On non-metric multidimensional scaling ordination and interpretation of the matorral vegetation in lowland Murcía

The plant-environment relationships in a range of matorral communities, having different rainfall conditions in semi-arid lowland habitats in Murcía, S.E. Spain, were examined using the non-metric multidimensional scaling ordination technique. Hypotheses on floristic variations were derived based on an interpretative strategy which involved a site configuration rotation, followed by stepwise multiple regression analysis. An environmental data set was used to isolate variables associated with site co-ordinate trends. Results showed that floristic variation in these communities was mainly determined by aspect induced radiation receipt. Besides, most environmental trends in the study areas were found to be oblique to original site ordination axes and configuration rotation seemed to be a prerequisite in quantitative interpretation. The interpretative strategy introduced in this study was effective. It enhanced straightforward, quantitative and objective interpretation whereby inductive inferences on environmental trends could be readily formulated.Abbreviations ARAD radiation receipt surrogate - DEPTH soil depth - DISTURB disturbance index - NMDS non-metric multidimensional scaling - NUT nutrient scalar - SLOPE slope angle - TEXTIN texture index     

Antioxidant drug mechanisms: transition metal-binding and vasodilation

In our work evaluating the antioxidant properties of a number of cardiovascular drugs, we have emphasized the importance of lipophilicity as a property contributing to antioxidant potency. Thus, the dihydropyridine calcium channel blockers and propranolol, one of the most lipophilic beta-blockers, were found to exhibit the greatest potency in membrane and cellular models. Both beta-blockers and calcium channel blockers are classified as antihypertensive agents. We found that the specific chemical moieties of various drugs may participate in the antioxidant mechanism of action. While reviewing relevant work from the past literature, it became apparent that some of the chemical moieties of antihypertensive and vasodilator drugs may bind transition metals. Thus, this present review focuses on common properties of transition metal-interaction that are shared, to a greater or lesser degree, by a number of vasoactive drugs and chemical agents. Although this observation has been pursued by other investigators in the past, we submit that the potential relevance to the newer pharmacological agents needs to be explored further. In addition, new information regarding the role of transition metals and free radicals involving vascular cells focuses greater importance on transition metal-interaction as a potential mechanism in vasodilation. This review does not intend to be inclusive of all chemical structures capable of binding transition metals; only those that are clinically relevant will be considered in some detail. Potential mechanisms of metal-chelating actions leading to vasodilation are also discussed.     

A genetic study of the human low-voltage electroencephalogram

Summary The studied phenotype, the low-voltage electroencephalogram (LVEEG), is characterized by the absence of an alpha rhythm from the resting EEG. In previous studies, evidence was found for a simple autosomal-dominant mode of inheritance of the LVEEG. Such a polymorphism in brain function can be used as a research model for the stepwise elucidation of the molecular mechanism involved in those aspects of neuronal activity that are reflected in the EEG. Linkage with the variable number of tandem repeats (VNTR) marker CMM6 (D20S19) and localization of an LVEEG (EEGV1) gene on 20q have previously been reported, and genetic heterogeneity has been demonstrated. This latter result has been corroborated by studing new marker (MS214). The phenotype of the LVEEG is described here in greater detail. Its main characteristic is the absence of rhythmic alpha activity, especially in occipital leads, whereas other wave forms such as beta or theta waves may be present. Analysis of 17 new families (some of them large), together with 60 previously described nuclear families, supports the genetic hypothesis of an autosomal-dominant mode of inheritance. Problems connected with the analysis of linkage heterogeneity, exclusion mapping, and the study of multipoint linkage are discussed. A possible explanation of the localization of LVEEG in the close vicinity of another gene influencing synchronization of the normal EEG, the gene for benign neonatal epilepsie, is given.     

Construction and characterization of a region-specific microdissection library from human chromosome 2q35-q37.

A region-specific genomic library for human chromosome 2q35-q37 has been constructed using the microdissection and polymerase chain reaction-mediated linker-adaptor microcloning method. Twenty fragments from the chromosome region 2q35-q37 were dissected and a library consisting of 20,000 recombinant microclones was obtained. The insert size ranged between 50 and 800 bp, with a mean of approximately 270 bp. About 50-60% of the microclones contained unique sequences. The microdissection library has been demonstrated to derive from the dissected region 2q35-q37 by chromosome painting using the fluorescence in situ hybridization (FISH) technique. Southern blot analysis of the unique sequence microclones from the library showed that 54% (26/48) of the clones are of human origin and chromosome 2 specific. Four of these microclones have been further mapped to the 2q37 region by using a cell hybrid containing only 2q37. The unique sequence microclones have also been characterized for their insert size and the hybridizing genomic fragments cleaved with HindIII. As shown previously, these microclones will be useful in isolating corresponding yeast artificial chromosome (YAC) clones with large inserts for high-resolution physical mapping and also in screening cDNA libraries to isolate expressed gene sequences as candidate genes to facilitate search for the crucial genes underlying genetic diseases and specific forms of cancer assigned to the region.     

若干种枝角类卵鞍表面亚显微结构的比较研究

以扫描电镜对发头裸腹溞、蚤状溞、隆线溞指名亚种以及隆线溞东湖一亚种的卵鞍分别进行了比较研究,发现卵鞍表面的亚显微结构有明显的差异,但亚种之间差异较小。隆线溞指名亚种与隆线溞东湖一亚种二者的卵鞍在光学显微镜下看不出有什么差异,然而亚显微结构却互不相同。这就为东湖一新亚种的确定提供了一项可靠的依据,同时也进一步证实卵鞍的超微结构确可作为枝角类分类的表征。     

新疆伊犁五个少数民族的近亲结婚

1983年4月至1984年5月,对新疆伊犁哈萨克自治州五个民族的近亲结婚情况进行了调查。调查的婚姻数为维吾尔2553起,哈萨克1079起,回1235起,锡伯1222起,蒙古446起。近亲结婚率与平均近交系数分别为:维吾尔——8.23％与 46.74×10~(-4),回——8.10％与45.07×10~(-4),锡伯——4.66％与24.93×10~(-4),哈萨克——2.87％与11.31×10~(-4)。蒙古——0.45％与 2.80×10~(-4)。解放以来,维吾尔族与回族的近亲结婚率有上升趋势,而锡伯族的则有下降趋势。各族近亲结婚中大部分为亲表亲结婚,但堂亲结婚在维吾尔族的近亲结婚中竟占26.18％,在回族中也占16.00％。1303名近亲结婚子女中的七岁前死亡率(12.89％)及先天性缺陷与遗传性疾病发生率(2.99％)显著高于6370名非近亲结婚子女的相应值(7.65％及0.38％)。     

The effect of metabolic acidosis on the synthesis and turnover of rat renal phosphate-dependent glutaminase.

Regulation of the mitochondrial phosphate-dependent glutaminase activity is an essential component in the control of renal ammoniagenesis. Alterations in acid-base balance significantly affect the amount of the glutaminase that is present in rat kidney, but not in brain or small intestine. The relative rates of glutaminase synthesis were determined by comparing the amount of [35S]methionine incorporated into specific immunoprecipitates with that incorporated into total protein. In a normal animal, the rate of glutaminase synthesis constitutes 0.04% of the total protein synthesis. After 7 days of metabolic acidosis, the renal glutaminase activity is increased to a value that is 5-fold greater than normal. During onset of acidosis, the relative rate of synthesis increases more rapidly than the appearance of increased glutaminase activity. The increased rate of synthesis reaches a plateau within 5 days at a value that is 5.3-fold greater than normal. Recovery from chronic acidosis causes a rapid decrease in the relative rate of glutaminase synthesis, but a gradual decrease in glutaminase activity. The former returns to normal within 2 days, whereas the latter requires 11 days. The apparent half-time for glutaminase degradation was found to be 5.1 days and 4.7 days for normal and acidotic rats respectively. These results indicate that the increase in renal glutaminase activity associated with metabolic acidosis is due primarily to an increase in its rate of synthesis. From the decrease in activity that occurs upon recovery from acidosis, the true half-life for the glutaminase was estimated to be 3 days.     

Randomised controlled trial of computer assisted management of hypertension in primary care.

The hypothesis that general practitioners would obtain better outcomes for patients with hypertension using a computer than doctors not using a computer was tested. Sixty family physicians were randomised to two treatment strategies. "Test" physicians completed a data collection form after each visit from a patient with hypertension and mailed the forms to the test centre for processing. Computer feedback on management was mailed to the doctors. This encouraged doctors to apply the "stepped care" protocol, supplied charts of diastolic blood pressure v time, and ranked patients'' diastolic blood pressures by percentile. Letters were mailed to patients to remind them of appointments. "Control" doctors filled out the same data collection forms as test physicians, but neither doctors nor patients received computer feedback. Physicians who used the computer saw more patients per practice than control doctors (test 50 patients, control 40). For all patients the length of follow up was significantly longer in test practices (test 199 days, control 167), and a smaller percentage dropped out of active treatment in test practices (test 37.5%, control 42.1%). For patients with "moderate" hypertension of a baseline diastolic pressure of greater than 104 mm Hg the mean score of the last recorded pressure was below the goal of 90 mm Hg in test practices (88.5 mm Hg), but it failed to reach this goal in control practices (93.3 mm Hg). A greater average reduction of diastolic pressure was achieved in test practices (test 21.7 mm Hg, control 16.7 mm Hg). Though patients with "moderate" hypertension were better controlled in test practices than in control practices, the patients in test practices visited their doctors less often (test 13.3 visits per patient-year, control 17.4 visits). Among patients with newly detected hypertension test practices achieved a greater reduction in diastolic pressure than control practices (test 15.1 mm Hg v control 11.3 mm Hg) and more sustained control of hypertension (test 323 days per patient-year with a diastolic pressure of 90 mm Hg or less v control 259 days).