A case of western equine encephalitis--Alberta.
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Alberta↗
Biomedical subjects
D Horne
Publications and source records attributed to D Horne.
Varicocele as the presenting sign of an abdominal mass.
A patient with a varicocele on the right side as the presenting sign of intra-abdominal Burkitt's lymphoma is reported. The incidence and etiology of varicocele are discussed.
Aged↗
Breast arteritis in polymyalgia rheumatica.
A 79-year-old woman with the clinical presentation of polymyalgia rheumatica (PMR) also had breast cancer. Histopathologic evidence of arteritis was found in mastectomy tissue and in a temporal artery, neither of which had produced symptoms before surgery. Previously reported cases are reviewed in the context that breast vasculitis may be more common than in generally recognized in patients with PMR.
Aged↗
Development of an imaging flow cytometer.
A cell analyzer that combines the characteristics of image cytometry and flow cytometry is being designed and constructed at the University of Sydney. This paper describes the image acquisition and processing components and some preliminary applications. Cells stained by a fluorescent dye and suspended in a liquid medium are conveyed by a hydraulic system to a flow channel assembly, where they are detected and illuminated by a laser beam. A two-dimensional charge-coupled device is used to acquire the cell images. Image processing and classification is to be carried out by a special-purpose computer comprising an array of four conventional microprocessors and a highly parallel processor consisting of an array of 32 X 32 processing elements. The analyzer will be capable of using morphologic, immunologic and biochemical information to classify and sort up to 500 cells per second. Because of its unique characteristics, the instrument will be of particular use in tumor heterogeneity studies.
Flow Cytometry↗
Cecal dilatation and volvulus in dairy cows: 84 cases (1977-1983).
The records of 84 cows with cecal dilatation or cecal volvulus were reviewed. The diagnosis was made by exploratory laparotomy or necropsy in 21 cows with cecal dilatation, and in 45 cows with cecal volvulus. Eighteen of the cows with cecal dilatation responded to medical management and the diagnosis was made by physical examination alone. The most useful criteria for determining that surgery was necessary were the presence of a high heart rate, apparent abdominal pain, scant or absence of feces, and the apex of the cecum rotated cranially on rectal examination. The prognosis for cattle with cecal dilatation and volvulus was good following medical therapy or decompression at surgery unless there was severe vascular compromise of the cecum. There was a 10% recurrence rate, and in these cows a partial typhlectomy was performed.
Animals↗
The personality of hand surgeons.
The aim of the present study was to investigate some aspects of motivation to practise hand surgery, psychological mindedness and personality characteristics in a group of 212 Hand Surgeons. The data was obtained by administering the Eysenck Personality Inventory, an especially constructed questionnaire, in a group setting at two conferences in Australia.
Adult↗
Competence-specific autolysis in Streptococcus sanguis.
Streptococcus sanguis strain Wicky activated to competence for genetic transformation is known to undergo a rapid decrease in optical density upon transfer to an alkaline buffer containing reducing agents. We studied the mechanism of this autolysis-like process and made the following observations. The process was specific because preincubation of the competence inducing factor with a specific inactivating protein prevented both cellular lysis and acquisition of competence for genetic transformation. The optical density decrease of competent bacteria involved the release of a large fraction of intracellular protein, RNA and lipid. However, no hydrolysis of phospholipid and no degradation of cell wall polymers including peptidoglycan could be detected. No peptidoglycan hydrolase activity capable of degrading radiolabelled S. sanguis cell walls was detected in unfractionated S. sanguis extracts. It is suggested that autolysis of competent S. sanguis involves the activity of a novel type of murein hydrolase that introduces only a limited number of bond breaks into the peptidoglycan.
Autolysis↗
Pneumococcal Forssman antigen: enrichment in mesosomal membranes and specific binding to the autolytic enzyme of Streptococcus pneumoniae.
The choline-containing pneumococcal membrane teichoic acid (Forssman antigen) can be isolated with the membrane fractions of the bacteria. The small vesicle (mesosomal) fraction generated during the formation of protoplasts seems to be highly enriched in this material. Forssman antigen was identified in cell fractions on the basis of (i) radioactive choline label, (ii) autolysin-inhibitory activity, and (iii) the sedimentation profile in sucrose density gradients with and without detergent. A membrane teichoic acid could also be isolated from pneumococci grown in medium in which choline was replaced by ethanolamine as the nutritionally required amino alcohol. This material contained radioactive ethanolamine label and behaved similarly to the choline-containing membrane teichoic acid during centrifugation in detergent-containing and detergent-free density gradients. On the other hand, the material had only low autolysin-inhibitory activity. Binding of pure pneumococcal autolysin to micelles of purified Forssman antigen could be demonstrated by mixing these components in vitro and analyzing them by sucrose density gradients and by agarose chromatography. No binding could be observed between the pneumococcal enzyme and the micellar forms of either cardiolipin or polyglycerophosphate-type lipoteichoic acid isolated from Streptococcus lactis.
Amidohydrolases↗
Factors affecting sensitivity of group B streptococci to an exogenous murein hydrolase.
Group B streptococci treated with cell wall synthesis inhibitors (penicillin or vancomycin) or by a variety of membrane-acting agents are sensitized to the lytic action of exogenous M1 muramidase. Muramidase without a sensitizing agent caused rupture of bacterial chains only, accompanied by the release of a small amount of cell wall peptidoglycan label and an increase of the number of colony-forming units. In combination with sensitizing agents the exogenous muramidase appeared to initiate hydrolysis of biosynthetically new peptidoglycan. Treatment of the cells with chloramphenicol or starvation for nutritionally required amino acids suppressed the rate of cell lysis and peptidoglycan hydrolysis during subsequent sensitization and muramidase treatment of the bacteria. Purified cell walls prepared from the amino acid starved cells were also hydrolyzed with a slower rate by muramidase. It is suggested that agents sensitizing the bacteria to the exogenous muramidase act by perturbing or removing some nonmurein components of the cell envelope which protect the peptidoglycan from the activity of exogenous enzyme. Agents increasing resistance against exogenous muramidase may also cause some alteration in peptidoglycan structure.
Cell Division↗
Privatisation in the care of the elderly.
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Aged↗
Treatment of six cases of mesothelioma with doxorubicin and cisplatin.
Six patients with unresectable malignant mesothelioma were treated with chemotherapy consisting of doxorubicin and cisplatin every 3 weeks. One patient with paratesticular mesothelioma metastatic to lungs entered complete remission for 8 months; his disease has relapsed but he is alive 32 months after initiation of chemotherapy. One patient with peritoneal mesothelioma achieved partial response for 12 months. Two patients with pleural mesothelioma achieved a partial response of 5- and 6-month durations, respectively. Two patients with pleural mesothelioma failed to respond to this regimen. Thus, four of six patients responded to doxorubicin-cisplatin chemotherapy. These preliminary results merit further study and confirmation; future investigations of cisplatin alone are necessary to better define the role of this agent in mesothelioma.
Adult↗
Hypersusceptibility of penicillin-treated group B streptococci to bactericidal activity of human polymorphonuclear leukocytes.
Pretreatment of serotype Ib group B streptococci with benzylpenicillin, other beta-lactam antibiotics, or vancomycin increased the susceptibility of these bacteria to the bactericidal activity of a mixture of human polymorphonuclear leukocytes and normal human serum. Increased susceptibility of the bacteria to killing by phagocytes was elicited even by exposure to subinhibitory levels of the beta-lactam antibiotics. Inhibitors of protein synthesis did not induce such susceptibility. We investigated the possible biochemical basis of penicillin-induced susceptibility to phagocytosis. Penicillin treatment induced the release of substantial quantities of group B streptococcal surface components into the growth medium (lipoteichoic acid, lipid, and capsular polysaccharide). Labeling of the live streptococci with 3H-labeled penicillin was used to evaluate the effect of exposure to subinhibitory concentrations of this antibiotic on the penicillin-binding proteins. Our results suggested that beta-lactam antibiotics and components of the immune system may act in concert to eliminate invading bacteria.
Adult↗
pH-dependent penicillin tolerance of group B streptococci.
Group B streptococci lose viability without apparent lysis during treatment with beta-lactam antibiotics and vancomycin. Rapid loss of viability was observed in early-exponential-phase cultures. Cultures in the mid-exponential growth phase exhibited various degrees of resistance to the bactericidal effect of the antibiotics, whereas their susceptibilities to the growth-inhibitory effect remained unchanged. This growth-phase-dependent tolerance was caused by the gradual increase in acidity of the cultures as the cell concentration increased. Retitration of the pH to neutrality made the formerly tolerant bacteria again fully susceptible to the killing effect of penicillin. Conversely, lowering the pH value of the medium resulted in antibiotic tolerance throughout culture growth. The penicillin-binding proteins of whole bacteria and their labeling pattern were found to be independent of culture pH. It is suggested that the mechanism of Ph-dependent tolerance is indirect and may be mediated by an autolysin. The tolerance of group B streptococci for penicillin could be clinically relevant in view of the relatively low pH values known to prevail in the natural host environments colonized by these bacteria.
Adult↗
Lethal effect of a heterologous murein hydrolase on penicillin-treated Streptococcus sanguis.
Nine strains of Streptococcus sanguis exhibited tolerance to benzylpenicillin: the growth of each strain was susceptible to penicillin with minimal inhibitory concentrations of 0.1 mug/ml or lower, but the bacteriolytic and bactericidal effects were limited in each case. The tolerance of these bacteria was also reflected in the large discrepancies between the minimal inhibitory and minimal bactericidal concentrations for benzylpenicillin. The hypothesis that a natural deficiency of endogenous murein hydrolase (autolysin) in this species accounts for the penicillin tolerance was tested by using a heterologous murein hydrolase, the C-phage-associated lysin. In seven of the strains, addition of the lysin to the culture together with penicillin or other cell wall inhibitors resulted in lysis and rapid loss of viability. The enzyme alone did not appreciably affect normally growing cultures. The irreversible effects of penicillin plus lysin were drastically reduced in the presence of the bacteriostatic agents chloramphenicol and cerulenin. Speculations based on experiments are presented for the mechanisms by which penicillin treatment sensitizes these bacteria to an exogenous lytic enzyme. Similar phenomena requiring cooperation of host factors and penicillin may occur during infection, since somewhat similar although less pronounced results were obtained by addition of human lysozyme to penicillin-treated S. sanguis.
Amidohydrolases↗
Man is a social animal.
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Attitude to Health↗
Release of lipoteichoic acid from Streptococcus sanguis: stimulation of release during penicillin treatment.
The spontaneous and the penicillin-stimulated release of water-soluble, glycerol-labeled polymers was compared in Streptococcus sanguis. In contrast to the spontaneous release occurring in exponentially growing or stationary-phase bacteria, penicillin-treated cells released the bulk of these polymers, and they were not replenished by synthesis during antibiotic treatment. Furthermore, a major portion of the extracellular polymers was characterized as acylated lipoteichoic acid.
Erythrocytes↗
Tolerant response of Streptococcus sanguis to beta-lactams and other cell wall inhibitors.
In contrast to group A streptococci or Streptococcus pneumoniae, cells of Streptococcus sanguis (group H) do not exhibit the irreversible effects of penicillin treatment, such as loss of viability or lysis. On the other hand, the same bacteria show typical effects of penicillin, such as morphological alterations, reduction in the rate of cell wall synthesis, and secretion of murein and lipoteichoic acid polymers into the medium. A novel effect of cell wall inhibitors was also noted: treatment with beta-lactams or with fosfomycin, d-cycloserine, or beta-halogeno-d-alanine caused the release of substantial amounts of glycerol lipids into the growth medium. The antibiotic "tolerance" of S. sanguis is interpreted in terms of the hypothesis that the activity of bacterial murein hydrolases is essential for the irreversible effects of cell wall inhibitors.
Alanine↗
Secretion of lipids induced by inhibition of peptidoglycan synthesis in streptococci.
Inhibition of peptidoglycan synthesis causes an immediate and massive secretion of both newly synthesized and "old" lipids from several species of bacteria, including streptococci, Staphylococcus epidermidis, and Bacillus subtilis. Lipid secretion occurs in the absence of detectable bacterial lysis. This novel phenomenon was examined in more detail in three strains of streptococci: S. sanguis (group H), S. pyogenes (group A), And S. pneumoniae. The secretion of lipids is specifically induced by inhibitors of peptidoglycan synthesis; it is not caused by inhibitors of protein, ribonucleic acid, or deoxyribonucleic acid synthesis. The occurrence appears to be reversible since penicillin-induced secretion comes to a halt upon the timely addition of penicillinase, correlating with resumption of culture growth. All cellular lipids are secreted in essentially the same proportions as those found in the drug treated bacteria. It is suggested that continued peptidoglycan synthesis may be essential for the integration and retention of lipid material in the plasma membrane.
Alanine↗