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Biomedical subjects

M C Harris

Publications and source records attributed to M C Harris.

At least 73 records · Page 4Linked to original sources
PubMed1983

Diminished bactericidal capacity for group B streptococci of neutrophils from children with chronic granulomatous disease.

The bactericidal capacity of neutrophils from healthy adults, male children with chronic granulomatous disease, and obligate heterozygote mothers for type Ic group B streptococci was assessed, using a fluorochrome microassay. Neutrophils from patients with chronic granulomatous disease had impaired bactericidal capacity for group B streptococci when compared with adults (P less than 0.01). Carriers demonstrated intermediate killing capacity.

Adult↗
PubMed1983

Release of oxytocin into blood and cerebrospinal fluid by electrical stimulation of the hypothalamus or neural lobe in the rat.

Oxytocin (OT) was measured in blood and cerebrospinal fluid (CSF) samples obtained from anaesthetized rats. Release of OT was evoked by electrical stimulation (15 s) of the hypothalamus or the neural lobe. Stimulation of the neural lobe increased plasma OT sevenfold without altering CSF levels. Hypothalamic stimulation released OT into both blood and CSF, although the rise in CSF was both delayed and prolonged compared to that in plasma. Stimulation sites which released OT into CSF extended over a large medial area of the hypothalamus. More lateral stimulation sites were much less effective. Our results show that the release of OT into blood and CSF can be dissociated and that CSF levels reflect the activity of those hypothalamic OT-neurones which do not project to the neural lobe.

Animals↗
PubMed1983

Phagocytosis of group B streptococcus by neutrophils from newborn infants.

The purpose of this study was to investigate the effect of severe "stress" on neonatal neutrophil (PMN) phagocytosis, and to compare the ability of neonatal and adult PMNs to ingest [3H]-labeled type Ic group B streptococcus (GBS). Three patient populations were studied: healthy and "stressed" newborn infants and healthy adults. Severe "stress" was defined as an acute, noninfectious respiratory illness, sepsis or severe birth asphyxia; 94% of these infants required assisted ventilation. Radiolabeled GBS was opsonized with 5% adult serum, and incubated with PMN monolayers adherent to glass coverslips. Bacterial uptake was determined at 0, 40, 60, and 80 min and expressed as counts per min/10(6) PMNs. Neutrophils from healthy and "stressed" newborn infants demonstrated a significant increase in bacterial uptake with time. Adult controls also showed a significant increase in phagocytosis through 60 min, but not during the 60--80 min time period. PMNs from "stressed" and healthy infants demonstrated enhanced bacterial uptake when compared to adults at 40, 60, and 80 min. There were no significant differences in bacterial ingestion between "stressed" and healthy infants. Radiolabeled GBS uptake did not correlate with birth weight, study age, Apgar scores, or peripheral leukocyte count for the "stressed" newborn population. Neutrophils from healthy and "stressed" newborn infants thus demonstrate increased phagocytosis of GBS when compared to healthy adults.

Adult↗
PubMed1981

Induction of gentamicin resistance by visible light.

Recent studies have demonstrated the ability of visible light or phototherapy to modify the intracellular DNA of prokaryotic and eukaryotic cells. The present study was undertaken to determine the effect of light used in phototherapy on antibiotic resistance in prokaryotic cells using tester strains of gentamicin-sensitive Escherichia coli and Staphylococcus aureus. A growing population of the tester microorganisms was inoculated on plates containing nutrient medium and gentamicin. Experiments were performed to determine the effect of blue light on the induction of gentamicin-resistant mutants. The plates were divided into two populations, one of which was illuminated, while the other was kept in the dark to serve as a control. During photoirradiation, the plates were protected from direct sunlight and air coded to maintain a temperature of 27 degrees C. The sample distance from the light source was adjusted to maintain a fluence rate (450 nm) of 141 uW/cm2. Control experiments were performed to investigate the effect of photoirradiation on the media and gentamicin. An increased frequency of mutation to gentamicin resistance was seen in the irradiated population of bacteria. The mutagenic effect was observed over a wide range of gentamicin concentrations and correlated in a linear fashion with increasing duration of photoirradiation. There was an inverse correlation between the size of the bacterial inoculum and the recovery of mutant bacteria.

Bacteria↗
PubMed1981

Plexiform neurofibroma: a case presentation.

A case of plexiform neurofibroma involving the foot has been reported. The literature is replete with cases involving other areas of the body (5-7, 9, 12-16). The immediate clinical problem associated with a plexiform neurofibroma is dependent upon its location. This case displayed no apparent systemic involvement except café au lait spots near the mass. The anatomical disruption and course along the posterior tibial nerve were remarkable. A plexiform neurofibroma of the foot is best treated by surgical excision because of its possible malignant transformation, its progressive nature, and the somatic problems that may result from disruption of normal anatomy.

Child↗
PubMed1979

Effects of chemoreceptor and baroreceptor stimulation on the discharge of hypothalamic supraoptic neurones in rats.

Experiments have been performed to examine the effects of activating the carotid body chemoreceptors and the arterial baroreceptors on the discharge of neurones within the hypothalamic supraoptic nucleus of the rat. Chemoreceptors were activated by intracarotid injection of 0.9% NaCl solution equilibrated with 100% CO2. The baroreceptors of the carotid sinus and aortic arch were activated by raising the blood pressure with an intravenous injection of phenylephrine. Chemoreceptor stimulation activated and baroreceptor stimulation inhibited the discharge of all the phasically discharging neurones tested. Neither stimulus had any consistent effect on non-phasically discharging neurones, although slight inhibition occasionally occurred. Anaesthesia of the carotid bifurcation abolished the effects of cardiovascular stimulation on the supraoptic neurones. Responses resumed when the anaesthesia wore off. However, the anaesthesia also seemed to alter the phasic pattern of discharge. The results are discussed with reference to the influence of the cardiovascular receptors upon the neurones in the supraoptic nucleus, and with reference to possible roles for the cardiovascular reflexes in control of vasopressin secretion.

Action Potentials↗
PubMed1978

Effects of microiontophoretic and intravenous application of gonadotrophic hormones on the discharge of medial-basal hypothalamic neurones in rats.

In ovariectomized rats, the responses of medial-basal hypothalamic neurones to gonadotrophic hormones have been recorded. The luteinizing and follicle stimulating hormones (LH and FSH) were applied to neurones both by microiontophoresis and by intravenous injection. Although LH was the more frequently effective, both hormones caused either excitation or inhibition of neurones, and the effects were consistently repeatable on the same neurones. Iontophoretic and intravenous application of the same hormones to the same neurone gave identical responses. Responsive neurones were found throughout the medial-basal hypothalamus and hormones were effective both on neurones which could be antidromically activated from the median eminence and on those which could not be activated. Treatment of rats with oestradiol, either during the experiment or 24 h earlier, did not significantly alter neuronal responses to the gonadotrophins. The results are discussed in terms of possible feedback by gonadotrophic hormones on the brain and it is suggested that such a feedback may not be concerned with control of gonadotrophic hormone secretion.

Action Potentials↗
PubMed1977

Feeding of school children in a London borough.

A survey of 12 schools in a London borough showed that the protein and energy content of the average school meal was below the standard set by the Department of Health and Social Security for all age groups. Failure to meet the standards resulted from inadequate food purchases, poor menu planning and portion control, and several management problems. A 24-hour recall questionnaire showed that 5% of the pupils were "poorly" fed. These pupils were, however, no worse off than their "adequately" fed peers with regard to absences from school or academic attainment measured by reading quotient, but there was some slight difference in height and weight. The percentage of children having no breakfast increased from 4% in the infant schools to 21% in the senior schools. Two per cent of the senior pupils regularly ate no lunch.

Adolescent↗