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Biomedical subjects

E M McCann

Publications and source records attributed to E M McCann.

10 recordsLinked to original sources
PubMed1997

A comparison of polydipsia prevalence among chronic psychiatric patients using three measurement approaches.

Many previous prevalence studies of polydipsia (PD) have utilized single and often non-biologic measures. In this study we estimated prevalence using specific gravity of urine (SPGU), normalized diurnal weight gain (NDWG), and staff identification (staff ID). Agreement between these two biologic and one behavioral measure was assessed. A total of 572 psychiatric inpatients were assessed for SPGU and NDWG. Unit staff were asked to identify PD patients. Positive and negative PD groups were formed separately based on the SPGU, NDWG, and staff ID data. All three measures were collected on the same day. Prevalence data for the biologic measures varied. The estimate for PD by SPGU (< 1.009 cutoff) was higher (43.4% of sample) than that of NDWG (> 2.5%; 25.4%) or staff ID (21.4%). These prevalence rates did not change substantially after exclusion of medical causes of polyuria. Agreement, assessed by the kappa statistic, was uniformly low among the measures. Weak association between the measures reflects their multidetermined, nonspecific nature, and highlights the lack of a diagnostic standard in the field. The observed prevalence rates must be considered rough approximations. Associations between the measures and certain subject characteristics suggest the measures may identify different types of potential PD patients. These different types of patients are discussed, as are other issues in the measurement of PD. The data suggest estimates of PD are a function of the type of measure used as even biologic measures vary greatly.

Adult↗
PubMed1997

Location of cis-acting signals important for RNA encapsidation in the leader sequence of human immunodeficiency virus type 2.

We used a series of deletion mutations in the untranslated leader region of human immunodeficiency virus type 2 (HIV-2) to seek cis-acting packaging signals. Sequences between the 5' major splice donor and the gag initiation codon, where such signals have been identified in HIV-1, appear to make a measurable but very minor contribution to genomic RNA packaging, and deletions here had little effect on viral replication in vitro. Immediately 5' to the splice donor, two regions were identified which, when deleted, caused a significant replication defect. The most proximal of these to the splice donor demonstrated a phenotype consistent with its being a major cis-acting packaging signal in HIV-2.

Animals↗
PubMed1996

Repetitive behaviors in schizophrenia: a single disturbance or discrete symptoms?

Schizophrenia patients often display multiple repetitive behaviors. We investigated relations among nine repetitive behaviors and evaluated the hypothesis that these behaviors are varied manifestations of a single underlying biobehavioral disturbance. Nine repetitive behaviors from the Elgin Behavioral Rating Scale were assessed in 400 schizophrenia patients residing at a state hospital. A majority of patients were smokers (76.3%) and very few had pica (3%). Several other repetitive behaviors showed substantial frequency. A principal components analysis revealed eight of nine behaviors shared at least 10% of their variance with a single, common component. However, a principal factor analysis suggested a five-factor model best represented the data. The five factors and items identifying them were: (1) 'oral consumption' behaviors-polydipsia and smoking; (2) 'Kluver-Bucy' behaviors-bulimia and hypersexuality; (3) 'movement' behaviors-mannerisms/postures and pacing; (4) 'bizarre use of objects'-bizarre grooming and hoarding; (5) 'Pica'. Associations among repetitive behaviors varied. Symptoms such as smoking and polydipsia appeared reliably related, and others such as pica appeared discrete and independent. Overall, the data did not support the 'single disturbance' hypothesis and suggested a multifactorial model is needed to characterize repetitive behavior disturbances in schizophrenia.

Adult↗
PubMed1991

Inspiratory time and pulmonary function in mechanically ventilated babies with chronic lung disease.

To learn if increasing inspiratory time would improve pulmonary function in mechanically ventilated babies with chronic lung disease, we measured lung mechanics and alveolar ventilation at three inspiratory times: 0.4, 0.6, and 0.8 s. Nine babies were studied. Their mean birth weight was 875 g (range, 570-1,100 g), gestational age 27 (24-34) weeks, and age 7 (4-12) weeks. Their mean oxygen requirement was 40% (29-53), ventilator rate 33/min (20-40), and mean airway pressure 8 (5-10) cmH2O. Ventilator rate was kept constant; therefore expiratory time decreased and mean airway pressure and I:E ratio increased at longer inspiratory times. At 0.6 s and 0.8 s, when compared to 0.4 s, significant increases occurred in tidal volume (10.4, 10.1, and 8.4 mL/kg, respectively), dynamic lung compliance (0.68, 0.68, and 0.53 mL/cmH2O/kg, respectively), and alveolar ventilation (6.0, 6.3, and 4.7 mL/kg/breath, respectively). Airway resistance, anatomical dead space to tidal volume ratio, and functional residual capacity were similar at the three inspiratory times. Our findings suggest that an inspiratory time greater than or equal to 0.6 s (compared to 0.4 s) increases the effectiveness of mechanical ventilation for babies with chronic lung disease.

Chronic Disease↗
PubMed1991

Control of breathing in babies of narcotic- and cocaine-abusing mothers.

To learn if chemoreceptor control of breathing is abnormal in babies whose mothers took narcotics, cocaine, or both drugs during pregnancy, we performed hypoxia and hypercapnia challenges on 28 babies (greater than or equal to 36 weeks gestation). Six babies were exposed to narcotics, six to cocaine, nine to both drugs, and seven babies were controls. Studies were done at 3 and 8 weeks and 3 and 5 months of age. Gestational ages were similar, but birth weight was lower in the cocaine group. Respiratory rate was higher in both groups of cocaine-exposed babies at 3 weeks. End-tidal partial pressure of CO2 (PCO2) was decreased and partial pressure of O2 (PO2) increased at 3 and 8 weeks in babies exposed to narcotics plus cocaine. At 3 weeks, babies exposed to narcotics plus cocaine had a shift to the left in CO2 response with a normal slope; at 8 weeks, both intercept and slope were decreased. Responses to hypoxia were similar among the four groups. Babies exposed to narcotics plus cocaine before birth have abnormalities in control of breathing in the first months after birth.

Birth Weight↗
PubMed1988

Does gastric acid protect the preterm infant from bacteria in unheated human milk?

Although preterm mother's milk has greater nutritional and anti-infective properties than donor milk, it may be highly contaminated with bacteria. We therefore asked three questions: what is the fate of these bacteria in the preterm infant's stomach, is gastric pH important, and what factors affect gastric pH? pH, colony count and bacterial identification were performed on the milk and on serial gastric aspirates in 20 preterm infants on 25 occasions. Seventeen milk samples grew bacteria, five potentially pathogenic and 12 non-pathogenic. Twelve of 25 prefeeding gastric samples were sterile, but following the feeding all the samples grew non-pathogenic bacteria and 70% grew potential pathogens. With time pH decreased and by 2-h samples with pH less than 3.5 had no bacterial growth; Candida albicans still flourished in a low pH (mean 2.8). We concluded that a low gastric pH may be more important than the bacterial count of the milk. In a second study, 91 serial gastric pH measurements were made on 12 preterm infants. pH tended to decrease with increasing age and was significantly lower in infants fed exclusively human milk (2.7 vs. 3.6; human milk versus formula P less than 0.02) We speculate that human milk may influence gastric acid production and thus protect the preterm infant from bacteria in the milk.

Gastric Acid↗
PubMed1985

Controlled trial of furosemide therapy in infants with chronic lung disease.

To study the effects of furosemide therapy in infants with chronic lung disease (CLD), a double-blind controlled trial was designed. Seventeen infants with evidence of CLD (oxygen requirements greater than 30% at greater than 3 weeks of age and chest radiographic findings consistent with CLD) were studied. Pulmonary function was measured immediately before, and after 48 hours and 7 days of treatment with furosemide (1 mg/kg/12 hr intravenously or 2 mg/kg/12 hr orally) or placebo. Clinical status improved in six of seven infants who received furosemide and in two of 10 infants who received placebo (P less than 0.002). In the furosemide group, ventilator and oxygen requirements decreased (P less than 0.003); minute ventilation, alveolar ventilation, and dynamic compliance increased; and venous admixture decreased (P less than 0.05). There were no significant changes in the placebo group. Our findings suggest that furosemide significantly improves lung function during therapy in infants with CLD and allows earlier weaning from ventilatory support and supplemental oxygen.

Chronic Disease↗
PubMed1985

Control of ventilation in subsequent siblings of victims of sudden infant death syndrome.

To learn whether the ventilatory responses to hypoxia (17% O2) and hypercapnea (4% CO2) differ in the subsequent siblings of sudden infant death victims (SIDS), we studied seven normal control infants, nine infants who had had a prolonged apneic spell (apneic infants), and 10 subsequent siblings of SIDS (mean ages 10.4 weeks, 15 weeks, and 10 weeks, respectively). With inhalation of 17% O2, one of seven controls, two of nine apneic infants, and seven of 10 siblings of SIDS breathed periodically (controls vs siblings, P less than 0.04). Heart rate and end-tidal PCO2 did not change, but respiratory rate decreased in the siblings (45 to 31 breaths per minute, P less than 0.001). Arousal occurred during 25% of the hypoxic challenges in the controls and apneic infants but was not seen in the siblings of SIDS (control vs siblings P less than 0.08, apneic vs siblings P less than 0.05). With inhalation of 4% CO2 there was a similar increase in estimated ventilation among the three groups. Arousal occurred 33% of the time in all three groups. Our findings show that, after 5 weeks of age, siblings of SIDS have a normal response to hypercapnea but respond to mild hypoxia with periodic breathing.

Apnea↗
PubMed1985

Neonatal endotracheal flowmeter for tidal volume, airway pressure, and end-tidal gas.

We have designed a new endotracheal flowmeter to measure tidal volume, phasic and mean airway pressures, inspiratory time, and end-tidal PCO2 and PO2 in intubated infants. The flowmeter is light (11 g) and adds minimal dead space (1.0 ml) and resistance (2 cmH2O X 100 ml- X s) to the infant's airway. The volume signal (less than or equal to 10 ml) is linear to 7 Hz, and end-tidal gases can be measured at respiratory rates of 90 breaths/min. This flowmeter is particularly valuable for evaluation of rapid mechanical ventilation of very low birth weight infants.

Airway Resistance↗