Testicular compensatory hypertrophy in the hemicastrated calf: effects of exogenous estradiol

Unilaterally orchidectomized (hemicastrated) bull calves were studied to monitor possible changes in serum concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) during the phase of testicular compensatory growth, to examine the characteristics of LH and FSH binding to the testis of the post-pubertal animal, and to determine whether any of these responses were altered by exogenous estradiol. Twenty-four calves were assigned randomly at one week of age to a 2 X 2 factorial experiment involving intact control (I) and hemicastrated animals (H), as well as estradiol-implanted intact (I+E2) and hemicastrated animals (H+E2). Relative to I, testis growth was accelerated in H and suppressed in I+E2 and H+E2. Mean testis weights at 27 weeks of age were 42 +/- 4, 72 +/- 6, 12 +/- 1 and 14 +/- 1 g for the four respective treatment groups. Serum FSH, but not serum LH, was positively associated with the accelerated testis growth of H. LH and FSH binding per testis were both enhanced approximately twofold in the testis from hemicastrated animals relative to those from intact calves. In contrast, estradiol markedly suppressed the number of LH-binding sites per testis in both I and H calves, but only suppressed the number of FSH-binding sites per testis in H calves. LH-affinity constants were not affected by treatment, whereas those for FSH were significantly decreased by estradiol. In conclusion, neonatal hemicastration results in elevated serum FSH, testicular compensatory hypertrophy, and an increased number of gonadotropin receptors in the bovine testis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Differences in mortality from acute myocardial infarction between coronary care unit and medical ward: treatment or bias?

To analyse the effectiveness of coronary care units in reducing mortality from myocardial infarction 18 hospitals ranging from large urban teaching hospitals to small country hospitals were stratified into four levels of care. Previous analysis had failed to show significant differences in the overall mortality in hospital among levels. There were significant differences in mortality, however, between those patients allocated to be cared for in the coronary care unit and those in the medical wards in the more advanced hospitals. The differences were largest in the hospitals with the most elaborate facilities (level 1) and non-existent in those with the least (level 4). Several analytical approaches to these observed differences indicated that they were: (a) reduced by adjustment for age and severity of infarction; (b) paralleled by differences in coexisting disease recorded on death certificates; (c) no longer significant at level 1 after allowing for differences in coexisting disease; and (d) not significant at any level after exclusion of patients first diagnosed at necropsy. These findings suggest that the observed differences in mortality between coronary care units and medical wards are largely due to bias in selection and diagnosis.     

Response of microbial adhesives and biofilm matrix polymers to chemical treatments as determined by interference reflection microscopy and light section microscopy.

The polymers involved in the adhesion of Pseudomonas fluorescens H2S to solid surfaces were investigated to determine whether differences between cell surface adhesives and biofilm matrix polymers could be detected. Two optical techniques, i.e., interference reflection microscopy (IRM) and light section microscopy (LSM), were used to compare the responses of the two types of polymer to treatment with electrolytes, dimethyl sulfoxide (DMSO), and Tween 20. To evaluate initial adhesive polymers, P. fluorescens H2S cells were allowed to attach to glass cover slip surfaces and were immediately examined with IRM, and their response to chemical solutions was tested. With IRM, changes in cell-substratum separation distance between 0 and ca. 100 nm are detectable as changes in relative light intensity of the image; a contraction of the polymer would be detected as a darkening of the image, whereas expansion would appear as image brightening. To evaluate the intercellular polymer matrix in biofilms, 3-day-old biofilms were exposed to similar solutions, and the resultant change in biofilm thickness was measured with LSM, which measures film thicknesses between 10 and 1,000 microns. The initial adhesive and biofilm polymers were similar in that both appeared to contract when treated with electrolytes and to expand when treated with Tween 20. However, with DMSO treatment, the initial adhesive polymer appeared to contract, whereas there was no change in thickness of the biofilm polymer. These results indicate that both polymers bear acidic groups and thus act electrostatically with cations and are able to enter into hydrophobic interactions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bacterial desorption from food container and food processing surfaces

The desorption ofStaphylococcus aureus, Acinetobacter calcoaceticus, and a coryneform from the surfaces of materials used for manufacturing food containers (glass, tin plate, and polypropylene) or postprocess canning factory conveyor belts (stainless steel and nylon) was investigated. The effect of time, pH, temperature, and adsorbed organic layers on desorption was studied.S. aureus did not detach from the substrata at any pH investigated (between pH 5 and 9).A. calcoaceticus and the coryneform in some cases detached, depending upon pH and substratum composition. The degree of bacterial detachment from the substrata was not related to bacterial respiration at experimental pH values. Bacterial desorption was not affected by temperature (4–30°C) nor by an adsorbed layer of peptone and yeast extract on the substrata. The results indicate that bacterial desorption, hence bacterial removal during cleaning or their transfer via liquids flowing over colonized surfaces, is likely to vary with the surface composition and the bacterial species colonizing the surfaces.     

The influence of increasing chlorine content on the accumulation and metabolism of polychlorinated biphenyls (PCBs) by Paul's Scarlet Rose cells

Four radiolabled congeners of biphenyls with increasing chlorine content (biphenyl; 1-monochlorobiphenyl; 2,2,4,4-tetrachlorobiphenyl; and 2,2,4,4,5,5-hexachlorobiphenyl) were provided to suspension cultures of rose (Rosa sp. cv. Paul's Scarlet) for 4 days. Both the kinetics of ¹⁴C exchange between the cells and medium, and the metabolism of the parent compounds depended on the chlorine content of the congeners. Analysis of both the cells and their medium showed that of the recovered radioactivity 88%, 86%, and 3% of the biphenyl, 1-PCB, and 2,2,4,4-PCB were metabolized respectively to polar and insoluble residue products. The 2,2,4,4,5,5-PCB did not appear to be metabolized.     

Evidence that the requirements for ATP and wheat germ initiation factors 4A and 4F are affected by a region of satellite tobacco necrosis virus RNA that is 3' to the ribosomal binding site

A cDNA containing the complete genome of satellite tobacco necrosis virus (STNV) RNA was constructed and cloned into a plasmid vector containing the T7 polymerase promotor. A second clone containing the first 54 nucleotides from the 5' end, which includes the ribosome binding site, was also constructed. RNAs were transcribed from these plasmids (pSTNV1239 and pSTNV54) and tested for their ability to bind to wheat germ 40 S ribosomal subunits in the presence of wheat germ initiation factors eIF-4A, eIF-4F, eIF-4G, eIF-3, eIF-2, Met-tRNA, ATP, and guanosine 5'-(beta, gamma-imino)triphosphate (GMP-PNP). Maximal binding of the STNV RNA transcribed from pSTNV1239 is obtained only in the presence of all the initiation factors and ATP. In contrast, close to maximal binding of STNV RNA transcribed from pSTNV54 is obtained in the absence of eIF-4A, eIF-4F, eIF-4G, and ATP. A series of deletion clones from the 3' end of the STNV cDNA was prepared, and the requirements for binding to 40 S ribosomal subunits were determined. STNV RNAs containing more than 134 nucleotides from the 5' end require eIF-4A, eIF-4F, eIF-4G, and ATP for maximal binding to 40 S ribosomal subunits, whereas STNV RNAs containing 86 nucleotides or less no longer require ATP and these factors. These findings indicate that a region 3' to the initiation codon affects the requirements for eIF-4A, eIF-4F, eIF-4G, and ATP.     

Schistosoma mansoni: chemotherapy of infections of different ages

Mice were treated with potassium antimony tartrate, hycanthone, oxamniquine, niridazole, or praziquantel at different times after infection with Schistosoma mansoni. The rate of cure was assessed by perfusion of surviving worms approximately 4 weeks after treatment, and the percentage reduction in worm burden was estimated relative to the number of adult worms perfused from control mice, comparably infected but untreated. All six drugs were relatively inactive against S. mansoni between 3 and 4 weeks after infection when compared with treatment at 5 to 6 weeks. However, the drugs differed in the patterns of cure they achieved in the 2-week period after administration of cercariae and in the period around the onset of patency. Worms that had been subjected to amoscanate or hycanthone in the third week after infection showed evidence of this as adults in having a reduced fecundity. Factors such as worm or host physiology, or host immune status may have had roles in the outcome of chemotherapy at different stages of maturation of S. mansoni.     

Influence of partial defoliation of green pepper on the senescence,growth, and nitrate reductase of the remaining leaf

Summary Removal of all but one leaf from pepper plants prevented the senescence of the remaining leaf and caused increases of approximately 140, 200, and 200%, respectively in leaf area, weight, and nitrate reductase activity. Development of the fruit (fresh and dry weight increases) was only approximately 65% of that of fruit on control plants.     

Diacylglycerol lipase and kinase activities in rat brain microvessels

Diacylglycerols can accumulate transiently in intact cells as a consequence of the degradation of phosphatidylinositol by phospholipase C, but little information is available concerning their metabolic fate in the vascular endothelium. Diacylglycerol lipase and kinase activities were measured in rat brain microvessel preparations. Lipase activity, measured by the release of free fatty acids, was much greater at pH 4.5 than at pH 7. The acid lipase was predominantly particulate and likely originated in lysosomes, whereas the neutral lipase was mainly soluble. The fatty acid at the sn-1 position of the diacylglycerol substrate was hydrolyzed faster than that at the sn-2 position at both pH 4.5 and 7. The 2-monoacylglycerol accumulated at pH 4.5 but not at 7 due to the presence of a monoacylglycerol lipase activity with a neutral pH optimum. The formation of phosphatidic acid (kinase activity) was also measured in microvessels. When lipase and kinase activities were measured simultaneously, the formation of phosphatidic acid from a 1-palmitoyl-2-[1-14C]oleoyl-sn-glycerol substrate was 4-fold greater than the release of fatty acid (oleate) from the sn-2 position. Introduction of arachidonic acid to the sn-2 position of the diacylglycerol substrate increased kinase activity but reduced lipase activity. The release of fatty acids from the sn-2 position of phosphatidic acid could not be detected.     

Synergistic effects of cyclic AMP and nerve growth factor on neurite outgrowth and microtubule stability of PC12 cells

The outgrowth of neurites from rat PC12 cells stimulated by combined treatment of nerve growth factor (NGF) with cAMP is significantly more rapid and extensive than the outgrowth induced by either factor alone. We have compared the responses of PC12 cells under three different growth conditions, NGF alone, cAMP alone, and combined treatment, with respect to surface morphology, rapidity of neurite outgrowth, and stability of neurite microtubules, to understand the synergistic action of NGF and cAMP on PC12. Surface events at early times in these growth conditions varied, suggesting divergent pathways of action of NGF and cAMP. This suggestion is strongly supported by the finding that cells exposed to saturating levels of dibutyryl cAMP without substantial neurite outgrowth initiated neurites within 5 min of NGF. This response has been adopted as a convenient assay for NGF. Neurites that regenerated in the three growth conditions showed marked differences in stability to treatments that depolymerize microtubules. The results indicate that microtubules in cells treated with both NGF and cAMP are significantly more stable than in either growth factor alone. We suggest that a shift of the assembly equilibrium favoring tubulin assembly is a necessary prerequisite for the initiation of neurites by PC12.