Transcriptional regulation of human transcription factor IIB in SMMC-7721 human hepatocellular carcinoma cells by all-trans-retinoic acid and phorbol 12-myristate 13-acetate

The differential-display reverse transcription/polymerase chain reaction (DDRT-PCR) method was utilised to find genes differentially expressed at the messenger RNA level in SMMC-7721 human hepatocellular carcinoma cells treated and not treated with all-trans-retinoic acid, a differentiation inducer of the cell. Human transcription factor IIB (TFIIB) was discovered to be decreased on the 3rd day after the cells had been treated with retinoic acid and increased by phorbol 12-myristate 13-acetate, which stimulated the proliferation of human hepatocellular carcinoma cells. It was also found that the transcription of TFIIB in SMMC-7721 cell had no relationship to the cell cycle.

Differential apoptotic behaviors of c-myc, N-myc, and L-myc oncoproteins

c-, N-, and L-myc are related nuclear oncoproteins that bind similar DNA sites and cooperate with activated ras oncogenes to transform primary fibroblasts. Although c-myc can also promote apoptosis in some cells after growth factor withdrawal or exposure to cytotoxic agents, roles for N- and L-myc in apoptosis remain undetermined. To address this, c-, N-, or L-myc were stably expressed in the interleukin 3 (IL-3)-dependent 32D hematopoietic cell line. The apoptotic response of each cell line was assessed after IL-3 withdrawal or treatment with four structurally unrelated cytotoxic agents. All three oncoproteins accelerated apoptosis after IL-3 withdrawal. In contrast, whereas c-myc overexpression generally sensitized cells to cytotoxic drugs, N-myc and L-myc overexpression produced resistance. myc expression tended to be associated with a more robust G2-M arrest after drug exposure, but this did not correlate with drug sensitivity or resistance. Bcl-2 and Bcl-X(L) protected control cells against apoptosis after either IL-3 withdrawal or drug exposure, although in some cases this effect could be overridden by myc oncoproteins, particularly N-myc and L-myc. Our results suggest that the apoptotic pathways activated upon IL-3 withdrawal and cytotoxic drug treatment are distinct and differentially affected by members of the myc and Bcl-2 families.

[Dynamic change of androgen-receptor in tumor and surrounding liver tissue of nude mice model with transplanted human HCC]

OBJECTIVE

To research into the law of androgen-receptor (AR) dynamic change in developing course of human HCC.

METHOD

Dynamic measurement of AR in tumor and peritumorous tissue was performed in nude mice model with orthotopic transplanted human HCC.

RESULT

Tumor nodules were present in 90% nude mice 4 weeks after transplantation, tumor necrosis was found in the 10th week, and remarkable necrosis occurred in the 12th week. The quantity of AR in tumor and peritumorous tissue was highest in the early stage of tumor (102.32 +/- 21.42 fmol/mg protein and 72.45 +/- 10.11 fmol/mg protein respectively), and then decreased progressively with time to the 10th week (40.98 +/- 21.11 fmol/mg protein and 53.39 +/- 7.01 fmol/mg protein respectively). The difference in AR between each two weeks was significant.

CONCLUSION

Androgen promotes the development of tumor because of existence of AR, and its action may decline after establishment of tumor. Therefore, antiandrogen treatment may be ineffective after establishment of tumor.

Commonly occurring loss and mutation of the MXI1 gene in prostate cancer

One of the most common chromosomal abnormalities in prostate cancer involves loss of 10q22-qter. Rarely, a smaller deletion, involving 10q24-q25, has been observed, suggesting the presence of a tumor suppressor gene at this site. We previously demonstrated that the MXI1 gene maps to 10q24-q25 and is mutated in some tumors with cytogenetically detectable deletions of this locus. MXI1 encodes a basic-helix-loop-helix protein that suppresses the transcriptional activity of the MYC oncoprotein by competing for the common dimerization partner, MAX, and binding to identical DNA sites. Because more than 90% of prostate tumors contain no cytogenetic abnormality of 10q, the relevance of MXI1 loss and/or mutation to the vast majority of cases remains unclear. We prospectively evaluated prostate tumors for loss of MXI1 by fluorescence in situ hybridization (FISH) and cytogenetic techniques. Twenty-one of 40 tumors (53%) demonstrated loss of a single MXI1 allele as determined by FISH. Ten cases with cytogenetically normal 10qs, but with FISH-documented deletion of MXI1, were examined at the molecular level, and eight mutations were identified, albeit at low frequency. Five of the mutant proteins were unable to bind DNA in association with MAX. We conclude that MXI1 gene loss in prostate cancer is common and most frequently involves a cytogenetically undetectable deletion.

Prion protein expression in different species: analysis with a panel of new mAbs

By immunizing prion knockout mice (Prnp-/-) with recombinant murine prion protein (PrPc), we obtained a panel of mAbs specific for murine PrPc. These mAbs can be applied to immunoblotting, cell surface immunofluorescent staining, and immunohistochemistry at light and electron microscopy. These mAbs recognize both the normal (PrPc) and protease-resistant (PrPres) isoforms of PrP. Some mAbs are species restricted, while others react with PrP from a broad range of mammals including mice, humans, monkeys, cows, sheep, squirrels, and hamsters. Moreover, some of the mAbs selectively recognize different PrP glycoforms as well as the metabolic fragments of PrPc. These newly generated PrPc antibodies will help to explore the biology of PrPc and to establish the diagnosis of prion diseases in both humans and animals.

Induction of antioxidants by adriamycin in mouse heart

Cardiac oxidative injury is a major limiting factor for clinical application of Adriamycin (ADR) in cancer chemotherapy. ADR depresses some antioxidant systems, thereby further enhancing the cardiotoxicity. Previous studies have shown that ADR inhibits the overall synthesis of DNA, RNA, and protein. It was presumed that the depressed antioxidant activity resulted from the inhibited gene expression. However, there were no experimental data to demonstrate the relationship between the change in antioxidant activities and that in their gene expression. Therefore, the present study was undertaken to examine the effects of ADR on the activities and mRNA abundances of antioxidants in mouse heart. FVB mice (7 weeks old) were treated with ADR (15 mg/kg) by a single i.p. injection. Four days after the treatment, cardiac antioxidant activities and mRNA abundances were measured. The results showed that ADR increased the levels of mRNAs for Cu,Zn-superoxide dismutase (Cu,Zn-SOD), catalase, glutathione peroxidase (GSHpx), and gamma-glutamylcysteine synthetase (gamma-GCS). On the other hand, ADR increased the activities of catalase and gamma-GCS, and slightly decreased total glutathione concentrations in the heart. Cu,Zn-superoxide dismutase, Mn-superoxide dismutase, and glutathione peroxidase activities were not changed significantly. In addition, ADR increased both mRNA and protein levels of metallothionein in the heart. The data demonstrate that up-regulation of antioxidant gene expression occurred in response to ADR in the mouse heart, although the antioxidant activities were not all increased.

[The effect of recombinant tissue inhibitor of metalloproteinase-3 (TIMP-3) on tumor growth and metastases]

OBJECTIVE

To investigate the anti-cancer effect of tissue inhibitor of metalloproteinase-3 (TIMP-3) and its mechanism of action.

METHODS

Recombinant TIMP-3(rTIMP-3) was prepared and used to study its effect on tumor growth and metastases in mice, and its effect on angiogenesis in chicken embryo allantoic membrane (CAM).

RESULTS

rTIMP-3 was able to inhibit growth of subcutaneously implanted S180 sarcoma and hepatic carcinoma H22 in a dose-dependent manner. When the rTIMP-3 was given i.p. at a daily dose of 20 mg/kg body weight for 10 days, the growth of S180 sarcoma and H22 carcinoma was inhibited by 63.2% and 73.4%, respectively. The metastases of i.v. injected Lewis lung carcinoma(3LLC) was also suppressed by rTIMP-3, with an inhibition rate of 59.8%. rTIMP-3 was found to significantly inhibit angiogenesis in CAM assay.

CONCLUSION

rTIMP-3 has anti-cancer activity, and the mechanism of action might be associated with its inhibition on extracellular matrix degradation and anti-angiogenesis.

Lack of transcriptional repression by max homodimers

Max, a basic-helix-loop-helix-leucine zipper (bHLH-ZIP) protein, plays a central role in the transcriptional regulation of myc oncoprotein-responsive genes. Myc-max heterodimers bind to consensus E-box motifs near or within the promoters of these genes and activate gene expression, whereas heterodimers between max and members of the mad family of bHLH-ZIP proteins promote transcriptional repression. In contrast to all other members of the myc network, max readily homodimerizes and binds to identical E-box sites in vitro. However, the role for max homodimers in transcriptional repression in vivo is unclear. Upstream stimulatory factor (USF) is a bHLH-ZIP protein which does not interact with members of the myc-max-mad family. By replacing the HLH-ZIP domain of max with that from USF, we created a chimeric protein, max(USF), which was indistinguishable from max with respect to its ability to homodimerize and bind DNA. As expected, however, max(USF) was unable to heterodimerize with any of the tested max partner proteins and was incapable of suppressing c-myc target genes. Thus, transcriptional repression is an exclusive property of max-mad heterodimers and cannot be achieved by max homodimers alone.

[Hepatectomy for hepatolithiasis treatment of 354 cases]

OBJECTIVE

To evaluate the effect of hepatectomy for hepatolithiasis.

METHOD

354 patients with hepatolithiasis underwent hepatectomy in the past 10 years. The results were analysed retrospectively, including clinical findings, distribution of stones, patterns of operation, postoperative complications, and residual stones. The clinical data of the patients before 1990 were compared with those thereafter.

RESULT

Left hepatolithiasis was the most common form (323 patients). Left lateral lobectomy and left hepatectomy were most commonly employed (91.2%). 166 of the patients underwent concurrent cholangiojejunostomy. 13.8% patients had residual stones, and postoperative complications occurred in 60 patients, including 4 deaths. Few patients were reoperated on and the incidence of residual stones was lower after 1990. 88% the patients showed excellent or good result.

CONCLUSION

Hepatectomy is a procedure for the management of hepatolithiasis, but still requires combined plasty of stenotic intrahepatic bile ducts and cholangiojejunostomy to reduce the incidence of residual stones and recurrence.

Myelin-associated glycoprotein is a myelin signal that modulates the caliber of myelinated axons

Myelination increases neuronal conduction velocity through its insulating properties and an unidentified extrinsic effect that increases axonal caliber. Although it is well established that demyelination can cause axonal atrophy, the myelin molecule that regulates axonal caliber is not known. Loss of the structural proteins of compact peripheral nervous system (PNS) myelin, P0 protein, and myelin basic protein does not lead to axonal atrophy. This study demonstrates that mice with a null mutation of the myelin-associated glycoprotein (MAG) gene have a chronic atrophy of myelinated PNS axons that results in paranodal myelin tomaculi and axonal degeneration. Absence of MAG was correlated with reduced axonal calibers, decreased neurofilament spacing, and reduced neurofilament phosphorylation. Because axonal atrophy and degeneration in MAG-deficient mice occur in the absence of inflammation, hypomyelination, significant demyelination-remyelination, or gain of function mutations, these data support a functional role for MAG in modulating the maturation and viability of myelinated axons.

Mmip1: a novel leucine zipper protein that reverses the suppressive effects of Mad family members on c-myc

C-myc, a member of the basic helix-loop-helix-leucine zipper (bHLH-ZIP) protein family activates target genes in heterodimeric association with another bHLH-ZIP protein, Max. Max readily homodimerizes, competes with C-myc-Max heterodimers, and represses transcription. Four additional bHLH-ZIP proteins, Mad1, Mxi1, Mad3 and Mad4, heterodimerize with Max and also repress transcription of c-myc-responsive genes. We employed a yeast two-hybid approach to identify proteins which interact with Mxi. We identified a novel ZIP-containing protein, Mmip1 (Mad member-interacting protein 1) that strongly dimerizes with all four Mad members, but not with c-myc, Max, or with unrelated HLH proteins. The Mmip1-Mxi association is mediated by the ZIP domain of each polypeptide and is as strong or stronger than the associations between c-myc and Max or Max and Mxi1. In vitro, Mmip1 can inhibit DNA binding by Max-Mad heterodimers and, in vivo, can reverse the suppressive effects of Mad proteins on c-myc functions. Mmipl is found in a variety of cells types, is induced by serum stimulation, and can be co-immunoprecipitated from fibroblasts in association with Mxi1. By interfering with the dimerization between Max and Mad family member proteins, Mmip1 can indirectly up-regulate the transcriptional activity of c-myc and suppress the antiproliferative actions of Mad proteins.

Erythroid 5-aminolevulinate synthase is required for erythroid differentiation in mouse embryonic stem cells

We have examined the induction of the enzymes of the heme biosynthetic pathway during erythroid differentiation of mouse embryonic stem (ES) cells. Following transfer to appropriate medium all of the pathway enzymes are induced within three days. Unlike differentiating mouse erythroleukemia cells (Lake-Bullock, H. and Dailey, H.A. Mol Cell Biol 13:7122-7132, 1993), all of the enzymes appear to be induced simultaneously and not sequentially in differentiating ES cells. The role of erythroid 5-aminolevulinate synthase (ALAS-2) in this differentiation process was examined by disruption of the ALAS-2 gene. The targeting vector used for disruption replaced all of exons 4 to 6 with a selectable neomycin resistance gene. The resulting genetically modified (ALAS-2 knockout) cells, as well as normal ES cells were used to study induction of heme biosynthesis. Following 10 days of culture in methylcellulose media significant morphological differences between the embryoid bodies (EBs) of the two cell lines were observed. ES cells exhibited morphology of typical EBs with a dark field (blood island) in the center, while ALAS-2 knockout ES cells developed very poorly both in size and shape. At 8 days of differentiation, only 3% of all EBs contained visible erythropoietic cells (i.e., stained positively for hemoglobin) in the ALAS-2 knockout cell line, compared with 50% in ES cells. Most of the genes in the heme synthetic pathway were expressed to a stable level within 3 to 6 days after induction in normal ES cells, while the ALAS-2 knockout cell line failed to significantly increase the level of expression of these genes. Fetal beta-globin mRNA was not detectable in the differentiating ALAS-2 knockout cells, whereas mRNA for this gene was detected in normal ES cells within 3 days of differentiation. These results suggest that ALAS-2 is necessary for ES cell erythroid differentiation and that there is an interrelationship between heme and globin synthesis in differentiating ES cells.

[The analysis of fatty acid composition in syncytiotrophoblast plasma membranes of human placenta]

The fatty acids were determined in syncytiotrophoblast plasma membranes of the eighteen human placenta from the normal pregnant women. With the method of Landon, the fat was purified in syncytiotrophoblast plasma membranes, which was extracted from the placenta by using the procedure of Whitsett. The methylated fatty acids were separated with gas chromatography in which a glass column packed with DEGS was used. In comparing the retention time of the sample with the standards and referring to the results of GC/MS, thirteen peaks were identified and quantified. The area normalization method was used to determine the distribution, the compositions and contents of fatty acids in syncytiotrophoblast plasma membranes. It is shown that the amount of identified fatty acids attains 74.1% of total peak area, in which the amount of saturated fatty acids was 30.64%, and the unsaturated was 43.46%.

[Light microscopic observation of bone interface of titanium-coated 317L plate screw]

The observational results of bone interface of titanium-coated 317L plate screw and 317L plate screw under light microscope are reported in the present paper. Osseointegration was formed in both kinds of screws after implanting. In the titanium-coated 317L plate screw group, the inflammatory reaction was slighter, the new bone formed earlier in the interface and the bone was combined with the metal tightly, whereas in the uncoated 317L plate screw group, the relationship between the bone and metal was only a state of contact. These indicate that the bone interface and tissue compatibility of titanium-coated 317L plate screw may be better than that of the 317L plate screw.

Chinese dietary composition and intakes of elements and radionuclides by ingestion

As update and complement of Chinese Total Diet Study in 1990, a renewing study was conducted during 1992-1993 according to regulated procedure. Contents of 32 elements, including 19 newly determined, in 12 categories of food from 12 provinces were analyzed by NAA or AAS technique and the daily intakes of Chinese adult man were estimated and hygienically evaluated. Meanwhile, a typical survey on dietary composition and intake for difference among 4 age groups and between Spring and Autumn was surveyed too. The results provide important basis for decision for further improvement of Chinese diet from hygienic view point and compilation of physiological characteristics of Chinese Reference Man. At the end of this article, the estimated nationwide average intakes for adult man are compared with those for current ICRP Reference Man.

Mu opioid receptor phosphorylation, desensitization, and ligand efficacy

Mu opioid receptors are subject to phosphorylation and desensitization through actions of at least two distinct biochemical pathways: agonist-dependent mu receptor phosphorylation and desensitization induced by a biochemically distinct second pathway dependent on protein kinase C activation (1). To better understand the nature of the agonist-induced mu receptor phosphorylation events, we have investigated the effects of a variety of opiate ligands of varying potencies and intrinsic activities on mu receptor phosphorylation and desensitization. Exposure to the potent full agonists sufentanil, dihydroetorphine, etorphine, etonitazine, and [D-Ala2, MePhe4, Glyol5]enkephalin (DAMGO) led to strong receptor phosphorylation, while methadone, l-alpha-acetylmethadone (LAAM), morphine, meperidine, DADL, beta-endorphin(1-31), enkephalins, and dynorphin A(1-17) produced intermediate effects. The partial agonist buprenorphine minimally enhanced receptor phosphorylation while antagonists failed to alter phosphorylation. Buprenorphine and full antagonists each antagonized the enhanced mu receptor phosphorylation induced by morphine or DAMGO. The rank order of opiate ligand efficacies in producing mu receptor-mediated functional desensitization generally paralleled their rank order of efficacies in producing receptor phosphorylation. Interestingly, the desensitization and phosphorylation mediated by methadone and LAAM were disproportionate to their efficacies in two distinct test systems. This generally good fit between the efficacies of opiates in mu receptor activation, phosphorylation, and desensitization supports the idea that activated receptor/agonist/G-protein complexes and/or receptor conformational changes induced by agonists are required for agonist-induced mu receptor phosphorylation. Data for methadone and LAAM suggest possible contribution from their enhanced desensitizing abilities to their therapeutic efficacies.

CNP overexpression induces aberrant oligodendrocyte membranes and inhibits MBP accumulation and myelin compaction

2',3'-Cyclic nucleotide 3'-phosphodiesterase (CNP) is highly enriched in myelin-forming cells where it is concentrated at the cytoplasmic side of all surface membranes except those of compact myelin. Previous studies have provided evidence that CNP is functionally involved in migration or expansion of membranes during myelination. This hypothesis is supported, in part, by the production of aberrant myelin membranes in transgenic mice that have a 6-fold increase in CNP expression. In addition, many myelin lamellae in these CNP-overexpressing mice lacked major dense lines (MDLs). The purpose of the present study was to determine if CNP overexpression altered: (1) oligodendrocyte and myelin membrane production during early stages of myelination, and (2) the ultrastructural distribution of CNP and myelin basic protein (MBP) in myelin membranes. We identified aberrant membrane expanses that extended from premyelinating oligodendrocyte processes, the periaxonal membrane, and the contact point between oligodendrocyte processes and myelin internodes. Myelin membranes without MDLs were deficient in MBP and enriched in CNP. These data support a functional role for CNP during oligodendrocyte membrane expansion and indicate, for the first time, that CNP may help target MBP to compact myelin.

Expression of preproopiomelanocortin mRNA and preprodynorphin mRNA in brain of spontaneously hypertensive rats

AIM

To compare the expressions of prepropiomelanocortin (POMC) mRNA and preprodynorphin (PPD) mRNA between 16-wk-old spontaneously hypertensive rats (SHR) and age-matched normotensive Wistar-Kyoto rats (WKY).

METHODS

The expression of POMC mRNA and PPD mRNA were detected with nonradioactive in situ hybridization by digoxigenin-labeled RNA probe.

RESULTS

POMC mRNA mainly was expressed in arcuate nucleus, compared with WKY, SHR had higher level of POMC mRNA (542). PPD mRNA was found in hippocampus, hypothalamus, central gray, nucleus of the solitary tract (NTS), and thoracic spinal cord (T4-T6). Compared with WKY, PPD mRNA level of SHR decreased in dentate gyrus (2342), NTS (381), and medial preoptic area (467); no difference was observed in arcuate nucleus (263), thoracic spinal cord (750-1800) and CA1, CA2, CA3 of hippocampus (1674, 2014, 2626).

CONCLUSION

Increase of POMC mRNA in arcuate nucleus and decrease of PPD mRNA in dentate gyrus of SHR may be associated with the genesis of spontaneous hypertension.

Differential interactions of Id proteins with basic-helix-loop-helix transcription factors

Dimerization of three Id proteins (Id1, Id2, and Id3) with the four class A E proteins (E12, E47, E2-2, and HEB) and two groups of class B proteins, the myogenic regulatory factors (MRFs: MyoD, myogenin, Myf-5 and MRF4/Myf-6), and the hematopoietic factors (Scl/Tal-1, Tal-2, and Lyl-1) were tested in a quantitative yeast 2-hybrid assay. All three Ids bound with high affinity to E proteins, but a much broader range of interactions was observed between Ids and the class B factors. Id1 and Id2 interacted strongly with MyoD and Myf-5 and weakly with myogenin and MRF4/Myf-6, whereas Id3 interacted weakly with all four MRFs. Similar specificities were observed in co-immunoprecipitation and mammalian 2-hybrid analyses. No interactions were found between the Ids and any of the hematopoietic factors. Each Id was able to disrupt the ability of E protein-MyoD complexes to transactivate from a muscle creatine kinase reporter construct in vivo. Finally, mutagenesis experiments showed that the differences between Id1 and Id3 binding map to three amino acids in the first helix and to a small cluster of upstream residues. The Id proteins thus display a signature range of interactions with all of their potential dimerization partners and may play a role in myogenesis which is distinct from that in hematopoiesis.

Novel regulation of the helix-loop-helix protein Id1 by S5a, a subunit of the 26 S proteasome

Id proteins negatively regulate the dimerization, DNA binding, and biological properties of basic helix-loop-helix proteins. In a search for novel factors that interact with Id1, we identified a component of the 26 S proteasome, S5a, that has previously been implicated only in the recognition of ubiquitinated polypeptides destined for proteolysis. S5a interacts strongly with Id1, less strongly with the basic helix-loop-helix proteins MyoD and E12, and not at all with other Id proteins. S5a restores DNA binding by MyoD-Id1 and E12-Id1 heterodimers, enhances DNA binding by MyoD and E12 homodimers, and reverses Id1-mediated repression of the muscle creatine kinase promoter during myogenic differentiation. Mutagenesis experiments showed that amino acids flanking the helix-loop-helix domain plus three residues in the first helix of Id1 impart S5a recognition. This requires only the NH2-terminal half of S5a. S5a thus appears to promote the positive regulation of myogenic genes through ubiquitin-independent mechanisms involving inhibition of Id1 and the enhancement of DNA binding by MyoD and E12. This latter property may permit the selection of novel promoter binding sites during myogenesis.

Analytical derivatizations of volatile and hydrophilic carbonyls from aqueous matrix onto a solid phase of a polystyrene-divinylbenzene macroreticular resin

Extraction and derivatization of carbonyls to benzyloximes, pentafluorobenzyloximes or 2,4-dinitrophenylhydrazones is simplified and reaction times are substantially reduced by simultaneous sorption and derivatization from aqueous solution onto a solid phase. In this reaction a macroreticular polystyrene-divinylbenzene resin acts as a sorbent and catalyst to allow simultaneous extraction and derivatization of hydrophilic and lipophilic aldehydes and ketones from simple as well as complex matrices including plasma. Conversion to the 2,4-dinitrophenylhydrazones or pentafluorobenzyloximation at ambient temperature requires 10 and 20 min, respectively. These reaction conditions correspond to at least a 6-fold reduction in reaction times for derivatization of the reactive aldelhydes and a 36-72-fold reduction for preparation of derivatives for the slower reacting ketones.

A simple method for enumerating bacteriophages in soil

A plaque technique that uses antibiotic-resistant bacteria growing on antibiotic-containing agar for the assay lawn resulted in significantly better recovery of bacteriophages P1 of Escherichia coli and F116 of Pseudomonas aeruginosa from nonsterile soil than standard membrane filtration or centrifugation techniques. Adsorption of the phages on soil particles appeared to be involved in their recovery and survival in soil.

[Clinical observation of TMJDS treated with pivot splint]

The pivot splint was applied to 50 patients with temporomandibular joint dysfunction syndrome that included 30 patients of anterior disc displacement without reduction, 12 patients of anteriordisc displacement with partial reduction and 8 patients of upward condyle displacement. The mouth opening and joint space of the TMJ tomographies before and after treatment were measured for each case. The results indicated that treatment with pivot splint was very effective for the patients with downward diplacemenr of the condyle. As a result, among 50 patients, 36 patients were cured (72%) and 14 patients were improved (28%). The results of 3 years follow-up indicated that original symptoms of the patients had no recurrence.

Differential determination of arsenic (III) and total arsenic with L-cysteine as prereductant using a flow injection non-dispersive atomic absorption device

Speciation of arsenic in environmental samples gains increasingly importance, as the toxic effects of arsenic are related to its oxidation state. A method was developed for the determination of trace amounts of arsenic (III) and total arsenic by flow injection hydride generation coupled with an in-house made non-dispersive AAS device. The total arsenic is determined after prereduction of arsenic (V) to arsenic (III) with L-cysteine in a low concentration of hydrochloric, acetic or nitric acid. The conditions for the prereduction, hydride generation and atomization were systematically investigated. A quartz tube temperature of 800 degrees C was found to be optimum in view of peak shape and baseline stability. Pb(II), Ni(II), Fe(III), Cu(II), Ag(I), Al(III), Ga(II), Se(IV), Bi(III) were checked for interfering with the 2 microg/L As(V) signal. A serious signal depression was only observed for Se(IV) and Bi(III) at a 150-fold excess. With the above system, arsenic was determined at a sampling frequency of about 1/min with a detection limit (3sigma) of 0.01 microg/L using a 0.5 mL sample. The reagent blank was 0.001+/-0.0003 absorbance units and the standard deviation of 10 measurements of the 2 microg/l As signal was found to be 1.2%. Results obtained for standard reference materials and water samples are in good agreement with the certified values and those obtained by ICP-MS

Molecular pathogenesis of peripheral neuropathy

Peripheral neuropathies can result from a failure to form or maintain the myelin internode or from autoimmune-mediated demyelination. Several gene defects responsible for the most common inherited human peripheral neuropathies referred to as Charcot-Marie-Tooth disease have been reported. These studies identified PMP-22 and connexin-32 as proteins that are essentiel for normal myelination. Point mutations in Po protein, PMP-22, and connexin-32 have been identified as causes of inherited peripheral neuropathies. In addition, studies indicated for the first time that alterations in PMP-22 gene dosage (trisomy and monosomy) can induce inherited peripheral neuropathies. Little is known, however, about how these gene defects cause myelin pathology. This report describes the distributions of proteins within the peripheral myelin internode and discusses how these molecules contribute to the pathogenesis of inherited and autoimmune peripheral neuropathy. A better understanding of the molecular composition of the myelin internode is essential for diagnosis and treatment of human peripheral neuropathies.

Mapping of preproenkephalin mRNA in brain of spontaneously hypertensive rats

AIM

To detect different expression of preproenkephalin mRNA (PPE mRNA) in 16-wk-old spontaneously hypertensive rat (SHR) and age-matched normotensive Wistar-Kyoto rat (WKY).

METHODS

Nonradioactive in situ hybridization was performed using digoxigenin-labeled RNA probe.

RESULTS

Compared with WKY rats, PPE mRNA levels of 16-wk-old SHR increased in hypothalamic nuclei (> 20), amygdaloid nuclei (> 23), ventrolateral central gray (21.2), reticular substantia nigra (21.5), interpeduncular nuclei (> 21), nucleus of the solitary tract (30.7), rostroventrolateral reticular nucleus (29.1), gigantocellular reticular nucleus (23.9) and thoracic spinal cord (> 30); decreased in dorsal central gray (22.7). No difference was found in compact substantia nigra (22.8), dentate gyrus (26.2) and CA1, CA2, CA3 of hippocampus (> 25).

CONCLUSION

PPE mRNA in brain regions involved in modulation of blood pressure may be associated with the genesis of spontaneous hypertension in SHR. Enkephalin, an endogenous ligand of opioid receptors, is important in the regulation of blood pressure (BP). Intracerebroventricular injection (icv) of mu agonist [D-Ala2-MePhe4-Gly5-ol]-enkephalin (DAGO) and delta agonist [D-Ala2, D-Leu5]-enkephalin (DADLE) increased the BP[1]. In situ hybridization study showed preproenkephalin mRNA was localized in hypothalamic nuclei, hippocampus, NTS, and spinal cord[2], where the cardiovascular regulation took place. The icv of mu agonist morphiceptin induced a pressor response in SHR but hypotension in WKY rat, and delta agonist Tyr-D-Thr-Gly-Phe-Leu-Thr (DTLET) icv decreased BP in SHR but increased BP in WKY[3]. Compared with WKY rats, SHR had greater concentration of methionine-enkephalin (Met-Enk) in cortex, pons, and medulla[4], but lower Leu-Enk in suprachiasmatic nucleus[5]. These studies imply that opiate system is disturbed in essential hypertension. The aim of this study is to determine whether the biosynthetic activity of CNS opiates in brain is altered in case of essential hypertension.

[Methylene blue staining in fiberoptic bronchoscopy in the diagnosis of bronchial tumors]

47 patients were stained by using methylene blue in fiberoptic bronchoscopy. Of these, 35 had central lung cancer, and 12 bronchitis. 40 patients with central lung cancer were detected by general fibreoptic endoscopy. The results demonstrated that normal bronchial mucosa was not stained, 97.14% central malignant bronchial tumors stained, and 8.33% bronchitis stained. X2test showed the marked difference. Positive diagnosis was 97.06% in biopsy specimens stained, it was higher than 77.05% in the general investigated (P < 0.05). Using methylene blue in fiberoptic bronchoscopy would help diagnose central lung cancer, determine tumors limits, permit accurate biopsy. The stain was not related to the pathological classification, differentiation of cancer cells, and classification of clinical pathology (P > 0.05).

Identification of an arginine residue in the dual coenzyme-specific glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides that plays a key role in binding NADP+ but not NAD+

Glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides can utilize either NADP or NAD as coenzyme. The enzyme's three-dimensional structure has been solved (Rowland et al., 1994, Structure 2, 1073-1087) and shown to contain a conventional nucleotide binding domain. NADP+ was modeled into the structure by superimposing the beta alpha beta domain and that of coenzyme-bound 6-phosphogluconate dehydrogenase (Adams et al., 1994, Structure 2, 651-658), enabling us to identify Arg-46 as a potentially important residue for NADP+ binding. Using site-directed mutagenesis, we constructed mutant enzymes in which Arg-46 was replaced by glutamine (R46Q) and alanine (R46A) and examined their kinetic properties. The principal effects in these mutant enzymes were that the Km and Ki values for NADP+ increased by 2 to 3 orders of magnitude over those of the wild-type enzyme. No other kinetic constant was altered more than 6.5-fold. Changing this single amino acid leads to mutant glucose-6-phosphate dehydrogenases with coenzyme specificities that favor NAD+, whereas the wild-type enzyme prefers NADP+ as coenzyme. These results confirm that Arg-46 plays a key role in NADP+ binding by contributing a positively charged planar residue that interacts primarily with the 2'-adenosine phosphate. The Arg residue corresponding to Arg-46 in L. mesenteroides glucose-6-phosphate dehydrogenase is conserved in all glucose-6-phosphate dehydrogenases and, presumably, plays the same role in all these enzymes.

Identification of an arginine residue in the dual coenzyme-specific glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides that plays a key role in binding NADP+ but not NAD+

Glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides can utilize either NADP or NAD as coenzyme. The enzyme's three-dimensional structure has been solved (Rowland et al., 1994, Structure 2, 1073-1087) and shown to contain a conventional nucleotide binding domain. NADP+ was modeled into the structure by superimposing the beta alpha beta domain and that of coenzyme-bound 6-phosphogluconate dehydrogenase (Adams et al., 1994, Structure 2, 651-658), enabling us to identify Arg-46 as a potentially important residue for NADP+ binding. Using site-directed mutagenesis, we constructed mutant enzymes in which Arg-46 was replaced by glutamine (R46Q) and alanine (R46A) and examined their kinetic properties. The principal effects in these mutant enzymes were that the Km and Ki values for NADP+ increased by 2 to 3 orders of magnitude over those of the wild-type enzyme. No other kinetic constant was altered more than 6.5-fold. Changing this single amino acid leads to mutant glucose-6-phosphate dehydrogenases with coenzyme specificities that favor NAD+, whereas the wild-type enzyme prefers NADP+ as coenzyme. These results confirm that Arg-46 plays a key role in NADP+ binding by contributing a positively charged planar residue that interacts primarily with the 2'-adenosine phosphate. The Arg residue corresponding to Arg-46 in L. mesenteroides glucose-6-phosphate dehydrogenase is conserved in all glucose-6-phosphate dehydrogenases and, presumably, plays the same role in all these enzymes.

Distributions of mu and delta opioid receptors in central nervous system of SHR rats and normotensive WKY rats

AIM

To compare the distributions of opioid receptor subtypes in central nervous system of spontaneously hypertensive rat (SHR) and normotensive Wistar-Kyoto (WKY) rat.

METHODS

[3H] Ohmefentanyl (OMF), [3H]N-methyl-N-[7-(I-pyrrolidinyl)-1-oxaspiro (4,5)dec-8-yl] benzeneacetamide (U-69593) and [3H]etorphine after suppression of mu and kappa-sites by 15 mumol.L-1 each of unlabeled OMF and trans-(1R,2R)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl) cyclohexyl]-benzeneacetamide hydrochloride (U-50 488H) were used as ligands for mu, kappa, and delta opioid receptor subtypes in autoradiography, respectively.

RESULTS

Delta receptors had an increase in hypothalamic nuclei, periaqueductal gray, caudate and interpeduncular nuclei, and a decrease in substantia nigra in SHR than in those of WKY rat. Mu receptors were less concentrated in basolateral amygdaloid nucleus, habenular nuclei and nucleus of solitary tract of SHR than in those of WKY rats. Kappa receptor density was not checked out in the present study.

CONCLUSION

Distribution of opioid receptor subtypes is related to hypertension of SHR, and delta opioid receptor is more important than mu opioid receptor in the maintenance of hypertension in SHR.

Effect of polysialic acid on the behavior of retinal ganglion cell axons during growth into the optic tract and tectum

We have demonstrated previously that the polysialic acid (PSA) moiety of the neural cell adhesion molecule (NCAM) can regulate peripheral nerve branching during development. In particular, it was found that specific enzymatic removal of PSA from motor axons causes them to form tight fascicles that are less responsive to normal guidance cues. In the present study, the role of PSA in the behavior of axons in the central nervous system has been examined through an analysis of chick optic axons during development. Unlike peripheral axons, which generally grow in a PSA-free environment, PSA was found to be present both on retinal ganglion cell axons and their environment in the tract and tectum. Furthermore, the enzymatic removal of PSA from the optic axons caused them to defasciculate in the tract/tectal region. This response was morphologically similar to targeting corrections made by these axons at a later stage when PSA levels have decreased, suggesting that the PSA may serve to shield them from responding prematurely to some guidance cues in their target region.

Different distributions of opioid receptors in spontaneously hypertensive rats and Wistar-Kyoto rats

AIM

To compare the densities of opioid receptors in spontaneously hypertensive rats (SHR) with those of normotensive Wistar-Kyoto (WKY) rats in central nervous system which are related to the regulation of BP.

METHODS

[3H] Etorphine, a nonspecific opioid ligand, was used to determine the distributions of opioid receptors in 16-wk-old SHR and WKY rats by quantitative autoradiography.

RESULTS

The densities of [3H]etorphine in hippocampus (P < 0.01), periaqueductal gray, nucleus of the solitary tract, and thoracic (T4-6) spinal cord (P < 0.05) of SHR were lower than those of WKY rats. But in basolateral amygdaloid nucleus (P < 0.01), habenular nuclei (P < 0.05), and hypothalamic nuclei including arcuate nucleus (P < 0.01), higher densities of opioid receptors were found in SHR. No difference existed in interpeduncular nuclei between the 2 groups.

CONCLUSION

The difference in distributions of opioid receptors is related to the hypertension in SHR.

Mutation of the MXI1 gene in prostate cancer

The Mxi1 protein negatively regulates Myc oncoprotein activity and thus potentially serves a tumour suppressor function. MXI1 maps to chromosome 10q24-q25, a region that is deleted in some cases of prostate cancer. We have detected mutations in the retained MXI1 alleles in four primary prostate tumours with 10q24-q25 deletions. Two tumours contained inactivating mutations, whereas two others contained the identical missense mutation. Fluorescence in situ hybridization also demonstrated loss of one MXI1 allele in an additional tumour lacking chromosome 10 abnormalities. MXI1 thus displays allelic loss and mutation in some cases of prostate cancer that may contribute to the pathogenesis or neoplastic evolution of this common malignancy.

Phencyclidine receptors in brain and spinal cord of spontaneously hypertensive rats aged 4-16 wk

AIM

To study the relationship between the density of phencyclidine [1-(1-phenylcyclohexyl)piperidine hydrochloride, Phe] receptor binding sites in brain and thoracic spinal cord (T4-6) and the development of hypertension in spontaneously hypertensive rat (SHR).

METHODS

The density of Phe binding sites was determined by autoradiography using [3H]Phe in 4-, 8-, 12- and 16-wk-old rats.

RESULTS

There were fewer Phe binding sites in the hippocampus and dorsal horn of thoracic spinal cord of SHR at 12 and 16 wk (P < 0.01), when hypertension has established; while at 4 wk of age, before the development of hypertension, more Phe binding sites were found in SHR. As blood pressure began to rise at 8 wk, SHR had more Phe binding sites in hippocampus vs WKY, but no difference was seen between 2 strains in the dorsal horn of thoracic spinal cord.

CONCLUSION

Phe receptors might be involved in the genesis of SHR hypertension.

The effect of radix Salviae Miltiorrhizae Composita on peroxidation of low density lipoprotein due to copper dichloride

It is well known that plasma lipoprotein, particularly oxidized LDL, plays an important role in the pathogenesis of atherosclerosis and atherosclerotic diseases. We used oxidized LDL generated by incubating LDL from healthy persons with copper dichloride as a model to investigate the antioxidate property of Radix Salviae Miltiorrhizae Composita (RSMC). On photos, the spot X1 and the spot X2 were clearly found in the control group after the dialysis into copper dichloride for 24 and 48 hours, but they could not found in the RSMC group. The analysis of the constituents of lipids in LDL (by charring method) showed that after dialysis the percentages of the spot X1 and the spot X2 in the RSMC group were significantly lower than those in the control group (P < 0.01). The results suggest that RSMC plays a potential role in antioxidation of lipids or LDL.

Assignment of the human MAD and MXI1 genes to chromosomes 2p12-p13 and 10q24-q25

MAD and MXI1, two recently described members of the basic helix-loop-helix (bHLH) gene family, encode proteins that dimerize with and modulate the DNA binding of max. In turn, mad-max or mxi1-max heterodimers or max homodimers can compete for DNA binding sites with dimers formed between max and myc oncoproteins and antagonize the transcriptional activities of this latter class of proteins. Using a combination of somatic cell mapping and fluorescence in situ hybridization techniques, we have determined the chromosomal locations of the MAD and MXI1 genes. The MAD gene maps to chromosome 2p12-p13, a region involved in translocations and deletions in acute and chronic lymphocytic leukemias as well as non-lymphocytic leukemias and Hodgkin disease. The MXI1 gene localizes to chromosome 10q24-q25, a region involved in translocations and deletions in acute and chronic lymphocytic leukemias and prostatic carcinomas. The availability of genomic clones of MAD and MXI1 will permit an assessment of their involvement in these diseases at the molecular level.

Target determination of neurotransmitter phenotype in sympathetic neurons

While the majority of sympathetic neurons are noradrenergic, a minority population are cholinergic. At least one population of cholinergic sympathetic neurons arises during development by a target-dependent conversion from an initial noradrenergic phenotype. Evidence for retrograde specification has been obtained from transplantation studies in which sympathetic neurons that normally express a noradrenergic phenotype throughout life were induced to innervate sweat glands, a target normally innervated by cholinergic sympathetic neurons. This was accomplished by transplanting footpad skin containing sweat gland primordia from early postnatal donor rats to the hairy skin region of host rats. The sympathetic neurons innervating the novel target decreased their expression of noradrenergic traits and developed choline acetyltransferase (ChAT) activity. In addition, many sweat gland-associated fibers acquired acetylcholinesterase (AChE) staining and VIP immunoreactivity. These studies indicate that sympathetic neurons in vivo alter their neurotransmitter phenotype in response to novel environmental signals and that sweat glands play a critical role in the cholinergic and peptidergic differentiation of the sympathetic neurons that innervate them. The sweat gland-derived cholinergic differentiation factor is distinct from leukemia inhibitory factor and ciliary neurotrophic factor, two well-characterized cytokines that alter the neurotransmitter properties of cultured sympathetic neurons in a similar fashion. Recent studies indicate that anterograde signalling is also important for the establishment of functional synapses in this system. We have found that the production of cholinergic differentiation activity by sweat glands requires sympathetic innervation, and the acquisition and maintenance of secretory competence by sweat glands depends upon functional cholinergic innervation.

Vanadium as a modulator of cellular regulatory cascades and oncogene expression

Vanadium, a trace metal in the environment and in biological systems, influences the behavior of enzymes, mimics and regulates growth factor activity, is a potential mutagenic and carcinogenic agent, and regulates gene expression. The diverse biological actions of vanadium result from its capacity to function as an oxyanion, oxycation, or prooxidant. Vanadium is found in water, rocks, and soils in low concentration and in relatively high concentrations in coal and oil deposits. Vanadium compounds at much higher concentrations than are typically ingested are being considered in the treatment of diabetes mellitus. The actions of insulin and vanadium on the insulin receptor are similar, but the mechanisms are not identical. Vanadium modulates growth-factor-mediated signal transduction pathways. Vanadium promotes cell transformation and diminishes cell adhesion. Consistent with its mitogenic action and its capacity to mimic mitogenic growth factors, vanadium stimulates expression of protooncogenes. In particular, oxygen-derived active species are involved in the expression of the jun protooncogene in the presence of vanadium. The unique cellular activity of vanadium makes it a tool of unparalleled potential for studying mechanisms of cell growth, differentiation, and metabolism.

Vanadate-induced gene expression in mouse C127 cells: roles of oxygen derived active species

An underinvestigated aspect of the mitogenic and cell regulatory actions of vanadium is the regulation of gene expression. Among the fifteen cellular genes studied in cultured mouse C127 cells, vanadium (as 10 microM sodium vanadate) increased levels of mRNA of the actin and c-Ha-ras to four times control values. These increases represented de novo synthesis of mRNA, since they were inhibited by actinomycin D. Vanadate did not increase mRNA corresponding to c-src, c-mos, c-myc, p53, HSP70, pODC or RB genes, and expression of c-erb A, c-erb B, c-sis and c-fes genes was undetectable whether vanadium was present or not. Expression of a third gene affected by vanadium, c-jun, was augmented by addition of a reductant or oxidant together with the vanadate. Addition of NADH (marginally effective on its own) or H2O2 (effective alone) dramatically enhanced the effect of vanadate on c-jun gene expression. Catalase inhibited the effect of NADH partly. The vanadate-stimulated expression of actin and c-Ha-ras mRNA were unaffected by oxidants, reductants, metal chelators, or anti-oxidant enzymes. Evidently vanadate acts by two separate mechanisms on these two categories of genes. The alternate hypothesis that the actions of vanadate on actin and c-Ha-ras were mediated by a protein kinase cascade was inconsistent with the following observations. Neither insulin nor epidermal growth factor increased mRNA levels of c-Ha-ras or actin gene. Neither genistein (a tyrosine kinase inhibitor) nor pretreatment with 12-O-tetradecanoylphorbol-13-acetate blocked the actions of vanadate on these genes. Clearly the biological actions of vanadium depend in part on altered expression of genes. Since two of the genes are proto-oncogenes, this mechanism is potentially relevant to the mitogenic responses of cells to vanadium.