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Biomedical subjects

S Perlman

Publications and source records attributed to S Perlman.

At least 127 records · Page 7Linked to original sources
PubMed1984

Mechanism for the high bias in the USP colorimetric assay for diazotizable substances in hydrochlorothiazide.

The USP XX colorimetric assay for the determination of diazotizable substances in hydrochlorothiazide was studied. Colorimetric assay results of hydrochlorothiazide bulk powder and captopril-hydrochlorothiazide combination tablets were found to have a high bias when compared with HPLC. A kinetic study of the diazotization step in the colorimetric assay and extrapolation of the free amine content, i.e., 4-amino-6-chloro-1, 3-benzenedisulfonamide, to time zero provided results which correlated favorably with those obtained by HPLC. The high bias of the colorimetric assay was shown to result from the formation of 4-nitroso derivative of hydrochlorothiazide, which is formed by acid hydrolysis during the diazotization step. Bendroflumethiazide and flumethiazide also showed increasing free amine content when the time of diazotization was increased.

Amines↗
PubMed1984

Citramalic acid in cerebrospinal fluid of patients with bacterial meningitis.

Cerebrospinal fluid (CSF) from uninfected patients and from patients with bacterial and viral meningitis was analyzed by gas-liquid chromatography, with use of a flame ionization detector, and by gas chromatography-mass spectrometry. The resulting profiles were consistent and reproducible. Hydroxy acids were the compounds found in greatest abundance in both normal and infected CSF. Control experiments to establish the sensitivity and efficiency of the extraction and derivatization methods are also presented. Constituents of CSF from patients with bacterial meningitis differed quantitatively and qualitatively from those of CSF from uninfected patients or patients with nonbacterial infections. CSF from seven of eight patients with bacterial meningitis contained citramalic acid, a compound not previously identified in either normal or infected CSF. The implications of these findings are discussed.

Adolescent↗
PubMed1983

Eye movements in Friedreich's ataxia.

Twenty-four patients with well-documented Friedreich's ataxia underwent quantitative oculomotor testing. A consistent pattern of eye movement abnormalities was observed. This pattern included fixation instability, inaccurate saccades with normal peak velocity, impaired smooth pursuit and optokinetic slow phases, decreased vestibulo-ocular reflex gain, and impaired visual-vestibular interaction. This pattern corresponds to the known pathologic changes of Friedreich's ataxia and can be useful in the differential diagnosis of cerebellar atrophy.

Adolescent↗
PubMed1983

The Community Project: the teaching implications of applied epidemiology.

The use of the epidemiological method in primary health care (PHC) has become an accepted part of the service. The team will utilize community-oriented data in order to assess the health needs of the population, perform continued surveillance of changes in the health of the people served and for service evaluation. This development in health services has to find its counterpart in the training programme for the future doctor. This paper describes a 6-year experience with a community project carried out in the framework of a clinical clerkship in Family and Community Medicine. The students were able to define the project, collect the data and analyse it, and frequently see the start of the implementation of the recommendations.

Clinical Clerkship↗
PubMed1983

Transfusion-acquired Plasmodium malariae infection in two premature infants.

Several diseases can be transmitted to infants via transfusion. The risk of acquiring an infection via transfusion is greatly increased in sick premature infants because they receive frequent transfusions. The full-term infant is not fully competent immunologically, and the premature infant is even less able to deal with infection. Ideally, the transfusion of infected blood, especially into immunoincompetent recipients, should not occur. However, because screening for malaria in nonendemic regions is not practical, physicians caring for sick premature babies should consider transfusion-acquired malaria as a possible cause of illness, especially when there is no response to antibacterial therapy.

Blood Donors↗
PubMed1981

High-performance liquid chromatographic analyses of the antihypertensive drug captopril.

High-performance liquid chromatographic systems have been developed to separate and quantitate captopril. The presence of interfering excipients in various formulations necessitated the development of three assays, each with distinctly different columns and mobile phases. All work well for bulk material, providing short analysis time, high precision, and rapid sample preparation, demonstrating that there is not necessarily one, best, high-performance liquid chromatographic system. The advantages and shortcomings of the ion-exchange, amino and octadecylsilane systems are evaluated and one of them is selected as optimum for bulk and tablet analysis.

Captopril↗
PubMed1980

Isolation of Leptospira biflexa from commercially prepared deionized water labeled "sterile for tissue culture".

Leptospira biflexa were isolated from urine cultures of two patients with clinical and laboratory findings compatible with leptospirosis. Neither patient had detectable leptospiral agglutinins. The source of the L. biflexa was water labeled " "sterile for tissue culture" purchased from M. A. Bioproducts, formerly Microbological Associates. M. A. Bioproducts water is sterilized by filtration through a 0.22-mum-pore size membrane filter. Leptospiral contamination can occur in products sterilized by filtration. Heat sterilization of water eliminates this possibility.

Adult↗
PubMed1980

Preclinical diagnosis and carrier detection in ataxia associated with abnormalities of lipoamide dehydrogenase.

To see whether kinetic assays of lipoamide dehydrogenase could be used for carrier detection or preclinical diagnosis, Michaelis-Menten constants (KmL and KmH) for the enzyme were determined in platelets from families with a form of recessive Friedreich ataxia and low activities of the enzyme. The KmL of patients' enzyme was 132 +/- 5 microM lipoamide (mean +/- SEM) versus 56 +/- 9 microM for controls (p less than 0.001), and KmH for the patients was 421 +/- 19 microM versus 147 +/- 14 microM for the controls (p less than 0.001). The activity and Km values of one patient's enzyme were abnormal 1 year before neurologic signs appeared. The Km values for the enzymes of the six parents were also elevated (average KmL, 105 +/- 10 microM; average KmH, 378 +/- 47 microM, p less than 0.02). The maximal activities of the parents' enzymes, relative to a mitochondrial marker, were intermediate between the mean maximal control activity and the mean activity for the affected offspring. The data suggest that the abnormalities of lipoamide dehydrogenase are inherited in a recessive pattern in these families.

Adolescent↗
PubMed1976

A study of foldback DNA.

Nuclear DNA from eucaryotes contains a significant fraction which forms duplexes very rapidly and also independently of the DNA concentration. This fraction can be isolated by adsorption to hydroxylapatite and has been called foldback DNA (Britten and Smith, 1970). Here we extend previous studies to show that the foldback fraction is due to the existence of a finite number of foldback foci in each genome equivalent of DNA, approximately 10(5) in the case of Xenopus laevis. More significantly, we have isolated the foldback fraction in quantity from DNA of such a size (in one case broken randomly and in another digested with a restriction endonuclease) that only about 10% of the total DNA has foldback properties. If the foldback foci were located in precisely the same positions in all sets of the Xenopus laevis genome, the prediction would be that these foldback fractions would contain sequences representing 20% (random shear) and 10% (restriction endonuclease) of the total genome. In contrast, our results show that in both cases the foldback fraction contains the entire Xenopus laevis DNA sequence. One possible explanation of these observations is that as in procaryotes, eucaryotic DNA is randomly cross-linked. We show that cross-linkage of Xenopus laevis DNA is not sufficient to explain our observations. In consequence, we have adopted the hypothesis that the formation of foldback DNA is mainly an intrastrand phenomenon, but nevertheless occurs at different sites in different sets of the Xenopus laevis genome.

Animals↗
PubMed1975

DNA-RNA hybridization.

Interest in nucleic acid hybridization stems mainly from its great power as a tool in biological research. It is used in several quite distinct ways. Because of the high degree of specificity that they show, hybridization techniques can be used to measure the amount of one specific sequence within a very heterogeneous mixture of sequences. Measurements of 1/10(6)-10(7) have been recorded. In extension of this, various properties of a specific sequence can often be studied. Secondly, because the kinetics of nucleic acid hybridization are quite well understood, it can be used to characterize both a pure sequence and a very complex mixture of sequences, like the genome of a vertebrate. Thirdly, again because of its specificity, it can be used to measure homologies between different populations of nucleic acids. Lastly, in conjunction with other techniques, it can be used as a basis for the fractionation of nucleic acid populations and the purification of specific sequences. Specific examples of these applications are given, with special reference to the organization of the genome in higher eukaryotes.

Animals↗
PubMed1973

Mitochondrial protein synthesis: RNA with the properties of Eukaryotic messenger RNA.

A heterogeneous RNA fraction with properties resembling those of messenger RNA was identified in mammalian mitochondria. Synthesis of contaminating RNA of nuclear origin was suppressed by treatment with camptothecin. Labeling of the messenger-like RNA is completely inhibited by ethidium bromide, a specific inhibitor of mitochondrial functions.Although mitochondrial protein synthesis resembles that of prokaryotes in several regards, the messenger-like RNA is covalently linked to poly(adenylic acid) [poly(A)]. Poly(A) has thus far been found only in eukaryotic cells. The poly(A) segment has a gel electrophoretic mobility of about 4 S, corresponding to a length of 50-80 nucleotides, and thus resembles in size the poly(A) found in some mammalian viral RNAs. The messenger RNA can be released from the mitochondrial protein-synthesizing structure by treatment with puromycin.

Adenine↗