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R J Wityk

Publications and source records attributed to R J Wityk.

40 records · Page 3Linked to original sources
PubMed1984

Calcium-ATPase activity in cystic fibrosis erythrocyte membranes: decreased activity in patients with pancreatic insufficiency.

The activity of Ca-ATPase (Ca2+,Mg2+-ATPase, ATP phosphohydrolase, EC 3.6.1.3) was measured in erythrocyte membrane preparations from 37 cystic fibrosis patients, 27 with pancreatic insufficiency and 10 with pancreatic sufficiency, and from 24 healthy controls. The mean maximal calcium-stimulated specific activities, in the absence and presence of purified calmodulin, of the pancreatic sufficient patients (34.3 +/- 4.2 and 75.9 +/- 6.9 nmol/min/mg) was indistinguishable from that of controls (35.8 +/- 2.6 and 84.3 +/- 4.7 nmol/min/mg), while both activities of patients with pancreatic insufficiency were significantly decreased (28.9 +/- 1.3, p less than 0.02; 65.2 +/- 3.0, p less than 0.001) compared to the control group. Similarly, the mean erythrocyte membrane (Na + K)ATPase activity was decreased only for those patients with a history of steatorrhea and who clinically required pancreatic enzyme therapy and had low immunoreactive trypsin levels (10.6 +/- 0.8 versus control, 13.4 +/- 1.1, and pancreatic sufficient patients, 13.3 +/- 1.4 nmol/min/mg; p less than 0.025). No correlation was found between any of the ATPase activities and the clinical scores of the patients, suggesting the lack of significant contribution of general clinical status to the activities of those cation transporters.

Adolescent↗
PubMed1982

Transposon-mediated site-specific recombination: identification of three binding sites for resolvase at the res sites of gamma delta and Tn3.

The tnpR gene product, resolvase, of the transposable element gamma delta mediates site-specific recombination between two copies of gamma delta directly repeated on the same replicon, and it negatively regulates transcription of the tnpA (transposase) gene and its own gene. The recombinational site, res, and the regulatory region both are located in the tnpA-tnpR intercistronic region. In studying the interaction of purified resolvase with DNA fragments derived from gamma delta and the related transposon, Tn3, that span this region, we have demonstrated that three sites specifically bind resolvase. Site I overlaps the recombinational crossover point and both transcriptional promoters. Sites II and III cover most of the DNA between the crossover point and the translational start of the tnpR gene. These are the only binding sites we have detected in a region of about 400 base pairs centered on the crossover point. Studies of cointegrates that contain only part of the region that binds resolvase indicate that site I is not sufficient for efficient site-specific recombination and suggest that all three sites are probably required.

Binding Sites↗
PubMedDate not supplied

Diffusion-negative stroke: a report of two cases.

Diffusion-weighted MR imaging is generally thought to be highly sensitive for the diagnosis of acute stroke. We report two cases of hyperacute stroke with absence of changes on diffusion-weighted images within 4 hours of symptom onset. Follow-up studies, performed 4 days later, showed infarction in regions compatible with the clinical presentation and (in one case) with the initial perfusion deficit. These cases indicate that normal findings on diffusion-weighted images in patients with suspected cerebral ischemia do not rule out impending infarction.

Acute Disease↗