Hematopoietic stem cell gene therapy of murine protoporphyria by methylguanine-DNA-methyltransferase-mediated in vivo drug selection

Erythropoietic protoporphyria (EPP) is an inherited defect of the ferrochelatase (FECH) gene characterized by the accumulation of toxic protoporphyrin in the liver and bone marrow resulting in severe skin photosensitivity. We previously described successful gene therapy of an animal model of the disease with erythroid-specific lentiviral vectors in the absence of preselection of corrected cells. However, the high-level of gene transfer obtained in mice is not translatable to large animal models and humans if there is no selective advantage for genetically modified hematopoietic stem cells (HSCs) in vivo. We used bicistronic SIN-lentiviral vectors coexpressing EGFP or FECH and the G156A-mutated O6-methylguanine-DNA-methyltransferase (MGMT) gene, which allowed efficient in vivo selection of transduced HSCs after O6-benzylguanine and BCNU treatment. We demonstrate for the first time that the correction and in vivo expansion of deficient transduced HSC population can be obtained by this dual gene therapy, resulting in a progressive increase of normal RBCs in EPP mice and a complete correction of skin photosensitivity. Finally, we developed a novel bipromoter SIN-lentiviral vector with a constitutive expression of MGMT gene to allow the selection of HSCs and with an erythroid-specific expression of the FECH therapeutic gene.

[In utero exposure to benzodiazepine. Is there a risk for anal atresia with lorazepam?]

Drugs of the Benzodiazepine family are among the most frequently prescribed in France. Since anxiety disorders, for which these substances are mostly indicated, affect 10% of pregnant women, it is very likely that such a treatment could expose many foetuses to BZD during the first three Months of pregnancy. We know that the teratologic effect is not necessarily based on dose rate, but that it is associated with fetal drug exposure during the first 12 weeks of gestation, when organ formation occurs. Most epidemiologists concur that the baseline incidence of congenital damage is 2-2,5% in Europe. The results from a large number of stu-dies on associations between the use of BZDs in pregnancy and congenital malformations are conflicting. An in-depth analysis of existing literature shows results that are hardly comparable, if not contradictory, due to extreme differences in methodological approaches. In a recent meta-analysis case-control studies and cohort studies were analyzed separately. Among the case-control studies significant associations were found between BZD exposure and both, major malformations and oral clefts, whereas the cohort studies showed no association between BZD and any kind of malformation. The purpose of our study is to search for a specific teratogenic effect of this class of drugs, using data collected (1976-1997) by the French Central-East (FCE) registry of congenital malformations, member of the International Clearinghouse for Birth Defects Monitoring Systems (ICBDMS) located in Lyon, France. This registry monitor malformations among 100,000 births per Year. We analyzed 13,703 cases where information is available on whether or not the mother took a drug during her first trimester of pregnancy. Among them, 3,603 (28%) actually took a drug, and 262 (6.8%) took some sort of benzodiazepine (BDZ). BZD were divided into 9 categories, 8 being the most frequently present, plus one broad category of "others". Malformations were divided into ten categories: congenital anomalies of heart, cleft lip and/or cleft palate, neural tube defects, other anomalies of central nervous system, hypospadias, urinary malformations, anal atresia, other digestive anomalies, limb reduction defects, and genetic anomalies, including chromosome aberrations and monogenic conditions. Other malformations were grouped in an eleventh category. The interesting aspect of this study is that it takes into account the BZD metabolism. It is worth noting that the hepatic catabolism of benzodiazepine is a very complex one, because it leads to derived molecules which are sometimes active and/or present in the common metabolic route of major commercial drugs. Our hypothesis is that if one BZD is associated specifically to a certain type of congenital defect, we may find this BZD to be overrepresented, as compared with other BZDs, in newborns exhibiting some type of congenital defect. The analysis was run according to a case-control approach. Odd ratios (OR) and their 95% confidence intervals were calculated by logistic regression with adjustment for maternal age and parity. When one category of defects was considered, infants having the corresponding malformation were considered as cases, while infants with other malformations were considered as controls. In a similar way infants having being exposed to a given drug were considered as exposed, while infants exposed to any other drug were considered as unexposed. The analysis then was run in 4 steps. Step 1: full sample. With 13,703 cases. We observed no increased risk for any specific malformation type associated with use of BZD. Step 2: further defining drug exposure as a specific BZD, and all others unexposed, a significant association was seen between lorazepam and anal atresia. OR=6.2 (95% CI2.4-15.7, p=0.01). Step 3: this finding was upheld and no other emerged when exposure was defined as the drug or any of its active metabolites. This step was performed because hepatic catabolism of BDZs leads to derived molecules that are sometimes active and/or present in the common metabolic route of major marketed BZDs. Step 4: similarly, the lorazepam/anal atresia finding was upheld when the analysis was restricted to the 262 malformed infants exposed to BZDs in utero. Six cases of anal atresia were found among all newborns exposed to BZD in utero, and five of them were exposed to lorazepam, representing a hypothesis to be tested in further. We are not aware of other reports of this association, and it should be regarded as preliminary until confirmed in other data sets.

Does high-sucrose diet alter skeletal muscle and liver mitochondrial respiration?

A diet high in sucrose or fructose progressively impairs glucose and lipid metabolism, which leads to insulin resistance. As mitochondria are the sites of the oxidation and utilization of these substrates, we hypothesized that a high sucrose diet would alter mitochondrial respiration. Male Wistar rats were fed high-sucrose (SU) or control (CTL) diet for one week; mitochondrial respiration was investigated in mitochondria isolated from liver and both glycolytic and oxidative muscles, with pyruvate and palmitate as substrates. To test for metabolic disturbances, we measured not only glycogen content in muscles and liver, but also lactate, glucose and triglyceride blood concentrations. After one week of high-sucrose intake, we found no change in blood concentration of these variables, but glycogen content was significantly increased in liver (17.28 +/- 2.98 mg/g tissue SU vs 6.47 +/- 1.67 mg/g tissue CTL), oxidative muscle (1.59 +/- 0.21 mg/g tissue SU vs 0.70 +/- 0.24 mg/g tissue CTL) though not in glycolytic muscle (1.72 +/- 0.44 mg/g tissue SU vs 1.52 +/- 0.20 mg/g tissue CTL). State 3 mitochondrial respiration was significantly decreased in SU rats compared with CTL (p < 0.05) with pyruvate, while no change was observed with palmitate. This study shows that 1-week of high-sucrose diet altered mitochondrial pyruvate oxidation in rats and suggests that, in the context of a high-sucrose diet, impaired mitochondrial respiration could contributed to the development of insulin resistance.

The epidemiology of cardiovascular defects, part 2: a study based on data from three large registries of congenital malformations

There were three objectives of this study: to investigate possible specificity in the association between specific cardiac defects and chromosomal anomalies; to evaluate ways of categorizing cardiac defects into larger groups with epidemiological similarities that could indicate similarities in etiology or pathogenesis; and to analyze the relationship between specific cardiac defects and diabetes. We pooled data on infants (aged 1 year or younger) with congenital cardiovascular defects from three large birth defect registries in California, Sweden, and France. The registries in Sweden and France obtained data through reporting from various sources; in California, medical records were reviewed. For severe congenital heart defects, the percentage of infants with identified chromosomal anomalies varied between 0.9% for d-TGV to 68.4% for ECD. In general, specific cardiac conditions have different risk factors. For example, conotruncal defects have been traditionally grouped, but the data presented in this paper indicates more differences for risk factors for the components of conotruncal defects: tetralogy of Fallot, d-TGV, common truncus, and DORV. In general, we suggest the strategy of "splitting" rather than "lumping" when searching for specific genetic factors and/or teratogens. Adequate analysis thus requires large registries or collaboration among registries. The findings did not support constellations between mothers' diabetes and specific defects.

The epidemiology of cardiovascular defects, part I: a study based on data from three large registries of congenital malformations

To analyze complex and noncomplex cardiac malformations regarding prevalence and in relation to demographic variables, we pooled data on infants (age 1 year or younger) with congenital cardiovascular defects from three large birth defect registries in California, Sweden, and France. Altogether, 12,932 infants had one or more congenital heart defects out of 4.4 million live births and stillbirths. The registries in Sweden and France obtained data through reporting from various sources; in California, medical records were reviewed. As expected, definitions and ascertained conditions differed among each of the registries. The total rates for severe defects were similar (1.43 per 1,000), but differed for specific defects. Clear differences in epidemiological characteristics existed for specific defects; for example, severe cardiac defects sex ratios were significantly high for hypoplastic left heart syndrome, d-transposition of great vessels, double outlet right ventricle, total anoralous pulmonary venous return, tetralogy of Fallot, and significantly low for pulmonary atresia without ventricular septal defect and endocardial cushion defect. Few defects were similar for several epidemiological characteristics, but, for example, the combination of ventricular and atrial septal defects appeared equivalent with endocardial cushion defect under some circumstances, yet behaved differently with regard to associated noncardiovascular defects.

[Down syndrome and ionizing radiation: causal effect or coincidence]

Annual and monthly prevalence of Down's Syndrome has been analyzed in Belarus for a 19-year period (1981 to 1999). The distribution of 2786 DS cases during this period showed no significant long-term prevalence trend. Meanwhile, 2 marked increases of DS prevalence were registered in 1987 and 1990. The most remarkable annual increases were observed in 1987 in Minsk city, in Vitebsk oblast (considered as contamination-free administrative district) and in Minsk oblast (partially contaminated area), data not shown in the text. Much more marked and significant increases were recorded in January 1987, in Minsk city, Gomel oblast and Minsk oblast. However it is impossible to establish a causal relationship between these clusters of DS and exposure to the Chernobyl fallout, at a geographical level. The presence of such a cluster 9 months after the explosion in one of the most exposed area (Gomel oblast) should incite to careful conclusions and prompt further studies.

Chromosomal congenital anomalies and residence near hazardous waste landfill sites

Previous findings of the EUROHAZCON study showed a 33% increase in risk of non-chromosomal anomalies near hazardous waste landfill sites. Here, we studied 245 cases of chromosomal anomalies and 2412 controls who lived near 23 such sites in Europe. After adjustment for confounding by maternal age and socioeconomic status, we noted a higher risk of chromosomal anomalies in people who lived close to sites (0-3 km) than in those who lived further away (3-7 km; odds ratio 1.41, 95% CI 1.00-1.99). Our results suggest an increase in risk of chromosomal anomalies similar to that found for non-chromosomal anomalies.

Adverse effects of prenatal methimazole exposure

BACKGROUND

A specific phenotype of methimazole (MMI) induced malformations has recently been postulated. MMI embryopathy is characterized by minor dysmorphic features, choanal atresia and/or esophageal atresia, growth retardation, and developmental delay.

METHODS

We prospectively studied the outcome of pregnancy in 241 women counseled by 10 Teratology Information Services (TIS) of the European Network of Teratology Information Services (ENTIS) because of MMI exposure, and compared them with those of 1,089 pregnant women referred to TIS because of exposure to nonteratogenic drugs (control group). Information was obtained by mail or telephone interview.

RESULTS

There was no increase in the general rate of major anomalies or of spontaneous or induced abortions in the MMI-exposed group in comparison with the control group. Two newborns were affected with one of the major malformations that are part of the postulated embryopathy.

CONCLUSIONS

The results of this study indicate that choanal as well as esophageal atresia may have a higher incidence than expected in fetuses exposed to MMI between 3 and 7 gestational weeks. Until further data are available, thyrotoxicosis should be treated with propylthiouracil, as it is apparently safer for use during the fertile period.

Epidemiologic characteristics of kidney malformations

Infants with kidney agenesis or dysgenesis, infants with cystic kidneys, and infants with horseshoe kidneys were studied, based on data from three large and population-based congenital malformation registers: a total of 2666 infants among 5.83 million births. There is a strong variability between programs of the rates of registered unilateral kidney malformations and these are strongly over-represented in dead infants or infants with other malformations. There is a male excess but this varies in strength between different types of kidney malformations and between bilateral and unilateral forms. An increased twinning rate was found. The different types of kidney malformation differed with respect to kind of associated non-urological malformations in multimalformed infants. We conclude that for monitoring purposes one should restrict analysis to bilateral forms but that unilateral forms can be of interest in epidemiological analyses.

VATER non-random association of congenital malformations: study based on data from four malformation registers

This study was undertaken to find a strict, unbiased epidemiological delineation of the VATER non-random association of congenital malformations and, based on registry information, to identify a group of probable VATER association infants suitable for etiological analyses. Information on 5,260 infants with multiple malformations was collected from four large registers of congenital malformations. Data were analyzed using a statistical method in which various putative confounders were controlled for. Our results indicate the existence of a distinct group of malformations corresponding to the VATER association: esophageal atresia, anal atresia, upper preaxial limb reduction defects, and costo-vertebral malformations. A subdivision into an upper and a lower group of VATER association was indicated, with heart malformations associated with the upper group and kidney malformations associated with the lower group. Restricting the inclusion criteria for VATER association to the above mentioned core malformations, few infants seem to belong to the VATER association, thus limiting the possibilities of carrying out etiological analyses. A relatively large number of infants may belong to a family of related conditions among which VATER association is a subgroup. In the search for risk factors, a strict definition of the VATER association is needed in order to not dilute the study material with irrelevant cases. The present study provides such strict inclusion criteria.

Teratogenic effects of antiepileptic drugs: use of an International Database on Malformations and Drug Exposure (MADRE)

PURPOSE

The study goal was to assess teratogenic effects of antiepileptic drugs (AEDs) through the use of a surveillance system (MADRE) of infants with malformations.

METHODS

Information on all malformed infants (1990-1996) with maternal first-trimester drug exposure was collected by the International Clearinghouse for Birth Defects and Monitoring Systems (ICBDMS). Cases were defined as infants presenting with a specific malformation, and controls were defined as infants presenting with any other birth defect. Exposure was defined by the use of AEDs during the first trimester of pregnancy. The association of AEDs with malformations was then estimated by calculating the odds ratios with 95% confidence intervals and testing their homogeneity among registries.

RESULTS

Among 8005 cases of malformations, 299 infants were exposed in utero to AEDs. Of those exposed to monotherapy, 65 were exposed to phenobarbital, 10 to methylphenobarbital, 80 to valproic acid, 46 to carbamazepine, 24 to phenytoin, and 16 to other AEDs. Associations were found for spina bifida with valproic acid. Infants exposed to phenobarbital and to methylphenobarbital showed an increased risk of oral clefts. Cardiac malformations were found to be associated with phenobarbital, methylphenobarbital, valproic acid, and carbamazepine. Hypospadias was associated with valproic acid. Porencephaly and other specified anomalies of brain, anomalies of face, coarctation of aorta, and limb reduction defects were found to be associated with valproic acid.

CONCLUSIONS

Using the MADRE system, we confirmed known teratogenic effects of AEDs. We also found increased risks for malformations that had never been reported associated with AEDs or for which the association was suggested by case reports.

[Occupational exposure to organic solvents and pregnancy. Review of current epidemiologic knowledge]

The findings and methodological issues of recent epidemiological studies (1989-1999) on adverse developmental effects of maternal occupational exposure to organic solvents are reviewed. Several studies suggest the possibility of a moderate increase in the risk of spontaneous abortion and congenital malformations, especially facial clefts, associated with maternal exposure to solvents. A common methodological weakness of these studies is the inaccuracy of data on exposures. Positive findings encourage further epidemiological studies of high-quality design and use of protective measures to minimize exposure to these agents from the preconceptional period to the end of pregnancy.

Comparison of the diagnostic value of cardiac troponin I and T determinations for detecting early myocardial damage and the relationship with histological findings after isoprenaline-induced cardiac injury in rats

Cardiac troponins I (cTnI) and T (cTnT) have been shown to be highly sensitive and specific markers of myocardial cell injury. The purpose of this study was to investigate the diagnostic value of cTnI and cTnT with regard to creatine kinase (CK) and lactate dehydrogenase (LD) and to determine whether they can be used for early diagnosis of myocardial damage in rats, and to examine the relationship between cTnl and cTnT release with histological examinations, using isoprenaline-induced cardiac muscle damage as an experimental model in the rat. Eighteen Wistar rats per group were treated with a single dose of either isoprenaline (iso) or with normal saline as a control group. The anti-cTnI and cTnT monoclonal antibodies (mAbs) employed in the cTnI (Access) and cTnT (Elecsys) assays cross-react with cTnI and cTnT of the rat. A highly significant rise of cTnl or cTnT was found already 2 h after iso. The time-courses of cTnI and cTnT were monophasic in form. The highest cTnI (mean+/-S.D., 1.1+/-2.3 ng/ml) and cTnT (mean+/-S.D. 3.6+/-30 ng/ml) were found 4 h after iso. cTnI and cTnT significantly increased in iso-treated rats in comparison with controls whether the differences between 2-, 4- and 6-h levels and basal levels were considered or not. The areas under cTnl and cTnT curves (AUC) (0-6 h) and the maximal cTnI and cTnT (0-6 h) after iso were significantly different from the controls. For CK and LD, no elevation in comparison with controls could be detected (except a trend for LD whether or not the difference between 6-h levels and basal levels were considered (P=0.08) and for LD AUC (0-6 h) (P=0. 059)). Correlations between maximal cTnI and cTnT and AUC were 0.69 (P=0.0001) and 0.60 (P=0.0066), respectively. Histological examinations of iso-treated rats revealed acute focal or multifocal myofibrillar degeneration of the myocardial tissue in ten out of 14 rats and showed the earliest alterations 4 h after iso in one treated rat. Only four of the controls exhibited evidence of mild changes and slight mononuclear cell infiltration. cTnl and cTnT peak values to at least 0.35 and 1.3 ng/ml, respectively, were necessary to detect histological myocardial cell injury after iso. cTnI and cTnT were found to be early markers for diagnosing iso-induced myocardial damage in comparison with CK and LD. Elevations of cTnI and cTnT appeared to relate to the severity of histologic changes after myocardial injury. Although there was a difference in the absolute concentration of results between cTnI and cTnT assays, due to a lack of standardization and heterogeneity in the cross-reactivities of mAbs to various troponin I and T forms, cTnI and cTnT can be used as easily measurable target parameters for detection of cardiotoxic and/or cardiodegenerative effects in rats.

Drinking water chlorination and delivery outcome-a registry-based study in Sweden

By using the Swedish Medical Birth Registry and official data on drinking water chlorination, three cohorts were identified and compared: women who lived in areas where drinking water was disinfected with chlorine dioxide, women who lived in areas that used sodium hypochlorite disinfection, and women who lived in areas where there was no chlorination of the drinking water. There was a statistically significant increase in short gestational duration and low birth weight and especially in short body length and very small head circumference in areas using sodium hypochlorite, but no significant effects on these variables were found in areas using chlorine dioxide. No effects on congenital malformations, childhood cancer, infant mortality, low Apgar score, neonatal jaundice, or neonatal hypothyroidism were associated with either of the two drinking water chlorination methods. Because the exposure information in this study was based on the chlorination method and not the amount of byproducts in the water, the general lack of significant effects could be due to a low concentration of such byproducts.

OEIS complex--a population study

Using a novel method for the analysis of infants with multiple malformations, we investigated the cluster of associated malformations called the OEIS (omphalocele, bladder exstrophy, imperforate anus, spine defect) complex among 5,260 infants with multiple malformations identified in four large registers of congenital malformations, corresponding to 5.84 million births. The existence of the OEIS complex was clearly demonstrated and malformations entering it could be defined. Other than the four classical malformations, omphalocele, bladder exstrophy, imperforate anus, and spine malformation, a strong association with spina bifida and intersex was stressed. Spine malformations occurred not only in the lumbosacral level but also more cranially, and an association also with upper spina bifida could be demonstrated. No specific association with any other malformation, including cardiac defects, was apparent. The OEIS complex is an unusually clearly defined entity among the various nonrandom associations which have been described.

Mechanisms of ventricular arrhythmias induced by myocardial contusion: a high-resolution mapping study in left ventricular rabbit heart

BACKGROUND

The aims of the Langendorff-perfused rabbit heart study were to evaluate the arrhythmogenic consequences of myocardial contusion and to determine the mechanism of arrhythmia.

METHODS

Six hearts were in the control group, and 24 hearts (intact heart protocol) were submitted to one of four different contusion kinetic energies (75, 100, 150, or 200 millijoules [mJ]; n = 6). Occurrence of arrhythmia, of an electrically silent area (i.e., area with no electrical activity), and of line of fixed conduction block were reported before and for 1 h after contusion. In 16 hearts (frozen hearts) submitted to cryoprocedure and contusion impact of 100 or 200 mJ, ventricular conduction velocities, anisotropic ratio, wavelengths, ventricular effective refractory period, and its dispersion were measured before and for 1 h after contusion. Using high-resolution mapping, arrhythmias were recorded and analyzed.

RESULTS

The intact heart study showed that the number and seriousness of contusion-induced arrhythmias increased with increasing contusion kinetic energy, as did the number of electrically silent areas (five of six ventricular fibrillations and five of six electrically silent areas at 200 mJ). In the frozen heart study, immediately after contusion ventricular effective refractory periods were shortened and dispersed, and wavelengths were also shortened. The arrhythmia analysis showed that all ventricular tachycardias but one were based on reentry developed around an electrically silent area or a line of fixed conduction block.

CONCLUSIONS

Myocardial contusion has direct arrhythmogenic effects, and the seriousness of arrhythmia increases with the level of contusion kinetic energy. The mechanism of arrhythmia was mainly based on reentrant circuit around a fixed obstacle.

CHARGE Association in newborns: a registry-based study

The CHARGE Association is a nonrandom occurrence of congenital malformations that has been described in clinical series. Reported patients have been selected on the basis of certain prior criteria. In this article, we try to identify a congenital malformation pattern corresponding to the CHARGE Association, using statistical methods and analyzing 5,260 infants with multiple malformations collected from four large registries of congenital malformations. Care was taken to identify a number of confounding characteristics that can influence the ascertainment and registration of specific congenital malformations. We have identified a cluster of malformations that generally agreed with the current clinical definition of the CHARGE Association and have added some further malformations (e.g., facial clefts). We demonstrate that others (e.g. , esophageal atresia) are probably not part of the pattern. Heart defects (H in the acronym) seems to be less helpful in identifying infants with the association. We suggest a method to select infants who probably represent the CHARGE Association for analyses of possible risk factors.

Effects of halothane and enflurane on ventricular conduction, refractoriness, and wavelength: a concentration-response study in isolated hearts

BACKGROUND

Effects of halothane and enflurane on ventricular conduction, anisotropy, duration and dispersion of refractory periods, and wavelengths were studied, and putative antiarrhythmic or arrhythmogenic properties on ventricles were discussed.

METHODS

High-resolution epicardial mapping system was used to study the effects of 1, 3, and 5 vol% halothane and enflurane in 30 isolated rabbit hearts. Ten hearts were kept intact to study the effects on spontaneous sinus cycle length (RR interval), perfusion pressure, and the occurrence of spontaneous dysrhythmias. In 20 other hearts, a thin epicardial layer was obtained (frozen hearts) to study ventricular conduction velocity, ventricular effective refractory period (VERP in four sites) and wavelengths.

RESULTS

Halothane induced a concentration-dependent lengthening of RR interval, whereas enflurane did not. Both agents slowed longitudinal and transverse ventricular conduction velocity with no anisotropic change. Ventricular effective refractory period was prolonged at 1 vol% and was shortened at higher concentrations, with no significant increase in dispersion. Ventricular longitudinal and transverse wavelengths decreased in a concentration-dependent manner. Although changes in wavelengths could express proarrhythmic effects of volatile anesthetics, no arrhythmia occurred in spontaneously beating hearts or in frozen hearts.

CONCLUSIONS

The ventricular electrophysiologic effects of halothane and enflurane were slight, suggesting that both agents are unable per se to induce functional conduction block and therefore reentrant ventricular arrhythmias.

Time trends in neural tube defects prevalence in relation to preventive strategies: an international study

OBJECTIVE

To examine time trends in neural tube defects (NTD) prevalence from 1987 to 1996 in relation to the primary prevention policies for folic acid supplementation strategies in different countries.

DESIGN

Retrospective time trends analysis of NTD prevalence.

SETTING

11 birth defect registries of congenital malformations participating in the International Clearinghouse for Birth Defects Monitoring System, in the period from 1 July 1987 to 30 June 1996.

SUBJECTS

8207 live births, stillbirths and terminated pregnancies affected by anencephaly or spina bifida registered by the 11 participating centres 1987-1996.

OUTCOME MEASURES

Prevalence rate ratios based on the annual rates, using the Poisson regression model.

RESULTS

During the study period a significant fall in prevalence rates for all NTD is present in Atlanta (USA), England and Wales, Hungary and Japan, and a significant rise in Norway and South America. After adjusting for the secular trends observed in the earlier years of the study, no significant trend can be attributed to preventive strategies. Data on NTD prevalence are supplemented with information on folate awareness among some of the populations studied.

CONCLUSION

There is no evidence that, up to the middle of 1996, any change in time trend was attributable to the introduction of national folate supplementation policies. The possible effectiveness of folate supplementation policies for the reduction of NTD clearly needs to be tried and studied for several more years. Considering that in the Western world about 50% of pregnancies are unplanned, a policy that rests on action taken before conception can only have limited success. Strategies based on food enrichment, such as was introduced in the USA from the beginning of 1998, may prove to be more successful.

Release kinetics of cardiac troponin I and cardiac troponin T in effluents from isolated perfused rabbit hearts after graded experimental myocardial contusion

BACKGROUND

Few experimental studies report effects of direct contusion on cardiac enzyme release. Cardiac troponins I (cTnI) and T (cTnT) have been shown to be highly sensitive and specific markers of myocardial cell injury. This investigation was designed to determine and compare the acute effects of quantified magnitudes of blunt cardiac trauma upon release of cTnI and cTnT in comparison with creatine kinase (CK) and lactate dehydrogenase (LD).

METHODS

In 24 rabbit hearts prepared on a standard Langendorff apparatus, myocardial contusion (MC) was produced by a single blow with a ball falling from a predefined height, delivered directly to the surface of the heart. Hearts were divided into control (n = 6) and various quantified impacts: 75 mJoules (mJ) (n = 6), 100 mJ (n = 6), 200 mJ (n = 6). Coronary effluent samples for cTnI, cTnT, CK, and LD were collected at baseline, immediately after MC and 5, 15, 30, 45, and 60 minutes after MC. At the end of experiment, histologic condition was evaluated.

RESULTS

The anti-cTnI and cTnT MAbs used in the cTnI (Access) and cTnT (Elecsys) assays cross-react with cTnI and cTnT of the rabbit. The time-courses of cTnI, cTnT, CK, and LD were monophasic in form. After MC, all parameters rose significantly compared with baseline and with control group. The maximal release occurred immediately after MC. The area under the cTnI curve and the maximal cTnI concentration were linked to the contusion energy when increased at 200 mJ. Maximal concentrations and areas under cTnT, CK, LD time activity curve were not linked to the contusion energy level and showed no between-energy group differences. The correlation found between maximal cTnI and maximal cTnT concentrations was 0.70 (p = 0.0001). Histologic examination showed cellular disruption and after the more severe impact, the extent of pathologic changes was more extensive.

CONCLUSION

After graded experimental MC, maximal cTnI concentration and area under cTnI curve increase with the power of impact kinetic energy. Levels of cTnI allow a much higher accuracy in detecting the extent of myocardial injury postMC in comparison with cTnT, CK, and LD in this experimental study. These results should be consistent with the more extensive cTnI release with more severe impact in patients with blunt chest trauma. Furthermore, because specificity and time-course of release, both cTnI and cTnT should have a role in the diagnosis and evaluation of such patients.

A modified method for the epidemiological analysis of registry data on infants with multiple malformations

BACKGROUND

Infants with multiple malformations are important in birth defect epidemiology and malformation monitoring because human teratogens have often caused complex malformations. Various methods for the analysis of multimalformed infants have been tried.

METHOD

By using data from four large registries of congenital malformations, 5256 infants were identified with two or more among 73 selected malformations. Pairwise associations between malformations were detected by multiple logistic regression analyses, and putative confounders (programme, maternal age, autopsy, etc.) were controlled for. For each significant pairwise association, further analyses were performed in order to find associations with a possible third malformation.

RESULTS

The importance of controlling for several confounders was demonstrated. Several well-known associations were found, which supports the technique used. The interpretation of three-way associations was discussed. Results from the present study were compared with those obtained using some other methods.

CONCLUSIONS

Different confounders can cause biased associations. The method presented in the paper takes this into consideration and is therefore more likely than previously used techniques to give unbiased information on the clustering of different malformations among multimalformed infants.