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Biomedical subjects

M D Smith

Publications and source records attributed to M D Smith.

At least 505 records · Page 28Linked to original sources
PubMed1982

Conidiogenesis in Petriellidium boydii (Pseudallescheria boydii). A light and electron microscope study.

Slide cultures of the type strain of P. boydii Shear, showed percurrent production of conidia by light microscopy over a period of several hours. Scanning and transmission electron microscopy were used to examine the conidiogenesis. The conidiogenous cells developed annular ridges rather than typical annellophoric scars. Evidence that these ridges represented sequential spore production was shown by T.E.M. in the form of a discontinuity of the outer conidiophore wall at the widest point of each ridge.

Ascomycota↗
PubMed1982

Peripheral blood lymphocytes in sarcoidosis.

Sarcoidosis is characterised by changes in the lymphocyte subpopulations of the peripheral venous blood in the majority of patients. Thymus derived lymphocytes (T cells) are low whilst Bursa derived lymphocytes (B cells) are usually normal in number. The T cell lymphopaenia is best regarded as a "switching off" of available receptors as in vitro treatment with Levamisole restores this population to normal control values. A functional subset of T cells, T suppressor cells (T gamma) are activated, in sarcoidosis, in peripheral venous blood. Sarcoid sera is characterised by two inhibiting fractions; one, of low molecular weight (60 000 daltons) inhibits E rosette formation by normal T lymphocytes and may be a product of T suppressor cells or epithelioid/macrophage cells: the other is an immune complex which is capable of activating normal T suppressor cells and the serum immune complex concentration is positively correlated with suppressor cell activation in sarcoidosis.

Adolescent↗
PubMed1982

The virtuous organization.

In this essay, I shall assume that at least some groups are moral agents, a view successfully argued for by Peter French (1972, 1979, 1981). To that view I add only the following two refinements: (a) The reality of group or organizational agents depends on the existence of rules that constitute them. Because a moral agent acts in a community of moral agents, it is important that the rules that give a group agent its identity be accepted not only by persons in the group but also by the persons and groups with which that group can reasonably be expected to interact. (b) The rule structure of groups provides a basis for claims about the (in)-voluntariness of group action. This is especially important in moral contexts. My primary concern in the essay will be to lay a conceptual foundation for certain normative questions about group moral agency. The questions with which I shall be concerned have to do most directly with the structure of the organization itself and only indirectly with its interactions with others.

Ethics↗
PubMed1982

Combined hepatotoxicity and neurotoxicity following sulphasalazine administration.

Two cases of hepatotoxicity following sulphasalazine administration are reported. Each patient became ill after her initial exposure to sulphasalazine and after being re-exposed to the drug. In both instances there was an interval of three weeks between receiving the drug for the first time and the onset of the toxic reaction. In the first patient, hepatotoxicity occurred after initial exposure and following the second course of sulphasalazine. Mild neurotoxicity was seen following second exposure to sulphasalazine. In the second patient, hepatotoxicity occurred following the initial exposure to sulphasalazine but after reexposure the only abnormality in liver function tests present was a slight rise in the serum level of gamma glutamyl transpeptidase. In this patient, life-threatening neurotoxicity occurred each time that the patient received sulphasalazine.

Adult↗
PubMed1982

Interaction of immune complexes and T suppressor cells in sarcoidosis.

Circulating immune complexes were present in half of 31 patients with sarcoidosis and raised levels were associated with low numbers of T suppressor cells (T gamma- and Fc gamma-receptor-positive lymphocytes). Incubation of T cells with trypsin restored the percentage of T gamma cells to within or above the normal range. Incubation of normal lymphocytes with sarcoid immune complexes significantly reduced the number of detectable T gamma cells. Preincubation of normal lymphocytes with circulating immune complexes significantly reduced their blastogenic response to concanavalin A. These studies suggest an interaction between immune complexes and T suppressor cells in sarcoidosis and emphasise the importance of immune complexes in modulating the immune response.

Adult↗
PubMed1981

High-performance liquid chromatographic determination of sodium nitroprusside.

A rapid high-performance liquid chromatographic method for the determination of nitroprusside in commercial lyophilized products or in intravenous admixture solutions is described. The method is stability-indicating. Reversed-phase liquid chromatography was performed using a microparticulate (10 micrometer) phenyl column with a mobile phase acetonitrile--phosphate/tetrabutylammonium hydroxide buffer (pH 7.1) (30:70) and detection at 210 nm. A coefficient of variation of less than 3.1% was achieved over the concentration range studied (10--50 microgram/ml). Total analysis time was 9 min. This method was used to show that there is a small loss of nitroprusside due to photodegradation during intravenous infusion, even when the admixture container is wrapped in foil as recommended and used expeditiously.

Chromatography, High Pressure Liquid↗
PubMed1981

Prostaglandin E and F concentrations in placentae of normal, hypertensive and pre-eclamptic patients.

The prostaglandins E and F were measured by radioimmunoassay in placentae from 23 normotensive, 25 hypertensive and 13 pre-eclamptic patients. The prostaglandin E levels were respectively (pg/mg +/- SEM) 16.34 +/- 2.06, 16.75 +/- 2.52 and 12.10 +/- 3.63. The prostaglandin F levels were 2.43 +/- 0.41, 2.70 +/- 0.42 and 2.06 +/- 0.31. These prostaglandin concentrations did not differ significantly. Local ischaemia may, therefore, be explained by altered responsiveness to these prostaglandins or to changes in other prostaglandins (such as the vasodilator PGI2) or other vasoactive agents.

Adolescent↗
PubMed1981

Homology among tet determinants in conjugative elements of streptococci.

A mutation to tetracycline sensitivity in a resistant strain of Streptococcus pneumoniae was shown by several criteria to be due to a point mutation in the conjugative omega (cat-tet) element found in the chromosomes of strains derived from BM6001, a clinical strain resistant to tetracycline and chloramphenicol. Strains carrying the mutation were transformed back to tetracycline resistance with the high efficiency of a point marker by donor deoxyribonucleic acids from its ancestral strain and from nine other clinical isolates of pneumococcus and by deoxyribonucleic acids from group D Streptococcus faecalis and group B Streptococcus agalactiae strains that also carry conjugative tet elements in their chromosomes. It was not transformed to resistance by tet plasmid deoxyribonucleic acids from either gram-negative or gram-positive species, except for one that carried transposon Tn916, the conjugative tet element present in the chromosomes of some S. faecalis strains. The results showed that the tet determinants in conjugative elements of several streptococcal species share a high degree of deoxyribonucleic acid sequence homology and suggested that they differ from other tet genes.

Base Sequence↗
PubMed1980

Rapid method for determination of riboflavin in urine by high-performance liquid chromatography.

A simple, specific, and sensitive high-performance liquid chromatographic (HPLC) method for the determination of riboflavin directly in urine samples using a fixed-wave-length spectrofluorometer is described. Centrifuged raw urine samples (50 microliter) are injected onto a reversed-phase microparticulate C18 column. The eluent is 0.01 M KH2PO4 (pH 5.0)-methanol (65:35). This method is capable of differentiating riboflavin from riboflavin-5-phosphate, non-riboflavin fluorescing components in urine, and photo-degraded riboflavin. The method shows good reproducibility and is linear to at least 12 micrograms/ml. The sensitivity of this procedure, at the 95% confidence limit, determined by linear regression analysis, is estimated to be 0.05 micrograms/ml using peak height and 0.07 micrograms/ml using peak area. This HPLC method is compared to an automated fluorometric method for riboflavin. The coefficient of linear regression of this comparison is Y = 0.858 + 0.893X, where X is the HPLC method and Y is the fluorometric method.

Chromatography, High Pressure Liquid↗
PubMed1980

Familial Mediterranean fever in Australia.

A case of familial Mediterranean fever is presented, which is, as far as it could be ascertained, the first reported case of this condition in Australia. The difficulties encountered in making this diagnosis are discussed along with diagnostic criteria necessary to substantiate a diagnosis of familial Mediterranean fever. The importance of this condition both to physicians and to surgeons is emphasized.

Aged↗
PubMed1980

Kinetic study of USP blue tetrazolium assay with methylprednisolone, hydrocortisone, and their hemisuccinate esters by high-pressure liquid chromatography.

The reactions of blue tetrazolium (I) with methylprednisolone and hydrocortisone and their hemisuccinate esters at ambient temperature under USP assay conditions in alcohol USP and in absolute alcohol were followed by high-pressure liquid chromatography (HPLC) and spectrophotometry. The disappearance of the ester and the increase and then decrease in the alcohol, as well as the formation of several reaction products with time, were observed by HPLC analysis. The reduction of I was observed spectrophotometrically. A sequential kinetic model was used to describe the overall reaction. The rate constants for the hydrolysis of the hemiester (k1), the reaction with I (k2), and the degradation of the parent steroid (k3) were determined by discrete kinetic experiments using HPLC. The following observations were made: (a) k1 is proportional to [H2O] and is the rate-limiting step, (b) k2 is about 100 times the value of k3 and (c) k2 for methylprednisolone is about the same as for hydrocortisone and appears to be independent of the concentration of water. With these rate constants, simulated time-concentration profiles for the reaction of the esters with I favorable compared with experimental data in alcohol USP and absolute alcohol. This study shows that the USP blue tetrazolium assay with these esters has potential for variability and is not stability indicating.

Chemical Phenomena↗
PubMed1980

Cryptosporidiosis in man: parasite life cycle and fine structural pathology.

The Cryptosporidium here described is a very small (3-4 micron) opportunistic pathogenic coccidian parasite. Through seven known human enteric infections it is now associated with diarrhoea in immunosuppressed or immunodeficient individuals. Neither the full pathogenic potential nor the complete life cycle of this parasite are known, and there is no adequate chemotherapeutic agent with which to eradicate it. What is known of its intracellular intestinal forms and the fine structural changes occurring in parasitised epithelial cells has been described. A viral complication of the infection is discussed and mention is made of relevant cryptosporidial infections of domestic and other animals.

Adenovirus Infections, Human↗