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Biomedical subjects

W S Lin

Publications and source records attributed to W S Lin.

At least 73 records · Page 4Linked to original sources
PubMed1977

Blindness of cerebral origin in acute intermittent porphyria. Report of a case and postmortem examination.

Sudden permanent blindness of cerebral origin, in addition to severe abdominal pain, hypertension, convulsions, and peripheral neuropathy developed in a 21-year-old woman, a victim of acute intermittent porphyria. Findings of the pathological examination of the brain showed extensive infarction in both occipital lobes. The pathological changes were consistent with anoxia. We discuss and review the literature of the possibility of "vasospasm" of both posterior cerebral arteries. Follow-up studies with serial EEG showed either focal epileptogenic activity or diffuse slow waves. The most consistent epileptic discharges were found in the occipital regions. The favorable response to the treatment of seizures with carbamazepine in this patient might encourage further clinical trials.

Adult↗
PubMed1975

The repair, protection and sensitization of papain with respect to inactivation by H2O2 and OH: effects of dithiothreitol, penicillamine, cystine and penicillamine disulphide.

While dithiothreitol repairs the peroxide-produced sulphenic acid derivative of papain in a fast reaction involving only one dithiothreitol molecule, penicillamine reacts with it to form papainCys25SSPen. Disulphide is also formed in the absence of peroxide (see article) by reactions of papainCys25S- AND PenS- radicals derived from -OH reactions in penicillamine-papain mixtures. A similar formation of papainCys25SSCys occurs in mixtures of cysteine and papain. However, unlike papainCys25SSCys, papainCys25SSPen cannot easily be restored to the active form of papain by the exchange reaction with CysSH, and this may have significance for an understanding of the sensitizing action of penicillamine observed in some in vivo systems. Under the action of OH radicals dithiothreitol has less of a tendency to form mixed disulphides and is more effective in repairing papain-OH intermediates than either cysteine or penicillamine. Due to secondary reactions of RSOH and other oxidized species the disulphides of cysteine and penicillamine are less effective than the sulphydryls in protecting papain against inactivation by -OH.

Cystine↗
PubMed1975

Formation and repair of papain sulfenic acid.

The inactivation of highly purified papain (2 times 10- minus 5M-minus 1 min-minus 1) for papain: peroxide molar ratios of 1:1 or 2:1. Loss of activity is accompanied by a parallel loss of sulfhydryl; however, the sulfhydryl losses, as determined with 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNG) or p-hydroxymercuribenzoate (pHMB), are anomalously either too large or too small, respectively. These discrepancies resulted from the reaction of inactive papain with either the thiol anion product of the DTNB reaction, or with the pHMB reagent itself. The addition of 1.2M urea to the DTNB reaction mixture significantly decreased this error. Inactive papain reacted with high concentrations of cysteine or cyanide to yield completely repaired active papain, and with benylamine to yield non-repairable, inactive papain. Sodium arsenite, which is capable ofreducing sulfenic acids but not disulfide bonds, readily repaired peroxide-inactivated papain. A completely inactive but repairable papain fraction was isolated by virtue of its lessened ability to bind to a tetrapeptide inhibitor immobilized on Sepharose. The cumulative results indicate that the peroxide inactivation of papain is due almost exclusively to the formation of papain sulfenic acid (Cys25-SOH).

Arsenic↗