Biomedical subjects
Publications and source records attributed to V Desmet.
A 33-year-old woman presented a recurrent steroid-sensitive protein-losing enteropathy as the major manifestation of systemic lupus erythematosus. An increased capillary permeability for proteins is considered to be the most likely explanation.
Various fixation and staining procedures for the demonstration of surface and cytoplasmic antigens have been described. An immunostaining procedure was sought that would allow the demonstration of these antigens, especially in small human tissue samples at the ultrastructural level. A modification and adaptation of the technique of Eldred, Zucker, Karten, and Yazula (J Histochem Cytochem 31:285, 1983) was applied on several varieties of human tissue, including liver, skin, and lymphoid tissue, using monoclonal and polyclonal antibodies in an indirect peroxidase procedure. In this way a reliable and generally applicable procedure was developed that satisfied the following demands: Use of a universal fixative that allows preservation of the antigenicity of various antigens; Adequate penetration of the tissue by the immunological reagents; Optimal preservation of subcellular structures; and Possibility to store the tissue samples for considerable periods of time.
BALB/c mice were immunized with S-100 protein, which was isolated from bovine brain. The first fusion resulted in the cloning of three stable hybridoma lines (S1-61-64, S1-61-65, S1-87-4) that produced monoclonal antibodies against S-100 protein. The hybridoma lines obtained from a second fusion (S2-20, S2-95) were not stable and antibody production ceased early during cloning. Immunoblotting results showed that all antibodies reacted with antigenic determinants shared by both the alpha- and beta-subunit of S-100 protein. These antigenic sites appeared to differ from the calcium-binding site since immunoblotting against other calcium-binding proteins sharing this site (calmodulin, carp parvalbumin, oncomodulin) was negative. Despite the fact that the immunoblotting reactions of the antibodies obtained from both fusions were indistinguishable, different immunohistologic labeling patterns could be observed. These antibodies have proven to be excellent reagents for the immunocytochemical detection of S-100 in normal and pathologic human tissue.
The distribution of B- and T-lymphocytes, of OKIa positive cells, and of HLA-ABC antigens in the normal cornea was investigated using monoclonal antibodies. The lymphocytes and Langerhans cells are present mainly in the well-vascularized limbic region but also occur albeit in small number in the center of the cornea. HLA-ABC antigens are strongly expressed on the epithelial cells of the cornea and the limbus.
Hepatic lymphangioma is an extremely rare benign tumor, which usually occurs as part of a multiorgan lymphangiomatous involvement. We describe an adult patient with a huge hepatomegaly caused by a diffuse lymphangiomatous infiltration of the liver, which has never been reported before. Extrahepatic localizations could not be demonstrated. On ultrasonography and computed abdominal tomography, the liver lesions were not distinguishable from necrotic metastases. However, the endoscopic and histologic picture as well as the benign clinical evolution during a 2-yr follow-up allowed us to diagnose this rare benign disorder.
Hepatic histologic materials (biopsy or autopsy) and associated clinical data from 155 hemophiliacs were collected by an ad hoc hemophilia study group and analyzed retrospectively in an effort to determine the spectrum of liver disease in this population and to examine the relationship between the severity of liver disease and treatment history. Clinical information on the frequency of complications from 126 biopsies in 115 hemophilic patients provided a unique opportunity to assess the safety of liver biopsy in such patients. The incidence of cirrhosis (15%) and chronic active hepatitis (7%) was lower than previously reported. The frequency of severe liver disease (chronic active hepatitis or cirrhosis) in patients receiving large pooled concentrates was no greater than in patients treated principally with cryoprecipitate or plasma. The risks of liver biopsy in this setting are relatively high: clinically significant hemorrhage followed 12.5% of the procedures.
The effect of 15(R)-15 methyl PGE2 on the evolution of gastric ulcers induced by endoscopic Nd:YAG laser photocoagulation was studied. By continuous application of 50 to 70 watt power for 4 sec at a distance of 15 mm from the gastric mucosa, reproducible ulcers can be induced. The effect of the drug in nonantisecretory doses (10 micrograms/kg) on the acute ulcer formation and on the healing rate was evaluated in mongrel dogs by light microscopy. Local administration or oral pretreatment did not influence the size or depth of acute ulcers (7.4 mm in diameter) as compared to a control series (7.2 mm). Pretreatment for several days, however, had a marked beneficial effect on the healing rate of the ulcers (1.71 mm after 7 days compared to 2.76 mm for the control series). From these data it may be concluded that 15(R)-15 methyl PGE2 has a beneficial effect on ulcer healing, even in nonantisecretory doses.
Using monoclonal antibodies on fresh frozen endoscopically obtained oesophageal biopsies the distribution of Langerhans cells, B lymphocytes, and various subpopulations of T lymphocytes was studied in the normal human oesophageal mucosa and in oesophagitis. Identification of the lymphocytes was carried out by an immunoperoxidase technique using OKT3 (antihuman T cell antibody), OKT4 (antihuman helper T cell antibody), OKT8 (antihuman cytotoxic T cell) and OKT10 (antihuman null cell antibody). Identification of the Langerhans cells was carried out using an ATPase stain and OKIa (Ia like antigen) and OKT6 (antihuman thymocyte). In the normal oesophageal epithelium cytotoxic T lymphocytes are found as well as Ia positive Langerhans cells. Helper T lymphocytes and B lymphocytes are present mainly in the lamina propria. In oesophagitis an increase in Langerhans cells and cytotoxic T lymphocytes within the epithelium is found. From these findings it can be concluded that the oesophagus contains a reticuloepithelial system as well as a lymphocytic population which are a part of the gut-associated lymphoid tissue.
A histological study was performed on liver biopsies from patients with acute hepatitis A (n = 13), B (n = 35) and non-A, non-B (nAnB) (n = 35) in search for microscopical features characteristic for each type of hepatitis. Biopsies from two centres (Padova, Italy and Leuven, Belgium) were studied in order to determine whether the histological pattern in acute hepatitis A, B and nAnB may differ from one centre to another. The histology of cases of hepatitis A and B from Italy and Belgium did not differ. Less liver cell plemorphism was found in hepatitis A than in B. Clear differences were observed between acute hepatitis nAnB occurring in Padova when compared with cases from Leuven. The Padova-biopsies obtained from patients with transfusion-induced viral hepatitis were mainly characterized by a high degree of lympho-histiocytic intrasinusoidal infiltration whereas the Leuven-biopsies, mostly taken in patients with sporadic hepatitis, were characterized by the presence of numerous acidophilic bodies and Mallory body-like cytoplasmic alterations. Morphologically, the latter cases appear to be closely related to hepatitis B.
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Using freeze-fracture techniques the junctional complex of the hepatocytes in female rats is studied after ethinyl estradiol induced cholestasis. The gap junctions are not changed in this situation in contrast to the altered pattern found in extrahepatic bile duct obstruction. The more or less parallel tight junctional strands around the canalicular lumen are converted into a irregular loose network after estradiol treatment in a similar way as in extrahepatic cholestasis. These modifications in the geometrical arrangement of the strands suggest an increase permeability through the tight junctions so that a backward diffusion of biliary components through intercellular escape is possible.
The histochemical activity of gamma-glutamyl transpeptidase is examined in human liver biopsy specimens in normal and pathological conditions. Different histochemical patterns can be recognized. In histologically normal liver a faint sinusoidal membrane staining is observed. In pathological liver tissue invariably a pronounced canalicular gamma-GT activity is detected in addition to the faint sinusoidal membrane activity. The canalicular staining pattern is variable in extent and staining intensity, without clear correlation with specific disease entities. Cases with severe degrees of cholestasis, however, show a "washed-out" appearance of the tissue, apparently parallel to the degree of cholestasis. This phenomenon may be explained by the detergent action of bile salts accumulating in cholestatic tissue.
Ultrastructural investigation of liver biopsies from two patients with non-A, non-B hepatitis revealed cytoplasmic and nuclear alterations in the hepatocytes. The lesions in both patients, one with acute and one with chronic hepatitis, were similar and distinct from those previously described in other forms of hepatitis. These findings are compared with the reported findings in chimpanzee liver after inoculation with non-A, non-B infective material. The intranuclear findings are similar to the aggregations of 20-27 nm particles described in some infected chimpanzees, and the cytoplasmic alterations seem to be similar to the cytoplasmic structures and tubular arrangements reported in other inoculated chimpanzees. A striking finding of this study is the presence of both alterations together in the same biopsy in two different patients, suggesting that they represent a different stage of viral infection or different parts of the viral agent. It still remains to be proved that the ultrastructural particles indeed contain antigen(s) of the non-A, non-B hepatitis virus. The nuclear and cytoplasmic alterations are, however, characteristic for non-A, non-B hepatitis and are useful as ultrastructural hallmarks of this form of hepatitis.
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Clinical, microscopic, ultrastructural, and histochemical characteristics of a primary cutaneous tumor, identified as an APUDoma possibly arising from Merkel cells, are presented. The tumor can be diagnosed by means of routine histology. In some cases the argyrophylic staining technique can be helpful. The dermatological and histological aspects of this tumor suggest a highly malignant undifferentiated process. The biological behavior of this tumor, however seems to be of a low-grade malignancy. It is therefore important to recognize it from undifferentiated, highly malignant, mostly metastatic processes in the skin. There is also a summary of the clinical history and microscopic findings of identical tumors in 4 other patients.
The histologic features of esophagitis were studied in 18 patients with clinical evidence of reflux and in 20 normal subjects. Striking vascular changes were observed in addition to superficial acute inflammatory changes, basal zone hyperplasia, and close proximity of the stromal papillae to the epithelial surface. These lesions corresponded to endoscopically observed red points or strips of the esophageal mucosa. These vascular phenomena probably represent the first sign of esophagitis recognizable endoscopically as well as histologically.