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Biomedical subjects

J M Robinson

Publications and source records attributed to J M Robinson.

At least 181 records · Page 10Linked to original sources
PubMed1979

Relationship between lysostaphin endopeptidase production and cell wall composition in Staphylococcus staphylolyticus.

Mutants of Staphylococcus staphylolyticus incapable of producing an extracellular staphylolytic glycylglycine endopeptidase were isolated and found to have cells in the population susceptible to lysis by this enzyme, as did the wild-type organism under conditions in which the endopeptidase was not produced. These results suggest that cultures of this organism normally contain a heterogeneous population of cells with regard to cell wall composition and susceptibility to the enzyme. Production of the endopeptidase appears to act as a selective pressure which removes the susceptible cells in the population as the enzyme appears in the medium. A comparison of the peptidoglycan of the wild-type organism grown under conditions in which the endopeptidase was produced with that of this organism grown under nonproducing conditions and with those of endopeptidase-less mutants showed that in the presence of the endopeptidase the cell population had peptidoglycan with shorter peptide cross bridges and a greater percentage of serine in these cross bridges than was found in cells grown in the absence of the enzyme. The inability of the endopeptidase to hydrolyze glycylserine and serylglycine peptide bonds suggests that at least part of the resistance this organism has to the endopeptidase is due to relative amounts of serine found in the peptide cross bridges of some cells in the population.

Cell Wall↗
PubMed1979

Membrane alterations and other morphological features associated with polyethylene glycol-induced cell fusion.

Polyethylene glycol (PEG) induces rapid fusion of LM cells. Membrane fusion, as detected by formation of pentalaminar membrane arrays, occurs as early as 1 min after PEG treatment. The entire cell surface arrears to be capable of fusion since fusion occurs in regions where pseudopodia make contact with each other or with a neighbouring cell body and also in areas where cells are in contact along their entire periphery. Cytoskeletal components showed no apparent deleterious effect from PEG treatment or subsequent cell fusion as determined by thin-section EM. Freeze-fracture of monolayer cultures reveals a thermotropic rearrangement of intramembranous particles following PEG treatment.

Animals↗
PubMed1979

The eyes have it.

Explore the source record for details and available documents.

Dentists↗
PubMed1978

Medical screening of old people accepted for residential care.

Medical screening of 100 old people at the time of their acceptance for admission to residential (part 3) care revealed a great deal of previously unreported yet treatable illness. As a result of screening, alternative care was thought more appropriate in 32 cases--hospital admission in 16, sheltered housing in 4, and remaining at home in 12. It is therefore suggested that the time of translocation of an old person from independent to institutional living is a time when medical screening is particularly appropriate.

Aged↗
PubMed1978

Localization of D-amino acid oxidase on the cell surface of human polymorphonuclear leukocytes.

The ultrastructural localization of D-amino acid oxidase (DAO) was studied cytochemically by detecting sites of hydrogen peroxide production in human polymorphonuclear leukocytes (PMNs). Reaction product, which forms when cerous ions react with H2O2 to form an electron-dense precipitate, was demonstrated on the cell surface and within the phagosomes of phagocytically stimulated cells when D-amino acids were provided as substrate. Resting cells showed only slight activity. The competitive inhibitor D,L-2-hydroxybutyrate greatly reduced the D-amino acid-stimulated reaction while KCN did not. The cell surface reaction was abolished by nonpenetrating inhibitors of enzyme activity while that within the phagosome was not eliminated. Dense accumulations of reaction product were formed in cells which phagocytosed Staphylococcus aureus in the absence of exogenous substrate. No reaction product formed with Proteus vulgaris while an intermediate amount formed when Escherichia coli were phagocytosed. Variation in the amount of reaction product with the different bacteria correlated with the levels of D-amino acids in the bacterial cell walls which are available for the DAO of PMNs. An alternative approach utilizing ferricyanide as an electron acceptor was also used. This technique verified the results obtained with the cerium reaction, i.e., the DAO is located in the cell surface and is internalized during phagocytosis and is capable of H2O2 production within the phagosome. The present finding that DAO is localized on the cell surface further supports the concept that the plasma membrane is involved in peroxide formation in PMNs.

Cell Membrane↗
PubMed1977

Ergot alkaloids. Synthesis of 6-alkyl-8-ergolenes and 6-methyl-8-aminoergolines as potential prolactin inhibitors.

The synthesis of several N-6 derivatives of elymoclavine (3) and potential alkylating derivatives of 6-methyl-8-aminoergolines (12) is described. These compounds were screened for prolactin-inhibiting ability and 6-propyl-8-hydroxymethyl-8-ergolene (9) was found to be as active as the most potent prolactin inhibitors reported to date. The total synthesis of racemic methyl dihydrolysergate I (23), having a trans C, D ring fusion, from the tricyclic ketone 18 is also described.

Animals↗
PubMed1977

Influence of pH upon the Warburg Effect in Isolated Intact Spinach Chloroplasts: I. Carbon Dioxide Photoassimilation and Glycolate Synthesis.

The influence of pH upon the O(2) inhibition of (14)CO(2) photoassimilation (Warburg effect) was examined in intact spinach (Spinacia oleracea) chloroplasts. With conditions which favored the Warburg effect, i.e. rate-limiting CO(2) and 100% O(2), O(2) inhibition was greater at pH 8.4 to 8.5 than at pH 7.5 to 7.8. At pH 8.5, as compared with 7.8, there was an enhanced (14)C-labeling of glycolate, and a decrease of isotope in some phosphorylated Calvin cycle intermediates, particularly triose-phosphate. The (14)C-labeling of starch was also more inhibited by O(2) at higher pH. The enhanced synthesis of glycolate during (14)CO(2) assimilation at higher pH resulted in a diminution in the level of phosphorylated intermediates of the Calvin cycle, and this was apparently a causal factor of the increased severity of the Warburg effect.The (14)C-labeling profiles have been interpreted in terms of a "CO(2)"-sensitive as well as a "CO(2)"-insensitive mechanism for glycolate synthesis. Both mechanisms functioned optimally at the higher pH and both responded to O(2).

Journal Article↗
PubMed1977

Influence of pH upon the Warburg Effect in Isolated Intact Spinach Chloroplasts: II. Interdependency of Glycolate Synthesis upon pH and Calvin Cycle Intermediate Concentration in the Absence of Carbon Dioxide Photoassimilation.

The light-dependent synthesis of glycolate derived from fructose 1,6-diphosphate, ribose 5-phosphate, or glycerate 3-phosphate was studied in the intact spinach (Spinacia oleracea) chloroplasts in the absence of CO(2). Glycolate yield increased with an elevation of O(2), pH, and the concentration of the phosphorylated compound supplied. No pH optimum was observed as the pH was increased from 7.4 to 8.5. The average maximal rate of glycolate synthesis was 50 mumoles per milligram chlorophyll per hour while the highest rate observed was 92 with 2.5 mm fructose 1,6-diphosphate in 100% O(2). The highest yields of glycolate synthesized from fructose 1,6-diphosphate, ribose 5-phosphate, or glycerate 3-phosphate were 0.14, 0.24, and 0.30, respectively, on a molar basis.

Journal Article↗
PubMed1977

Electrolaryngography in laryngeal disorders.

This study was designed to analyse recordings of vocal fold vibrations using the laryngograph, a machine which measures the change in electrical impedance across the larynx. Recordings were made of each patient reading a standard text. The output was analysed in two ways: by study of waveform, and by production of a frequency distribution curve, this last being performed by a PDP 12 computer. Analysis shows an increase in the low frequencies and irregular curve associated with hoarseness but no pattern specific for different diseases. After operation and speech therapy an objective measure of success or failure is provided. But for practical use other than in research a less time consuming method of analysis is necessary. Production of this is being considered.

Humans↗
PubMed1976

Wound infection following laryngectomy. The effect of topical ampicillin and carbenicillin.

A study of twenty-two consecutive laryngectomies performed in one unit is reported. In eleven controls, seven (67%) developed a wound infection. In eleven patients, IG of Ampicillin and IG of Carbenicillin were used topically, and three (18%) developed a wound infection (P less than 0-04). Studies of the bacterial flora at the time of operation suggest that the major source of wound contamination is colonization of the upper gastrointestinal and respiratory tract. The ease with which a small innoculum of pathogens produces wound infection in these patients is discussed, and it is suggested that the underlying defect is depression of host cellular immunity resulting in failure of bacterial destruction by activated macrophages.

Administration, Topical↗
PubMed1976

Deep vein thrombosis in ear, nose and throat surgery.

I. One hundred and three patients undergoing head and neck or ear operations were screened for deep vein thrombosis using I125 labelled fibrinogen. 2. No thrombosis was detected in thirty-five patients undergoing ear operations. 3. Nine (16%) of fifty-six patients who underwent head and neck operations subsequently developed deep vein thrombosis. In a further twelve patients undergoing head and neck operations the ankle was used as a drip site and seven of these patients developed thrombosis in that leg.

Adult↗
PubMed1976

Pharyngeal symptoms caused by cervical osteophytes.

A case of cervical osteophytes producing the sensation of a 'lump in the throat' is described. This symptom was relieved by excision of the offending osteophytes. Emphasis is placed on the need for surgical correction before progression of degenerative disease makes the procedure technically impossible. Several points concerning the operative and postoperative management are made.

Adult↗
PubMed1976

Cytochemical localization of peroxidase activity in the mitochondria of Hymenolepis diminuta.

A cytochemical study of mitochondria of Hymenolepis diminuta indicates the presence of a mitochondrial peroxidase. Utilizing a 3,3'-diaminobenzidine (DAB) medium at pH 9.7, the reaction product is localized in the intracristal space, and between the inner and outer membranes of the mitochondria. No inhibitory effects are exerted on the peroxidase reaction by cyanide, azide, or aminotriazole. In addition, the mitochondria appear to have an enzyme which is cytochemically similar to vertebrate cytochrome c-oxidase. The possible physiological significance of the peroxidase is discussed.

Animals↗
PubMed1976

Familial bleeding tendency and tonsillectomy.

A retrospective study of 2,292 tonsillectomies revealed 12 cases of hereditary capillary fragility. These cases showed an increased morbidity from bleeding complications and accounted for 4.8 per cent of those with a secondary hemorrhage. When diagnosed, skin bleeding time should be carried out at the time of premedication, and, if prolonged, the procedure postponed.

Adult↗