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Biomedical subjects

D Tibboel

Publications and source records attributed to D Tibboel.

At least 19 recordsLinked to original sources
PubMed1995

Hepatic artery ligation for hepatic vascular tumors with arteriovenous and arterioportal venous shunts in the newborn: successful management of two cases and review of the literature.

The authors report their experience with hepatic artery ligation in two newborns, as well as relevant findings from a literature review. A 2-day-old boy had progressive cardiac and respiratory difficulty. A firm liver was palpable, with an overlying thrill. Sonography and arteriography showed diffuse arteriovenous shunting in both liver lobes. Hepatic artery ligation provided remarkable hemodynamic and clinical improvement. Another boy was admitted 3 weeks after birth because of bilious vomiting with abdominal distension and bloody stools. Abdominal examination showed a large liver with a systolic bruit and thrill. X-rays showed cardiac enlargement and dilated bowel loops with air-fluid levels. Arteriography and sonography showed arteriovenous and arterioportal venous shunting. Laparotomy was performed, and a large vascular malformation was palpated in both liver lobes. The entire bowel was congested and cyanotic, but there were no signs of obstruction. This patient had acute portal hypertension imitating intestinal obstruction. Ligation of the hepatic artery improved the color of the bowel, and the thrill disappeared. Five and nearly 4 years after the operation, both boys are growing normally without medication or diet. Sonography showed almost complete resolution of the hemangiomas.

Arteriovenous Malformations↗
PubMed1995

Amnio-allantoic fluid exchange for the prevention of intestinal damage in gastroschisis: an experimental study on chick embryos.

In gastroschisis, the protruding intestine is usually shortened, thickened, and covered with a fibrous peel. Urine components, which are increased in the amniotic fluid with the onset of renal function, are responsible for these changes. In the chick embryo model of gastroschisis, the authors performed amnio-allantoic fluid exchange to reduce the effect of urinary products. There were three study groups: control, gastroschisis only, and gastroschisis plus exchange. There was a significant decrease in creatinine (P < .05) and a slight decrease in urea concentrations in the gastroschisis-plus-exchange group compared with the gastroschisis-only group. Whereas macroscopic and microscopic studies showed severe fibrosis and bowel-wall thickening in the latter group, the bowel was normal or slightly oedematous in the former. On the basis of this study, the authors suggest that antenatal amniotic fluid exchange might reduce the bowel damage in human foetuses.

Abdominal Muscles↗
PubMed1995

Prospective evaluation of the absorptive capacity of the bowel after major and minor resections in the neonate.

The outcome after major bowel resection in the neonatal period depends primarily on the time needed for bowel adaptation. A prospective study was begun in neonates after small bowel resection to evaluate the absorptive capacity of the bowel and growth parameters as a result of adaptation of the bowel. Twenty-four neonates who underwent bowel resection were included. The underlying diagnoses were necrotising enterocolitis (12), jejunal atresia (3), meconium peritonitis (3), and other (6). During the study, a standardized treatment with respect to nutrition was followed. At predetermined times, enterostomy fluid or faeces were collected for analysis of carbohydrate content, fat content, and fatty acids, together with a xylose test and a hydrogen breath test. Growth parameters included weight and height. The 24 patients were divided into two groups. Group A consisted of eight patients with short bowel syndrome (defined as loss of more than 50% of the original small bowel length related to gestational age). The mean remaining small bowel length in this group was 34.0% (24% to 42%). Group B consisted of 16 patients who had only minor bowel resections. Retarded growth was observed in four group A patients. Low levels of carbohydrate absorption were found 2 and 4 weeks after the initial operation in group A, and 2 weeks after the initial operation in group B. Low levels of fat absorption were found 4 and 8 weeks after the initial operation in group A. The coefficient of absorption of the different fatty acids showed complete absorption of caprylic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Case-Control Studies↗
PubMed1995

Pulmonary neuroendocrine cells in neonatal rats with congenital diaphragmatic hernia.

Lung hypoplasia and persistent pulmonary hypertension are the principal causes of high mortality and morbidity in infants with congenital diaphragmatic hernia (CDH). Amine- and peptide-producing pulmonary neuroendocrine cells (PNEC), widely distributed throughout the airway mucosa, are thought to play an important role in both pulmonary development and regulation of pulmonary vascular tone. Furthermore, recent studies show increased levels of calcitonin gene-related peptide (CGRP), a pulmonary vasodilator produced by PNEC, during chronic hypoxia. The article reports data on morphometric analysis of CGRP immunoreactive PNEC clusters (neuroepithelial bodies, NEB) in a rat model of CDH. CDH was induced in neonatal Sprague Dawley rats by oral administration of 2,4-dichloro-phenyl-p-nitrophenylether (Nitrofen; Rohm Haas, Philadelphia, PA) to the mother at 10 days of gestation. Sections of lungs from term neonatal rats with and without CDH and controls were immunostained for CGRP (marker of NEB) with specific antibody against rat CGRP. NEB size and number of NEB/area of lung were assessed using a semiautomatic image analysis system. In lungs of neonatal rats with CDH, the number of NEB per surface area of lung parenchyma was significantly increased compared with the age-matched controls. Although the mean size of NEB was larger in CDH, the differences were not significant. This is the first study of PNEC in CDH. Whether the phenomenon observed in this study results in altered NEB function including imbalance in vasoactive mediators requires further studies, especially in the human being.

Animals↗
PubMed1995

A lack of intestinal pacemaker (c-kit) in aganglionic bowel of patients with Hirschsprung's disease.

Recent experimental studies in mice have shown that the proto-oncogene c-kit plays a key role in the development of a component of the pacemaker system that is required for generation of autonomic gut motility. These studies further suggest that interaction of the c-kit receptor and its ligand (stem cell factor, SCF) is critical for the development of the enteric nervous system. The authors investigated the presence of c-kit-positive (c-kit+) cells as well as the expression of SCF in bowel from 12 patients with Hirschsprung's disease (HD), 4 patients with total colonic aganglionosis (TCA), 2 patients with extensive aganglionosis (EA) and 14 controls. Our methods involved the use of immunohistochemistry with antihuman c-kit sera and antihuman SCF sera. A few c-kit+ cells were found in the muscle layers of aganglionic bowels from HD, TCA and EA, in contrast to many c-kit+ cells in ganglionic bowel segments from control, HD, and TCA patients. Expression of SCF was identified in the muscle layers as well as in myenteric plexus of ganglionic bowel, in contrast to its absence in the muscle layers of aganglionic bowel specimens. A lack of c-kit and SCF might be of significance for autonomic gut dysmotility in aganglionic bowel segments of patients with HD and allied disorders such as chronic idiopathic intestinal pseudo-obstruction.

Cell Adhesion Molecules↗
PubMed1995

Rotation of the gut: fact or fantasy?

Clinicians, as well as embryologists, believe that normally a process of rotation of the midgut takes place that can be hampered at any stage resulting in the different types of "malrotations." However, a "malrotated" gut has never been observed in normal embryos. Therefore all theories on the normal and abnormal development of the gut are still highly hypothetical. In an attempt to elucidate more clearly which events occur during the development of the gut, the authors studied its embryology in 58 normal rat embryos between the 13th and 20th day of gestation using scanning electron microscopy. In 13 day old rat embryos, the midgut has already formed a loop. It can be subdivided into three parts: the central part with its connections to the stomach and leading to the straight part, with the colorectum on the left and the "small bowel" on the right, and the tip of the loop inside the umbilical cord. These three parts show no signs of developmental synchronization. Each part develops according to its own developmental blueprint: the duodenal and umbilical parts of the midgut show much developmental activity, whereas gross changes of the straight part of the midgut are not seen. This finding is surprising because a process of rotation, if occurring, should result in notable morphological changes especially in this region. Furthermore, the coecum never achieved a position in the upper left abdomen, as is often outlined in schematic drawings. After the return of the bowel into the abdominal cavity, the coecum lies exclusively on the right side of the midline close to the ventral abdominal wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Factors influencing whether or not couples seek genetic counselling: an explorative study in a paediatric surgical unit.

To investigate the factors influencing whether or not couples seek genetic counselling, the parents of 37 children with a major congenital anomaly were interviewed at home. All the children had been admitted to the Intensive Care Unit (ICU) of the Department of Paediatric Surgery. After physical examination of the child, the consultant clinical geneticist stated that genetic counselling was indicated for the parents. Whether they sought genetic counselling was left to the parents to decide. Eighteen of the 37 parents had sought genetic counselling. Assessment of the joint influence of a number of factors revealed that two factors were separately paramount in distinguishing between couples who did seek genetic counselling and those who did not: whether parents considered genetic counselling useful in their case shortly after the birth of their affected child, and whether the couple was clearly and correctly informed about the indication for genetic counselling. The intention to have a subsequent pregnancy was not associated with whether or not couples sought genetic counselling. Loss of information was observed: 1/3 of the referrals for genetic counselling mentioned on the written consultation forms were not stated in the discharge letters. This loss of information could have been reduced by a) routinely including the indication for genetic counselling in the discharge letter and b) appointing a coordinating physician to ensure that the parents were informed clearly about the availability of genetic counselling. Resistance to genetic counselling needs to be respected by the physician. Exploring its background might help to reduce this resistance.

Attitude to Health↗
PubMed1994

Inhibition of T3-receptor binding by Nitrofen.

Lung development is controlled by various hormones, including thyroid hormone. The herbicide 2,4-dichlorophenyl-p-nitrophenyl ether (Nitrofen) induces lung hypoplasia in fetal rats, when administered to the mother during gestation. Nitrofen might be teratogenic by an anti-thyroid activity. The present study shows that Nitrofen decreases the binding of T3 to the alpha 1 and beta 1 form of the thyroid hormone receptor in a non-competitive way. Consequently, rat lung hypoplasia might result from the decreased binding of T3 to its receptor, via exposure to Nitrofen during fetal development.

Animals↗
PubMed1994

Etiological aspects of congenital diaphragmatic hernia: results of a case comparison study.

We report the results of a parental questionnaire concerning possible etiological and teratological factors, such as exposure to herbicides, in the development of congenital diaphragmatic hernia (CDH). The herbicide Nitrofen interferes with lung development in rats, can induce diaphragmatic hernia and greatly resembles thyroid hormone. No association with the studied teratogens nor with maternal thyroid dysfunction was found. The questionnaire was completed by 33 parents whose baby had CDH, and by 43 couples whose baby had oesophageal atresia. The resemblance of Nitrofen to thyroid hormone, a well-known growth factor for the developing lung, is of particular interest from a pathogenetic point of view in the development of CDH.

Case-Control Studies↗
PubMed1994

Gas exchange across native lungs and extracorporeal membrane in neonates and pigs during extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) is a commonly used treatment modality for severe neonatal respiratory failure. The aim of the present study was to evaluate the relationship between ECMO blood flow and gas exchange across the native lungs and the extracorporeal membrane. In three healthy pigs, the ECMO flow correlated significantly with oxygen transfer (VO2) across the membrane (n = 12, r = .90, P < .001) and inversely with VO2 across the lungs (n = 12, r = -.75, p < .005). In three pigs with acute respiratory distress syndrome induced by repeated bronchoalveolar lavage, flow also significantly correlated with VO2 across the membrane (n = 9, r = .93, P < .001) and inversely with VO2 across the lungs (n = 9, r = -.97, P < .001). Eight neonates had measurements taken at different time intervals and different flow rates during ECMO. The ECMO flow correlated significantly with VO2 across the membrane (n = 45, r = .61, P < .001) and inversely with VO2 across the lungs (n = 15, r = -.54, P < .05). The relationship between carbon dioxide transfer (VCO2) and ECMO flow rates had the same trend as VO2 on all occasions. It is concluded that the ECMO flow rate is one of the main determinants of gas exchange across the lungs and the membrane.

Animals↗
PubMed1994

Tracheal agenesis.

Agenesis of the trachea is a rare anomaly. The main signs are respiratory distress and cyanosis, inability to vocalize and impossible tracheal intubation. In most cases concomitant congenital anomalies of the heart, digestive tract or genitourinary tract are present. Endoscopy and X ray studies will confirm the diagnosis. There is no long-term surgical solution because no suitable material for a tracheal prosthesis is available at present, therefore the condition is ultimately fatal. We report a case of tracheal agenesis. After the diagnosis was established the baby's lungs were ventilated for several hours via an oesophageal tube and two broncho-oesophageal fistulae, but she finally died from untreatable respiratory acidosis. Autopsy revealed a Floyd's type III tracheal agenesis and a laryngeal cleft.

Acidosis, Respiratory↗
PubMed1993

The distribution and characterization of HNK-1 antigens in the developing avian heart.

The heart originates from splanchnic mesoderm and to a lesser extent from neural crest cells. The HNK-1 monoclonal antibody is a marker for early migrating neural crest cells, but reacts also with structures which are not derived from the neural crest. We investigated whether heart structures are HNK-1 positive before neural crest cells colonize these target tissues. To that end, we determined the HNK-1 antigen expression in the developing avian heart on immunohistochemical sections and on Western blots. The HNK-1 immunoreactivity in the developing chick heart is compared with data from literature on the localization of neural crest cells in chick/quail chimeras. Structures with neural crest contribution, including parts of the early outflow tract and the related endocardial cushions, the primordia of the semilunar valve leaflets and the aorticopulmonary septum were HNK-1 positive. Furthermore, other structures were HNK-1 positive, such as the atrioventricular cushions, the wall of the sinus venosus at stage HH 15 through 21, parts of the endocardium at E3, parts of the myocardium at E6, and the extracellular matrix in the myocardial base of the semilunar valves at E14. HNK-1 expression was particularly observed in morphologically dynamic regions such as the developing valves, the outflow tract cushion, the developing conduction system and the autonomic nervous system of the heart. We observed that atrioventricular endocardial cushions are HNK-1 positive. We conclude that: a HNK-1 immunoreactivity does not always coincide with the presence of neural crest cells or their derivatives; (2) the outflow tract cushions and atrioventricular endocardial cushions are HNK-1 positive before neural crest cells are expected (stage HH 19) to enter the endocardial cushions of the outflow tract; (3) the observed spatio-temporal HNK-1 patterns observed in the developing heart correspond with various HNK-1 antigens. Apart from a constant pattern of HNK-1 antigens during development, stage-dependent HNK-1 antigens were also found.

Animals↗
PubMed1993

Regional differences between various axial segments of the avian neural crest regarding the formation of enteric ganglia.

The vagal neural crest adjacent to somites 1-7 gives rise to the enteric ganglia along the entire digestive tract. It is generally assumed that formation of enteric ganglia in preumbilical gut is independent of the axial segment from which the neural crest originates. In post-umbilical gut, however, there is evidence that the axial segment of origin of the neural crest might be relevant to neural differentiation. In this part of the gut, we previously identified a subpopulation of HNK-1-immunoreactive cells within the enteric mesenchyme. This immunoreactivity disappeared upon formation of the enteric nervous system. We studied the interaction between various axial segments of quail neural crest and the microenvironment in a neural chicken hindgut using chorioallantoic membrane cocultures. We found that neural crest cells from various axial segments could migrate into the gut and home to the correct sites. However, whereas vagal neural crest cells differentiated into enteric neurons, neural crest cells from truncal segments mainly differentiated into melanocytes. The HNK-1-immunoreactivity within the enteric mesenchyme only disappeared when neural crest cell colonization was followed by differentiation into enteric neurons and subsequent formation of enteric ganglia. To determine whether differentiation of neural crest cells in chorioallantoic membrane cocultures was influenced by the prolonged presence of the neural tube and notochord, we developed a new coculture system, using neural crest cells cultured in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Avoidance of emergency surgery in newborn infants with trisomy 18.

Trisomy 18 (Edwards' syndrome) presents with characteristic external features as well as life-threatening abnormalities; many of these abnormalities require surgical correction during the neonatal period. Children with trisomy 18 have a very short life expectancy, and all long-term survivors have severe mental retardation. Difficult medical and ethical issues arise over whether or not to institute treatment when a newborn infant with suspected trisomy 18 has a life-threatening anomaly. We studied the policy of treatment in seven patients with clinical Edwards' syndrome. For three, the period of uncertainty was shortened because trisomy 18 was rapidly diagnosed by karyotyping of a bone-marrow aspirate. Four of the patients underwent surgery before the diagnosis of trisomy 18 was confirmed by routine karyotyping in lymphocytes; karyotyping in bone marrow might have allowed invasive treatment to be avoided in three of these. Rapid confirmation of clinically suspected Edwards' syndrome is very important because surgery may then be withheld. A newborn infant with trisomy 18 should be considered as a patient with a hopeless outlook who ought not to be subjected to invasive procedures. The decision to withdraw or withhold treatment should be discussed frankly with the parents. The period of uncertainty can be reduced to a minimum by the use of karyotyping in bone marrow.

Abnormalities, Multiple↗
PubMed1992

Cardiopulmonary resuscitation in paediatric intensive care patients.

To identify the success of cardiopulmonary resuscitation in the paediatric ICU patient we undertook a retrospective study in an 11-bed medical and a 14-bed surgical paediatric ICU over a 32-month period. Thirty-four patients suffered an arrest in the ICU. Only 4 patients could be resuscitated successfully; 1 died after 24 h. Of the 3 long-term survivors 1 suffered from severe neurologic sequelae. All patients were in CCS classes III or IV. All but 3 patients had PSI scores greater than 8. The decision to resuscitate or to withhold therapy in individual patients who are deteriorating in the course of a critical, preceding illness should not be based on the risk index of these scoring systems. Both medical and ethical considerations should be guidelines in the process of decision-making.

Adolescent↗
PubMed1992

Colonization characteristics of enteric neural crest cells: embryological aspects of Hirschsprung's disease.

This study explores the development of the enteric nervous system in avian embryos. Particular emphasis was given to colonization characteristics of neural crest cells present in primitive enteric ganglia. By coculturing neuronal and aneuronal gut of quail and chicken embryos, we investigated if and when neural crest cells in primitive enteric ganglia could detach from these ganglia, migrate, and colonize adjacent chicken gut. Quail neural crest cells were identified using the quail nucleolar marker and the HNK-1 antibody. Enteric neurons were identified using three monoclonal antibodies directed against neurofilament proteins. We found that neural crest cells detached from primitive ganglia in neuronal quail gut from E6 till E9, whereas neural crest cells did not leave enteric ganglia from E10 gut. These observations show that there is a transient phase during which enteric neural crest cells can leave the gut. To determine whether neural crest cells could colonize neuronal gut we cocultured neuronal gut or the neural primordium and neuronal chicken gut (E11). We found that quail neural crest cells do not colonize neuronal E11 gut, whereas they do colonize aneuronal gut of the same age. We suggest that aneuronal gut attracts neural crest cells by diffusing factors.

Animals↗