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.

Intercellular space is affected by the polysialic acid content of NCAM

We have previously proposed that polysialic acid (PSA), which is attached to NCAM on the cell surface, can serve to regulate a variety of cell-cell interactions. The present study provides evidence that hydrated PSA influences a sufficiently large volume at the cell surface to exert broad steric effects, and that the removal of PSA in fact causes a detectable change in intercellular space. Using F11 neuron/neuroblastoma hybrid cells as a model system, the measured density and size of PSA suggests that a substantial fraction of the space between two apposed cell surface membranes could be sterically influenced by the presence of PSA. Specific enzymatic removal of PSA, which is similar in magnitude to changes that occur in many tissues during normal development, caused about a 25% decrease in the distance between two apposed cells. By contrast, removal of both heparan sulfate and chondroitin sulfate from the cells had no effect on this parameter. It is proposed that such changes in membrane-membrane distance could serve to alter selectively the efficiency of encounter between complementary receptors on apposing cells, and explain at least in part the broad biological influences of PSA.

Differential determination of chromium(VI) and total chromium in natural waters using flow injection on-line separation and preconcentration electrothermal atomic absorption spectrometry

A rapid, sensitive and selective method for the differential determination of CrIII and CrVI in natural waters is described. Chromium(vi) can be determined directly by flow injection on-line sorbent extraction preconcentration coupled with electrothermal atomic absorption spectrometry using sodium diethyldithiocarbamate as the complexing agent and C18 bonded silica reversed-phase sorbent as the column material. Total Cr can be determined after oxidation of CrIII to CrVI by potassium peroxydisulfate. Chromium(III) can be calculated by difference. The optimum conditions for sorbent extraction of CrVI and oxidation of CrIII to CrVI are evaluated. A 12-fold enhancement in sensitivity compared with direct introduction of 40 microliters samples was achieved after preconcentration for 60 s, giving detection limits of 16 ng l-1 for CrVI and 18 ng l-1 for total Cr (based on 3 sigma). Results obtained for sea-water and river water reference materials were all within the certified range for total Cr with a precision of better than 10% relative standard deviation in the range 100-200 ng l-1. The selectivity of the determination of CrVI was evaluated by analysing spiked reference materials in the presence of CrIII, resulting in quantitative recovery of CrVI.

[Quality of tuberous root of Liriope spicata (Thunb.) Lour. var. prolifera Y.T.Ma and Ophiopogon japonicus (L.F.) Ker-Gawl.--comparison of immune function]

This paper deals with comparative study on the immune function of the tuberous root of Liriope spicata var. prolifera and Ophiopogon japonicus. The results showed that the aqueous extract of both species mentioned above could increase obviously the spleen weight (immunity organ) of mice, enhance the clearance rate of iv charcoal particles in mice and antagonize remarkably the leukopenia caused by cyclophosphamide.

Microcapsules through polymer complexation. II. By complex coacervation of polymers containing a low charge density

Relationships between ionizable group content, structure and molecular weight, solubility and solution behaviour, and the efficacy of ionic complex formation through complex coacervation, have been established for a range of sparingly soluble synthetic weak polyelectrolyte polymers with low charge content, based on hydroxyalkyl methacrylates. Selected polymers containing methacrylic acid (acidic) and dimethylaminoethyl methacrylate (basic) functionality show promise as capsule-forming pairs for the entrapment of mammalian cells. The solubility of basic polymers and their ability to form microcapsules with structural integrity is enhanced through quaternization of the N-methyl functionality to the quaternary ammonium group. The survival of guinea-pig erythrocytes encapsulated for 4 d in this promising system was shown by the Drabkin's test to be about 41% of the control sample.

[Antimutagenicity screening of water extracts from 102 kinds of Chinese medicinal herbs]

Our observation shows that out of 102 kinds of Chinese medicinal herbs tested, 17 have remarkable antimutagenic effect on the mutation induced by aflatoxin B1, in Ames test. Among the 17 herbs Glycyrrhiza uralensis, Bupleurm chinense, Portulaca grandiflora and Cnidium monnieri have been found in other tests to be effective against mutagenesis induced by cyclophosphamide in mice.