The first synthesis of clausenamine-A and cytotoxic activities of three biscarbazole analogues against cancer cells

Clausemine-A (3), isolated from the stem and root bark of Clausena excavata, was synthesized using Suzuki cross-coupling and Oxidative coupling as the key step. Compound 3, and the other two structurally related biscarbazoles 1 and 2, showed potent cytotoxic activities against a variety of human cancer cell lines in vitro.

[Long-term observation on two types of surgical operations for idiopathic hemifacial spasm]

OBJECTIVE

To evaluate and compare the long-term curative effects of two types of surgical operations, microvascular decompression (MVD) and microneurovascular decompression neurocombing neurotraction draw (MVDCTD) for idiopathic hemifacial spasm (IHFS).

METHODS

Five hundred and fifty-four patients with complete medical records and with at least 3-year followed-up had been collected since 1985.

RESULTS

Of 148 MVD-treated cases with the longest follow-up of 13 years and 9 months, 117 cases were free of symptoms, giving a 79.05% cure rate. Thirty-one patients had recurrence of the symptoms, giving a 20.95% recurrence rate. Of 406 cases treated by MVDCTD with the longest follow-up of 12 years and 3 months, 374 were cured, giving a 92.12% cure rate, and 32 had recurrences of symptoms, giving a 7.88% recurrence rate. Most of them recurred within 2 years after the operation. Complications were sensorineural hearing loss in 31 patients (23 temporary, 8 permanent), temporary tinnitus in 22, temporary postoperative facial weakness in 78, and postoperative meningitis in 34 (3.13%, 33 cases were controlled with antibiotics and 1 patient died).

CONCLUSION

The vascular compression at the root of the facial nerve is a main cause of IHFS, and the abnormal function of the facial nucleus is also one of the causes. MVDCTD for IHFS is characterized by its high curative rate, low recurrent rate and stable long-term effect, and is superior to the MVD.

alpha(1,3)fucosyltransferases expressed by the gain-of-function Chinese hamster ovary glycosylation mutants LEC12, LEC29, and LEC30

Gain-of-function glycosylation mutants provide access to glycosylation pathways, glycosylation genes, and mechanisms that regulate expression of a glycotype. Previous studies have shown that the gain-of-function Chinese hamster ovary (CHO) mutants LEC12, LEC29, and LEC30 express an N-ethylmaleimide-resistant alpha(1, 3)fucosyltransferase (alpha(1,3)Fuc-T) activity that is not detected in CHO cells and that generates the Lewis(X) but not the sialyl-Lewis(X) determinant. The three mutants differ, however, in lectin resistance properties, expression of fucosylated antigens, and in vitro alpha(1,3)Fuc-T activities. In this paper we show that each mutant expresses Fuc-TIX, but only LEC30 cells express Fuc-TIV. Using genomic PCR and reverse-transcriptase (RT)-PCR strategies, we isolated coding portions of the CHO Fut4 and Fut9 genes. Each gene is present in a single copy in the CHO and mutant genomes. The Fut4 gene is expressed only in LEC30 cells, while all three mutants express the Fut9 gene. Interestingly, the fucosylation phenotypes of LEC12 and LEC29 cells do not correlate with the relative abundance of their Fut9 gene transcripts (LEC29 >> LEC12). Compared to LEC29 cells, LEC12 cells have an approximately 40-fold higher in vitro alpha(1,3)Fuc-T activity and bind the VIM-2 monoclonal antibody, whereas LEC29 cells do not bind VIM-2. Mixing experiments did not detect Fuc-TIX inhibitory activity in LEC29 cell extracts, and CHO cells expressing a transfected Fut9 gene behaved like LEC12 cells. Therefore, it seems that LEC29 cells may not translate their more abundant Fut9 gene transcripts efficiently or may not synthesize appropriate acceptors for internal alpha(1,3)fucosylation. Alternatively, LEC12 cells may possess, in addition to Fuc-TIX, a novel alpha(1,3)Fuc-T activity.

Factors that predict the referral of breast cancer patients onto clinical trials by their surgeons and medical oncologists

PURPOSE

To improve understanding of physicians' reluctance to refer patients to clinical trials.

METHODS

This study was conducted in a large metropolitan region from 1993 to 1995 using a two-staged population-based sampling strategy. A total of 147 physicians discussed 245 patient cases and their own knowledge, attitudes, and practices toward clinical trials.

RESULTS

Ninety-three patients (38. 0%) were offered a trial, and 49 (52.7%) of them agreed to participate. Forty-five patients (18.4%) actually received their adjuvant therapy on trial. Older patients and those with a poorer prognosis were less likely to be referred. Patients who delayed their decision were more than three times as likely to participate in a trial and more than eight times as likely to participate when they were reported to be actively involved in making the decision. Generally, physicians in university settings and who had formal support from a cooperative group were more likely to refer patients to trials. More specifically, surgeons referred more patients to trials when they felt comfortable explaining trials or believed that treatment should not stray from protocol. Oncologists were less likely to make referrals if they perceived the paperwork to be onerous or entry requirements to be too stringent. Surgeons' participation in recommending adjuvant therapy to patients resulted in more trial referrals unless they treated their patients with tamoxifen.

CONCLUSION

(1) Physicians still need to overcome attitudinal and practical barriers to trial participation, (2) more support for physicians is needed, (3) surgeons may play a pivotal role in the recruitment of patients to adjuvant therapy trials, and (4) garnering patient enthusiasm for trial participation and involving them in the choice of adjuvant therapy may be key components to increasing trial enrollment.

Hydrogen peroxide induces contraction and raises [Ca2+]i in canine cerebral arterial smooth muscle: participation of cellular signaling pathways

The effects of hydrogen peroxide (H2O2) on isolated canine basilar arteries, and single smooth muscle cells isolated from these arteries, were investigated in the present study. Exposure of isolated endothelium-intact and denuded arterial rings to H2O2, at concentrations of 2.2x10(-5) M to 4.4x10(-3) M, produced concentration-dependent contractile responses. Removal of the endothelium attenuated, but did not eliminate the contractions. H2O2-induced contractions were inhibited, to different degrees, by preincubation of the vessels with low concentrations of staurosporine or bisindolylmaleimide I HCl [antagonists of protein kinase C (PKC)], Gö6976 (a PKCalpha and PKCbeta1 selective antagonist), genistein (an antagonist of protein tyrosine kinase), PD-98059 (an antagonist of mitogen-activated protein kinase), wortmannin [an antagonist of phosphatidylinositol 3 (PI3)-kinases], and LY-294002 (an antagonist of PI3-kinases). These agents were also found to relax arteries precontracted by H2O2. Removal of extracellular Ca2+ or pretreatment of the vessels with 5.0 microM verapamil markedly attenuated the contractions. Complete inhibition of the contractile response was obtained after buffering intracellular Ca2+ with BAPTA-AM. A variety of specific pharmacological antagonists of several known vasoconstrictors neither inhibited nor attenuated the H2O2-induced contractions. Exposure of smooth muscle cells to H2O2 (4.4x10(-6) M to 4.4x10(-4) M) significantly raised intracellular Ca2+ ([Ca2+]i) within 20 s. This was abolished in the absence of extracellular Ca2+ or after application of 5.0 microM verapamil. Pretreatment of the cells with low concentrations of staurosporine, bisindolylmaleimide I, Gö6976, genistein, PD-98059, wortmannin, and LY-294002 markedly suppressed the H2O2-mediated [Ca2+]i elevation. The present findings suggest that hydrogen peroxide, in vitro, produces endothelium-dependent and independent contractions of canine basilar arteries, which are clearly Ca2+-dependent and are not associated with release of endogenous vasoconstrictors. Several intracellular signal transduction systems, such as PKC (both Ca2+-dependent and Ca2+-independent), protein tyrosine phosphorylation, IP3, mitogen-activated protein kinase and PI3 kinase appear to play a role in the H2O2-induced contractions in cerebral arterial muscle.

Prognostic clinicopathologic factors, including immunologic expression in diffuse large B-cell lymphomas

The aim of this study was to assess the clinical significance and potential prognostic value of the expression of a panel of surface markers, proliferating, suppressor and oncogenic proteins in diffuse large B-cell lymphomas (DLBCL). Biopsies were collected from 158 patients with DLBCL and analyzed immunohistochemically for p53, p21/WAF1, bcl-2, cyclin-D1, bcl-6, mdr, CD5, CD30, epithelial membrane antigen (EMA), Ki-67 and c-myc positive tumor cells. Among these, 76 young and middle-aged patients (20-65 years) were selected to investigate the relationship between protein expression, clinical features, and survival. Survival analysis showed that advanced stage, high lactic dehydrogenase level, and high International Prognostic Index (IPI) were poor prognostic factors associated with a shorter overall survival (OS) and disease-free survival (DFS) times. A high p53 expression and low bcl-6 expression were associated with a shorter DFS time. The histological variant type, cyclin-D1+ CD5+ DLBCL, positive epithelial membrane antigen (EMA+) CD30- DLBCL, high bcl-2 expression, and low Ki-67 proliferation activity tended to be associated with worse survival, but the correlations were not statistically significant. In the multivariate analysis, the most significant factors were age, followed by IPI and last p53. The expression of p21/WAF1, mdr, and c-myc proteins did not influence OS and DFS. The expression of p53 and bcl-6 proteins may be useful prognostic indicators in DLBCL. Cyclin-D1+ CD5+ or EMA+ CD30- DLBCL tended to predict a worse survival and may probably bear a significant prognostic value worthy of consideration. Overall, clinical factors appeared to be more important than biologic parameters in determining the prognosis of diffuse large B-cell lymphomas.

Hydrogen peroxide-induced endothelium-dependent relaxation of rat aorta involvement of Ca2+ and other cellular metabolites

In phenylephrine-precontracted rings, H2O2 produced an endothelium-dependent relaxation at concentrations of 4.4 x 10(-7) to approximately 4.4 x 10(-5) M. Removal of extracellular Ca2+ ([Ca2+]0) markedly attenuated the relaxant effects of H2O2. Complete inhibition of the H2O2 relaxant action was obtained after buffering intracellular Ca2+ ([Ca2+]i) in endothelial cells, with 10 microM acetyl methyl ester of bis (o-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM). These relaxant effects of H2O2 were nearly abolished by 15 x 10(-5)M N(G)-monomethyl-arginine (L-NMMA) or 5 x 10(-5) M N(G)-nitro-L-arginine (L-NAME) and were attenuated markedly by the presence of either 10(-6) M Fe2+, 10(-6) M Fe3+, or 5 x 10(-6) M methylene blue. These inhibitory effects of L-NMMA or L-NAME could be reversed partly by 5 x 10(-5) M L-arginine. These Fe(2+)- and Fe(3+)-induced inhibitions of H2O2-stimulated relaxation were reduced significantly by either 1.0 mM deferoxamine (a Fe2+ chelator) or 100 microM dimethyl sulfoxide (DMSO). In addition, 17-octadecynoic acid (2.5 microM) or proadifen (10 microM) (both antagonists of cytochrome P450 metabolism of fatty acids) markedly decreased the H2O2 relaxant effects. Proadifen (10 microM) produced concentration-dependent impairment of vasorelaxation to acetylcholine. A variety of amine antagonists and a cyclo-oxygenase inhibitor all fail to interfere with or attenuate the H2O2-induced relaxations. Our observations suggest that, at suitable pathophysiologic concentrations, H2O2 could induce release of an endothelium-derived relaxing factor, probably nitric oxide, from endothelial cells. The H2O2 relaxant effects are clearly Ca(2+)-dependent and require formation of cyclic guanosine monophosphate (cGMP). These vasorelaxing effects of H2O2 appear to be induced by H2O2 itself. Hydrogen peroxide may stimulate production of some unknown metabolites metabolized by cytochrome P450-dependent enzymes.

[Determination of the content of aminopyrine in antongding injection by orthogonal function spectrophotometry]

Determination of the content of aminopyrine in the antongding injection by orthogonal function spectrophotometry was reported in this paper. The six wavelengths for the determination are 257, 261, 265, 269, 273 and 277 nm. The concentration of aminopyrine in the range of 5-25 microg x mL(-1) is in a good linear relation to P2, and the regression equation is P2 = + 0.018 - 0.032 9c, r = 0.999 9. The average recovery and relative standard deviation are 100.3% and 0.40%, respectively. On the basis of the data observed it is concluded that this method shows no obvious difference as compared with Hebei province pharmacy regulation.

Low concentrations of ethanol deplete type-2 astrocytes of intracellular free magnesium

The acute effects of low concentrations of ethanol on intracellular free magnesium ions ([Mg2+]i) in cultured type-2 astrocytes were studied by digital imaging microscopy using the Mg2+ fluorescent probe, mag-fura-2. In 0-mM ethanol, the basal level of [Mg+]i was 124.7+/-2.56 microM with a heterogeneous distribution within the cells. Treatment of the cells with 10 and 25 mM ethanol (10 min) resulted in rapid concentration-dependent reduction in [Mg2+]i; the greater the concentration of alcohol, the greater the depletion of [Mg2+]i. Exposure of cells to 10 and 25 mM resulted in approximately 27 and 50% reductions in [Mg2+]i, respectively. Reincubation in normal Mg2+-physiological buffer solution restored [Mg2+]i levels. These observations may suggest that acute "binge drinking" of ethanol, which often results in cerebral ischemia and stroke, may do so as a result of depletion of astrocytic [Mg2+]i, possibly producing disruption of the blood-brain barrier.

Expression and activity of vitamin D-metabolizing cytochrome P450s (CYP1alpha and CYP24) in human nonsmall cell lung carcinomas

Extrarenal 25-hydroxyvitamin D3-1alpha-hydroxylase is believed to play a major role in the pathogenesis of hypercalcemia associated with various types of granulomatous and lymphoproliferative diseases and certain solid tumors. In this paper, we describe the cloning of the cytochrome P450 component of the extrarenal enzyme from a human nonsmall cell lung carcinoma, SW 900. The cytochrome P450 for the extrarenal 1alpha-hydroxylase has an amino acid sequence identical to that of the cytochrome P450 component of the CYP1alpha, the renal form of the enzyme, and appears to be a product of the same gene. CYP1alpha messenger RNA (mRNA) and 1alpha-hydroxylase enzyme activity were detected in two (SW 900, SK-Luci-6) of a series of five nonsmall cell lung carcinoma cell lines. All five lung cell lines were cultured with the same medium under the same conditions, but only two of the five expressed 1alpha-hydroxylase enzyme; two others (WT-E, Calu-1) expressed high levels of the reciprocally regulated enzyme, 25-hydroxyvitamin D3-24-hydroxylase, with its specific cytochrome P450 component, CYP24. Although under basal conditions the lung cell line SW 900 expressed only CYP1alpha and showed 1alpha-hydroxylase enzyme activity, when treated with small concentrations of 1alpha,25-dihydroxyvitamin D3 or high concentrations of 25-hydroxyvitamin D3, it began to express CYP24 and exhibit 24-hydroxylase enzyme activity. Somewhat surprisingly, SW 900 cells still had detectable CYP1alpha mRNA some 24 h after vitamin D treatment despite the fact that 1alpha-hydroxylase enzyme activity was unmeasurable. These data are consistent with the emerging hypothesis that vitamin D through its active form does not directly turn off CYP1alpha mRNA production but, rather, strongly stimulates CYP24, thereby masking CYP1alpha activity. The factor(s) responsible for the basal expression of CYP1alpha in SW 900 and SK-Luci-6 is currently unknown.

[Assay of diclofenac sodium and codeine phosphate in tablet by multiwavelength K-factor spectrophotometry]

Assay of diclofenac sodium and codeine phosphate in tablet is reported in this paper. The calibration curves were linear over the range of 11.18-25.40 microg/mL of diclofenac sodium and over the range of 6.785-15.42 microg/mL of codeine phosphate. The average recoveries and relative standard deviations of diclofenac sodium and codeine phosphate were 100.1%, 0.36% and 100.7%, 0.80%, respectively. The method is simple and rapid, and the results are satisfactory.

The gain-of-function Chinese hamster ovary mutant LEC11B expresses one of two Chinese hamster FUT6 genes due to the loss of a negative regulatory factor

The LEC11 Chinese hamster ovary (CHO) gain-of-function mutant expresses an alpha(1,3)fucosyltransferase (alpha(1,3)Fuc-T) activity that generates the LeX, sialyl-LeX, and VIM-2 glycan determinants and has been extensively used for studies of E-selectin ligand specificity. In order to identify regulatory mechanisms that control alpha(1,3)Fuc-T expression in mammals, mechanisms of FUT gene expression were investigated in LEC11 cells and two new, independent mutants, LEC11A and LEC11B. Northern and ribonuclease protection analyses, using probes that span the coding region of a cloned CHO FUT gene, detected transcripts in each LEC11 mutant but not in CHO cells or other gain-of-function CHO mutants that express a different alpha(1,3)Fuc-T activity. Coding region sequence analysis and alpha(1,3)Fuc-T acceptor specificity comparisons with recombinant human Fuc-TV and Fuc-TVI showed that the cloned FUT gene is orthologous to the human FUT6 gene. Southern analyses identified two closely related FUT6 genes in the Chinese hamster, whose evolutionary relationships are discussed. The blots showed that rearrangements had occurred in LEC11A and LEC11 genomic DNA, consistent with a cis mechanism of FUT6 gene activation in these mutants. By contrast, somatic cell hybrid analyses revealed that LEC11B cells express FUT6 gene transcripts due to the loss of a trans-acting, negative regulatory factor. Sequencing of reverse transcriptase-polymerase chain reaction products identified unique 5'- and 3'-untranslated region sequences in FUT6 gene transcripts from each LEC11 mutant. Northern and Southern analyses with gene-specific probes showed that LEC11A cells express only the cgFUT6A gene (where cg is Cricetulus griseus), whereas LEC11 and LEC11B cells express only the cgFUT6B gene. In LEC11A x LEC11B hybrid cells, the cgFUT6A gene was predominantly expressed, as predicted if a trans-acting negative regulatory factor functions to suppress cgFUT6B gene expression in CHO cells. This factor is predicted to be a cell type-specific regulator of FUT6 gene expression in mammals.

[Simultaneous determination of molybdenum and chromium by artificial neural networks spectrophotometry]

In this paper, a three-layer artificial neural networks were applied to simultaneous determination of molybdenum and chromium by spectrophotometry. The apparent molar absorptivities of the complex of molybdenum and chromium are 1.4 x 10(5) L x mol(-1) x cm(-1) and 3.7 x 10(4) L x mol(-1) x cm(-1), respectively. A method has been developed for simultaneous determination of molybdenum and chromium in steel with satisfactory results. The paralysis in the procedure of training about ANN has been avoided with the improved back propagation algorithms. The simple transformation method for target vectors and criterion function convenient for selection of the parameters about the networks has been put foward.

A disulfide-bound HIV-1 V3 loop sequence on the surface of human rhinovirus 14 induces neutralizing responses against HIV-1

An immunogenic sequence from the V3 loop of the MN isolate of human immunodeficiency virus type 1 (HIV-1), His-Ile-Gly-Pro-Gly-Arg-Ala-Phe, was transplanted onto a surface loop of the VP2 capsid protein of human rhinovirus 14. To optimize for virus viability and immunogenicity of the transplanted sequence, the HIV sequence was flanked by (1) a cysteine residue that could form a disulfide bond and (2) randomized amino acids (in either of two arrangements) to generate numerous presentations of the Cys-Cys loop. The location for engineering in VP2 was chosen by searching the geometries of disulfide-bound loops in known protein structures. A model for the structure of the transplanted V3 loop sequence was developed using molecular dynamics and energy minimization calculations. Proteolytic digestion with and without reducing agent demonstrated the presence of the disulfide bond in the chimeric virus examined. Monoclonal and polyclonal antibodies directed against the V3 region of the HIV-1MN strain potently neutralized two chimeric viruses. Guinea pig antisera against two chimeric viruses were able to neutralize HIV-1MN and HIV-1ALA-1 in cell culture. The ability of chimeric viruses to elicit antibodies capable of neutralizing the source of the transplanted sequence could be favorable for vaccine development.

[A study on expressions of P53 protein and proliferating cell nuclear antigen in malignant eyelid tumors]

OBJECTIVE

To observe the relationship between P53 gene mutation and malignant eyelid tumor.

METHODS

The expressions of P53 protein and proliferating cell nuclear antigen (PCNA) in 102 cases with malignant eyelid tumors were examined by labelled streptravidin biotin (LSAB) immunohistochemical technique.

RESULTS

Although overexpression of P53 protein was not detected in normal eyelid cutaneous epithelium, meibomian gland and mild epithelial dysplasia, the positive rate of P53 increased in degree in moderate and severe dysplasia, carcinoma in situ and invasive tumors, and PCNA labeling index (PI) progressively increased too. Overexpression of P53 protein was detected in 30/53 cases of basal cell carcinoma (BCC), 16/32 cases of squamous cell carcinoma (SCC), 10/17 cases of meibomian gland carcinoma, and the intensity of P53 protein immunostaining increased with the lowering in the degree of histological differentiation. The mean PCNA labeling index was 38.1 +/- 31.1, 38.3 +/- 30.1, 42.6 +/- 32.0 respectively in BCC, SCC and meibomian gland carcinoma. The PI value in tumor tissue with positive P53 protein expression was higher than that in tissues with its negative expression (P < 0.05).

CONCLUSIONS

The gene mutation of P53 protein might play an important role in the pathogenesis of malignant eyelid tumors, it may be one of the factors that can lead to abnormal hyperactivity of cell proliferation and it possibly can be a malignant sign in the progression of a tumor.

Small RNAs in Escherichia coli

Bacterial cells contain several small RNAs (sRNAs) that are not translated. These stable, abundant RNAs act by multiple mechanisms, such as RNA-RNA basepairing, RNA-protein interactions and intrinsic RNA activity, and regulate diverse cellular functions, including RNA processing, mRNA stability, translation, protein stability and secretion.

Mg2+ modulates membrane sphingolipid and lipid second messenger levels in vascular smooth muscle cells

In vitro studies with smooth muscle cells from rat aorta and dog cerebral blood vessels indicate that variation in free Mg2+, within the pathophysiological range of Mg2+ concentrations, found in human serum, causes sustained changes in membrane phospholipids and lipid second messengers. Incorporation of [3H]palmitic acid into phosphatidylcholine (PC) and sphingomyelin (SM) was altered within 15-30 min after modifying the extracellular Mg2+ ion level ([Mg2+]o). Decreased Mg2+ produced a fall in both [3H]SM and [3H]PC over the first 2 h. After an 18-h incubation, the [3H]PC/[3H]SM ratio changed from about 20:1 to about 50:1. Increased [Mg2+]o resulted in a 2- to 3-fold increase in [3H]SM compared to only a small increase in [3H]PC over the same period. There was a reciprocal relationship between [3H]ceramide and [3H]1,2-DAG levels with highest [3H]ceramide and lowest [3H]-1,2-DAG levels seen at lowest [Mg2+]o. The results indicate that a fall in extracellular ionized Mg2+ concentration produces a rapid and sustained decrease in membrane sphingomyelin and a moderate rise in intracellular ceramide. A major effect of lowering [Mg2+]o appears to be a down-regulation of SM synthase. The increased membrane SM content and a concomitant decrease in cell ceramide, in the presence of elevated [Mg2+]o, may be relevant to the apparent protective role of adequate Mg intake on vascular function in humans.

Utilizing the C-terminal cleavage activity of a protein splicing element to purify recombinant proteins in a single chromatographic step

A conventional affinity protein purification system often requires a separate protease to separate the target protein from the affinity tag. This paper describes a unique protein purification system in which the target protein is fused to the C-terminus of a modified protein splicing element (intein). A small affinity tag is inserted in a loop region of the endonuclease domain of the intein to allow affinity purification. Specific mutations at the C-terminal splice junction of the intein allow controllable C-terminal peptide bond cleavage. The cleavage is triggered by addition of thiols such as dithiothreitol or free cysteine, resulting in elution of the target protein while the affinity-tagged intein remains immobilized on the affinity column. This system eliminates the need for a separate protease and allows purification of a target protein without the N-terminal methionine. We have constructed general cloning vectors and demonstrated single-column purification of several proteins. In addition, we discuss several factors that may affect the C-terminal peptide bond cleavage activity.

Analysis of mechanisms and frequency of CDKN2A/B gene loss during progression of RAS-transformed rat embryo fibroblast clones

Rat embryo fibroblasts (REFs) are inefficiently transformed by RAS-oncogenes. Induction of p16INK4A expression by RAS has been suggested to contribute to this resistance. Glucocorticoid hormones, (DEX), enhance REF transformation by RAS and facilitates the isolation of transformed and immortal cell lines. We show that DEX induced cell proliferation is paralleled by a decrease in Cdkn2a gene transcripts, suggesting a mechanism for hormone promotion. The mechanisms of progression into hormone independent cell lines were examined. Twenty-two of 30 clones which reached a population size of approximately 10(6) cells could be established as cell lines. All lines studied showed homozygous deletions of the Cdkn2 loci (Cdkn2a and Cdkn2b) on RNO5. LOH was found for all RNO5 genetic markers examined in 7 of 19 cell lines, suggesting non-disjunction events. In the remaining 12 cell lines, both copies of Cdkn2 appeared to be lost by deletions/rearrangements, some of which could by demonstrated by karyotype analysis. We conclude that (i) clonal expansion of RAS-transfected REF by DEX is paralleled by down-regulation of Cdkn2a expression; (ii) homozygous deletion of Cdkn2 were estimated to occur at a frequency of 2 x 10(-8)/cell/generation or higher, and (iii) deletion/rearrangements and nondisjunction appear to be the main mechanisms leading to deletion of Cdkn2.

The Escherichia coli OxyS regulatory RNA represses fhlA translation by blocking ribosome binding

OxyS is a small untranslated RNA which is induced in response to oxidative stress in Escherichia coli. This novel RNA acts as a global regulator to activate or repress the expression of as many as 40 genes, including the fhlA-encoded transcriptional activator and the rpoS-encoded sigma(s) subunit of RNA polymerase. Deletion analysis of OxyS showed that different domains of the small RNA are required for the regulation of fhlA and rpoS. We examined the mechanism of OxyS repression of fhlA and found that the OxyS RNA inhibits fhlA translation by pairing with a short sequence overlapping the Shine-Dalgarno sequence, thereby blocking ribosome binding/translation.

The OxyS regulatory RNA represses rpoS translation and binds the Hfq (HF-I) protein

The OxyS regulatory RNA integrates the adaptive response to hydrogen peroxide with other cellular stress responses and protects against DNA damage. Among the OxyS targets is the rpoS-encoded sigma(s) subunit of RNA polymerase. Sigma(s) is a central regulator of genes induced by osmotic stress, starvation and entry into stationary phase. We examined the mechanism whereby OxyS represses rpoS expression and found that the OxyS RNA inhibits translation of the rpoS message. This repression is dependent on the hfq-encoded RNA-binding protein (also denoted host factor I, HF-I). Co-immunoprecipitation and gel mobility shift experiments revealed that the OxyS RNA binds Hfq, suggesting that OxyS represses rpoS translation by altering Hfq activity.

[PCR in combination with silver as a method for the determination of apolipoprotein E alleles]

OBJECTIVE

To present a rapid, sensitive and safe procedure for the determination of human apolipoprotein E alleles.

METHODS

Genomic DNA was extracted from 0.5ml whole blood by a non-phenol protocol. After PCR and restriction enzyme digestion,short DNA fragments were detected by a simplified silver staining method. This technique was used to assay apolipoprotein E alleles in 19 patients with sporadic Alzheimer's disease and 41 normal aged persons.

RESULTS

The short DNA fragments were visualized clearly on polyacrylamide gel processed by silver staining. It took 24 hours from DNA extraction to the final result. The A4 allele frequency in patients with sporadic Alzheimer's disease was 0.29, much higher than that in control group (0.02, P<0.001).

CONCLUSION

PCR in combination with silver staining can satisfy the need for high-resolution and high-efficiency in the determination of apolipoprotein E alleles and can be used as a routine procedure in clinical and epidemiological investigations.