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Biomedical subjects

M Harris

Publications and source records attributed to M Harris.

At least 613 records · Page 34Linked to original sources
PubMed1983

Survival and outcome of infants 501 to 750 gm: a six-year experience.

We investigated the outcome of 60 infants with birth weight 501 to 750 gm, admitted to our neonatal intensive care unit over six years. Twenty-five infants were inborn and 35 outborn. Twenty-eight survived 28 days or longer (47%), and 24 were discharged (40%). The infants who died had a significantly increased incidence of intracranial hemorrhage, and their mothers had a significantly decreased use of tocolytic drugs and betamethasone. Of the 24 survivors, two died after discharge, leaving 22 long-term survivors. Of these, 18 (82%) were observed until 20 months to 7 years of age. Mean height and weight were near the fifth percentile until 3 years of age, then increased to the tenth to fiftieth percentiles between 4 and 6 years. Mean head circumferences always remained between the tenth and fiftieth percentiles. Mean IQ was 100.0 +/- 17.9 for the inborn and 87.2 +/- 15.1 for the outborn infants (excluding two whose IQ was less than 50). Two infants (11%) had neurologic sequelae, 12 (67%) were completely normal, and four (22%) were functional and of borderline or below average intelligence. No statistical differences were found between the inborn and outborn children. This study indicates that, with aggressive therapy, outcome of the infant with birth weight 501 to 750 gm is much improved.

Critical Care↗
PubMed1983

The association of cytosol oestrogen and progesterone receptors with histological features of breast cancer and early recurrence of disease.

Two hundred and eighty-eight primary breast tumours were examined for the presence or absence of oestrogen (REc) and progesterone (RPc) receptors. Analysis has shown a relative interdependence between the steroid receptor status of primary breast cancer and other prognostic variables such as histological grade, lymphocytic infiltration and tumour elastosis. There were significant associations between epithelial cellularity, stromal fibrosis and the value of REc in those tumours in which the receptor was present. Cellularity and fibrosis were unrelated to the presence or absence of oestrogen receptor. By contrast, neither the presence or absence nor the value of RPc could be related to cellularity or fibrosis. The value of REc and RPc analysis as an indicator of prognosis was examined in a sub-group of 175 patients receiving no additional treatment following mastectomy. Overall relapse-free survival (RFS) was no different for those patients with receptors compared to those without them (REc P = 0.11, RPc P = 0.7). There was no difference in RFS of receptor positive and negative tumours when the axillary node status was taken into account.

Age Factors↗
PubMed1983

Pediatric practice in physical therapy. A survey.

This study was undertaken to define the role and functions of the physical therapist in pediatrics, specifically at the advanced clinical competence level. Questionnaires mailed to all members of the Section on Pediatrics of the American Physical Therapy Association were used to collect the data reported here. Of 109 consultative, evaluation, treatment planning, and implementation tasks, 37 were not considered important to the practice of physical therapy in pediatrics. Of the 72 tasks identified as important, 46 were at entry level and 10 at the advanced level. Sixteen tasks were not clearly defined. This initial survey provides useful data to begin to interpret the physical therapist's role in pediatrics. Validation studies are needed to verify that the identified advanced level responsibilities represent skills necessary for practice in pediatrics at the advanced competence level.

Child↗
PubMed1983

Clinical comparison of glucose broth with nutrient broth blood cultures for the detection of "Streptococcus viridans" bacteraemia.

Viridans streptococci were isolated from the blood stream of half of 50 patients undergoing dental extractions approx. 2 min before blood culture. Glucose and nutrient broths were tested in parallel. There was no significant difference between the isolation rates of streptococci by the two methods after incubation for 7 days, nor did the addition of glucose 0.1% to nutrient broth significantly increase the speed of detection of streptococci; the isolation rates of streptococci during the first 48 h of incubation were similar with both types of broth. Although there were a few more isolations of streptococci from the glucose broth than from the nutrient broth during the first 20 h, the difference was not statistically significant. No rapid lethal effect against streptococci was observed in glucose broth during incubation for 7 days. These results suggest that adding glucose 0.1% to nutrient broth for blood culture does not influence the recovery of organisms from patients with "Streptococcus viridans" bacteraemia after incubation of the broth for 2-7 days.

Culture Media↗
PubMed1983

Antigen-specific, major histocompatibility complex-restricted T cell receptors.

In this paper we have summarized our work on the structure of the receptor for Ag/MHC on 3 T cell hybridomas. In each case, these receptors have been identified by their reaction with antibodies, thought to be directed against Ag/MHC receptors because of their clone-specificity, and their ability to interfere with Ag/MHC recognition by the relevant hybridoma. The antibodies precipitate approximately 85 kd molecular weight heterodimeric glycoproteins from these cells. These reduce to 2 chains of 40-43 kd, one of acidic and the other of basic pI. These bulk characteristics apply to receptors from Class II-restricted, as well as Class I-specific T cells. There is evidence of molecular weight heterogeneity for both alpha and beta-chains in the mouse, both having 40 and 43 kd forms. Isoelectric focussing patterns suggest that both chains vary in amino acid sequence between clones. Peptide maps show that the receptor varies in amino acid sequence between clones, but that some peptides appear common, i.e., the receptor seems to have both variable and constant amino acid sequences. It is even possible that allotypic differences between the peptide maps of BALB/c and C57BL/6-derived receptors have been identified, though more data will be needed to confirm this. Finally we have recently shown that reaction with an anti-idiotype predicts both the Ag and MHC specificity of the T cell hybridoma bearing it, suggesting that a single receptor, responsible for binding both Ag and MHC, is identified by the anti-idiotypic antibody. The similarities between these T cell-bourne molecules, and immunoglobulin are inescapable. Both are disulphide-linked glycoproteins made up of 2 chains, both of which may vary in amino acid sequence. Secreted immunoglobulin is, of course, polyvalent, being composed of two or more of each type of chain, this contributes to the efficiency with which the molecule can bind polyvalent antigen or build precipitable lattices. Similar constraints do not apply to T cell-bound receptors, which do not seem to have a secreted form.

Animals↗
PubMed1983

The nature of the amyloid-like material in a calcifying epithelial odontogenic tumour: an ultrastructural study.

An ultrastructural study was carried out to investigate the nature of an eosinophilic material, having the staining properties of amyloid, in a case of calcifying epithelial odontogenic tumour. At the electron-microscopical level, the eosinophilic masses consisted of two types of structure which are probably related. The first type appeared as sheets of fine filaments measuring 10-12 nm in diameter. The second type was in the form of aggregates of lamina densa fragments, probably secreted by the tumour epithelium. These fragments appeared to undergo some loss of electron density and became degraded into fine filaments, having similar thickness and electron density to those forming the filamentous masses. It is concluded from this study that the fine filamentous material is a form of amyloid which results from degradation of lamina densa material.

Amyloid↗
PubMed1983

Redundancy of syntactic information: an aid to young children's comprehension of sentential number.

Sentences conveying either non-redundant or increasingly redundant information about number, by means of different syntactic markers, were presented to 20 nursery school children. Comprehension of each sentence was tested in two tasks: pointing to one of a pair of line drawings and acting out with toys the action described by a sentence. The results strongly supported the view that redundancy of syntactic information is a powerful aid to children's comprehension of sentential number. In a second experiment, comprehension of sentences conveying redundant information by repetition of the same number marker was compared with that of non-redundant sentences. In contrast to the first experiment, redundancy had no significant effect on comprehension. Together, these results suggest that children's comprehension of sentential number if aided by redundancy of information involving different syntactic markers, but not by mere repetition of the same marker.

Child, Preschool↗
PubMed1983

Properties of asparagine synthetase in asparagine-independent variants of Jensen rat sarcoma cells induced by 5-azacytidine.

Jensen rat sarcoma cells in culture require L-asparagine for growth and lack detectable levels of asparagine synthetase. Cultures exposed for 24 h to graded concentrations of 5-azacytidine give rise to asparagine-independent variants in high frequency. These prototrophs are stable phenotypically whether maintained in the presence or absence of L-asparagine. Asparagine synthetase activity in several variant clones was uniform in thermolability and several kinetic parameters, as well as in immunological properties. Parental Jensen rat sarcoma cells contained no detectable immunologically cross-reacting material. Our data suggest that transitions between asparagine dependence and independence in these cells are mediated by stable shifts in gene expression rather than by structural gene mutations.

Animals↗
PubMed1983

Macroglobulinaemia and intestinal lymphangiectasia: a rare association.

Two cases in which macroglobulinaemia was associated with intestinal lymphangiectasia are recorded. Immunoperoxidase stains demonstrated a high content of monoclonal IgM in the intestinal lymph. The seven previously recorded examples of this association are reviewed. It is concluded that the concurrence of these two conditions is not merely fortuitous, and that increased viscosity of the lymph consequent on its high IgM content may be important in the pathogenesis of the intestinal lymphangiectasia.

Aged↗
PubMed1983

Effect of heparin on the in vivo release and clearance of human platelet factor 4.

Intravenous injection of heparin (100 U/kg) into normal volunteers resulted in an increase of platelet factor 4 (PF4) level in platelet-poor plasma from a mean value of 18.1 +/- 6.6 ng/ml before the injection to 257.9 +/- 68.3 ng/ml at 5 min after injection. PF4 antigen isolated from "postheparin plasma" by adsorption on heparin-agarose and elution with 2.0 M NaCl and "authentic PF4" isolated from human platelets showed identical patterns of migration as determined by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Material released by washed human platelets was injected intravenously into rats. The clearance of PF4 followed a biphasic exponential pattern. The half-lives (T1/2) for the fast and slow components for control rats were 1.2 and 17.1 min. Heparin significantly extended the half-life of human PF4 in rat circulation. The clearance of PF4 injected together with heparin followed a single component model with a half-life of 27.6 min. Administration of heparin to rats that had been previously injected with human platelet releasate resulted in a 30-fold increase of plasma PF4 level in their circulation. The clearance of PF4 from the circulation of these rats (T1/2 = 45 min) fitted a single component model. We propose that PF4 is originally secreted by platelets into circulation and subsequently bound reversibly to vascular sites from which it can be released back into the circulation by heparin. The fast component of PF4 clearance that is abolished by heparin may reflect binding of this protein to the endothelial cells.

Animals↗
PubMed1982

Induction of thymidine kinase in enzyme-deficient Chinese hamster cells.

Previous work with Chinese hamster cells suggests that thymidine kinase deficiency and loss of potential for plating in HAT medium may arise by a process of mutation coupled with site-specific repression by bromodeoxyuridine at the tk locus. In this study, tk- Chinese hamster cells were exposed to a series of inductors to determine whether revertants for the putative second stage originate by genetic or epigenetic change. Brief exposure to 5-azacytidine resulted in massive conversion to the HAT+ state, and revertants showed levels of thymidine kinase activity intermediate between those of tk- and wild-type cells. By contrast, incidence of HAT+ cells rose only slightly in populations mutagenized with ethyl methanesulfonate. Large increases in frequency of HAT+ cells were obtained by treatment with n-butyrate and L-ethionine, which affect gene expression in other cell systems but have no known mutagenic potential. Induction of HAT+ revertants seems to be mediated by a stable epigenetic shift, which reverses the gradual extinction of thymidine kinase activity in the parent cells. The data support the view that induction in Chinese hamster cells results from changes in DNA methylation patterns, and suggests studies to define the process in molecular terms.

Animals↗
PubMed1982

Reduced bone growth in rats treated with anticonvulsant drugs: a type II pseudohypoparathyroidism?

The effect of anticonvulsant drugs on bone growth and calcium metabolism was studied in Wistar strain rats. Animals were treated for 40-48 days with diphenylhydantoin (DPH) or sodium valproate (SV), or were thyroparathyroidectomized (TPTX) and maintained with thyroxine supplements. Bone growth, measured radiographically as increase in bone length, was reduced by up to 12% in the drug-treated and TPTX groups. Plasma iPTH concentrations were raised twofold- to threefold by DPH and SV. Total plasma calcium was not significantly altered in the DPH-treated rats but was elevated by SV treatment. Similarly, elevated iPTH and normal calcium values were also found in carbamazepine-treated and diazepam-treated rats in a separate experiment. Plasma alkaline phosphatase was reduced by high doses of the drugs. These results imply that anticonvulsant drugs induce end-organ resistance to PTH (a feature of pseudohypoparathyroidism), which may be responsible for some of the skeletal and dental abnormalities found in patients treated with anticonvulsants.

Animals↗
PubMed1982

Spindle cell squamous carcinoma: ultrastructural observations.

Two spindle cell carcinomas of the skin and one of the breast have been studied by electron microscopy. In one tumour the spindle cells were of purely mesenchymal type and in the other two the spindle cells exhibited both mesenchymal and epithelial features within the same cells. The significance of the findings in relation to the histogenesis of the spindle cells is discussed, with special reference to the possible alternative roles of mesenchymal metaplasia of the epithelial component and spontaneous cell fusion between carcinoma cells and stromal cells.

Aged↗