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Biomedical subjects

D Pleasure

Publications and source records attributed to D Pleasure.

137 records · Page 8Linked to original sources
PubMed1978

Neuroma scar formation in rats following peripheral nerve transection.

Utilizing a sciatic nerve-transection model in rats, we studied the collagen content of normal control nerves, the long-term collagen accummulation in the distal stump of the transected nerve, the content of collagen of the posterior tibial nerve distal to the transection, and the myofibrosis of the gastrocnemius muscle. The distal stump of the sciatic nerve accumulated significant amounts of collagen with time but the posterior tibial nerve at a distance from the site of transection showed no progressive collagen accumulation. The histologically evident myofibrosis of the denervated gastrocnemius muscle was shown to be the result of a selective loss of muscle elements and not of an accumulation of collagen. cis-Hydroxyproline, a proline analogue, limited neuroma formation following neurorrhaphy. The findings suggest that the results of delayed repair of nerves should not be impaired by intraneural scarring if enough of the transected nerve beyond the point of intraneural scar formation is resected.

Animals↗
PubMed1977

Erythrocyte cation-activated adenosine triphosphatases in Duchenne muscular dystrophy.

The cation-stimulated adenosine triphosphatase (ATPase) activities of erythrocyte ghosts and erythrocyte ghost plasma membrane fragments of patients with Duchenne muscular dystrophy (DMD) were compared with activities in age-matched normal male controls. DMD Mg++-stimulated ATPase activity was within the normal range. The specific activity of DMD erythrocyte ghost Na+,K+-stimulated, Mg++-dependent ATPase was also normal, and was inhibited by 10(-4) M ouabain to an extent comparable with controls. Ca++-stimulated, Mg++-dependent ATPase activity of DMD erythrocyte ghost plasma membrane fragments, assayed at 0.5 mM free Ca++, was 21% above that in age-matched male controls (n = 22, 2-tailed paired t-test, P less than 0.01). Kinetic studies indicated that the DMD erythrocyte Ca++-stimulated, Mg++-dependent ATPase has greater affinity for MgATP than the enzyme in control erythrocytes.

Adenosine Triphosphatases↗
PubMed1976

Sterol synthesis by myelinating cultures of mouse spinal cord.

We studied the control of sterol synthesis during myelination of central nervous system in culture. Explants of fetal mouse spinal cord were cultured for 3-30 days in vitro (DIV). Myelination was visible by electron micriscopy at 3 DIV, and by bright-field light microscopy beginning at 6 DIV. All explants were heavily myelinated by 15 DIV. Specific activity of 2',3'-cyclic nucleotide-3'-phosphohydrolase (CNP) increased rapidly until 15 DIV. The rate of incorporation of [1-14C]acetate into sterol was greatest at 12 DIV, more than double that at 4 and 22 DIV. Specific activity of the mevalonate synthesizing enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG CoA reductase) was greatest at 11 DIV, threefold greater than at 6 and 30 DIV. Previous studies in fibroblasts and other non-neural tissues had shown that deprivation of exogenous lipid caused a rapid increase in HMG CoA reductase activity. In contrast, when the spinal cord explants were incubated for 24 h in a lipid-deficient medium, there was either a marked decrease in specific activity of HMG CoA reductase (at 6, 15 and 30 DIV), or no change in enzyme activity (at 11 DIV).

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1976

Glue sniffer's neuropathy.

Progressive sensorimotor neuropathy developed in two patients exposed to prolonged (chronic) inhalation of n-hexane (glue sniffing). Sural nerve biopsies showed loss of axons; remaining axons were either normal or showed accumulation of filaments of 90 to 100 A thick, widened nodes of Ranvier, and focal enlargements. The muscle biopsy revealed neurogenic atrophy. Intramuscular nerve twigs and end-plates, studied in one patient, showed loss of axons and nerve terminals. Unmyelinated axons also showed accululation of 60 to 100 A thick filaments. The similarities between the pathologic findings in the peripheral nerve of these patients and those with acrylamide neuropathy suggest that the n-hexane inhalation produces a dying back neuropathy.

Adult↗
PubMedDate not supplied

Regulation of Schwann cell nerve growth factor receptor by cyclic adenosine 3',5'-monophosphate.

Previous studies indicated that Schwann cells in immature nerves express nerve growth factor (NGF) receptors, and that this expression is down regulated during development but re-induced by Wallerian degeneration. It was also shown that immature Schwann cells are induced to express galactocerebroside and other molecules characteristic of mature Schwann cells by either contact with an axon or treatment with the cyclic adenosine 3',5'-monophosphate (cAMP) analogues dibutyryl cAMP (dbcAMP) and 8-bromo cAMP or the adenylate cyclase activator forskolin. In the present study, NGF receptors on the surface of cultured Schwann cells were demonstrated by binding of an anti-rat NGF receptor monoclonal antibody or of radioiodinated NGF. Treatment of cultured Schwann cells with cAMP analogues or forskolin resulted in a progressive decrease in both immunoreactive NGF receptors and radioiodinated NGF binding. The cultured Schwann cells contained a polyadenylated RNA species homologous with human melanoma NGF receptor mRNA in sequence and size. The amount of this NGF mRNA was lower in cAMP analogue-treated than in untreated Schwann cells.

8-Bromo Cyclic Adenosine Monophosphate↗