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Biomedical subjects

G Hall

Publications and source records attributed to G Hall.

At least 163 records · Page 9Linked to original sources
PubMed1989

Factor VIII inhibitor in insulin-dependent diabetes mellitus.

Acquired factor VIII inhibitor was found in a 69-year-old white male with insulin-dependent diabetes mellitus. He presented with left lower abdominal pain and hematoma after a fall. Preoperative hemostasis studies were normal except for prolonged aPTT. Prolonged aPTT was not corrected by 1:1 mixture with normal fresh plasma and incubation showed further prolongation with time. Factor VIII:c was 3.5%. The inhibitor titer was 7.5 Bethesda units. The possible mechanism causing antibody to factor VIII was postulated to be an autoimmune process and/or increased immunogenicity owing to glycosylation of factor VIII coagulant protein.

Aged↗
PubMed1989

Attenuation of latent inhibition after compound pre-exposure: associative and perceptual explanations.

Three experiments used rats as subjects and the conditioned emotional response (CER) paradigm to examine the effect of pre-exposure to a compound stimulus on the extent of latent inhibition to an element of that compound. In Experiment 1a a group of rats exposed to a compound that comprised a tone and a click exhibited less latent inhibition to the tone than did a group that had received pre-exposure to the tone in isolation. Experiment 1b showed that pre-exposure to the tone/click compound also resulted in an attenuation of latent inhibition to the click relative to a group that was pre-exposed to the click in isolation. Experiment 2 demonstrated that latent inhibition to the tone was left intact following pre-exposure to the tone in compound with a light. This pattern of results seems to be most plausibly explained in terms of the presence and absence of generalization decrement following compound pre-exposure.

Animals↗
PubMed1989

New trends in antibiotic prophylaxis of infective endocarditis in patients undergoing surgery in the oral cavity.

Viridans-streptococci, which normally reside in the oral cavity, are still the most common pathogens in infective endocarditis. During surgical procedures in the oral cavity, pharynx and respiratory tract, microorganisms may disseminate into the blood and cause infective endocarditis in predisposed patients. It is, therefore generally considered that these patients should be protected during surgery by an effective and simple antibiotic regimen. During recent years new recommendations for prevention of endocarditis have been presented in several countries. Single high dose amoxycillin or 2-dose phenoxymethylpenicillin are used in normal risk patients while 2-dose erythromycin or single high dose clindamycin may be used in patients allergic to penicillins. Parental agents are usually recommended in high risk patients with prosthetic heart valves, however, some countries prefer to administer peroral prophylaxis. Topical prophylaxis in the oral cavity is not included in any national recommendation, but may decrease the magnitude, as well as the frequency, of postsurgical bacteremia. Commonly used antiseptics such as chlorhexidine are not selective enough and causes overgrowth of some viridans-streptococci. More selectively acting agents, such as topical vancomycin, appear to be more suitable.

Anti-Bacterial Agents↗
PubMed1989

Acquired equivalence and distinctiveness of cues.

In Experiments 1 and 2, rats received initial training in which two stimuli (A and N) were either followed by the same consequence (food) or by different consequences (food and no food). Subsequently N was paired with electric shock and the generalization of conditioned suppression to A was assessed. Suppression to A was more marked when A and N had both been followed by food than when they had had different outcomes. In Experiment 3, 3 stimuli (A, B, and N) were presented initially. For one group, A and N were paired with food and B was nonreinforced: for a second group, B was paired with food and A and N were nonreinforced. Generalization of suppression was found to be more substantial to A than to B for both groups. These results indicate that the extent to which stimuli are treated as being equivalent is partly determined by their reinforcement histories.

Animals↗
PubMed1988

Transforming growth factor-beta is a potent immunosuppressive agent that inhibits IL-1-dependent lymphocyte proliferation.

Transforming growth factor-beta (TGF-beta), a product of neoplastic and hemopoietic cells, is a bifunctional regulator of the immune response. At femtomolar concentrations, TGF-beta stimulates monocyte migration, and picomolar quantities induce synthesis of monocyte growth factors, including IL-1, that may promote tissue repair by regulating fibrosis and angiogenesis. Paradoxically, TGF-beta at picomolar concentrations also blocks the ability of IL-1 to stimulate lymphocyte proliferation. At 0.01 to 1.0 ng/ml, TGF-beta 1 and its homologue, TGF-beta 2, suppress the IL-1-dependent murine thymocyte proliferation assay. TGF-beta also inhibits human peripheral blood T lymphocyte mitogenesis. Inhibition of cell division appears to occur after activation of the lymphocytes inasmuch as neither gene expression nor translation of IL-2R is suppressed. Furthermore, TGF-beta does not block synthesis of IL-2. Therefore, TGF-beta 1 and TGF-beta 2 likely act at a site distal to IL-1 to block lymphocyte DNA synthesis. These findings suggest that TGF-beta secreted in an inflammatory site may be beneficial in diminishing lymphocyte function while promoting fibrosis and tissue repair. However, TGF-beta generated by neoplastic tissues may provide a mechanism for unrestricted tumor cell growth through its selective immunosuppressive effects.

Humans↗
PubMed1988

The effect of low-energy infra-red laser radiation on wound healing in rats.

The aim of this study was to evaluate the effect of low-energy infra-red laser treatment on wound healing in rats, both histologically as well as by gross observation. In the caudal area of the back of 14 rats, identical full thickness dermal wounds were punched out bilaterally. One wound in each rat was randomly selected for laser radiation. The contralateral wound was left untreated, serving as a control. All the laser-treated wounds and the untreated control wounds healed in the same way within the same period of time. No difference was observed concerning bleeding time, nor as to the formation and loss of crust. None of the wounds showed signs of infection during the observation period. Histological examination indicated no obvious morphological difference between the laser-treated and the untreated wounds. The present study did not confirm that the use of low-energy infra-red laser radiation could improve the wound healing process.

Animals↗
PubMed1988

Learning in rats with caudate-putamen lesions: unimpaired classical conditioning and beneficial effects of redundant stimulus cues on instrumental and spatial learning deficits.

The effects of caudate-putamen lesions in the rat on conditioning were investigated in three experiments. In Experiment 1, rats with lesions were impaired on a spatial task that required learning to make the correct position response, but no deficit was obtained when the alternatives were differentiated by salient visual cues. Performance remained good even when the visual cues were removed. A classical conditioned suppression paradigm was used in Experiment 2, and caudate-putamen lesions were found not to impair acquisition of suppression or overshadowing. In Experiment 3 we revealed poor instrumental learning in subjects with lesions as retarded acquisition of lever-press responding and depressed variable interval response rates. When a light stimulus was present together with reinforced responses, response rates were depressed in the control group (which suggested an overshadowing phenomenon) but were potentiated in the group with lesions. The results showed that caudate-putamen lesions did not produce a general deficit in association formation. There was disruption of learning about responses but not stimuli and, moreover, it was found that redundant stimulus cues aided response learning. It appears that for normal subjects, the salience or associability of the response cues may largely determine the influence of stimuli presented during instrumental conditioning.

Animals↗
PubMed1988

[The biological monitoring of ecologic cadmium exposure in the free state of Bavaria].

In 1984/1985 631 blood-donors settled in different regions of Bavaria took part in a "cadmium-campagne". Due to this project a substantial medical anamnesis was made and blood has been investigated to determine the cadmium level, furthermore, urine was taken for the determination of cadmium, total protein, beta 2-microglobulin, creatinine and density. In conformity with recent epidemiological investigations in Europe it was evident that the actual internal cadmium exposure - in relation to the cadmium level in blood - has not increased. Subsequently a not acceptable accumulation was excluded accordingly to the result of the proofed renal excretion of cadmium. In consideration of the established low cadmium level in biological material there was no impairment of the kidneys due to cadmium. This is also obvious in the total protein- and beta 2-microglobulin-excretions in urine which are in the normal range. By dividing the collective according to smoking habits this study confirmed, that higher values have been linked with the smokers. However, as to the age and sex there were no significant influences. The evaluation of a regional subdivision of the received samples in overcrowded regions, rural and areas far from industry did not show notable differences. Furthermore, a differentiated aspect was seen after the classification into domiciles, whereby 8 different cities, small towns and villages, resp., were considered. Despite of various differences it must be pointed out, that the cadmium level in blood as well as in urine is below the normal levels with some exceptions only. This study did not show criteria for a risk caused by cadmium which effects the general population of Bavaria.

Adult↗
PubMed1988

Evaluation of a combination of xylazine, ketamine, and halothane for anesthesia in llamas.

Anesthesia induced by use of a combination of xylazine, ketamine, and halothane, under conditions of spontaneous and mechanically controlled ventilation, was evaluated in 5 llamas positioned in dorsal recumbency. Using chronically implanted catheters, systemic arterial blood pressure, pulmonary arterial pressure, right atrial pressure, heart rate and rhythm, cardiac output, blood pH and gas tensions, body temperature, and respiratory rate were measured before anesthesia induction (baseline), throughout the anesthetic period, and for 1 hour into the recovery period. During anesthesia, llamas undergoing spontaneous ventilation developed hypercapnia and respiratory acidosis. Cardiovascular function was decreased during both types of ventilation. The combination of xylazine, ketamine, and halothane in various doses and 2 ventilation procedures (spontaneous and controlled) provided a reliable method for general anesthesia in llamas, but marked cardiovascular depression developed during anesthesia maintenance with halothane. Spontaneous ventilation resulted in potentially clinically important respiratory acidosis.

Anesthesia, General↗
PubMed1987

Nosocomial clonal dissemination of methicillin-resistant Staphylococcus aureus. Elucidation by plasmid analysis.

An outbreak of methicillin sodium-resistant Staphylococcus aureus (MRSA) infection and colonization, mainly centered in the vascular surgery service, occurred in a 1000-bed tertiary care center between December 1983 and December 1984. Methicillin-resistant S aureus isolated before and during the outbreak was studied by both bacteriophage typing and by restriction endonuclease digestion of bacterial plasmid DNA. Bacteriophage typing was discrepant in nine (56%) of the 17 repeated analyses compared with one (3.4%) of the 29 for plasmid profiling. These typing methods revealed that the epidemic strain was introduced to the hospital from the community 15 months before the outbreak. The outbreak was caused by cross-transmission of the epidemic strain by health care personnel and was controlled by treatment of colonized personnel, education of personnel, and institution of barrier precautions for colonized or infected patients. Plasmid profiling with restriction endonuclease digestion was easier, more rapid, and more specific than bacteriophage typing in the evaluation of this outbreak.

Cross Infection↗
PubMed1987

DNA binding studies on 1OH-pyrrolizino[1,2-b]quinolines.

1OH-Pyrrolizino [1,2-b]quinolines exhibited intercalation when tested by the following methods: effect of DNA on spectral properties, spectrophotometric titration, fluorescence enhancement of homidium bromide (ethidium bromide), thermal denaturation of DNA, effect on covalently closed circular double stranded PM-2 (Col E 1 plasmid) DNA. Some of the compounds showed antiproliferative activity in HeLa cells.

Animals↗