Metallothionein in radiation exposure: its induction and protective role

Since its discovery about 40 years ago, there has been a wide interdisciplinary research interest in metallothionein (MT) on its physiological and toxicological aspects. Functionally, MT is involved not only in metal detoxification and homeostasis, but also in scavenging free radicals during oxidative damage. Among over 4500 publications which can be retrieved by Medline search, only about 50 reports have been published on the relationship of MT with ionizing and UV radiation. In this review, we have evaluated critically the published data on the induced synthesis of MT by radiation, and the potential functions of MT in radiation induced cell damage. MT mRNA expression or MT synthesis was found to be induced by exposure of cells in vitro or tissues in vivo to ionizing or UV radiation. In most of the studies in animals and tissue cultures, high doses of ionizing radiation were used to induce MT, and, therefore, it is difficult to extrapolate these results to low level of repeated exposures to radiation in humans. Induced synthesis of MT is considered as one of the mechanisms involved in the adaptive response to low dose radiation exposure. The presence of MT in normal cells may provide protective effects from radiation-induced genotoxicity and cytotoxicity. However, in tumor cells, the presence of MT can result in drug and radiation resistance as well. These effects are modulated by other cellular factors, besides MT, such as antioxidants, and by the cell cycle stages in cell proliferation and differentiation.

Method for edge detection based on phase jump in a differential interferometer

We describe a new method for edge detection that uses polarization mixing in a differential heterodyne interferometer. When one of the focused beams of the interferometer scans across an edge, a phase jump of 180 degrees takes place in the very small region of the edge if certain conditions are satisfied. We call this phenomenon phase jump. The conditions in which phase jump can occur are given. The theoretical analysis shows that the slope of a phase jump is infinite and is not affected by step height, the vibration of the sample, or the intensity variation of the light source. Therefore phase jump can be used as the precise index for edge detection. The experimental results show good agreement with the theoretical analysis.

On-axis beam extinction through diffraction design and analysis

To optimize the functions of the surface-relief diffractive optical elements for optical limiters and other applications, we present a systematic design and analysis with numerical illustrations of the transmission properties of different surface-relief phase gratings and Fabry-Perot elements. The spectral response and the tolerance of fabrication errors have been included. An analysis shows that the blazed grating and the echelon grating, a multilevel element as a substitute of the blazed grating, can make the on-axis transmittance very low (less than 1% with one grating) over the broad visible band with a large tolerance of fabrication errors. The results are highly significant for the design of optical-limiting devices.

Metallothionein and apoptosis in primary human hepatocellular carcinoma (HCC) from northern China

BACKGROUND

Metallothionein (MT), acting as an antioxidant and zinc binding protein, may play an important role in regulation of apoptosis. Its differential expression has been documented in various human tumours.

MATERIALS AND METHODS

MT expression by immunohistochemical staining with a polyclonal antibody and apoptotic cells (APC) by TUNEL technique were investigated in 20 cases of hepatocellular carcinoma (HCC) and 2 normal livers from Northern China. Adjacent normal liver was available from 9 of these cases and 6 had adjacent cirrhotic tissue. There was no difference for MT staining and incidence of APC between normal liver and adjacent normal liver, and thus both were used as control liver.

RESULTS

Control liver had consistent MT staining with very low incidence of APC. Adjacent cirrhotic liver showed the same intensity of MT staining, with a similar incidence of APC to control liver. Twelve of 20 HCC cases (60%) showed no MT staining, and the rest also showed a low grade of MT staining as compared with control or adjacent cirrhotic livers. The incidence of APC in HCC was markedly higher than that in control liver or adjacent cirrhotic liver. The negative correlation of numbers of APC with MT expression was statistically significant (p < 0.005). The high incidence of APC in liver with a low MT expression was confirmed in double staining for MT and APC.

CONCLUSIONS

The present investigation from Northern Chinese samples has shown that MT expression in HCC was different from that in other human tumours, such as breast carcinoma. This suggests a different pattern of expression of MT protein in these two kinds of cancer. This investigation is important in understanding the mechanisms of the drug resistance of tumour cells, and may help to design better treatment strategies.

Intercalated cytosine motif and novel adenine clusters in the crystal structure of the Tetrahymena telomere

The cytosine-rich strand of the Tetrahymena telomere consists of multiple repeats of sequence d(AACCCC). We have solved the crystal structure of the crystalline repeat sequence at 2.5 A resolution. The adenines form two different and previously unknown clusters (A clusters) in orthogonal directions with their counterparts from other strands, each containing a total of eight adenines. The clusters appear to be stable aggregates held together by base stacking and three different base-pairing modes. Two different types of cytosine tetraplexes are found in the crystal. Each four-stranded complex is composed of two intercalated parallel-stranded duplexes pointing in opposite directions, with hemiprotonated cytosine-cytosine (C.C+) base pairs. The outermost C.C+base pairs are from the 5'-end of each strand in one cytosine tetraplex and from the 3'-end of each strand in the other. The A clusters and the cytosine tetraplexes form two alternating stacking patterns, creating continuous base stacking in two perpendicular directions along the x - and z -axes. The adenine clusters could be organizational motifs for macromolecular RNA.

[Expression of human SRY gene and the DNA-binding property of its product]

OBJECTIVE

To investigate the role which human SRY gene plays in the regulation of the downstream gene.

METHODS

The fragment of SRY (sex determinating region on the Y chromosome) HMG domain was cloned into the expressing vector pET-15b. The hSRY gene recombinant plasmid-pETSY was transformed and expressed in E.coliBL21. The target protein was purified by pET His. Tag system. The DNA-binding retardation test and its competitive reaction were conducted between SRY protein and the fragment of Mullerian inhibiting substance (MIS) promoter.

RESULTS

The molecular weight of the expressed hSRY protein was shown to be approximately 21kD. The specific DNA binding property of SRY protein to the fragment of MIS was confirmed in the retardation test and its competitive reaction.

CONCLUSION

The results suggest that the product of SRY gene can bind the MIS promoter region and may initiate the transcription of MIS.

[Effect of Yangxue bushen tablet on ovarian function in animal model of Yang deficiency]

OBJECTIVE

To study the therapeutic mechanism of Yangxue Bushen tablet (tablet for nourishing blood and tonifying Kidney) on the Kidney deficiency type of functional amenorrhea and infrequent menstruation.

METHODS

Applied with orimeten, models of Yang deficiency in female rabbits were made, ikaclomine was taken as the control drug. Group I was the group of animal model of Yang deficiency; Group II was the ikaclomine treatment group; Group III was the high dosage treatment group; Group IV was the low dosage group; Group V normal rabbit treated with distilled water. The functional effect of gonadal axis was evaluated by the changes of the signs of animal histomorphology of ovary and uterus, and the level of beta-endorphin.

RESULTS

The animals of Yang deficiency in Group II, III and IV recovered as a whole, and the changes of different levels of folliculi, morphosis of endometria and deciduous vaginal epithelial cell in group II, III and IV were more obviously than those in group I and V (P < 0.05). The content of beta-endorphin in blood plasma in group I was 106.6 pg/ml, which was lower than those in the other groups (P < 0.05), and the contents of beta-endorphin in blood plasma, in group III, IV and II were similar to that in group V (P < 0.05).

CONCLUSION

Yangxue Bushen tablet has the effect on regulating menstruation by regulating the function of gonadal axis, regulating and promoting the ovarian function.

Protective role of zinc-metallothionein on DNA damage in vitro by ferric nitrilotriacetate (Fe-NTA) and ferric salts

Oxidative DNA damage can be caused by radicals generated by transitional metals like iron in Fenton reaction. Metallothionein (MT) may play an important role in preventing oxidative DNA damage. Therefore, after comparing the effects of ferric salts (Fe), and complexes of ferric salts with nitrilotriacetic acid (Fe-NTA) on DNA damage, the protective effects of zinc-MT (Zn-MT) on DNA damage of Fe salts or Fe-NTA were investigated in vitro. DNA damage was measured by loss of fluorescence of DNA binding to ethidium bromide, and also by increased DNA mobility in agarose gel electrophoresis. Both Fe salts and Fe-NTA could induce calf thymus DNA damage in presence of hydrogen peroxide and ascorbate. However, the degree of DNA damage was lower with Fe salts than that with Fe-NTA complex. Addition of 50 microM Zn-MT could only protect DNA from Fe-NTA, but not from Fe salt induced damage. The protective effect of MT was about five times better than that of glutathione (GSH). These results suggest a potential role for MT in protection from Fe-NTA-induced DNA damage.

Interferometer for small-angle measurement based on total internal reflection

We describe a new method for angle measurement based on the internal-reflection effect and heterodyne interferometry. A novel prism assembly is designed that can always parallel retroreflect the incoming light beams so the optical configuration is compact. As a differential common-path optical configuration is integrated into the design, the linearity of the method is greatly improved. Details of theoretical analysis of the method and experimental verification of the principle are presented. The resolution can be better than 0.3 arc sec. The experimental results and further improvements of the proposed method are also addressed.

Effects of gamma radiation on levels of brain metallothionein and lipid peroxidation in transgenic mice

The induction of metallothionein (MT) synthesis in the brain was investigated in MT-I isoform-overexpressing transgenic (MT-I*) and control mice after exposure to increasing doses of 2 to 20 Gy of whole-body gamma radiation. Although the MT-I isoform was the major isoform of MT in this transgenic mouse, the other isoforms, MT-II and MT-III, were also present in the brain. The total concentration of MT in the brain was measured by a cadmium-binding assay, while zinc and lipid peroxides were measured by atomic absorption spectrophotometry and by the thiobarbituric acid method, respectively. In MT-I* mice at 24 h after radiation exposure, the level of MT in the brain was increased from a basal level of 44.4 +/- 4.0 microg/g to a maximum level of 91.0 +/- 9.0 microg/g after 5 Gy and remained high after 10 and 20 Gy. In a time-course experiment with 5 Gy, the concentration of MT in the brain of MT-I* mice increased at 3 h and reached a maximum of 175.3 +/- 15.3 microg/g at 6 h. This high level of MT remained unchanged for 48 h after radiation exposure. Metallothionein was not induced markedly in the brains of control mice either at 24 h after exposure to 2-20 Gy gamma radiation or at different times after exposure to 5 Gy gamma radiation. In both strains of mice, the total concentration of zinc in the brain decreased with increasing radiation dose. No differences in lipid peroxide levels were seen in control mice exposed to 5 Gy at 6 and 12 h or after exposure to three other doses (2, 10 and 20 Gy) at 24 h. Slight increases (1.35 and 1.22, respectively) in lipid peroxide levels were observed in control mice at 24 and 48 h after exposure to 5 Gy. Lipid peroxide levels in the brain were not changed in irradiated MT-I* mice. The results show a marked increase in the levels of MT in the brain of transgenic mice after exposure to gamma radiation. The induced synthesis of MT may be only one of several mechanisms that prevent the induction of lipid peroxidation in the brain by gamma radiation.

[Prognosis of laryngeal carcinoma in youth]

The prognosis of 55 cases of laryngeal carcinoma in young people had been studied. The major factors mainly related to prognosis were smoking and misdiagnosis, while the tumour differentiation might be not so important. There was a high recurrence rate of 25.5% in the young patients and low 3- and 5-year survival rates of 47.4% and 34.5% respectively. The mortality of 1-year after surgery was 21.8%. The 3-and 5-year survival rates between total and partial laryngectomy made no difference. The survival rate of patients with positive node was lower. Early diagnosis is most important for young patients. Partial laryngectomy and neck dissection must be performed as far as possible.

[Interleukin-6 gene cloning, expression and purification]

OBJECTIVE

The main purpose of this paper is to study the batch production of recombinant human interleukin-6(rhIL-6).

METHODS

The cloned rhIL-6 gene is under the control of T7 promoter of pET30a vector and expressed in E. coli.

RESULTS

The ratio of expressed recombinant protein to total cell protein is more than 50%. The rhIL-6 molecular weight is 21,000, isoelectric point is 6.7. The purity of the rhIL-6 is more than 95%, and the activity of rhIL-6, determined by IL-6 dependent mice hybridoma cell line 7TD1 and MTT assay, is 0.35 ng/ml.

CONCLUSIONS

All results mentioned show that rhIL-6 meets the request of the middle scale production.

[The calculation of transitions 4s(2)4p-4s4p(2), 4s(2)4p-4s(2)5s, 4s(2)4p-4s(2)4d, 4s4p(2)-4p(3) and 4p(3)-4s(2)5s energy levels, wavelengths and oscillator strengthes in Ga-like ions from Z X-Rh XV]

In this paper, the 4s(2)4p, 4s(2)4d, 4s4p(2), 4p(3) and 4s(2)5s configuration's energy level structures, and configuration interactions in Ga-Like from Ga I-Xe XXIV ions are analysed in theory. The law of isoelectronic series is given. By using our fitted formula, the energies of Tc XIII ion 4s(2)4p, 4s4p(2) and 4s(2)5s configurations are predicted by interpolation, the energies of Tc IIIX-Rh XV ions 4p(3) and 4s(2)4d configurations are predicted by extrapolation. Wavelengths and oscillator strengthes (HXR theoretical calculation) of transitions 4s(2)4p-4s(2)4d, 4s(2)4p-4s4p(2), 4s(2)4p-4s(2)5s, 4p(3)-4s(2)5s and 4s(2)4p-4p(3) are given. The deviations of predictive energy levels from ob served values are less than 100cm(-1).

Autofocus laser rotary encoder

A laser incremental encoder with autofocus operation isproposed. In the encoder, an optical read head focuses three laserbeams upon a disk with a scaling grating. The scaling grating is areflection grating for which the height difference between adjacentpixels is one quarter of the wavelength of the laser. Each of thetwo laser beams is focused onto one of the two sections of thereflective grating, whereby the pitch of the grating can be detected byinterferometric reflection. The third beam acts to provideautofocus and is reflected from a smooth part between the two sectionsof the reflective grating. Therefore the encoder is less sensitiveto the gap between the optical read head and the scaling grating, andno precision adjustment is required. Also, the reading data arefree from the vibration and waviness of the grating surface. In theexperiments an encoder disk was fabricated from a wafer by lithographictechniques. The encoder with an 18-mm radius of the disk can reacha resolution of 2(16) = 65,536 pulses per revolution withoutelectronic interpolation.

Protective effects of extracted human-liver RNA, a known interferon inducer, against radiation-induced cytogenetic damage in male mice

Cells in vitro or in vivo pre-exposed to low-dose radiation (LDR) or low concentrations of chemical mutagens became more resistant to large-dose radiation-induced DNA or chromosome damage. This was known as radio-adaptive response, for which the exact mechanism was unclear. However, multiple cellular and molecular responses to LDR have been documented, for instance, the induction of some cytokines such as interferon (IFN). Administration of exogenous IFN to cultured cells or mice showed marked radio-protection. In the present study, we investigated the in vivo radio-protective effects of extracted human liver RNA (HL-RNA), a known IFN inducer, indirectly to determine the radio-protective action of endogenous IFN. First, mice were administered with 6.25 mg/kg HL-RNA at different times before exposure to radiation and the 24 h pretreatment offered the optimal protective action for HL-RNA on cytogenetic effects in bone marrow cells. When the mice were treated with different concentrations of HL-RNA for 24 h, a wide dose-range (25-100 mg/kg) of HL-RNA resulted in a marked protection from X-ray-induced chromosome aberrations in both bone marrow cells and germ cells. In subsequent experiments, a protective effect of pretreatment with 25 mg/kg HL-RNA for 24 h was also found for radiation-induced micronuclei in polychromatic erythrocytes (PCE), and inhibition of DNA repair ability (unscheduled DNA synthesis, UDS). These results demonstrated that HL-RNA, an IFN inducer, is able to offer significant cytogenetic protection from radiation, implying indirectly that the induction of IFN by LDR may also play a protective role as one of the mechanisms in the induction of the cytogenetic adaptive response.

Transforming growth factor-beta1 (TGF-beta1) in penile and prostate growth in the rat during sexual maturation

The goal of this study was to determine whether transforming growth factor-beta1 (TGF-beta1) may contribute to the arrest of penile growth and the down-regulation of androgen receptors (AR) that occur during sexual maturation in the rat penis. For this purpose, body, penis, and prostate weights were obtained from male rats of increasing ages, and penis and prostate TGF-beta1 concentrations were determined by a sandwich enzyme-linked immunosorbent assay. The cytosol fraction was obtained from the shafts and glandes of immature (19-day-old) and adult (90-day-old) rat penises, and ARs were measured by a western blot assay. The effect of exogenous TGF-beta1 on penile growth was examined in vivo in two groups of immature rats (21 and 27 days old) implanted with miniosmotic pumps delivering either human TGF-beta1 or vehicle only directly into the corpora cavernosa for 6 days. The penises, prostates, and testes were weighed, and the AR content was estimated by western blot. The growth rate of the penis declined after 8 weeks of age, whereas the ventral prostate growth rate increased until 14 weeks of age and then slowed down. The content of penile AR protein decreased seven-fold in the adult rats compared to the immature animals. Penile TGF-beta1 concentration increased nearly three-fold from the 19-day-old rats to a peak at 60 days of age and then decreased over the next 4 months to the initial levels. In contrast, TGF-beta1 concentration in the prostate was not significantly affected by age and remained below the lowest penile values in all age groups. Transforming growth factor-beta1 given locally to the penis reduced penile shaft weight by 38 and 22% in two groups of immature rats, while the weights of the penile glans, testis, and ventral prostate remained unaffected. Androgen receptor content was higher in the glans than in the shaft and was not changed by TGF-beta1 treatment. These results suggest that the increase of TGF-beta1 levels in the penis may reinforce growth arrest caused by the down-regulation of penile ARs, whereas the maintenance of a high content of ARs and a low TGF-beta1 concentration may allow prostate growth to continue.

Chemical oxidation and DNA damage catalysed by inorganic sunscreen ingredients

Titanium dioxide (TiO2) has been noted (US Federal Register, 43FR38206, 25 August 1978) to be a safe physical sunscreen because it reflects and scatters UVB and UVA in sunlight. However, TiO2 absorbs about 70% of incident UV, and in aqueous environments this leads to the generation of hydroxyl radicals which can initiate oxidations. Using chemical methods, we show that all sunscreen TiO2 samples tested catalyse the photo-oxidation of a representative organic substrate (phenol). We also show that sunlight-illuminated TiO2 catalyses DNA damage both in vitro and in human cells. These results may be relevant to the overall effects of sunscreens.

[Erythropoietin gene cloning and expression in S. cerevisiae]

Mature human erythropoietin gene was amplified from EPO cDNA by PCR methods. The PCR product was cloned into pUC18 plasmid at Sma I site, then precisely engineered into a intermidiate vector pSK43SB which were digested with Hind III, Mung bean nuclease, and Sal I. Then degest pSK43SB-EPO plasmid with EcoR I and Cla I, the EC fragment with an alpha-factor leading sequence, EPO gene and CYC1 terminater were produced. It was then cloned into a typical high efficiency episomal expression vector YEpHC8. Human EPO protein with highly mannose glycosylated was identified by Western blot methods in both secreted and in cells proteins. N-Glycosidase F digested secreted EPO can produce 20,000 EPO without N-glycosylation similar with that produced in cells.

[The cloning, expression, purification and bioactivity identification of recombinant IGF-I]

The fragment containing IGF-I cDNA and cyc1 terminator from PSK-IGF-I plasmid was cloned into PSK43 SB treated by Hind III, Klenow and Cla I, generating a recombinant PSB-IGF-I (DH), which have double Hind III sites. This plasmid was treated by Hind III and Klenow, ligated to give a recombinant plasmid PSB-IGF-I(NH), which has no Hind III site. After analysed by restriction endonucleases and sequencing, the fusion site was verified to be correct. This plasmid was excised and a BamH I-Cla I fragment containing yeast alpha-factor promotor, leader sequence, IGF-I cDNA and cycl terminator was cloned into yeast episomal plasmid vector YEpHC8, generating a recombinant plasmid YEpHC8-IGF-I. Transformed this plasmid into yeast competence cells BJ1990 by using LiAc method. The expressed products were secrected into the medium broth and having the correct molecular weight of 8,100 on SDS-PAGE. The products of IGF-I were raised by using high-cell-density fermentation of Saccharomyces cerevisiae. The cleared supernatant of yeast medium was applied to Bio-Rex 70 resin, eluted with 1 mol/L ammonium acetate, pH8.0. Main peak was pooled and applied to Bio-Gel P10 (200-400 mesh). The second peak was collected and get relatively pure IGF-I proteins. The biological activities of IGF I product was assayed in NIH3T3 cells by using MTT method. The results show that the expressed IGF-I can obviously stimulate NIH3T3 cells to proliferate at the concentration ranging from 10 ng/ml to 50 ng/ml, suggesting that the protein has its biological activities.

Tissue- and development-specific expression of multiple alternatively spliced transcripts of rat neuronal nitric oxide synthase

Nitric oxide (NO) functions as an intercellular messenger and mediates numerous biological functions. Among the three isoforms of NO synthase that produce NO, the ubiquitously expressed neuronal NO synthase (nNOS) is responsible for a large part of NO production, yet its regulation is poorly understood. Recent reports of two alternative spliceforms of nNOS in the mouse and in man have raised the possibility of spatial and temporal modulation of expression. This study demonstrates the existence of at least three transcripts of the rat nNOS gene designated nNOSa, nNOSb, and nNOSc, respectively, with distinct 5' untranslated first exons that arise from alternative splicing to a common second exon. Expression of the alternative transcripts occurs with a high degree of tissue and developmental specificity, as demonstrated by RNase protection assays on multiple tissues from both fetal and adult rats. Furthermore, terminal differentiation of rat pheochromocytoma-derived PC12 cells into neurons is associated with induction of nNOSa, suggesting, likewise, development- and tissue-specific transcriptional control of nNOS isoform expression. Physical mapping using a rat yeast artificial chromosome clone shows that the alternatively spliced first exons 1a, 1b, and 1c are separated by at least 15-60 kb from the downstream coding sequence, with exons 1b and 1c being positioned within 200 bp of each other. These findings provide evidence that the biological activity of nNOS is tightly and specifically regulated by a complex pattern of alternative splicing, indicating that the notion of constitutive expression of this isoform needs to be revised.

Antimicrobial compounds from Ceanothus americanus against oral pathogens

During the search for antimicrobial compounds from higher plant sources, a methanol extract of Ceanothus americanus demonstrated antimicrobial activity against selected oral pathogens. Through further bioassay-guided fractionation and purification, three triterpenes (ceanothic acid, 27-hydroxy ceanothic acid and ceanothetric acid) and two flavonoids (maesopsin and maesopsin-6-O-glucoside) were identified. Among these, ceanothetric acid and maesopsin-6-O-glucoside were new compounds. Ceanothic acid and ceanothetric acid demonstrated growth inhibitory effect against Streptococcus mutans, Actinomyces viscosus, Porphyromonas gingivalis, and Prevotella intermedia with MICs ranging from 42 to 625 micrograms ml-1. Maesopsin, its glucoside, and 27-hydroxy ceanothic acid, were inactive below the concentration of 500 micrograms ml-1.

Induction of apoptosis in the germ cells of adult male rats after exposure to cyclophosphamide

Treatment with cyclophosphamide, a commonly used anticancer drug, may result in oligozoospermia or azoospermia. The objective of this study was to determine whether exposure of male rats to cyclophosphamide induces apoptosis in male germ cells, and if so, when the peak of apoptosis occurs and at what specific stages of spermatogenesis. The presence of apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) detection in situ and by an increase in DNA fragmentation (DNA ladder). To determine the time course of drug-induced apoptosis, male Sprague-Dawley rats were treated with a single dose (70 mg/kg BW) of cyclophosphamide, and the testes were fixed 0, 4, 8, 12, 18, 24, and 48 h after treatment. To determine the dose response, rats were treated with doses of cyclophosphamide (0, 2, 7, 20, and 70 mg/kg), and the testes were fixed 12 h after treatment. A low spontaneous incidence of apoptosis was observed in controls, in particular in premeiotic germ cells of stages I-IV and XI-XIV of the seminiferous tubules. In cyclophosphamide-exposed rats, the incidence of apoptosis increased progressively at 4 h and 8 h, reached a peak at 12 h (about 3.5-fold above control), and then decreased rapidly to control levels by 48 h. A 70-mg/kg dose of cyclophosphamide induced a significant increase in apoptosis; lower doses did not. Although drug-induced apoptosis occurred in all stages of germ cells, it was most pronounced in spermatogonia and spermatocytes in stages I-IV and XI-XIV. Thus, apoptosis may be involved in the occurrence of oligozoospermia or azoospermia after cyclophosphamide treatment. Apoptosis of damaged premeiotic germ cells may serve a critical role in protecting subsequent generations from the diverse effects of toxicants.

[The simultaneous analysis of substance P, somatostatin, neurokinin and neurotensin by capillary zone electrophoresis]

Neuropeptides play an important part in several different areas of neurochemistry. Recently, capillary electrophoresis (CE) was developed for analysis of neuropeptides. This paper reports a capillary zone electrophoretic method for the simultaneous separation and quantitative determination of the substance P (SP), somatostatin (SS), neurokinin (NKA) and neurotensin (NT). The separation was performed on a 50microm x 60cm fused-silica capillary using 0.1mol/L at pH 2.7 phosphate as buffer. The eluted fractions were detected at 214nm.

Synchrony of clonal cell proliferation and contiguity of clonally related cells: production of mosaicism in the ventricular zone of developing mouse neocortex

We have analyzed clonal cell proliferation in the ventricular zone (VZ) of the early developing mouse neocortex with a replication-incompetent retrovirus encoding human placental alkaline phosphatase (AP). The retrovirus was injected into the lateral ventricles on embryonic day 11 (E11), i.e., at the onset of neuronogenesis. Three days postinjection, on E14, a total of 259 AP-labeled clones of various sizes were found in 7 fetal brains. There are approximately 7 cell cycles between E11 and E14 (), and there is a 1-2 cell cycle delay between retroviral injection and the production of a retrovirally labeled "founder" cell; thus, we estimate that the "age" of the clones was about 5-6 cell cycles. Almost one-half of the clones (48.3%) identified were pure proliferating clones containing cells only in the VZ. Another 18.5% contained both proliferating and postproliferative cells, and 33.2% contained only postproliferative cells. It was striking that over 90% of the clonally related proliferating cells occurred in clusters of two or more apparently contiguous cells, and about 73% of the proliferating cells occurred in clusters of three or more cells. Regardless of the number of cells in the clone, these clusters were tightly packed and confined to a single level of the VZ. This clustering of proliferating cells indicates that clonally related cells maintain neighbor-neighbor relationships as they undergo interkinetic nuclear migration and progress through several cell cycles, and, as a result, the ventricular zone is a mosaic of small clusters of clonally related and synchronously cycling cells. In addition, cells in the intermediate zone and the cortical plate were also frequently clustered, indicating that they became postproliferative at a similar time and that the output of the VZ is influenced by its mosaic structure.

Local homogeneity of cell cycle length in developing mouse cortex

We have measured the amount of variation in the length of the cell cycle for cells in the pseudostratified ventricular epithelium (PVE) of the developing cortex of mice on embryonic day 14. Our measurements were made in three cortical regions (i.e., the neocortex, archicortex, and periarchicortex) using three different methods: the cumulative labeling method (CLM), the percent labeled mitoses (PLM) method, and a comparison of the time needed for the PLM to ascend from 0 to 100% with the time needed for the PLM to descend from 100 to 0%. These 3 different techniques provide different perspectives on the cytokinetic parameters. Theoretically, CLM gives an estimate for a maximum value of the total length of the cell cycle (TC), whereas PLM gives an estimate of a minimum value of TC. The difference between these two estimates indicates that the range for TC is +/-1% of the mean TC for periarchicortex, +/-7% for neocortex, and +/-8% for archicortex. This was confirmed by a lengthening of the PLM descent time in comparison with its ascent time. The sharpness of the transitions and the flatness of the plateau of the PLM curves indicate that 99% of the proliferating cells are within this narrow estimated range for TC; hence, only approximately 1% deviate outside of a relatively restricted range from the average TC of the population. In the context of the possible existence within the cortical PVE of two populations with markedly dissimilar cell cycle kinetics from the mean, one such population must comprise approximately 99% of the total population, and the other, if it exists, is only approximately 1% of the total. This seems to be true for all three cortical regions. The narrow range of TC indicates a homogeneity in the cell cycle length for proliferating cells in three different cortical regions, despite the fact that progenitor cells of different lineages may be present. It further predicts the existence of almost synchronous interkinetic nuclear movements of the proliferating cells in the ventricular zone during early development of the cerebral cortex.

Construction and characterization of a 10-genome equivalent yeast artificial chromosome library for the laboratory rat, Rattus norvegicus

Increasing attention has been focused in recent years on the rat as a model organism for genetic studies, in particular for the investigation of complex traits, but progress has been limited by the lack of availability of large-insert genomic libraries. Here, we report the construction and characterization of an arrayed yeast artificial chromosome (YAC) library for the rat genome containing approximately 40,000 clones in the AB1380 host using the pCGS966 vector. An average size of 736 kb was estimated from 166 randomly chosen clones; thus the library provides 10-fold coverage of the genome, with a 99.99% probability of containing a unique sequence. Eight of 39 YACs analyzed by fluorescence in situ hybridization were found to be chimeric, indicating a proportion of about 20-30% of chimeric clones. The library was spotted on high-density filters to allow the identification of YAC clones by hybridization and was pooled using a 3-dimensional scheme for screening by PCR. Among 48 probes used to screen the library, an average of 9.3 positive clones were found, consistent with the calculated 10-fold genomic coverage of the library. This YAC library represents the first large-insert genomic library for the rat. It will be made available to the research community at large as an important new resource for complex genome analysis in this species.

Cancer chemopreventive activity of resveratrol, a natural product derived from grapes

Resveratrol, a phytoalexin found in grapes and other food products, was purified and shown to have cancer chemopreventive activity in assays representing three major stages of carcinogenesis. Resveratrol was found to act as an antioxidant and antimutagen and to induce phase II drug-metabolizing enzymes (anti-initiation activity); it mediated anti-inflammatory effects and inhibited cyclooxygenase and hydroperoxidase functions (antipromotion activity); and it induced human promyelocytic leukemia cell differentiation (antiprogression activity). In addition, it inhibited the development of preneoplastic lesions in carcinogen-treated mouse mammary glands in culture and inhibited tumorigenesis in a mouse skin cancer model. These data suggest that resveratrol, a common constituent of the human diet, merits investigation as a potential cancer chemopreventive agent in humans.

Bipolar esophageal electrocardiography by using standard limb leads

The ear-xiphisternum distance (EXD, the distance from the low edge of the ear to the xiphisternal basis in supine position) was used as a reference value for esophageal catheter insertion. ECGs recorded in the esophagus with bipolar electrocardiography using standard limb lead (ESLL) and conventional unipolar lead (ECUL) were compared. 112 patients with sinus rhythm and 76 patients during paroxysmal supraventricular tachycardia (PSVT) whose P-wave and QRS complex did not overlap were studied. The results suggested that in sinus rhythm the amplitude of the P-wave in ESLL was larger and the T-wave was smaller than in ECUL. During PSVT, the P-wave was much clear and higher in each lead of ESLL than that in ECUL. The ideal range of esophageal ECG recording was situated between the end of EXD and 6.5 cm proximal to it.

Comparative linkage mapping of human chromosome 13 and bovine chromosome 12

A comparative linkage map of human chromosome 13 and bovine chromosome 12 was constructed using eight polymorphic microsatellite markers associated with six specific genes. Linkage of these was also examined relative to five previously mapped anonymous microsatellite markers. Seven gene-linked markers were developed from bovine large-insert genomic clones containing one of five genes of interest (serotonin receptor subtype 2, fms-related tyrosine kinase, coagulation factor 10, retinoblastoma susceptibility gene, collagen type IV alpha 1), and one additional marker was developed from a microsatellite resident within an intron of the bovine dopachrome tautomerase gene. Four of these loci were previously assigned to bovine chromosome 12 by analysis of a somatic cell hybrid panel. This study provides linkage information for examining gene order in this conserved synteny group. The comparative linkage mapping results indicate that the q arm of human chromosome 13 is almost entirely conserved in bovine chromosome 12. One intrachromosomal rearrangement was detected in this linkage group relative to human, and this rearrangement was confirmed by fluorescence in situ hybridization results.

Compounds from Syzygium aromaticum possessing growth inhibitory activity against oral pathogens

A crude MeOH extract of Syzygium aromaticum (clove) exhibited preferential growth-inhibitory activity against Gram-negative anaerobic periodontal oral pathogens, including Porphyromonas gingivalis and Prevotella intermedia. By means of bioassay-directed chromatographic fractionation, eight active compounds were isolated from this extract and were identified as 5,7-dihydroxy-2-methylchromone 8-C-beta-D-glucopyranoside, biflorin, kaempferol, rhamnocitrin, myricetin, gallic acid, ellagic acid, and oleanolic acid, based on spectroscopic evidence. The antibacterial activity of these pure compounds was determined against Streptococcus mutans, Actinomyces viscosus, P. gingivalis, and P. intermedia. The flavones, kaempferol and myricetin, demonstrated potent growth-inhibitory activity against the periodontal pathogens P. gingivalis and P. intermedia.

Androgen and pituitary control of penile nitric oxide synthase and erectile function in the rat

Castration of adult male rats reduces by half the penile erectile response to electrical field stimulation (EFS) of the cavernosal nerve, and the activity of penile nitric oxide synthase (NOS). Both changes are prevented by androgen administration. We have now investigated whether other strategies of androgen ablation or competition may act as stronger inhibitors, and, if so, whether the stronger inhibition is due to the depletion of penile NOS content. Rats were castrated or left intact and were treated daily as follows: 1) intact, with the antiandrogen flutamide (25 mg/kg/day, i.p.); 2) castrated, with similar treatment; 3) castrated, with 17 beta-estradiol 3-benzoate (estradiol; via silastic tubing, s.c.). Additional groups of intact rats received injections of a GnRH antagonist (GnRHA, 1.25 mg/kg, s.c.), or were hypophysectomized and left untreated. Controls were untreated intact and castrated animals. After 7 days, rats were subjected to EFS, and the ratios between maximal intracavernosal pressure (MIP) and mean arterial pressure (MAP) were measured. Penile NOS activity and the contents of neuronal NOS (nNOS) and endothelial NOS (eNOS) were determined. Castration reduced the MIP:MAP ratio and penile NOS activity. Androgen receptor blockade with flutamide induced a similar response in intact rats. When flutamide treatment was combined with castration, the erectile response was nearly abolished, but NOS activity was not decreased below the values in castrated rats. Estradiol given to castrated rats and hypophysectomy or GnRHA treatment in intact rats diminished the erectile response below the level in castrated animals. In hypophysectomized rats, penile NOS activity fell below levels in castrated animals. contents of nNOS and eNOS were not significantly reduced by any treatment. These data suggest that penile erection in the rat is completely dependent on androgens, presumably because of their role in the maintenance of penile NOS activity and of other ancillary factors. However, only the complete blockade of residual androgen effects at the tissue level or a total androgen depletion can abolish the erectile response.

Adaptive response to ionizing radiation-induced chromosome aberrations in rabbit lymphocytes: effect of pre-exposure to zinc, and copper salts

Various stress conditions including exposure to low-dose radiation and low concentrations of chemical mutagens can induce an adaptive response to subsequent radiation-induced chromosome damage. In this study, the effect of pretreatment of rabbit lymphocytes with zinc or copper salts on radiation-induced chromosome damage was investigated. Pretreatment of rabbit peripheral lymphocytes with Zn (50 microM in vitro or 100 mumol/g body weight in vivo) resulted in resistance to gamma radiation (2.0 Gy)-induced chromosome aberrations such as dicentrics plus centric rings and cells with chromosome aberrations. On the other hand, pretreatment with Cu (50 microM in vitro) did not show any protective effect on radiation-induced chromosome damage in rabbit lymphocytes. However, the concentration of metallothionein increased in activated lymphocytes 24 h after in vitro pretreatment with both Zn and Cu. In addition, gamma-radiation-induced calf thymus DNA damage could be prevented directly by the addition of Zn-metallothionein in the cell-free system. These results suggest that the induction of zinc-metallothionein synthesis may act as one of the defensive mechanisms to the induction of cytogenetic adaptive response to ionizing radiation while copper-metallothionein did not show any radioprotective effect.

[A pathological survey of the therapeutic effect on experimental hypoxic-ischemic encephalopathy]

Rat models of the acute and recuperative phases of hypoxic ischemic encephalopathy (HIE) were established beginning by the 7th day after birth through ischemia and hypoxia. The prophylatic and therapeutic effects on experimental HIE were studied by the application of radix salviae miltiorrhizae, flunarizine and hyperbaric oxygen. Experimental data indicated that among these measures, radix salviae miltiorrhizae gave a better result and the pathological change in the prophylactic and therapeutic groups particularly the result of the latter one were light serious than those of the control group.

[A clinical-pathological study on hypoxic ischemic encephalopathy in 124 cases of perinates]

OBJECTIVE

To explore the morphological feature, its pathogenesis and clinical significance of hypoxic-ischemic encephalopathy (HIE) through pathological examinations.

METHODS

In addition to the routine pathologic examination, the brain tissues, including frontal lobus, temporal lobus, occipital lobus, hippocampus, capsula interna, cerebellum and medullary bulb, were sectioned and examined respectively.

RESULTS

(1) 93.5% of cases had a history of direct or indirect asphyxia. (2) The main pathological alterations were edema, congestion, hyaline thrombosis, haemorrhage, degeneration and necrosis of nerve cells. Softening, calcification, cavity formation and fibrosis were also seen in some cases.

CONCLUSIONS

The study suggested that congestion and edema of cerebral tissue were essential changes for the pathogenesis of HIE. Hemorrhage and necrosis were common pathological alterations. Fibrosis and cavitation were changes of convalescence. It is of primary importance to treat asphyxia during perinatal period for the prevention of HIE.

Reduction of penile nitric oxide synthase in diabetic BB/WORdp (type I) and BBZ/WORdp (type II) rats with erectile dysfunction

Erectile dysfunction occurs frequently in human diabetes, and it is sometimes associated with hypogonadism. These conditions also develop in a model of insulin-dependent (type I) diabetes, the BB/WORdp (diabetic prone) rat but have not yet been investigated in the model of insulin-resistant (type II) diabetes, the BBZ/WOR rat. It is also unknown whether diabetes-related impotence is due to reduced levels of the mediator of penile erection, nitric oxide, caused by a decrease of nitric oxide synthase (NOS) in the penis. To clarify these questions, groups (n = 5-6) of diabetic BB/WORdp (insulin-maintained) and BBZ/WOR rats were age-matched with diabetic-resistant BB/WORdr and non-diabetic BB/WORdp rats and submitted to determinations of serum glucose, testosterone, and penile reflexes (cups and flips). Erectile dysfunction was found in all of type I and in most of type II diabetic animals (glycemias of 25.0 and 31.1 mM), at the selected mean ages of 310 and 180 days old, respectively. This was evidenced by over 95% decreases of erectile reflexes in both types of diabetes and was accompanied by 75% reduction of serum testosterone. Soluble NOS activity was measured in penile tissue from the diabetic rats with impaired erectile reflexes and in the corresponding controls, by the (3H)-L-arginine/citrulline conversion assay. The neuronal NOS isoform (nNOS) content was determined by a semiquantitative western blot assay. Both types of diabetes showed a marked decrease of penile NOS activity (74 and 55%, respectively), and a lower reduction of penile nNOS content (47 and 33%, respectively). No endogenous NOS inhibitor was detected in the diabetic type I penile cytosol by cross-mixing NOS activity assays. Our data support a common etiology for erectile dysfunction present in rats with types I and II diabetes mellitus and suggest that the etiology is related to a decrease of penile NOS derived in part from serum androgen deficiency.

Restoration of normal adult penile erectile response in aged rats by long-term treatment with androgens

In order to determine whether the aging-related impairment of penile erection can be corrected by exogenous androgens, 20-mo-old ("old") rats received implants of Silastic tubing containing either testosterone (T) or dihydrotestosterone (DHT). Untreated aged-matched rats were used as reference controls, and values were compared with those obtained previously for 5-mo old ("adult") rats. After 45 days, groups of six rats were submitted to electrical field stimulation of the cavernosal nerve (EFS), and the intracavernosal pressure and mean arterial pressure (MAP) were recorded. Compared to the untreated old rats, the old animals receiving either T or DHT showed a similar and significant (p < 0.01) increase (56%) in the maximal intracavernosal pressure (MIP) to a level slightly above that of the untreated adult rats. The response was sensitive to the nitric oxide synthase (NOS) inhibitor Nw-nitro-L-arginine methyl ester (L-NAME). The MIP:MAP ratio in the treated animals was nearly double that found in the old untreated controls. Penile NOS activity was measured by the [3H]L-arginine-citrulline conversion, and neuronal NOS (nNOS) levels were estimated by a semiquantitative Western blot assay with antibodies against human nNOS. No significant variations were observed in either NOS levels or NOS activity between the treated and untreated old rats. These results suggest that aging-related erectile dysfunction in the intact rat may be responsive to androgen therapy and that this correction is not associated with an increase in the basal levels of penile NOS, in contrast to what occurs in castrated rats.

Construction and characterization of a bovine bacterial artificial chromosome library

A bacterial artificial chromosome (BAC) library has been constructed for use in bovine genome mapping using constructed for use in bovine genome mapping using the pBeloBAC11 vector. Currently, the library consists of 23,040 clones, which achieves a 70% probability (P=0.70) of the library containing a specific unique DNA sequence. Sixty thousand clones, or about three haploid bovine genomes, will be required to achieve a 95% probability (P=0.95) of containing a unique sequence. An average insert size of 146 kb was estimated from the analysis of 77 randomly selected BAC clones produced by one or two rounds of size selection. The bovine DNA inserts proved to be very stable for at least 100 cell generations. No chimeric clones were detected among 11 large, size-selected BAC clones using fluorescence in situ hybridization (FISH) on metaphase bovine chromosomes. Thirty-three of 46 (72%) sequences were present in the library in at least one copy, which is consistent with the estimated 70% probability of this library containing a unique DNA sequence. A BAC clone as sequence-tagged sites for genetic mapping. These markers cosegregated, and no recombinants were detected in 193 informative meioses. Plasmid end rescue and the inverse polymerase chain reaction methods were used to rescue both ends of this BAC clone, and chromosome walking was performed using PCR primers designed within the end region sequences. Based on our experimental results, the BAC system provides a very useful tool for complex genome analysis.

[Interleukin-2 gene cloning and expression in S. cerevisiae]

Mature human Interleukin-2 gene was amplified from IL-2 cDNA by PCR methods. The PCR product was cloned into pUC12 plasmid at Sma I site, then precisely engineered into an intermidiate vector pSK43SB which were digested with Hind III, mung bean nuclease, and Sal I. Added BamH I linker to Cla I site of pSK43SB-IL2 to produce one more BamH I site, then digested pSK43DB-IL2 with restriction enzyme BamH I, the BamH I fragment with an alpha-factor leading sequence, IL2 gene and cycl terminater were produced. It was then cloned into a typical high efficiency episomal expression vector YEpHc8. Human IL-2 protein was purified from supernatant secreted by yeast transformants of YEpHc8-IL2 leading by alpha-factor promoter with IL-2 right translational reading frame and accurate cleavage site. High level expression of IL-2 with highly activity has been purified. A sugar specific silver staining method and 3H sugar labelling experiment has shown the detection of carbohydrate component.

Mild hyperthermia can induce adaptation to cytogenetic damage caused by subsequent X irradiation

Many low-level environmental agents are able to induce an increased resistance to subsequent mutagenic effects induced by ionizing radiation. In this paper, an induced cytogenetic adaptation to radiation in human lymphocytes was studied with mild hyperthermia as the adaptive treatment and compared with that induced by low-dose radiation. We found that this adaptation could be induced not only in PHA-stimulated human lymphocytes (at 14, 38 and 42 h after addition of PHA), but also in unstimulated G0-phase cells (before addition of PHA) by mild hyperthermia (41 degrees C for 1 h) as well as 50 mGy X rays. When the two adaptive treatments were combined, no additive effects on the magnitude of the adaptation induced were observed, suggesting that low-dose radiation and hyperthermia may share one mechanism of induction of adaptation to cytogenetic damage. Some mechanisms which may be involved in the induction of adaptation to cytogenetic damage by low-dose radiation are discussed and compared with the effects of mild hyperthermia in inducing thermotolerance and radioresistance.

Mechanistic evaluation of new plant-derived compounds that inhibit HIV-1 reverse transcriptase

Swertifrancheside [1], a new flavonone-xanthone glucoside isolated from Swertia franchetiana, 1 beta-hydroxyaleuritolic acid 3-p-hydroxybenzoate [2], a triterpene isolated from the roots of Maprounea africana, and protolichesterinic acid [3], an aliphatic alpha-methylene-gamma-lactone isolated from the lichen Cetraria islandica, were found to be potent inhibitors of the DNA polymerase activity of human immunodeficiency virus-1 reverse transcriptase (HIV-1 RT), with 50% inhibitory doses (IC50 values) of 43, 3.7, and 24 microM, respectively. They were not cytotoxic with cultured mammalian cells. The kinetic mechanisms by which compounds 1-3 inhibited HIV-1 RT were studied as was their potential to inhibit other nucleic acid polymerases. Swertifrancheside [1] bound to DNA and was shown to be a competitive inhibitor with respect to template-primer, but a mixed-type competitive inhibitor with respect to TTP. On the other hand, 1 beta-hydroxyaleuritolic acid 3-p-hydroxybenzoate [2] and protolichesterinic acid [3] were mixed-type competitive inhibitors with respect to template-primer and noncompetitive inhibitors with respect to TTP. Therefore, the mechanism of action of 1 beta-hydroxyaleuritolic acid 3-p-hydroxybenzoate [2] and protolichesterinic acid [3] as HIV-1 RT inhibitors involves nonspecific binding to the enzyme at nonsubstrate binding sites, whereas swertifrancheside [1] inhibits enzyme activity by binding to the template-primer.

[Expression of desmoplakin II in tumors]

Desmoplakin II (DPII) is a new marker for identification of epithelium and epithelial tumors. Expression of DPII in 217 tumors cases was studied immunohistochemically by ABC method using an anti-DPII monoclonal antibody which reacts with tissue on formalin-fixed, paraffin-embedded sections. A monoclonal antibody against cytokeratin (CK) was employed to compare with the antibody. Immunohistochemical staining showed that 147 of the 163 epithelial tumors and bi-directional differentiation tumors expressed DPII (90.7%); 92 of the 163 tumors expressed CK (56.4%); 54 tumors lacking desmosome expressed neither DPII nor CK. All CK positive staining was located in cytoplasm while most DPII positive dotty staining was located at the cell-cell borders, some DPII staining was present in cytoplasm. These results demonstrate that the anti-DPII monoclonal antibody is a useful immunohistochemical probe for identification of desmosome-containing tumors. Antibodies against other epithelial markers such as keratin should be employed together with anti-DPII monoclonal antibody when differentiation is made between epithelial and non-epithelial tumors.

Metallothionein protects DNA from copper-induced but not iron-induced cleavage in vitro

Iron and copper ions mediate generation of reactive oxygen radicals from O2 and H2O2 by the Fenton reaction: these radicals are capable of damaging DNA. We studied (a) the ability of these metals to induce double-strand breaks in DNA in vitro in the presence of H2O2 and ascorbic acid as donors of reactive oxygen, and (b) the ability of the metal-binding protein metallothionein (MT) to protect DNA from damage. Strand cleavage was measured by loss of fluorescence after binding to ethidium bromide and by increased mobility of DNA in agarose. The results show that Cu(II), Fe(II) and Fe(III) all can induce damage to calf thymus DNA under our experimental conditions. Cu(II)-induced DNA damage was dose-dependent and the degree of damage was proportional to the concentration of H2O2. On the other hand, DNA fragmentation was significant only in the presence of high concentrations of Fe(II) or Fe(III). Addition of Zn-MT to the reaction mixture prior to addition of Cu(II) inhibited fragmentation of DNA in a dose-dependent manner but had little effect on iron induced damage. Other proteins (histone or albumin) were not effective in protecting DNA from Cu-induced damage, as compared to Zn-MT. The formation of Cu(I) from Cu(II) in the presence of hydrogen peroxide and ascorbate was also inhibited by addition of Zn-MT. Thus, MT may protect DNA from damage by free radicals by sequestering copper and preventing its participation in redox reactions.

A metal-dependent form of protein phosphatase 2A

Highly purified bovine heart protein phosphatase 2A catalytic subunit lost virtually all of its activity during storage at -70 degrees. When the enzyme was preincubated with Co2+, over 35% of the original activity was restored. Freshly prepared protein phosphatase 2A purified from bovine heart was stimulated at least 3 to 4-fold by pretreatment with Co2+ or Mn2+. Activation by Co2+ appeared to be irreversible whereas activation by Mn2+ was partially reversed after the cation was chelated with excess EDTA/EGTA. The sensitivity of Co2(+)-stimulated protein phosphatase 2A to okadaic acid or inhibitor-2 was similar to that of spontaneously active protein phosphatase 2A. The enzyme was converted to a latent form by treatment with phosphate or pyrophosphate. The latent form was completely reactivated by preincubation with Co2+. These results demonstrate that protein phosphatase 2A, like phosphatase 1, can exist in a metal ion-dependent form and may represent a new mechanism for the regulation of protein phosphatase 2A activity.

Induction of a cytogenetic adaptive response in germ cells of irradiated mice with very low-dose rate of chronic gamma-irradiation and its biological influence on radiation-induced DNA or chromosomal damage and cell killing in their male offspring

In earlier studies we have shown that either a single exposure or multiple exposures to a low dose of X-rays (0.05 Gy) induced a significant cytogenetic adaptive response in mouse germ cells. In this paper, a very low-dose rate (20 microGy/min) of chronic 60Co gamma-irradiation was used to pre-irradiate mice for 40 days. Then, another 40 days later, these mice were treated with a subsequent large dose of X-irradiation, followed 24 h later by cytogenetic analysis of their spermatocytes. Analysis for radiation-induced DNA and chromosomal damage was also carried out in splenocytes, bone marrow cells and spermatocytes of the offspring of mice adapted by the low-dose rate of chronic gamma-irradiation. Results demonstrated that (i) cumulative gamma-irradiation (1.10 Gy) at the dose rate 20 microGy/min induced a marked cytogenetic adaptive response in the mouse germ cells (stem spermatogonia); (ii) the sensitivity of offspring's bone marrow cells and spermatocytes to 1.5 Gy X-ray-induced chromosome aberrations was not influenced by the low-dose radiation delivered to paternal germ cells; (iii) either constitutive or post-irradiation DNA repair capacity (UV-induced unscheduled DNA synthesis, UDS) was not modified in the offspring's splenocytes; (iv) the sensitivity of the offspring's splenocytes to radiation-induced cell killing was also not altered. These results suggest that low-dose radiation delivered to the male parents with a significant induction of cytogenetic adaptive response in their germ cell does not likely cause any risk of damaging effects to the offspring of those irradiated male mice.

[Report of a case of glucagonoma misdiagnosed as "eczema" and "hepatic angioma" for three years and review of literature]

Glucagonoma is a rare pancreatic tumor, necrolytic migratory erythema is its distinctive feature and it is often associated with diabetes mellitus, weight loss, anemia, hypoaminoacidemia, glossitis and stomatitis. We reported a case of glucagonoma misdiagnosed as "eczema" and "benign hepatic anginoma" for 3 years. His blood glucagon level was 1,758 ng/L. The results of abdominal B-mode ultrasonography and CT scan were negative, but selected arteriogram showed a tumor mass between the pancreatic body and tail. Before operation, treatment with octreotide and supply of amino acids were given with improvement of the skin lesion. After resection of the tumor from pancreas, necrolytic migratory erythema disapeared, but his blood level of glucagon and amino acids did not improve. It is suggested that any diabetic patient with chronic skin damage should be checked for blood glucagon level. In suspected cases, selected arteriogram will be helpful for location of the tumor. Vigorous resection of the pancreatic tumor should be done as soon as possible, even though there is already metastases.

Pre-exposure of mice to low dose or low dose rate ionizing radiation reduces chromosome aberrations induced by subsequent exposure to high dose of radiation or mitomycin C

The phenomenon of cytogenetic adaptive and cross-adaptive response induced by low dose irradiation and chemical mutagen in mice is described. We found, firstly, that adaptation can be induced by acute low dose X-irradiation (0-100 mGy). Secondly, a cross-adaptation can occur between X-irradiation and mitomycin C (MMC). And finally, mice pre-exposed to chronic low dose rate 60Co-Gamma irradiation (0-226.0 mGy/day) are less susceptible to chromosome aberration induced by subsequent acute higher X-irradiation. Therefore, our data suggest that radioadaptive response depends on dose, dose rate and time interval. Possible mechanisms are also discussed.

Isolation and structural elucidation of pentacyclic triterpenoids from Maprounea africana

Pentacyclic triterpenoids based on the taraxer-14-ene skeleton with a C-28 attached carboxylic acid group have been isolated from the roots of Maprounea africana. These compounds were identified as 1 beta,2 alpha-dihydroxyaleuritolic acid 2,3-bis-p-hydroxybenzoate [1], 2 alpha-hydroxyaleuritolic acid 3-p-hydroxybenzoate [2], 2 alpha-hydroxyaleuritolic acid 2,3-bis-p-hydroxybenzoate [4], aleuritolic acid 3-p-hydroxybenzoate [5], aleuritolic acid [6], and aleuritolic acid 3-acetate [7]. Compounds 1 and 2 are new triterpene esters. Compound 3 was previously reported as 7 beta-hydroxymaprounic acid 3-p-hydroxybenzoate [13]. However, based on detailed nmr studies, its structure has been revised.

Crystal structure of a four-stranded intercalated DNA: d(C4)

The crystal structure of d(C4) solved at 2.3-A resolution reveals a four-stranded molecule composed of two interdigitated or intercalated duplexes. The duplexes are held together by hemiprotonated cytosine-cytosine base pairs and are parallel stranded, but the two duplexes point in opposite directions. The molecule has a slow right-handed twist of 12.4 degrees between covalently linked cytosine base pairs, and the base stacking distance is 3.1 A. This is in general agreement with the NMR studies. A biological role for DNA in this conformation is suggested.