The comet assay in clinical practice

The comet assay is a single-cell gel electrophoresis technique that measures DNA damage in individual cells. Since radiation produces 3-4 times more DNA damage in well-oxygenated cells compared with hypoxic cells, this assay can quantify the fraction of radiation-resistant hypoxic cells found in many solid tumours. This paper summarizes our results with 73 accessible metastatic tumours irradiated with palliative intent. Hypoxic fractions ranged from 0.0 to 0.67 with a mean of 0.15; 62% of these advanced tumours showed a hypoxic fraction > 0.05. Comparisons between two sequential aspirates in 33 tumours gave a slope of 0.92 (r2 = 0.88), suggesting that a single aspirate is generally representative of the tumour. A limitation, however, is that the hypoxic fraction could not be measured in clinical samples given a conventional dose of 2 Gy.

Crystal structure of an inhibitor complex of the 3C proteinase from hepatitis A virus (HAV) and implications for the polyprotein processing in HAV

The proteolytic processing of the viral polyprotein is an essential step during the life cycle of hepatitis A virus (HAV), as it is in all positive-sense, single-stranded RNA viruses of animals. In HAV the 3C proteinase is the only proteolytic activity involved in the polyprotein processing. The specific recognition of the cleavage sites by the 3C proteinase depends on the amino acid sequence of the cleavage site. The structure of the complex of the HAV 3C proteinase and a dipeptide inhibitor has been determined by X-ray crystallography. The double-mutant of HAV 3C (C24S, F82A) was inhibited with the specific inhibitor iodoacetyl-valyl-phenylalanyl-amide. The resulting complex had an acetyl-Val-Phe-amide group covalently attached to the S(gamma) atom of the nucleophilic Cys 172 of the enzyme. Crystals of the complex of HAV 3C (C24S, F82A) acetyl-Val-Phe-amide were found to be monoclinic, space group P2(1), having 4 molecules in the asymmetric unit and diffracting to 1.9-A resolution. The final refined structure consists of 4 molecules of HAV 3C (C24S,F82A) acetyl-Val-Phe-amide, 1 molecule of DMSO, 1 molecule of glycerol, and 514 water molecules. There are considerable conformational differences among the four molecules in the asymmetric unit. The final R-factor is 20.4% for all observed reflections between 15.0- and 1.9-A resolution and the corresponding R(free) is 29.8%. The dipeptide inhibitor is bound to the S(1)(') and S(2)(') specificity subsites of the proteinase. The crystal structure reveals that the HAV 3C proteinase possesses a well-defined S(2)(') specificity pocket and suggests that the P(2)(') residue could be an important determinant for the selection of the primary cleavage site during the polyprotein processing in HAV.

Line Broadening and the Temperature Exponent of the Fundamental Band in CO-N(2) Mixtures

We have measured the width, Gamma, of many P and R lines of the fundamental vibration-rotation band of CO perturbed by N(2) at 348 K and pressures of about 50 kPa. We have also extended the measurements made earlier at room temperature. The broadening coefficients, gamma = Gamma/pressure, were obtained with an accuracy of 0.3% by fitting with a Lorentzian, a Voigt, and an empirical lineshape model that blends together a hard-collision model and a speed-dependent Lorentzian profile. In all cases the results are represented by an empirical exponential power law polynomial in the line number, m. Combining the data at the two temperatures yields the exponent n in the scaling law gamma(T(1))/gamma(T(2)) = (T(1)/T(2))(-n), as a function of line number. The broadening coefficients and the variation of the temperature exponent line number are compared with theory. In addition, the line-mixing parameters are also reported at 348 and 301 K. Copyright 1999 Academic Press.

[A study on the T-cell subsets and glucocorticoid receptor in children with anaphylactoid purpura]

To study the changes of T-cell subsets and glucocorticoid receptor (GCR) in children with anaphylactoid purpura. T-cell subsets and GCR were measured respectively by cytotoxicity assay and GCR radioligand-binding assay in peripheral blood lymphocytes from 35 children with anaphylactoid purpura and 35 normal children. The result showed that the average percentages of CD3+, CD4+ cell subtypes and the CD4+/CD3+ ratio were 46.03% +/- 9.40%, 31.06% +/- 6.80% and 1.23 +/- 0.33 respectively, and the GCR numbered 3060 +/- 2153 binding sites per cell in the study group, on the other hand, the average percentages of CD3+, CD4+ cell subtypes and the CD4+/CD3+ ratio were 53.11% +/- 5.40%, 35.01% +/- 4.41% and 1.52 +/- 0.26 respectively, and the GCR numbered 5210 +/- 1639 binding sites per cell in the control group. These indicate that and that patients with anaphylactoid purpura may have abnormal immunomodulations and decreased GCR numbers per cell, which may have effects on the immune dysfunctions in the pathogenesis of anaphylactoid purpura.

Case study of the effects of atmospheric aerosols and regional haze on agriculture: an opportunity to enhance crop yields in China through emission controls?

The effect of atmospheric aerosols and regional haze from air pollution on the yields of rice and winter wheat grown in China is assessed. The assessment is based on estimates of aerosol optical depths over China, the effect of these optical depths on the solar irradiance reaching the earth's surface, and the response of rice and winter wheat grown in Nanjing to the change in solar irradiance. Two sets of aerosol optical depths are presented: one based on a coupled, regional climate/air quality model simulation and the other inferred from solar radiation measurements made over a 12-year period at meteorological stations in China. The model-estimated optical depths are significantly smaller than those derived from observations, perhaps because of errors in one or both sets of optical depths or because the data from the meteorological stations has been affected by local pollution. Radiative transfer calculations using the smaller, model-estimated aerosol optical depths indicate that the so-called "direct effect" of regional haze results in an approximately 5-30% reduction in the solar irradiance reaching some of China's most productive agricultural regions. Crop-response model simulations suggest an approximately 1:1 relationship between a percentage increase (decrease) in total surface solar irradiance and a percentage increase (decrease) in the yields of rice and wheat. Collectively, these calculations suggest that regional haze in China is currently depressing optimal yields of approximately 70% of the crops grown in China by at least 5-30%. Reducing the severity of regional haze in China through air pollution control could potentially result in a significant increase in crop yields and help the nation meet its growing food demands in the coming decades.

Evolutionary pattern of influenza B viruses based on the HA and NS genes during 1940 to 1999: origin of the NS genes after 1997

Phylogenetic analysis was carried out for genes encoding hemagglutinin (HA) (24 new and 25 previously reported sequences) and nonstructural proteins (NS) (22 new and 14 previously reported sequences) of influenza B virus isolates obtained from 1940 to 1999. Two antigenically and genetically distinct HA lineages are presently known to exist. Divergence into these two lineages was estimated to have occurred around 1969. Phylogenetic analysis of NS genes revealed that their phylogenetic relationships were not linked to the two HA lineages but suggested that reassortment of viral genes between the viruses of two HA lineages had occurred. In addition two distinct NS lineages which were not linked to the two HA lineages were observed. Viruses isolated after 1997 formed their own lineage in combination with B/Houston/84 while other virus isolates obtained from 1973 to 1995 comprised the other NS lineage.

Pig xenogeneic antigen modification with green coffee bean alpha-galactosidase

Green coffee bean alpha-galactosidase can cleave the terminal alpha-galactose (alphaGal) on oligosaccharides that form the major antigen on pig endothelial cells recognized by primate-specific antibodies. Studies have been made of the conditions under which it is functional (e.g. temperature, pH) and of its biochemical and immunologic effects. Pig-to-rhesus monkey vein transplants were studied to identify the efficiency of the enzyme in delaying hyperacute rejection. When a graft became occluded, biopsies were taken for light microscopy (hematoxylin and eosin), scanning electron microscopy (SEM) and immunostaining with Griffonia simplicifolia IB4 lectin (GSIB4), and for IgM, IgG and C3. alpha-Galactosidase was stable for 72-96 h and was effective at 4 degrees C and pH 6.9 (conditions of human liver graft storage), although better function was obtained at 20 degrees C and pH 6.5. Using the porcine PK15 cell assay, the cytotoxicity of human serum was reduced after treatment of the pig cells with the enzyme. In vitro studies demonstrated that porcine veins treated with alpha-galactosidase lost endothelial expression of the Gal epitope within 30 min. SEM, however, demonstrated endothelial damage beginning within 2 h, probably caused by the alpha-galactosidase, as no damage was found in phosphate-buffered saline-treated veins, where the Gal epitope was preserved for >3 h. No change was found in either group on light microscopy. In vivo studies demonstrated that patency of the alpha-galactosidase-treated veins (mean 2.5 h) was longer than that of untreated veins (0.23 h) (P < 0.01). Biopsies showed no GSIB4 lectin staining for alpha-Gal epitopes and much less IgM and C3 deposition in the treated group. Light microscopy and SEM demonstrated more severe endothelial damage, hemorrhage, and fibrin formation in the untreated group. Galactosidase is effective in removing the terminal alphaGal and delays the onset of hyperacute rejection of pig veins transplanted into monkeys. However, its effect is temporary and, on its own, its use is unlikely to prolong survival of pig organs transplanted into primates sufficiently to be of clinical value.

An analysis of the role of neuraminidase in the receptor-binding activity of influenza B virus: the inhibitory effect of Zanamivir on haemadsorption

We analysed the role of neuraminidase (NA) on haemadsorption by the haemagglutinin (HA) protein of influenza B virus. The influenza B virus mutant ts-7 has a temperature-sensitive mutation in the NA protein. At high temperature, cells infected with this virus did not exhibit haemadsorption activity, but the addition of bacterial neuraminidase (bNA) restored haemadsorption activity. COS cells transfected with HA cDNAs of B/Kanagawa/73 or B/Lee/40 virus showed no evidence of haemadsorption. However, with the addition of bNA or co- transfection with NA cDNA of the B/Lee/40 virus, haemadsorption was observed. Experiments with point-mutated HA cDNAs of B/Lee/40 virus showed that two N-acetyl glycosylation sites at amino acid residues 160 and 217 were responsible for the inability of the HA protein to adsorb to erythrocytes. These results indicated that haemadsorption by the HA protein of influenza B virus required the involvement of NA. Because the NA inhibitor Zanamivir was reported not to penetrate cells, we investigated the action of this inhibitor and found that Zanamivir inhibited haemadsorption on MDCK cells infected with B/Kanagawa/73 or B/Lee/40 virus. After removing Zanamivir by washing, the addition of bNA restored the haemadsorption activity on the infected cells. Scanning electron microscopy indicated that at 0.4 microM Zanamivir, HA protein did not adsorb to erythrocytes but retained the ability to aggregate virions. However, at 4 microM Zanamivir, distinct virion formation could not be observed.

Involvement of peripheral NMDA and non-NMDA receptors in development of persistent firing of spinal wide-dynamic-range neurons induced by subcutaneous bee venom injection in the cat

To study the roles of peripheral excitatory amino acids receptor subtypes N-methyl-D-aspartate (NMDA) and non-NMDA receptors in persistent nociception, extracellular single unit recording technique was used to assess the effects of a single dose NMDA and non-NMDA receptor antagonists, AP(5) (5-aminophosphonovaleric acid) and CNQX (6-cyano-7-nitroquinoxaline-2,3-dione) or DNQX (6,7-dinitroquinoxaline-2,3-dione), on s.c. bee venom-induced increase in firing of wide-dynamic-range (WDR) neurons in the spinal dorsal horn of the urethane-chloralose anesthetized cats. Subcutaneous bee venom injection into the cutaneous receptive field resulted in a single phase of increased firing of WDR neurons over the background activity for more than 1 h. Local pre-administration of AP(5) (200 microg/100 microl) or CNQX (8.3 microg/100 microl) into the bee venom injection site produced 94% (1.01+/-0.96 spikes/s, n=5) or 76% (2.97+/-0.58 spikes/s, n=4) suppression of the increased neuronal firing when compared with local saline (16.32+/-4.55 spikes/s, n=10) or dimethyl sulfoxide (DMSO) (12.37+/-6.36 spikes/s, n=4) pre-treated group, respectively. Local post-administration of the same dose of AP(5) produced a similar result to the pre-treatment group with a 67% inhibition of the mean firing rate, however, the same treatment with CNQX and even a higher dose of DNQX (100 microg/100 microl) did not produce any inhibition of the neuronal firing induced by s.c. bee venom injection (DNQX vs. DMSO: 23.91+/-0. 25 vs. 22.14+/-0.04 spikes/s, P=0.0298, n=5). In the control experiments, local pre-administration of the same dose of AP(5) or CNQX into a region on the contralateral hindpaw symmetrical to the bee venom injection site produced no significant influence on the increased firing of the WDR neurons [contralateral AP(5) vs. saline: 14.17+/-6.27 spikes/s (n=5) vs. 16.32+/-4.55 spikes/s (n=10), P0.05; contralateral CNQX vs. DMSO: 12.85+/-6.38 spikes/s (n=4) vs. 12. 37+/-6.36 spikes/s (n=4), P0.05], implicating that the suppressive action of local AP(5) or CNQX was not the result of systemic effects. The present results suggest that activation of the peripheral NMDA receptors is involved in both induction and maintenance, while activation of non-NMDA receptors is only involved in induction, but not in the maintenance of persistent firing of the dorsal horn WDR neurons induced by s.c. bee venom injection.

Primary hyperalgesia to mechanical and heat stimuli following subcutaneous bee venom injection into the plantar surface of hindpaw in the conscious rat: a comparative study with the formalin test

To elucidate the underlying mechanisms of pathological pain, it is important and necessary to develop an animal model characterized by both spontaneous tonic pain and hyperalgesia with a prolonged duration post-tissue injury. In this report, we investigated whether the two animal models of spontaneous tonic pain (the formalin test and the bee venom test) could develop a hyperalgesia to mechanical and thermal stimuli in the injured area following subcutaneous (s.c. ) administration of the two chemical agents into the plantar surface of one hindpaw in the conscious rats. It was found that the persistent nociceptive response (flinching and lifting/licking the injected hindpaw) was monophasic and lasted for 1-2 h followed by a 72-96 h period of reduction in mechanical threshold and heat latency of withdrawal reflex in the bee venom injection area; however, in contrast, the spontaneous pain-related response was biphasic followed by a permanent hypoalgesia or analgesia in the formalin injection area although the duration and response intensity of spontaneous pain was comparable with those following bee venom treatment. Subcutaneous. bee venom injection also produced a distinct reduction of heat latency on the contralateral hindpaw, while s.c. formalin did not. On the other hand, s.c. bee venom injection produced a striking edema and redness of the plantar surface for nearly the same period as the development of hyperalgesia, while the edema and redness could not be obviously observed after the formalin treatment. In the control study, repetitive suprathreshold mechanical or heat stimuli applied to the plantar surface with or without saline treatment did not significantly influence the mechanical threshold or heat latency, suggesting that the phenomena of mechanical and heat hyperalgesia were not the effects of vehicle treatment or those of the stimulus modalities themselves. Taken together, our present results showed that in contrast to s.c. formalin injection, subcutaneous. bee venom injection produced little tissue damage but a striking inflammation accompanied by a prolonged spontaneous pain and a pronounced primary hyperalgesia to mechanical and heat stimuli in the treated hindpaw and a heat, but not mechanical, hyperalgesia in the contralateral hindpaw, implicating that bee venom model may have more advantages over the formalin test and probably other chemoirritants to study the neural mechanisms underlying pathological pain and, especially, the relationship between spontaneous pain and development of hyperalgesia.

Phosphoryl oxime inhibition of acetylcholinesterase during oxime reactivation is prevented by edrophonium

Reactivation of organophosphate (OP)-inhibited acetylcholinesterase (AChE) is a key objective in the treatment of OP poisoning. This study with native, wild-type, and mutant recombinant DNA-expressed AChEs, each inhibited by representative OP compounds, establishes a relationship between edrophonium acceleration of oxime-induced reactivation of OP-AChE conjugates and phosphoryl oxime inhibition of the reactivated enzyme that occurs during reactivation by pyridinium oximes LüH6 and TMB4. No such recurring inhibition could be observed with HI-6 as the reactivator due to the extreme lability of the phosphoryl oximes formed by this oxime. Phosphoryl oximes formed during reactivation of the ethoxy methylphosphonyl-AChE conjugate by LüH6 and TMB4 were isolated for the first time and their structures confirmed by (31)P NMR. However, phosphoryl oximes formed during the reactivation of the diethylphosphoryl-AChE conjugate were not sufficiently stable to be detected by (31)P NMR. The purified ethoxy methylphosphonyl oximes formed during the reactivation of ethoxy methylphosphonyl-AChE conjugate with LüH6 and TMB4 are 10- to 22-fold more potent than MEPQ as inhibitors of AChE and stable for several hours at pH 7.2 in HEPES buffer. Reactivation of both ethoxy methylphosphonyl- and diethylphosphoryl-AChE by these two oximes was accelerated in the presence of rabbit serum paraoxonase, suggesting that organophosphorus hydrolase can hydrolyze phosphoryl oxime formed during the reactivation. Our results emphasize that certain oximes, such as LüH6 and TMB4, if used in the treatment of OP pesticide poisoning may cause prolonged inhibition of AChE due to formation of phosphoryl oximes.

[Experimental research on in vivo gene-therapy of retinoblastoma]

OBJECTIVE

To investigate the expression condition of exogenous Rb gene in nude mouse vitreous transplanted retinoblastoma(RB) and its influence on the growth of the RB tumor in vivo.

METHODS

Establishing the model of RB transplantation in nude mouse vitreous, followed by constructing the retrovirus vector of Rb gene and transfecting it into the model by using liposome. The expression condition of Rb gene was analyzed by immunohistochemistry and flow cytometry. The growth condition of the RB transplantation tumor was examined ophthalmologically and pathologically.

RESULTS

The exogenous Rb gene expressed in the RB transplantation tumor for at least 7 days and partially suppressed the growth of the RB tumor. The level of suppression was related with the amount of the Rb protein expressed and the time to transfect the Rb gene after the RB transplantation tumor was established.

CONCLUSION

The exogenous Rb gene can express in the RB transplantation tumor and can partially suppress the growth of the RB tumor in vivo.

Lineshifts in the Fundamental Band of CO: Confirmation of Experimental Results for N(2) and Comparison with Theory

We have used a three-channel version of a tunable difference frequency laser spectrometer to measure the collisionally induced lineshifts at room temperature for 26 lines of the fundamental band of CO perturbed by nitrogen. Each lineshift was obtained directly by comparing the line center positions of two simultaneous recordings, one for a pressure-shifted line, and the other for the same line in pure CO line at very low pressure. The experimental results are found to be in complete agreement with earlier measurements and confirm that shifts as small as 3 MHz may be measured in such a system. Our results are compared with theoretical calculations. The part of the shifting coefficient antisymmetric with respect to a change in sign of the line number m, is in disagreement with the calculations. Copyright 1999 Academic Press.

[The spectral study of the surface modified medical rubber]

In this article ,the drug-resistance of two kinds of medical rubber whose surfaces have been modified were investigated by ATR-FTIR and XPS. The experimental results show that the compositions of the two samples'surface and body are different. The surface is fluorinated rubber although the body is butyl rubber. The ratio of fluorine to carbon atom in sample Ii -1 is higher than that in sample I -1. The principal join between F and C is the form--CF2--in sample II -1,but in sample I -1 it is the form--CF2-- and--CHF--. The change for F/C of the different depth in sample II- 1 was relatively less than that in sample I -1 when they were etched by argon ion bundle in the same conditions.

[Chemotherapeutic failure in micrometastasis in peripheral blood of patients with colorectal carcinomas]

OBJECTIVE

To study chemotherapeutic failure in the micrometastasis in peripheral blood of patients with colorectal carcinomas and its clinical significance.

METHODS

We investigated the changes of micrometastasis in peripheral blood of patients with colorectal carcinomas before and after chemotherapy.

RESULTS

The positive rate of CK2O mRNA in peripheral blood was 58.3%. Five more positive cases were detected 3 days after operation than before operation. After early short-term chemotherapy following operation, 22 cases turned to be negative. The maintaince of micrometastasis in peripheral blood after chemotherapy was significantly related to bcl-2 expression and p53 mutation in cancer tissues.

CONCLUSIONS

The early short-term chemotherapy after operation plays a role in controlling the micrometastasis of colorectal carcinoma. The study of chemotherapeutic effect on micrometastasis in peripheral blood and its relation with the related genes may contribute to the selection of drugs and plans of adjuvant treatment.

[Clinical and experimental study of jianruling in treating hyperplasia of mammary gland]

OBJECTIVE

To observe the therapeutic effect of Jianruling (JRL) on hyperplasia of mammary gland (HMG) and to explore its mechanism in regulating sex hormones.

METHODS

Clinical changes of HMG were observed and serum sex hormones measured before and after JRL treatment. In experimental study, the effect of JRL was estimated by using electron microscope, pathologic and radioimmunoassay.

RESULTS

JRL could not only cure HMG, but also regulate the sex hormone secretion both in HMG patients and in rats. Clinical study showed that the clinical cure rate was 72.5%, and the total effective rate was 90.8%, it demonstrated a significant difference in comparing with the control group, P < 0.01. The estradiol and prolactin levels of patients lowered significantly after JRL treatment, P < 0.05, while progestogen and testosterone increased significantly, P < 0.05, but no significantly change of follicle-stimulating hormone and luteinizing hormone was found. JRL showed marked effect in treating and preventing experimental HMG in rats, it could modulate the secretive function of sex hormone, and improve the construction of mammary gland.

CONCLUSION

JRL has significant effect in treating HMG, it can adjust the endogenous sex hormone level, delay the development of chronic cystic hyperplasia of mammary gland.

Role of edrophonium in prevention of the re-inhibition of acetylcholinesterase by phosphorylated oxime

We examined the role of edrophonium in the acceleration phenomenon using mouse wild-type and mutant D74N AChE inhibited with 7-(O,O-diethyl-phosphinyloxy)-1-methylquinolinium methylsulfate (DEPQ). With DEPQ-inhibited wild-type mouse acetylcholinesterase (AChE), the reactivation kinetic profile demonstrated one-phase exponential association only when 2-[hydroxyimino methyl]-1-methylpyridinium chloride (2-PAM) and 1-(2-hydroxy-iminomethyl-1-pyridinium)-1-(4-carboxy-aminopyridi nium)-dimethyl ether hydrochloride (HI-6) were used as reactivators. When 1,1[oxybis-methylene)bis[4-(hydroxyimino)methyl] pyridinium dichloride (LüH6) and 1,1-trimethylene bis(4-hydroxyimino methyl) pyridinium dichloride (TMB4) were used, the reactivation kinetic profile was biphasic in nature. Edrophonium had no effect on reactivation by 2-PAM and HI-6, but significantly accelerated LüH6- and TMB4-induced reactivation of DEPQ-inhibited wild-type mouse AChE. Comparison of the initial and overall reactivation rate constants with five oximes indicated that acceleration by edrophonium may be due to the prevention of re-inhibition of the reactivated enzyme by the phosphorylated oxime (POX) produced during the reactivation. With LüH6 and TMB4, about 2.5-fold increase in the reactivation rate constants was observed in the presence of edrophonium, but little or no effect was observed with the other three oximes. The initial reactivation rate constants were 5.4- and 4.2-fold of the overall rate constants with LüH6 and TMB4 as reactivators respectively, however, very little change was found between the initial and overall rate constants with the other three oximes. In experiments with D74N AChE, for which the inhibition potency of charged organophosphate (OP) was two to three orders less than wild-type enzyme, edrophonium had no effect on the reactivation by LüH6 and TMB4 and the time courses of reactivation were monophasic. The data from mutant enzyme substantiate the involvement of edrophonium in protecting POX re-inhibition of reactivated enzyme formed during the reactivation of OP-inhibited AChE.

Molecular cloning and spatial expression of an ApL1 cDNA for the large subunit of ADP-glucose pyrophosphorylase from Arabidopsis thaliana

A cDNA, ApL1a, corresponding to a homologue of the large subunit of ADP-glucose pyrophosphorylase (AGPase), has been isolated/characterised by screening a cDNA library prepared from leaves of Arabidopsis thaliana, followed by rapid amplification of cDNA 3'-ends (3'-RACE). Within the 1685 nucleotide-long sequence (excluding polyA tail), an open reading frame encodes a protein of 522 amino acids (aa), with a calculated molecular weight of 57.7 kDa. The derived aa sequence does not contain any discernible transit peptide cleavage site motif, similarly to two other recently sequenced full-length Arabidopsis homologues for AGPase, and shows ca. 58-78% identity to homologous proteins from other plants/tissues. The corresponding gene was found to be expressed in all tissues examined (rosette and stem leaves, stems, flowers and fruits). The ubiquitous expression of the gene is consistent with its critical role in starch synthesis in Arabidopsis.

Comparison between the comet assay and the oxygen microelectrode for measurement of tumor hypoxia

BACKGROUND AND PURPOSE

Hypoxic cells are present in some solid tumours and are known to limit radiocurability. To compare two measures of tumour hypoxia, 25 patients with locally advanced disease and accessible tumours or metastatic nodes were examined using an oxygen microelectrode and the alkaline comet assay.

MEASUREMENTS AND METHODS

For the comet assay, fine needle aspirate biopsies were taken immediately following a dose of 5-10 Gy. Single cells were examined for radiation-induced DNA strand breaks, and the percentage of radio-resistant hypoxic cells within the population was calculated from DNA damage histograms. For oxygen tension (pO2) measurements, multiple tracks were made using an Eppendorf oxygen microelectrode. The possibility that application of the first method might influence hypoxic fraction measurement by the second method was examined in a more controlled system by creating four tracks in murine SCC-VII tumours using an oxygen electrode, and measuring hypoxic fraction at subsequent times.

RESULTS

For 28 tumours from 25 patients, hypoxic fraction measured by comet assay correlated with the percentage of PO2 values < 5 mmHg (r2 = 0.46, P < 0.001). The mean comet hypoxic fraction was 0.36 for five tumours with a median PO2 < 10 mmHg. For the remaining 23 tumours with a median PO2 > 10 mmHg, the mean hypoxic fraction was 0.09. Advancement of an oxygen electrode through SCCVII tumours had no significant effect on hypoxic fraction measured 5 min to 24 h later using the alkaline comet assay.

CONCLUSIONS

Tumours defined as hypoxic based on a median pO2 < 10 mmHg appear to contain more than 20% radio-biologically hypoxic cells as estimated by the comet assay. In an animal tumour model, puncture of the tumour with an oxygen electrode did not influence hypoxic fraction measured using the comet assay, in agreement with the clinical data that the order in which the two methods were performed was not important.

[The detection and its clinical significance of cancer cells in portal vein blood of patients with colorectal carcinoma]

OBJECTIVE

To study the relation between cancer cells in portal vein blood and liver metastasis of colorectal carcinoma.

METHODS

The presence of CK20 mRNA was investigated by non-isotope RT-PCR in 54 cases.

RESULTS

The positive rate of CK2O mRNA in portal vein blood was 75.9%. The positive cases were significantly correlated with Dukes stage and live metastasis. There was a higher probability of liver metastasis in positive cases after operation.

CONCLUSIONS

The detection of CK20 in portal vein blood may improve the accuracy of clinical staging and diagnose liver micrometastasis of colorectal carcinoma.

[The relationship between the expression of transferrin receptors (TfR) on leukemia cells and the cell proliferation and iron metabolism status in childhood acute leukemias]

OBJECTIVE

To explore the relationship between transferrin receptor (TfR) expression and cell proliferation capacity and iron metabolism status.

METHODS

The binding site numbers and dissociation constant (Kd) of TfR of leukemic cells were assayed by radio-ligand binding assay.

RESULTS AND CONCLUSION

The binding site numbers of TfR were (7.826 +/- 6.054) x 10(4) sites/cell in ALL group and (20.406 +/- 17.876) x 10(4) sites/cell in AML group, and the Kds of TfR were (6.468 +/- 4.777) nmol/L and (8.683 +/- 4.890) nmol/L, respectively. The binding sites of TfR were significantly less in complete remission group than in relapsed or dead groups. There was a positive relationship between the TfR binding sites and the 3H-TdR incorporation in the leukemic cells (AML and ALL) and in the phytohemagglutinin stimulated peripheral mononuclear cells. In both ALL and AML group, the SF, CF were higher and Tf, TIBC were lower than those in control group. TfR binding sites were positively correlated with SF and CF, and negatively with Tf.

[Tissue reaction and degradation of super-high molecular weight poly D, L-lactic acid mini-plates and screws: an animal experiment]

OBJECTIVE

To investigate the tissue reaction and degradation processes of the super-high molecular weight(Mv = 6.0 x 10(5) kD) poly D, L-lactic acid(PDLLA) mini-plates and screws through the internal fixation for zygomatic arch fracture.

METHODS

It was carried out by the self-contrast study method and comparing with the titanium mini-plates and screws.

RESULTS

There was no side-effects on bone healing. The reaction of soft and hard tissues to PDLLA mini-plates and screws was similar to that of the titanium mini-plates and screws. No complication had been seen with the use of PDLLA mini-plates and screws, including infection, foreign body reaction and underlying osteolysis. The PDLLA devices had no changes in shape after 3 months, and then became the grains in different sizes after 6 months, and were completely resorbed within 12 months in vivo.

CONCLUSION

The super-high molecular weight PDLLA mini-plates and screws has good biocompatibility and proper degradation time. It is safe and effective to use the mini-plates and screws made of the super-high molecular weight PDLLA for internal fixation of bone.

[Internal fixation for zygomatic arch fracture with super-high molecular weight poly D, L-lactic acid mini-plates and screws: a study in dogs]

OBJECTIVE

To investigate the internal fixation effects of super high molecular weight (Mv = 6.0 x 10(5) kD) poly D, L-lactic acid(PDLLA) mini-plates and screws.

METHODS

10 dogs were utilized in this experiment with the self-contrast study method, comparing with the titanium mini-plates and screws.

RESULTS

The mechanical properties of the PDLLA mini-plates and screws appeared to be sufficient to enable undisturbed healing of depressed zygomatic arch fracture.

CONCLUSION

The good fixation effect of PDLLA mini-plates and screws was as same as that of the titanium mini-plates and screws without the need of secondary operation.

Expression of barley ADP-glucose pyrophosphorylase in Escherichia coli: processing and regulatory considerations

Full length cDNAs for barley ADP-glucose pyrophosphorylase (AGPase) coding for the large subunits of the endosperm and leaf homologues of the enzyme (AGPase-S1 and -S2, respectively) and for the small subunit protein from endosperm (AGPase-B1), have been expressed in Escherichia coli. The cDNAs for AGPase-S1 and -S2 required different induction conditions for their maximal expression and they encoded immunologically distinct proteins. The AGPase-S1 that was produced by E. coli had the same M(r) (58 kDa) as the corresponding protein in barley crude endosperm extracts, whereas the bacteria-produced AGPase-S2 (55 kDa) was larger than its counterpart from barley leaf preparations (53 kDa). An enzymatically active AGPase expressed in E. coli from a double construct containing cDNAs for AGPase-S1 and -B1 subunits was insensitive to the activation by 3-phosphoglycerate and to inhibition by inorganic phosphate, similarly to the enzyme in barley endosperm. Neither AGPase-S1 nor -B1 were active when expressed alone in the bacteria. The data are discussed with respect to possible mechanisms of intracellular targeting of immature AGPase-S proteins in barley tissues and regarding previous data on effector regulation of the barley enzyme.

Pericardial devascularization combined with Latarjet's innervation in the treatment of patients with portal hypertension

OBJECTIVE

To study the effect of pericardial devascularization combined with Latarjet's innervation on portal hypertension.

METHODS

Forty-eight patients undergoing pericardial devascularization combined with Latarjet's innervation were compared with 57 patients with devascularization. Clinical results were evaluated by postoperative portal vein pressure, postoperative rebleeding, operative mortality, abdominal distension, sudden diarrhea, and gastric retention.

RESULTS

The incidence of rebleeding, mortality, abdominal distension, sudden diarrhea, and gastric retention was 2%, 6.3%, 6.3%, 4.2% and 0% respectively in pericardial devascularization combined with Latarjet's innervation, and 12.5%, 12.3%, 24.6%, 15.6% and 14% respectively in devascularization.

CONCLUSIONS

Pericardial devascularization combined with Latarjet's innervation preserves the normal function of gastric emptying. This method plays an important role in maintaining nutritional supply and digestive function.

Spatial and temporal expression of c-Fos protein in the spinal cord of anesthetized rat induced by subcutaneous bee venom injection

In order to study central neuronal components involved in subcutaneous (s.c.) bee venom-induced persistent pain (a new tonic pain model), we use Fos immunostaining technique to study the spatial and temporal patterns of neuronal activity in the spinal cord of anesthetized rats. Following intraplantar bee venom injection, Fos-like immunoreactive (ir) neurons were only seen from L1 to S3 rostrocaudally with distinct distribution at L4-5 segments. At segments of L1-2 and S1-3, Fos-ir labelings were diffusely and symmetrically distributed on both sides of the gray matter; however, at L4-5 segments, Fos-ir neurons were densely localized in medial portion of laminae I-II, less densely in laminae V-VI and a few in laminae VII and X ipsilateral to the injection side. No Fos labeling was seen in ventral horn of the spinal cord at L4-5 segments. Fos protein began to express only within lamina I at 0.5 h, but increased over the whole dorsal horn at 1 h and reached peak labeling at 2 h after bee venom. Expression of c-Fos in laminae I-II decreased at 4 h, and completely disappeared at 24 h, however, labeling in laminae V-VI disappeared much slowly and existed even at 96 h after bee venom. Within laminae III-IV, Fos-ir neurons could not be seen at 0.5 h, but began to be seen at 1 h and appeared to exist even at 24 h after bee venom. Systemic morphine suppressed c-Fos expression dose-dependently in both superficial and deep layers of dorsal horn and the latter region was much more sensitive to morphine than the former one. The present results demonstrated that prolonged neuronal activities in superficial and deep layers of dorsal horn were essential to mediation of bee venom induced tonic pain and may have different roles in generation and/or modulation of spontaneous pain and hyperalgesia and allodynia.

Cell fusion studies to examine the mechanism for etoposide resistance in Chinese hamster V79 spheroids

When exposed to etoposide, the outer cells from Chinese hamster V79 spheroids are about 10 times more resistant to DNA strand breaks and cell killing than V79 cells grown as monolayers. Previous results have shown that the outer cells of both spheroids and monolayers grow at the same rate and contain the same amount and activity of the target enzyme, topoisomerase II. In order to examine possible mechanisms for this resistance, cell fusion studies were conducted with fluorescent dye-tagged monolayer and spheroid cells. Fused cells were exposed for 30 min to 1.2 microg/ml etoposide and then separated using fluorescence-activated cell sorting into binucleate cells consisting of two monolayer cells, two spheroid cells, or a mixed doublet consisting of one cell of each type. Individual sorted cell doublets were examined for the presence of etoposide-induced DNA strand breaks using the alkaline comet assay. As expected, doublets of monolayer cells were sensitive to etoposide and doublets of spheroid cells were resistant. However, mixed doublets were as resistant to DNA damage by etoposide as spheroid doublets. In comparison, when etoposide- or adriamycin-resistant V79 monolayer cells were fused to the parent monolayer cells, the expected intermediate sensitivity to etoposide was observed for the mixed doublets. We conclude that etoposide resistance associated with the outer cells of spheroids can be "transferred" to produce resistance in monolayer cells. Rapid changes in phosphorylation that can affect topoisomerase II activity or localization, or that can alter chromatin structure, are suggested as possible mechanisms of resistance. In support of this hypothesis, topo IIalpha phosphorylation was at least 10 times greater in monolayers than in the outer cell layer of spheroids.

Anti-BSA antibodies do not cross-react with the 69-kDa islet cell autoantigen ICA69

In contrast to several previously published reports, we demonstrate by a variety of antibody assays that bovine serum albumin (BSA) is not antigenically cross-reactive with the 69-kDa islet cell autoantigen (ICA69). Fast protein liquid chromatography purified BSA and highly purified recombinant human ICA69 were used to establish sensitive Western blot and ELISA assays in order to detect antibodies against these two proteins. The assays excluded BSA or powdered milk as blocking agents, since these would interfere with antibody binding. A panel of sera from diabetic individuals, first degree relatives, and normal controls showed that the majority (approximately 70%) of individuals from each group had antibodies against ICA69 as assayed by Western blots, whereas considerably fewer (approximately 13%) had anti-BSA antibodies on Western blots, and individuals with antibodies to both proteins occurred only rarely (2-3%). To explore this issue further we immunized a total of 16 individual rats, representing four different strains (bio-breeding diabetes resistant and diabetes prone, Wistar-Furth, and Sprague-Dawley), with either BSA (n = 2 of each strain) or with recombinant ICA69 (n = 2 of each strain), and for each animal pre- and postimmune antibody titres against BSA and against ICA69 were assayed separately by enzyme-linked immunoabsorbent assay. In rats immunized with BSA, anti-BSA titres increased about 100,000-fold over preimmune levels, whereas anti-ICA69 reactive antibodies were unchanged over preimmune levels. Similarly, in rats immunized with ICA69, anti-ICA69 titres rose about 100,000-fold over preimmune levels, whereas anti-BSA antibodies were unchanged over preimmune levels. Thus we find no evidence for the existence of antibody cross-reactivity between ICA69 and BSA, either in humans or in immunized rats. When our rat anti-BSA antisera were used to probe Western blots made from rat islets isolated in the strict absence of fetal calf serum, we were unable to detect a 69-kDa band, even when the islets were preincubated with gamma-interferon, a treatment which has been reported to induce the BSA cross-reactive islet antigen. We conclude that BSA is not antigenically cross-reactive with ICA69 at the antibody level, and it is highly unlikely that BSA is antigenically cross-reactive with some other 69 kD islet cell antigen.

Acceleration of oxime-induced reactivation of organophosphate-inhibited fetal bovine serum acetylcholinesterase by monoquaternary and bisquaternary ligands

Reactivation of organophosphate (OP)-inhibited acetylcholinesterase (AChE) by oximes is the primary reason for their effectiveness in the treatment of OP poisoning. Reactivation is reported to accelerate by quaternary ligands such as decamethonium, which is devoid of nucleophilicity. The mechanism of this enhancement is not known. To better understand the acceleration phenomenon, we examined ligand modulations of oxime-induced reactivation of methylphosphonylated AChE using 7-(methylethoxyphosphinyloxy)-1-methylquinolinium iodide and fetal bovine serum AChE. Edrophonium, decamethonium, and propidium, three quaternary AChE ligands of different types, were tested as potential accelerators. Experiments were carried out with both soluble enzyme preparation and AChE conjugated to polyurethane. Kinetic measurements with oximes 2-[hydroxyiminomethyl]-1-methylpyridinium chloride, 1,1'-trimethylene bis-(4-hydroxyimino methyl)-pyridinium dibromide, and 1, 1'-[oxybis-methylene)bis[4-(hydroxyimino)methyl]pyridiniu um dichloride showed that in the presence of 50 microM edrophonium, the reactivation rate constants increased 3.3-12.0-fold; 200 microM decamethonium produced a 1.6-3.0-fold enhancement of reactivation rate constants by the same oximes. Reactivation of the inhibited enzyme by 1-(2-hydroxyiminomethyl-1-pyridinium)-1-(4-carboxy-aminopyridinium )-d imethyl ether hydrochloride, 1-(2-hydroxyiminomethyl-1-pyridinium)-1-(3-carboxy-aminopyridinium )-d imethyl ether hydrochloride, and 1-[[[4-(aminocarbonyl)pyridino]methoxy]methyl]-2, 4, -bis(hydroxyimino)methyl pyridinium dichloride was not affected by either ligand. Propidium slowed the reactivation of 7-(methylethoxyphosphinyloxy)-1- methylquinolinium iodide-inhibited AChE by all oximes. Results suggest that the accelerator site may reside inside the catalytic gorge rather than at its entrance and acceleration may be due to the prevention of reinhibition of the regenerated enzyme by the putative product, the phosphonylated oxime. In addition to the nucleophilic property of the oximate anion, some of the reactivators may carry an accelerating determinant, as characterized with respect to edrophonium and decamethonium. Results offer possible explanations for the superiority of 1-(2-hydroxyiminomethyl-1-pyridinium)-1-(4-carboxy-aminopyridinium )-d imethyl ether hydrochloride over other oximes in the reactivation of specific AChE-OP conjugates.

[The study and application of software (LLLZ) connecting the data processing programme with PW1404 X-ray fluorescence spectrometry (II)]

The software LLLZ was applied to the analysis of geological powder sample. The original data could be used directly and quickly, and the analytical method could be chosen fast with this software, which was easily developed and used.

Nuclear localization is required for function of the essential clock protein FRQ

The frequency (frq) gene in Neurospora encodes central components of a circadian oscillator, a negative feedback loop involving frq mRNA and two forms of FRQ protein. Here we report that FRQ is a nuclear protein and nuclear localization is essential for its function. Deletion of the nuclear localization signal (NLS) renders FRQ unable to enter into the nucleus and abolishes overt circadian rhythmicity, while reinsertion of the NLS at a novel site near the N-terminus of FRQ restores its function. Each form of FRQ enters the nucleus soon after its synthesis in the early subjective day; there is no evidence for regulated sequestration in the cytoplasm prior to nuclear entry. The kinetics of the nuclear entry are consistent with previous data showing rapid depression of frq transcript levels following the synthesis of FRQ, and suggest that early in each circadian cycle, when FRQ is synthesized, it enters the nucleus and depresses the level of its own transcript.

[Expression of CD44 molecule and its significance in uveal and conjunctival melanomas]

The aim of this study was to evaluate the role of over expression of CD44 molecule in the development and progression of uveal and conjunctival melanomas. Flow cytometry (FCM) and immunofluorescence methods were used for detecting the CD44V expression in uveal malignant melanomas (UMM), conjunctival nevi (CN) and conjunctival malignant melanomas(CMM). The expression content of CD44 in 7 cases of CMM was significantly higher than that in 5 cases of CN (P < 0.05); the CD44V positive expression percentages in 7 cases of CMM and 40 cases of UMM were 71.43% and 62.50% respectively; the expression content of CD44V in UMM was related to scleral invasion (P = 0.0105); there was a negative correlation between the expression content of CD44V and proliferative index (PI), S-phase fraction (SPF) (P < 0.01; P < 0.05). The results suggested that the over expression of CD44V might be involved in the development of CMM and UMM and related to local infiltration ability of UMM and that the CD44V expression content detected by FCM might be helpful in discriminating CN From CMM, but this waited for further research confirmation.

Bilateral testicular tumors in an infant

A 7-month-old infant showed bilateral enlarged, nontender scrotal masses. The level of alpha-fetoprotein was greater than 10,000 ng/ml preoperatively; a high left inguinal orchiectomy was performed for a suspected yolk-sac tumor. The right testis was diagnosed as a mature teratoma because it was not possible to establish a line of cleavage between the tumor and the normal tissue, and a high right inguinal orchiectomy was performed. Only one case of bilateral testicular teratomas has been reported in the literature to date. We report a rare second case of bilateral testicular tumors, one a yolk-sac tumor and the other a teratoma.

Blockade of T-cell activation by dithiocarbamates involves novel mechanisms of inhibition of nuclear factor of activated T cells

Dithiocarbamates (DTCs) have recently been reported as powerful inhibitors of NF-kappaB activation in a number of cell types. Given the role of this transcription factor in the regulation of gene expression in the inflammatory response, NF-kappaB inhibitors have been suggested as potential therapeutic drugs for inflammatory diseases. We show here that DTCs inhibited both interleukin 2 (IL-2) synthesis and membrane expression of antigens which are induced during T-cell activation. This inhibition, which occurred with a parallel activation of c-Jun transactivating functions and expression, was reflected by transfection experiments at the IL-2 promoter level, and involved not only the inhibition of NF-kappaB-driven reporter activation but also that of nuclear factor of activated T cells (NFAT). Accordingly, electrophoretic mobility shift assays (EMSAs) indicated that pyrrolidine DTC (PDTC) prevented NF-kappaB, and NFAT DNA-binding activity in T cells stimulated with either phorbol myristate acetate plus ionophore or antibodies against the CD3-T-cell receptor complex and simultaneously activated the binding of AP-1. Furthermore, PDTC differentially targeted both NFATp and NFATc family members, inhibiting the transactivation functions of NFATp and mRNA induction of NFATc. Strikingly, Western blotting and immunocytochemical experiments indicated that PDTC promoted a transient and rapid shuttling of NFATp and NFATc, leading to their accelerated export from the nucleus of activated T cells. We propose that the activation of an NFAT kinase by PDTC could be responsible for the rapid shuttling of the NFAT, therefore transiently converting the sustained transactivation of this transcription factor that occurs during lymphocyte activation, and show that c-Jun NH2-terminal kinase (JNK) can act by directly phosphorylating NFATp. In addition, the combined inhibitory effects on NFAT and NF-KB support a potential use of DTCs as immunosuppressants.

Cross-clade human immunodeficiency virus (HIV)-specific cytotoxic T-lymphocyte responses in HIV-infected Zambians

We have examined cross-clade HIV-specific cytotoxic T-lymphocyte (CTL) activity in peripheral blood of eight Zambian individuals infected with non-B-clade human immunodeficiency virus type 1 (HIV-1). Heteroduplex mobility assay and partial sequence analysis of env and gag genes strongly suggests that all the HIV-infected subjects were infected with clade C HIV-1. Six of eight C-clade HIV-infected individuals elicited CTL activity specific for recombinant vaccinia virus-infected autologous targets expressing HIV gag-pol-env derived from B-clade HIV-1 (IIIB). Recognition of individual recombinant HIV-1 B-clade vaccinia virus-infected targets expressing gag, pol, or env was variable among the patients tested, indicating that cross-clade CTL activity is not limited to a single HIV protein. These data demonstrate that HIV clade C-infected individuals can mount vigorous HIV clade B-reactive CTL responses.

[Localization of ferritin in placental villous tissue and its role in the maternal-fetal iron transport]

OBJECTIVE

To investigate the localization and quantity of ferritin in placental villous tissue and its implications.

METHODS

The localization of ferritin in placental villous tissue at different gestation period was assayed by immunocytochemistry. The quantity of ferritin in placental villous tissue was determined with radioimmunoassay.

RESULTS

Ferritin was localized in all layers of the trophoblast, especially in the surface of the syncytiotrophoblast and basal membrane. The quantity of ferritin in placental villous tissue was increased with gestation progress and decreased in pregnant women with IDA.

CONCLUSIONS

Ferritin may be the important carrier of transplacental iron transport, and its receptor plays a crucial role in the course. The placental iron transport varied with gestation progress and iron nutritional status of the mother.

Differential processing of homologues of the small subunit of ADP-glucose pyrophosphorylase from barley (Hordeum vulgare) tissues

ADP-glucose pyrophosphorylase (AGPase), a two-gene-encoded enzyme, is the key component of starch synthesis in all plants. In the present study, we have used an E. coli expression system for the (over)production of proteins derived from both full length and specifically truncated cDNAs encoding small subunits of AGPase from seed endosperm (AGPase-B1) and leaves (AGPase-B2) of barley (Hordeum vulgare). Based on immunoblot analyses, the molecular mass of the expressed AGPase-B1 (52 kD) was similar to that from endosperm extracts, whereas the expressed AGPase-B2 (56 kD) was larger than that in barley leaves (51 kD). Expression of truncated cDNAs for both the seed and leaf proteins has allowed for a direct verification of molecular masses that were earlier proposed for mature AGPases in barley tissues. The data suggest that seed AGPase-B1 does not undergo any post-translational proteolytic processing in barley, whereas the leaf homologue is processed to a smaller protein. Possible implications of these findings are discussed.

[The study and application of software (LLLZ) connecting the data processing programme with PW1404 X-ray fluorescence spectrometry(I)]

The structure, flow chart, hardware disposition and main function of the software LLLZ, which connecting the data processing programme with the PW1404 X-ray fluorescence spectrometer, was briefly introduced.

Rapid HIV testing and counseling for voluntary testing centers in Africa

OBJECTIVE

Voluntary HIV testing and counseling (VTC) has been shown to reduce the incidence of HIV in cohabiting couples who now represent the majority of new infections in many African cities. Community and client perceptions of a 1-day voluntary testing and counseling program in Lusaka, Zambia, were assessed, and a rapid HIV-testing algorithm was evaluated for VTC centers.

METHODS AND DESIGN

Between May 1995 and June 1996, outreach workers distributed written invitations door to door. The 1-day program was held 6 days/week including weekends. Transport, child care and lunch were provided. Community and client surveys followed in July 1996.

RESULTS

Over 3500 couples married for a median of 4-5 years requested testing: 23% were HIV+/+, 57% were HIV-/- and 20% were discordant with one HIV+ and one HIV- partner. Sixty-eight per cent of couples surveyed had made the decision to be tested before attending the 1-day program and 80% had not previously known where to obtain HIV testing. Knowledge that couples could show discordant results rose from 29 before to 88% after pretest counseling. Clients reported high levels of satisfaction with the services and 90 out of 99 (92%) preferred to receive their results the same day. Clients at another center who waited 10 days for their results reported more fear, and 19 out of 31 (61%) would have preferred to get their results the same day. Over 99% of those who attended the program thought active promotion of voluntary HIV testing in the community was a positive thing, as did 90% of those who were invited but did not attend. Sensitivity and specificity of the rapid test algorithm were both 99.4% in this setting.

CONCLUSIONS

Active promotion of voluntary HIV testing and counseling in couples is needed to reduce the spread of HIV in high-prevalence areas. The use of rapid, on-site HIV testing allows clients to receive result-specific counseling in a single visit. Ongoing quality control of a subset of samples at an outside laboratory is essential.

Evaluation of combined toxic effects of GB/GF and efficacy of jielin injection against combined poisoning in mice

A computer program (Q-test) was used to evaluate the combined toxic effects of nerve agent GF and its combined form with sarin (GB/GF) in mice. Efficacy of Jielin Injection, the 2-PAM-containing antidote used successfully in China for the treatment of organophosphate pesticide poisoning, was also evaluated and compared with HI-6 against single and combined poisonings. The two agents were basically additive in toxicity when combined. However, toxic signs (convulsions) appeared later in combined poisoning than after exposure to each agent alone. The protective ratio of Jielin Injection against GF poisoning was low but significantly higher when against poisoning by GB or combined agent. When HI-6 was substituted for 2-PAM, the antidote was more effective against poisoning by both single and combined agents. Results of in vitro reactivation of GF-inhibited human erythrocyte acetylcholinesterase by these oximes agreed with the in vivo antidotal efficacy.

Radiation response of connexin43-transfected cells in relation to the "contact effect"

Some cell lines grown for only two cell doublings as multicell spheroids develop a form of resistance to killing by ionizing radiation that has been called the "contact" effect. While our previous results have implicated a role for higher order chromatin structure in the contact effect, another possible explanation is the presence of intercellular gap junctions that might facilitate communication between cells grown as spheroids and thereby enhance the ability of cells to resist or recover from radiation damage. To examine the role of gap junctions in the contact effect, rat glioma C6 and mouse EMT6 cell lines were transfected with a gene encoding the gap junctional protein connexin43. While C6 glioma cells are deficient in gap junctional communication, cells from spheroids were nonetheless more resistant than monolayers to killing by ionizing radiation, and the contact effect was present to a similar extent in the three transfected clones. For mouse EMT6 cells, radiosensitivity was similar whether cells were grown as monolayers or spheroids. Transfection of EMT6 cells with connexin43 increased gap junctional communication but did not promote development of a contact effect. Tumor volume doubling time in SCID mice increased significantly for one transfected clone; however, doubling time in vitro was also increased relative to the EMT6 parent. We conclude that extensive gap junctional communication is not a requirement for the increased radiation resistance observed when some cell lines are grown as spheroids.

Cloning and sequence of a gene for the homologue of the stearoyl CoA desaturase from salivary glands of the tick Amblyomma americanum

A 1488 base pair cDNA clone has been isolated from a cDNA library made from salivary glands from 3-day feeding adult female ticks. The sequence of this cDNA suggests it is the gene for the tick homologue of the stearoyl CoA desaturase. This gene is expressed in eggs and all feeding stages of the adult examined, but appears to be transcribed to an 8 kb mRNA as well as a 1.5 kb mRNA. Because ticks have the ability to synthesize monounsaturated fatty acids and demonstrate a large increase in salivary monounsaturated fatty acids during tick feeding, we hypothesize that stearoyl CoA desaturase may be a key enzyme in the morphogenesis of tick salivary glands during feeding.

Temperature-sensitive mutants of Corynebacterium ammoniagenes ATCC 6872 with a defective large subunit of the manganese-containing ribonucleotide reductase

Chemical mutagenesis of the nucleotide-producing strain Corynebacterium ammoniagenes ATCC 6872 with N-methyl-N-nitro-N-nitrosoguanidine followed by an enrichment protocol yielded 46 temperature-sensitive (ts) clones. A rapid assay for the allosterically regulated Mn-ribonucleotide reductase (RRase) was developed with nucleotide-permeable cells of C. ammoniagenes in order to screen for possible defects in DNA precursor biosynthesis at elevated temperature. Three mutants (CH 31, CH 32, and CH 33) grew well at 30 degrees C but did not proliferate at 40 degrees C because they did not reduce ribonucleotides to 2'-deoxyribonucleotides. They were designated nrdts (nucleotide reduction defective). When the cultures were shifted from 30 to 40 degrees C, the nrdts mutants immediately ceased to incorporate radiolabeled nucleic acid precursors into the DNA fraction, while DNA chain elongation was barely affected. Thus, exhaustion of the deoxyribonucleotide pool ultimately inhibited cell division, leading to a filamentous growth morphology. In contrast to the wild-type, all three nrdts mutants displayed a distinctly enhanced sensitivity of ribonucleotide reduction towards hydroxyurea (in permeabilized cells and in vitro) at 30 degrees C. The results from assays for biochemical complementation of heat-inactivated (2 min, 37 degrees C) mutant enzyme with either the small or the large subunit of wild-type Mn-RRase located the mutational defect on the large subunit.

Evidence of ectokinase-mediated phosphorylation of osteopontin and bone sialoprotein by osteoblasts during bone formation in vitro

Osteopontin (OPN) and bone sialoprotein (BSP) are phosphorylated glycoproteins that, together with osteonectin/secreted protein, acidic, rich in cysteine (SPARC) and osteocalcin, comprise the major non-collagen proteins of bone. Although phosphorylation of OPN and BSP, which is known to influence the biological properties of these proteins, has been shown to occur intracellularly, recent studies have demonstrated ectokinase activity in bone cell populations [Mikuni-Takagaki, Kakai, Satoyoshi, Kawano, Suzuki, Kawase and Saito (1995) J. Bone Miner. Res. 10, 231-241]. To determine whether OPN and BSP are phosphorylated by ectokinase activity we have used [gamma-32P]ATP and [gamma-32P]GTP as cell-impenetrable phosphate donors to analyse for ectokinase activity in osteoblastic UMR106.06 cells and fetal rat calvarial cells (FRCCs). By pulse-labelling confluent cells with radiolabelled nucleotides, the phosphorylation of endogenous and exogenously added OPN and BSP was demonstrated together with the labelling of a number of cell surface proteins. These phosphorylation reactions were inhibited by a cell-impermeable ectokinase inhibitor, K252b, and cell surface phosphorylation was also inhibited by exogenously added OPN and BSP substrates, indicating competition for the ectokinase enzyme. However, phosphorylation of OPN and BSP, both of which can mediate cell attachment through Arg-Gly-Asp (RGD) motifs, was not inhibited by an RGD peptide, suggesting that binding of OPN and BSP to cell surface integrins is not required. In similar experiments, ectokinase-mediated phosphorylation of OPN and BSP was demonstrated during mineralized tissue formation by FRCCs in vitro. These studies demonstrate that OPN and BSP secreted by bone cells are phosphorylated by a casein kinase II-like ectokinase present on the surface of osteoblastic cells.

Molecular cloning and expression of the large subunit of ADP-glucose pyrophosphorylase from barley (Hordeum vulgare) leaves

A cDNA clone, blpl14, corresponding to the large subunit of ADP-glucose pyrophosphorylase (AGPase), has been isolated from a cDNA library prepared from leaves of barley (Hordeum vulgare L.). An open reading frame encodes a protein of 503 aa, with a calculated molecular weight of 54815. The derived aa sequence contains a putative transit peptide sequence, required for targeting to plastids, and has a highly conserved positioning of critical Lys residues that are believed to be involved in effector binding. The derived aa sequence shows 97% identity with the corresponding protein from wheat, but only 36% identity with AGPase from E. coli. The blpl14 gene is expressed predominantly in leaves and to a lesser degree in seed endosperm, but not roots, of barley.

[X-ray fluorescence spectrometrlc determination of nine heavy rare earth elements in the enriched mixture of thulium oxide, ytterbium oxide and lutecium oxide by asming thin film technique]

A method for the determination of nine heavy rare earth elements in the enriched mixture of thulium oxide ytterbium oxide and lutecium oxide by XRF method has been studied in this poper. The samples were prepared by ashing thin film. This method is characterized as it is low cost, economic and simple in standards preparation, and standards can be easily preserved. The accuracy and precision of the results were satisfactory for the demands of prodnction.

[An analysis of acute leukemia cells TfR expression in children]

There are a lot of transferrin receptors on the acute leukemia cells. We used the method of "Receptor Radioligand Assay" to determine the numbers of TfR binding sites on leukemia cells from 20 child patients with acute lymphocyte leukemia (ALL) and 9 with acute myeloid leukemia (AML). The results showed the numbers of TfR binding sites of AML cells were higher than those of ALL cells, and the numbers of complete remission group were lower than those of dead or relapse group. This indicated there might be a relationship between the TfR expression and the prognosis.

Characterization of Natronobacterium magadii phage phi Ch1, a unique archaeal phage containing DNA and RNA

A novel archaeal bacteriophage, phi Ch1, was isolated from a haloalkalophilic archaeon Natronobacterium magadii upon spontaneous lysis. The phage-cured strain N. magadii(L13) was used to demonstrate infectivity of phage phi Ch1. The turbid-plaque morphology and the fact that N. magadii cells isolated from plaques were able to produce phage indicated that phi Ch1 is a temperate phage. The phage morphology resembles other members of Myoviridae-infecting Halobacterium species. In solution below 2M NaCl, the phage lost its morphological stability and infectivity. One- and two-dimensional SDS-PAGE of phage particles revealed at least four major and five minor proteins with molecular masses ranging from 15 to 80 kDa and acidic isoelectric points. Southern blot analysis of chromosomal DNA of a lysogenic N. magadii strain showed that phi Ch1 exists as a chromosomally integrated prophage. The phage particles contain both double-stranded, linear DNA (approx. 55 kbp) as well as several RNA species (80-700 nucleotides). Hybridization of labelled RNA fragments to total DNA from N. magadii and phi Ch1 showed that the virion-associated RNA is host encoded. Part of the phage DNA population is modified and restriction analysis revealed evidence for adenine methylation. Phage phi Ch1 is the first virus described for the genus natronobacterium, and the first phage containing DNA and RNA in mature phage particles.

Cloning and sequence of a gene for a homologue of the C subunit of the V-ATPase from the salivary gland of the tick Amblyomma americanum (L)

A 1084 base pair partial cDNA showing similarity to the C subunit of the vacuolar ATPase (V-ATPase) was isolated on a clone from a cDNA library made from salivary glands from 3-day-old feeding adult Amblyomma americanum (L.) female ticks. The 5' end was completed using primer extension and the two pieces joined to form a complete cDNA of 1373 bp. This mRNA is expressed in embryos and the salivary glands of unfed adults and adult females at all stages of feeding. Specific inhibitors of the V-ATPase decrease the rate of dopamine-stimulated secretion of isolated salivary glands, but not as much as ouabain, an inhibitor of the Na+, K+ ATPase, indicating that a V-ATPase may participate in the mechanism of salivary fluid secretion in A. americanum, but the volume of saliva secreted is more dependent on an active Na+, K+ ATPase.