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Biomedical subjects

S Hall

Publications and source records attributed to S Hall.

At least 235 records · Page 13Linked to original sources
PubMed1984

Dihydrolipoamide dehydrogenase from halophilic archaebacteria.

Dihydrolipoamide dehydrogenase has been discovered in the halophilic archaebacteria for the first time. The enzyme from both classical and alkaliphilic halobacteria has been investigated. (1) The enzyme specifically catalysed the stoichiometric oxidation of dihydrolipoamide by NAD+. Enzymic activity was optimal at 2 M-NaCl and was remarkably resistant to thermal denaturation. (2) The relative molecular masses (Mr) of the native enzyme from the various species of halobacteria were determined to be within the range 112000-120000. (3) The enzyme exhibited a hyperbolic dependence of catalytic activity on both dihydrolipoamide and NAD+ concentrations. From these steady-state kinetic measurements the dissociation constant (Ks) of dihydrolipoamide was determined to be 57 (+/- 5) microM. (4) The enzyme was only susceptible to inactivation by iodoacetic acid in the presence of its reducing ligands, dihydrolipoamide or NADH. The rate of inactivation followed a hyperbolic dependence on the concentration of dihydrolipoamide, from which the Ks of this substrate was calculated to be 55 (+/- 7) microM. Together with the steady-state kinetic data, the pattern of inactivations is consistent with the involvement in catalysis of a reversibly reducible disulphide bond, as has been found in dihydrolipoamide dehydrogenase from non-archaebacterial species. In eubacterial and eukaryotic organisms, dihydrolipoamide dehydrogenase functions in the 2-oxo acid dehydrogenase complexes. These multienzyme systems have not been detected in the archaebacteria, and, in the context of this apparent absence, the possible function and evolutionary significance of archaebacterial dihydrolipoamide dehydrogenase are discussed.

Archaea↗
PubMed1984

Evaluation of the use of the argon laser in repairing rat and primate nerves.

The argon laser coagulates blood selectively, making it an adherent material. Argon laser energy is almost completely absorbed by red blood cells and does not seem to affect white nerve tissue. To demonstrate the technical feasibility of laser repair for severed nerves, we cut the sciatic nerves of rats and the median nerves of nonhuman primates and then repaired them by use of an argon laser beam delivered through a 400 microns optical fiber and handpiece that was developed in our laboratory. Autogenous blood was spread around the group of fascicles at the repair site and was then coagulated with the laser to form a minitubule around each fascicle group. Transmission and scanning electron microscopy showed that the repairs appeared technically superior to control sutured nerves and that the laser apparently had no untoward effects on either the repair site or on the control nerve. The minitubules seemed to channel the axon sprouts into the distal tubules extremely well and to prevent ingrowth of scar tissue at the juncture site.

Animals↗
PubMed1984

Voltage-dependent blockade of muscle Na+ channels by guanidinium toxins.

Na+ channels from rat muscle plasma membrane vesicles were inserted into neutral planar phospholipid bilayers and were activated by batrachotoxin. Single channel blocking events induced by the addition of various guanidinium toxins were analyzed to derive the rates of channel-toxin association and dissociation. Blocking by tetrodotoxin, saxitoxin, and six natural saxitoxin derivatives containing sulfate or hydroxyl groups were studied. Although the binding affinities vary over 2,000-fold, all of the toxins exhibit identical voltage dependence of the blocking reactions, regardless of the toxin's net charge. The results suggest that the voltage dependence of toxin binding is due to a voltage-dependent conformational equilibrium of the toxin receptor, rather than to direct entry of the charged toxin molecule into the applied transmembrane electric field.

Animals↗
PubMed1984

Systemic lupus erythematosus developing in patients with primary biliary cirrhosis.

Three patients with biopsy-proven primary biliary cirrhosis subsequently developed a multisystem disorder and serologic abnormalities consistent with systemic lupus erythematosus. In one patient, antimitochondrial antibody titers fell to undetectable levels after the development of the extrahepatic manifestations. No patient had been exposed to D-penicillamine or other drugs capable of inducing a lupus-like condition. These patients further emphasize the difficulties in disease classification and underline the systemic nature of chronic liver diseases such as primary biliary cirrhosis.

Adult↗
PubMed1984

Respiratory tract symptoms as a clue to giant cell arteritis.

Although many manifestations of giant cell arteries are increasingly recognized, little attention has been paid to respiratory symptoms associated with this disorder. We report the cases of 16 patients with giant cell arteritis who had prominent symptoms related to the respiratory tract including cough, sore throat, and hoarseness. These symptoms were the initial finding in 10 patients and obscured the diagnosis in some instances, but resolved quickly when corticosteroids were given. It is estimated that 9% of patients with giant cell arteritis have prominent respiratory tract symptoms, which are the initial manifestation in 4%. This disorder should be considered in an older patient with a new cough or throat pain without obvious cause.

Aged↗
PubMed1984

Occlusive retinal vascular disease in systemic lupus erythematosus.

Ocular involvement in patients with systemic lupus erythematosus (SLE) is most commonly noted in the form of retinal hemorrhage, exudates and cotton wool spots resulting from occlusion of small retinal blood vessels. Less frequently, SLE is associated with extensive obliteration of larger retinal vessels, as demonstrated in the 2 cases reported here. In both cases large parts of the retina lost their function due to extensive occlusions of retinal arteries and veins. Marked retinal neovascularizations developed in one of the 2 cases. Awareness and early detection of retinal vascular occlusive disease and its complications are important in averting serious visual loss in SLE.

Adolescent↗
PubMed1984

Relationship between renal clearance, protein binding and urine flow for digitoxin, a compound of low clearance in the isolated perfused rat kidney.

An isolated perfused rat kidney preparation is described which allows the relationship between protein binding and renal clearance to be studied in a quantitative manner. The influence of unbound fraction of drug in the perfusate, urine pH and urine flow upon the renal clearance of digitoxin is examined. Renal clearance and unbound fraction were found to be related linearly. Urine pH did not influence digitoxin renal clearance but urine flow did, in a nonlinear manner. A simple physiologically based model of renal clearance is developed which predicts the influence of urine flow and protein binding upon digitoxin clearance in this preparation.

Animals↗
PubMed1983

The therapeutic impact of temporal artery biopsy.

To evaluate the clinical usefulness of temporal artery biopsy in the diagnosis of giant-cell arteritis we followed up all 134 residents of Olmsted County, Minnesota, who had temporal artery biopsies between 1965 and 1980. Initial biopsies were positive for giant-cell arteritis in 46 cases and negative in 88. A history of jaw pain or claudication and the findings of a palpably abnormal temporal artery were significantly more common in the patients whose biopsy specimens showed giant-cell arteritis. Over a median follow-up period of 70 months (range 1-192) only 8 of the 88 biopsy-negative patients had clinical courses requiring long-term, high-dose corticosteroid therapy for giant-cell arteritis. In this population-based study temporal artery biopsy correctly predicted the subsequent need for corticosteroid therapy in 94% of cases: these findings indicate that biopsy should be done before patients are committed to long-term corticosteroid therapy.

Adrenal Cortex Hormones↗
PubMed1983

Efficacy of amdinocillin and lack of nephrotoxicity when combined with a second beta-lactam antibiotic for therapy of serious gram-negative bacillary infections.

Seventy-eight patients with serious gram-negative bacillary infections were assigned at random to receive either amdinocillin or an aminoglycoside. In addition, each patient was also given a broad-spectrum penicillin or cephalosporin antibiotic. The clinical response to treatment was comparable in the two groups. Cures were effected in 35 (92 percent) of 38 patients treated with amdinocillin and a beta-lactam antibiotic, compared with 37 (93 percent) of 40 patients who were treated with an aminoglycoside/beta-lactam combination. For the entire group, only five (7 percent) of the 75 infecting organisms were resistant in vitro to the treatment beta-lactam or amdinocillin combination, and similarly only two (3 percent) organisms were resistant to the treatment aminoglycoside (p = 0.44). Although drug-related toxicity occurred with equal frequency in the two groups, six patients treated with an aminoglycoside experienced nephrotoxicity compared with none of the patients who received amdinocillin (p = 0.034). Thus, amdinocillin plus a broad-spectrum beta-lactam antibiotic may provide suitable empiric therapy for many patients with presumed gram-negative infection and so avoid the risk of aminoglycoside-induced nephrotoxicity.

Adult↗