Search PubMed⌕ Search

Biomedical subjects

B Langer

Publications and source records attributed to B Langer.

At least 55 records · Page 3Linked to original sources
PubMed1999

Temperature calibration under ultrafast MAS conditions

For conventional fast magic-angle spinning (MAS) frequencies (</=15 kHz), there is a known heating of the sample due to the friction between the rotor and the bearing gas. At the recently achievable ultrafast MAS frequencies of up to 35 kHz, a more dramatic heating effect is expected. Using the 119Sn NMR signal of the chemical shift thermometer Sm2Sn2O7, this frictional heating effect is quantified, and a calibration of the sample temperature under ultrafast MAS conditions is described. An empirical expression is given which allows the determination of the sample temperature as a function of the bearing gas temperature and the spinning frequency. Copyright 1999 Academic Press.

Journal Article↗
PubMed1999

Routine prenatal care in Europe: the comparative experience of nine departments of gynaecology and obstetrics in eight different countries.

OBJECTIVE: The aim of this study was to compare routine prenatal care in nine European obstetrics and gynaecology departments. STUDY DESIGN: A survey was performed between October 1992 and November 1993 by means of a questionnaire. The questionnaire comprised 118 questions covering clinical examinations and investigations systematically performed during the pregnancy. RESULTS: The survey revealed a certain number of differences between the types of prenatal care performed by each department. Thus, one notices differences to do the serological testing (toxoplasmosis, AIDS and hepatitis B) at the first visit and in the practice of vaginal examination, systematic ultrasound examination or cardiotocography. CONCLUSION: The differences observed in the prenatal care furnished are only a reflection of our uncertainties concerning the validity of the various tests used to monitor pregnancies. At a time when financial restrictions impose choices, we consider an evaluation of the efficacy and cost of prenatal care to be essential.

Acquired Immunodeficiency Syndrome↗
PubMed1999

[Clinical importance of fetal pulse oximetry. I. Methodological evaluation. Multicenter study. French Study Group on Oximetry of Fetal Pulse].

OBJECTIVE: To evaluate the feasibility of intrapartum fetal pulse oximetry, the distribution of fetal oxygen saturation values, and the relation with the neonatal outcome in a population with an abnormal fetal heart rate (FHR). STUDY DESIGN: A prospective multicenter observational study, from June 1994 to November 1995. Fetal oxygen saturation was continuously recorded using a Nellcor N-400 fetal pulse oximeter in case of abnormal FHR during labor. Simultaneous readings of fetal oxygen saturation and of fetal blood analysis (FBA) were obtained at inclusion and before birth. Feasibility, adverse effects, distribution of fetal oxygen saturation values and relation with neonatal outcome were assessed. RESULTS: 74 patients were included. From 172 attempted sensor placements, the procedure was impossible in three cases and fetal oxygen saturation values were obtained in 164 cases (95.3%). Physicians considered sensor placement an easier task than FBA attempt (easy in 87.5% vs 78.9% for FBA, p = 0.03). The mean reliable signal time (+/- SD) was 64.7 +/- 32% during the first stage. There were no serious adverse effects in the study population. The mean fetal oxygen saturation during the first stage of labor was 42.2 +/- 8.0% (10th-90th centile range: 30-53%). Fetal oxygen saturation was significantly correlated with scalp pH (r = 0.29; p = 0.01) but not with neonatal umbilical artery pH or gas values. There was a significant association between a low fetal oxygen saturation (< 30%) and a poor neonatal condition. CONCLUSION: The feasibility of fetal pulse oximetry is satisfactory in clinical practice. It is easy to use and provides a fair rate of recorded values, even in a population with suspicion of fetal distress. A low fetal oxygen saturation is significantly associated with an abnormal neonatal outcome.

Adult↗
PubMed1999

[Clinical importance of fetal pulse oximetry. II. Comparative predictive values of oximetry and scalp pH. Multicenter study].

OBJECTIVE: To compare the predictive value of intrapartum fetal pulse oximetry to that of fetal blood analysis for an abnormal neonatal outcome in case of abnormal fetal heart rate (FHR). STUDY DESIGN: A prospective multicenter observational study, from June 1994 to November 1995. Fetal oxygen saturation was continuously recorded using a Nellcor N-400 fetal pulse oximeter in case of abnormal FHR during labor. Simultaneous readings of fetal oxygen saturation and fetal blood analysis obtained before birth, i.e. either at full dilatation, or before cesarean section when indicated, were compared with the neonatal status. The criteria for an abnormal neonatal outcome were 1) an umbilical arterial blood pH < or = 7.15 and 2) a combined variable including: 5 min. Apgar score < or = 7, umbilical arterial pH < or = 7.15, secondary respiratory distress, transfer in a neonatal care unit, or neonatal death. RESULTS: At a 7.20 threshold for fetal scalp pH, and 30% for fetal oxygen saturation (i.e. the tenth centile in the study population), the predictive value of fetal pulse oximetry was similar to that of fetal blood analysis for an arterial umbilical pH < or = 7.15, and for an abnormal neonatal outcome (positive predictive value 56% vs 55%, negative predictive value 81% vs 82%, sensitivity 29% vs 35%, and specificity 93% vs 91% respectively). The receiver operating curve showed similar performance of either technique for cut-off values < or = 7.20 for fetal blood pH and < or = 30% for fetal oxygen saturation, whereas fetal pulse oximetry became superior at higher thresholds. CONCLUSION: The predictive value of intrapartum fetal pulse oximetry can be favorably compared with that of fetal blood analysis. Randomized controlled management trials can now be performed to assess potential clinical benefits of this new tool.

Female↗
PubMed1999

[Prenatal and neonatal management of digestive tract duplications. Diagnostic difficulties and therapeutic implications].

OBJECTIVE: To insist on the difficulty of the antenatal diagnosis of digestive duplications, to show the importance of a complete malformative screening, and the need for immediate management at birth. MATERIAL AND METHODS: A cystic duplication of the tongue, a duplication, abdomino-thoracic transdiaphragmatic, and a duplication of the small bowel are described and compared with cases previously reported in th literature. RESULTS: Antenatal evacuation puncture of a duplication of the tongue must be reserved for exceptional situations. Foregut duplications are often associated with other malformations. The duplication of the small intestine can exceptionally expose to a mechanical complication, mostly during the postnatal period, which may require emergency surgery. CONCLUSION: Duplications of the alimentary tract should be detectable on prenatal ultrasound examination. A complete antenatal malformative screening is required and in utero transfer is warranted because emergency surgery may be required.

Abnormalities, Multiple↗
PubMed1999

[Massive feto-maternal transfusion. Report of 3 cases with review of the literature].

Massive feto maternal hemorrhage is rare. Early diagnosis is important because massive feto-maternal hemorrhage has a poor prognosis. The clinical manifestations of transplacental hemorrhage are related not only to the size of the hemorrhage but also to the time at which the hemorrhage occurs. In women who are candidates for Rh immune prophylaxis, massive feto maternal hemorrhage may be detected by Kleihauer test and we suggest that 10 micrograms dose of immune globin should be administered for each estimated ml of Rh positive blood given, to prevent an immunization Disappearance of fetal cells by Kleihauer test or appearance residual antibody suggests the adequacy of therapy. Three cases of massive fetomaternal hemorrhage (more than 225 ml) are presented here. Two mothers was Rh negative and they are delivered of rhésus positive children, which necessitated the administration of large volume of anti D. One of the cases shows the possibility of association between choriocarcinoma and positive kleihauer test.

Adult↗
PubMed1999

Two cases of Townes-Brocks syndrome.

Townes-Brocks syndrome (TBS) has been recognized as a dominant inherited syndrome. We report 2 cases of TBS. Case 1 was operated on for imperforate anus. Triphalangeal thumb and ear anomalies were remarkable. Deafness was diagnosed when the patient was 6 months old. Anomalies of the semicircular canals and the incus with inculomalleolar fusion were shown when the patient was 3.5 years old. During childhood, recurrent episodes of abdominal pain appeared. The diagnosis of hereditary angioneurotic edema (HANE) was made. HANE was familial as the father, the father's brother and the paternal grand mother were also affected. The parents of case 2, a female, are both mildly mentally retarded. This was the first pregnancy of the mother who had short stature. The child had an antepositioned anus, bifid right thumb, large toes, low set ears, microretrognathia and deafness. A (5, 16) translocation was observed in a child with TBS. At the breakpoint in 16q21.1, a gene coding for a transcription factor SALL1 has been identified and it was shown that mutations in the putative zinc finger of SALL1 cause TBS.

Abnormalities, Multiple↗
PubMed1998

The behavior of substrate analogues and secondary deuterium isotope effects in the phenylalanine ammonia-lyase reaction.

Metacresol and glycine can be thought as a dissection of metatyrosine, which is an excellent substrate of phenylalanine ammonia-lyase (PAL) (B. Schuster and J. Rétey, PNAS 92, 8433, 1995). Whereas metacresol was a very weak inhibitor and glycine was inert, simultaneous addition of both compounds led to synergistic inhibition of PAL. [2H5]Phenylalanine as a substrate showed a kinetic deuterium isotope effect of 9% (kH/k2H = 1.09 +/- 0.01) while its Km value was identical to that of the unlabeled substrate. The following substrate analogues were synthesized and assayed with PAL: cyclooctatetraenyl (COT)-d,l)-alanine as well as 2-pyridyl-, 3-pyridyl-, and 4-pyridyl-(l)-alanines. While COT-(d,l)-alanine turned out to be a rather reluctant substrate, all three isomers of pyridyl-(l)-alanines were converted with a comparable or even higher Vmax than l-phenylalanine into the corresponding pyridyl acrylic acids. Their Km values were, however, an order of magnitude higher than that of the natural substrate. These results are discussed in terms of the novel mechanism which implies an electrophilic attack of the prosthetic dehydroalanine at the aromatic ring. The heats of formation of the putative sigma complexes of the electrophilic substitution at the pyridine ring have been calculated using semiempirical force-field methods. The results show the feasibility of the proposed mechanism also with the substrate analogues.

Alanine↗
PubMed1998

Plasma active renin, angiotensin I, and angiotensin II during pregnancy and in preeclampsia.

OBJECTIVE: To evaluate the activity of the renin-angiotensin-aldosterone system in the circulation during the three trimesters of normal pregnancy and in women with preeclampsia. METHODS: Normal pregnant volunteers (n = 7) were studied throughout pregnancy, and women with preeclampsia (n = 8) were studied in the third trimester. Plasma active renin and aldosterone were measured by radioimmunoassay. Angiotensin I and angiotensin II were determined by radioimmunoassay after separation of the peptides by high-performance liquid chromatography. RESULTS: Active renin concentration increased in the first trimester of normal pregnancy, whereas angiotensin I, angiotensin II, and aldosterone remained at a level comparable to the postpartum values. Highest activity of the renin-angiotensin-aldosterone system was observed during the third trimester with increased levels of angiotensin I, angiotensin II, and aldosterone. In contrast, in patients with preeclampsia, despite a slight increase of active renin levels, the other parameters of the renin-angiotensin-aldosterone system were low compared with the third trimester of normal pregnancy and were comparable to postpartum data. CONCLUSION: Our results suggest that during the first trimester of normal pregnancy, active renin concentration in the plasma is increased and that renin is not the factor that limits angiotensin II synthesis. These results also confirm decreased activity of the renin-angiotensin-aldosterone system in preeclampsia. This could contribute to the diminished hemodynamic control observed in pregnant women developing preeclampsia.

Adult↗
PubMed1998

Etiology and prevention of pulmonary complications following beta-mimetic mediated tocolysis.

OBJECTIVES: This study documents biological (haematocrit variations) and therapeutic parameters (salbutamol doses, volumes perfused) in two groups tocolysed with salbutamol, one with and the other without APO in order to define the risk factors linked to APO and to establish a standard protocol of management. STUDY DESIGN: This retrospective study includes data from 68 intravenous salbutamol tocolysis with four resulting APOs, carried out between January 1st, 1993 and December 31st, 1995. RESULTS: There was an excessive level of salbutamol administered over 48 h in the complicated APO-group (122.5+/-52 mg) opposed to the non-APO group (44.9 21 mg) as well as an overload of perfused solute (3.1+/-1.11) versus (1.9+/-1.11). Blood hemodilution was demonstrated in the APO group with a decrease of haematocrit by over 10% between the admission and the control value. No other risk factor was found. CONCLUSION: Tocolysis should be administered at the lowest possible perfusion rate with incremental doses as long as the heart rate stays under 120 beats/min and stopped after 48 h. Administration of maximal 11 of solute perfused/day is recommended. For the patient's follow-up we estimate daily input and output fluid to avoid hydric overload, and a daily control of haematocrit whose variation must be less than 10%.

Acute Disease↗
PubMed1998

[Management of Rhesus isoimmunization. Viewpoint of the obstetrician].

Although rare, severe forms of Rhesus isoimmunization are still observed. Early diagnosis and treatment with intrauterine transfusions allow an 80% survival rate. Anti-D alloimmunizations usually result from missed prophylaxis with anti-D serum at delivery, thus underlying the need for a rigorous application of this prophylaxis.

Blood Transfusion, Intrauterine↗
PubMed1998

Low-field dedicated magnetic resonance imaging: a potential tool for assisting perinatal autopsy.

Although the practice of perinatal autopsy has increased in recent years, examination of the fetus and especially of the fetal brain during the first trimester or the beginning of the second trimester remains difficult. Postmortem high-resolution images of the brain of a normal and an abnormal fetus of the same gestational age (22 weeks) were obtained with a low-field (0.1 T) dedicated magnetic resonance imaging (MRI) system. We demonstrated that a small MRI machine supplemented data from classical necropsy and may help in the interpretation of in utero ultrasound and magnetic resonance images for the antenatal diagnosis of fetal malformations.

Adult↗
PubMed1998

Breech presentation after 34 weeks-a meta-analysis of corrected perinatal mortality/morbidity according to the method of delivery.

We conducted a meta-analysis of the mortality and morbidity of the breech presentation according to the method of delivery. Using the term 'breech', we used the Medline data base to search the English and French-language literature from 1978 to July 1995. Twenty-two studies (7239 deliveries) were found and analysed. The meta-analysis concerning perinatal mortality did not reveal a significant increased risk, when vaginal deliveries were compared with those delivered by a caesarean section (odds ratio: 1.90; confidence interval: 0.59-8.22) or when vaginal deliveries were compared with those done by planned caesarean section (odds ratio: 4.95; confidence interval: 0.44-80.06). The neonatal morbidity showed an increased risk with vaginal delivery. It is concluded that the practice of resorting to caesarean section for every breech presentation at term does not seem defensible.

Journal Article↗