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Biomedical subjects

N Smith

Publications and source records attributed to N Smith.

At least 217 records · Page 12Linked to original sources
PubMed1980

Studies on choline ad ethanolamine phosphoglyceride biosynthesis in developing rabbit brain.

Activities of cholinephosphotransferase (EC 2.7.8.2) and ethanolaminephosphotransferase (EC 2.7.8.1) were evaluated in microsomal preparations derived from rabbit cerebrum. Animals ranged in age from nineteen days' gestation through two months of postnatal development. Under optimal conditions the properties of these transferases in rabbit brain were remarkably similar relative to pH, divalent cation requirements, and apparent-Km values for the CDP-intermediates and the lipid acceptor, respectively. Cholinephosphotransferase-specific activity exhibited a dramatic rise during the last 15%-20% of fetal life and a second rise to a maximum near the 15th postnatal day. Ethanolaminephosphotransferase-specific activity exhibited a similar, but less striking age-related increase during the same period. Growth of rabbit cerebrum as determined by weight, increased 30-fold during this same period (24 days gestation to the 19th postnatal day). Specific activities of these transferase were similar in brain preparations from mid-fetal and early adult rabbits. The maximum specific activity of cholinephosphotransferase exceeded that of ethanolaminephosphotransferase by 3-4-fold. Age-related changes in the specific activities of these transferases appear to correlate with the developmental pattern of morphological and compositional events occurring in rabbit cerebrum during the last third of gestation and the first three weeks of postnatal life.

Age Factors↗
PubMed1980

Adherence of influenza A viruses to group B Streptococci.

Previous studies have revealed a similarity between hemadsorption and bacterial adherence to virus-infected cells. This observation led to the question of whether mature virions can interact directly with bacteria in a manner similar to hemagglutination. Thus, hemagglutination inhibition, direct immunofluorescence, and scanning electron microscopy were used to detect adherence of five prototype strains of influenza A virus to 34 strains (five serologic prototypes and 29 isolates from ill infants) of group B Streptococcus. Group B Streptococcus serotypes Ia, Ic, and III appear to possess receptors for the five influenza strains that are sensitive to receptor-destroying enzyme. The results of adherence tests with Streptococcus serotype Ib depended on which bacterial strain was used. Only one virus prototype, Jap/305/57(H2N2), adhered to all of the 34 strains of Streptococcus tested.

Hemadsorption↗
PubMed1980

Evaluation of staining methods of resin embedded cutaneous tissue sections of mycosis fungoides.

Biopsies from lesional skin of patients with histologically confirmed mycosis fungoides were embedded in resin and semi-thin ( I micrometer) sections were submitted to a variety of staining procedures, including Toluidine blue, Richardson's Huber, Giemsa, Paragon and Tribasic stains. The stained sections were examined with the light microscope and the quality of cellular morphological detail afforded by the different stains was assessed. The Toluidine blue, Richardson's and Paragon stains were found to be technically easy to perform and gave the best representation of nuclear and cytoplasmic detail Of these, the authors favoured Richardson's stain. The technique of processing the tissue, and staining a mounting procedures are detailed.

Adolescent↗
PubMed1979

Dysrhythmias in apparently healthy elderly subjects.

Using 24-hour ambulatory electrocardiographic (ECG) monitoring, the incidence of cardiac dysrhythmias was investigated in 50 apparently healthy elderly subjects aged over 60 years. There was a high incidence of both ventricular and supraventricular ectopic beats, supraventricular tachycardia and sinus arrest. First- and second-degree block were also noted. The incidence of dysrhythmias bore no obvious relationship to age over 60, sex, blood presssure, cigarette smoking, caffeine and theophylline ingestion or resting 12-lead ECG abnormalities.

Aged↗
PubMed1978

The 5-S RNA . protein complex from an extreme halophile, Halobacterium cutirubrum. Purification and characterization.

A 5-S RNA . protein complex has been isolated from the 50-S ribosomal subunit of an extreme halophile, Halobacterium cutirubrum. The 50-S ribosomal subunit from the extreme halophile requires 3.4 M K+ and 100 mM Mg2+ for stability. However, if the high K+ concentration is maintained but the Mg2+ concentration lowered to 0.3 mM, the 5-S RNA . protein complex is selectively extracted from the subunit. After being purified on an Agarose 0.5-m column the complex had a molecular weight of about 80000 and contained 5-S RNA and two proteins, HL13 and HL19, with molecular weights (by sedimentation equilibrium) of 18700 and 18000, respectively. No ATPase or GTPase activity could be detected in the 5-S RNA . protein complex. The amino acid composition and electrophoretic mobility on polyacrylamide gels indicated both proteins were much more acidic than the equivalent from Escherichia coli or Bacillus stearothermophilus. Partial amino acid sequence data suggest HL13 is homologous to EL18 and HL19 to EL5.

Adenosine Triphosphatases↗
PubMed1978

Antigens of human trophoblasts: a working hypothesis for their role in normal and abnormal pregnancies.

This report describes the preparation and characterization of antisera to human trophoblast membranes. Rabbit antisera were raised to trophoblast microvilli prepared by differential ultracentrifugation. Antibodies to serum proteins were removed by solid-phase immunoabsorption with normal human serum, and indirect immunofluorescence experiments with cryostat sections of human placentas showed that the absorbed anti-trophoblast sera reacted with trophoblasts as well as with stromal cells and endothelium of chorionic villi. The antisera also produced membrane fluorescence when studied on viable lymphocytes and certain human cell lines. These anti-trophoblast sera were also lymphocytotoxic, and this reaction was abolished by prior absorption of the antisera with leukocytes. The leukocyte-absorbed anti-trophoblast sera retained their ability to react with trophoblasts and certain human cell lines, but no longer reacted with lymphocytes or placental stromal cells and endothelium. Two categories of trophoblast membrane antigens are thus defined: one present on trophoblasts and certain human cells lines (tentatively designated TA(1)), and the other on trophoblasts and lymphocytes, villous fibroblasts, and endothelium (tentatively designated TA(2)). A working hypothesis is proposed stating that normal pregnancy involves the generation of anti-TA(2) subsequent to blastocyst implantation and entrance of trophoblasts into the maternal circulation. This involves a mechanism similar to allogeneic cell stimulation and results in antibodies that block either the recognition or cytotoxicity of TA(1). Failure to mount this response allows TA(1) recognition and trophoblast immunopathology. Experimental and clinical studies in support of this working hypothesis, particularly involving abortion and toxemia, are cited from published reports.

Cell Line↗
PubMed1978

Comparative evaluation of a modified zinc sulfate flotation technique.

A modified zinc sulfate flotation technique using Formalinized fecal specimens (F-ZnSO4) was compared to the Formalin-ether (FE) concentration method for the laboratory diagnosis of intestinal parasites. Many laboratories have difficulty storing, using, and disposing of either and need a procedure for concentrating fecal specimens which does not require ether. Comparative data were obtained for the recovery of protozoan cysts and helminth eggs and larvae from feces preserved in Formalin less than and longer than 1 month. Whereas the FE method was found generally to be more efficient, F-ZnSO4 was apparently more effective for the recovery of some species of parasites. F-ZnSO4 was not satisfactory for recovery of schistosome eggs. We conclude that, except for schistosomes, F-ZnSO4 compares favorably to the FE method for detecting infections of clinical significance.

Eukaryota↗
PubMed1978

Severe aortic stenosis with impaired left ventricular function and clinical heart failure: results of valve replacement.

Nineteen patients, aged 58-80 years, with severe isolated aortic valve stenosis, severely reduced ejection fraction and clinical heart failure underwent aortic valve replacement between January 1970 and April 1977. Ten had concomitant coronary artery disease (all underwent additional coronary bypass surgery), 17 had angina pectoris and four had syncope. Aortic valve area index was 0.32 +/- 0.03 cm2/m2 (mean +/- SEM); left ventricular (LV) end-diastolic volume index was 117 +/- 9 ml/m2 and LV ejection fraction was 0.37 +/- 0.02. There were four operative deaths and one late death. The follow-up time ranged from six to 74 months (38 +/- 6 months). Actuarially determined three-year survival is 74 +/- 10%; the expected five-year survival is the same. One patient had a serious cerebrovascular accident. Of the remaining survivors, seven were initially Functional Class IV and six Class III; currently, six are Class I and seven Class II (New York Heart Association classifications). The cardiothoracic ratio has decreased from 0.54 +/- 0.03 to 0.49 +/- 0.03. Repeat hemodynamic evaluation has been performed in 10 patients, 22 +/- 6 months after surgery. In these 10 patients, the aortic valve gradient decreased from 55 +/- 7 11 +/- 1.3 mm Hg; LV end-diastolic pressure from 22 +/- 2.4 to 9 +/- 1.9 mm Hg; LV end-diastolic volume index from 119 +/- 16 ml/m2 to 107 +/- 11 ml/m2. LV ejection fraction has increased dramatically from 0.34 +/- 0.03 to 0.63 +/- 0.05 and mean velocity of circumferential fiber shortening from 0.57 +/- 0.08 to 1.3 +/- 0.18 circ/sec. The encouraging long-term survival, improved functional class and the marked improvement in left ventricular function that occurred in our patients indicate that all patients with severe aortic stenosis in clinical heart failure should be offered aortic valve replacement.

Aged↗