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A Abrams

Publications and source records attributed to A Abrams.

At least 37 records · Page 2Linked to original sources
PubMed1981

Purification and characterization of the membrane adenosine triphosphatase complex from the wild-type and N,N'-dicyclohexylcarbodiimide-resistant strains of Streptococcus faecalis.

We have purified the F1-F0 adenosine triphosphatase complex from wild-type Streptococcus faecalis ATCC 9790 and an N,N'-dicyclohexylcarbodiimide (DCCD)-resistant mutant strain, SF-dcc-8. For preliminary purification of the complex, reconstituted F1-F0, prepared from isolated F1 adenosine triphosphatase and depleted membranes, was extracted with sodium deoxycholate and fractionated by salt precipitation. By means of two-dimensional gel electrophoresis, the F1-F0 complex was purified as a single, catalytically active band in the first dimension and then resolved into constituent subunits under denaturing conditions in the second dimension. The electrophoretic purification of F1-F0 removed a delta-less form of F1 as well as other impurities, including lipoteichoic acid. Both the DCCD-sensitive and the DCCD-resistant F1-F0 adenosine triphosphatase appeared to consist of eight proteins, five of which corresponded to the F1 subunits alpha, beta,, gamma, delta, and epsilon. The F0 sector proteins, designated M27, M15, and M6, had Mr values of 27,000, 15,000, and 6,000, respectively. There appear to be multiple copies of M6 in the complex. [14C]DCCD reacted specifically and covalently with M6 in the wild-type F1-F0 but failed to label the M6 protein in the complex from the DCCD-resistant strain. It is suggested that DCCD resistance in the SF-dcc-8 mutant may be due to a modification of the M6 protein which hinders access of DCCD to the reactive site.

Adenosine Triphosphatases↗
PubMed1979

Liver function values in adults receiving total parenteral nutrition.

A retrospective review was made of results of conventional liver function tests in adult patients who received fat-free total parenteral nutrition (TPN) for two weeks or longer and who did not have other obvious causes for liver function abnormalities. A "meaningful" increase (greater than or equal 50% increase above baseline pre-TPN value) in SGOT levels was noted in 68% of patients, in alkaline phosphatase levels in 54%, and in serum bilirubin levels in 21% of patients. The median peak values for SGOT, alkaline phosphatase, and bilirubin were 3-, 1.9-, and 0.25-fold above the upper limit of normal, respectively. The median time interval of peak increase for each of the three tests was between 9 and 12 days after TPN was started. Liver biopsy specimens from four patients, taken when liver function values were abnormal, showed pronounced steatosis in three patients and mild periportal cholestasis in the fourth patient. The cause(s) of the elevated liver values is unknown, but possibilities include cellular damage, such as steatosis, and an "overshoot" of enzymes when starved patients are refed.

Adult↗
PubMed1978

Unresponsiveness of catatonic symptoms to naloxone.

A case report of a catatonic patient is presented. Because of the similarity of catatonia to the animal behavior produced by intracerebral administration of beta-endorphin, an endogenous opioid, naloxone was administered. No effect was observed with naloxone, whereas both amobarbital and diazepam were able to reverse catatonic behavior. Testing of catatonic patients with naloxone may help further elucidate naloxone's reported anti-psychotic properties.

Adult↗
PubMed1977

Negative naloxone effects in schizophrenic patients.

On the basis of the hypothesis that the opiate-like neuropeptides, such as beta-endorphin, may be involved in the etiology of schizophrenic symptoms, naloxone 1,2 mg and placebo were administered intravenously to 8 schizophrenic patients, using a double-blind, crossover design. Naloxone was not found to be different from placebo in effecting schizophrenic symptoms, including hallucinations and delusions.

Adult↗
PubMed1975

Studies of substructure and tightly bound nucleotide in bacterial membrane ATPase.

Highly purified preparations of Streptococcus faecalis ATPase contain a similar but inactive protein detected by prolonged polyacrylamide gel electrophoresis. The inactive protein appears to arise by proteolytic cleavage of the major subunits in the enzyme. By use of a new technique, subunit analysis in SDS gels was performed on the enzyme band and the inactive protein band excised from a polyacrylamide gel after electrophoresis. The results indicated that the ATPase has the composition alpha3beta3gamma in which alpha = 60,000, beta = 55,000, and gamma = 37,000 daltons. The inactive protein appears to have the composition (f)6 in which f = 49,000 daltons. There is also evidence that the enzyme band contains some slightly modified forms of the ATPase, such as alpha3beta2 (f)gamma. The inactive protein lacks the capacity for tight nucleotide binding. Our experiments show that the tight ATPase-nucleotide complex formed in S. faecalis cells (the endogenous complex) behaves differently from the tight complex formed in vitro (the exogenous complex). We prepared a doubly labeled complex containing endogenous 32P-labeled ADP and ATP and exogenous 3H-labeled ADP. We observed that the addition of free nucelotide to the doubly labeled ATPase displaced the exogenous bound ligand from the enzyme but not the endogenous bound nucleotide. We suggest that the displaceable and nondisplaceable forms of the tight ATPase-nucleotide complex correspond to two different conformational states of the enzyme.

Adenosine Diphosphate↗