Helium Double Photoi

The present status of double photoionisation studies is comprehensively reviewed. Recent findings are described which shed some light on the transition from the correlated motion of the two electrons near threshold to the shakeoff-like behaviour at higher photon energies. For extremely high photon energies, where Compton scattering becomes the dominant process, new results for the He2+ /He+ ratio between 6 and 120 keV are presented. The results confirm the prediction of Bergstrom et al. that the ratio reaches an intermediate maximum between 12 and 15 keV, before declining towards the asymptotic limit. Furthermore, this asymptotic limit seems not to be reached even at energies as high as 120 keV.

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.

[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.

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.

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%.

Sporadic case of dyssegmental dysplasia with antenatal presentation

Dyssegmental dysplasia is a rare micromelic dwarfism with characteristic clinical and radiological features. In skeletal dysplasias with severe micromelia prenatal detection of affected fetuses is possible using ultrasonography. However, prenatal diagnosis is usually performed after the occurrence of a previous case in the family. In this case dyssegmental dysplasia was detected prenatally in the first child of unaffected related (first cousins) parents. Fetal ultrasonographic examination in the 33rd week of gestation revealed a normal biparietal diameter of 94 mm and pronounced shortening of the extremities with femurs of 19 mm. The femurs were bowed. The spine showed severe malsegmentation. At radiological examination the long bones showed a dumbbell configuration especially in the longer extremities. The spine showed severe malsegmentations including coronal and sagittal clefting and multiple outsize vertebrae. The pelvis had very narrow sacrosciatic notches and rounded iliac wings. This case supports the autosomal recessive inheritance and demonstrates the possibility of prenatal diagnosis in non familial cases in this type of micromelic dwarfism.

[Role of the process of endothelium formation on the wall of the aortic prosthesis in protection against infection. Experimental study in dogs]

An experimental canine model was developed in order to evaluate the role of endothelialization of aortic prostheses for protection against septicemic infection and the utilization of 131I radiolabeled bacteria for vascular experimentation. Two groups of dogs were submitted to insertion of a dacron prosthesis segment in the abdominal aorta with subsequent infusion of inert 131I radiolabeled bacteria. In the first group ("A"), formed by five dogs, the infusion was made 30 minutes after the insertion of the prosthesis and in the second group ("B"), formed by four dogs, in a new surgery performed 12 weeks after. Fragments of the animals' prostheses and aortas were collected after 30 minutes of septicemia and analyzed by scan electron microscopy and submitted to reading of radioactivity uptake by a well-type counter. The microscopy recognized a complete endothelialization of the prostheses of dogs of group "B" 12 weeks after their insertion. Statistical analysis comparing fragments of non-endothelialized prostheses, of endothelialized prostheses and aortas demonstrated that the lower radioactivity uptake of the endothelialized prostheses in relation to non-endothelialized ones was significant (p = 0.0143) and that there was no significant statistical difference in uptake in the aortas and in endothelialized prosthesis (p = 0.3173). It was, therefore, concluded that prosthesis endothelialization fully protected them against septicemic infection; bacteremia contaminated all the non-endothelialized prostheses; there was no bacterial adhesion in the endothelialized prostheses and the use of bacteria labeled with radioisotope 131I is appropriate for the study of infections in vascular prosthetic devices.

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.

Surgical management of hepatocellular carcinoma: resection or transplantation?

Liver resection or transplantation offers the best opportunity for cure of hepatocellular carcinoma (HCC). To determine the relative roles for resection and transplantation and to evaluate the patient and tumor characteristics that might predict survival, the records of 125 patients treated for nonfibrolamellar HCC at The Toronto Hospital between 1981 and 1996 were reviewed. No adjuvant chemotherapy or antiviral protocols were used. Resection was the first operation in 67 patients; one underwent re-resection. Sixty patients underwent transplantation including two who had previously had a resection; 40 had known or suspected HCC and 20 had incidental tumors identified in the explanted liver. The incidence of cirrhosis was 49% for resection and 88% for transplantation. The incidence of hepatitis B virus (HBV) was 58% and 33%, respectively. The operative mortality rate for resection was 4.4% (9.4% in cirrhotic and 0 in noncirrhotic patients) and 13.3% for transplantation. The 5-year cumulative recurrence rate was 55% following resection and 20% following transplantation (P <0.001). The 5-year Kaplan-Meier survival rates were 38% for resection and 45% for transplantation-60% for transplanted HBV-negative and 17% for HBV-positive patients (P <0.001). After resection, recurrent HCC accounted for 86% of deaths, whereas recurrent HBV was responsible for 42% of deaths after transplantation. By univariate analysis, following resection, vascular invasion, advanced stage, multiple tumors, and lack of a capsule were predictive of survival; cirrhosis, HBV, age, tumor size, number, and grade were not. By multivariate analysis, only vascular invasion was predictive for resection and HBV for transplantation. Resection and transplantation are complementary methods of treating HCC. With the current organ shortage, resection should be considered first-line treatment. HBV-positive patients with HCC should only undergo transplantation in combination with effective antiviral therapy.

[What does the cesarean rate mean in France/]

For more than twenty-five years, the cesarean rate in France, as in other developed countries, has continued to increase, and in 1995 was 15.9%. Cesareans are now taken for granted by the general public, who are usually unaware of their consequences for maternal mortality and morbidity and continue to consider this form of delivery as the safest for the new born child. Yet it has been clearly demonstrated that cesarean deliveries are associated with higher rates of maternal and perinatal morbidity than vaginal deliveries and that they increase maternal mortality by a factor of from 5 to 7. From an economic standpoint, cesareans are between two and three times more expensive than vaginal deliveries. The two main indicators which account for the increase in cesareans are cicatricial uterus and dystocia. These are indicators in which individual practitioners' normal practice and the fear of medical malpractice suits play a clear role. There appears to be a particular correlation between the proportion of cesareans and obstetricians' insurance premiums, obstetricians' own assessment of the risk of malpractice suits and the number of complaints lodged against hospitals or individual doctors. Cesareans performed on grounds of fetal suffering or breech deliveries represent a diminishing proportion of the total. The use of scalp pH and radiopelvimetry have made it possible to restrict the number of cesareans based on these indicators. Other factors play a role in this increase, such as parity, education level, type of maternity insurance, whether the hospital is private or public, whether or not there is a neonatal resuscitation unit, the size of the city and the obstetrician's experience and type of training. The time and day or delivery have also been shown to be relevant factors. For obstetricians themselves, the higher fees earned from cesareans do not appear to be important. Of more relevance is the opportunity they offer doctors to organise their schedule and save time. Among the various methods proposed for reducing the cesarean rate, a strict definition of and respect for the indications for a cesarean, involving comparisons between establishments and between practitioners, have been shown to be effective. To allow such figures to be compiled, France should therefore produce for each confinement a standard record containing the different perinatal data, as is already the case in numerous other countries.

Multicenter study on the clinical value of fetal pulse oximetry. I. Methodologic evaluation. The French Study Group on Fetal Pulse Oximetry

OBJECTIVE

Our purpose was to evaluate the feasibility of intrapartum fetal pulse oximetry, the distribution of fetal oxygen saturation values, and the relationship with the neonatal outcome in a population with an abnormal fetal heart rate.

STUDY DESIGN

A prospective multicenter observational study was performed from June 1994 to November 1995. Fetal oxygen saturation was continuously recorded with use of a Nellcor N-400 fetal pulse oximeter in case of an abnormal fetal heart rate during labor. Simultaneous readings of fetal oxygen saturation and fetal blood analysis were obtained at inclusion and before birth. Feasibility, adverse effects, distribution of fetal oxygen saturation values, and relationship with neonatal outcome were assessed.

RESULTS

One hundred seventy-four 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 an attempt at fetal blood analysis (easy in 87.5% vs 78.9% for fetal blood analysis, 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 to 90th percentile range 30% to 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 low fetal oxygen saturation (< 30%) and 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.

Identification of essential amino acids in phenylalanine ammonia-lyase by site-directed mutagenesis

The postulated precursor of the prosthetic dehydroalanine of phenylalanine ammonia-lyase (PAL), serine 202, was changed to cysteine by site-directed mutagenesis. After cloning and heterologous expression in Escherichia coli, the gene product was assayed for PAL activity. Mutant S202C showed full catalytic activity, and its kinetic constants and the amount of thiol groups were identical to those of wild-type PAL. It must be concluded that in a posttranslational modification both water and hydrogen sulfide can be eliminated from the amino acid in position 202 to form dehydroalanine. In an attempt to identify further amino acids essential either for the posttranslational modification or for catalysis, arginine 174, glutamine 425, and lysine 499 were changed to isoleucine. Analysis of the heterologously expressed mutated gene products revealed that only the R174I mutant showed a significantly lower Vmax value (1/450) identifying this arginine as important. This finding was supported by treatment of wild-type PAL and mutant R174I with phenylglyoxal and 2,3-butandione. Both react specifically with the guanidino group of arginine. They irreversibly inhibited wild-type PAL but had no influence of the Vmax value of mutant R174I. Preincubation with l-phenylalanine protected wild-type PAL from inhibition by phenylglyoxal indicating that arginine 174 is close to the active site. Incubation with KCN irreversibly abolished the remaining activity of mutant R174I leading to the conclusion that arginine 174 is important in catalysis.

Multicenter study on the clinical value of fetal pulse oximetry. II. Compared predictive values of pulse oximetry and fetal blood analysis. The French Study Group on Fetal Pulse Oximetry

OBJECTIVE

Our purpose was to compare the predictive value of intrapartum fetal pulse oximetry with that of fetal blood analysis for an abnormal neonatal outcome in case of an abnormal fetal heart rate.

STUDY DESIGN

A prospective multicenter observational study was conducted from June 1994 to November 1995. Fetal oxygen saturation was continuously recorded with a Nellcor N-400 fetal pulse oximeter in case of an abnormal fetal heart rate 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-minute 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 10th percentile 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-operator characteristic curve showed similar performance of either technique for cutoff 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.

Antenatal diagnosis of brain damage in the survivor after the second trimester death of a monochorionic monoamniotic co-twin: case report and literature review

At 28 weeks of amenorrhea, 1 fetus of a monoamniotic twin pregnancy died. Ultrasound and Doppler investigations of the surviving twin were normal. Three weeks later, endovaginal ultrasound and magnetic resonance imaging revealed massive bilateral cerebral ischemic necrosis in the surviving twin. In utero fetal blood sampling carried out before the termination did not reveal either anemia or thrombopenia. Current data suggest that cerebral or renal ischemic complications could set in immediately after the death of the first twin as a result of a period of acute hypotension. At least 2 weeks are necessary for them to be identifiable by ultrasound. It seems that they cannot be prevented by prompt delivery of the second twin.

[Organically-induced delusional syndrome in psittacosis]

We report on a case of psittacosis which presented first as an atypical pneumonia and in the further course as a paranoid syndrome with a concomitant disorder of consciousness. In contrast with reports from the literature there were no obvious neurologic signs and symptoms which would have indicated the organic nature of the illness. Therefore, the correct diagnosis was based on a careful anamnesis, clinical and psychopathological examination and confirmatory results of serological tests.

Aggressive surgical management of fibrolamellar hepatocellular carcinoma

Fibrolamellar hepatocellular carcinoma (FLHC) is recognized as a distinct clinicopathologic variant of hepatocellular carcinoma. Ten consecutive patients with FLHC undergoing operative management at our institution were reviewed. At the initial presentation seven patients had stage II disease (pT2N0M0), whereas three patients were in stage III (pT2N0M0 or pT3N0M0). Initial procedures included formal right or left hepatectomy in four patients, right or left trisegmentectomy in two patients, left lateral segmentectomy or nonanatomic resection in three patients, and in one patient considered for liver transplantation, only exploration with biopsy of positive nodes was performed. Four stage II patients required a second procedure for resection of recurrent disease from 8 months to 6 years after the initial resection and one patient required a third procedure after 13 years. Reoperations included hepatic re-resection, resection of extrahepatic disease, and liver transplantation. Overall 5- and 10-year Kaplan-Meier survival was 70%. There were no deaths among stage II patients (follow-up 96 to 180 months). All stage III patients (i.e., lymph node involvement, vascular invasion, or multiple tumors) died within 5 years. Patients with stage II disease had better survival than patients with stage III disease (P = 0.011, log-rank test). Aggressive treatment of FLHC including reoperation and liver transplantation is justified, especially in patients with stage II disease.

A study of prognostic factors for hepatic resection for colorectal metastases

BACKGROUND

Liver resection is accepted treatment for selected patients with colon cancer metastatic to the liver. There remains some controversy regarding the selection criteria, particularly which preoperative features are useful predictors of long survival postresection.

METHODS

One hundred and twenty-three patients who had liver resection for colorectal metastases on the Hepato Pancreatic Biliary Service at The Toronto Hospital between August 1977 and June 1993 were studied. Seventy-seven had solitary lesions, 15 had single lesions with satellite nodules, and 31 had multiple lesions. Synchronous liver metastases were found in 40 patients and 83 patients had metachronous lesions. Fifty-one patients had formal lobectomies and 21 had extended lobectomies.

RESULTS

Postoperative complications were seen in 28% of patients, but there were no operative or postoperative deaths. Overall actuarial 5-year survival was 34%. There was a significant difference in survival according to the number of metastases. Patients with single lesions had a 5-year survival of 47% compared with 16% for single lesions with satellite nodules, and 17% for multiple lesions. There were no significant differences in survival based on age, sex, synchronous versus metachronous lesions, status of lymph nodes at the time of original surgery, intraoperative blood replacement, or size of tumor.

CONCLUSIONS

An aggressive approach to the surgical management of colorectal liver metastases is possible with low risk in centers specializing in liver surgery, and results in prolonged survival in one third of patients. The most reliable predictor of long-term survival is the number of metastases in the liver.

Fetal pulse oximetry and fetal heart rate monitoring during stage II of labour

OBJECTIVE

This study was designed to assess the changes in fetal oxygen saturation (FSpO2) using fetal pulse oximetry when the fetal heart rate (FHR) monitoring became abnormal during stage II of labour.

STUDY DESIGN

FSpO2 was recorded with the Nellcor N400 Oximeter (FS-14 sensor) and was averaged over the last 10 min of the second stage of labour. Second stage FHR patterns were assessed according to Melchior's classification.

RESULTS

In terms of FHR patterns, FSpO2-10" measured 41.4% in type 0 (n = 5), 42.4% in type 1 (n = 19), 43.3% in type 2 (n = 6), 34.0% in type 3 (n = 4) and 27.6% in type 4 (n = 7) (P = 0.03).

CONCLUSIONS

FSpO2-10" decreases in cases of severe FHR abnormality during the second stage of labour and could help to decide whether to perform an instrumental extraction.