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Biomedical subjects

G Martens

Publications and source records attributed to G Martens.

At least 55 records · Page 3Linked to original sources
PubMed1978

Fetal effects of cervical ripening with extra-amniotic prostaglandin E2 in gel.

A gel containing 0.5 mg prostaglandin E2 (PGE2) was extra-amniotically instilled 90 clinically normal gravidae at term, for ripening of the cervix before elective induction of labor by amniotomy and intravenous PGE2. An acceptable increase in the Bishop score was noted to have occurred in 87/90 women, when assessed eight hours after administration of the gel; 14 of these women were then in established labor, which progressed uneventfully. Four of the 90 subjects required cesarean section for cephalopelvic disproportion. No adverse maternal or fetal effects of the procedure were detected under careful clinical, electronic and biochemical monitoring. However, epidural anesthesia adversely influenced the acid-base equilibrium of the fetus.

Acid-Base Imbalance↗
PubMed1978

Extra-amniotic prostaglandin F2alpha in gel for prelabor cervical ripening.

In 22 normal term gravidas with unfavorable cervix, 5 mg PGF2alpha in Tylose gel was instilled into the extra-amniotic space. The treatment improved the cervical state so much that the women could be successfully induced by conventional methods. The procedure was well tolerated by the mother and it appeared to be perinatally safe.

Cervix Uteri↗
PubMed1977

Elective induction of labor conducted under lumbar epidural block. I. Labor induction by amniotomy and intravenous oxytocin.

Epidural analgesia (bupivacaine) was administered during labor after amniotomy, in some cases supplemented by intravenous oxytocin. A higher incidence of transient uterine hypertonus was seen after blocking. Fetal heart rate changes mainly took the form of bradycardia (in association with uterine hypertonus). At birth, the maternal biochemical condition was characterized by a lower degree of metabolic acidosis, compared to normal unanesthetized controls. The fetuses displayed a slight degree of hypoxia and hypercapnia. The mechanisms underlying these modifications are discussed. Epidural blockade in combination with elective induction of labor, whether or not supplemented by intravenous oxytocin, may carry a risk. Its magnitude is considered acceptable for both mother and fetus provided they are constantly under close surveillance, limited amounts of bupivacaine are administered and the second stage of labor is kept short. However, some warnings against epidural analgesia apply to patients with placental insufficiency and very active labor.

Adult↗
PubMed1977

Elective induction of labor conducted under lumbar epidural block. II. Labor induction by amniotomy and intravenous prostaglandin.

Labor was electively induced at term in 117 clinically normal nulliparae and parous women by combining low amniotomy with intravenous administration of prostaglandin F2 alpha (n = 64) or prostaglandin E2 (n = 53). Analgesia was obtained by continuous lumbar epidural block with bupivacaine. The procedure was very effective in producing vaginal delivery within 24 h after prostaglandin infusion (n = 115), but it was accompanied by an extremely high incidence of uterine hypertonus. Tentative explanations for the transient uterine hyperstimulation are a direct stimulatory effect of the local anesthetic on the contractility of the myometrial fiber and/or a temporarily higher amount of circulating oxytocic compound reaching the myometrium due to local vasodilatation as a result of sympathetic nerve blockade. In some cases uterine hypertonus was associated with slowing of the basal fetal heart rate and, when severe, with the appearance of late deceleration patterns and fetal acidosis. In other cases the fetal heart rate deceleration is explained by the toxic effect of bupivacaine on the myocard. Since both the myometrial hyperactivity and the FHR alterations were temporary, fetal biochemical parameters were unaffected at completion of the first stage of labor. Because with intravenous prostaglandin uterine hyperstimulation is more difficult to avoid and regional analgesia further increases the hazard of both hypertonus and fetal heart rate deceleration, the combined application of an intravenous prostaglandin and continuous epidural analgesia should not be introduced into obstetrical practice.

Adult↗
PubMed1977

A comparison of buccal (oromucosal) and oral prostaglandin E2 for the elective induction of labor.

In 100 clinically-normal women, labor was induced at term by low amniotomy and PGE2. The drug was administered by either the oral or the oromucosal route, the same incremental dose scheme (initial dose of 0.5 mg; hourly increment of 0.5 mg until adequate uterine stimulation or a maximum single dose of 3.0 mg) being applied. Both routes of administration had comparable efficacy and were equally safe. The incidence of abnormal monitoring findings (uterine hypertonus, transient bradycardia and dips II during the first stage; late decelerations, progressive and transient bradycardia during the second stage of labor) and of low Apgar scores were similar. Acid-base and lactate-pyruvate equilibria in mother and fetus were not influenced by the route of drug administration in parous women. In nulliparae treated with PGE2 by the oromucosal route, higher values were found for the fetal-maternal difference in excess lactate than in those given oral PGE2; however, this is probably of little clinical importance.

Administration, Oral↗
PubMedDate not supplied

Fetal Doppler flow measurements in the early second trimester: a correlation with fetal outcome.

In 31 women with a singleton pregnancy, abdominal duplex doppler examinations were performed at W16-W17, W26 (+/- 2 weeks) and W34 (+/- 2 weeks) in order to study the flow velocity wave (FVW) indices in the early second trimester and their predictive value for fetal outcome. 24 women with a normal pregnancy outcome were considered as the reference group. In the early second trimester, end-diastolic block occurs frequently at the 150 Hz thump filter setting (15/24 in the fetal descending aorta, 19/24 in the umbilical artery). At the 50 Hz filter setting, end diastolic block appeared in 1/24 cases in the aorta and in 2/24 cases in the umbilical artery. The finding did not persist throughout pregnancy. The flow-velocity indices in the early second trimester in the small-for-dates were comparable to the normal group. We conclude that high peripheral resistance is a common finding in the fetal circulation in early pregnancy. It is not predictive of subsequent growth retardation.

Aorta↗
PubMedDate not supplied

Bioactivation of tetrachloroethylene. Role of glutathione S-transferase-catalyzed conjugation versus cytochrome P-450-dependent phospholipid alkylation.

The metabolism of [14C]tetrachloroethylene (Tetra) and its metabolite S-(1,2,2-trichlorovinyl)-L-cysteine (TCVC) was investigated with in vitro systems to substantiate metabolic pathways of Tetra deduced from in vivo experiments. In the presence of NADPH, rat hepatic microsomal fractions metabolized Tetra to soluble metabolites, which were identified as trichloroacetic acid and oxalic acid by gas chromatography/mass spectroscopy and a metabolite largely bound to microsomal macromolecules. The majority of the alkylated macromolecules were identified as N-trichloroacetylated phospholipids by high performance liquid chromatography and GC/MS. When Tetra was incubated with hepatic microsomes and cytosol in the presence of 10 mM glutathione, but in the absence of NADPH, the formation of a polar metabolite other than trichloroacetic acid and oxalic acid was observed. This metabolite was identified, after hydrolysis to the corresponding cysteine conjugate, as S-(1,2,2-trichlorovinyl)-glutathione (TCVG). Microsomal GSH S-transferases catalyzed TCVG formation more efficiently than cytosolic GSH S-transferases; the competitive substrate 1-chloro-2,4-dinitrobenzene inhibited TCVG formation. In the presence of both NADPH and GSH, TCVG formation in microsomes was decreased, indicating that oxidative metabolism and GSH conjugation of Tetra are competitive reactions. The Tetra metabolite TCVC was cleaved by bacterial cysteine conjugate b-lyase to dichloroacetic acid and pyruvate. The obtained results substantiate the postulated pathways of Tetra biotransformation and demonstrate that both oxidative and conjugative reactions occur in hepatic Tetra metabolism. Phospholipid alkylation, which occurs during oxidative metabolism, may be a deactivation reaction, whereas TCVG formation, renal metabolism to TCVC, and cleavage of TCVC by b-lyase under formation of mutagenic intermediates may contribute to the nephrocarcinogenic effect of Tetra.

Alkylation↗