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Biomedical subjects

T O'Connor

Publications and source records attributed to T O'Connor.

At least 19 recordsLinked to original sources
PubMed1992

Adenotonsillectomy for upper airway obstruction carries increased risk in children with a history of prematurity.

To define better the clinical presentation and perioperative outcome in children undergoing adenotonsillectomy (T&A) for relief of upper airway obstruction (UAO), we reviewed the hospital records of 60 consecutive, otherwise normal children aged 12 years or younger. Seven patients with trisomy 21, neurologic impairments, or preoperative cor-pulmonale were excluded. Intraoperative and postoperative complications were experienced by 15 (34%) and 13 (25%), respectively, of the 53 children with preoperative UAO. The most severe complications comprised pulmonary edema and prolonged postoperative oxyhemoglobin desaturation. Multivariate logistic regression analysis found a history of prematurity and/or low birth weight to be the most significant risk factors related to the occurrence of complications. Twenty-eight % of the study population had a history of prematurity and they had approximately 85% of the perioperative complications seen in children with UAO undergoing T&A. Other significant risk factors included adenoidal facies and evidence of respiratory distress at the time of surgery. It appears that T&A poses significant risk for children with UAO who were born prematurely and have evidence of abnormal facial development or respiratory distress preoperatively.

Adenoidectomy↗
PubMed1992

Acute and multiple injection effects of magnesium on responding maintained by cocaine, extinction from cocaine, glucose + saccharin, and food.

In a variety of behavioral experiments, magnesium has effects that are similar to cocaine and other psychomotor stimulants. Of particular relevance to the present experiments is the recent finding that magnesium maintains responding in cocaine-trained rats. It would be expected, therefore, that injections of magnesium would alter the rate of responding maintained by self-administered cocaine in rats. Five experiments examined the specificity and selectivity of this interaction. Acute and multiple injections of MgCl2 (15-250 mg/kg) produced dose-dependent reductions in responding maintained by cocaine (0.1-2 mg/kg/infusion). Testing for acute injection effects occurred following injections, while testing for multiple injection effects occurred prior to daily injections. Doses of 30 and 125 mg/kg MgCl2 reduced responding maintained by doses of cocaine that were below the training dose of 0.75 mg/kg/infusion. MgCl2 in a dose of 250 mg/kg markedly suppressed responding maintained by each dose of cocaine. A magnesium-deficient diet produced a dose-dependent increase in responding maintained by 0.1 mg/kg/infusion cocaine. In order to determine the specificity and selectively of these effects, acute and multiple injections of MgCl2 were examined on glucose + saccharin- and food-maintained responding. The acute effects of MgCl2 injections were specific because food-maintained responding was not affected, except by the highest dose of 250 mg/kg. This demonstrates that lever pressing was not nonspecifically reduced by 30 and 125 mg/kg MgCl2 during cocaine availability. However, the effects on cocaine-maintained responding were not selective for cocaine because glucose + saccharin-maintained responding and responding during extinction from cocaine were affected by MgCl2 in a manner similar to cocaine-maintained responding.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Fetuses with Down syndrome have disproportionately shortened frontal lobe dimensions on ultrasonographic examination.

OBJECTIVE: The purpose of our study was to determine whether the frontal lobe is significantly smaller than normal in the Down syndrome fetus in midtrimester. STUDY DESIGN: Frontothalamic distance, measured from the inner table of the frontal bone to the posterior thalamus, and frontothalamic distance/biparietal diameter ratio were compared in 125 normal and 19 Down syndrome fetuses between 16 and 21 weeks' gestation. RESULTS: In the Down syndrome group 52% had frontothalamic distance < 10th percentile. When the frontothalamic distance and the frontothalamic distance/biparietal diameter ratio were expressed as multiples of the normal median to eliminate variation caused by gestational age, the mean value of multiples of the median in Down syndrome fetuses was compared with the mean value of multiples of the median in normal fetuses and was found to be significantly smaller (p < 0.0019 and p < 0.0177, respectively). When an observed-to-expected frontothalamic distance ratio of < or = 0.84 is used as a cutoff to screen for Down syndrome, sensitivity, specificity, and positive predictive values of 21.2%, 95.2%, and 1.2%, respectively, are achieved in a population with a 1:270 risk. CONCLUSION: Frontal lobe dimension is significantly shortened in Down syndrome fetuses.

Down Syndrome↗
PubMed1992

Predictive value of the human immunodeficiency virus 1 antigen test in children born to infected mothers.

Our objective was to examine the utility of the human immunodeficiency virus (HIV-1) antigen test as an early predictor of HIV-1 infection among children born to infected mothers and to collect information about its performance as a diagnostic test. The Abbott HIVAG-1 Enzyme Immunoassay was used to analyze serial serum samples from patients enrolled in a longitudinal cohort study of children born to mothers infected with HIV-1. There were 85 subjects who were followed from birth whose HIV-1 infection status could be definitely determined as of March, 1990. Of these 22 (26%) were infected with HIV-1 and 63 (74%) were uninfected. Overall the sensitivity of the test was 77% (95% confidence interval (CI), 55 to 92%) and the specificity was 97% (95% CI, 89 to 99%). The positive predictive value of a single positive test was 89% (95% CI, 67 to 99%) and of two or more positive tests was 100% (95% CI, 50 to 100%). The sensitivity of the test varied greatly with age. For 36 children from whom sera were collected during the first month of life the specificity of the antigen test was 100% but the sensitivity was only 20%. Overall in the first 6 months of life the sensitivity was less than 50%. The Abbott HIV-1 antigen test is useful as an early predictor of HIV-1 infection in children whose mothers are infected.

Child, Preschool↗
PubMed1992

Complications occurring in the postanesthesia care unit: a survey.

To identify and quantitate complications occurring in the postanesthesia care unit (PACU), a prospective study evaluated 18,473 consecutive patients entering a PACU at a university teaching hospital. Using a standardized collection form, the incidence of intraoperative and PACU complications was determined. The combined PACU and intraoperative complication rate was 26.7%. Data showed a PACU complication rate of 23.7%, with an overall intraoperative complication rate of 5.1%. Nausea and vomiting (9.8%), the need for upper airway support (6.9%), and hypotension requiring treatment (2.7%) were the most frequently encountered PACU complications. Patients in whom PACU complications developed were analyzed by ASA physical status. Of all patients experiencing nausea and vomiting (n = 1571), the highest percentage were ASA physical status II patients (n = 831). Likewise, in the group of 1450 patients who demonstrated a need for upper airway support, 792 were ASA physical status II. In patients experiencing a major cardiovascular complication, for example, variables associated with a greater risk of developing any PACU complications were ASA physical status (status II), duration of anesthesia (2-4 h), anesthetic technique, emergency procedures, and certain types of surgical procedures (orthopedic or abdominal). For patients admitted with a temperature of less than 35 degrees C the duration of the PACU stay was 152 +/- 46 min compared with 116 +/- 65 min for patients with a temperature greater than or equal to 36 degrees C (P less than 0.01). In conclusion, events occurring during the PACU period continue to be a source of patient morbidity.

Adolescent↗
PubMed1992

Community assessment.

Explore the source record for details and available documents.

Community Health Nursing↗
PubMed1992

Prophylactic intravenous ondansetron in female outpatients undergoing gynaecological surgery: a multicentre dose-comparison study.

The efficacy and safety of prophylactic intravenous ondansetron in preventing postoperative nausea and vomiting was investigated in a randomized, stratified, double-blind, placebo-controlled, dose-comparison study of 580 ASA physical class I and II female outpatients undergoing gynaecological surgery and receiving general anaesthesia. Patients received either ondansetron 1, 4 or 8 mg, or placebo i.v. immediately prior to a standardized technique for induction and maintenance of anaesthesia. All patients were intubated and received nitrous oxide and a narcotic. All doses of ondansetron were significantly more effective than placebo in preventing emesis over the 24 h postoperative period. Ondansetron significantly decreased nausea and emesis scores over 24 h postoperatively without causing sedation. No changes in laboratory parameters (haematology, blood chemistry, and liver enzymes) or vital signs (heart rate, blood pressure, and respiratory rate) were observed. Headache and dizziness were the most common side-effects; however, their incidence was the same as with placebo. Ondansetron was generally well tolerated, as evidenced by an adverse event, laboratory safety, and vital sign profile similar to placebo. Ondansetron 4 mg was found to be the optimal prophylactic i.v. dose for female outpatients over the entire 24 h postoperative period. Higher doses may offer an added benefit in some patients, such as those with a history of nausea and vomiting following general anaesthesia.

Adult↗
PubMed1991

myc family DNA amplification in 107 tumors and tumor cell lines from patients with small cell lung cancer treated with different combination chemotherapy regimens.

We studied 107 specimens (38 tumors and 69 tumor cell lines) from 90 patients with small cell lung cancer to determine the characteristics and clinical situations of patients from whom tumor cell lines could be established and the myc family DNA copy number. The proportion of extensive stage small cell lung cancer patients from whom a tumor cell line could be established prior to the initiation of therapy increased during the 10 years of the study (P less than 0.001). Amplification of one of the myc family genes occurred in 3 of 40 (8%) of the untreated patient specimens compared to 19 of 67 (28%) of the treated patient specimens (P = 0.01). The myc family DNA amplification occurred in 17 of 54 (31%) of the specimens from patients treated with cyclophosphamide-based combinations and 2 of 13 (15%) of the specimens from patients treated with etoposide/cisplatin (P = 0.25). Both tumors and tumor cell lines were obtained from 17 patients with small cell lung cancer and the myc family DNA copy number was similar in 16 of the 17 patients. We conclude that: (a) myc family DNA amplification occurs more commonly in specimens from treated than untreated patients (b) there are no prominent differences in the frequency of amplification following treatment with different chemotherapy regimens; and (c) myc family DNA amplification is similar in tumors and tumor cell lines from the same patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Intermolecular cross-links mediate aggregation of phospholipid vesicles by pulmonary surfactant protein SP-A.

As the most abundant glycoprotein component of pulmonary surfactant, SP-A (Mr = 30,000-36,000) plays a central role in the organization of phospholipid bilayers in the alveolar air space. SP-A, isolated from lung lavage, exists in oligomeric forms (N = 6, 12, 18, ...), mediated by collagen-like triple helices and intermolecular disulfide bonds. These protein-protein interactions, involving the amino-terminal domain of SP-A, are hypothesized to facilitate the alignment of surfactant lipid bilayers into unique tubular myelin structures. SP-A reorganization of surfactant lipid was assessed in vitro by quantitating the calcium-dependent light scattering properties of lipid vesicle suspensions induced by SP-A. Accelerated aggregation of unilamellar vesicles required SP-A and at least 3 mM free calcium. The initial rate of aggregation was proportional to the concentration of canine SP-A over lipid:protein molar ratios ranging from 200:1 to 5000:1. Digestion with bacterial collagenase or incubation with dithiothreitol (DTT) completely blocked lipid aggregation activity. Both treatments decreased the binding of SP-A to phospholipids. The conditions used in the DTT experiments (10 mM DTT, nondenaturing Tris buffer, 37 degrees C) resulted in the selective reduction and 14C-alkylation of the intermolecular disulfide bond involving residue 9Cys, whereas the four cysteines found in the noncollagenous domain of SP-A were inefficiently alkylated with [14C]-iodoacetate. HPLC analysis of tryptic SP-A peptides revealed that these four cysteine residues participate in intramolecular disulfide bond formation (138Cys-229Cys and 207Cys-221Cys). Our data demonstrate the importance of the quaternary structure (triple helix and intermolecular disulfide bond) of SP-A for the aggregation of unilamellar phospholipid vesicles.

Amino Acids↗
PubMed1991

Hyporegenerative anemia associated with intrauterine transfusion in rhesus hemolytic disease.

Serial erythropoietin and ferritin levels were monitored in a fetus and newborn requiring three intravascular transfusions (in utero) for severe Rh disease. The newborn had a hematocrit of 37% at birth; however a hyporegenerative transfusion-dependent anemia developed and lasted approximately 3 months. The prolonged hyporegenerative anemia may be caused in part by erythropoietin suppression as a result of the fetal intravascular transfusions. In addition, anti-D antibody may also contribute to this anemia by a direct toxic effect on erythroid precursors and by peripheral hemolysis of reticulocytes.

Adult↗
PubMed1991

Does intensive glycemic control in diabetic pregnancies result in normalization of other metabolic fuels?

Intensive treatment of insulin-dependent diabetes mellitus during pregnancy often normalizes plasma glucose levels. However, it is unclear whether this adversely affects other metabolic fuels that are essential to normal fetal growth and development. Metabolic studies were conducted after the subjects ingested a standardized mixed meal during each trimester in 7 normal and 15 insulin-dependent diabetic pregnant women. The latter were treated with continuous subcutaneous insulin infusion or multiple injections, which were adjusted to achieve strict glucose control throughout pregnancy. Insulin, alanine, branched-chain amino acids, triglycerides, free fatty acids, and ketones were measured every 15 to 30 minutes before a standardized breakfast and for 150 minutes after the breakfast. Patients with insulin-dependent diabetes mellitus were studied while they received their unusual insulin dosages. Fasting glucose levels (87 +/- 7 mg/dl) and glucose levels 150 minutes after the meal (112 +/- 11 mg/dl) were near normal. However, normoglycemia was achieved at the expense of increased plasma insulin levels (area under insulin response curves, p less than 0.01, vs nondiabetic curves). Nevertheless, fasting and post-prandial plasma branched-chain amino acids, alanine, and free fatty acids were similar in both groups. Fasting cholesterol, triglyceride, and ketone levels were also normalized. We conclude that normalization of circulating amino acids and lipids in conjunction with correction of hyperglycemia may contribute to favorable outcomes in infants of intensively treated diabetic mothers.

Adult↗
PubMed1991

Is the pressure rate quotient a predictor or indicator of myocardial ischemia as measured by ST-segment changes in patients undergoing coronary artery bypass surgery?

Perioperative myocardial ischemia is associated with an increased risk of perioperative myocardial infarction (PMI). Several attempts have been made to define intraoperative hemodynamic predictors of myocardial ischemia. In a canine preparation with coronary stenosis, a pressure rate quotient (PRQ = mean arterial pressure/heart rate) less than one (PRQ less than 1) indicated subendocardial myocardial ischemia. The authors tested this hypothesis in patients undergoing elective coronary artery bypass graft operation (CABG), using electrocardiogram (ECG) ST-segment changes (leads II/V5) to diagnose myocardial ischemia. Sixty (n = 60) patients having CABG surgery were prospectively studied before initiation of cardiopulmonary bypass. Calibrated ECG leads II and V5 (diagnostic mode) were monitored continuously and recorded with the use of a Hewlett-Packard computer ST-segment analyzer. In addition, arterial and pulmonary artery pressures were monitored. Ischemia was defined as new-onset ST deviation (greater than or equal to 1 mm from the baseline ECG). ECG and hemodynamic data were stored at 2-min intervals for subsequent computer analysis. Serial creatinine phosphokinase (CPK) X MB (%) determinations and 12-lead ECGs were collected for the initial 3 postoperative days. Of the 3,463 intervals (2 min) available for study, 3,322 (96%) were satisfactorily recorded for 60 patients. Ischemia occurred during 65 intervals in 9 patients (9 of 60), of which only 34% (22 of 65) were associated with a PRQ less than 1 (P less than 0.01). In contrast, there were 466 intervals during which PRQ was less than 1, but without ECG evidence of ischemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Continuous infusion of interleukin-2 and cyclophosphamide as treatment of advanced cancers: a National Biotherapy Study Group Trial.

We have evaluated the effect of Interleukin-2 [IL-2] after Cyclophosphamide (C) chemotherapy in 41 patients with metastatic cancer. IL-2 was given as a continuous infusion priming cycle 36 hours after C at 1 gm/m2 intravenously. In 39 evaluable patients, there were no complete remissions [CR], 2 partial remissions [PR], and 1 had a minor response [MR]. Stable disease for 30 days was seen in 16 patients whereas 20 progressed. The durations of partial and minor responses were brief, ranging from 1-6 months. Grade 3-4 neutropenia was seen in 41%. This was more severe than seen with IL-2 alone or IL-2 combined with lower doses of C. The marrow suppression was due to the chemotherapy. This combination of IL-2 and C appears to be reasonably well tolerated by patients, but toxicity is greater and the response rate is no better than results achieved by IL-2 alone. Responses of 26 patients with renal cancer appear to be inferior to our historical data using IL-2/LAK cells without C. Immune monitoring demonstrated changes expected with C chemotherapy (i.e., a non-selective decline in immune function). C induced no further differences in IL-2 induced changes in immune function.

Adult↗
PubMed1990

Tumor cell lines established in vitro: an independent prognostic factor for survival in non-small-cell lung cancer.

OBJECTIVE: To determine the relation between in-vitro establishment of tumor cell lines and survival in patients with non-small-cell lung cancer. DESIGN: Cohort study. SETTING: Single-institution tertiary care center. PATIENTS: One hundred twenty-three consecutive patients with non-small-cell lung cancer from whom a viable tumor specimen could be obtained. INTERVENTION: Tumor tissue was removed at the time of entry into a therapeutic protocol. The tumor tissue was processed in the laboratory for attempted cell-line establishment. Patients classified as potentially curable (stages I, II, and IIIA) were treated with surgical resection, radiation therapy, or a combination. Patients suitable for palliative therapy only (stages IIIB and IV) were treated with radiation therapy with or without chemotherapy. Chemotherapy was based on in-vitro drug sensitivity when available. Cell-line establishment was correlated to clinical outcome. MEASUREMENTS AND MAIN RESULTS: Univariate analysis of survival was done using the log-rank test; multivariate analysis was done by Cox modeling step-up and step-down techniques. Cell lines were established from the tumor specimens of 25 patients (20%). Those patients experienced a median survival of 7 months compared with 18 months in patients from whom cell lines could not be established (P less than 0.001). In the 61 patients with potentially curable disease, 8 patients (13%) with cell lines established had a median survival of 8 months compared with 32 months for those without cell lines established (P = 0.001). In the 62 palliative group patients, the median survival of the 17 patients (27%) from whom tumor cell lines were established was 5 months compared with 7 months for those without cell lines (P = 0.15). Multivariate analysis in both groups showed cell-line establishment to be a significant indicator of prognosis (P less than 0.0001 for curable group; P less than 0.01 for palliative group). CONCLUSION: In-vitro tumor growth is related to decreased patient survival, which in turn reflects the biologic aggressiveness of cancers giving rise to these tumor cell lines.

Analysis of Variance↗