Search PubMed⌕ Search

Biomedical subjects

J C Allen

Publications and source records attributed to J C Allen.

At least 271 records · Page 15Linked to original sources
PubMed1977

Ca++-binding properties of cznine aortic microsomes: lack of effect of c-AMP.

Ca++-binding to a microsomal fraction canine aorta has been studied and compared to Ca++-binding to canine cardiac microsomes. The aortic microsomes bound up to 60 nmoles Ca++/mg protein with a first-order binding rate constant of 0.025 sec-1. The binding rate of 5 sec was about half that of cardiac microsomes, 8 versus 15 nmoles/mg. The Ca++-binding to the aortic microsomes had a pH optimum of 7.4, was inhibited by monovalent cations and showed ATP preference when compared to other nucleotides. The binding was not stimulated by the presence of oxalate. c-AMP stimulated incorporation of 32P into the preparation, but had no effect on Ca++-binding.

Adenosine Triphosphatases↗
PubMed1977

Recent advances in cardiac glycoside-Na+,K+-ATPase interaction.

Na+,K+-ATPase has been purified from lamb kidney and consists of two polypeptide peaks on polyacrylamide gel electrophoresis with an enzyme activity of 1,000 mumole Pi/mg pro per hr. A scheme depicting the interaction of cardiac glycoside with the enzyme and ligand effects on binding has been constructed. Under all ligand conditions, ouabain binding tends to reach the same maximum if sufficient ouabain is present. Initial rates vary with ligand conditions. Using a chase method, the rate of dissociation of the glycoside from the enzyme is not influenced by the ligands present, although with separation of the enzyme-glycoside complex from the binding medium, differences are noted. The effect of ouabain on Na binding demonstrated two classes of sites, KD = 0.2 mM and KD = 18 mM. Denaturation decreased the high affinity sites. There was also a good correlation between ouabain binding and inhibition of Na binding. Clearly, ligands are critical in regulating cardiac glycoside interaction with the enzyme.

Adenosine Triphosphatases↗
PubMed1976

Incidence of photophobia in peripheral and sector iridectomy.

Fifth patients had bilateral intracapsular cataract extractions with a peripheral iridectomy in one eye and a sector iridectomy in the opposite eye. There was no difference in photophobia between the two eyes in 78% of patients. Twelve percent of the patients had greater photophobia in the eye with the peripheral iridectomy, and 10% had greater photophobia in the eye with the sector iridectomy.

Adult↗
PubMed1976

Cerebrospinal fluid T and B lymphocyte kinetics related to exacerbations of multiple sclerosis.

Cerebrospinal fluid T and B lymphocyte populations were identified in 21 patients with relapsing and 10 patients with stable multiple sclerosis. The results indicate that the percentage of T cell is largest in the acute stage of a relapse (65 percent) and diminishes by the second week (41 percent). Conversely, the stable patients had a lower percentage of T cells (30 percent) and a relatively high percentage of nonreacting cells (66 percent). The proportion of T cells in the cerebrospinal fluid varies directly with the clinical activity of the disorder, further implicating cellular immune mechanisms in the pathogenesis of multiple sclerosis.

Adult↗
PubMed1976

Minocycline.

Minocycline has proved to have a wider spectrum of activity against both aerobic and anaerobic bacteria and has enhanced tissue penetration when compared with its tetracycline congeners. The latter, and possibly the former, can be related to its increased lipophilicity in the physiologic pH range. It appears to be a superior chemoprophylactic agent against sulfonamide-resistant meningococci that do not become minocycline resistant as a result of treatment. The clinical promise of this agent has been dimmed, however, by recent reports of vestibular toxicity manifest in ambulatory patients. Though data on the frequency and severity of these symptoms are in some conflict, minocycline cannot currently be recommended for general clinical use.

Anaerobiosis↗
PubMed1975

Antigenic heterogeneity among pyocins of Pseudomonas aeruginosa.

We investigated the effect of FeSO4 on phagocytosis-associated, increased oxidative metabolism via the hexose monophosphate shunt, with special attention to its effect on H2O2 levels. The availability of glutathione peroxidase and glutathione reductase for H2O2 disposal and hexose monophosphate shunt stimulation also are evaluated. The results show an impairment of phagocytosis-associated hexose monophosphate shunt activity together with an increase both of resting and phagocytosing formate oxidation. These apparently paradoxical findings are resolved by demonstrating a direct enhancement of formate oxidation by FeSO4 in a cell-free system. In addition, measurement of H2O2 concentrations via scopoletin fluorescence shows reduction of H2O2 by FeSO4. There is no effect on either glutathione peroxidase or glutathione reductase activities. These data suggest that one mechanism of FeSO4 impairment of microbicidal activity is by its removal of H2O2.

Absorption↗
PubMed1975

The nature of the transport adenosine triphosphatase-digitalis complex. VIII. The relationship between in vivo-formed (3-H-ouabain-Na+, K+-adenosine triphosphatase) complex and ouabain-induced positive inotropism.

Ouabain interaction with a possible pharmacologic receptor, Na+, K+-adenosine triphosphatase (Na+, K+-ATPase), has been assessed by continual perfusion of canine hearts with various concentrations of both unlabeled and 3-H-ouabain. A positive dose-related correlation between enzyme inhibition, increased contractile force and drug binding to the enzyme has been established. The complex formed between 3-H-oubain and Na+, K+-ATPase in vivo appears to have the same characteristics as that formed in vitro, suggesting that the nature of both complexes is the same. These data are consistent with the concept that Na+, K+-ATPase may be an important pharmacologic receptor for cardiac glycosides.

Adenosine Triphosphatases↗