Floristic diversity and co-occurrences in a subtropical broad-leaved forest and two contrasting regrowth stands in central-west Yunnan Province,China

Many of the natural forested ecosystems that still remain in mainland China are being cleared with potentially detrimental effects on woody plant species diversity on both local and regional scales. The most extensive stand of subtropical broad-leaved forest remaining in China is located in Yunnan Province. In an effort to document the influence of human-induced disturbance on Yunnan's woody flora, floristic inventories were conducted in a stand of primary forest and in regrowth stands located in its interior and along its outer margin in the Xujiaba Nature Sanctuary in the Ailao Mountain Range. Of particular interest was the location of the disturbance relative to the primary forest source area. A total of 134 woody plant species representing 74 genera and 43 families were recorded. The floristics of the two regrowth stands were significantly different from each other, with < 10% of their respective floras comprised of co-occurring species. The interior regrowth stand had a higher number of co-occurring species with the primary forest; however, > 40% were still non-co-occurring.The principal families represented in the primary forest and the interior regrowth stand were Aquifoliaceae, Berberidaceae, Fagaceae, Lauraceae, Rosaceae, Smilacaceae, Symplocaceae, Theaceae, and Vacciniaceae. The three dominant species with relative importance values ranging from > 5% to 18% in both the primary forest and the interior regrowth stand were Castanopsis wattii, Lithocarpus jingdongensis, and Symplocos sumuntia. The edge regrowth stands had the lowest species diversity and were dominated by the native pine Pinus yunnanensis, with a relative importance of 24%. The principal families represented in the edge regrowth stand were Betulaceae, Ericaceae, Fagaceae, Myricaceae, Pinaceae, and Theaceae. Only the Fagaceae and Theaceae were well-represented in all three stands. The results of the study document the low species diversity in post-cutting regrowth on the margins of the primary forest as compared with post-cutting regrowth in the forest interior.     

RAPD typing of clinical isolates of Staphylococcus haemolyticus

The randomly amplified polymorphic DNA (RAPD) assay was used to generate DNA fingerprints from clinical isolates of Staphylococcus haemolyticus isolated from patients treated with continuous ambulatory peritoneal dialysis and previously subjected to a combination of typing methods. The RAPD profiles generated with one of six randomly designed 10-mer primers allowed visual discrimination of strains. Good correlation with the original typing scheme was achieved but RAPD typing allowed discrimination of strains previously indistinguishable.     

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.     

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.