%), P less than 0.01]. Mean low density lipoprotein cholesterol fell 35--45%, while high density lipoprotein and very low density lipoprotein cholesterol, and triglycerides were not significantly affected. Mean apolipoprotein B fell 27--34%. 50 mg was not significantly more effective than 6.25 mg. Mevinolin was generally well tolerated, and no serious clinical or laboratory abnormalities occurred. One subject (12.5 mg) was withdrawn because of abdominal pain and diarrhea. These results suggest that if long-term safety can be demonstrated, inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase are likely to prove useful in the treatment of hypercholesterolemia.

Long-term study of re-infection following successful eradication of Helicobacter pylori infection.

BACKGROUND: 'Re-infection' with Helicobacter pylori after eradication has been estimated to occur in 0-14% of patients, although most so-called 're-infections' occur within the first year following 'eradication' and many may actually be due to recrudescence of a temporarily suppressed infection. AIM: To study the true re-infection rate, we have studied re-infection rates after eradication therapy by excluding the first year's data, minimizing the possible confounding effect of recrudescence. METHODS: All patients tested for H. pylori infection following eradication therapy between 1987 and 2004 were evaluated. Testing was carried out by urea breath test and gastric biopsy. Patients were included if they were found to be negative for H. pylori infection by testing at least 1 year following eradication and underwent at least one further test for H. pylori. RESULTS: 1162 patients met the inclusion criteria with median post-eradication follow-up of 3 years (1.5-14) including 4668 tests; 3319 years of follow-up were analysed. Thirteen cases of re-infection occurred (re-infection rate 0.4% per year). CONCLUSIONS: This large study of H. pylori re-infection avoided cases of recrudescence by excluding the first post-eradication year. True re-infection is probably less common than previously thought.

Dietary cyclandelate decreases pre-established atherosclerosis in the rabbit.

Rabbits were given a diet containing 1% (w/w) cholesterol for 7 weeks to initiate atherosclerosis and then transferred to a low-cholesterol diet (regression diet) with or without 0.5% (w/w) cyclandelate for 10 weeks. In those fed regression diet alone aortic atherosclerosis increased significantly. Cyclandelate treatment decreased the extent and severity of aortic atherosclerosis. Thus in rabbits receiving cyclandelate the total cholesterol and calcium content of aorta was decreased by 45% and 69% of control values, respectively. The effects of cyclandelate occurred without significant lowering of serum cholesterol or alteration of cholesterol content of liver or calcium content of serum, liver or muscle. The result suggests a specific action of cyclandelate on atheromatous accumulations of the aortic wall.

Elevation of serum high density lipoprotein cholesterol by rowachol, a proprietary mixture of six pure monoterpenes.

Rowachol, a proprietary choleretic containing 6 pure monoterpenes markedly elevates serum HDL cholesterol (SHDL-C) concentrations in man. The concentration of SHDL-C showed a progressive increase in 16 patients treated with 6-9 capsules of Rowachol daily for periods of 2-28 weeks. There was no accompanying significant change in the concentrations of serum total cholesterol or triglyceride. In view of the significant inverse relationship between SHDL-C concentration and the risk of developing ischaemic heart disease, it is suggested that Rowachol and possibly other terpenes merit further investigation as possible therapeutic agents in the prevention and treatment of atheroma.

The effects of 3,5,5-trimethylcyclohexanol on hepatic cholesterol synthesis, bile flow and biliary lipid secretion in the rat.

The chemical trimethylcyclohexanol (TMC) is closely related to menthol, the major component of a terpene preparation with known choleretic and cholelitholytic activity. Its effects on hepatic cholesterol synthesis and bile secretion were examined in the rat. In both acute and long-term dosing experiments TMC significantly inhibited hepatic S-3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase. TMC was a potent choleretic, with detectable effects on bile flow at low doses, which also reduced coupling of cholesterol secretion to bile salt secretion. Single large doses tended to lower biliary cholesterol output and caused significant reduction in cholesterol saturation index after biliary diversion for 1 h. TMC and its widely prescribed ester cyclandelate, which is rapidly degraded to TMC after ingestion, should be investigated further as potential cholelitholytic treatments in man.

In vivo inhibition of hepatic lipogenesis in the rat by cyclandelate (3,3',5-trimethylcyclohexanylmandelate).

Rates of hepatic lipogenesis were measured in vivo in rats by incorporation into lipids of [3H] from injected [3H]H2O 17 hr after a single oral dose of cyclandelate (3,3',5-trimethylcyclohexanylmandelate, a vasoactive substance). Cyclandelate administration resulted in a significant inhibition (40-60%) of both sterol and fatty acid synthesis in the livers which was independent of the 3.2-fold diurnal variation in the rates of hepatic sterol and fatty acid synthesis. The inhibition of accumulation of newly synthesized fatty acid in intestine also reached statistical significance. The accumulation of newly synthesized sterol was significantly depressed in serum but did not result in any change in the concentration of serum total cholesterol. These results are interpreted in terms of the inhibitory effect of cyclandelate on hepatic 3-hydroxy-3-methylglutaryl-CoA reductase previously reported by us (Biochem. Pharmac. 32, 649, 1983).

The inhibition of the oxidation of low density lipoprotein by (+)-catechin, a naturally occurring flavonoid.

(+)-Catechin inhibited the copper-catalysed oxidation of human low density lipoprotein (LDL) in a dose-dependent manner with complete inhibition at 20 micrograms/mL. The flavonoid at a concentration of 50 micrograms/mL also inhibited oxidation of LDL induced by the mouse transformed macrophage J774, human monocyte-derived macrophages and vascular endothelial cells isolated from human umbilical cords. LDL modified by copper-catalysed or cell-induced oxidation was endocytosed and degraded by human macrophages at a much greater rate than native LDL. LDL reisolated from copper or cell incubations in the presence of (+)-catechin was endocytosed and degraded at rates similar to native LDL. (+)-Catechin appeared to inhibit the uptake and degradation by macrophages of cell-modified LDL. The actions of (+)-catechin on cell-induced oxidation of LDL are consistent with the ability of flavonoids of similar structure to inhibit lipoxygenases and with a role for lipoxygenases in cell-induced modification of LDL in vivo.

The inhibition of hepatic S-3-hydroxy-3-methylglutaryl-CoA reductase by 3,3,5-trimethylcyclohexanol and its mandelic acid ester, cyclandelate.

Rat hepatic HMGCoA reductase was found to be at least 50% inhibited 17 hr after administration of a single oral dose of 3,3,5-trimethylcyclohexanyl mandelate (cyclandelate), a vasoactive substance. This inhibition was also found in rats given the 3,3,5-trimethylcyclohexanol component but only slight inhibition was seen after an equimolar dose of mandelate. The inhibition of HMGCoA was observed both around the high point and near the low point of the diurnal activity cycle. The effect did not persist to 41 hr after treatment. There was no direct inhibition of HMGCoA reductase by trimethylcyclohexanol when added to the assay system in vitro. The in vivo effect of these inhibitors was specific for HMGCoA reductase. There was no change, neither elevation nor depression, of the amount of microsomal membrane components cytochromes b5 and P-450, not was the activity of another microsomal enzyme, arylesterase, affected by dosing with cyclandelate or trimethylcyclohexanol.

Conference report: duodenal ulcer trials reported at the European Helicobacter pylori Study Group, Edinburgh 1995.

The abstracts from the 8th International Workshop on Gastro-duodenal Pathology and Helicobacter pylori held in Edinburgh, 7-9 July 1995, are published in Gut 1995; 37 (Suppl. 7). I was privileged to act as reporter to the Plenary Workshop on Duodenal Ulcer Trials chaired by Prof. Seppala. Prof. Roy Pounder and I felt that in such a fast moving field as Helicobacter pylori there would be some merit in briefly reviewing the eight excellent papers presented at the Workshop. The main reason for this being that six of the presentations were well conducted randomized prospective clinical trials of H. pylori eradication therapy and the other two had important clinical messages.

Review article: premedication and intravenous sedation for upper gastrointestinal endoscopy.

Upper gastrointestinal endoscopy can be performed without intravenous sedation but the evidence suggests that, in the United Kingdom and United States, most patients and endoscopists prefer that some form of premedication is given. Intravenous diazepam or midazolam are used by the majority of endoscopists. In the UK, the ratio of diazepam to midazolam users is approximately 2:1, while in the USA more endoscopists are now using midazolam. Midazolam is approximately twice as potent as diazepam but, when allowance is made for this, there is probably little or no difference in the propensity of the two drugs to produce respiratory depression. The antegrade amnesic effect of midazolam is significantly superior to that of diazepam. A benzodiazepine/narcotic combination can achieve a smoother and more rapid induction with less gagging and choking, but the incidence of adverse outcomes--particularly respiratory depression--is increased significantly. Over 50% of the deaths that are associated with upper gastrointestinal endoscopy are due to cardiopulmonary problems. Hypoxia is very common if measured using non-invasive monitoring equipment, such as a pulse oximeter. Methods of preventing oxygen desaturation and thus, by inference, most cardiac arrhythmias associated with endoscopy are discussed, as is the role of flumazenil, the new benzodiazepine antagonist.

Pattern of breathing during upper gastrointestinal endoscopy: implications for administration of supplemental oxygen.

Cardiopulmonary complications account for half the deaths associated with upper gastrointestinal endoscopy. The incidence of hypoxia at the time of upper gastrointestinal endoscopy can be greatly reduced by the administration of supplemental oxygen via nasal cannulae. Using dual thermistors in the mouth and nostrils of patients undergoing upper gastrointestinal endoscopy, the present study demonstrates that most patients breathe predominantly via the oral, rather than the nasal, route following intubation of the oesophagus. The implication from the study is that, if supplemental oxygen is to be used in 'at risk' patients, it would be logical to employ an oral, rather than nasal, route of administration.

Bolus or slow titrated injection of midazolam prior to upper gastrointestinal endoscopy? Relative effect on oxygen saturation and prophylactic value of supplemental oxygen.

A total of 131 patients undergoing upper gastrointestinal endoscopy were sedated with midazolam given as a bolus injection over 5 seconds. The oxygen saturation was continuously measured using a pulse oximeter. Supplemental oxygen was given via nasal cannulae at a rate of 3 litres per minute to 54 patients, while the remaining 77 patients only received oxygen if their oxygen saturation dropped below 85%. Both groups in the present series were compared with 3 previously published series of patients, in whom we had used intravenous midazolam as a slow titrated injection. Despite using on average only two-thirds of the dose of midazolam, following bolus injection the degree of oxygen desaturation during the endoscopic procedure was greater, and the ability of supplemental oxygen delivered via nasal cannulae to prevent hypoxia was less (P less than 0.01), than with a slow titrated injection.

Rapid eradication of Helicobacter pylori infection.

BACKGROUND/AIMS: Current Helicobacter pylori eradication therapy for peptic ulcer disease usually involves a 2-week course of either a bismuth preparation or omeprazole in combination with antibiotics. We have studied a shorter, 7-day course of treatment to assess efficacy and tolerability. METHODS: Four hundred and thirty-six patients, in three non-randomized groups, received omeprazole (40 mg mane), amoxycillin (500 mg t.d.s.) and metronidazole (400 mg t.d.s.): 308 patients received the triple combination for 14 days; 80 patients were treated for 7 days; and 48 patients received omeprazole and amoxycillin for 7 days but metronidazole for only 5 days. RESULTS: Helicobacter pylori was eradicated in 89.5%, 91.1% and 87.5%, respectively (98.3%, 92.9% and 100% of metronidazole-sensitive isolates and 75.6% and 88.2% of metronidazole-resistant isolates in the first two groups). Side effects were significantly more frequent in patients who received 14 days (49%) compared with 7 days of treatment (33%); only 8/308 and 1/128 patients, respectively, failed to complete the course. CONCLUSIONS: On the basis of efficacy, tolerability and cost, we conclude that a 7-day course of the omeprazole (40 mg mane), amoxycillin (500 mg t.d.s.) plus metronidazole (400 mg t.d.s.) combination is effective therapy for the eradication of H. pylori.

Omeprazole and Helicobacter pylori: temporary suppression rather than true eradication.

Twenty-four Helicobacter pylori (H. pylori)-positive patients were treated for 28 days with either 20 mg omeprazole o.m. (n = 12) or 40 mg omeprazole o.m. (n = 12). Clearance (absence of H. pylori at the end of or shortly after treatment) and eradication (absence of H. pylori 1 month after cessation of treatment) were assessed using the 14C-urea breath test. Observed clearance and eradication were: 20 mg omeprazole 3/12 and 0/12; 40 mg omeprazole 6/12 and 1/12 respectively. The effect on H. pylori is probably due to the change in gastric pH from acid to neutral, however it is insufficient to recommend the inclusion of omeprazole in regimens aimed at eradicating H. pylori.

Short report: omeprazole plus antibiotic combinations for the eradication of metronidazole-resistant Helicobacter pylori.

Twenty-eight Helicobacter pylori-positive patients with metronidazole-resistant isolates and 25 with metronidazole-sensitive isolates were treated for 14 days with 40 mg omeprazole nocte plus 500 mg amoxycillin t.d.s. Eradication of H. pylori, defined as absence of the organism one month after cessation of treatment, was assessed using the [14C]urea breath test. The eradication rate in patients with metronidazole-resistant isolates was 14/28 (50%) while that in patients was metronidazole-sensitive isolates was 12/25 (48%). In contrast to these encouraging eradication rates, very poor results were obtained with a 7-day course of omeprazole (40 mg nocte) in combination with erythromycin ethylsuccinate (500 mg q.d.s.) and tripotassium dicitrato bismuthate tablets (120 mg q.d.s.). The latter eradication rates were 3/20 (15%) in patients taking erythromycin tablets and 3/19 (16%) in those taking a liquid formulation of erythromycin. All treatment regimens were well tolerated and all patients completed the prescribed course of therapy.

Does a previous course of tripotassium dicitrato bismuthate affect the subsequent chances of successful Helicobacter pylori eradication?

We have performed a retrospective study of 103 patients with either peptic ulcer or non-ulcer dyspepsia, infected with metronidazole-sensitive strains of Helicobacter pylori (H. pylori), who were treated with a combination of tripotassium dicitrato bismuthate and metronidazole for a period of at least two weeks. Dual therapy with tripotassium dicitrato bismuthate plus metronidazole showed similarly high eradication rates (greater than or equal to 80%) of H. pylori from patients irrespective of age, gender or clinical diagnosis. Most importantly, dual therapy achieved a similar eradication rate of H. pylori infection in 41 patients who had previously been treated with tripotassium dicitrato bismuthate alone or in combination with an antibiotic other than metronidazole. It therefore appears that H. pylori does not become resistant to treatment with tripotassium dicitrato bismuthate.

Experience with 'triple' anti-Helicobacter pylori eradication therapy: side effects and the importance of testing the pre-treatment bacterial isolate for metronidazole resistance.

At the 1990 World Congresses of Gastroenterology, the Working Party on Helicobacter pylori (H. pylori) recommended that, in suitable patients, the bacterium should be eradicated using a therapeutic regimen comprising a bismuth salt, tetracycline and metronidazole for two weeks. We have treated 40 patients infected with H. pylori with 'triple' therapy consisting of 120 mg tripotassium dicitrato bismuthate q.d.s., 500 mg tetracycline q.d.s. and 400 mg metronidazole t.d.s. for two weeks. The success rate, in terms of bacterial eradication, was 19/21 (90.5%) in patients with metronidazole-sensitive organisms, compared with only 6/19 (31.6%) in patients whose H. pylori were resistant to metronidazole (P less than 0.01). Side effects, particularly diarrhoea and vomiting/nausea, were common: 23/40 patients reported such symptoms during the 14-day course of therapy. Fifteen of these 23 patients completed the entire 14-day course, although suffering from significant side effects, while the remaining eight patients had to discontinue the treatment because side effects became intolerable. If a form of triple therapy is going to be widely used to eradicate H. pylori infection, the regimen will have to be simpler, shorter, produce fewer side effects and be more effective in patients with metronidazole-resistant bacteria.