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.     

Exclusion mapping of the gene for X-linked neural tube defects in an Icelandic family

Various polymorphic markers with a random distribution along the X chromosome were used in a linkage analysis performed on a family with apparently Xlinked recessive inheritance of neural tube defects (NTD). The lod score values were used to generate an exclusion map of the X chromosome; this showed that the responsible gene was probably not located in the middle part of Xp or in the distal region of Xq. A further refining of these results was achieved by haplotype analysis, which indicated that the gene for X-linked NTD was located either within Xp21.1-pter, distal from the DMD locus, or in the region Xq12–q24 between DXS106 and DXS424. Multipoint linkage analysis revealed that the likelihood for gene location is highest for the region on Xp. The region Xq26–q28, which has syntenic homology with the segment of the murine X chromosome carrying the locus for bent tail (Bn), a mouse model for X-linked NTD, is excluded as the location for the gene underlying X-linked NTD in the present family. Thus, the human homologue of the Bn gene and the present defective gene are not identical, suggesting that more than one gene on the X chromosome plays a role in the development of the neural tube.     

Correlation ofLegionella pneumophila virulence with the presence of a plasmid

Legionella pneumophila is the causative agent of Legionellosis in man and considered an opportunistic intracellular Gram-negative bacterium that preferentially infects macrophages. The presence of a plasmid in these organisms was determined in cultures of the bacteria grown in vitro. A correlation was observed between the growth of virulent strains of theLegionella in murine macrophages and growth on standard buffered charcoal yeast extract agar supplemented with 0.1% -ketoglutarate (BCYE) agar medium rich in cysteine and widely used for growth of the bacteria in vitro. In contrast, the avirulent isolates of these strains grew well on supplemented Mueller-Hinton (SMH) agar utilized for differentiating virulent from avirulentLegionella. However, one virulent strain ofLegionella (the Iowa strain) was found to grow moderately well on the SMH agar. In addition, test strains ofLegionella that infect in vitro human monocytes were found to grow moderately well on the BCYE- agar, but did not grow on the SMH agar. Examination of these strains for plasmid DNA expression showed that extra chromosomal DNA-containing molecules were present in theL. pneumophila strains characterized as virulent for in vitro growth in macrophages. However, the avirulent strains that replicated in the human monocytes readily but only poorly in the permissive murine macrophages did not show evidence of similar plasmid DNA expression.     

The feeding rates ofPleurobrachia (ctenophora) andSagitta (chaetognatha), with notes on the potential seasonal role of planktonic predators in the dynamics of north sea zooplankton communities

The zooplankton off the north-east coast of England has been the subject of a number of studies focusing on its productivity. It has also been shown to be representative of the zooplankton of much of the western North Sea. The community contains a number of predatory species, three of which are widely described as ‘voracious’, the ctenophorePleurobrachia pileus, the chaetognathSagitta elegans and the hyperiid amphipodThemisto compressa (≡ Parathemisto gaudichaudi). This study investigates the role of these planktonic predators in this community, with special reference to the seasonal changes in predation pressure. The functional response ofPleurobrachia pileus feeding onAcartia was determined from laboratory experiments. It was found to be linear at prey densities typical of UK coastal waters, although the linear relationship appeared to break down at low and high prey densities. Feeding rate data forSagitta elegans were obtained from gut content analysis and published laboratory derived estimates of digestion time. Of the 1,789 individuals examined 198 (11.1%) had food remains in the gut. A linear relationship betweenSagitta length and prey size was established and the daily feeding rate ofSagitta elegans was estimated to be 0.4 prey items d⁻¹ ind⁻¹. For comparative purposes, the proportion of the copepod standing stock removed bySagitta elegans, Pleurobrachia pileus andThemisto gaudichaudi was estimated for each month of the year. From this model it was shown thatThemisto applied the most predation pressure, andSagitta elegans applied the least predation pressure of the three planktonic predators considered. The impact ofPleurobrachia will be to a large extent offset due to its peak of seasonal abundance coinciding with the zooplankton peak in the summer.     

Low-molecular-weight thiols in streptomycetes and their potential role as antioxidants.

The intracellular low-molecular-weight thiols present in five gram-positive Streptomyces species and one Flavobacterium species were analyzed by high-performance liquid chromatography after fluorescence labeling with monobromobimane. Bacteria were chosen to include penicillin and cephalosporin beta-lactam producers and nonproducers. No significant amount of glutathione was found in any of the streptomycetes. Major intracellular thiols in all strains examined were cysteine, coenzyme A, sulfide, thiosulfate, and an unknown thiol designated U17. Those streptomycetes that make beta-lactam antibiotics also produce significant amounts of delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV), a key intermediate in their biosynthesis. In Streptomyces clavuligerus, a potent producer of beta-lactams, the level of ACV was low during the early phase of growth and increased rapidly toward the end of exponential growth, paralleling that of antibiotic production. These and other observations indicate that ACV does not function as a protective thiol in streptomycetes. U17 may have this role since it was the major thiol in all streptomycetes and appeared to occur at levels about 10-fold higher than those of the other thiols measured, including ACV. Purification and amino acid analysis of U17 indicated that it contains cysteine and an unusual amine that is not one of the common amino acids. This thiol is identical to an unknown thiol found previously in Micrococcus roseus and Streptomyces griseus. A high level of ergothioneine was found in Streptomyces lactamdurans, and several unidentified thiols were detected in this and other streptomycetes.     

Body condition of a small passerine bird: ultrasonic assessment and significance in overwinter survival

The fitness benefits of intraspecific variation in physiological attributes have rarely been measured. Body condition, defined as the current status of metabolic reserves relative to likely demands, has often been implicated in subsequent survival, but has proved difficult to assess reliably in the live animal. A technique for assessing body condition, in terms of the main protein reserve of small birds, is presented. Pectoralis muscle thickness was measured in live birds using ultrasound reflection from the sternum. The relationship between the relative size of pectoralis muscles in autumn and the likelihood of overwinter survival in the dipper Cinclus cinclus was examined. The pectoralis reserves of male dippers surviving overwinter were significantly greater than those of birds which died or disappeared between late November and the breeding season in April. In contrast, variation in autumn condition of females was unrelated to overwinter survival.     

Changes in human jaw muscles with age and dental state

The effects of ageing and dental state on the cross-sectional area and density of two jaw muscles, the masseter and medial pterygoid, were investigated using computed tomography. The study involved 84 male and 70 female subjects between the ages of 20 and 90 years. The cross-sectional area of both muscles showed a significant reduction with age; values for female subjects being found in the lower range of the distribution. When consideration was given to the presence or absence of a natural dentition, the cross-sectional area of both muscles in edentulous subjects showed a greater decease throughout the age range studied. There was a significant decrease in the density of the muscles with increasing age. Previously, this has been interpreted to indicate a progressive increase in fat and fibrous tissue. Subject gender and the absence of teeth appeared to have little effect on this parameter. Changes in the cross-sectional area and density of these muscles would appear to be consistent with a general age related change of muscle tissue in the body as a whole and may specifically indicate a reduction in the masticatory forces which can be or are being utilised by ageing patients, many of whom have no remaining natural dentition.     

para-sulfobenzoyloxybromobimane: a new membrane-impermeable reagent useful for the analysis of thiols and their export from cells.

para-Sulfonylbenzoyloxybromobimane (sBBr) was shown to be similar to the fluorescent labeling agent monobromobimane (mBBr) in reacting rapidly and selectively with thiols to produce stable derivatives which are readily separated by HPLC. Chromatography of the sBBr derivative provides a useful means of confirming the identification of an unknown thiol based upon the chromatography of its mBBr derivative and can be useful for quantitative determination of polycationic thiols for which chromatography of the mBBr derivative is unsatisfactory. Unlike mBBr, which readily penetrates cells, sBBr was found not to be taken up by cells. These characteristics allow sBBr to be used, in conjunction with mBBr, to quantify the export of thiols from cells, as illustrated for GSH and the radioprotective drug WR1065, from V79 cells. Simultaneous determination of GSH and glutathione disulfides in cell culture medium could be achieved by labeling of thiols with sBBr followed by reduction of disulfides with dithiothreitol, labeling of the resulting thiols with mBBr, and HPLC analysis for both glutathione derivatives.     

The Total Chemical Synthesis of Monocyte Chemotactic Protein-1 (MCP-1)

The affinity-based N^α-amino protecting group tetrabenzo [a,c,g,i]fluorenyl-17-methoxycarbonyl (Tbfmoc) has been utilized as a hydrophobic probe to allow the simple, quick and highly effective isolation of a 76 residue cysteine-containing protein (MCP-1). The base-labile Tbfmoc group can be removed under very mild conditions, which preserve the thiol-con taining protein in the reduced state. Oxidative folding was then used to furnish the biologically active β-chemokine MCP-1.     

Identification of a novel response regulator required for the swarmer-to-stalked-cell transition in Caulobacter crescentus.

The onset of motility late in the Caulobacter crescentus cell cycle depends on a signal transduction pathway mediated by the histidine kinase PleC and response regulator DivK. We now show that pleD, whose function is required for the subsequent loss of motility and stalk formation by the motile swarmer cell, encodes a 454-residue protein with tandem N-terminal response regulator domains D1 and D2 and a novel C-terminal GGDEF domain. The identification of pleD301, a semidominant suppressor of the pleC Mot phenotype, as a mutation predicted to result in a D-53-->G change in the D1 domain supports a role for phosphorylation in the PleD regulator. Disruptions constructed in the pleD open reading frame demonstrated that the gene is not essential and that the pleC phenotype can also be suppressed by a recessive, loss-of-function mutation. These results suggest that PleD is part of a signal transduction pathway controlling stalked-cell differentiation early in the C. crescentus cell cycle.