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Biomedical subjects

G Crawford

Publications and source records attributed to G Crawford.

At least 91 records · Page 5Linked to original sources
PubMed1989

Increased hydrogen peroxide in the expired breath of patients with acute hypoxemic respiratory failure.

Acute hypoxemic respiratory failure (AHRF) can result from diverse lung insults. Toxic oxygen metabolites have been implicated in this clinical condition and in animal models of pulmonary edema. Hydrogen peroxide (H2O2), an oxygen metabolite, mediates tissue injury. We measured H2O2 levels by a spectrophotometric technique in the breath condensate of 68 mechanically ventilated patients; 13 patients with normal lungs undergoing elective surgery had no such detectable levels of H2O2. Fifty-five patients in the ICU meeting criteria for the adult respiratory distress syndrome (ARDS) had a higher concentration of H2O2 in the expired breath condensate than ICU patients without pulmonary infiltrates (2.34 +/- 1.15 vs 0.99 +/- 0.72 mumol/L, p less than 0.005). This marker had a sensitivity of 87.5 percent and a specificity of 81.3 percent in separating the two patient populations. Patients with AHRF and focal pulmonary infiltrates who did not meet criteria for ARDS also had higher concentrations of H2O2 (2.45 +/- 1.55 mumol/L) than patients without pulmonary infiltrates (p less than 0.001). No difference was observed between the expired H2O2 concentrations of patients with ARDS or patients with focal pulmonary infiltrates. Patients with brain injury or sepsis tended to have higher levels of H2O2 regardless of lung pathology. Increased levels of H2O2 are detected in the expired breath of ICU patients with focal lung infiltrates and in ARDS patients, which is consistent with the hypothesis that oxygen metabolites participate in the pathogenesis of ARDS and other forms of AHRF.

Breath Tests↗
PubMed1988

Restrictive pulmonary dysfunction caused by the grafted chest and abdominal burn.

We report on the effect of the excised and grafted chest and abdominal burn on lung function. Six consecutive patients with 3 degree burns to the entire chest and abdomen (72 +/- 10% total body surface area 3 degree burns) were studied. A severe restrictive lung dysfunction due to the noncompliant nature of the excised and grafted chest and abdominal wound was identified; this was most evident when inspiratory pressure (IP) was even modestly impaired with general anesthetics. Measured vital capacity (VC) was 12 to 14 ml/kg at 6 to 8 wk postburn, in the absence of any significant parenchymal injury. The measured VC was identical to the tidal volume (VT) used during the extended period of mechanical ventilatory support. Dynamic compliance (or characteristic) (Cdyn) decreased dramatically from 35 +/- 8 to 15 +/- 9 ml/cm H2O when the positive pressure VT was increased by as little as 100 ml above prior VT settings, indicating the noncompliant nature of the combined chest and abdominal excised and grafted burn. Major cardiopulmonary complications developed in the first two patients after onset of the restrictive process when general anesthesia was used for grafting procedures (n = 8) and the limits of chest wall excursion were unrecognized. Patients received only continuous positive airway pressure preoperatively. A modest but significant decrease in IP from -45 +/- 8 to -33 +/- 5 cm H2O and 30% decrease in spontaneous VT were noted in the early postoperative period. These changes, however, resulted in a dramatic decrease in pulmonary function leading to hypercarbia, PCO2 greater than 50 torr.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Injuries↗
PubMed1986

Effects of environmental warming on blood components dispensed in syringes for neonatal transfusions.

We examined the quality of blood components dispensed in syringes for transfusion into neonates, including the effects on quality of environmental conditions to which blood is exposed when it is transfused into neonates nursed in warm-air incubators or under radiant warmers. Syringes of blood placed in incubators rapidly warmed to 36 degrees C. Blood placed under radiant warmers operated at full power was heated rapidly to temperatures approaching 45 degrees C, and all blood components exhibited evidence of falling pH and cellular damage after 6 hours exposure to radiant energy. Erythrocyte damage was suggested by an increase in plasma hemoglobin, potassium, and lactic dehydrogenase. Platelets lost the ability to recover from hypotonic shock. Granulocytes exhibited a marked defect in the ability to produce superoxide anion after stimulation. The excessive warming and functional abnormalities exhibited by all blood components exposed to infrared energy were abrogated when syringes were shielded by covering them with aluminum foil. The clinical importance of these experimental findings remains to be established. Meanwhile, it would seem prudent either to shield syringes of blood placed under radiant warmers by covering them with aluminum foil or to limit the volume of a single transfusion to a quantity that can be infused within a relatively brief period.

Blood Transfusion↗
PubMed1984

Psychological and educational correlates of strabismus in school children.

The results of a study investigating the relationship of psychiatric and cognitive disorder with strabismus and its treatment in primary school aged children are reported. Results suggest that children with strabismus have a higher prevalence of psychiatric disorder, particularly an emotional disorder or psychosis. Subjects also had an increased risk of having educational problems and of exhibiting difficulties with tasks involving visual perception. Variables related to the nature and treatment of the strabismus did not appear influential in the development of the psychiatric disorder. Family disruption was significantly associated with both the presence of strabismus and emotional and behavioural problems in the children reported by parents and teachers.

Achievement↗
PubMed1983

Macrophage-mediated cytostatic activity blocks lymphoblast cell cycle progression independently in both G1 phase and S phase.

Recent work has shown that macrophage-mediated cytostatic activity inhibits cell cycle traverse in G1 and/or S phase of the cell cycle without affecting late S, G2, or M phases. The present report is directed at distinguishing between such cytostatic effects on G1 phase or S phase using the accumulation of DNA polymerase alpha as a marker of G1 to S phase transition. Quiescent lymphocytes stimulated with concanavalin A undergo a semisynchronous progression from G0 to G1 to S phase with a dramatic increase in DNA polymerase alpha activity between 20 and 30 hr after stimulation. This increase in enzyme activity was inhibited, as was the accumulation of DNA, when such cells were cocultured with activated murine peritoneal macrophages during this time interval. However, if mitogen-stimulated lymphocytes were enriched for S-phase cells by centrifugal elutriation and cocultured with activated macrophages for 4-6 hr, DNA synthesis was inhibited but the already elevated DNA-polymerase activity was unaffected. Similar results were obtained when a virally transformed lymphoma cell line was substituted as the target cell in this assay. These results show that both G1 and S phase of the cycle are inhibited and suggest that inhibition of progression through the different phases may be accomplished by at least two distinct mechanisms.

Animals↗
PubMed1983

Ventricular tachycardia in a neonate secondary to hyperkalaemia.

We report a preterm infant with ventricular arrhythmias secondary to hyperkalaemia in the first 48 hours of life. The arrhythmias were life threatening and required pharmacological and electrical cardioversion. Aspects of neonatal hyperkalaemia and related arrhythmias are discussed.

Diseases in Twins↗
PubMed1982

Monoclonal antibodies selective for Drosophila melanogaster choline acetyltransferase.

The newly developed monoclonal antibody technology was applied to the production of antibodies selective for Drosophila melanogaster choline acetyltransferase (EC 2.3.1.6). Two stable cell lines, 1C8 and 1G4, were isolated from NS-1/spleen cell hybrids by employing a choline acetyltransferase enzyme activity-screening method. Both cell lines were cloned twice and were maintained in continuous culture and as ascites tumors. Purified antibody was isolated from ascites fluids by pH elution after adsorption to Protein A-Sepharose. Both antibodies eluted from the Protein A-Sepharose as a single subclass, IgG1, and directly inhibited choline acetyltransferase activity. Scatchard analysis of titration data for choline acetyltransferase antibody-enzyme interaction generated linear curves for both antibodies: KA for 1C8 was 2.77 X 10(7) M-1 and KA for 1G4 was 0.78 X 10(7) M-1. Inclusion of the choline acetyltransferase substrate acetyl-CoA at 10 times the KM in the antibody-enzyme reaction mixture substantially reduced the level of inhibition observed with both antibodies; choline, however, exhibited no protective effect. Neither antibody reacted with choline acetyltransferase-containing extracts of vertebrates or other insect neural tissues. We conclude that the two antibodies are nonidentical, monoclonal, and highly selective for D. melanogaster choline acetyltransferase, both reacting at or near the acetyl-CoA binding region of the enzyme-active site.

Animals↗
PubMed1982

Putative 51,000-Mr protein marker for postsynaptic densities is virtually absent in cerebellum.

Cerebrum and cerebellum contain numerous asymmetric synapses characterized by the presence of a postsynaptic thickening prominently stained by phosphotungstic acid and other electron-dense stains suitable for electron microscopy. A 51,000-Mr protein, copurified in postsynaptic density-enriched fractions from cerebrum, is considered to be a well established marker for the postsynaptic density. On the basis of two criteria, our studies demonstrate that the 51,000-Mr protein marker for postsynaptic densities is virtually absent in cerebellum, First, it is present in negligible amounts in deoxycholate-insoluble fractions from cerebellum but abundant in parallel fractions from cerebrum. Secondly, the 51,000-Mr protein, which binds 125I-calmodulin after SDS PAGE is readily visualized in membrane samples from cerebrum but is virtually undetectable in cerebellar samples. It is apparent that these results require reexamination of the role of the 51,000-Mr protein in postsynaptic density structures.

Calmodulin↗
PubMed1981

Practical application of synthetic A and B blood group immunoadsorbents.

The effectiveness of synthetic blood group A and B immunoadsorbents in removing anti-A and anti-B from human sera was evaluated. The sera contained specific alloantibodies and were destined for use as diagnostic reagents. Both Synsorb-A(TM) and Synsorb-B(TM) removed all saline anti-A or anti-B activity from 20 sera tested. All trace of anti-A activity detectable by the indirect antiglobulin test was removed from only 20% of sera; anti-B with similar reactivity was removed from 66% of sera. Specific (wanted) alloantibody titres were reduced by synsorb-A in 60% of sera, but were unaffected by Synsorb-B. Despite these shortcomings, such immunoadsorbents are of value particularly when cells of appropriate phenotype are unavailable for absorptions.

ABO Blood-Group System↗
PubMed1979

Streptococcal pharyngitis: diagnosis by gram stain.

Group A beta-hemolytic streptococci were isolated from 49 (10.4%) of 472 patients with pharyngitis. Throat culture results, interpreted by five observers of varying experience, showed the mean sensitivity, specificity, and predictive value of a positive Gram-stained smear of pharyngeal secretions as 73%, 96%, and 71%. Assignment to a high-risk group by clinical algorithm gave sensitivity, specificity, and predictive value of only 45%, 83%, and 23%. The Gram-stained smear is the most accurate method of early diagnosis of streptococcal pharyngitis.

Adolescent↗