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Biomedical subjects

J Jefferson

Publications and source records attributed to J Jefferson.

9 recordsLinked to original sources
PubMed1992

Optimal stimulation of paralyzed muscle after human spinal cord injury.

Muscle properties change profoundly as a result of disuse after spinal cord injury. To study the extent to which these changes can be reversed by electrical stimulation, tibialis anterior muscles in complete spinal cord-injured subjects were stimulated for progressively longer times (15 min, 45 min, 2 h, and 8 h/day) in 6-wk intervals. An index of muscle endurance to repetitive stimulation doubled (from 0.4 to 0.8), contraction and half-relaxation times increased markedly (from 70 to approximately 100 ms), but little or no change was measured in twitch or tetanic tension with increasing amounts of stimulation. The changes observed with 2 h/day of stimulation brought the physiological values close to those for normal (control) subjects. A decrease in the stimulation period produced a reversal of the changes. No effects were observed in the contralateral (unstimulated) muscle at any time, nor was there evidence of decreased numbers of motor units in these subjects secondary to spinal cord injury. Motor unit properties changed in parallel with those of the whole muscle. The occasional spasms occurring in these subjects are not sufficient to maintain normal muscle properties, but these properties can largely be restored by 1-2 h/day of electrical stimulation.

Adaptation, Physiological↗
PubMed1988

Homozygous hypobetalipoproteinemia: a disease distinct from abetalipoproproteinemia at the molecular level.

apoB DNA, RNA, and protein from two patients with homozygous hypobetalipoproteinemia (HBL) were evaluated and compared with normal individuals. Southern blot analysis with 10 different cDNA probes revealed a normal gene without major insertions, deletions, or rearrangements. Northern and slot blot analyses of total liver mRNA from HBL patients documented a normal size apoB mRNA that was present in greatly reduced quantities. ApoB protein was detected within HBL hepatocytes utilizing immunohistochemical techniques; however, it was markedly reduced in quantity when compared with control samples. No apoB was detectable in the plasma of HBL individuals with an ELISA assay. These data are most consistent with a mutation in the coding portion of the apoB gene in HBL patients, leading to an abnormal apoB protein and apoB mRNA instability. These results are distinct from those previously noted in abetalipoproteinemia, which was characterized by an elevated level of hepatic apoB mRNA and accumulation of intracellular hepatic apoB protein.

Apolipoproteins B↗
PubMed1987

Experimental evidence for a neural origin of Ewing's sarcoma of bone.

The histogenesis of Ewing's sarcoma remains unknown. Recent studies have suggested a relationship to an unusual form of childhood neural tumor, often termed peripheral neuroepithelioma or primitive neuroectodermal tumor. Five Ewing's sarcoma tumor cell lines were studied for evidence of a neural phenotype. Under normal culture conditions, no morphologic evidence of neural differentiation was detected. Treatment with retinoic acid, an agent known to induce marked neural differentiation in neuroblastoma, had no demonstrable effect. Treatment with either cyclic AMP or TPA, in contrast, induced pronounced morphologic evidence of neural differentiation. Cells developed elongate processes with varicosities by phase-contrast microscopy; filaments, microtubules, and uraniffin-positive dense core granules were present by electron microscopy. Three neural markers (NSE, NFTP, and cholinesterase) were absent or barely detectable in untreated cells, but became abundant after treatment. These results provide convincing evidence for a neural histogenesis of Ewing's sarcoma. They also suggest a close relationship between Ewing's sarcoma and peripheral neural tumors, including the chest wall tumor described by Askin, but only a distant relationship to neuroblastoma.

Adolescent↗
PubMed1979

Central neural blockade and caesarian section II: patient assessment of the procedure.

A confidential questionnaire was sent to 62 mothers who had chosen central neural blockade for caesarian section. 82.5% replied to open and closed questions about their motives for and memories of the experience. Despite several sources of discomfort during surgery and in the postoperative period the overall response was overwhelmingly positive towards the procedure. The results of this pilot study indicate the importance of considering maternal aspirations prior to caesarian section, and allowing the informed mother to choose between central neural blockade and general anaesthesia whenever possible.

Anesthesia, Epidural↗
PubMed1978

Lack of effect of bromocriptine on ACTH levels in patients with bilateral adrenalectomy for pituitary-dependent Cushing's syndrome.

Bromocriptine lowers plasma ACTH levels in patients with pituitary-dependent Cushing's syndrome. It seemed possible that the drug would also be effective in patients who had been adrenalectomised for the disease. The effect of 5.0 mg of bromocriptine on plasma ACTH and prolactin levels in 13 patients, bilaterally adrenalectomised for pituitary-dependent Cushing's syndrome, was therefore studied. In only one patient was a fall in plasma ACTH observed. This may be of doubtful significance since marked spontaneous fluctuation in plasma ACTH levels were found in the five patients tested. Bromocriptine lowered the plasma prolactin in all of the patients, including two with hyperprolactinaemia.

Adolescent↗