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Biomedical subjects

W Conway

Publications and source records attributed to W Conway.

At least 19 recordsLinked to original sources
PubMed1993

Polygalacturonase isozymes from Botrytis cinerea grown on apple pectin.

Five isozymes (four acidic and one basic) of polygalacturonase were separated by chromatofocusing from the culture filtrate of Botrytis cinerea grown on apple pectin. The isozymes, designated as Polygalacturonase I to V, have isoelectric points of 9.7, 4.9, 4.6, 3.7, and 2.7, respectively, with Polygalacturonase III exhibiting the highest specific activity. Polygalacturonase I appeared to function as an endo-polygalacturonase while the other four isozymes act as exo-polygalacturonases. The pH optima of the isozymes range from pH 4.5 to 5.5 with Polygalacturonase V being less sensitive to higher pH compared with the rest of the isozymes.

Chromatography, Thin Layer↗
PubMed1990

Response to CPAP and UPPP in apnea.

Ninety-two consecutive patients with obstructive sleep apnea syndrome (OSAS) were studied before and six weeks after treatment with either nasal continuous positive airway pressure (CPAP) or uvulopalatopharyngoplasty (UPPP) (n = 46 per group). Assignment of patients to treatment was based on clinical considerations and patient preference. Patients were assessed by nocturnal polysomnography and performance on the Multiple Sleep Latency Test (MSLT) the following day. Before treatment, the CPAP and UPPP groups did not differ in sleep-related respiratory disturbance, oxygenation during sleep, fragmentation of sleep, or the level of excessive daytime sleepiness indicated by the MSLT. Both treatments produced significant improvement on all measures. However, improvement in UPPP patients was significantly less consistent than that of CPAP patients. To the extent that UPPP successfully reversed the respiratory disturbance (i.e., 50% reduction in respiratory events index), sleep continuity and daytime sleepiness were improved to a degree comparable to that of patients treated with CPAP.

Female↗
PubMed1989

Effect of mechanical bowel preparation on anastomotic integrity following low anterior resection in dogs.

To assess the effect of mechanical bowel preparation on anastomotic integrity after low anterior resection, 36 mongrel dogs were randomized to have low anterior resection with or without mechanical bowel preparation. All dogs received prophylactic antibiotics and anastomotic integrity was assessed on the ninth postoperative day by barium enema, inspection of anastomoses for defects after careful excision at laparotomy, and anastomotic bursting pressures. Bursting pressures were significantly higher (P less than 0.005) in the group with bowel preparation. Anastomotic defects were present in 13 per cent of animals with bowel preparation and 47 per cent without bowel preparation (P = 0.057). Pelvic abscess and death from peritonitis occurred in 6 per cent of the group with bowel preparation and 29 per cent of the unprepared group. Mechanical bowel preparation significantly enhanced anastomotic integrity and reduced complications in this model.

Anastomosis, Surgical↗
PubMed1989

Predictors of objective level of daytime sleepiness in patients with sleep-related breathing disorders.

Excessive daytime sleepiness, the most prevalent symptom associated with the OSAS, is hypothesized to result from either fragmentation of sleep or hypoxemia during sleep. Measures of nocturnal sleep, respiration during sleep, and daytime sleepiness in 466 patients with apnea were collected to evaluate these two hypotheses. The various parameters were submitted to correlation and multiple regression analyses to predict daytime sleepiness as measured by the MSLT. The RAI, which measures the number of arousals from sleep associated with respiratory disturbances (best fragmentation correlation), produced a higher correlation with MSLT scores than did TMES (best hypoxemia correlation); however, the measures were highly intercorrelated, and multiple regression analyses to determine which parameters independently predicted MSLT showed the single best predictor to be the RAI. Additional independent variance in MSLT score was explained by TST and PSG1. Measures of hypoxemia provided little or no independent predictive information. These data support the hypothesis that sleep fragmentation is an important determinant of daytime sleepiness in patients with apnea.

Female↗
PubMed1988

Mortality and apnea index in obstructive sleep apnea. Experience in 385 male patients.

Although obstructive sleep apnea (OSA) has been studied in detail for over a decade, the mortality of this disorder is unclear. We calculated cumulative survival in 385 male OSA patients. We found that those with an apnea index (AI) greater than 20 had a much greater mortality than those with AI = less than 20. The probability of cumulative eight-year survival was .96 +/- 0.02 (SE) for AI = less than 20 vs. 63 +/- 0.17 for AI greater than 20 (p less than .05). This difference in mortality related to AI was particularly true in the patients less than 50 years of age in whom mortality from other causes is not common. None of the patients treated with tracheostomy or nasal CPAP died. Eight of the patients treated with uvulopalatopharyngoplasty (UPPP) died and the cumulative survival of the UPPP-alone treated group was not different from the survival curve of untreated OSA patients with an apnea index of greater than 20. We conclude that OSA patients with an apnea index of greater than 20 have a greater mortality than those below 20 and that UPPP patients be restudied after therapy. If the latter patients are found not to have marked amelioration of their AI, then they should be treated by nasal CPAP or tracheostomy.

Actuarial Analysis↗
PubMed1987

Hypercapnia and sleep O2 desaturation in chronic obstructive pulmonary disease.

There is a wide clinical spectrum in chronic obstructive pulmonary disease (COPD). The extremes of this spectrum, the "pink puffer" (PP) and "blue bloater" (BB) stereotypes differ in their degree of sleep hypoxemia and pulmonary hypertension. Most patients cannot be characterized as either PP or BB. The data amassed in the recent nocturnal oxygen therapy trial provide an opportunity to see to what extent differences in sleep oxygenation and hemodynamics in a large hypoxemic COPD population are related to awake hypoxemia and hypercapnia. From a large hypoxemic COPD population sleep SaO2 was examined in those with (PaCO2 greater than 44 mm Hg) and without (PaCO2 less than or equal to 44 mm Hg) hypercapnia. Hypercapnic patients (mean PaCO2 49.8 mm Hg) had the same PaO2 and degree of airflow obstruction as normocapnic patients (PaCO2 37.4 mm Hg) but had far greater sleep hypoxemia (measured by mean sleep SaO2, low sleep SaO2, and awake-low sleep SaO2, p less than 0.05). In addition, arterial blood gases of the large sleep O2 desaturaters were compared with those of the small desaturaters; PaO2 was similar in both groups, whereas PaCO2 was different (p less than 0.01). Two common subsets of hypoxemic patients were also compared; one was hypercapnic and overweight, the other normocapnic and hyperinflated. We found that patients in the hypercapnic group had far worse sleep hypoxemia, although they had better lung function. We conclude that hypercapnia is a marker for sleep O2 desaturation in hypoxemic COPD.

Aged↗
PubMed1986

Lack of bacterial aerosols associated with heat and moisture exchangers.

Contaminated condensate might serve as a source for cross infection. Heat and moisture exchangers (HME) are devices that humidify inspired gases, which pass through a hygroscopic felt pad surrounded by a cellulose sponge housed in a plastic case. In our study, we used a Servo 150 HME in place of a cascade humidifier in mechanical ventilator circuits. We performed 2 studies to evaluate the microbiologic safety of the HME. First, 42 HMEs used by patients for 24 h were tested in the laboratory for contamination. To simulate patient/air exchange, the HMEs were connected to the Andersen Sampler (flow at 35 L/min x 20 min). Although the inner felt pad of the HMEs was contaminated in 74% of the units (31 of 42), only 4.8% (2 of 42) generated 1 to 2 bacteria/702 L of air. In a second study, HMEs contaminated with either Staphylococcus aureus or Pseudomonas aeruginosa (at 10(3), 10(5), or 10(8) organisms/ml) were connected to an Andersen Air Sampler to simulate a ventilator circuit. Bacterial aerosols were not generated, with the exception of 2 to 4 bacteria recovered after contamination with 10(8) bacteria. The HME can provide humidification for mechanically ventilated patients with little risk of generating respirable bacterial aerosols.

Aerosols↗
PubMed1985

Pharmacological effects of sedative-hypnotics, narcotic analgesics, and alcohol during sleep.

This article briefly reviews the well known effects of sedative-hypnotics, alcohol and narcotics on sleep. These drugs also have respiratory depressant effects, and the limited information about their effects on sleep-related breathing disturbances is reviewed. They exacerbate obstructive sleep apnea syndrome and have moderate to minimal effects on occasional apnea or hypopnea, but do not induce breathing disturbances de novo.

Adult↗
PubMed1985

Sleep-wake complaints in patients with sleep-related respiratory disturbances.

The relation of sleep complaint to sleep continuity and respiratory disturbance was studied by comparing 2 series of patients with sleep apnea, one group complaining of insomnia and the other of excessive daytime sleepiness. On polysomnographic evaluation, patients with insomnia complaints had fewer and shorter, primarily central, apneas that had little hypoxemic effects. Patients with excessive sleepiness complaints had more and longer, primarily obstructive, apneas that produced significant hypoxemia. Sleep of the excessively sleepy patients was lighter and longer, whereas that of the patients with insomnia was characterized by more wake time before and after sleep onset. The excessively sleepy patients were objectively sleepy on a test of daytime sleepiness, whereas patients with insomnia were alert.

Adult↗
PubMed1985

Uvulopalatopharyngoplasty. One-year followup.

Uvulopalatopharyngoplasty (UPPP), originally evaluated in 66 patients with objectively documented sleep apnea syndrome, was successful in 33 of the patients as indicated by clinical and polysomnographic improvements. One-year followup polysomnographic evaluations were obtained in 20 of these patients; the remaining 13 were lost to followup. After one year, the patients maintained the improvements seen at the six-week evaluation. Frequency and duration of apnea was significantly reduced from presurgery levels and similar to the six-week results. Oxygenation measures also did not differ from the six-week results, remaining better than presurgery values. Thus, respiration did not disrupt sleep to the degree it had before surgery. Sleep measures were improved compared to presurgery and similar to the six-week data. Body weight remained stable over the entire period.

Female↗