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Biomedical subjects

S McGhee

Publications and source records attributed to S McGhee.

7 recordsLinked to original sources
PubMed1994

Obstructive sleep apnea in obese noninsulin-dependent diabetic patients: effect of continuous positive airway pressure treatment on insulin responsiveness.

Patients with noninsulin-dependent diabetes mellitus (NIDDM) are often obese and frequently complain of tiredness. These features are also characteristically seen in patients with obstructive sleep apnea (OSA). Therefore, it was the aim of this study to assess the prevalence of OSA among a group of obese NIDDM patients who have some clinical features of OSA. The effect of reversal of OSA by nasal continuous positive airway pressure (CPAP) treatment on insulin responsiveness was also investigated. From a population of 179 NIDDM patients with a body mass index (BMI) greater than 35 kg/m2, we performed ambulatory sleep monitoring on 31 (15 males and 16 females) who admitted to either heavy snoring or excessive sleepiness. Results were reviewed by a sleep physician blinded to the clinical status of the patients, and 22 (70%) were found to have moderate or severe OSA, with mean oxygen desaturation indexes of 10.3 +/- 5.3 and 30.7 +/- 13.2 episodes/h, respectively. A subgroup of 10 patients (seven males and three females) with a mean BMI of 42.7 +/- 4.3 kg/m2 was treated with nightly CPAP for 4 months. These subjects all had significant OSA, with frequent obstructive apneas (mean, 47 +/- 31.6 episodes/h) and oxygen desaturation (mean minimum O2 saturation, 74 +/- 9.5%), as determined by polysomnography. One patient was excluded from analysis because of infrequent use of CPAP. Insulin responsiveness in terms of glucose disposal measured by hyperinsulinemic euglycemic clamps improved from 11.4 +/- 6.2 to 15.1 +/- 4.6 mumol/kg.min (P < 0.05) during CPAP treatment. These results indicate that OSA occurs commonly in obese NIDDM patients with excessive sleepiness or heavy snoring. Treatment of their OSA may improve insulin responsiveness.

Adult↗
PubMed1994

Permeabilization, staining and culture of living Drosophila embryos.

The organic solvent octane has been used routinely to permeabilize the hydrophobic vitelline membrane surrounding the Drosophila embryo, thereby allowing the movement of small molecules into the egg. We present evidence that hexane is a more effective permeabilizing agent than octane and compare the effects of these solvents on uniformity of permeabilization and embryonic viability. The ability of each solvent to make the embryo accessible to a range of biological stains was compared. The effect of octane versus hexane permeabilization on subsequent embryonic viability was measured at seven different stages during early embryogenesis. We found that although hexane is a superior solvent for permeabilizing the vitelline membrane, it decreases the viability of embryos exposed between 0 and 3 hr of age. Older embryos treated with either hexane or octane are usually viable. We also showed that molecules with a molecular mass of 984 Daltons or more did not diffuse into the embryo following treatment with either hexane or octane. Results presented here challenge a phase-partition model that has been proposed previously to explain the molecular basis of permeabilization of the Drosophila egg. An alternative model is described as well as an optimized protocol for permeabilizing and staining Drosophila embryos at any stage during early embryogenesis while maintaining viability for subsequent culture.

Animals↗