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Biomedical subjects

R Carr

Publications and source records attributed to R Carr.

At least 73 records · Page 4Linked to original sources
PubMed1995

Impaired neutrophil phagocytosis in preterm neonates: lack of correlation with expression of immunoglobulin or complement receptors.

Preterm neonates are vulnerable to infection as a result of a compromised immune system. The function of neutrophils from 'well', 'stressed', and 'maturing' preterm neonates was compared with term neonate and adult neutrophils using a whole-blood phagocytosis assay. Cell surface expression of complement receptors and immunoglobulin G receptors was measured on neutrophils in whole blood from the same samples. Fewer actively phagocytosing neutrophils were found in all preterm neonate samples, especially in maturing neonates. Phagocytic rates were slower, and the number of Escherichia coli ingested was smaller in preterm neonate than in term neonate neutrophils. Expression of immunoglobulin G receptors and complement receptor 3 on neutrophils was not directly related to phagocytic activity.

Adult↗
PubMed1994

Stress management techniques: are they all equivalent, or do they have specific effects?

This article evaluates the hypothesis that various stress management techniques have specific effects. Studies comparing various techniques are reviewed, as well as previous literature reviews evaluating the effects of individual techniques. There is evidence that cognitively oriented methods have specific cognitive effects, that specific autonomic effects result from autonomically oriented methods, and that specific muscular effects are produced by muscularly oriented methods. Muscle relaxation and/or EMG biofeedback have greater muscular effects and smaller autonomic effects than finger temperature biofeedback and/or autogenic training. EMG biofeedback produces greater effects on particular muscular groups than progressive relaxation, and thermal biofeedback has greater finger temperature effects than autogenic training. Disorders with a predominant muscular component (e.g., tension headaches) are treated more effectively by muscularly oriented methods, while disorders in which autonomic dysfunction predominates (e.g., hypertension, migraine headaches) are more effectively treated by techniques with a strong autonomic component. Anxiety and phobias tend to be most effectively treated by methods with both strong cognitive and behavioral components.

Autogenic Training↗
PubMed1994

The effects of atropine on respiratory sinus arrhythmia in asthma.

Heart rate is rhythmically related to respiratory rate, in a phenomenon known as respiratory sinus arrhythmia (RSA). Amplitude of RSA has been found to be an accurate noninvasive measure of vagal tone in the normal population. The purpose of this study was to examine the relationship between RSA and cardiac vagal tone among asthmatics, a group which has been described as having elevated RSA. This was accomplished by examining the effects of atropine on RSA in asthmatics, and comparing the results to those obtained elsewhere among normal subjects. Atropine at a dose of 1 mg/75 kg body weight was administered to 18 asthmatics, and produced decreases in RSA, equivalent to those previously found among normal subjects. The results suggest that the relationship between cardiac vagal tone and RSA is unaffected by the presence of asthma.

Adolescent↗
PubMed1994

Effects of aerosol ipratropium bromide on cardiac vagal tone.

Thirty-one adult asthmatic subjects, aged 18 to 40 years, were administered both ipratropium bromide and placebo, in two sessions, held at least 2 days apart, in balanced order. Pulmonary function, heart period (milliseconds between heart beats), and respiratory sinus arrhythmia (a measure of cardiac vagal tone) were assessed before drug administration and 45 min thereafter. Ipratropium bromide had no significant effect on cardiac vagal tone, while it did produce improvement in pulmonary function.

Administration, Inhalation↗
PubMed1993

The Asthma Symptom Profile: a psychophysically based scale for assessment of asthma symptoms.

The Asthma Symptom Profile (ASP) assesses phasic changes in three dimensions of asthma symptoms: intensity, unpleasantness, and quality of sensations. Quantification data on verbal descriptors were gathered from 46 adult asthmatics for each of these scales, using bimodality scaling: i.e., with numerical estimates and drawing lines varying length. Close agreement was obtained between these two modalities. The ASP was analyzed before and after a bronchodilator in 44 asthmatics using ipratropium bromide (IB). Forty of these subjects were also tested in a placebo condition. Although ASP changes produced by IB were no greater than those produced by the placebo, correlations with changes in spirometry variables were significant. There were no significant differences in correlations with line drawings vs. numerical ratings. The ASP appears to be useful measure of phasic changes in asthma symptoms. Asthmatics with mild airway obstruction do not appear to be able to discriminate small changes in airway function.

Adolescent↗
PubMed1992

Malarial toxic antigens synergistically enhance insulin signalling.

Hypoglycaemia is a major complication of severe malaria [(1990) Trans. Roy. Soc. Trop. Med. 84 (suppl. 2) 1-65], especially cerebral malaria, in which it is associated with increased mortality [(1990) Lancet 336, 1039-1043; (1989) Quart. J. Med. (New series) 71, 441-459]; however, the mechanisms responsible have not been fully explained. Preparations containing toxic malaria antigens (TMA) released by blood stage Plasmodium yoelii malaria parasites have been shown to induce hypoglycaemia in mice lasting at least 8 h [(1992) Clin. Exp. Immunol. (in press)]. Here we report that TMAs can act synergistically with insulin in both stimulating lipogenesis and inhibiting lipolysis in rat adipocytes in vitro, and, furthermore, that they act synergistically with insulin in the induction of hypoglycaemia in vivo.

Adipose Tissue↗
PubMed1992

Endolymphatic delivery of IL2 in patients with melanoma and lymphoma.

UNLABELLED: During this phase I/II study, enodolymphatic cannulae were placed in the iliac lymphatics under general anaesthesia. IL2 was then infused via this route at escalating doses until the highest tolerated dose was achieved; then, continuous infusion was maintained for 2 to 3 weeks. Seven patients with advanced cancer (3 lymphoma, 4 melanoma), resistant to all other modalities of treatment received such therapy. Most patients tolerated 4 to 5 x 10(6) u/day of IL2 for 2 to 3 weeks with less toxicity as compared to the equivalent dosage given intravenously. No severe perioperative morbidity was experienced. One melanoma patient had a minor clinical response. Changes in circulating lymphocyte numbers and cytotoxicity demonstrated a systemic effect of endolymphatic IL2 therapy. CONCLUSIONS: The endolymphatic administration of IL2 is associated with less toxicity than the intravenous route but still achieves a systemic effect; a lower tumour burden may prove more responsive to this therapy.

Adult↗
PubMed1992

Neutrophil chemotaxis and adhesion in preterm babies.

To investigate the increased susceptibility to infection of very immature preterm neonates, neutrophil chemotaxis, Mac-1 adhesion receptor expression, and adherence to human umbilical vein endothelial cell monolayers (HUVE) were examined in neonates born at less than or equal to 32 weeks' gestation. Chemotaxis of neutrophils from well preterm neonates towards casein or zymosan activated serum (ZAS) was reduced (mean SE) being for casein 88.6 (3.8) microns; ZAS 76.2 (4.3) microns compared with adults (casein 117.8 (1.4) microns; ZAS 112.1 (1.4) microns), but similar to term neonate neutrophils (casein 92.7 (4.5) microns; ZAS 75.9 (3.1) microns). Stimulated Mac-1 expression showed a similar pattern: reduced on preterm neutrophils compared with adults, but similar to term neonates. Preterm and term neonate neutrophils were both hyperadherent to HUVE when unstimulated, but showed an equally impaired ability to increase adhesion following stimulation. Casein stimulated chemotaxis and stimulated Mac-1 expression 'matured' towards adult levels of performance four weeks after preterm birth. The increased incidence of sepsis in immature preterm infants is not due to greater defects of neutrophil migration.

Caseins↗
PubMed1992

Changes in plasma FcRIII demonstrate increasing receptor production during late pregnancy and after preterm birth.

We have previously described reduced expression of the Fc gamma receptor type III on the cell membrane (M-FcRIII) of neutrophils from very preterm neonates. To investigate the mechanism underlying this reduced receptor expression, we have measured neutrophil-derived soluble FcRIII (S-FcRIII) in the plasma of fetuses and neonates from 19 wk gestation. S-FcRIII in fetal plasma and in preterm neonates born before 32 wk gestation was consistently low [mean 13.6 +/- 1.2% (mean adult S-FcRIII = 100%, range 30-240%)]. In utero, S-FcRIII starts to rise from 33 wk and increases more than 4-fold to reach adult levels by term. S-FcRIII measured sequentially in preterm infants born as early as 24 wk of gestation showed a rapid postnatal increase to reach adult levels within 3 wk of birth. The changes in S-FcRIII paralleled changes in M-FcRIII expression on the cell surface. These observations point to a reduced rate of FcRIII production by fetal neutrophils as opposed to an increase in receptor release. The parallel increase in S-FcRIII and M-FcRIII suggests that there may be a programmed activation of FcRIII synthesis within individual cells late in the 3rd trimester of fetal development. In addition, FcRIII production may be switched on early by preterm birth.

Cell Membrane↗
PubMed1992

A comparison of photopic and scotopic electroretinographic changes in early diabetic retinopathy.

Previous studies of early diabetic retinopathy have shown that oscillatory potential (OP) amplitudes are reduced in many diabetic patients. OP amplitude is believed to be a more sensitive indicator of the development of future retinopathy than b-wave amplitude of the scotopic electroretinogram (ERG). Because OPs measured to a bright white flash reflect both rod and cone system activity, it is important to compare OP amplitudes to photopic ERG measures as well as scotopic measures in early diabetic retinopathy. In this study, OPs and ERG responses were measured under photopic and scotopic conditions in a group of diabetic patients. Although OPs were reduced in amplitude in the diabetic group, several other parameters of the scotopic and photopic b-waves were impaired. The results indicate that b-wave activity may indicate retinal changes in early diabetic retinopathy in the same manner as the OPs.

Dark Adaptation↗
PubMed1991

Clinical evaluation of the effects of storage time and irradiation on transfused platelets.

Platelet concentrates stored for up to 5 days at room temperature or irradiated with 15 Gy immediately prior to transfusion were evaluated for their ability to increase the platelet count in thrombocytopenic patients. Platelets irradiated with a dose of 15 Gy immediately prior to transfusion achieved corrected increments (CI) at 1 and 20 h after transfusion no different from those achieved by non-irradiated platelets. Storage for 5 days reduced the mean 1-hour CI to 5.7 compared with a mean of 12.3 achieved by platelets transfused after only 1-day storage (p = 0.008). Similarly, the frequency of a repeat transfusion being indicated within 24 h increased with increasing storage time (p = 0.005).

Blood Platelets↗
PubMed1991

Knowledge about HIV and behavioral risks of foreign-born Boston public school students.

In 1990, 3049 Boston public middle and high school students were surveyed anonymously in English, Spanish, Vietnamese, Chinese, French, or Haitian Creole. Significantly fewer immigrant students, 35% of those surveyed, knew the principal modes of human immunodeficiency virus transmission. Fewer immigrants reported having sexual intercourse (31% vs 53% of nonimmigrants), but among the sexually active only 38% always used condoms, and more immigrants reported intercourse with intravenous drug users (4% vs 1% of non-immigrants). AIDS education should be taught to immigrant students in their native languages.

Adolescent↗