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Biomedical subjects

B J Koos

Publications and source records attributed to B J Koos.

44 records · Page 3Linked to original sources
PubMed1986

Fetal breathing movement, sleep state and cardiovascular responses to an inhibitor of mitochondrial ATPase in sheep.

Hypoxia abolishes breathing movements in fetal sheep, perhaps by reducing ATP synthesis within regulatory brain cells. This possibility was examined by administering to 13 chronically catheterized fetal sheep oligomycin B, a mitochondrial ATPase inhibitor. Injections into the left external carotid artery of oligomycin B (170 +/- 19 micrograms/kg in 9 fetuses) reduced significantly (P less than 0.01) the incidence of fetal breathing movements from a control mean of 52 +/- 6.3% to 6 +/- 2.2 and 9 +/- 4.4% during the first and second hours after drug injection. Oligomycin did not decrease significantly the incidence of low voltage electrocortical activity or reduce the average duration of a cycle of low and high voltage electrocortical states. Nor did it decrease significantly the incidence of rapid eye movements. Fetal heart rate and mean arterial pressure were not significantly affected, and the arterial blood gases and pH did not significantly differ from control values. However, a large dose of the drug (700 micrograms/kg) produced an isoelectric electrocorticogram, hypertension, and bradycardia associated with a rise in arterial PO2 and a severe metabolic acidosis. In 3 fetal sheep oligomycin also inhibited continuous breathing induced by indomethacin. Injection of the vehicle (ethanol) alone did not alter the incidence of breathing movements, electrocortical activity, eye movements or blood gases. These results suggest that reduced mitochondrial production of ATP may be a mechanism by which hypoxia abolishes fetal breathing activity.

Adenosine Triphosphatases↗
PubMed1986

Effects of moderate hypoxia on fetal electrocortical activity, eye movements, and breathing activity in sheep.

Isocapnic hypoxaemia (delta PaO2 = -8.0 +/- 0.5 mmHg; delta CaO2 = -2.86 +/- 0.20 ml/dl) was produced in fetal sheep by having the ewe breathe for one hour a gas mixture (v/v) of 10.5% O2 and 1.5% CO2 in N2. Mean fetal heart rate, blood pressure, and incidence of low voltage electrocortical activity were not affected. However, the incidence of rapid-eye-movements and breathing activity was reduced by about 40%. Breathing movements during hypoxaemia had a mean inspiratory time, breath interval, and tracheal pressure amplitude which did not differ significantly from those during control experiments in which the ewe breathed air from the plastic bag. These observations suggest that hypoxia decreases the incidence of breathing movements but does not affect the amplitude or pattern of breathing activity and that it may reduce the incidence of eye movements and breathing activity through a common mechanism.

Animals↗
PubMed1985

Is there a need for digital examination in patients with spontaneous rupture of the membranes?

A prospective comparison between digital and visual speculum examination was made in 133 pregnant patients. The coefficient correlation between the two examinations of effacement and dilation of the cervix was 0.74. The present results suggest that cervical evaluation by means of speculum examination in the assessment of pregnant patients with spontaneous rupture of membranes are adequate.

Cervix Uteri↗
PubMed1985

Central stimulation of breathing movements in fetal lambs by prostaglandin synthetase inhibitors.

In unanaesthetized fetal lambs at 125-135 days gestation in utero central acidosis caused by perfusion of the cerebral ventricular system with a solution containing less than 1 mM-HCO3- (cerebrospinal fluid (c.s.f.) pH 6.98) or intravenous infusion of ammonium chloride (c.s.f. pH 7.1) produced an increase in the depth and frequency of episodic breathing but no change in electrocortical activity, heart rate or arterial pressure. Administration of prostaglandin synthetase inhibitors, sodium meclofenamate (0.8-10 mg/kg I.V. or 0.6-2.6 mg/kg intracerebrally) or acetylsalicylic acid (6.7 mg/kg I.V.) caused prolonged episodes of fetal breathing during low and high voltage electrocortical activity, with a large increase in breath amplitude. Blood gas values, heart rate, blood pressure, electrocortical activity and eye movements were not altered. In fetuses whose brain stems had been sectioned in the upper pons or the inferior colliculus, sodium meclofenamate induced prolonged deep breathing. Intravenous prostaglandin E2 abolished the continuous breathing induced by meclofenamate, but not breathing movements enhanced by hypercapnia or hypoxia. It is concluded that the central chemoreceptors respond to acidosis in near-term lamb fetuses qualitatively as in adult animals. Secondly, the results suggest that prostaglandin E2 and the inhibitors of prostaglandin synthesis also act centrally in the lower pons or medulla to modulate fetal breathing.

Ammonium Chloride↗
PubMed1976

Mercury toxicity in the pregnant woman, fetus, and newborn infant. A review.

This paper reviews the reported cases of mercury poisoning in pregnancy and the data based on sources of contamination, maternal uptake, and distribution. It analyzes current knowledge of placental transfer of various mercury compounds, fetal uptake, and distribution. It identifies the embryopathic and fetal toxic effects of mercury in general while emphasizing the greater toxicity of methylmercury compounds. Since maternal exposure to methylmercury is primarily through fish consumption, it recommends that women of childbearing age should not consume more than 350 Gm. of fish per week. In addition, they should not be occupationally exposed to air concentrations of mercury vapor greater than 0.01 mg. per cubic meter, of inorganic and phenylmercuric compounds greater than 0.02 mg. per cubic meter, or any detectable concentration of methylmercury.

Abnormalities, Drug-Induced↗
PubMedDate not supplied

Predictive value of HemoCue capillary whole blood glucose measurements in pregnancy.

OBJECTIVE: We determined the ability of capillary whole blood glucose concentrations to predict venous plasma and whole blood glucose levels. METHODS: During a standard oral glucose tolerance test in 29 pregnant women, paired capillary and venous blood samples were collected for analysis of glucose concentrations by the HemoCue photometer and by central laboratory methods. RESULTS: Glucose concentrations determined serially in a single blood sample by the HemoCue method were highly reproducible, with a coefficient of variation of 2.3%. However, glucose levels in blood from two different fingersticks from the same patient varied on average by 3 mg/dL, with a maximum difference of 14 mg/dL. Although capillary whole blood glucose results obtained by the HemoCue method correlated well with venous plasma or whole blood glucose measurements (r = 0.98 and r = 0.97, respectively) over the range investigated (60-250 mg/dL), individual capillary whole blood glucose measurements were only a fair predictor of venous values, with 95% of measured venous levels within +/- 26 mg/dL and +/- 20 mg/dL for concentrations predicted for plasma and whole blood, respectively. CONCLUSION: Sampling factors rather than measurement accuracy limit the ability of capillary whole blood glucose measurements to predict venous concentrations.

Blood Glucose↗