Gene Literature Dashboard

A group of 241 nonpretreated breast carcinomas was studied for estrogen receptor (ER) and progesterone receptor (PR) content by both immunocytochemistry (ICC) and biochemical analysis (dextran-coated charcoal [DCC]). While the tumors were judged to be ER positive in 67.6% and PR positive in 65.6% by ICC, DCC analysis showed positive results in 77.6% for both ER and PR. There was only a moderate correlation between the semiquantitative results of ER and PR ICC and the corresponding values for DCC receptor determination. Among tumors shown to be steroid receptor positive by ICC, a majority showed a wide spectrum of staining intensity, from negative to intensely positive (type C staining pattern, ER 87.7%, PR 73.4%). Less frequently, carcinomas showing uniform, intense staining of all epithelial tumor cells were observed (type A staining pattern, ER 11.7%, PR 18.4%). Finally, only very few tumors had both clearly negative and distinctly positive cells (type B staining pattern, ER 0.6%, PR 8.2%). On analyzing the relationship between the expression of steroid receptors (ICC and DCC) and the prognostic factors axillary node status, tumor size, tumor histology, grade and patient age, only a significant correlation between patient age and ER (ICC, r = .46; DCC, r = .43), a weakly significant negative correlation between node involvement and ER, and a weakly significant negative correlation between tumor grade and ER (ICC only) as well as between tumor grade and PR were found. Among all patients, the recurrence-free interval was significantly longer in patients with ER- or PR-positive carcinomas (ICC and DCC).(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of histones in Escherichia coli is important in structural studies on chromatin, because it allows isotopic labeling such as deuteration and replacement of methionines with selenomethionine as well as expression of specific domains of histones. We show that full-length H5 cannot be expressed in E. coli. We have determined that the problem is translational rather than transcriptional. Pulse-labeling studies show that protein turnover is not the reason for lack of accumulation. On dissecting the gene, we find that the problem lies in expressing the highly charged C-terminal tail of H5. We can make progressively increasing amounts of the tail, but at the point where over two-thirds of this region is transcribed, the protein ceases to be made. Surprisingly, full-length H1 is made. In vitro studies show that the H5 gene can be translated in a rabbit reticulocyte system but not in an E. coli system, suggesting that there may be a difference in the ability of eukaryotic and prokaryotic ribosomes to translate this message. The expression of the globular domains of H5 and H1 posed a different problem. There was little or no expression of some of the constructs, even though they were fragments of larger constructs that were well made. Replacement of the first five codons downstream of the initiating ATG codon with those optimized for E. coli, and which were AT rich, restored expression. This may have general implications for expression of eukaryotic proteins in E. coli.

Antiprogestins form a new potential treatment modality for breast cancer and their mode of action has been assessed in vitro on several breast cancer cell lines, in vivo in rats with dimethylbenzanthracene (DMBA)-induced mammary tumours and in vivo in patients with metastatic breast cancer. In vitro in serum-free medium, the progestin Org 2058 and antiprogestins RU486 and Org 31710 caused a dose-dependently stimulated MCF7 cell growth. Both antiprogestins dose-dependently inhibited the oestrogen-stimulated proliferation of progesterone receptor (PgR)-rich T-47D cells in DCC medium. Inhibition by Org 31710 plateaued at 10(-8) M (74% inhibition), compared with RU486 at up to 10(-6) M (53% inhibition). No inhibition was observed at doses of 10(-12)-10(-6) M of both antiprogestins in the absence of oestradiol. The proliferation of the ZR-75.1 and MDA-MB-231 cell lines was not or only marginally affected by either antiprogestin. Rats with DMBA-induced mammary tumours given prophylactic treatment with RU486 displayed a doubled latency period. Antiprogestins were slightly more effective than tamoxifen or progestins in rats with existing tumours. Org 31710 sometimes showed a somewhat more pronounced inhibitory effect than the antiprogestins Org 31806 and RU486. Combined antiprogestational and anti-oestrogenic treatment showed striking additive growth inhibitory effects resulting in clear tumour remissions, in the presence of very strong suppression of oestrogen and PgRs. The growth inhibitory effect of luteinizing hormone-releasing hormone agonists was potentiated by antiprogestins.(ABSTRACT TRUNCATED AT 250 WORDS)

1. The metabolism of 1,1,2,2-tetrafluoro-1-(2,2,2-trifluoroethoxy)-ethane (HFE), a prospective chlorofluorocarbon alternative, was studied in rat and human liver microsomes and in rat in vivo. 2. HFE was metabolized to inorganic fluoride, trifluoroacetaldehyde hydrate, trifluoroacetic acid and difluoroacetic acid, which were identified by 19F-nmr in microsomal incubation. After i.p. dosing with 200 mg/kg HFE to rat, trifluoroacetic acid and trifluoroacetaldehyde hydrate were identified as urinary metabolites. 3. The formation of inorganic fluoride from HFE was used to quantify oxidative metabolism. In liver microsomes from untreated rat, formation of inorganic fluoride could not be detected. However, microsomes from rats treated with P4502E1 (2E1) inducers ethanol and pyridine catalysed the formation of fluoride at different rates. The extent of fluoride formation in microsomes correlated with the amount of 2E1 protein as determined by immunoblots with a polyclonal antibody and with the extent of oxidation of p-nitrophenol and chlorzoxazone, two specific substrates for 2E1. 4. In different samples of human liver microsomes, the formation of inorganic fluoride correlated well with the ability of the microsomes to oxidize chlorzoxazone and p-nitrophenol and the amount of 2E1 protein as determined by immunoblots. 5. The obtained results suggest that 2E1 plays a major role in the metabolism of HFE in rat and man.

In order to evaluate the drugs in treating endometriosis, the direct effects of gossypol acetate, danazol, progesterone, and gonadotropin releasing hormone-agonist (GnRH-A) on the isolated human endometrial cells were determined by DCC assay. The binding capacity of cytosolic estradiol receptor (E2R) and progesterone receptor (PR) in groups treated with gossypol acetate or progesterone decreased. In danazol-treated group, the binding capacity of PR decreased but not that of E2R. GnRH-A showed no significant effect on the binding capacity of E2R and PR. There was a significant linear correlation between the inhibitory rates of PR binding capacity of progesterone and danazol. The results suggested that gossypol acetate, danazol and progesterone might have peripheral effects mediated by steroid receptors, while GnRH-A work clinically through the central path way only.

Modified analogues of antisense oligodeoxynucleotides (ODNs), particularly phosphorothioates ([S]ODNs), have been extensively used to inhibit gene expression. The potential sequence specificity of antisense oligomers makes them attractive as molecular drugs for human diseases. The use of antisense [S]ODNs to inhibit gene expression has been complicated by frequent nonspecific effects. In this study we show in diverse cell types that [S]ODNs, independent of their base sequence, mediated the induction of an Sp1 nuclear transcription factor. The [S]ODN-mediated Sp1 induction was rapid and was associated with elevated levels of Sp1 protein. This induction was dependent on NF-kappa B activity, since inhibition of NF-kappa B activity abolished the [S]ODN-induced Sp1 activity. [S]ODN-induced Sp1 activity was seen in mouse spleen cells following in vivo administration. Sp1 activity induced by [S]ODNs required the tyrosine kinase pathway and did not have transactivating potential. These results may help to explain some of the non-specific effects often seen with [S]ODNs.

A susceptibility to hereditary nonpolyposis colorectal cancer (HNPCC) was recently shown to be due to mutations in the MSH2 gene on chromosome 2p. A second susceptibility locus has been mapped to chromosome 3p in two families. The present report describes the results of a genetic study of Finnish HNPCC kindreds. Of 18 apparently unrelated families living in different parts of the country, 11 could be genealogically traced to a common ancestry dating at least 13 generations back in a small geographic area. Linkage studies were possible in 9 families, revealing conclusive or probable linkage to markers on 3p in 8. Five of these were among those having shared ancestry. The location of the gene was refined by a linkage study comprising 12 marker loci. By analysis of recombinations in such families, the HNPCC locus could be assigned to the 1-centimorgan interval between marker loci D3S1561 and D3S1298. A haplotype encompassing 10 centimorgans around the HNPCC locus was conserved in five of the pedigrees with shared ancestry and present in 2 further families in which linkage analysis was not possible. Our results suggest the presence of a widespread single ancestral founding mutation. Moreover, the map position of the 3p gene for HNPCC susceptibility was greatly refined.

<h4>Objective</h4>To determine the behaviour of the coagulation variables antithrombin III (ATIII), protein C, thrombin/antithrombin III (TATIII); fibrinolytic activity, tissue plasminogen activator antigen (t-PA), plasminogen activator inhibitors (PAI) 1 and 2, and endothelial involvement by fibronectin assay in normal and pre-eclamptic pregnancies.<h4>Design</h4>Longitudinal and cross-sectional observational study.<h4>Setting</h4>Antenatal clinic and maternity hospital.<h4>Subjects</h4>Thirty-six primigravid normotensive caucasian patients, four of whom subsequently developed pre-eclampsia, and 12 patients with established pre-eclampsia.<h4>Main outcome measures</h4>Plasma levels of PAI-1, PAI-2 and t-PA antigen were determined using an ELISA technique as were TATIII complex levels of fibronectin. ATIII and protein C plasma levels were assayed using chromogenic substrate techniques.<h4>Results</h4>PAI-1 and PAI-2 antigen levels rose progressively throughout normal pregnancy. Among the established pre-eclamptic group compared with matched normal pregnancies, the PAI-2 antigen level was significantly lower (48.5 +/- 22.8 versus 183.5 +/- 37.4; P < 0.001), the PAI-1 antigen level was significantly higher (122 +/- 34.4 versus 79.2 +/- 19.7; P < 0.001), ATIII activity was significantly lower (87.8 +/- 27.1 versus 110.9 +/- 19.3; P < 0.001) and TATIII complex levels were significantly higher (16.9 +/- 6.4 versus 10.2 +/- 5.9; P < 0.001). Among the four initially normotensive patients who subsequently developed pre-eclampsia, fibronectin levels were significantly elevated from as early as nine weeks of gestation.<h4>Conclusion</h4>Significantly elevated levels of PAI-1 and fibronectin occurring early in pregnancies that subsequently develop pre-eclampsia suggest that these variables may have predictive values. PAI-2 would seem to be a marker of placental function in pre-eclampsia while increased t-PA and TATIII complex levels reflect the severity of the condition.

The development of highly specific and sensitive monoclonal antibodies directed against human estrogen (ER) and progesterone receptors (PR) provides a new approach in precise histochemical receptor location independent of hormone binding. Over the years receptor determination was the domain of the radioligand-binding assay, in which receptors are measured by tritiated ligand and unbound ligand is removed by the dextran-coated charcoal (DCC) procedure. Presented here are the results and experiences obtained by the classic DCC and the immunocytochemical method in the different normal and tumorous tissues of the female reproductive tract and the breast. The results of both methods were compared, and overall concordance of the results was found to vary considerably among the different types of tissue analyzed. Best agreement (86%) was found for PR determination in breast cancer, and the lowest rate of concordance for ER determination in fibrocystic disease of the breast. Special attention was directed toward the heterogeneity of receptor distribution in the specimens examined. In all tissues investigated, ER and PR were located in the nuclei of cells in both paraffin and frozen sections. Staining intensity varied among different cell types and from cell to cell for a single cell type, as well as in tumorous and normal tissues. In breast cancer, randomly scattered single cell receptor positivity was distinguished from focal/clonal positivity. Paraffin-embedded lymph node metastases showed significantly weaker staining as compared with their respective primary tumors. In the normal ovary, the corpus luteum and the stromal layer of the outer cortex were revealed as highly receptive elements for progestins, whereas ER was barely demonstrable in the normal ovary. Benign serous and mucinous ovarian tumors showed opposite ER and PR distribution among the stromal and epithelial components. Of special interest were the highly significant changes in ER and PR content in the stromal and glandular cells of the different layers of the normal endometrium throughout the menstrual cycle.

Tumor suppressor genes APC and MCC were identified recently, and their chromosomal location was ascribed to chromosome 5q21. Mutations in the APC gene give rise to familial adenomatous polyposis and occur in many perhaps even the majority, of sporadic colon cancers. Loss of heterozygosity has been described in other human tumors such as lung and esophageal cancers. Here we show loss of heterozygosity (LOH) in 87 patients with breast cancer for the APC and/or MCC loci using a polymerase chain reaction-LOH assay. LOH affected loci in APC exons 11 and 15 in 9 of 35 (25%) and 4 of 34 (11%) heterozygous patients, respectively. LOH at the MCC exon 10 locus occurred in 7 of 40 (17%) informative samples. These data suggest that allelic deletion of APC and/or MCC is probably involved in the pathogenesis and/or progression of a subset of breast cancers.

An in vitro assay system for predicting the estradiol (E2) sensitivity of clinical cancer cells was applied to 54 patients with breast carcinoma to compare the responses to E2 and tamoxifen (TAM) with the estrogen receptor (ER) status. We found that 18 of the 35 cases in the ER-positive group and 6 of the 19 cases in the ER-negative group were stimulated by E2. It is suggested that ER status alone can not predict the response of cultured cells to E2 in clinical breast cancer. Cell growth of 11/35 (31%) of the ER-positive cases and that of 8/19 (42%) of the ER-negative cases was inhibited by E2. Since the cases inhibited by E2 could not be distinguished by ER status alone, an assay system based on a quantitative proliferative response was considered necessary. There were 20 (83%) cases of inhibition by TAM among the 24 stimulated by E2. Only 18/35 (51%) of the ER-positive group exhibited growth inhibition by TAM. In our (CSP) assay, 20 (83%) of the 24 cases stimulated by E2 were inhibited by TAM, 10 (91%) of the 11 E2-insensitive cases were insensitive to TAM and 13 (68%) of the 19 cases inhibited by E2 were stimulated by TAM. In short, TAM response and E2 response tended to be inversely related (43/54 = 80%, P < 0.01). Furthermore, the E2-response rate showed a good correlation with the TAM-response rate (R2 = 0.825). These results indicate the feasibility of predicting individual tumor responses to either E2 or TAM by using CSPs.

During the period 1986-93 22 patients were diagnosed as having primary hemochromatosis. Only 11 of them had elevated aminotransferases. Transferrin saturation was higher > 63% in 17 (77%) and serum-ferritin was higher in all the patients. (257 mumol/l to 6,500 mumol/l). A percutaneous liver biopsy was performed in 20 patients, all of whom showed a characteristic grading from 2 + to 4+ using Perls' stain. Two males had cirrhosis with simultaneous hepatocellular carcinoma, and another two had cirrhosis. One patient had diabetes mellitus type I. We conclude that fasting serum-iron and transferrin should be determined in all subjects over 40 years of age and in patients with chronic elevation of liver enzymes. If transferrin saturation is higher than 50% in females and 60% in males, serum ferritin should be determined. A percutaneous liver biopsy should be performed if both values are higher than normal. Screening of siblings is important because of the autosomal recessive pattern of inheritance.

Heparin (HEP) prevents thrombus formation (TF) and thrombus growth (TG), by accelerating thrombin (THR) inhibition by antithrombin III (ATIII). Recent studies suggest that dermatan sulphate which catalyzes thrombin inhibition by heparin cofactor II (HCII), can inhibit TF and TG as effectively as HEP. This study compared the antithrombotic effects of HEP and another agent, Sulodexide (SLX) which catalyzes thrombin inhibition by ATIII and HCII simultaneously. TF was induced in rabbit jugular veins, using the stasis/hypercoagulation model. TG was measured as the accretion of 125I-fibrin onto existing thrombi in rabbit jugular veins. HEP and SLX inhibited TF when given in doses of 10 and 5 anti-thrombin U/kg, respectively. SLX (16 anti-thrombin U/kg or 260 micrograms/kg) was more effective than HEP (120 anti-thrombin U/kg or 800 micrograms/kg) in preventing TG when administered either as a bolus or by continuous infusion. These data suggest that agents which accelerate THR inhibition by both ATIII and HCII simultaneously, can inhibit TF and TG with less systemic anticoagulation than comparable antithrombotic doses of HEP.

In previous studies, we have shown that allelic loss on chromosome 17p, on which the p53 gene is located, is very frequent, and loss-of-function mutations of the p53 gene are closely associated with the tumorigenesis of esophageal cancer. In this study, we performed allelotype analysis to investigate whether other tumor suppressor genes are also involved in esophageal cancer. Using 55 polymorphic DNA markers covering every autosomal arm except 13p, 21p, and 22p, restriction fragment length polymorphism analysis was performed on 36 esophageal squamous cell carcinomas (ESCs) and their adjacent normal tissue samples. Frequent loss of heterozygosity (LOH) of > 30% of the informative cases was observed on chromosomes 3p (41.1%), 5q (52.6%), 6p (30.4%), 8p (33.3%), 9p (35.7%), 9q (30.8%), 11p (32.4%), 13q (52.7%), 17p (55.2%), 17q (33.3%), 18q (45.7%), and 19q (30.4%). Among these, LOH on 5q, 13q, 17p, and 18q was previously reported in ESC and is considered to involve the APC, RB, p53, and DCC genes, respectively. However, our deletion analysis of chromosome 18q revealed that the region commonly lost did not include the DCC locus, suggesting that a possible tumor suppressor gene on 18q other than the DCC gene is involved in ESC. We screened 60 primary ESC tumors and 20 cultured ESC cell lines for the mutation of the APC gene within a mutation cluster region in exon 15, where the "hot spot" of somatic mutation for colorectal and pancreatic cancers is thought to be. We could not find any mutation despite the high frequency of LOH on chromosome 5q. We also analyzed the relationship between the clinicopathological data and the allelic loss and found that LOH on chromosomes 6p and 13q was associated with poor prognosis.

Since tumor suppressor gene DCC exhibits amino acid sequence homology to the neural cell adhesion molecule, there is a possibility that DCC might be related to tumor metastasis. In the present study, we examined 51 cases of primary esophageal carcinomas with regard to point mutations and loss of the DCC gene. We detected point mutations in two cases by screening using polymerase chain reaction-single strand conformation polymorphism analysis. When we determined the sequences, one case with lymph node metastasis showed an ATG (Met) to ACG (Thr) missense mutation in codon 168. Another case showed a CGA (Arg) to GGA (Gly) mutation in codon 201, which might be a polymorphic change, and two other mutations resulting in no amino acid change. We also examined loss of heterozygosity of the DCC gene. Forty-four of the 51 cases (86%) were informative, and among them 10 cases (23%) showed allelic deletion. The further away the lymph node metastasis was from the primary tumor, the higher the frequency of allelic deletions became. We also found allelic deletions in moderately and poorly differentiated squamous cell carcinomas but not in well differentiated ones. These results indicate that alterations of the DCC gene are related to the degree of lymph node metastasis and the degree of differentiation.

<h4>Background/aims</h4>The pathogenesis of pancreatic cancer is poorly understood. The multigenetic nature of carcinogenesis has been best documented in colon cancer. The relevance of this model was suggested for other epithelial tumors. Only advanced stages of pancreatic cancer are usually detected because of late diagnosis. Analysis of accumulated, diverse genetic changes could allow further understanding of putative mechanisms involved in tumor development. Activated c-Ki-ras oncogene has been shown to be a frequent event. However, additional alterations of tumor suppressor genes are expected. Therefore, concomitant genetic changes of p53 and deleted in colon carcinoma (DCC) in pancreatic carcinoma cell lines and primary tumors were analyzed.<h4>Methods</h4>p53 protein and transcript expression were revealed by immunocytochemistry and immunohistochemistry, immunoassay, and Northern blot analysis. p53 mutations were identified by sequence analysis. DCC expression was investigated by reverse-transcription polymerase chain reaction.<h4>Results</h4>p53 overexpression was observed in 9 of 12 cell lines. p53 point mutations were confirmed in seven cell lines overexpressing p53. The majority of cell lines showed concomitant p53 and DCC alterations. Four of 6 primary tumors overexpressing p53 also showed loss of DCC expression.<h4>Conclusions</h4>p53 and DCC genetic changes are associated with pancreatic cancer and the frequently activated c-Ki-ras oncogene. Therefore, the multihit model of carcinogenesis could prove relevant for pancreatic cancer.

The Neisseria gonorrhoeae lipooligosaccharide biosynthetic gene lsi-1 is preceded by a 281-bp non-protein-encoding sequence, lsi-3, that contains two pairs of inverted repeats. Gonococcal chromosomal lsi-xylE gene fusions were generated to measure the effect of the secondary structure on transcriptional attenuation. The data obtained indicate that lsi-3 and lsi-1 are not transcriptionally linked and therefore that lsi-3 is not involved in the regulation of lsi-1.

Hereditary nonpolyposis colon cancer (HNPCC) is an autosomal dominant trait responsible for approximately 6% of colorectal cancers. Linkage of the HNPCC trait to the D2S123 locus on 2p15-16 has previously been reported in two families. This HNPCC locus is now designated "COCA1." We have tested seven Canadian HNPCC families, who have a variety of clinical presentations, for linkage to a panel of microsatellite polymorphisms in the vicinity of D2S123. One family was clearly linked to the COCA1 locus (LOD = 4.21), and a second family is likely to be linked (LOD = 0.92). In three families linkage was excluded. In the remaining two families the data were inconclusive. In the linked family, individuals with cancer of the endometrium or ureter share a common haplotype with 12 family members with colorectal cancer. This supports the suspected association between these extracolonic neoplasms and the HNPCC syndrome. In addition, five of the six individuals with adenomatous polyps (but no colorectal cancer) have the same haplotype as the affected individuals, while the sixth carries a recombination. One individual with colorectal cancer carries a recombination that places the COCA1 locus telomeric to D2S123. This study localizes the COCA1 gene to an 8-cM region that is consistent with the location of the hMSH2 gene. We also confirm that families presently classified as HNPCC are genetically heterogeneous.

In this study we have screened a series of 29 primary leiomyosarcomas for abnormalities of both the p53 gene and the MDM2 gene, which encodes a p53-associated protein. SSCP (single-strand conformation polymorphism) analysis and direct sequencing of polymerase chain reaction (PCR)-amplified DNA were used to establish that 6/29 tumours possessed point mutations of the p53 gene. Using a monoclonal antibody that recognises the p53 protein in immunohistochemical staining experiments, we observed overexpression of the p53 protein in five of the six tumours containing point mutations in the p53 gene. Southern analysis of tumour DNA revealed that 2/29 tumours demonstrated amplification of the MDM2 gene. When considered together, these results indicate that alterations in both the p53 gene and MDM2 gene are important in the development of a significant minority of leiomyosarcomas. In addition, we have demonstrated a significant association between the presence of abnormalities of the p53 gene or MDM2 genes in leiomyosarcomas and a more advanced clinicopathological stage (P = 0.03). We have also examined the role of the DCC tumour-suppressor gene in the development of human soft-tissue tumours in a variety of histological types. Except for evidence of a rearrangement in a single leiomyosarcoma cell line, SK-UT-1, we have found no direct evidence to support a role for mutation of the gene in the development of human soft-tissue tumours.

Four inherited neurodegenerative diseases are linked to abnormally expanded repeats of glutamine residues in the affected proteins. Molecular modeling followed by optical, electron, and x-ray diffraction studies of a synthetic poly(L-glutamine) shows that it forms beta-sheets strongly held together by hydrogen bonds. Glutamine repeats may function as polar zippers, for example, by joining specific transcription factors bound to separate DNA segments. Their extension may cause disease either by increased, nonspecific affinity between such factors or by gradual precipitation of the affected proteins in neurons.

Earlier studies have shown that the thymidine kinase-negative baby hamster kidney (BHKTK-) cell lines expressing constitutively the herpes simplex virus 1 (HSV-1) glycoprotein D (gD), designated BJ, restrict infection by HSV-1 at the level of virus entry. U10, a HSV-1 mutant not restricted by the BJ cells, carried the substitution of proline for Leu25 in the gD gene, suggesting that gD encodes a specialized domain which precludes virus entry into cells expressing gD. Analyses of a new series of 36 unrestricted viral mutants showed the following. (i) Only two mutants contained mutations at a site which did not overlap with the previously reported mutation. A representative of a previously mapped mutant and one of the two new mutants were examined in detail. Thus, in the gD of mutant U30 Ala185 was replaced by threonine, whereas in gD of U21, Ala185 and Leu25 were replaced with threonine and proline, respectively. U30 and U21 multiplied better than the wild-type parent virus in the parental BHKTK- cells. (ii) Transfer of the gD gene from U21 or U30 to wild-type parent virus or to the gD- virus FgD beta yielded recombinants which, while capable of infecting BJ cells, were considerably less efficient than the parent unrestricted mutants, suggesting that the latter contained additional mutations which were responsible in part for the unrestricted phenotype. Conversely, marker rescue of mutant viruses with wild-type gD reduced but did not abrogate entirely the unrestricted phenotype. (iii) Mutations in gD which conferred the unrestricted phenotype were not random. (iv) gD plays a role in the restriction, inasmuch as preincubation of cells expressing gD with antibodies to gD abolished restriction. (v) In mutant R5000, the gD substitution Ser140 to Asn was capable of overcoming a restriction of a BHKTK- clonal line which does not express gD but conferred very low ability to replicate on BJ cells. We conclude that (a) uncloned stocks of BHKTK- cells exhibit a low level restriction to infection with wild-type virus, (b) clonal lines of BHKTK- cells which vary with respect to the stringency of restriction express either allelic genes differing in the properties of their products or products of different genes, and (c) both the restricted and unrestricted phenotypes reflect the interactions of gD with these cellular products. The implications of these conclusions with respect to the restriction imposed on BHK cells by the expression of gD are discussed.

<h4>Background and purpose</h4>The underlying embolic material detected by transcranial Doppler ultrasound in patients with prosthetic heart valves remains unknown. We undertook this study to evaluate the relation between the number of Doppler emboli signals and the activity of the coagulation system.<h4>Methods</h4>Patients with various types of prosthetic valves (n = 120) and patients in atrial fibrillation (n = 20) were monitored for 30 minutes using transcranial Doppler with a 2-MHz probe. The plasma concentrations of cross-linked D-dimer, antithrombin-III, and thrombin-antithrombin III complex were measured.<h4>Results</h4>No correlation between the levels of any of the hematologic parameters and the number of emboli was demonstrated in the studied groups. The D-dimer levels were significantly higher in patients with mechanical prosthetic valves with an international normalized ratio under 2.0 compared with those with an international normalized ratio between 2 and 3.5 or above 3.5, and in patients with Medtronic-Hall versus Björk-Shiley or Carpentier-Edwards valve prostheses.<h4>Conclusions</h4>The lack of correlation between the activity of the coagulation system and the number of Doppler emboli in patients with prosthetic valves suggests that the underlying embolic material in these patients is not thrombotic. Our results also suggest that an increase of the anticoagulation intensity to an international normalized ratio above 3.5 does not result in a further decrease of the activity of the unstimulated coagulation system in patients with mechanical prosthetic valves.

A novel rat model was developed in which furan combined in a unique synergistic manner with bile duct ligation to induce replacement of most of liver with well-differentiated hyperplastic bile ductules. Multiple tissue sections of liver from Fischer 344 male rats first subjected to a bile duct ligation and 1 week later given furan by gavage at 45 mg/kg body weight, once a day, five times weekly for 5 to 6 weeks, exhibited a mean percent of bile ductule tissue per total liver section area of 72.6 +/- 16.3% compared to control values of 20.0 +/- 4.2% for bile duct-ligated rats that received corn oil by gavage instead of furan and 11.9 +/- 3.1% for rats that were given a sham operation followed by furan. This dramatic difference was also reflected by the very high mean gamma-glutamyl transpeptidase specific activity of liver homogenates from the bile duct-ligated/furan-treated rats, which was approximately 8 x 10(3) nmoles p-nitroaniline/mg protein/hour versus values of approximately 2 x 10(3) for bile duct-ligated/corn oil control, approximately 1 x 10(3) for sham-operated/furan-treated control, and 44.9 for untreated rat. The data presented support a potentially powerful experimental model for investigating bile ductular cell functions, differentiation, and proliferation.

Tumorigenesis has been shown to proceed through a series of genetic alterations involving protooncogenes and tumor-suppressor genes. Investigation of genomic instability of microsatellites has indicated a new mechanism for human carcinogenesis in hereditary nonpolyposis colorectal cancer and sporadic cancer and this instability has been shown to be related to inherited predisposition to cancer. This study was conducted to determine whether such microsatellite instability is associated with the evolution of chronic myelogenous leukemia (CML) to the blast crisis. Nineteen CML patients clinically progressing from the chronic phase to accelerated phase or blast crisis and 20 other patients in the CML chronic phase were studied. By polymerase chain reaction assay, DNAs for genomic instability in five separate microsatellites in chromosome arms 5q (Mfd27), 17p (Mfd41), 18q (DCC), 3p (CI3-9), and 8p (LPL) were examined. Differences in unrelated microsatellites of chronic and blastic phase DNAs in 14 of 19 patients (73.7%) were demonstrated. Somatic instability in five microsatellites, Mfd27, Mfd41, DCC, CI3-9, and LPL, was detected in 2 of 19 (10.5%), 8 of 19 (42.1%), 11 of 19 (57.9%), 4 of 17 (23.5%), and 4 of 17 (23.5%) cases. In 10 of 19 cases (52.6%), genetic instability in at least two of five microsatellites was observed and was categorized as replication error (RER+) phenotype. CML evolution cases with myeloid, lymphoid, and mixed phenotypes and the blast crisis and accelerated phase showed somatic instability in a number of microsatellites. No alterations in leukemic cells at the chronic phase could be detected in any microsatellites. These data indicate instability of microsatellites (RER+) but not familial predisposition to possibly be a late genetic event in the evolution of CML to blast crisis. In the microsatellite of the DCC gene, complicated alterations in band patterns caused by instability as well as loss of heterozygosity (LOH) were observed in 13 of 19 cases (68.4%): instability in 9 cases, instability plus LOH in 2 cases, and only LOH in 2 cases. These highly frequent alterations in microsatellites, including instability and LOH, suggesting that secondary events due possibly to loss of fidelity in replication and repair machinery may be significantly associated with CML evolution.