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Biomedical subjects

D E Green

Publications and source records attributed to D E Green.

At least 19 recordsLinked to original sources
PubMed1995

Purification and properties of the lipoate protein ligase of Escherichia coli.

Lipoate is an essential component of the 2-oxoacid dehydrogenase complexes and the glycine-cleavage system of Escherichia coli. It is attached to specific lysine residues in the lipoyl domains of the E2p (lipoate acetyltransferase) subunit of the pyruvate dehydrogenase complex by a Mg(2+)- and ATP-dependent lipoate protein ligase (LPL). LPL was purified from wild-type E. coli, where its abundance is extremely low (< 10 molecules per cell) and from a genetically amplified source. The purified enzyme is a monomeric protein (M(r) 38,000) which forms irregular clusters of needle-like crystals. It is stable at -20 degrees C, but slowly oxidizes to an inactive form containing at least one intramolecular disulphide bond at 4 degrees C. The inactive form could be re-activated by reducing agents or by an as-yet unidentified component (reactivation factor) which is resolved from LPL at the final stage of purification. The pI is 5.80, and the Km values for ATP, Mg2+ and DL-lipoate were determined. Selenolipoate and 6-thio-octanoate were alternative but poorer substrates. Lipoylation was reversibly inhibited by the 6- and 8-seleno-octanoates and 8-thio-octanoate, which reacted with the six cysteine thiol groups of LPL. LPL was inactivated by Cu2+ ions in a process that involved the formation of inter- and intra-molecular disulphide bonds. Studies with lplA mutants lacking LPL activity indicated that E. coli possesses another distinct lipoylation system, although no such activity could be detected in vitro.

Amino Acid Sequence↗
PubMed1991

Subchronic hepatotoxicity of selenomethionine ingestion in mallard ducks.

Two-year-old male mallards (Anas platyrhynchos) received a control diet (0.2 ppm Se) or diets containing 1, 2, 4, 8, 16, or 32 ppm Se as selenomethionine for 14 wk. Se accumulated readily in the liver in a dose-dependent manner, reaching a mean concentration of 29 ppm (wet weight) in the 32 ppm group. Dietary Se of 2 ppm or greater increased plasma glutathione peroxidase activity. Mortality (10%) and histopathological effects, including bile duct hyperplasia and hemosiderin pigmentation of the liver and spleen, occurred in the 32 ppm group. These histopathological effects were accompanied by lower hemoglobin concentrations (16 and 32 ppm groups) and hematocrit (32 ppm group), and elevated plasma alkaline phosphatase activity (32 ppm group) indicative of cholestatic liver injury. Other manifestations of hepatotoxicity included significant linear dose responses for hepatic oxidized glutathione (GSSG) concentrations and ratio of GSSG to reduced glutathione (GSH). Means for both of these responses differed from controls in groups receiving 8-32 ppm Se. Mean hepatic GSH and malondialdehyde (a measure of lipid peroxidation) concentrations were significantly elevated in the 16 and 32 ppm groups. Subchronic effects of selenomethionine, which occurs in vegetation, are of particular interest with respect to the health of wild aquatic birds in seleniferous locations.

Alkaline Phosphatase↗
PubMed1991

Pharyngeal volume in asymptomatic snorers compared with nonsnoring volunteers.

STUDY OBJECTIVE: to determine if asymptomatic snorers have smaller pharyngeal volumes than age- and height-matched nonsnorers. DESIGN: we recruited asymptomatic heavy snorers and nonsnorers for a study. Each snorer was matched by age (+/- 3 years) and height (+/- 2 inches) with a nonsnorer. The nonsnorers were required to be near ideal body weight. All volunteers underwent overnight polysomnography, pulmonary function testing, and magnetic resonance imaging of the pharynx while awake. The volume of the pharynx was determined by a computer with data input from a digitizing instrument. SETTING: Veterans Administration Hospital and University of Florida Teaching Hospital PARTICIPANTS: Nine volunteers were recruited for both the snorer and nonsnorer groups. Each participant was paid $50. There were no interventions. MEASUREMENTS AND RESULTS: There were no differences in sleep variables between the two groups. There was also no significant difference between pharyngeal volumes for the two groups. CONCLUSIONS: The volume of the pharynx in asymptomatic snorers is similar to the volume in age- and height-matched nonsnorers.

Adult↗
PubMed1990

Attitudes to AIDS: a comparative analysis of a new and negative stereotype.

Two propositions about attitudes, which have previously been supported with respect to the mentally ill, were examined with respect to AIDS patients. The first, that people attach a stigma to the AIDS patient, was strongly supported, and two quite independent components of the stigma were found. One of these components identified as dependence, was closely related to the attributes of typical cancer patients and coronary heart patients, while the other, identified as low moral worth, clearly distinguished the AIDS patient from the other two groups of patients. The second proposition, that attitudes to AIDS are not strongly related to age, sex and occupational background, was largely supported. However there was some evidence that males rated AIDS patients lower on moral worth than did females.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Massive tracheal necrosis complicating endotracheal intubation.

There are significant complications associated with endotracheal intubation. Massive tracheal necrosis secondary to tracheoesophageal space abscess developed in a 71-year-old man during mechanical ventilation. Elevated endotracheal tube cuff pressures, sepsis, hypotension, and other risk factors predispose to this disastrous consequence.

Abscess↗
PubMed1988

Viral strain dependent differences in experimental Argentine hemorrhagic fever (Junin virus) infection of guinea pigs.

Guinea pigs infected with low-passage Junin virus of human origin showed viral strain dependent differences in mortality, LD50, time to death, and in viral spread and distribution. Different Junin strains appeared to cause at least two broad patterns of Argentine hemorrhagic fever in guinea pigs. A number of strains of Junin virus caused a viscerotropic type of illness in which virus replicated predominantly in lymph nodes, spleen, and bone marrow. With the most severe visceral forms of Argentine hemorrhagic fever, the guinea pigs became viremic, developed necrosis of spleen, lymph nodes, and bone marrow, showed gastric hemorrhages, and all animals died within 13-15 days. Other Junin strains induced a neurological type of illness with transient viral replication in and lymphocyte depletion of spleen and lymph nodes, with no detectable viremia or viral replication in bone marrow. Subsequently, virus was found in the brain with varying severities of polioencephalitis, and the guinea pigs frequently showed rear leg paralysis before death occurred 28-34 days after inoculation. Not all animals infected with a neurotropic strain developed all these signs. One viral strain induced some signs characteristic of both patterns of illness. Although the disease forms in the guinea pig model did not strictly correlate with those observed in the humans from which these strains were obtained, the different strains of Junin virus consistently caused very different patterns of illness in infected guinea pigs.

Animals↗
PubMed1987

Virus-specific factors in experimental Argentine hemorrhagic fever in rhesus macaques.

A nonhuman primate model for Argentine hemorrhagic fever has been developed that closely mimics the human clinical syndrome. Parenteral infection of adult Macaca mulatta with low-passage isolates of two Junin viral strains resulted in distinctive hemorrhagic or neurological disease in rhesus macaques that correlated with clinical illness patterns present in the humans from whom the viral strains were obtained. Transient leukopenia, together with thrombocytopenia and secondary bacterial septicemia, were documented among animals infected with both viral strains. In contrast, differing patterns of viremia, oropharyngeal viral shedding, and antibody response occurred in the two virus-infected groups. These results, together with postmortem virologic and histopathologic findings, suggest that viral-strain-specific factors are important determinants of clinical disease patterns in this model system.

Animals↗
PubMed1987

Experimental Argentine hemorrhagic fever in rhesus macaques: virus-specific variations in pathology.

Two isolates of Junin virus (Espindola and Ledesma) inoculated into rhesus macaques produced distinct lesions which were strain-constant and similar to reported human cases of Argentine hemorrhagic fever. The Espindola isolate was associated with hemorrhagia, necrosis of bone marrow, and mild hepatocellular necrosis. Ledesma isolate was associated with pronounced polioencephalomyelitis and autonomic ganglioneuritis, but very mild or absent hepatocellular necrosis, bone marrow necrosis, and hemorrhagia. Deaths of Espindola-infected macaques were usually attributed to hemorrhagia with severe secondary bacterial infections, while in Ledesma-infected macaques, death was associated either with early severe secondary bacterial infections or slowly progressive polioencephalomyelitis. These two Junin virus isolates demonstrated hemorrhagic viscerotropism or neurotropism in macaques, suggesting that the variety of Argentine hemorrhagic fever syndromes in man may be virus-isolate determined.

Animals↗
PubMed1987

Community attitudes to mental illness in New Zealand twenty-two years on.

Three propositions about attitudes to mental illness derived from Nunnally (Popular Conceptions of Mental Health. Holt, Rinehart & Winston, New York, 1961) were examined with the semantic differential technique as it was used originally by Olmsted and Ordway (Final Report to National Institutes of Mental Health, 1963). Attitudes were compared between several studies using the same measures, that ranged over 22 years from 1962 to 1984. The results were remarkably consistent across all studies, indicating that the community had persistently negative attitudes towards the mentally ill and was no more likely today to want to play a major role in the care of the mentally ill than was the case more than 20 years ago. As a consequence it appears that there will need to be substantial and permanent attitude change, of a kind fleetingly observed over the period of the study, before the professional care of the mentally ill in the community may be expected to have maximum impact.

Attitude↗
PubMed1987

Pilomatrix carcinoma.

A pilomatrix carcinoma presented as a large ulcerated mass in the left axilla. Histologically, irregular nests of basaloid matrix cells with cystic centers containing necrotic debris and "shadow cells" were seen. The tumor invaded adjacent structures and was characterized by areas of cellular pleomorphism, crowding of cells, and numerous mitotic figures. An occasional atypical mitosis was noted. A review of 16 cases reported in the world literature is included, with emphasis on epidemiology and treatment.

Axilla↗
PubMed1987

Studies of the coagulation system in arenaviral hemorrhagic fever: experimental infection of strain 13 guinea pigs with Pichinde virus.

Significant coagulation abnormalities were associated with experimental infection of strain 13 guinea pigs with Pichinde virus, an arenavirus related to the virulent human pathogens Junin, Machupo, and Lassa viruses. Infected animals developed decreased activity of multiple coagulation factors, decreased antithrombin III levels, high levels of fibrin-fibrinogen degradation products, impaired platelet function, and thrombocytopenia. Testing for the presence of a coagulation inhibitor revealed a pattern consistent with factor deficiency. Fibrin thrombi were not found at necropsy. The findings of high fibrin-fibrinogen degradation product levels and decreased antithrombin III levels, in association with decreased activity of multiple coagulation factors and thrombocytopenia, suggest that intravascular coagulation is a feature of this experimental infection. The demonstration of abnormal platelet function is also significant, as this could contribute to defective hemostasis despite the moderate thrombocytopenia which usually occurs in arenaviral disease.

Animals↗
PubMed1986

Treatment of junin virus-infected guinea pigs with immune serum: development of late neurological disease.

Guinea pigs infected with Argentine hemorrhagic fever virus (Junin) were treated with pooled, homologous convalescent sera. Use of 15,000 or 5,000 therapeutic units of immune sera prevented all signs of illness when administered within 24 hr of infection. We could also prevent illness and death in infected guinea pigs as late as 6 days after infection if we used more antisera (30,000 therapeutic units/kg). In some treatment groups, surviving animals developed a late neurological syndrome with prominent rear-limb paralysis. Treated animals typically expressed higher viral titers in the brain than in any other organ. There appeared to be no acute exacerbation of disease by antibody administration. Our data suggest that, after replicating peripherally, Junin virus infects the brain where circulating immunoglobulins may not eliminate viable virus. Subsequent replication of virus in the brain may generate a neurological phase of the illness. Histological examination of brains from guinea pigs in treatment groups favoring the neurological phase of illness showed encephalitis, meningitis, and swollen astrocytes, suggestive of neuronal degeneration. There is likely a delicate balance among presence of virus in the brain, the amount of antibody transported into the central nervous system, and the occurrence of this late neurological aspect of experimental Argentine hemorrhagic fever. Further study of this model may elucidate factors relevant in understanding the continuing problem of the late neurological syndrome seen in some human cases of Argentine hemorrhagic fever treated with immune plasma.

Animals↗
PubMed1986

Comparative perceptions of driver ability--a confirmation and expansion.

This study aimed to investigate earlier Swedish and United States research which has shown that drivers tend to rate themselves as more skillful and less risky than the average driver, and to extend the range of driver characteristics on which such ratings are made. A total of 178 male and female drivers rated "me as a driver," "an average driver" and "a very good driver" on the following eight relevant bipolar semantic differential scales: foolish-wise, unpredictable-predictable, unreliable-reliable, inconsiderate-considerate, dangerous-safe, tense-relaxed, worthless-valuable, irresponsible-responsible. The results confirmed expectations that a substantial majority of drivers, up to 80%, would rate themselves above average on a number of important characteristics, but also showed that they rated themselves below "a very good driver." The ratings did not vary significantly across demographic categories. Implications for road safety are briefly discussed.

Adult↗
PubMed1986

Vaginal prosthesis for control of vesicovaginal fistula.

A technique for construction of a vaginal appliance to control urinary incontinence secondary to a vesicovaginal fistula associated with pelvic malignancies and/or radiation therapy is described and illustrated.

Carcinoma, Squamous Cell↗
PubMed1986

Effect of ribavirin and tributylribavirin on argentine hemorrhagic fever (Junin virus) in guinea pigs.

Subcutaneous injections of ribavirin into guinea pigs infected intraperitoneally or intracerebrally with Junin virus significantly increased the mean time to death but did not enhance survival of the animals. We found similar results with tributylribavirin. Virus replication was delayed, but not prevented, in ribavirin-treated infected guinea pigs. The animals usually died with high virus titers in their brains and frequently were paralyzed.

Animals↗