Biomedical subjects
Publications and source records attributed to D Kluth.
Peptic complications in duplications of the alimentary tract may occur when the duplication is lined by gastric mucosa. These complications commonly develop in the first year of life. We report a case of a bleeding esophageal duplication in a fetus.
In the past, several theories have been proposed to explain the occurrence of anorectal malformations. Most investigators believe that these malformations are the result of an impaired process of septation. However, in 1986 vd Putte challenged all theories that tried to explain anorectal malformations by a faulty fusion of lateral ridges of the cloaca. To elucidate the principles of normal and abnormal cloacal development, the authors studied the morphology of this region in normal embryos of rats and abnormal embryos of SD mice, which often have abnormal cloacas. Using scanning electron microscopy (SEM), 245 normal rat embryos and 80 abnormal SD-mice embryos were observed. The results were as follows. (1) In normal embryos the region of the future anal opening can be identified soon after the establishment of the cloacal membrane. This part is a fixed point in cloacal development. (2) In abnormal embryos the cloacal membrane is too short. The region of the future anal opening is missing. (3) In abnormal embryos a spectrum of malformed cloacas can be observed. This is in accordance with the spectrum of anorectal malformations clinically observed in humans. (4) The authors' observations support recent findings that the "fistula" in anorectal malformations resembles a normal anus at an ectopic position.
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)
Since May 1990 we have treated 35 patients with spontaneous pneumothorax and without underlying lung disease by thoracoscopic operation. All patients entered a prospective trial. There have been four recurrences during a minimum follow-up of 7 months (median 19 months). Two complete collapses had had only fibrin glue sealant without any resection of bullae. The others were partial relapses not requiring any treatment. There was a striking high incidence of pain complaints and sensory disturbances (13 out of 29) even months after pleurodesis by coagulation or pleurectomy. Reduced trauma and less postoperative restriction of pulmonary function together with low recurrence rates suggest a more liberal indication in patients with their first manifestation of the disease. Nevertheless indication and choice of pleurodesis should be restrictive and be studied further for its specific complications.
Bleeding of an aneurysm--especially of a great vessel--represents a complication of Ehlers-Danlos syndrome that is often lethal. A successful operation of a symptomatic aneurysm of the superior mesenteric artery in a 12-year old girl with an Ehlers-Danlos syndrome type VI is reported. The aneurysm was resected and replaced by a venous graft. Four years postoperatively the artery is perfectly patent; a new aneurysm did not develop.
Disorders of intestinal rotation present with a wide spectrum of abnormalities. This variety is attributed to the puzzling embryology of the midgut. Clinicians, as well as embryologists, believe that normally a process of rotation of the midgut takes place which 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, we 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 already forms a loop. It can be subdivided into three parts: the central part (with its connections to rectum and stomach), 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). Obviously, these three parts show no signs of developmental synchronization. Each part develops according to its own developmental blue print: the duodenal and umbilical parts of the midgut show much developmental activity, while gross changes of the straight part of the midgut are missing. This finding is surprising because a process of rotation, if occurring, should result in notable morphological changes especially in this region. Further more, the coecum never achieved a position in the upper left abdomen, as it is often outlined by schematic drawings.(ABSTRACT TRUNCATED AT 250 WORDS)
Since January 1990 we have treated 49 patients with spontaneous pneumothorax (35 primary and 14 secondary cases) by thoracoscopic operation. All patients entered a prospective trial. Those with secondary pneumothorax are discussed here. There have been no major complications. Conversion rate however has been high with 4/14 (29%). Three more patients (21%) not suitable for thoracotomy suffered from persistent air leaks. The other 7 patients needed postoperative drainage for less than 6 days in average. VATS could nevertheless be an alternative to thoracotomy for avoiding prolonged suction treatment in patients with secondary pneumothorax as patients showed no complications or disadvantage after conversion to thoracotomy.
Until this study, 20 pathological-anatomic variants of esophageal atresia with a blind upper pouch and a distal tracheoesophageal fistula (type IIIb according to Vogt) had been described. The authors observed another variant, with the following characteristics: (1) an abnormally long lower segment that entered the trachea in the region of the upper thoracic aperture, (2) a long atretic proximal portion of the lower segment, and (3) an additional membrane in the lower segment. After resection of the atretic part of the lower segment and excision of the membrane, a primary anastomosis could be performed. This variant of type IIIb is characterized by a gasless abdomen.
Up to now, descriptions of the natural history of congenital diaphragmatic hernia (CDH) associated with pulmonary hypoplasia (PH) are based exclusively on observations made in the fetal period. However, nothing is known about the events that take place in an embryo with CDH. Recently, an animal model of CDH and PH has been established in rat embryos to study the embryology and natural history of this lesion. We exposed 36 pregnant Sprague-Dawley rats to a single dose of 100 mg nitrofen on day 11 of pregnancy. A total of 356 staged embryos and fetuses from day 13 to day 21 were studied by light and scanning electronmicroscopy. The litters of 9 untreated rats (124 normal age-matched embryos and fetuses) served as controls. The abnormal development of the diaphragmatic anlage was first seen in embryos aged 13 to 14 days. A defect appeared in the dorsal part of the diaphragm, normally on the right side. The liver grew through this defect early on. Gut was found in an intrathoracic position only in the very late stages (day 21/22) and newborns. Compared to controls, lungs of nitrofen-embryos with CDH were smaller, depending on the size of liver found in the thoracic cavity. Histologically, compression of lung was absent at these stages. Most authors speculate that CDH results because the pleuroperitoneal canals fail to close at the end of the embryonic period (ie, week 8 to 10 in human development) leading to a defect in the dorsolateral region of the diaphragm. However, contradictory to this assumption, our findings indicate that diaphragmatic defects develop in early embryonic life.(ABSTRACT TRUNCATED AT 250 WORDS)
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In infants with congenital diaphragmatic hernia (CDH), abnormalities of the pulmonary arteries are present consisting of increased medial wall thickness and decreased external diameter. This forms the morphological substrate for persistent pulmonary hypertension, one of the leading causes of the high mortality in these patients. To elucidate the significance of these abnormalities, experimental models are required that mimic as close as possible the human situation. In our rat model we are able to study the hypoplastic CDH lungs extensively. In this study we performed a histological evaluation of the pulmonary arterial bed in the control group and the nitrofen-treated group in which the latter was divided into two subgroups, CDH and normal diaphragm. We examined the newborn rats after perfusion of the pulmonary arteries with barium gelatine and subsequent fixation. At the level of the respiratory bronchioles significant differences in the vessels were found consisting of decreased external diameter and increased wall thickness as percentage of the external thickness in CDH lungs compared with controls. Abnormal muscularization of the peripheral branches of the CDH pulmonary arteries was also found. We concluded that the rat model strongly resembles the human situation concerning the arterial bed in the lungs.
Animal models for morphological investigations of anorectal malformations are barely known to pediatric surgeons. In this study the morphological characteristics of a spontaneous mutation of the house mouse, the so-called SD-mouse, are described. The semidominant gene SD exerts its influence on the anorectum, the urogenital system and the axial skeleton. Many heterozygous (SD/+) and all homozygous (SD/SD) animals die shortly after birth due to their malformations. Surviving heterozygotes, identified by their short and deformed tails, may be used for breeding purposes. According to Mendel's laws, mating of such heterozygous yields 75% more or less malformed animals which may be used for morphological investigations. The morphological features of these animals were investigated in 61 neonatal SD-mice (33 SD/SD, 28 SD/+) and in 10 normal controls by microdissection and in 49 animals (25 SD/SD, 20 SD/+ and four normal controls) by serial sections. Of these, all homozygous and 10 heterozygous SD mice had anorectal malformations. The spectrum of these malformations is wide: very complex malformations in SD/SD mice and high anorectal malformations in SD/+ mice. These are comparable to morphological features found in humans and piglets. Hence the SD mouse represents an animal model for morphologic and embryonic investigations of complex anorectal malformations.
In embryological terms, pathogenesis of congenital diaphragmatic hernia (CDH) associated with pulmonary hypoplasia is still unclear. However, it is known since 1971 that Nitrofen (2,4-dichloro-phenyl-p-nitrophenyl ether) can induce anatomical malformations in rats including diaphragmatic hernias. On order to establish an animal model of the embryogenesis of CDH, the effect of Nitrofen on the developing diaphragm was studied. Thirty-three pregnant female rats were exposed to Nitrofen. Five unexposed pregnant rats served as controls. In the first set of experiments, single doses of Nitrofen were given between the 9th and 13th day of pregnancy. In the second set of experiments, dosages of 50, 100, and 150 mg per animal were given on day 11 of pregnancy only. Postnatally the litters (469 newborn rats) were dissected to record the incidence of diaphragmatic malformations. The results were: (1) most hernias occurred after administration of 100 mg Nitrofen on day 9 (42%) and 11 (59%); (2) left-sided hernias were observed only after exposure to Nitrofen on day 9; (3) after exposure on day 10 or later all hernias were on the right side; and (4) Fifty-nine percent of the newborn rats exposed on day 11 had CDH. These results show that this model is suitable for further embryological investigations on the development of CDH.
Experiments to induce congenital diaphragmatic hernia (CDH) in rats, by means of administering a single dose of 2,4-dichlorophenyl-P-nitrophenyl (Nitrofen) on the 10th day of gestation, are reported here. Previously, congenital diaphragmatic hernia has been induced in sheep late in fetal development, and in mice early in gestation. The rat model, including a control group, was used to evaluate lung development and the presence of lung hypoplasia by morphometrical analysis. It was found that the single dose of Nitrofen, given 5 days before the normal closure of the diaphragm in the rat, leads to a high incidence of diaphragmatic hernia, mainly on the right side, and highly abnormal lung development (hypoplasia) comparable to the human situation. Both the lung weight/body weight index as well as the radial alveolar count were significantly lower in animals with CDH (P less than .05). This animal model offers a good opportunity to study abnormal lung development in relation to ventilatory capacity and pulmonary vascular reactivity.
The morphology of infraumbilical malformations suggests that the development of the genital anlage is of great importance for the embryology of the cloaca. In rat embryos the development of the genital anlage is documented using scanning electron microscopy. This documentation suggests that the genital anlage develops in three phases. Of these, the development of the unpaired glandular hillock seems to be especially important. The genital anlage affects the development of the cloaca in two ways: firstly its ventral growth causes a ventral shifting of the greater part of the cloaca into the region of the genitalia and secondly the cloaca gains its definite position through the development and growth of the glandular hillock.
The epithelial coating of the rectal pouch and fistula was studied morphologically in 33 newborn piglets with high and low forms of anal atresia and was found to be similar to the epithelial coating of the anal canal in normal piglets: the typical epithelium of the rectum changed its character into transitional epithelium at the region of the internal sphincter which surrounded the fistulae in all animals. In the caudal part of the fistula the transitional epithelium was followed by squamous epithelium. Only in male piglets with deformities and recto-urethral fistulae no squamous epithelium was found. In these cases transitional epithelium covered all parts of the fistula and the region of the internal sphincter. Anal glands were found in all animals, with or without anorectal malformations. They always invaded the internal sphincter. According to our morphological studies the fistula in anorectal malformations represents an ectopic anal canal.
A hypothesis in respect to the teratogenesis of bladder exstrophy and its variants is offered. The central feature of this hypothesis is the abnormal persistence of the caudal position of the insertion of the body stalk on the embryo. As a consequence of this, the normal advance and interposition of mesenchymal tissue to the midline becomes impossible. The cloaca cannot be translocated backwards into the body cavity, and the cranial end of the cloacal membrane remains in contact with the inferior aspect of the low-set body stalk. This, in contrast to the previously proposed abnormal rostral extension of the cloacal membrane, causes a wedge-effect resulting in the lateralization of the abdominal wall structures and also in the prevention of the midline fusion of the genital hillocks (labioscrotal or genital folds). A cloacal membrane normally is an unstable structure lacking mesoderm, and it retains these characteristics in the superficial and infraumbilical position to be described. It has a strong tendency to disintegrate. It may rupture at variable times and to a variable extent. The consequence of such an embryonic event is either a typical bladder exstrophy or one of the variants of the exstrophy malformation. Three different variants are presented that the proposed embryologic hypothesis can readily explain.
Most researchers believe that hypospadias arises from malformation of the penile urethra. However, this concept has been recently rejected, and it has been suggested that the opening of the urethra is "pushed forward" by growth of the perineum. In order to obtain more information on the development of the urethra, late stages of phallic development were studied in 220 rat embryos with scanning electron microscopy (SEM). In our study, signs of rupture of the urogenital membrane or fusion of the urethral folds could not be found. Therefore, we could not confirm the traditional concept for the development of the phallic urethra. A new concept of urethral development is suggested and the pathogenesis of hypospadias is discussed.