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Biomedical subjects

R Shapiro

Publications and source records attributed to R Shapiro.

At least 433 records · Page 24Linked to original sources
PubMed1976

Interference by 2, 3-dimercapto-1-propanol (BAL) in angiotensin I radioimmunoassay.

The angiotensinase inhibitor 2,3-dimercaptopropanol (BAL) interferes with peptide-antibody binding when certain sensitive antisera are used in angiotensin I radioimmunoassay systems. Three of nine antisera tested showed sufficient interference to produce serious errors in data obtained using these antisera together with BAL. For PRA determinations in human plasma, at both pH 5.7 and pH 7.3, relationships between different PRA'S are altered, and results of renin stimulation tests are changed in unpredictable ways. Determination of renin concentration in rat plasma does not require use of BAL as inhibitor, and it is best avoided. For human plasma renin determinations, use of BAL-sensitive antisera should be avoided, since there is no satisfactory way to correct data for the resulting error. BAL itself, rather than its oxidation products, is probably the interfering substance. The interference appears to be due to an interaction between BAL and the BAL-sensitive antiserum. It is not related to the known actions of BAL as chelating or reducing agent.

Angiotensin II↗
PubMed1976

Influence of renal dysfunction on warfarin plasma protein binding.

The in vitro plasma protein binding of warfarin was evaluated by ultrafiltration in plasma from seven normal subjects and seven patients with varying degrees of renal dysfunction. The unbound, or free, warfarin fraction was twice as high in the plasma samples withdrawn from patients with renal impairment than in the samples obtained from normal volunteers. Furthermore, there was a positive correlation between the extent of renal dysfunction and the magnitude of the free warfarin fraction when either creatinine clearance, plasma creatinine, or BUN was used to estimate renal function.

Adult↗
PubMed1975

Isolation of soluble elastin from lathyritic chicks. Comparison to tropoelastin from copper deficient pigs.

Tropoelastin was isolated from the aortas of chicks rendered lathyritic by treatment with beta-aminopropionitrile. The soluble elastin was judged homogeneous by sodium dodecyl sulfate polyacrylamide gel electrophoresis and possessed an estimated molecular weight of 70000. Automated sequential analysis revealed that the N-terminal region of the chick tropoelastin is very homologous to tropoelastin isolated from copper-deficient piglets. N-terminal analysis of a trypsin digest of chick tropoelastin showed that tyrosine frequently is found adjacent to lysine residues. This positioning of tyrosine residues may be significant in terms of a possible regulatory role in elastin cross-link formation.

Amino Acid Sequence↗
PubMed1975

Modification of E. coli ribosomes and coliphage MS2 RNA by bisulfite: effects on ribosomal binding and protein synthesis.

The reaction of E. coli 70s ribosomes with 0.2 M NaH-35 s03 (pH 7.1, 3.5hrs, 37 degree) led to the conversion of 4.5% of the uracil residues of the R, RNA into 5.6-dihydrouracil-6-sulfonate residues. The modified ribosomes exhibited a significant decrease in their ability to bind (14-C)-phenylalanyl-(RNA-phe and to incorporate (14-C)-phenylalanine into protein in the presence of polyuridylic acid. The ability of the modified ribosomes to form an initiation complex as measured by the A-U-G or coliphage MS2 RNA dependent binding of (14-C)-fmet-tRNA-fmet was also impaired, as was their ability to incorporate (14-C) lysine into protein with MS2 RNA as messenger. Treatment os MS RNA with 0.2 M sodium (35-S) bisulfite, pH 7.0 at 25 degrees C resulted in the substitution of 2.7% and 6.2% of the uracil residues by bisulfite after 1 and 3.5 hrs of reaction, respectively. Impairment of function of the MS2 RNA in both initiation complex formation and transplantation assays was observed. These reactions of uracil residues of mRNA and rRNA may be a cause of biological damage inflicted by sodium bisulfite and sulfur dioxide.

Bacterial Proteins↗
PubMed1975

Methods for serial study of renin-angiotensin system in the unanesthetized rat.

Micromethods for measurement of plasma renin concentration (PRC) and plasma renin-substrate concentration (PSC) have been developed for rat plasma with radioimmunoassay of angiotensin I. An improved technique for aortic implantation of plastic cannulas was developed for use in experiments 1-2 wk in duration. The effects on components of renin system of anesthesia and tail cutting were studied. Arterial blood was sampled through cannulas without animal manipulation. PRC varied little in unanesthetized rats, was moderately and variably increased during pentobarbital anesthesia, and was markedly and consistently elevated during ether anesthesia. PSC was unchanged during anesthesia. PRC was increased in blood obtained by tail cutting within 1-2 min after cutting. With the use of the methods and techniques described here serial studies of the renin system in plasma of unanesthetized rats are shown to be feasible. A role for the sympathetic nervous system in the mediation of renin secretion by ether is proposed.

Anesthesia↗
PubMed1975

The association of cleidocranial dysostosis with hearing loss.

Three new cases of cleidocranial dysostosis with hearing loss are reported in this paper. The significant points concerning this association are: (1) the hearing deficit is predominantly a middle ear conduction problem secondary to structural abnormalities of the ossicles; (2) there is sometimes a small bone conduction deficit indicating either a cochlear or an eighth nerve problem; (3) the middle ear hearing loss was corrected surgically in one reported case; (4) there is dense sclerosis of the temporal bone which makes a middle ear operation technically difficult; and (5) hearing loss with cleidocranial dysostosis may be more common than the number of cases in the literature suggests.

Adult↗
PubMed1974

A simplified method for study of RNA conformation--reaction of formylmethionine transfer RNA with [14C]methylamine-bisulfite.

A new chemical method for radioactive labeling of single-stranded regions of RNA has been used to probe the three-dimensional structure of E. coli tRNA(fMet) in solution. The procedure involves conversion of cytosine residues to N(4)-[(14)C]methylcytosines by treatment with (14)CH(3)NH(2) and sodium bisulfite at pH7. Ribonuclease digestion of the modified tRNA produces (14)C-labeled oligonucleotides which comigrate with the corresponding unlabeled oligonucleotides, facilitating structural analysis. By this procedure, E. coli tRNA(fMet) has been found to contain only six reactive cytosines: C(1), C(16), C(17), C(35), C(75) and C(76). In addition, slow reaction at C(m) (33) was observed. These results are in excellent agreement with previously reported data on the sites of exposed cytosine residues in tRNA(fMet) obtained by two other chemical methods. The methylamine-bisulfite procedure is recommended for studying the ordered structure of more complex polyribonucleotides such as viral and ribosomal RNAs.

Artifacts↗