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Biomedical subjects

R Carr

Publications and source records attributed to R Carr.

At least 91 records · Page 5Linked to original sources
PubMed1990

Abnormal FcRIII expression by neutrophils from very preterm neonates.

To further investigate the neutrophil dysfunction of newborn infants, we have measured expression of the neutrophil Fc gamma receptors FcRIII and FcRII in extremely immature preterm neonates born at 24 to 32 weeks of gestation. Fc receptor expression was measured by FACS analysis of cells stained with monoclonal antibody Leu11b for FcRIII and IV-3 for FcRII. "Well" preterm neonates displayed reduced FcRIII, 51.05 +/- 2.0 (mean fluorescence channel +/- SE) when compared with term neonates, 69.24 +/- 5.5 and adult controls, 71.83 +/- 3.0. "Stressed" preterm neonates with severe respiratory distress syndrome or septicemia had a further downregulation of FcRIII, 32.67 +/- 3.0 and 35.75 +/- 1.8, respectively, associated with grossly abnormal cellular fluorescence distribution. In well preterm neonates, expression of FcRIII improved to adult levels during the first two postnatal weeks, suggesting a postnatal maturation of function. Stressed neonates had signs of partial neutrophil activation (increased Mac-1 expression and chemotactic ability), leading us to propose that the further downregulation of FcRIII may be due to receptor shedding in vivo by partially activated cells. FcRII expression was found to be equivalent to adult levels in both well preterm and stressed neonates. Reduced neutrophil FcRIII expression may provide some explanation for the reported abnormalities of phagocytosis and bacterial killing in preterm neonates.

Antigens, Differentiation↗
PubMed1990

Transfusion of ABO-mismatched platelets leads to early platelet refractoriness.

Forty-three consecutive patients previously unexposed to platelets and undergoing treatment for acute leukaemia or autografting for relapsed Hodgkin's lymphoma were randomized to receive transfused platelets of either their own ABO group (OG) or of a major mismatched group (MMG). The 26 evaluable patients were equally distributed between the two study groups. Nine of 13 (69%) MMG patients became refractory with a median onset at transfusion 7 (15 d), compared with only one of 13 (8%) OG patients (P = 0.001). Refractoriness was associated with the formation of high titre isoagglutinins, anti-HLA and platelet specific antibodies. In one patient refractoriness appeared to be due to high titre isoagglutinins alone. Six other patients developed an increase in isoagglutinin titre sufficient to adversely affect platelet increments. Patients receiving ABO-mismatched platelets had a higher incidence of anti-HLA antibodies (5 v. 1) and platelet specific antibodies (4 v. 1). ABO-mismatched platelets transfused prior to the onset of refractoriness resulted in increments similar to those achieved by ABO-matched platelets. The study demonstrates that ABO-mismatched platelets are as effective as matched platelets in patients with low titre isoagglutinins requiring only few transfusions. However, the greater incidence of early refractoriness induced in MMG patients indicates that ABO-mismatched platelets should not be given to patients with marrow failure requiring long-term support.

ABO Blood-Group System↗
PubMed1990

Hue discrimination and S cone pathway sensitivity in early diabetic retinopathy.

Measures of hue discrimination and M (green) and S (blue) cone pathway sensitivities were compared in a group of 24 diabetics with either early background retinopathy or no retinopathy. The Farnsworth-Munsell 100-hue test was used to measure hue discrimination, and a two-color increment threshold technique was used to measure S and M cone pathway sensitivities. The results were compared to the level of diabetic retinopathy, to the degree of macular edema, and to the duration of the disease. No significant correlation was found between the Farnsworth-Munsell 100-hue error scores and the level of retinopathy; S cone pathway sensitivity loss, however, correlated significantly with both the level of retinopathy and the degree of macular edema. Our results indicate that measurements of S cone pathway sensitivity using an increment threshold technique provide a more sensitive method than hue discrimination for detecting color vision deficits in early diabetic retinopathy.

Adult↗
PubMed1989

Losses of temporal modulation sensitivity in retinal degenerations.

Sensitivity losses in patients with retinitis pigmentosa (RP) have been attributed to a decrease in photopigment density, to a reduction in the number of photoreceptors, and also to a change in temporal response properties of the receptors. The sensitivity losses in patients with macular degeneration have also been attributed to a loss of photoreceptors. To test these explanations for sensitivity loss we obtained electrophysiological and psychophysical temporal modulation transfer functions (MTFs) on normal subjects in response to varying stimulus luminances and retinal loci. These stimulus manipulations did not duplicate the changes observed in the temporal MTFs of patients. The temporal response properties of the receptors were tested electrophysiologically by manipulating stimulus presentation interval. The results provided evidence for sensitivity losses in RP patients being due to alterations in the temporal response properties of the receptors.

Aged↗
PubMed1988

Changes in the focal electroretinogram with retinal eccentricity.

Flicker sensitivity increases in the peripheral retina when relatively large targets are used. This enhancement of cone system-mediated temporal sensitivity persists even when corrections are made for cortical magnification factors. It has been suggested that the differences in temporal frequency response characteristics across the retina are based on differences in receptor morphology between the peripheral and central cones. We have examined a possible retinal origin of this phenomenon by obtaining psychophysical and electroretinographic data at a variety of locations on the temporal retina. Psychophysical results show an increased sensitivity for high temporal frequency stimuli (above 30 Hz) with retinal eccentricity whether or not the stimulus size was scaled. Focal electroretinograms recorded with a constant size stimulus did not show an increase in amplitude with eccentricity. However, when an equal number of receptors were stimulated by scaling the target size, focal amplitudes were larger in the periphery. The electrophysiological findings are consistent with a possible retinal origin for this flicker enhancement phenomenon.

Contrast Sensitivity↗
PubMed1988

The immunologic composition of neonatal milk: cellular components.

The cellular content of neonatal mammary gland secretions from 12 full-term infants less than 2 weeks postdelivery was studied. The predominant cell types observed were lymphocytes and macrophages with greater than 90% viability in each. The concentration of lymphocytes was significantly (P less than 0.001) correlated with the concentration of macrophages. The immunoglobulin content of this fluid was predominantly IgG with minimal concentrations of IgA, and no IgM detected. These data suggest both the presence of regulatory mechanisms for the cellular composition of neonatal breast secretions and that neonatal milk may bear a significant connection with the developing mucosal immune system.

Humans↗
PubMed1987

Histopathology and immunofluorescent immunoglobulins in asthmatics with aspirin idiosyncrasy.

Nearly 700 specimens of polyps and sinus tissues from 12 patients with asthma and aspirin idiosyncrasy were studied with histochemical and immunofluorescent immunoglobulin techniques. Hematoxylin-eosin, Giemsa, and Wright's stains were used for the histochemical analyses. Immunofluorescent antibodies for IgG, IgA, IgM, IgE, IgD, anti-C3, albumin, and fibrin were used. There was a uniform inflammatory reaction in all the tissues. A thick basement membrane and epithelial changes were also present. Immunofluorescent immunoglobulins were consistent in quantity and location in these tissues. IgG, IgA, and IgM were associated with inflammation. IgE was present in all the specimens, but this does not necessarily indicate a reagin-mediated reaction. Anti-C3 excluded the possibility of a hereditary absence of C1 esterase inhibitor.

Adult↗
PubMed1987

Abnormal responses to ingested substances in murine systemic lupus erythematosus: apparent effect of a casein-free diet on the development of systemic lupus erythematosus in NZB/W mice.

To assess the development of oral tolerance to casein in NZB/W female mice, they must be bred and raised on a casein free diet. We examined the specific immune responses of the mice to the long term experimental feeding of casein. Twelve of fifteen casein free mice were still alive at 10 months of age, although by this age only 1/10 mice eating the normal diet was still alive. The casein free mice had markedly less anti-DNA antibody, their IgM to IgG antinative DNA switch was delayed and deposits of immunoreactants in the glomeruli were greatly decreased. The reason for this apparent effect of the removal of casein from the diet is unknown; however, immunostimulatory and endorphin-like regions have recently been reported in casein.

Animals↗
PubMed1986

Electrophysiological assessment of aphakic cystoid macular oedema.

Focal electroretinograms (FERG), pattern electroretinograms (PERG), and visual evoked potentials (VEP) were studied in a group of 30 aphakic patients with cystoid macular oedema (ACME). When compared with a control group of age-matched aphakics, 35% of patients were found to have abnormal FERG responses and 53%--over half of whom had normal FERG responses--showed abnormal PERG amplitudes. Although most of the patients had associated optic disc leakage, VEP latencies were normal in 26 out of 30. These results may explain the more severe visual loss seen in some ACME patients where the ophthalmologically visible retinal changes do not seem sufficient to explain such reduction in vision.

Adult↗
PubMed1986

A comparison of three anti-double stranded DNA antibody assays on sera from SLE and other diseases.

Systemic lupus erythematosus (SLE) is a multisystem disorder accompanied by a diverse spectrum of serum autoantibodies. Antibodies to double stranded DNA (dsDNA) are considered to be the most specific marker for this disease. In this study the results obtained from three different assays for dsDNA are compared: an indirect fluorescence antibody assay (IFA), a radioimmunoassay (RIA) and, an enzyme-linked immunosorbent assay (ELISA), on 57 SLE sera and 28 Sera from other disorders. Correlation of these anti-DNA results are made with C3, C4, and antinuclear antibody (ANA) titers. Our results show the IFA assay is the most sensitive and the least specific of the three tests. The RIA was found to be the most specific and was approximately as sensitive as the ELISA. We also found significant inverse correlations between anti-dsDNA levels and circulating complement levels among SLE sera for all three assays. ANA titers were significantly correlated with all anti-dsDNA assays as well. However, these anti-dsDNA assays show only modest differences explainable by numerous mechanisms. Hence, a clearly superior anti-dsDNA method does not emerge from our study.

Antibodies, Antinuclear↗