Chlamydia trachomatis in Canada: an update.
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Adolescent↗
Biomedical subjects
J Doherty
Publications and source records attributed to J Doherty.
Trends in gonorrhea in Canada, 1990-1995.
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Adolescent↗
Polyomavirus large T antigen overcomes p53 dependent growth arrest.
Polyomavirus transforms cells in culture and induces tumors in mice without apparent interaction with or inactivation of the p53 tumor suppressor protein. In this report we investigate the ability of polyomavirus T antigens to overcome the growth suppression function of p53. A temperature sensitive p53 gene was introduced into mouse embryo fibroblasts derived from a p53 null mouse, resulting in expression of a protein with a mutant conformation at 37 degrees C and a functionally wild-type conformation at 32 degrees C. We found that expression of p53 at 32 degrees C induced the cyclin-dependent kinase inhibitor p21/WAF1 and arrested cell growth in the G1/G0 phase of the cell cycle. Only the under-phosphorylated form of the retinoblastoma tumor suppressor protein (pRB) was detected in these growth arrested cells. We introduced both polyomavirus large T (LT) and middle T (MT) antigens into this cell line and showed that LT overcame p53-dependent growth arrest, while MT did not. In cells grown at 32 degrees C, LT expession led to cell proliferation and phosphorylation of pRB in the presence of p21. A mutant LT containing a defective pRB binding domain failed to overcome the growth arrest, indicating that interaction of LT with RB proteins is required to override p53 function. Although the polyomavirus T antigens do not interact with p53 directly, our results indicate that the virus, through LT, is able to interfere with the growth suppressive activity of p53.
Animals↗
Is circulating endotoxin the trigger for the systemic inflammatory response syndrome seen after injury?
OBJECTIVE: Patients with severe traumatic or burn injury and a mouse model of burn injury were studied early after injury to determine the relation of plasma endotoxin (lipopolysaccharide [LPS]) to the production of proinflammatory cytokines and subsequent resistance to infection. SUMMARY BACKGROUND DATA: Elevated levels of plasma LPS have been reported in patients after serious injury. It has been suggested that circulating LPS may be a trigger for increased proinflammatory cytokine production and may play a role in the septic syndromes seen in a substantial portion of such patients. Yet, despite multiple reports of leakage of LPS from the gut and bacterial translocation after injury in animal models, there is little direct evidence linking circulating LPS with production of inflammatory mediators. METHODS: The authors studied serial samples of peripheral blood from 10 patients with 25% to 50% surface area burns and 8 trauma patients (injury Severity Score, 25-57). Patients were compared with 18 healthy volunteers. The study was focused on the first 10 days after injury before the onset of sepsis or the systemic inflammatory response syndrome. Plasma samples were assayed for LPS, and adherent cells from the blood were studied for basal and LPS-stimulated production of tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and interleukin-6 (IL-6). The correlation of increased plasma LPS with TNF-alpha production was studied as was the association of increased plasma LPS and increased TNF-alpha production with subsequent septic complications. We also studied a mouse model of 25% burn injury. Burn mice were compared with sham burn control subjects. Plasma samples were assayed at serial intervals for LPS, and adherent cells from the spleens were studied for basal- and LPS-stimulated production of TNF-alpha, IL-1 beta, and IL-6. Expression of the messenger RNAs for IL-1 beta and TNF-alpha also was measured. The relation of increased TNF-alpha production with mortality from a septic challenge, cecal ligation and puncture (CLP), was determined. Finally, the effect of administration of LPS to normal mice on subsequent mortality after CLP and on TNF-alpha production was studied. RESULTS: Elevated plasma LPS (> 1 pg/mL) was seen in 11 of the 18 patients within 10 days of injury and in no normal control subjects. In this period, patients as compared with control subjects showed increased stimulated production of TNF-alpha, IL-1 beta, and IL-6. Increased TNF-alpha production was not correlated with elevated plasma LPS in the same patients. Neither increased plasma LPS nor increased TNF-alpha production early after injury was correlated with subsequent development of systemic inflammatory response syndrome or sepsis in the patients. Burn mice, as compared with sham burn control subjects, showed elevated plasma LPS levels chiefly in the first 3 days after injury. Increased stimulated production of proinflammatory cytokines by adherent splenocytes from the burn mice also was seen at multiple intervals after injury and did not correlate with mortality from CLP. Increased production of TNF-alpha and IL-1 beta was associated with increased expression of messenger RNAs for these cytokines. Finally, two doses of 1 ng LPS administered 24 hours apart to normal mice had no effect on mortality from CLP performed 7 days later nor on the production of TNF-alpha at the time of CLP. CONCLUSIONS: These findings call into question the idea that circulating LPS is the trigger for increased proinflammatory cytokine production, systemic inflammatory response syndrome, and septic complications in injured patients.
Animals↗
Regulation of excitatory input to inhibitory interneurons of the dentate gyrus during hypoxia.
The role of metabotropic glutamate receptors (mGluRs) and adenosine receptors in hypoxia-induced suppression of excitatory synaptic input to interneurons residing at the granule cell-hilus border in the dentate gyrus was investigated with the use of whole cell electrophysiological recording techniques in thin (250 microns) slices of immature rat hippocampus. Minimal stimulation evoked glutamatergic excitatory postsynaptic currents (EPSCs) in dentate interneurons in 68 +/- 4% (mean +/- SE) of trials during stimulation in the dentate granule cell layer (GCL) and 48 +/- 3% of trials during stimulation in CA3. Hypoxic episodes, produced by switching the perfusing solution from 95% O2-5% CO2 to a solution containing 95% N2-5% CO2 for 3-5 min, rapidly and reversibly decreased the synaptic reliability, or probability of evoking an EPSC, from either input without reducing EPSC amplitude, consistent with a presynaptic suppression of transmitter release. The mGluR antagonist (+)-alpha-methyl-4-carboxyphenylglycine [(+) MCPG; 500 microM] did not alter synaptic reliability or mean EPSC amplitude in either pathway. However, (+) MCPG significantly attenuated hypoxic suppression of input from both pathways, suggesting that mGluRs activated by release of glutamate partially mediate hypoxic suppression of EPSCs to dentate interneurons. The mGluR agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD; 100 microM) rapidly decreased the reliability of excitatory transmission from both the GCL (19 +/- 5% of control) and CA3 (39 +/- 15% of control). ACPD also increased the frequency of spontaneous EPSCs and evoked a slow inward current in dentate interneurons. Exogenous adenosine (10-300 microM) decreased synaptic reliability for both pathways and reduced the frequency of spontaneous EPSCs, but did not cause a decrease in the mean amplitude of evoked EPSCs, consistent with a presynaptic suppression of excitatory input to dentate interneurons. Conversely, the selective adenosine A1 receptor antagonists 8-cyclopentyl-1,3-dipropylxanthine (200 nM to 1 microM) and N6-cyclopentyl-9-methyladenine (1 microM) enhanced excitatory input to dentate interneurons by increasing synaptic reliability for both the GCL and CA3 inputs. Adenosine A1 receptor antagonists did not, however, reduce hypoxic suppression of excitatory input to dentate interneurons. These results indicate that hypoxia induces a presynaptic inhibition of excitatory input to dentate interneurons mediated in part by activation of mGluRs, but not adenosine A1 receptors, whereas both mGluRs and adenosine A1 receptors can depress excitatory input to dentate interneurons during normoxic stimulation. Regulation of excitatory input to dentate interneurons provides a mechanism to shape excitatory input to the hippocampus under both normal and pathological conditions.
Animals↗
Value for money in South African health care: findings of a review of health expenditure and finance.
This article highlights the most striking findings of a review of health expenditure and finance in South Africa in 1992/3. The level of national expenditure on health care, and the distribution of resources between the public and private sectors, are discussed first. Then the article highlights the maldistribution of financial, physical and human resources on a geographic basis, racially and between levels of care. The cost of redressing inequities, at least at the primary care level, is mentioned in the context of seeking options for additional sources of finance. The article concludes by examining the planning prerequisites for successful reform.
Financial Support↗
Hereditary deficiency of the seventh component of complement and recurrent meningococcal infection: investigations of an Irish family using a novel haemolytic screening assay for complement activity and C7 M/N allotyping.
Terminal complement component deficiency predisposes to meningococcal infection and is inherited in an autosomal co-dominant manner. An Irish family is described, in which 2 of 3 brothers had recurrent meningococcal infection. A novel screening assay was used to investigate for terminal complement deficiency and the 2 affected brothers were found to be completely deficient in the seventh component of complement (C7). Enzyme-linked immunosorbent assay for C7 revealed lower than normal levels in the remaining brother and parents. C7 M/N protein polymorphism allotyping, used to investigate the segregation of the C7 deficiency genes, showed that the apparently complement sufficient brother was heterozygous C7 deficient and a carrier of one of the deficiency genes. Complement screening should be carried out in any individual suffering recurrent meningococcal infection or infection with an uncommon meningococcal serogroup. Identification of complement deficient patients allows the implementation of strategies to prevent recurrent infection.
Adolescent↗
Microtympanometry, microscopy and tympanometry in evaluating middle ear effusion prior to myringotomy.
OBJECTIVE: To determine the accuracy of a hand-held microtympanometer (Microtymp, Welch Allyn) used by a general practitioner when compared with findings at myringotomy. METHOD: Independent preoperative assessment of children's ears using microtympanometry by a general practitioner, microscopy and pneumatic otoscopy by a specialist otologist and impedance bridge tympanometry by a specialist audiologist were performed and compared with findings at myringotomy. SUBJECTS: Fifty children (100 ears) on the waiting list for bilateral myringotomies and ventilation tube insertion for recurrent acute otitis media or otitis media with effusion. RESULTS: Microscopy with pneumatic otoscopy had a 90.9% sensitivity and a 92.9% specificity in detecting middle ear effusions. Impedance bridge tympanometry had a 94.4% sensitivity and a 71.8% specificity if type B and C2 were combined to predict middle ear effusion. Microtympanometry had 100% sensitivity and 75% specificity if type B and C tympanograms were combined; if type B tympanograms alone were used, a sensitivity of 83.4% and specificity of 75% in predicting middle ear effusions was obtained. CONCLUSION: The Microtypm is a useful instrument in general practice for assessment of middle ear effusions as no ears with fluid were missed in this study if type B and C tympanograms were considered abnormal. The Microtymp would also be useful as a screening instrument by suitably trained personnel.
Acoustic Impedance Tests↗
Control of falciparum malaria.
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Animals↗
Binding of the cytosolic p200 protein to Golgi membranes is regulated by heterotrimeric G proteins.
The formation of vesicles for protein trafficking requires the dynamic binding of cytosolic coat proteins onto Golgi membranes and this binding is regulated by a variety of GTPases, including heterotrimeric G proteins. We have previously shown the presence of the pertussis toxin-sensitive G alpha i-3 protein on Golgi membranes and demonstrated a functional role for G alpha i-3 in the trafficking of secretory proteins through the Golgi complex. We have also described a brefeldin A-sensitive phosphoprotein, p200, which is found in the cytoplasm and on Golgi membranes. The present study investigates the role of heterotrimeric G proteins in the regulation of p200 binding to Golgi membranes. An in vitro binding assay was used to measure the binding of cytosolic p200 to LLC-PK1 cell microsomal membranes and to purified rat liver Golgi membranes in the presence of specific activators of G proteins. The binding of p200 to Golgi membranes was compared to that of the coatomer protein beta-COP, for which G protein-dependent membrane binding has previously been established. Membrane binding of both p200 and beta-COP was induced maximally by activation of all G proteins in the presence of GTP gamma S. More selective activation of the heterotrimeric G proteins, with AlFn or mastoparan, also induced membrane binding of p200 and beta-COP. Pertussis toxin pretreatment of Golgi membranes, to selectively inactivate G alpha i-3, reduced the AlFn and mastoparan-induced binding of p200 to Golgi membranes, whereas no significant effect of pertussis toxin on beta-COP binding was found in this assay. The effect of pertussis toxin thus implicates G alpha i-3, as one component of a regulatory pathway, in the binding of cytosolic p200 to Golgi membranes. The effects of AlFn and pertussis toxin on p200 membrane binding were also shown in intact cells by immunofluorescence staining. AlFn treatment of cells induced translocation of p200 from the cytoplasm onto the Golgi complex, resulting in a conformational change in some Golgi membranes. The translocation of p200 was blocked by pretreatment of intact NRK cells with pertussis toxin. The data presented here support the conclusion that the binding of the p200 protein to Golgi membranes involves regulation by the pertussis toxin-sensitive heterotrimeric G proteins, specifically the G alpha i-3 protein.
Aluminum Compounds↗
Identification of a 200-kD, brefeldin-sensitive protein on Golgi membranes.
A mAb AD7, raised against canine liver Golgi membranes, recognizes a novel, 200-kD protein (p200) which is found in a wide variety of cultured cell lines. Immunofluorescence staining of cultured cells with the AD7 antibody produced intense staining of p200 in the juxtanuclear Golgi complex and more diffuse staining of p200 in the cytoplasm. The p200 protein in the Golgi complex was colocalized with other Golgi proteins, including mannosidase II and beta-COP, a coatomer protein. Localization of p200 by immunoperoxidase staining at the electron microscopic level revealed concentrations of p200 at the dilated rims of Golgi cisternae. Biochemical studies showed that p200 is a peripheral membrane protein which partitions to the aqueous phase of Triton X-114 solutions and is phosphorylated. The p200 protein is located on the cytoplasmic face of membranes, since it was accessible to trypsin digestion in microsomal preparations, and is recovered in approximately equal amounts in membrane pellets and in the cytosol of homogenized cells. Immunofluorescence staining of normal rat kidney cells exposed to the toxin brefeldin A (BFA), showed that there was very rapid redistribution of p200, which was dissociated from Golgi membranes in the presence of this drug. The effect of BFA was reversible, since upon removal of the toxin, AD7 rapidly reassociated with the Golgi complex. In the BFA-resistant cell line PtK1, BFA failed to cause redistribution of p200 from Golgi membranes. Taken together, these results indicate that the p200 Golgi membrane-associated protein has many properties in common with the coatomer protein, beta-COP.
Animals↗
The manager's role in developing standards.
Pick up any health care journal nowadays and you are bound to find at least one article on quality standards and audit. More and more professional staff of all disciplines are examining their practice and documenting standards of care which aim to promote a desired and achievable level of performance against which actual performance can be compared.
Humans↗
Private practice in academic medicine--a Trojan horse.
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Academic Medical Centers↗
PMN elastases: a comparison of the specificity of human isozymes and the enzyme from other species toward substrates and inhibitors.
The human elastases isolated from polymorphonuclear neutrophils (PMN) and purulent sputum displayed identical kinetic constants toward substrates and inhibitors. The elastases from the two sources yield identical N-terminal sequences and were recognized by antiserum prepared against human sputum elastase (HSE) isozyme-4 (I-4). The data support the proposal put forth by Twumasi and Liener (1977, J. Biol. Chem. 252, 1917-1926) that the human elastase from sputum is of PMN origin. PMN elastases from other species displayed kinetic constants toward both substrates and inhibitors significantly different from the human enzyme. Therefore, extrapolation of inhibitor profiles from these elastases to the human source should be avoided. Four groups of isozymes were resolved from HSE by FPLC. Only the most basic isozyme (I-4) was obtained as a single species. The isozymes displayed identical macroscopic kinetic constants toward several substrates and two classes of inhibitors. The similar partition ratios observed with a cephalosporin-derived inhibitor suggest that the microscopic rate constants are also identical. The data support the proposal suggested by Baugh and Travis (1976, Biochemistry 15, 836-841) that HLE isozymes differ only in carbohydrate content. Whatever the source of human PMN elastase heterogeneity, it does not result in heterogeneous catalytic properties. In addition, a new protein was identified in elastase preparations derived from human sputum. This protein displayed homology to serine proteases and properties suggesting that it is identical to azurocidin.
Amino Acid Sequence↗
The effect of acclimation temperature on enzyme activity in Drosophila melanogaster.
1. The response to thermal acclimation of five key rate-limiting enzymes of intermediary metabolism and of six degradative enzymes was measured in tissue extracts of adult Drosophila melanogaster which had been acclimated for 4 days to 15, 25 or 30 degrees C. 2. Three enzymes of intermediary metabolism (HK, alpha-GPDH and CO) showed positive thermal compensation, which is the type of response characteristic of the enzymes involved in energy metabolism in vertebrate ectotherms. 3. The data obtained for CS and G6PDH showed no evidence for increased activity of TCA cycle nor of the pentose phosphate pathway upon cold acclimation in D. melanogaster. 4. Two degradative enzymes, ADH and non-specific esterase, showed inverse thermal compensation which is the type of response characteristic of degradative enzymes in vertebrate ectotherms. 5. In contrast to the situation in vertebrate ectotherms, catalase and the three lysosomal enzymes assayed (APH, acid DNase and acid RNase) displayed positive rather than inverse compensation. 6. The results presented here extend the data on the range of D. melanogaster enzymes which show compensation upon thermal acclimation and on the type of acclimation response which occurs.
Acclimatization↗
Development and characterization of a rapid-onset rodent inhalation model of asbestosis for disease prevention.
A short-term inhalation model of asbestosis was developed in rodents to examine possible preventive approaches to lung disease. Fischer 344 (F344) rats were exposed for 10 and 20 days to National Institute of Environmental Health Sciences (NIEHS) crocidolite asbestos while sham controls were exposed to air only. To determine quantitative biochemical indicators of asbestos-induced lung disease, bronchoalveolar lavage (BAL) fluids were analyzed for lactic dehydrogenase (LDH), alkaline phosphatase, angiotensin-converting enzyme (ACE), and protein. Total and differential cell counts were performed on cell pellets from BAL. Lungs from additional rats were processed for histopathology, measurement of hydroxyproline, and autoradiography after injection of rats with 3H-thymidine. Exposure to asbestos for 10 and 20 days caused increases in LDH, alkaline phosphatase, and protein in BAL. In contrast, ACE was undetectable in BAL fluids from sham or asbestos-exposed rats. At both time periods, the percentages of polymorphonuclear leukocytes (PMNs) and lymphocytes in BAL were increased in asbestos-exposed rats. Total cell numbers in BAL were increased significantly at 20 days in animals inhaling asbestos. Exposure to asbestos for 10 and 20 days caused elevated amounts of hydroxyproline in lung and the development of fibrotic lesions. Asbestos-exposed rats exhibited increased numbers of interstitial cells and airspace epithelial cells incorporating 3H-thymidine, whereas labeled bronchiolar epithelial cells were not elevated significantly. The quantitative changes in asbestos-associated enzyme levels, cell types and protein in BAL, as well as increases in hydroxyproline and morphologic evidence of fibrosis, are useful indices of asbestos-related lung injury which enable preventive and therapeutic approaches to disease.
Administration, Inhalation↗
The psychiatric discharge summary: a tool for management and audit.
The aims of this study were to review the information needs of general practitioners in relation to the discharge of mentally ill patients; to design a discharge summary that would meet these needs and evaluate its use by junior hospital staff; and to assess the usefulness of this summary for audit. The information needs of general practitioners were identified from a review of the literature and from discussions with local general practitioners. A prototype discharge summary was designed and reviewed by a panel of general practitioners, regional advisors and course organizers from the south east Thames region. It was used for all patients discharged from the acute psychiatric ward in Hither Green Hospital over a 10 month period. One copy was given to the patient to take to the general practitioner, one was posted to the general practitioner and a final copy was kept in the patient's hospital records. The senior house officers found the summary easy to complete. It reduced uncertainty about what data to provide, and helped to focus on the most critical information needed by general practitioners for continuity of care. Using a pre-coded data collection sheet, analysis of the information on the summaries was easily done. It provided a rapid audit of caseload, diagnoses, therapy, methods of admission and discharge, length of stay, risk factors and roles of all involved in future management. This information can be of use to the psychiatric team, general practitioners and hospital managers and could be the first step towards the development of shared care.
Communication↗