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Biomedical subjects

J Allen

Publications and source records attributed to J Allen.

At least 433 records · Page 24Linked to original sources
PubMed1977

Effects of neostigmine and pyridostigmine at the neuromuscular junction.

The effect of subcutaneous administration of pyridostigmine or neostigmine for 7 to 15 days on neuromuscular transmission has been studied in the rat phrenic nerve-hemidiaphragm preparation. The quantal contents of end-plate potentials at different stimulus rates and the amplitude and frequency of miniature end-plate potentials were compared with those of untreated controls. The rate of release of acetylcholine quanta at high stimulus rates, and the frequency of miniature end-plate potentials, were reduced by pretreatment with both pyridostigmine and neostigmine. Presynaptic effects differed in that the number of quanta released by each nerve impulse at a stimulus rate of 1/sec was not altered by pyridostigmine, but was reduced to 52% of normal by neostigmine. The amplitude of miniature end-plate potentials was reduced to 81% by pretreatment with neostigmine and to 54% by pretreatment with pyridostigmine. The cause appears to be a reduction in the number of acetylcholine receptor sites as a result of disorganisation of the postsynaptic muscle membrane, which may contribute to the muscular weakness associated with the long term use of anticholinesterase agents.

Animals↗
PubMed1977

Fibromuscular dysplasia as a cause of stroke in infancy and childhood.

Two children had abrupt onset of hemiplegia due to childhood fibromuscular dysplasia (FMD). Although FMD is a recognized cause of strokes in adults, the disorder has not, to our knowledge, been reported previously in children. Our report reviews the pathology and diagnosis of FMD and discusses the complexities of its treatment.

Cerebrovascular Disorders↗
PubMed1976

57-cobalt-bleomycin as a tumor scanning agent in primary hepatocellular cancer.

57Co-bleomycin and 99mTc-sulfur colloid scans were performed in 13 southern African black patients with primary hepatocellular cancer (PHC) and 3 patients with other space-occupying hepatic lesions. Selective concentration of 57Co-bleomycin in the defect or defects seen on the 99mTc-sulfur colloid scan occurred in only 4 of the 13 (31%) patients with PHC. In the remaining PHC patients, as well as in the 2 patients with metastatic liver disease and the 1 patient with an amebic liver abscess, the 57 Co-bleomycin and 99mTc-sulfur colloid scans were identical. 57Co-bleomycin appears to have only a limited place as a tumor-seeking agent in the diagnosis of PHC in southern African blacks.

Bleomycin↗
PubMed1976

Correction of leukocyte function in Chediak-Higashi syndrome by ascorbate.

Because ascorbate potentiates chemotaxis of normal leukocytes, we examined the effect of ascorbate on polymorphonuclear leukocytes from a patient with the Chediak-Higashi syndrome. Chemotactic migration was 104+/-16 leukocytes per 10 fields (mean+/-S.D.) initially and 258+/-44 (P less than 0.001) after ascorbate, as compared to 182+/-10 in controls. There was no bactericidal activity by 40 minutes in the patient's untreated leukocytes. After ascorbate bactericidal activity of patient and untreated control cells was the same. The addition of ascorbate reduced cAMP levels in the patient's cells from a mean of 34.5 pmoles per 10(7) polymorphonuclear leukocytes to 5.9, as compared to a control value of 3.1+/-1.4. The association of elevated cAMP and impaired function in the polymorphonuclear leukocytes of patients with the Chediak-Higashi syndrome may be related to abnormal microtubular assembly.

Ascorbic Acid↗
PubMed1976

Alterations in plasma sialyltransferase associated with successful chemotherapy of a disseminated tumor. Case report.

Levels of plasma sialyltransferase were measured in a patient with disseminated carcinoma of the testes. Initial enzyme values, elevated six fold above those in normal controls, were among the highest thus far encountered in a population of patients with various stages and types of malignancy. During a remarkable respose to chemotherapy with cis-diaminodichloroplatinum, plasma sialyltransferase levels fell markedly. Serial measurement of this enzyme may aid in evaluation of tumor responsiveness to therapy in patients whose disease is not readily measurable.

Adult↗
PubMed1976

Anxiety, self-concept, and personal and social adjustments in children with sickle cell anemia.

The psychologic effect of sickle cell anemia, a life-long chronic illness, on the self-concept, anxiety level, and personal and social adjustments of school-aged children was investigated by using a battery of standard psychologic tests. Two groups of children were evaluated: a study group of 29 children with sickle cell anemia (hemoglobin SS) and a comparison group of 26 black inner city schoolchildren without sickle cell disease or other known chronic illness. The youngsters with sickle cell anemia did not differ from a peer group of schoolchildren in personal, social, and total adjustments. The self-concept scores of the patient group were lower than those of the comparison group. An unexpected finding of the study was the observation that the anxiety scores (measuring acute anxiety) were significantly lower in the study group than those in the comparison group.

Adolescent↗
PubMed1976

The continual administration of neostigmine and the neuromuscular junction.

The effect of continual administration of neostigmine on the neuromuscular junction of the rat diaphragm was examined by determining the number of quanta of acetylcholine released by each nerve impulse, the effect of differing repetition rats on quantal release and the amplitude and frequency of miniature end-plate potentials. The number of quanta of acetylcholine released at a nerve impulse repetition rate of 1/sec was reduced to 51% of normal in treated animals. The reduction was greater at faster repetition rates. The amplitude of miniature end-plate potentials was reduced to 75% of normal. This reduction appears to be due to blocking of receptor sites rather than the reduction in the amount of acetylcholine in each quantum. The frequency of spontaneous miniature end-plate potentials was reduced in treated animals.

Acetylcholine↗
PubMed1975

Feather pecking and cannibalism in a caged layer flock.

1. The progress of feather pecking and cannibalism was recorded from hatching to end of lay in a flock of caged layers and the influence of group size, floor area allowance and cage tier upon the incidence of these activities during lay assessed. 2. The largest group suffered more cannibalism and feather pecking than smaller groups, floor area allowance and tier being less important factors. 3. A significant trend was found for one death from cannibalism to be followed by more in the same cage.4. It was concluded that feather pecking and cannibalism are separate phenomena, although the same cage conditions increased the incidence of both. 5. Cannibalism may be divided into vent pecking and cannibalism affecting other parts of the body, the former is independent of feather pecking and the latter, though usually preceded by feather pecking, is only indirectly associated with it.

Animals↗
PubMed1975

The syndrome of systemic carnitine deficiency. Clinical, morphologic, biochemical, and pathophysiologic features.

An 11-year old boy had had recurrent episodes of hepatic and cerebral dysfunction and underdeveloped musculature. Overt weakness developed at age 10. Lipid excess, especially in type I fibers, was found in muscle. Hypertrophied smooth endoplasmic reticulum and excessive microbodies were present in liver. Marked carnitine deficiency was shown in skeletal muscle, plasma, and liver. Ketogenesis was impaired on a high fat diet, but omega oxidation of fatty acids was enhanced. There was excessive glucose uptake and essentially no oxidation of labeled long-chain fatty acids by perfused forearm muscles in vivo. Oral replacement therapy restored plasma carnitine levels to normal, but not liver or muscle carnitine levels, and was accompanied by clinical improvement.

Adenosine Triphosphatases↗
PubMed1975

Elevated plasma sialyltransferase in the cancer patient.

Sialyltransferase activity was measured in plasma samples using desialated fetuin as the acceptor and cytidine 5'-phosphate-sialic acid as donor. The data show an increased enzyme level in 56 of 65 cancer patients studied, as compared with normal control values. The enzyme was not significantly elevated during lacation or in liver cirrhosis, but it was elevated in rheumtoid arthritis. Of the patients with cancer, 35 showed plasma enzyme levels above any value encountered in rheumatoid arthritis plasmas. The determinants of enzyme level in cancer appear to be complex: monitoring of plasma sialytransferase may be of value in measuring tumor progression, metatastatic involvement, or success of therapeutic programs.

Arthritis, Rheumatoid↗