Biomedical subjects

J Fleetham

Publications and source records attributed to J Fleetham.

23 records · Page 2Linked to original sources

PubMed1986

In vivo human tracheal pressure-area curves using computerized tomographic scans. Correlation with maximal expiratory flow rates.

In order to develop a simple technique to measure in vivo pressure-area (P-A) curves of the extrathoracic trachea in humans, we studied 14 normal male subjects. Valsalva and Mueller maneuvers were performed at FRC, and tracheal cross-sectional area (TXSA) was measured using computed tomography. Extrathoracic tracheal transmural pressure (TMP) was obtained as airway opening minus atmospheric pressure (Pat). Tracheal "compliance" (TC) was measured on the "inflation" limb of the P-A curve. Tracheal compliance was not a significant predictor of maximal expiratory flow rates, and TXSA at zero TMP was a significant predictor of peak expiratory flow rate but not of FEV1 or Vmax50. P-A curves showed an unexpected configuration characterized by a plateau or an increase in TXSA with TMP lower than -15 cm H2O. P-A curves obtained in 5 subjects using extrathoracic esophageal pressure as tracheal external pressure instead of atmospheric pressure did not show a plateau or an increase in TXSA with Mueller maneuvers. In these 5 subjects, TC using esophageal pressure rather than Pat did not aid in the prediction of flow. We conclude that extrathoracic tracheal external pressure is not Pat because this pressure is probably affected by transmission of pleural pressure to the cervical interstitial tissue as well as by the contraction of cervical accessory inspiratory muscles. Therefore, true tracheal compliance cannot be simply measured since it requires placement of an esophageal balloon.

Adult↗

PubMed1986

Chromosomal analysis of unfertilized human oocytes.

Unfertilized human oocytes were obtained from women in an in-vitro fertilization programme. The women had a mean age of 29.4 years (range 24-35 years). Chromosomal complements could be analysed in 50 oocytes. Q-banding of the chromosomes facilitated identification of individual chromosomes: 34 oocytes (68%) had the normal haploid chromosomal complement, 14 complements were hypohaploid (28%), 1 complement was hyperhaploid (2%) and 2 had structural abnormalities (4%). (One oocyte had numerical and structural abnormalities). The 16 abnormal oocytes were obtained from 15 different women. A conservative estimate of aneuploidy in this sample is 4%; however, the frequency of aneuploidy may be higher if there is a predisposition to chromosome loss during oogenesis. This study provides information on the largest series of karyotyped unfertilized human oocytes published to date.

Adult↗

PubMed1982

Sleep, arousals, and oxygen desaturation in chronic obstructive pulmonary disease. The effect of oxygen therapy.

In order to assess the role of hypoxemia in the sleep disruption of patients with COPD, we studied patients breathing air and oxygen during sleep. In 24 patients with COPD, we determined the 95% confidence bands for arterial O2 saturation (SaO2) in the various sleep stages. The lowest mean SaO2 was during REM sleep. Patients spent 22.4% of the night desaturated (SaO2 more than 5% below awake SaO2). Apneic episodes were uncommon and occurred in only 2 patients. When compared with established age-matched normal subjects from another center, poor sleep quality was indicated by reduced sleep time, increased sleep stage changes, and increased arousal frequency. Oxygen therapy had no apparent effect on sleep quality. Arousal frequency was independent of measurements of awake pulmonary function or chemical control of breathing. During room air breathing, arousals were strongly associated with periods of arterial oxygen desaturation. However, relief of the hypoxemia with supplemental oxygen had no effect on arousal frequency. This suggests that it is not hypoxemia per se, but an associated phenomenon such as hypercapnia that causes the arousals.

Aged↗

PubMedDate not supplied

Relationship of a human oocyte scoring system to oocyte maturity and fertilizing capacity.

A simple, quick, and semiquantitative human oocyte scoring system is described. Oocyte-corona-cumulus complexes were spread, either by tilting the dish or by aspiration of the fluid, and examined under the dissecting microscope. A maximum of four points was assigned to each of the following: cumulus expansion, cumulus appearance, amount of cumulus, corona expansion, corona appearance, and oocyte appearance. The oocyte score was significantly correlated to two important physiological parameters of oocytes, nuclear maturity (P less than .02) and fertilization rate (P less than .0001). This oocyte scoring system is useful for selecting oocytes for in vitro fertilization and embryo transfer (IVF-ET) or gamete intrafallopian tube transfer (GIFT), for training new laboratory personnel in recognizing the important characteristics of a mature oocyte, and in the standardized reporting of oocyte quality by different IVF-ET or GIFT programs.

Clomiphene↗

PubMedDate not supplied

Simplified LH-rise method to time oocyte recovery for in vitro fertilization.

The aim of this study was to assess the usefulness of a simplified method to detect the LH rise. The mean plus two standard deviations of the LH values in the prevulatory period was 6.70 +/- 3.45 mIU/mL in a group of women in whom at least one mature oocyte fertilized and cleaved. For practical purposes, an absolute LH value of 15 mIU/mL was considered the start of the rise using the LH graph, and was designated the LH rise value. In 76 patients who experienced a spontaneous LH surge (detected by daily sampling at 08:00, 15:00, 23:00), oocyte recovery was timed for 32 to 35 hours after the LH rise using this simplified method. The outcome of IVF-ET in these patients was comparable to that of the control patients in whom hCG was administered. Graphs were drawn retrospectively using only two (08:00 and 23:00) LH values obtained for each day for each patient and the start of the LH rise was plotted. Most patients (66%) would have had oocyte recovery at the same time whether they had two or three daily LH values. The remaining patients would still have undergone oocyte recovery at an acceptable time (within +/- 6 hours). It was concluded that this simple method accurately identifies the onset of the spontaneous LH rise and may be effected by twice-daily LH sampling.

Circadian Rhythm↗