Comparison of prevalence of schizophrenia among residents of hostels for homeless people in 1966 and 1992.

OBJECTIVE--To determine whether the prevalence of schizophrenia among the homeless population of Edinburgh resident in hostels has changed between 1966 and 1992. DESIGN--Comparison of two cross sectional surveys. SETTINGS--Hostels for homeless people in Edinburgh. SUBJECTS--In 1966 a random sample of 98 residents of three common lodging houses. In 1992 a random sample of 198 residents of nine hostels. MAIN OUTCOME MEASURE--Prevalence of schizophrenia. RESULTS--The prevalence of schizophrenia in 1992 was 12/136 (9%) compared with 20/79 (25%) in 1966 (odds ratio 0.29; 95% confidence interval 0.13 to 0.62; P = 0.001). Adjustment for confounding by age, current hostel, and duration of unemployment by means of logistic regression produced an adjusted odds ratio of 0.22 (0.08 to 0.58). CONCLUSIONS--The prevalence of schizophrenia was lower in 1992 even after other changes in the population resident in hostels occurring between 1966 and 1992 were taken into account. The findings are not consistent with an increase in the prevalence of schizophrenia among homeless people despite a 66% reduction in adult psychiatric beds in the region during 1966-92.     

Production and initial characterisation of the xylan-degrading system of Phanerochaete chrysosporium

We report the optimum conditions for the degradation of oat spelt arabinoxylan and a preliminary characterisation of the inducible xylan-degrading system of the lignin-degrading white-rot fungus Phanerochaete chrysosporium. Xylanase activity was optimal at pH 5.0 and 50°C; see attached sheet the maximum reaction velocity (V_max) of the system was 3.86 units (U) mg^–1 protein with arabinoxylan as substrate and the substrate concentration giving half V_max (S_0.5) was 0.52 mg ml^–1. At concentrations of arabinoxylan greater than 15 mg ml^–1 excess substrate inhibition was observed. Xylose at 0.9 mm inhibited activity to the extent of 50%. Xylanase activity increased as a function of the dilution of the enzyme preparation prior to assay. It was resolved into four peaks by using a DEAE-Biogel column; the material in these peaks differed with respect to xylan solubilisation and the formation of reducing sugars. Electrofocusing gels allowed visualisation of several bands of activity corresponding to each peak. The arabinoxylan degradation system of P. chrysosporium is therefore composed of multiple components. Correspondence to: P. Broda     

Sterilization of various diameter dead-ended tubes

Effect of tube diameter on steam-in-place sterilization of dead-ended tubes was studied by examining temperature profiles and rates of kill of Bacillus stearothermophilus spores. Time required for sterilization was determined for 9.4-cm-long tubes with various inside diameters from 0.4 to 1.7 cm. Sterilization time increased with decreasing tube diameter. Experimentally measured kill kinetics in 1.7-cm tubes were in agreement with those predicted if measured temperatures represented saturated steam. A 12-log spore reduction was achieved in 1.7-cm diameter vertical and horizontal tubes in less than 63 minutes. For smaller diameter tubes, entrapped air remained after 2 hours and rates of kill were very dependent on position within the tube, tube diameter, and tube orientation with respect to the gravitational vector. Times to achieve a 1-log drop in spore population in the smaller tubes were as much as 10 times greater than those expected if measured temperatures represented saturated steam. Sterilization was not achieved throughout the 0.4-cm tubes. Recommendations are made for including steam bleeders or using prevaccum cycles for these smaller diameter tubes. (c) 1993 John Wiley & Sons, Inc.     

Cultivation of mammalian cells as aggregates in bioreactors: effect of calcium concentration of spatial distribution of viability

Recombinant human kidney epithelial 293 cells were cultivated as aggregates in suspension. The concentration calcium ion, in the range of 100 muM to 1mM, affected the rate of aggregate formation. During the course of cultivation the size distribution of aggregates shifted and the fraction of larger aggregates increased. This effect was more profound in cultures with a high calcium concentration. Scanning and transmission microscopic examination of the aggregates revealed that cell packing was greater in the high calcium cultures and that ultrastructural integrity was retained in aggregates from both low and high calcium cultures. Confocal microscopy was applied to examine the viability of cells in the interior of the aggregates. High viability was observed in the aggregates obtained from exponentially growing cultures. Aggregates from the high calcium culture in the stationary phase exhibited lower viability in the interior. With its ease of retention in a perfusion bioreactor, aggregate cultures offer an alternative choice for large-scale operation. (c) 1993 John Wiley & Sons, Inc.     

Colestipol-induced changes in LDL composition and metabolism. II. Studies in humans

We investigated the effect of the bile acid sequestrant, colestipol hydrochloride, on the composition and metabolism of human low density lipoprotein (LDL). Colestipol treatment produced a disproportionate decrease in LDL cholesterol compared to LDL apoB, resulting in a significant decrease in the LDL cholesterol/apoB ratio. Electron microscopy revealed that LDL particles were smaller in size and analytical ultracentrifugation demonstrated that colestipol therapy selectively depleted larger, more buoyant LDL particles of Sf degrees 6-7. Thus, colestipol therapy produced LDL that were smaller in size, more dense, and characterized by a decreased cholesterol to protein ratio. To determine whether the altered LDL had different metabolic properties, autologous LDL was isolated from subjects before and during colestipol therapy and their fractional catabolic rates (FCR) were then simultaneously determined in the same patient while on therapy. Eight LDL turnover studies comparing the catabolism of LDL isolated during therapy (Rx-LDL) and LDL isolated off therapy (Con-LDL) were performed in six subjects. All subjects responded to colestipol treatment, with an average 29% fall in LDL cholesterol. In four of six subjects, and in six of eight studies, the FCR of Rx-LDL was substantially slower than that of Con-LDL. These studies demonstrate that a drug intervention may alter subpopulations of LDL particles in such a way that overall LDL composition is changed. This alteration may independently affect the intrinsic metabolic behavior of the LDL. We suggest that such drug- (or dietary-) induced changes in LDL composition need to be considered in kinetic studies designed to assess the overall impact of the perturbation being studied.     

Proton nuclear magnetic resonance spectroscopy of isolated rabbit fundic glands

1H-nuclear magnetic resonance spectroscopy (NMR) was adapted to isolated rabbit fundic glands and identification made of compounds responsible for several observed spectral resonances. A minimum gland concentration of 0.5 mg dry weight or 5 mg wet weight per 0.5 ml was needed for adequate signal-to-noise ratio. At physiological temperature and pH, the glands demonstrated reproducible spectra, stability for accumulation times greater than 30 min and responsiveness to histamine stimulation, as measured by oxygen consumption and aminopyrine uptake. The relatively anaerobic conditions favored use of proton compared to phosphorus NMR, since 1H-NMR allowed significantly shorter spectral accumulation times and therefore did not compromise glandular viability to the same extent as 31P-NMR. The most conspicuous resonance in the gland spectrum was assigned to the -N+(CH3)3 protons of choline and related compounds. In membrane-free lysates, several components of the signal were resolvable and assigned to choline, phosphatidylcholine, phosphocholine and L-alpha-glycerophosphocholine. Thin-layer chromatography verified that phosphatidylcholine and phosphatidylethanolamine were the major phospholipids present in gland lipid. Presumably, they represent the source of the surface-active phospholipids present in gastric juice, which may play a role in gastric cytoprotection.