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Biomedical subjects

M A van den Bergh Weerman

Publications and source records attributed to M A van den Bergh Weerman.

14 recordsLinked to original sources
PubMed2006

[Neonatal respiratory distress caused by primary ciliary dyskinesia].

Two newborns, both boys, presented with unexplained respiratory distress. One developed recurrent pneumonias in the first neonatal week and was diagnosed with primary ciliary dyskinesia at the age of 2.5 years. The other had respiratory problems besides a situs inversus totalis and was diagnosed with primary ciliary dyskinesia in the neonatal period. Although 65-90% of children with primary ciliary dyskinesia present with neonatal respiratory distress, the disease is often diagnosed after a considerable delay. Primary ciliary dyskinesia should be considered in newborns with unexplained respiratory problems and in children with recurrent respiratory problems. The disease is diagnosed by taking a nasal brush biopsy of the cilia and examining it using electron microscopy or using phase contrast microscopy. Early diagnosis and adequate treatment may prevent further lung damage.

Ciliary Motility Disorders↗
PubMed1997

The role of bile salt composition in liver pathology of mdr2 (-/-) mice: differences between males and females.

BACKGROUND/AIMS: The mouse mdr2 gene encodes a P-glycoprotein expressed in the canalicular membrane of the hepatocyte. Mice in which this gene has been inactivated (mdr2 -/-) show a defect in biliary phospholipid and cholesterol secretion and develop non-suppurative cholangitis. We hypothesized that secretion of bile salts without lipids initiates this liver disease. METHODS: To delineate the pathologic process, mdr2 (-/-) mice were fed different bile salt-supplemented diets for 22 weeks after weaning. Aspects of liver pathology including eosinophilic bodies, portal inflammation, ductular proliferation, mitotic activity and fibrosis were semi-quantitatively scored. RESULTS: It was observed that liver pathology was more severe in female than in male mice when fed a purified control diet. This correlated with a more hydrophobic bile salt composition of female vs. male bile. When increasing amounts of cholate were added to the diet (0.01% and 0.1%), the secretion of taurocholate increased and this was accompanied by a more severe liver pathology. At the high dose of cholate (0.1%), the bile salt compositions of male and female mice became similar, as did the severity of the histological score. Addition of cholate to the diet did not induce liver pathology in (+/+) mice. Addition of ursodeoxycholate to the diet (0.5%) led to a near complete replacement of biliary bile salts by tauroursodeoxycholate and this reduced pathology and dissipated the difference between males and females. CONCLUSIONS: These observations support our hypothesis that liver pathology in the mdr2 (-/-) mouse is caused by bile salts and depends on the hydrophobicity c.q. cytotoxicity of biliary bile salts.

Animals↗
PubMed1994

Developmental stages in experimental liver metastases: relation to invasiveness.

We have previously reported that an invasive morphotype can be evoked in a rat colon carcinoma by transplanting it into pre-induced subcutaneous granulation tissue. We have now studied the interaction of the same tumor with liver tissue, which is extremely poor in connective tissue in comparison with the subcutaneous site. Tumor cells were injected into the portal system and the resulting experimental liver metastases were examined by electron microscopy and immunohistochemistry. Early metastases consisted of well-differentiated acini, fully surrounded by connective tissue that was derived from the periportal stroma. In a later stage, this connective tissue was overgrown by tumor cells and, almost immediately, acinar differentiation was lost. Most metastases eventually reached the liver capsule, which reacted by forming a layer of granulation tissue. Only in this layer, we observed invasion by thin tumor cell strands, which were often intimately associated with fibroblasts or with blood capillaries. The tumor cells remained smooth and rounded during this process. After fully penetrating the granulation tissue, the tumor cell strands reached the liver surface, where they formed poorly structured papillary masses that were nearly devoid of stroma. Our observations indicate that, even in a relatively homogeneous organ like the liver, the tumor-host interaction is highly complex and dynamic. They also confirm the notion that granulation tissue stimulates tumor invasiveness. Finally, they show that tumor cells can actively invade host tissues without exhibiting a "fibroblastic" morphology.

Animals↗
PubMed1994

Septata intestinalis frequently isolated from stool of AIDS patients with a new cultivation method.

Two species of microsporidia, Enterocytozoon bieneusi and Septata intestinalis have been reported as intestinal parasites of AIDS patients. In attempts to establish E. bieneusi in vitro, spores were concentrated from stool samples from 4 AIDS patients with biopsy-proven E. bieneusi infections. After sterilization of the concentrate in antibiotic solution, the spores were added to monolayers of RK13 cells grown on the membranes of Transwells. Cultures were established from 7 stool samples from the 4 patients but in every case the species established was S. intestinalis not E. bieneusi. On retrospective examination of the stools, a very small number of spores of a size comparable to that of S. intestinalis was found but this species was not detected in biopsies. Typical septate vacuoles containing Type I tubules were observed in vitro but in contrast to the original description, meronts were intravacuolar and sporogony was mainly disporoblastic. The cultivation system, used for the first time for microsporidia, revealed the presence of unsuspected S. intestinalis infections and indicates that this species may be much more common than hitherto suspected. S. intestinalis has not previously been cultured.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Mice with homozygous disruption of the mdr2 P-glycoprotein gene. A novel animal model for studies of nonsuppurative inflammatory cholangitis and hepatocarcinogenesis.

The mouse mdr2 gene (and its human homologue MDR3, also called MDR2) encodes a P-glycoprotein that is present in high concentration in the bile canalicular membrane of hepatocytes. The 129/OlaHsd mice with a homozygous disruption of the mdr2 gene (-/- mice) lack this P-glycoprotein in the canalicular membrane. These mice are unable to secrete phospholipids into bile, showing an essential role for the mdr2 P-glycoprotein in the transport of phosphatidylcholine across the canalicular membrane. The complete absence of phospholipids from bile leads to a hepatic disease, which becomes manifest shortly after birth and shows progression to an end stage in the course of 3 months. The liver pathology is that of a nonsuppurative inflammatory cholangitis with portal inflammation and ductular proliferation, consistent with toxic injury of the biliary system from bile salts unaccompanied by phospholipids. Thus, the mdr2 (-/-) mice can serve as an animal model for studying mechanisms and potential interventions in nonsuppurative inflammatory cholangitis (in a generic sense) in human disease, be it congenital or acquired. When the mice are 4 to 6 months of age, preneoplastic lesions develop in the liver, progressing to metastatic liver cancer in the terminal phase. The mdr2 (-/-) mice therefore also provide a tumor progression model of value for the study of hepatic carcinogenesis. Interestingly, also in this regard, the model mimicks human disease, because chronic inflammation of the biliary system in humans may similarly carry increased cancer risk.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1993

Diagnosis of intestinal and disseminated microsporidial infections in patients with HIV by a new rapid fluorescence technique.

AIMS: To assess the value of a new rapid fluorescence method for the diagnosis of microsporidiosis in HIV seropositive patients. METHODS: Microsporidian spores in stools were demonstrated by using the fluorochrome stain Uvitex 2B. The new technique was evaluated in three groups of HIV seropositive patients with diarrhoea. Group 1: 19 patients with biopsy confirmed E bieneusi infection (186 stool samples); group 2: 143 consecutive patients from whom faeces were submitted for routine investigation of diarrhoea (318 samples); group 3: 16 patients with small intestinal biopsy specimens negative for microsporidia (55 samples). The new method was used to monitor spore shedding during experimental treatment with paromomycin and albendazole in four patients. RESULTS: Brightly fluorescent spores were detected in all stool samples of patients in group 1. In group 2 16 (11%) patients had spores in their stool samples. E bieneusi was found in 11 patients; in the other five another genus of microsporidia, Encephalitozoon, was recognised. Encephalitozoon spores were also found in the urine of three of these patients and in the maxillary sinus aspirate of two of them, suggesting disseminated infection. The results were confirmed by electron microscopic examination. In group 3 negative biopsy specimens were confirmed by negative stool samples in all cases. Treatment with albendazole and paromomycin did not affect the spore shedding in three patients with E bieneusi infection. By contrast, in a patient with Encephalitozoon sp infection albendazole treatment resulted in clinical improvement together with complete cessation of spore excretion in the stool. CONCLUSION: The Uvitex 2B fluorescence method combines speed, sensitivity, and specificity for the diagnosis and treatment evaluation of intestinal and disseminated microsporidiosis.

Albendazole↗
PubMed1987

Heterogeneity of lung cancer: the problem of sample error in diagnostic electron microscopy.

We studied the ultrastructure of superficial and deep samples of 40 resected primary lung carcinomas. Tumour cell differentiation was semiquantitatively assessed and differences between samples of a same tumour were evaluated. In two instances were major differences in ultrastructural diagnosis found between the samples of the same tumour. A further 9 cases showed one predominant differentiation in one sample, but two equally predominant differentiations in the second sample. The other 29 tumours did show occasional minor differences between the samples, but these differences did not result in differences in ultrastructural diagnosis.

Carcinoma, Small Cell↗
PubMed1984

Rapid deparaffinization for electron microscopy.

The authors present a method by which the number of steps required for the ultrastructural study of material originally embedded in paraffin can be greatly reduced. The process reduces deparaffinization, post-fixation, and re-embedding to four steps that take little more than 30 min to complete.

Adenocarcinoma↗
PubMedDate not supplied

Angulate lysosomes.

Under many circumstances, macrophages accumulate lipids (possibly in combination with other materials) in the form of micelles that by their rigidity and size impart an irregular, angulate shape to the lysosomes in which they are stored. When macrophages contain large numbers of these angulate lysosomes, they have a characteristic light microscopic appearance and are often designated Gaucher cells or Gaucher-like cells. In most instances, however, the angulate lysosomes are small in number or size and are not easily recognized by light microscopy. A search of the literature and our own files revealed angulate lysosomes in a considerable number of conditions in which they have not previously been observed or recognized. In most conditions, the evidence indicates that the material stored is derived from phagocytosed cells that are incompletely digested, either because they are simply too numerous to be handled by the macrophage or due to a primary metabolic deficiency, or both. In contrast to what has been assumed, angulate lysosomes not only arise in situations in which blood cells are phagocytosed, but also when various types of degenerating tumor cells, remnants of myelin sheaths, or bacteria accumulate inside macrophages. In yet other conditions, the origin of the lysosomal contents remains to be elucidated.

Brain Diseases↗
PubMedDate not supplied

Ultrastructure of the liver in th cerebrohepatorenal syndrome of Zellweger.

Three infants with clinical and biochemical features of Zellweger's cerebrohepatorenal syndrome are presented, and the ultrastructural features of successive biopsy and autopsy liver specimens are described. No hepatocellular peroxisomes were found in these patients on routine electron microscopy or electron microscopic histochemistry. In a control group of liver biopsies from 9 patients with other pediatric liver diseases, peroxisomes were readily identifiable in each hepatocyte. Apart from the absence of peroxisomes, the hepatocytes had a remarkably "normal" aspect, even in the final stages of the disease. Mitochondrial abnormalities, which have been the subject of some controversy in this syndrome, were a highly variable and inconstant finding in our cases. We draw attention to another ultrastructural feature of the syndrome, namely the occurrence of large angulate lysosomes, containing conspicuous double lamellae, inside macrophages, which were especially abundant in later stages of the disease. These angulate lysosomes may be of additional value in the ultrastructural diagnosis of Zellweger's syndrome, especially when only poorly preserved liver tissue (e.g., paraffin-embedded or postmortem material) is available, and the absence of peroxisomes is difficult to assess. In these instances, the angulate lysosomes can still be identified with ease.

Brain Diseases↗
PubMedDate not supplied

Rapid contrasting of extracellular elements in thin sections.

Standard methods for contrasting ultrathin sections generally have their greatest effect on cells and cellular components, whereas extracellular elements remain relatively electron-lucent. Occasionally, some extracellular elements even fail completely to react with the staining solutions. We describe a method for rendering a uniformly high contrast to extracellular tissue components. This consists of a brief prestaining of grids with diluted tannic acid in distilled water. Simple, rapid, and versatile, this procedure can be routinely applied to all tissue samples examined by electron microscopy. As an additional advantage, the method greatly enhances the electron density of intracellular glycogen. Higher concentrations of tannic acid give increased electron density, especially to elastin, and can therefore be used as an elastin stain.

Collagen↗
PubMedDate not supplied

Electron microscopy as an essential technique for the identification of parasites in aids patients.

We use EM with increasing frequency for the identification of opportunistic parasitic infections in HIV-infected individuals. Apart from Pneumocytis carinii, Toxoplasma, Cryptosporidium, and Leishmania, we studied several aspects of microsporidiosis. Infection with the intestinal microsporidian Enterocytozoon was found in as much as 27% of AIDS patients with chronic diarrhoea without other pathogens. EM diagnosis of microsporidiosis is commonly performed on intestinal biopsies, but we have recently demonstrated spores of microsporidium with a non-invasive technique, viz. in faeces (1). However, EM of biopsy material remains the reference technique to distinguish the various species. Combining faeces and biopsy examination, we identified another group of microsporidians, Encephalitozoon sp., in the small intestine of AIDS patients with chronic diarrhoea (Fig. 1). Encephalitozoon sp. with identical ultrastructure was found in urine and sinus discharge, suggesting dissemination of the infection. In the maxillary sinus of one patient, we demonstrated E. bieneusi, a parasite which had previously been found only in small intestine and bile duct epithelium (2) (Fig. 2). After albendazole treatment, Encephalitozoon sp. disappeared from faeces, urine and nasal discharge. Although ultrastructural damage was noted in the developmental cycle of E. bieneusi in biopsies after treatment with albendazole, spores continued to be present in the faeces. These results demonstrate the great value of EM in the diagnosis of several parasitic diseases, especially microsporidiosis.

AIDS-Related Opportunistic Infections↗