Characterizing osmolyte chemical class hierarchies and functional group requirements for thermal stabilization of proteins.

Osmolytes are naturally occurring organic compounds that protect cellular proteins and other macromolecules against various forms of stress including temperature extremes. While biological studies have correlated the accumulation of certain classes of osmolytes with specific forms of stress, including thermal stress, it remains unclear whether or not these observations reflect an intrinsic chemical class hierarchy amongst the osmolytes with respect to effects on protein stability. In addition, very little is known in regards to the molecular elements of the osmolytes themselves that are essential for their functions. In this study, we use differential scanning fluorimetry to quantify the thermal stabilizing effects of members from each of the three main classes of protecting osmolytes on two model protein systems, C-reactive protein and tumor necrosis factor alpha. Our data reveals the absence of a strict chemical class hierarchy amongst the osmolytes with respect to protein thermal stabilization, and indicates differential responses of these proteins to certain osmolytes. In the second part of this investigation we dissected the molecular elements of amino acid osmolytes required for thermal stabilization of myoglobin and C-reactive protein. We show that the complete amino acid zwitterion is required for thermal stabilization of myoglobin, whereas removal of the osmolyte amino group does not diminish stabilizing effects on C-reactive protein. These disparate responses of proteins to osmolytes and other small molecules are consistent with previous observations that osmolyte effects on protein stability are protein-specific. Moreover, the data reported in this study support the view that osmolyte effects cannot be fully explained by considering only the solvent accessibility of the polypeptide backbone in the native and denatured states, and corroborate the need for more complex models that take into account the entire protein fabric.

Changes in plasma renin activity in cirrhosis: a reappraisal based on studies in 67 patients and "low-renin" cirrhosis.

The generally held views that plasma renin activity (PRA) is increased in cirrhosis and that this is secondary to reductions in the "effective" blood or extracellular fluid (ECF) volumes, consequent on the effects of portal hypertension, were re-examined in the present study. Measurements of PRA in 67 patients representing different clinical stages of cirrhosis showed that the mean value in 15 patients without ascites was significantly reduced. In 21 of 35 with ascites, PRA was either reduced or within the normal range. A low plasma renin substrate concentration was not the cause for the low PRA. These findings are not in keeping with the concepts of reduced "effective" blood or ECF volumes at least for the majority of patients at these stages of cirrhosis under the conditions of the present study. The only group showing a significantly increased PRA had evidence of renal impairment. In these 17 patients the underlying reduction in renal perfusion may have been the stimulus to the kidney that led to an increase to renin secretion.

The histopathology of treated Barrett's esophagus: squamous reepithelialization after acid suppression and laser and photodynamic therapy.

Columnar metaplasia of the lower esophageal epithelium (Barrett's esophagus) occurs in response to acid reflux, and its most important long-term complication is malignancy. In view of this, techniques are being explored for the eradication of Barrett's esophagus, and histopathologists will increasingly be required to assess response to these therapies in esophageal biopsy samples. The histopathologic features before and after treatment were studied in biopsy samples from 16 patients receiving omeprazole only, 10 treated by KTP laser photoablation, and five who underwent photodynamic therapy. All the treatment modalities resulted in histologic changes with at least partial squamous reepithelialization of the metaplastic columnar epithelium. The histologic findings suggest three main mechanisms for this: encroachment of adjacent squamous epithelium at the squamocolumnar junction, extension of epithelium from the submucosal gland duct to form squamous islands, and squamous metaplasia within the Barrett's columnar mucosa itself. The latter mechanism implies the existence of pluripotential stem cells within Barrett's mucosa. A relatively common finding was residual glandular mucosa, nonneoplastic and dysplastic, beneath squamous epithelium indicating the requirement for histologic confirmation of endoscopically suspected complete squamous reepithelialization with sufficiently deep biopsies.

Medroxyprogesterone acetate does not perturb the profile of steroid metabolites in urine during pregnancy.

The plasma concentrations of medroxyprogesterone acetate (MPA) in 14 women administered the progestagen for threatened abortion during the first 6 weeks of pregnancy were measured by specific radioimmunoassay. Treatment (52 nmol orally every 6 h) was continued to 18 weeks of gestation. The mean plasma concentration of MPA rose rapidly during day 1 of treatment to 14.1 +/- 1.84 nmol/l. It reached 21.5 +/- 2.3 nmol/l by 7 days and subsequently stabilized at around 26.8 +/- 5.0 nmol/l by the end of week 2. Urinary steroid profiles were determined by gas-liquid chromatography and mass spectrometry for six of the MPA-treated women and compared with those of six untreated women of similar gestational age. No differences were detected between the two groups of women, suggesting that the administration of MPA during pregnancy did not alter qualitatively or quantitatively the metabolism and excretion into urine of progesterone and oestrogens.

Regression of columnar-lined (Barrett's) oesophagus with omeprazole 40 mg daily: results of 5 years of continuous therapy.

BACKGROUND: We have previously reported the effect of 2 years of omeprazole 40 mg daily on columnar-lined (Barrett's) oesophagus (CLO). AIMS: In the present study, follow-up has been extended to 5 years to assess the macroscopic and microscopic effects of continuing therapy. PATIENTS AND METHODS: The 23 patients have been followed for up to a further 3 years. Endoscopy with multiple biopsies was performed at the end of years 3, 4 and 5. RESULTS: Although there had been a statistically significant regression in the length of CLO after 2 years, there was no overall further measurable change after 5 years. However, one patient showed complete macroscopic and microscopic regression. The number and size of macroscopic squamous islands within the CLO continued to increase, and there was a further increase in microscopic squamous re-epithelialization of surface mucosa, gland ducts and Barrett's gland tissue. Low-grade dysplasia was found consistently in one patient in biopsies taken up to the end of year 3 but it could not be detected thereafter. CONCLUSIONS: Omeprazole 40 mg daily appears to have beneficial effects on CLO, although it rarely induces a complete regression. Whether the benefits will reduce the risk of malignant transformation is unknown.

An Eudragit-coated prednisolone preparation for ulcerative colitis: pharmacokinetics and preliminary therapeutic use.

Prednisolone metasulphabenzoate, a steroid with poor colonic absorption, was coated with the pH-dependent acrylic resin Eudragit S, as a means of delivering an orally administered preparation to the proximal colon. The therapeutic potential of delivering this steroid with potentially less systemic side-effects to the proximal colon was assessed in extensive ulcerative colitis. Plasma and urine prednisolone profiles in 6 healthy volunteers confirmed minimal absorption from Eudragit S-coated prednisolone metasulphabenzoate compared to prednisolone acetate: peak plasma prednisolone concentrations 29 +/- 21 ng/ml vs. 570 +/- 185 ng/ml (P less than 0.01), area under curve measurements 204 +/- 214 vs. 2724 +/- 1236 ng.h/ml (P less than 0.01). Prednisolone metasulphabenzoate coated with Eudragit S (30-60 mg daily) was then administered for 12 weeks to 12 patients with colonoscopically proven extensive ulcerative colitis in relapse. Symptoms, sigmoidoscopic appearances and rectal histological abnormalities all improved during therapy. Complete clinical remission occurred in 7 patients, a partial response in 2 patients and no response in 3 patients. Cortisol responses to tetracosactrin demonstrated no significant adrenal suppression following treatment. Eudragit S-coated prednisolone metasulphabenzoate may be a useful treatment for extensive ulcerative colitis, without risk of systemic steroid side-effects.

Preservation of gastric antral mucus is associated with failure of eradication of Helicobacter pylori by bismuth, metronidazole and tetracycline.

METHODS: Forty-three patients positive for Helicobacter pylori by histology and culture of antral biopsies (n = 40) or histology alone (n = 3) were investigated. They received either regimen 1--tripotassium dicitrato bismuthate 120 mg q.d.s. and tetracycline 250 mg q.d.s. for 4 weeks, with metronidazole 200 mg q.d.s. for the first 2 weeks, or regimen 2--omeprazole 20 mg b.d., amoxycillin 500 mg t.d.s., tetracycline 500 mg q.d.s. each for 3 weeks. Gastric antral biopsies were scored (0-3) histologically for mucus depletion, polymorphonuclear and mononuclear cell infiltrate. H. pylori eradication was assessed by biopsy and culture 1 month after the cessation of treatment. RESULTS: With regimen 1, pre-treatment mucus depletion was significantly higher where eradication was successful (median score 2) compared to where it was not (median score 1, P < 0.01); there were no differences in the scores for polymorphonuclear or mononuclear cell infiltrates. In patients receiving regimen 2, there were no differences in either mucus depletion or polymorphonuclear or mononuclear cell infiltrate, between those where eradication was successful and those where it was not. Metronidazole minimum inhibitory concentrations rose when eradication with regimen 1 was unsuccessful (median before 0.19 mg/L, median after treatment 16 mg/L; P = 0.04). CONCLUSION: Pre-treatment mucus depletion is identified as a factor affecting H. pylori eradication. Preservation of mucus may facilitate acquisition of metronidazole resistance.

Symptom relief and duodenal ulcer healing with omeprazole or cimetidine. Opus (Omeprazole Peptic Ulcer Study) Research Group.

In a double-blind parallel-group study, 98 patients with symptomatic duodenal ulcer received omeprazole 20 mg o.m. and 91 cimetidine 800 mg nocte for 2 or, if then not healed, 4 weeks. After 2 weeks the healing rates on an intention-to-treat basis were: for omeprazole 62% and for cimetidine 33% (P less than 0.001), and at 4 weeks 85% and 61%, respectively (P less than 0.001). The proportions symptom-free at 2 weeks were 83% of the omeprazole and 63% of the cimetidine-group (P less than 0.01) and at 4 weeks 84% and 72% (P = 0.01). Patients receiving omeprazole took fewer antacid tablets than those receiving cimetidine. Patient tolerance of both drugs was similar and good. In the treatment of duodenal ulcer, omeprazole 20 mg o.m. gives faster symptom relief than cimetidine 800 mg nocte, as well as healing a greater proportion of ulcers within 2 and 4 weeks.

Regression of columnar lined (Barrett's) oesophagus with continuous omeprazole therapy.

Twenty-three adult patients with a columnar lined (Barrett's) oesophagus are being treated with long-term omeprazole, 40 mg daily. Twelve had never undergone anti-reflux surgery (Group 1), the other eleven having previously had insertion of an Angelchik anti-reflux prosthesis (Group 2). Endoscopy was carried out six months before, immediately before and six months, one year and two years into treatment. Multiple and standardized biopsies were taken at each endoscopy. Results from the two groups were similar. During the 6-month run-in period there was a statistically non-significant increase in the linear extent of the columnar mucosa, but this showed a progressive, statistically significant decrease during the two years of treatment. Other evidence for regression of the Barrett's mucosa includes the emergence of large numbers of macroscopic squamous islands within the abnormal mucosa, an increase in the number of microscopic squamous islands, and microscopic squamous encroachment of the abnormal mucosa at the squamo-columnar junction. Histological assessment showed a reduction in the proportion of sulphomucin-rich intestinal metaplasia, but this only achieved statistical significance in Group 1. The results substantiate the importance of acid in the pathogenesis of Barrett's oesophagus. Omeprazole may have a therapeutic role in bringing about regression of the metaplastic epithelium.

Biologic variation of common hematologic laboratory quantities in the elderly.

Analytic, within-subject, and between-subject biologic variations were estimated for leukocytes, erythrocytes, hemoglobin, hematocrit, mean cell volume (MCV), mean cell hemoglobin (MCH), mean cell hemoglobin content (MCHC), platelets, and a three-component differential count (lymphocytes, monocytes, and granulocytes in terms of both concentration and percentage of leukocytes) in cohorts of 12 male and 12 female healthy elderly subjects. The assays were performed with an Ortho ELT-800 automated analyzer. The estimates of within-subject biologic variation were similar to published data on young subjects, indicating that this aspect of homeostasis is not compromised in the elderly. The data were used to derive objective analytic goals; goals were surpassed except for assays of erythrocytes, hematocrit, and the derived MCV, MCH, and MCHC. The changes required for serial results to be significantly different were determined and found to be generally valid because most quantities have no heterogeneity of within-subject variation. All quantities had significant individuality; in consequence, conventional population-based reference values are of limited utility, and screening using reference limits will not detect latent or early disease in many subjects.

Spectrum of renal tubular damage in renal failure secondary to cirrhosis and fulminant hepatic failure.

Measurements of urinary lysozyme were used to evaluate renal tubular integrity in 34 patients with cirrhosis or fulminant hepatic failure who had developed renal impairment. In 18 of the patients the lysozyme values were normal but in the remaining 16 were increased, supporting previous concepts that renal failure complicating hepatocellular disease may occur both without and with tubular necrosis. The lysozyme values were inversely related to the creatinine clearance, suggesting that the development of tubular necrosis may be determined by the level of renal perfusion. The validity of simpler laboratory tests often used to assess renal tubular integrity--namely, the urine sodium concentration, the urine:plasma osmolality ratio, and casts in the urine sediment--was evaluated by comparison with the lysozyme measurements. The urine sodium concentration was of most value and the findings in the sediment were of no value at all.

Frequency of renal impairment in paracetamol overdose compared with other causes of acute liver damage.

In an analysis of 160 patients with fulminant hepatic failure, the frequency of renal failure in the patiens who had taken an overdose of paracetamol was not significantly higher than in those with hepatic failure due to other causes. The same was found in another group of patients with less severe hepatic damage. In both the latter group and the patients with fulminant hepatic failure, the development of renal failure was closely related to the occurrence of endotoxaemia as detected by the Limulus lysate assay. These findings do not support the concept that an overdose of paracetamol has a specific nephrotoxic effect.

New spiral bacterium in gastric mucosa.

A new spiral bacterium, distinct from Campylobacter pylori, was found in the gastric mucosa of six patients with gastrointestinal symptoms. All patients had chronic active type B gastritis and four had oesophagitis. Culture and microscopy for C pylori infection was negative. These unculturable spiral organisms were probably an incidental finding in patients presenting for upper gastrointestinal endoscopy, but it is not possible to say from this small series whether these organisms cause chronic active gastritis. The organism is helical, 3.5-7.5 microns long and 0.9 micron in diameter with truncated ends flattened at the tips, and up to 12 sheathed flagella 28 nm in diameter at each pole. It is proposed that this spiral bacterium should be called "Gastrospirillum hominis Gen.nov., Sp.nov."

Quantitation of organic acids in amniotic fluid by gas chromatography.

The concentrations of 13 major organic acids in normal human amniotic fluid have been determined by gas chromatography. Each acid showed a large range and an irregular frequency distribution.

Urinary steroid profiles in pregnancy by capillary column gas chromatography.

A qualitative and quantitative method for the estimation of urinary steroids during pregnancy by capillary column gas chromatography has been developed. Steroid conjugates were hydrolysed by enzymes and free steroids isolated by extraction using SEP-PAK C18 cartridges. Methoxime-trimethylsilyl derivatives of the steroids were characterized by packed column gas chromatography-mass spectrometry and subsequently by their retention indices on capillary column gas chromatography. Of the 48 peaks resolved on the profiles about 35 were identified as steroids. The retention indices of reference steroids were very reproducible in the short term showing a mean coefficient of variation of 0.015%. The columns allowed 95% valley resolution of steroids whose retention indices differed by only 7 units. The use of an on-column injection technique contributed to the high precision for replicate injections (coefficient of variation less than 1%) while for reference steroids, and well-resolved peaks in the urine profile, the mean coefficient of variation for the complete assay was less than 10%. To the best of our knowledge this is the first report concerning the quantitation, with good precision, of a large number of steroids in pregnancy urine.

Organic acids in amniotic fluid.

The organic acids of human amniotic fluid were studied by gas chromatography and mass spectrometry. About 30 acids were identified. A "normal" metabolic profile of acids was established which can provide the basis for the identification of abnormal patterns.

Prenatal diagnosis of X-linked ichthyosis.

Prenatal diagnosis of X-linked ichthyosis in a case of steroid sulfatase deficiency was made at 16 weeks by the demonstration of (1) high levels of dehydroepiandrosterone sulfate in amniotic fluid; (2) gross deficiency of steroid sulfatase activity in cultured amniotic fluid cells; (3) very low estriol concentrations in maternal blood and urine; (4) increased maternal plasma dehydroepiandrosterone sulfate; and (5) a characteristic maternal urinary steroid profile with greatly increased levels of 16 alpha-hydroxydehydroepiandrosterone. The latter method is particularly useful since it requires no invasive procedures for the patient and is very specific.

3-Hydroxy-3-methylglutaric aciduria, combined with 3-methylglutaconic aciduria.

1. A baby with severe metabolic acidosis was found to excrete abnormal amounts of 3-methylcrotonic acid, 3-methylglutaconic acid and 3-hydroxy-3-methylglutaric acid in urine. 2. Several other abnormal constitutents appear to be products of side-reactions and include 3-hydroxy-3-methylbutyric acid and 3-methylglutaric acid. 3. The profile of acids in urine indicates a blockage in the sixth step of leucine catabolism, the cleavage of 3-hydroxy-3-methylglutaryl-CoA to acetoacetic acid and acetyl-CoA.

Hormone-sensitive gene expression in breast tumours.

The expression of genes specifically induced by estrogens (pS2), prolactin (PIP) or progestins (Pg8) was measured in primary breast tumours. A highly augmented pS2 gene expression was evident in 55% of estrogen receptor (ER)+, progesterone receptor (PR)+ tumours but was absent in ER- PR- tumours. There was no clear cut correlation between augmented levels of PIP and Pg8 mRNAs in tumours and ER and PR status. Tumours from premenopausal patients were more likely to contain high levels of Pg8 mRNA (P less than 0.038), whereas tumours from postmenopausal patients tended to have augmented levels of PIP mRNA (P less than 0.053).

Treatment options for cirrhotic ascites.

Ascites due to cirrhosis can usually be managed successfully by dietary sodium restriction and carefully monitored diuretic therapy. However, paracentesis with an albumin infusion is a relatively safe alternative that has gained widespread acceptance. Other plasma expanders offer a cheaper alternative to albumin. Other recently developed techniques include peritoneovenous shunt and transjugular intrahepatic portosystemic stent shunt. Each of these is associated with an operative mortality and substantial complications, but for diuretic-resistant ascites a peritoneovenous shunt has comparable results to paracentesis/albumin. For patients with spontaneously occurring renal failure the prognosis is poor. None of the above treatments improves renal function. Management should therefore be symptomatic with paracentesis as necessary.