Brigitte A. Volk

Pancreatic lesions in the von Hippel-Lindau syndrome

Common manifestations of the von Hippel-Lindau syndrome, an autosomally dominant inherited cancer-prone disorder, include retinal angiomatosis, hemangioblastoma of the central nervous system, renal cysts, renal cancer, pheochromocytoma, and epididymal cystadenoma. Multiple cysts and microcystic (serous) cystadenomas of the pancreas have also been reported occasionally in patients afflicted with this syndrome. In the large Freiburg study of the von Hippel-Lindau syndrome composed of 66 affected individuals, pancreatic lesions were systematically studied. Fifty-five living individuals were examined by abdominal ultrasound imaging. Abnormal findings were confirmed by computed tomographic scan and/or magnetic resonance imaging. For an additional 11 decreased patients autopsy data were available. Cystic lesions of the pancreas were found in 10 patients (15%). One of these patients presented with multiple pancreatic cysts as the only manifestation of the syndrome. In one patient, a malignant islet-cell tumor was found at autopsy. Because multiple pancreatic cysts did not cause major clinical symptoms and because follow-up examinations over an average period of 5 years did not show significant progression of the lesions, it is concluded that these patients usually do not require surgical treatment. Abdominal ultrasound screening is recommended for patients at risk as a tool to identify potential von Hippel-Lindau syndrome gene carriers with pancreatic manifestations. In all patients with multiple pancreatic cysts, the von Hippel-Lindau syndrome should be included in the differential diagnosis.

Fibronectin Concentration in Ascites Differentiates Between Malignant and Nonmalignant Ascites

Differentiation between malignant and nonmalignant ascites by means of laboratory parameters has so far not been completely achieved. One hundred and four patients with ascites (34 malignant, 51 cirrhotic, and 19 other) were studied for fibronectin concentration in ascites. The first 47 patients (13 malignant and 34 cirrhotic) were used to determine mean values and standard deviation (178 +/- 96 vs. 8.3 +/- 15.3 micrograms/ml) and to define a cutoff concentration between both groups (75 micrograms/ml). Several other parameters were analyzed simultaneously in these patients (total protein: 3.93 +/- 1.46 vs. 1.50 +/- 1.02 g/dl; white cell count: 2022 +/- 1153 vs. 569 +/- 405/mm3; lactic acid: 3.86 +/- 2.57 vs. 1.83 +/- 0.72 mmol/L; lactic acid dehydrogenase: 357 +/- 329 vs. 61 +/- 35 U/L; serum/ascites ratio of lactic acid dehydrogenase: 1.11 +/- 1.13 vs. 4.06 +/- 2.00; pH: 7.275 +/- 0.229 vs. 7.513 +/- 0.042). Their accuracy (mean of sensitivity and specificity) was always less than 87% due to a considerable overlap between both groups. Five patients with other causes of ascites could not be classified at all. Application of fibronectin determination on the subsequent 57 patients (21 malignant, 17 cirrhotic, and 19 other) revealed a sensitivity, specificity, and negative and positive accuracy for malignant ascites of 100%. Calculation of these parameters for all 104 patients gave identical values. The inclusion of 3 patients without final diagnosis in the group of nonmalignant ascites reduced specificity to 97.1 and positive accuracy to 94.4%. However, these values were superior to all other methods used so far. Fibronectin determination in ascites in combination with other parameters suitable for exclusion of infectious or pancreatic origin of ascites may prove useful in the differential diagnosis of ascites.

Identification of the 110 000 Mr glycoprotein isolated from rat liver plasma membrane as dipeptidylaminopeptidase IV

We have described a dissociated turnover of terminal carbohydrates and protein component of a 110 000 M, glycoprotein isolated from rat liver plasma membrane: fucose, N-acetylneuraminic acid and galactose turn over several times on the intact polypeptide [l], whereas mannose and Nacetylglucosamine (core sugars in N-glycosidically bound carbohydrate chains) turn over coordinatedly to the protein [2]. Here, we describe the identification of the isolated glycoprotein as the monomer of dipeptidylaminopeptidase IV (EC 3.4.14.X) a dimeric glycoprotein of the plasma membrane. Our results suggest differently glycosylated forms of this enzyme within the cell. photometer. Alternatively, the following method was used (modified according to [4]): 0.05 ml glycyl-prolyl-p-nitroanilide tosylate solution (10 mg/ml H20), 0.005-o. 1 ml enzyme-containing solution, add 1.0 ml with 0.1 mol/l Tris buffer (pH 8.0). E was measured at 405 nm using a Gilford UV/VIS photometer. For routine measurements the latter method was taken. Protein was determined as in [5]. Rat liver plasma membranes were isolated by the method in [6] with some modifications [7] and checked for purity as described. Fractionation of plasma membrane glycoproteins and isolation of the 110 000 Mr glycoprotein were performed as in [l]. SDS gel electrophoresis was performed as in [8].

Urea‐Cycle Enzymes in Normal Liver and in Patients with Alcoholic Hepatitis

Abstract Urea‐cycle enzymes and omithine‐ketoacid‐transaminase have been measured in biopsy specimens of liver from healthy subjects and from patients suffering from alcoholic hepatitis. Both groups of subjects received a hospital diet of about 100 g of protein daily. Extraction of enzymes from biopsy specimens was performed by a standardized technique.–The DNA content of liver did not vary significantly between the groups, whereas protein content was significantly lower in patients with alcoholic hepatitis than in controls (p < 0.05). Of the enzymes tested, the activities of carbamyl‐phosphate synthetase and arginase were significantly decreased (p < 0.05 and p < 0.005 respectively) in patients with alcoholic hepatitis. Activities of arginosnccinate lyase, ornithine‐ ketoacid‐transaminase and ornithine‐carbamylphosphate transaminase remained unchanged in both groups.–These results demonstrate that alterations in arginase and carbamylphoa‐phate synthetase‐activities in the liver of patients with alcoholic hepatitis precede the histological manifestation of liver cirrhosis, which is associated with a significant decrease in some urea cycle enzymes [3, 15, 16]. Therefore the determination of arginase and carbamylphosphate synthetase in needle‐biopsies of human liver represent sensitive parameters of liver cell necrosis during the course of alcoholic hepatitis.

Phenotypic and immunoregulatory analysis of intestinal T‐cells in patients with inflammatory bowel disease: evaluation of an in vitro model

Abstract. Although a disturbed immune response to constituents of the gut mucosa has been implicated in the pathogenesis of inflammatory bowel disease, the mechanisms are still unclear. Intestinal T‐cells derived from gut biopsies were propagated in vitro as single and co‐cultures under different experimental conditions prior to flow cytometry. Intestinal T‐cell lines from inflamed mucosa (n= 69) showed a significant (P < 0.001) decrease in CD4+ T‐cells compared to T‐cells from normal (n= 49) and uninflamed (n= 29) tissue specimens. Co‐culturing of inflamed and uninflamed mucosa led to a normalization of CD4+ T‐cells in cultures derived from inflamed mucosa. Analysis of supernatants revealed a significantly (P< 0.001) increased secretion of IL‐ 4 under co‐culture conditions. Moreover, stimulation of cultures derived from inflamed mucosa with rIL‐4 led to a significant (P< 0.001) increase in CD4+ T‐cells, whereas anti‐IL‐4 antibodies or IFN‐γ supplementation of T‐cells derived from uninflamed mucosa significantly (P < 0.001) reduced the CD4+ subset. Treatment with IFN‐γ and anti‐IL‐4 antibodies did not affect the phenotype of T‐cells derived from inflamed mucosa. These data suggest that IL‐4 might play a key role in the intestinal immune response. Furthermore, this in vitro system allows the investigation of mucosal immune mechanisms in more detail under standardized conditions.

Exploring the genetic role of the HLA-DPB1 locus in Chileans with intrahepatic cholestasis of pregnancy

BACKGROUND/AIMS Intrahepatic cholestasis of pregnancy is a rare disease of unknown etiology, with a strikingly higher prevalence in Chile than in most other countries. Although several studies suggest that a genetic predisposition is involved in the pathogenesis, no genetic disease-marker has so far been identified. Using a recently developed HLA-genotyping technique, we performed an association study with a highly polymorphic HLA class II gene in patients with recurrent intrahepatic cholestasis of pregnancy and normal control patients. METHODS Genomic DNA was extracted from 26 unrelated patients with recurrent ICP and 30 unrelated multiparous women without a personal or family history of this disease among a Chilean population. The polymorphic second exon of the HLA-DPB1 gene was amplified by the polymerase chain reaction and hybridized with 25 sequence-specific oligonucleotide probes to assign the HLA-DPB1 alleles on the basis of known sequence variations. RESULTS Out of more than 50 HLA-DPB1 alleles presently known, 13 were represented in the analyzed groups. Patients with ICP had a higher frequency of the allele DPB*0402 when compared to controls (69% vs 43%). This difference failed to reach statistical significance (x2 = 2.81, corrected p > 0.5). No significant differences were observed between the frequencies of other detected HLA-DPB1 alleles in the analyzed groups. CONCLUSION In this study, we observed a high frequency of the allele HLA-DPB1*0402 among Chilean patients with recurrent ICP, but no association of the disease with HLA-DPB1 alleles. Therefore, HLA-DPB1 alleles do not play a major role in determining susceptibility or resistance to intrahepatic cholestasis of pregnancy.

Proteases and antiproteases related to the coagulation system in plasma and ascites: Prediction of coagulation disorder in ascites retransfusion

To improve the ability to predict the occurrence of coagulation disorders in ascites retransfusion and, in addition, to better define the nature of the coagulation disorder, several proteases and antiproteases were analyzed in ascites and plasma before ascites retransfusion in 17 patients. Plasminogen, alpha 2-antiplasmin, antithrombin III, and fibrin(ogen) degradation products in ascites were significantly altered in patients who later developed abnormal coagulation as compared to those who did not. Only plasminogen and alpha 2-antiplasmin in ascites achieved a sufficient predictive value for the occurrence of coagulation abnormalities. The pattern of the coagulation abnormalities observed strongly suggests fibrinolysis induced by the infusion of plasminogen activators as the cause of the coagulation disorder in ascites retransfusion procedures.

The lectin properties of gluten as the basis of the pathomechanism of gluten-sensitive enteropathy.

SummaryThe pathogenesis of gluten-sensitive enteropathy is as yet unknown. According to one theory gluten may act as a lectin with toxic properties for the intestinal cells.We can now confirm this theory by laser nephelometric measurements and demonstrate the oligomannosyl specificity of this lectin-like protein gluten. Furthermore, we demonstrate the highly more intensive binding capacity of gluten for the glycoproteins of the immature crypt cells of the intestinal brush border compared to those from the mature villous zone. It is discussed that gluten-sensitive enteropathy is caused by a genetically determined defect-glycosylation of intestinal glycoproteins with the synthesis of more mannosylated glycoproteins.

T-cell receptor variable genes and genetic susceptibility to celiac disease: An association and linkage study

BACKGROUND Genetic susceptibility of celiac disease is primarily associated with a particular combination of and HLA-DQA1/DQB1 gene; however, this does not fully account for the genetic predisposition. Therefore, the aim of this study was to examine whether T-cell receptor (TCR) genes may be susceptibility genes in celiac disease. METHODS HLA class II typing was performed by polymerase chain reaction amplification in combination with sequence-specific oligonucleotide hybridization. TCR alpha (TCRA), TCR gamma (TCRG), and TCR beta (TCRB) loci were investigated by restriction fragment length polymorphism analysis. RESULTS Allelic frequencies of TCRA, TCRG, and TCRB variable genes were compared between patients with celiac disease (n = 53) and control patients (n = 67), and relative risk (RR) estimates were calculated. The RR was 1.67 for allele C1 at TCRA1, 3.35 for allele D2 at TCRA2, 1.66 for allele B2 at TCRG, and 1.35 for allele B at TCRB, showing no significant association. Additionally, linkage analysis was performed in 23 families. The logarithm of odd scores for celiac disease vs. the TCR variable genes at TCRA, TCRG, and TCRB showed no significant linkage. CONCLUSIONS These data suggest that the analyzed TCR variable gene segments V alpha 1.2, V gamma 11, and V beta 8 do not play a major role in susceptibility to celiac disease.

Heterogeneous turnover of terminal and core sugars within the carbohydrate chain of dipeptidylaminopeptidase IV isolated from rat liver plasma membrane

Dipeptidylaminopeptidase IV, a plasma membrane‐bound glycoprotein, is characterized by an intramolecular hetereneous turover of the protein backbone and carbohydrate chain. The faster turnover of the latter is restricted only to the outer sugars. The inner core sugars D‐mannose and N‐acetyl‐D‐glucosamine turn over at the same rate as the protein backbone