A VAMP-binding protein from Aplysia required for neurotransmitter release

Before the fusion of synaptic vesicles with the plasma membrane, a protein complex is thought to form between VAMP--an integral membrane protein of the vesicle--and two proteins associated with the plasma membrane, SNAP-25 and syntaxin. The yeast two-hybrid interaction cloning system has now been used to identify additional proteins from Aplysia that interact directly with VAMP. A 33-kilodalton membrane protein, termed VAP-33 (VAMP-associated protein of 33 kilodaltons), was identified whose corresponding messenger RNA was detected only in the central nervous system and the gill of Aplysia. Presynaptic injection of antibodies specific for VAP-33 inhibited synaptic transmission, which suggests that VAP-33 is required for the exocytosis of neurotransmitter.

Low frequency of CDKN2 mutation in endometrial carcinomas

The CDKN2 gene on chromosome 9p21 encodes the p16 inhibitor of cyclin D/cyclin-dependent kinase 4 complexes. Mutations and deletions of CDKN2 have been frequently identified in cell lines, whereas most primary tumors have demonstrated a lower frequency of alteration. To assess the role of CDKN2 in endometrial tumorigenesis, 34 tumor samples were examined for loss of heterozygosity at 9p21 and mutation in CDKN2. To identify tumors that had lost 9p21, samples were genotyped with markers flanking the CDKN2 locus. The frequency of CDKN2 mutation in endometrial carcinomas was determined by single-strand conformation variant analysis and direct sequencing of variants. Of the 34 tumors examined, three revealed loss of 9p21 sequences. Two samples were characterized by point mutations in CDKN2, one of which also showed loss of 9p21 sequences.

Clinical and surgical aspects of double adenoma in patients with primary hyperparathyroidism

The incidence of double parathyroid adenoma in 277 prospectively documented patients suffering from primary hyperparathyroidism was 5.4 per cent (15 patients). Patients with double adenoma were all symptomatic and had a significantly higher parathyroid hormone (PTH) level and tumour weight than those with a solitary adenoma or four-gland hyperplasia. In 11 patients the adenomas were located bilaterally. Bilateral neck exploration must be performed routinely to deal successfully with this condition at initial operation. In six patients one enlarged gland was found in the thymus or posterior mediastinum. These locations should be explored, especially in patients with high PTH levels, in those in whom all four parathyroid glands cannot be detected or if only one small adenoma is found. In all such patients, selective resection of the enlarged parathyroid glands resulted in normocalcaemia (median follow-up 3.5 years). Selective resection of the pathological glands is the treatment of choice.

CD15 and HKN-1 reveal cerebellar compartments with a complex overlap

The CD15-epitope in the cerebellar cortex is expressed by Bergmann glial fibers which are organized in symmetrical iterative stripes. Their arrangement appears complementary to the pattern described for the organization of compartments demonstrated by any other marker used so far. HNK-1 however, reveals stripes that are not complementary to the general pattern for the organization of compartments.

Characterization of a Y-Box factor from Aplysia californica

A cDNA isolated from the marine invertebrate Aplysia californica encodes a protein containing a domain with a high degree of homology to the Y-Box-binding factors. The expression of this gene is unaffected by the facilitatory neurotransmitter, 5-hydroxytryptamine. When expressed in Escherichia coli, the encoded protein is shown to bind RNA in vitro.

[Pancreatitis in primary hyperparathyroidism (pHPT) is a complication of advanced pHPT]

Pancreatitis occurred in 13 (5.6%) of 234 patients (76 men, 158 women; mean age 63 [2-83] years) who were operated on for primary hyperparathyroidism (pHPT) between 1987 and 1992. The pancreatitis patients had a significantly higher median level of parathormone (340 pg/ml), of serum calcium (3.2 mmol/l) and of thyroid weight (1.7 g) than the remaining 221 patients (135 pg/ml; 2.9 mmol/l; 1.0 g, respectively: P < 0.05 for each). In ten patients pHPT had been diagnosed during an attack of pancreatitis: pancreatitis had been the diagnostic clue to pHPT. After conservative treatment of the pancreatitis and parathyroidectomy seven of the ten patients were free of symptoms during the follow-up. In one patient pancreatitis recurred postoperatively and two patients died of the consequences of haemorrhagic necrotizing pancreatitis. Cholelithiasis, as another possible causative factor for pancreatitis, was present in five of the 13 patients (38%). None of the patients was an alcoholic. These data indicate that there is a positive correlation between advanced pHPT and pancreatitis. Pancreatitis may be the expression of much advanced hyperparathyroidism which has been diagnosed too late.

[Laparoscopic cholecystectomy in morbid obesity. Indications or contraindications?]

In early reports on the experience with laparoscopic cholecystectomy severe obesity was considered a contraindication for this procedure. The prospectively documented data of 370 consecutive patients undergoing laparoscopic cholecystectomy were analysed to investigate, whether this point of view is still justified. 35 of these 370 patients were classified as being severely obese (body-mass-index greater than 33 kg/m2). Median operation time was significantly longer in these patients than in the remaining patients (p < 0.05). In selected cases the operative technique had to be slightly modified due to extreme abdominal wall thickness. Dissection of Calot's triangle was not more difficult than in non-obese patients. There was no statistically significant difference concerning conversion rates between severely obese patients (11.4%) and the other group of patients (15.5%). Also, the number of complications was not increased in the obese patients. Since the higher complication rate in severely obese patients after conventional abdominal surgery is mainly due to the incision, laparoscopic cholecystectomy is the preferable procedure to treat symptomatic gallstone disease in these patients.

[Laparoscopic adrenalectomy]

Between June and September 1993, laparoscopic adrenalectomy was indicated in five patients (three women, two men; aged 25-50 years). Three had a phaeochromocytoma, two had an adenoma (Conn's syndrome). Four of the five tumours were localized to the right adrenal gland, one to the left. Tumour diameter ranged from 3 to 5 cm. The laparoscopic procedure was successful in four of the patients (three right, one left). In the fifth case the operations had to be completed by conventional surgery, because of non-controllable haemorrhage. Duration of operation ranged between 165 and 360 min for right adrenalectomy and was 135 min for the left one. Rapid convalescence, lower dose of pain-killing drug required, short hospital stay and good cosmetic results characterized the postoperative course after the laparoscopic procedure. This technique thus opens up new perspectives for adrenal surgery.

[Broad use of laparoscopic cholecystectomy in the teaching clinic. Experiences and results of 300 operations]

Laparoscopic cholecystectomy (LC) was integrated early in surgical training according to the concept "observe, assist and then operate under the assistance of an experienced surgeon". 300 LC's were performed by 27 different surgeons (8 board certified surgeons, 19 residents in the year 2-6 of training). 60.3% of all LC's and 73% of LC's performed for acute cholecystitis were done by residents. Our results including an overall complication rate of 5.3% shows, that LC can be performed by residents without additional complications or unacceptable length of operations, provided the threshold for conversion is low and the surgeon is assisted by an experienced laparoscopist. We therefore suggest that the early integration of LC in surgical training is justified.

[Parathyroid gland cancer. Problems in diagnosis and therapy]

Parathyroid carcinoma occurs in 0.1 to 5% as the cause of primary hyperparathyroidism (HPT). It is difficult to determine the true incidence, because parathyroid carcinoma is diagnosed too often due to unreliable histologic criteria. It is only justified to make the diagnosis, when a local recurrence or metastases with the clinical picture of a recurrent or persistent HPT occurred. Treatment of choice is the initial en-bloc resection, which may result in long disease-free intervals. Pharmacological treatment, chemotherapy, and radiation are mostly ineffective in the treatment of parathyroid carcinoma. A satisfactory long-term palliation can only be achieved with repeated resections of the local recurrences and metastases. Diagnostic efforts should be made to localize the recurrent tumor before every reoperation, whereby ultrasonography of the neck is the most sensitive procedure. Occasionally the parathyroid tissue cannot be identified in spite of preoperative diagnostic studies or hypercalcemia persists after surgery. In these cases forced diuresis and medical treatment with calcitonin, diphosphonates or mithramycine can briefly control hypercalcemia. The clinical courses of 3 patients with metastasizing parathyroid carcinoma are presented and discussed. In these patients 3 to 11 surgical interventions were performed in combination with an intermittent medical treatment. By this regimen we achieved long-term palliations up to 13 years.

Retinoic acid-mediated repression of human papillomavirus 18 transcription and different ligand regulation of the retinoic acid receptor beta gene in non-tumorigenic and tumorigenic HeLa hybrid cells

Human papillomavirus type 18 (HPV18) belongs to the group of genital papillomaviruses involved in the development of cervical carcinomas. Since retinoic acid (RA) is a key regulator of epithelial cell differentiation and a growth inhibitor in vitro of HPV18-positive HeLa cervical carcinoma cells, we have used HeLa and HeLa hybrid cells in order to analyse the effects of RA on expression of the HPV18 E6 and E7 oncogenes and of the cellular RA receptor genes RAR-beta and -gamma. We show here that RA down-regulates HPV18 mRNA levels apparently due to transcriptional repression. Transient cotransfection assays indicated that RARs negatively regulate the HPV18 upstream regulatory region and that the central enhancer can confer RA-dependent repression on a heterologous promoter. RA treatment resulted in induction of RAR-beta mRNA levels in non-tumorigenic HeLa hybrid cells, but not in tumorigenic hybrid segregants nor in HeLa cells. No alterations of the RAR-beta gene or of the HeLa RAR-beta promoter could be revealed by Southern and DNA sequence analysis, respectively. As determined by transient transfection assays, however, the RAR-beta control region was activated by RA more strongly in non-tumorigenic hybrid cells than in HeLa cells, thus indicating differences in trans-acting regulatory factors. Our data suggest that the RARs are potential negative regulators of HPV18 E6 and E7 gene expression, and that dysregulation of the RAR-beta gene either causatively contributes to or is an indicator of tumorigenicity in HeLa and HeLa hybrid cells.

Human papillomavirus type 18 E6*, E6, and E7 protein synthesis in cell-free translation systems and comparison of E6 and E7 in vitro translation products to proteins immunoprecipitated from human epithelial cells

Expression of the E6 and E7 transforming genes of human papillomavirus type 18 (HPV18) occurs via structurally bicistronic mRNAs in which the downstream open reading frame (ORF) E7 is preceded either by the full-length ORF E6 or by a spliced ORF, E6*. We have used in vitro transcription and translation of HPV18 cDNAs in order to analyze the synthesis of E6*, E6, and E7 proteins and to compare the E6 and E7 in vitro translation products with the authentic proteins immunoprecipitated from cervical cancer cells. In wheat germ extract, in vitro translation resulted in the production of all three proteins, E6*, E6, and E7. In rabbit reticulocyte lysate, however, only the E6 and E7 proteins were produced. The lack of E6* protein was due neither to template RNA degradation nor to an inhibitory influence of the RNA 5' leader sequences, thus indicating the possibility of either inhibition of synthesis or degradation of E6* protein in reticulocyte lysate. The E7 protein was synthesized from both E6*-E7 and E6-E7 RNAs. In vitro-synthesized and authentic HPV18 E7 proteins revealed identical electrophoretic mobilities in two-dimensional gel electrophoresis, thus indicating similar modifications. By using a monoclonal antibody against the N terminus of HPV18 E6* and E6, an 18-kDa protein was detected not only in HPV18-positive but also in HPV18-negative epithelial cells. The 18-kDa proteins and the in vitro-synthesized HPV18 E6 protein exhibited comparable electrophoretic characteristics in two-dimensional gels. These results suggest the possible existence of a cellular protein related to HPV18 E6.

Influence of chromosomal integration on glucocorticoid-regulated transcription of growth-stimulating papillomavirus genes E6 and E7 in cervical carcinoma cells

In most cervical carcinoma cells the E6 and E7 genes of specific human papillomaviruses are transcribed from viral sequences integrated into host cell chromosomes. Glucocorticoids activate the promoter elements of various human papillomaviruses in transient-expression assays. We have analyzed the effect of dexamethasone on the transcription rate of human papillomavirus 18 E6 and E7 genes integrated at different chromosomal sites in four cervical cancer cell lines. Dexamethasone led to an increase in the transcription rate of the integrated E6-E7 sequences in C4-1 and C4-2 cells but led to a decrease in SW 756 cells and did not affect the transcription rate in HeLa cells. However, when the viral promoter elements derived from HeLa or SW 756 cells, in which dexamethasone does not activate transcription of the integrated E6-E7 sequences, were tested in transient-expression assays within the same cell lines, dexamethasone consistently activated the viral promoter. It thus appears that dominant regulatory mechanisms presumably depending on the chromosomal integration site are able to override the response of the viral promoter to steroid hormones. The growth rate of all dexamethasone-treated cell lines correlated consistently with the expression of the papillomavirus E6 and E7 genes, supporting their role in the maintenance of the proliferative phenotype of cervical carcinoma cells. Since human papillomaviruses are integrated into the host cell genome at variable, presumably randomly selected chromosomal loci, regulatory mechanisms that influence viral gene expression, and hence cell growth, may differ among cancers of independent clonal origin.

Distribution of the 3-fucosyl-N-acetyl-lactosamine (FAL) epitope in the adult mouse brain

The distribution of the 3-fucosyl-N-acetyl-lactosamine (FAL) epitope within the adult mouse brain was studied by immunohistochemistry using the monoclonal antibody Leu-M1. Leu-M1-positive elements comprised astrocytes and neurons. FAL-positive astrocytes were particularly abundant in barrier structures of the brain, but were also prominent at the periphery of most medullated fiber tracts. Their intracerebral distribution led to a distinct pattern of organization, which in some locations, including the cerebral cortex, could be used for an extended regional architectonic description. Since only some FAL-positive astrocytes were also positive for glial fibrillary acid protein (GFAP), the emerging topography of the FAL-positive astrocytes often differed from the GFAP-distribution. In the cerebellum, Bergmann glia cells expressed the FAL epitope and, in the vermis, their arrangement had a band-like appearance. Positive oligodendrocytes could not be identified. The common ependymal cells were negative, whereas tanycytes were highly immunoreactive. The Leu-M1 antibody also stained some neurons. These occurred in selected neocortical regions, within the dorsal and ventral striatum, in the globus pallidus, the nucleus basalis of Meynert, the nucleus diagonalis and some hypothalamic areas. In some instances, their morphology and location indicated an association with neurochemically specified cell groups.

Suppression in vivo of human papillomavirus type 18 E6-E7 gene expression in nontumorigenic HeLa X fibroblast hybrid cells

The E6 and E7 genes of the cancer-associated human papillomavirus (HPV) types 16 (HPV16) and 18 (HPV18) can induce cell immortalization in vitro in normal human keratinocytes. This, however, is not associated with tumorigenicity in vivo. On the other hand, tumorigenicity of HPV18-positive HeLa cervical carcinoma cells can be suppressed by fusion of HeLa cells with normal human keratinocytes or fibroblasts. We have addressed the question of whether suppression of tumorigenicity in HeLa x fibroblast hybrid cells might be due to a reduced ability of these cells to express the HPV18 E6-E7 genes in vivo. Nontumorigenic hybrid cells and tumorigenic hybrid segregants were transplanted as organotypical cultures or injected subcutaneously into immunocompromised mice and were analyzed for HPV18 E6-E7 gene expression by RNA-RNA in situ hybridization. The tumorigenic hybrid cells showed a continuous and invasive growth that was associated with high levels of HPV18 E6-E7 mRNAs at all time points examined. In contrast, the nontumorigenic hybrid cells stopped cell proliferation approximately 3 days after transplantation. At this time they expressed the E6-E7 genes at low levels, whereas at day 2 high expression levels were observed. However, the mRNA levels of the cytoskeletal genes beta-actin and vimentin remained high for at least 14 days, demonstrating that inhibition of growth and of HPV18 E6-E7 gene expression was not due to cell death. These results suggest that growth inhibition of the nontumorigenic HeLa x fibroblast hybrid cells in vivo might be caused by suppression of HPV18 E6-E7 gene expression and are compatible with the idea of an intracellular surveillance mechanism for HPV gene expression existing in nontumorigenic cells.

Epstein-Barr virus nuclear antigen type 1 binding: electron microscopy

Epstein-Barr virus (EBV) nuclear antigen type-1 (EBNA-1) was extracted and purified from Raji cells by chromatography on DNA-Sepharose and Blue-dextran Sepharose. Its complexes with plasmid pM765-10 derived from EBV (strain M-ABA) DNA were visualized by electron microscopy. The criteria of specificity were as follows: (1) preferential binding of EBNA-1 to the ori-P region of pM765-10; (2) specific enlargement of EBV DNA/EBNA-1 complexes with anti-EBNA-1 (IR-3) IgG antibody; and (3) resistance of the resulting EBV DNA/EBNA-1/anti-EBNA-1 antibody complexes to treatment with 1.5 M NaCl. The optimal conditions for the formation of EBV DNA/EBNA-1 complexes were 50 to 150 mM NaCl and pH 6.0. A balanced equilibrium of EBNA-1 and pM765-10 was necessary to achieve both a high yield and specificity of EBV DNA/EBNA-1 complexes.

Electron microscopy of binding of Epstein-Barr virus (EBV) nuclear antigen (EBNA-1) to EBV DNA

Specific binding sites for Epstein-Barr virus (EBV) nuclear antigen (EBNA-1), isolated and semipurified from EBV-transformed nonproductive Raji cells, were visualized on the molecule of EBV DNA by electron microscopy and mapped. Two measures had to be applied to counteract the limited purity of the EBNA-1 preparation: (i) EBV DNA/EBNA-1 complexes were specifically enlarged by binding with anti-EBNA-1 (IR-3) IgG antibody. (ii) DNA-binding proteins that did not react with the anti-EBNA-1 antibody were eluted from EBV DNA with 1.5 M NaCl, taking advantage of the resistance of DNA/EBNA-1/anti-EBNA-1 antibody complexes to the high-salt treatment. EBNA-1 bound at the highest relative frequency (greater than 30%) to the EBV DNA map positions of 8.8 +/- 0.3, 10.3 +/- 0.5, and 46.6 +/- 1.2 kb. It bound with a lower but still statistically significant frequency (16%) to the map positions of 64.5 +/- 1.0, 89.7 +/- 1.6, 129.6 +/- 1.1 kb.

Transfection of human lymphocytes with cloned Epstein-Barr virus (EBV) DNA

Human primary cord-blood lymphocytes were transfected, using the DEAE-dextran technique, with a set of seven largely overlapping clones jointly covering the whole M-ABA Epstein-Barr virus (EBV) genome. Three fragments, cosmids cMB-14 and cM301-99 and plasmid pM966-20, were able to stimulate transient cellular DNA synthesis, blastic transformation, and clumps formation, as well as to prolong the life span from a maximum of 2 weeks in control cultures to up to 6 weeks. The fragments stimulating DNA synthesis also expressed this property in mutual combinations or when combined with cosmid cMSal-A or cM302-21. Their use with any other fragments in cotransfection did not result in further DNA synthesis stimulation. Cosmids cM302-23 and cMSal-B suppressed this effect. Cosmid cM301-99 but not cM302-23 induced transient EBNA-1 formation in about 1% of lymphocytes. Lymphocytes transfected with single fragments or their combinations failed to grow into immortalized cell lines. The results suggest that transient expression of viral functions at levels achievable by transfection is not sufficient for cell immortalization.

[Experimental development of hollow cellulose membranes for blood detoxification]

In recent years there have been repeated demands in medical circles for new membranes for various purposes. At present attention is focussed on the development of membranes for the detoxification of blood. Using available technology and resources, it seemed appropriate to develop such hollow membranes out of cellulose by the viscose process. It is possible to give the membrane a suitable structure according to the use intended. The transport of matter and ultrafiltration can be influenced by varying the influence parameter in the spinning process via changes in the pore structure. In this way it is possible to produce hollow membranes for dialysis or ultrafiltration, with varying grades of permeability, out of cellulose by the viscose process.