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Biomedical subjects

J F O'Brien

Publications and source records attributed to J F O'Brien.

At least 37 records · Page 2Linked to original sources
PubMed1987

Macroenzyme as a cause of unexplained elevation of aspartate aminotransferase.

Aspartate aminotransferase (AST) can exist as a macroenzyme by forming a complex with an immunoglobulin. This immunoglobulin-complexed macromolecule can cause an elevation in serum AST activity, which may be detected on routine blood chemistry analysis and erroneously considered to indicate the presence of liver disease. Clinicians should be aware of this phenomenon so patients are not subjected to unnecessary procedures. In patients with unexplained AST elevation, liver and muscle disease can be biochemically excluded by the finding of normal serum levels of alanine aminotransferase and creatine kinase. The presence of macro-AST can be determined by exclusion chromatography, electrophoresis, and activation assays with pyridoxal 5-phosphate. The elevated AST values can persist for many years.

Aged↗
PubMed1987

The rib deformity in adolescent idiopathic scoliosis. A prospective study to evaluate changes after Harrington distraction and posterior fusion.

A prospective study to investigate changes in the rib hump or rib deformity after correction of the lateral curvature in adolescent idiopathic scoliosis is reported. The operative treatment for 47 patients was by a Harrington distraction rod and posterior fusion. Before operation and at follow-up, measurements of the Cobb angle, of vertebral rotation, and of the rib deformity were taken. Despite operative correction of the lateral curve, there was a progression of the rib deformity in 64% of the cases after four years. Correction of the lateral curve may thus have no effect on vertebral rotation and cannot be guaranteed to effect a permanent reduction of the rib hump.

Adolescent↗
PubMed1986

Superoxide generation during cardiopulmonary bypass: is there a role for vitamin E?

The cytotoxic metabolites of oxygen [superoxide (O-2), hydrogen peroxide (H2O2), and hydroxyl (OH.)] have been demonstrated to be involved in the peroxidation of membrane lipids consequently altering membrane composition, morphology, and function. Of all the lines of defense adopted by living organisms against toxic oxygen free radicals, vitamin E is most effective in the prevention of membrane damage. Cardiopulmonary bypass (CPB) has been shown to activate complement and cause sequestration of leukocytes which can recruit, adhere, and stimulate release of cytotoxic oxygen radicals. A prospective study of 30 patients evaluated the effects of CPB with and without an exogenous free radical scavenger (Group I, N = 20, control) and (Group II, N = 10, vitamin E) on H2O2 (a marker of oxygen free radicals) malonaldehyde (a marker of lipid peroxidation), transpulmonary leukosequestration, and plasma levels of vitamins E and C. Group I showed a progressive increase in H2O2 during CPB from 65 +/- 6 to 130 +/- 11 micron/ml (P less than 0.0001); plasma vitamin E decreased from 15 +/- 3 to 6 +/- 1 mg/liter (P less than 0.0001) while vitamin C increased from 1.6 +/- .3 to 2.3 +/- .3 mg/dl (P less than 0.0001). Group II showed no significant increase in H2O2 (from 78 +/- 8 to 93 +/- 5 microns/ml) during CPB and a significant reduction in H2O2 levels compared to Group I (P less than 0.001); plasma vitamins E and C did not change significantly in Group II.(ABSTRACT TRUNCATED AT 250 WORDS)

Ascorbic Acid↗
PubMed1986

Macroamylase.

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Acute Disease↗
PubMed1986

Influence of antioxidants (mannitol and allopurinol) on oxygen free radical generation during and after cardiopulmonary bypass.

Oxygen-derived free radicals (O2-, H2O2, OH.) are produced during oxidative metabolism, ischemia and reperfusion, and cardiopulmonary bypass (CPB). When oxygen free radical production exceeds scavenging capacity, peroxidation of structural lipids in cell membranes can occur with potentially injurious consequences. In this prospective study, 45 patients were evaluated to determine the effect of CPB on oxygen free radical generation. Twenty patients in group I were controls. Exogenous oxygen free radical antioxidants were administered before bypass to patients in group II (n = 15, mannitol) and group III (n = 10, allopurinol). In group I, plasma H2O2 increased during extracorporeal circulation from 65 +/- 6.0 to 125 +/- 12 microM/ml (p less than .001). At similar sampling intervals, plasma H2O2 levels were significantly lower in group II (p less than .03) and group III (p less than .05) when compared with those in group I. Red blood cell H2O2 did not change in group I or group II. White blood cell H2O2 levels decreased in group I (p less than .04) and group II during CPB. (Intracellular concentrations of H2O2 were not obtained in group III patients). We conclude that cytotoxic oxygen radicals are generated during CPB and that pretreatment with free radical antioxidants, mannitol or allopurinol, may minimize the free radicals available for lipid peroxidation of biomembranes.

Allopurinol↗
PubMed1986

Oxygen free radical generation during cardiopulmonary bypass: correlation with complement activation.

To determine the relationships among complement activation, pulmonary leukosequestration, and oxygen free radical generation, we prospectively studied 15 patients undergoing cardiopulmonary bypass for myocardial revascularization. Plasma levels of C3a, C4a, and hydrogen peroxide (a marker of oxygen free radical generation) were measured before, during, and after extracorporeal circulation. The results confirm that cardiopulmonary bypass activates complement via the alternate (C3a) pathway. This first phase of complement activation was accompanied by an increase in plasma H2O2 (from 80 +/- 8 to 155 +/- 13 microM/ml; p less than .001) and by pulmonary sequestration of polymorphonuclear leukocytes. Protamine administration after cardiopulmonary bypass further activated complement via the classical (C4a) pathway but was not accompanied by a change in plasma hydrogen peroxide. We hypothesize that both complement activation and excess oxygen free radical generation contribute to the pathophysiology of extracorporeal circulation.

Blood Cells↗
PubMed1985

Assay for beta-glucuronidase in cerebrospinal fluid: usefulness for the detection of neoplastic meningitis.

The specificity and sensitivity of the assay for beta-glucuronidase in cerebrospinal fluid were evaluated to determine the usefulness of this test for the detection of neoplastic meningitis. The enzyme activity was first measured in cerebrospinal fluid from 131 patients with various disorders and was then prospectively measured in cerebrospinal fluid from 30 patients with cytologic results that were positive for or suggestive of malignant disease. Within the first group, elevated levels of beta-glucuronidase were found only among patients with neoplastic processes in the central nervous system, including neoplastic meningitis. Among 26 patients with neoplastic processes in the central nervous system, including neoplastic meningitis. Among 26 patients with positive cytologic results, 13 had elevated beta-glucuronidase activities. Elevated values were more frequent among patients with adenocarcinoma (75%) and myelogenous leukemia (60%). The patients with these two disorders also had the highest enzyme activities. The correlation of th beta-glucuronidase level with other cerebrospinal fluid values, including total protein, glucose content, and cell count, was not significant. The findings of this study indicate that measurement of beta-glucuronidase in cerebrospinal fluid can be used as an adjunctive diagnostic test for neoplastic meningitis. The results should be interpreted with caution, however, because of the possibility that the elevated enzyme levels may be due to acute or subacute bacterial or fungal meningitis.

Cerebrospinal Fluid↗
PubMed1985

Insulin and glucose levels during CPR in the canine model.

Cardiopulmonary arrest and resuscitation produces tremendous physiological stress with resultant biochemical derangements. We undertook this study to determine insulin and glucose levels during cardiopulmonary arrest in the canine model. Baseline insulin and glucose levels were obtained from an ascending aortic arch catheter in six mongrel dogs. Ventricular fibrillation was induced by an electrical stimulus and ventilation was terminated. After five minutes of fibrillation, cardiopulmonary resuscitation (CPR) was initiated using external, mechanical CPR and a continuous epinephrine infusion at 5 micrograms/kg/min. Serum insulin and glucose levels were repeated 15 minutes after beginning CPR. Mean blood glucose 15 minutes after initiation of resuscitation (379 +/- 114 mg/dL) was significantly increased from prearrest levels (124 +/- 29 mg/dL, P less than .01). Mean serum insulin 15 minutes after initiation of resuscitation (11.3 +/- 3.3 microU/mL) was significantly decreased compared to prearrest levels (16.2 +/- 6.0 microU/mL, P less than .05). During ischemia, the myocardium becomes dependent primarily on glucose as a source of energy. Inappropriately low insulin levels during CPR may adversely affect an already compromised myocardial glucose metabolism. Further investigation is needed to determine the utility of insulin infusion during CPR.

Animals↗
PubMed1985

Safe intubation in cervical spine injury.

Traumatic spinal injury is an ongoing community problem. Anatomical stability of the cervical spine depends on the integrity of the bony and ligamentous structures forming the cervical spine. Such stabilising structures are divided into two groups. These are designated anterior and posterior columns. One or both columns may be damaged during traumatic spinal injury. Not all spinal injuries are unstable. Instability may be predicted by viewing anterior-posterior and lateral X-rays of the cervical spine. C1 and C2 injury necessitates special through-mouth views. Instability of the neck requires a different intubation technique. A safe intubation technique is described, the essence of which is to stabilise the neck with longitudinal traction and avoid extension at the fracture site.

Anesthesia↗
PubMed1985

Isolation and preliminary characterization of a monoclonal antibody that interacts preferentially with the liver isoenzyme of human alkaline phosphatase.

We have prepared murine monoclonal antibodies against isolated human bone alkaline phosphatase (ALP, EC 3.1.3.1). Hybridoma supernates were separately screened for reactivity against both human liver and bone ALP. Although most antibody-positive hybrids showed similar reactivity against both isoenzymes, one hybridoma produced an antibody that interacted preferentially with liver ALP. This antibody was purified and used to establish an immunoassay to differentiate liver ALP from bone ALP. When equal activities of the two isoenzymes (as determined by a conventional enzymic assay) were measured by the immunoassay, a fivefold greater response was obtained with liver than with bone ALP. The immunoassay can be used to measure the proportions of the bone and liver isoenzymes in mixtures of them. Cross reactivity with human placental and intestinal ALP is less than 3% relative to liver ALP. These findings support the feasibility of developing immunological methods to differentiate these isoenzymes in the clinical laboratory.

Alkaline Phosphatase↗
PubMed1984

Duplication of part of chromosome 1q: clinical report and review of literature.

We report a male infant with a 47,XY, + der(22),t(1;22)(q32;q11)pat karyotype. Thus, he has duplication of chromosomes 1(q32----qter) and 22(pter----q11). Six patients with dup 1(q32----qter) and eight with dup 1(q42----qter) have been described. These two groups of patients share several manifestations, including postnatal growth retardation; relative macrocephaly with widely separated sutures or large fontanelles; prominent forehead; highly arched palate; micrognathia; downward slant of the palpebral fissures; broad, flat nasal bridge; and apparently low-set, malformed ears. Although many of these abnormalities are nonspecific, partial duplication of 1q should be considered in infants with relative macrocephaly, large fontanelles, and downward slant of the palpebral fissures. Our patient had duplication of the part of chromosome 22 that may be associated with the clinically variable cat-eye syndrome. Patients with dup 22(pter----q11) may also have downward slant of the palpebral fissures, micrognathia, and apparently low-set, malformed ears. The structural gene locus for beta-glucosidase has been mapped to chromosome 1. beta-Glucosidase activity in fibroblasts from our patient was normal, and his parents' activities were not significantly different from those of control individuals. Therefore, either the locus for this enzyme is not present on 1(q32----qter) or the enzyme does not consistently show a substantial gene-dose effect.

Abnormalities, Multiple↗
PubMed1982

Selenium deficiency and fatal cardiomyopathy in a patient on home parenteral nutrition.

An adult patient with chronic idiopathic intestinal pseudo-obstruction maintained on home parenteral nutrition for 6 consecutive years died from cardiomyopathy and ventricular fibrillation. Postmortem examination of the heart revealed widespread myocytolysis and replacement fibrosis similar to that seen in the selenium deficient cardiomyopathy in China (Keshan disease) and animal models. Selenium deficiency in this patient was documented with extremely low concentrations of selenium and decreased activity of the selenoprotein, glutathione peroxidase, in blood, heart, liver, and skeletal muscle. Reports of selenium deficient diets causing myocardial damage in humans and animals and the findings in our patient strongly suggest that his fatal cardiomyopathy was caused by selenium deficiency.

Adult↗
PubMed1981

Serum levels of creatine phosphokinase and its isoenzymes in normal and stressed neonates.

Twenty-six normal newborns (13 male, 13 female) with normal prenatal histories, no perinatal stress, and normal vaginal deliveries had creatine phosphokinase (CPK) activity and isoenzyme activities assayed in cord blood and in 24-hour postpartum serum. Total CPK activity was high in cord blood when compared with adult control values. Moreover, the total CPK was significantly higher in serum at 24 hours of age compared with cord blood. There was a significant increase in both the skeletal muscle isoenzyme and the cardiac muscle isoenzyme from birth to 24 hours of age. There was a decrease in the brain isoenzyme at 24 hours of age which was not statistically significant. These results were compared with values obtained in a group of 10 neonates with severe cardiac problems. Three of the ill neonates had significant elevation of total serum CPK and the skeletal muscle isoenzyme when compared with the normal newborns. There were no significant differences between the normal infants and the ill neonates for the cardiac isoenzyme and the brain isoenzyme. These data suggest that caution should be used in the diagnosis of certain neonatal cardiac syndromes based on serum CPK levels and isoenzyme alone.

Adult↗