Logic gates and computation from assembled nanowire building blocks

Miniaturization in electronics through improvements in established "top-down" fabrication techniques is approaching the point where fundamental issues are expected to limit the dramatic increases in computing seen over the past several decades. Here we report a "bottom-up" approach in which functional device elements and element arrays have been assembled from solution through the use of electronically well-defined semiconductor nanowire building blocks. We show that crossed nanowire p-n junctions and junction arrays can be assembled in over 95% yield with controllable electrical characteristics, and in addition, that these junctions can be used to create integrated nanoscale field-effect transistor arrays with nanowires as both the conducting channel and gate electrode. Nanowire junction arrays have been configured as key OR, AND, and NOR logic-gate structures with substantial gain and have been used to implement basic computation.

Highly polarized photoluminescence and photodetection from single indium phosphide nanowires

We have characterized the fundamental photoluminescence (PL) properties of individual, isolated indium phosphide (InP) nanowires to define their potential for optoelectronics. Polarization-sensitive measurements reveal a striking anisotropy in the PL intensity recorded parallel and perpendicular to the long axis of a nanowire. The order-of-magnitude polarization anisotropy was quantitatively explained in terms of the large dielectric contrast between these free-standing nanowires and surrounding environment, as opposed to quantum confinement effects. This intrinsic anisotropy was used to create polarization-sensitive nanoscale photodetectors that may prove useful in integrated photonic circuits, optical switches and interconnects, near-field imaging, and high-resolution detectors.

Effect of potassium supplementation on blood pressure in Chinese: a randomized, placebo-controlled trial

OBJECTIVE

To examine the effect of potassium supplementation on blood pressure (BP) in a Chinese population who consume a habitual high sodium and low potassium diet.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Community sample from Beijing, China.

PARTICIPANTS

A total of 150 men and women aged 35-64 years with an initial systolic BP 130-159 mmHg and/or diastolic BP 80-94 mmHg.

INTERVENTIONS

Participants were randomly assigned to take 60 mmol potassium chloride supplement or placebo for 12 weeks.

MAIN OUTCOME MEASURE(S)

BP measurements were obtained at baseline, and at 6 weeks and 12 weeks during the trial, using random-zero sphygmomanometers.

RESULTS

The average baseline urinary excretion of sodium and potassium was 182 mmol/24 h and 36 mmol/24 h. Baseline BP and other measured variables were similar between the potassium supplementation and placebo groups. In the active compared to the placebo treatment group, the urinary excretion of potassium was significantly increased by 20.6 mmol/24 h (P< 0.001) during 12 weeks of intervention. Compared to placebo, active treatment was associated with a significant reduction in systolic BP (-5.00 mmHg, 95% CI: -2.13 to -7.88 mmHg, P < 0.001) but not diastolic BP (-0.63 mmHg, 95% CI: -2.49 to1.23 mmHg, P = 0.51) during 12-week intervention.

CONCLUSION

These data indicate that moderate potassium supplementation resulted in a substantial reduction in systolic BP. Our findings suggest that increased potassium intake may play an important role in the prevention and treatment of hypertension in China.

[The psychological effect of clinical examination on women with tubal infertility]

OBJECTIVE

To comprehend the psychological effects in the course of diagnosis and treatment of infertility on the sexuality, emotional feeling and marriage of women with tubal infertility.

METHODS

The study involved 180 hospitalized patients who were awaiting tube operation from May to September in the year 2000. A survey was made by using questionnaire about sexuality, emotional feeling and marriage after infertility examinations.

RESULTS

The sexual intercourse frequency of 46.2% infertile women decreased and no influences on sexual living satisfaction were confirmed during basal body temperature (BBT) examination. 92.3% to 93.2% of the infertile women were sad after hysterosalpingography(HSG) and laparoscopy. 78.9% of them felt remorse when the result of semen examination was normal. 56.6% of them would choose in vitro fertilization and embryo transfer(IVF-ET); 38.9% of the infertile couples' wedlock would not be stable and 10.5% of them would be divorced in the case of continuing infertility 2 years after tube operation.

CONCLUSION

Sexual intercourse in almost half of the infertile couples decreased during BBT examination. Most infertile women became sad when they were informed of the abnormal results of HSG and laparoscopy and the normal results of semen analysis.

Crystal structures of the maltodextrin/maltose-binding protein complexed with reduced oligosaccharides: flexibility of tertiary structure and ligand binding

The structure of the maltodextrin or maltose-binding protein, an initial receptor for bacterial ABC-type active transport and chemotaxis, consists of two globular domains that are separated by a groove wherein the ligand is bound and enclosed by an inter-domain rotation. Here, we report the determination of the crystal structures of the protein complexed with reduced maltooligosaccharides (maltotriitol and maltotetraitol) in both the "closed" and "open" forms. Although these modified sugars bind to the receptor, they are not transported by the wild-type transporter. In the closed structures, the reduced sugars are buried in the groove and bound by both domains, one domain mainly by hydrogen-bonding interactions and the other domain primarily by non-polar interactions with aromatic side-chains. In the open structures, which abrogate both cellular activities of active transport and chemotaxis because of the large separation between the two domains, the sugars are bound almost exclusively to the domain rich in aromatic residues. The binding site for the open chain glucitol residue extends to a subsite that is distinct from those for the glucose residues that were uncovered in prior structural studies of the binding of active linear maltooligosaccharides. Occupation of this subsite may also account for the inability of the reduced oligosaccharides to be transported. The structures reported here, combined with those previously determined for several other complexes with active oligosaccharides in the closed form and with cyclodextrin in the open form, revealed at least four distinct modes of ligand binding but with only one being functionally active. This versatility reflects the flexibility of the protein, from very large motions of interdomain rotation to more localized side-chain conformational changes, and adaptation by the oligosaccharides as well.

Directed assembly of one-dimensional nanostructures into functional networks

One-dimensional nanostructures, such as nanowires and nanotubes, represent the smallest dimension for efficient transport of electrons and excitons and thus are ideal building blocks for hierarchical assembly of functional nanoscale electronic and photonic structures. We report an approach for the hierarchical assembly of one-dimensional nanostructures into well-defined functional networks. We show that nanowires can be assembled into parallel arrays with control of the average separation and, by combining fluidic alignment with surface-patterning techniques, that it is also possible to control periodicity. In addition, complex crossed nanowire arrays can be prepared with layer-by-layer assembly with different flow directions for sequential steps. Transport studies show that the crossed nanowire arrays form electrically conducting networks, with individually addressable device function at each cross point.

Indium phosphide nanowires as building blocks for nanoscale electronic and optoelectronic devices

Nanowires and nanotubes carry charge and excitons efficiently, and are therefore potentially ideal building blocks for nanoscale electronics and optoelectronics. Carbon nanotubes have already been exploited in devices such as field-effect and single-electron transistors, but the practical utility of nanotube components for building electronic circuits is limited, as it is not yet possible to selectively grow semiconducting or metallic nanotubes. Here we report the assembly of functional nanoscale devices from indium phosphide nanowires, the electrical properties of which are controlled by selective doping. Gate-voltage-dependent transport measurements demonstrate that the nanowires can be predictably synthesized as either n- or p-type. These doped nanowires function as nanoscale field-effect transistors, and can be assembled into crossed-wire p-n junctions that exhibit rectifying behaviour. Significantly, the p-n junctions emit light strongly and are perhaps the smallest light-emitting diodes that have yet been made. Finally, we show that electric-field-directed assembly can be used to create highly integrated device arrays from nanowire building blocks.

[Immortalization of the rabbit mandibular condylar chondrocyte with SV40]

OBJECTIVE

To establish an immortalized cell line of the mandibular condylar chondrocyte (MCC).

METHODS

Reconstructed retroviral vector pLN/SV40 containing the large T antigen and neomycin-resistance genes were transfected into the packaging cells PA317 using lipofectin transfection method. Then the primarily cultured cells derived from mandibular condylar chondrocytes(MCCs) of New Zealand rabbits were infected with the positive retrovirus medium and monoclone was selected with G418. Specific primer of large T antigen was designed and PCR was used to detect the integrating of large T antigen gene. The positive cell clones were subcultured and their growth characteristics were compared with untransfected cells.

RESULTS

10 cell clones of the transduced cells showed the positive gene fragment of 1,196 bp, and 5 of them had been further subcultured for more than 30 passages. One clone of A21 had been passaged for more than 100 times in nearly one and half year, and named immortalized mandibular condylar chondrocyte (IMCC). IMCCs were polygonal-shaped, similar to MCCs; the population doubling time of IMCC and MCC were 30.86 h and 78.95 h respectively. Subculture, freezing and recovering had no effect on cellular shape and proliferation of IMCC.

CONCLUSIONS

An immortalized cell cline derived from the rabbit MCC has been successfully established.

[ATP synthesis by free yeast catalysis coupling hollow fiber ultrafiltration separation]

A novel process for the ATP production employing free yeast catalysis and coupling a hollow fiber module ultrafiltration separation was studied. The experimental results of biocatalyst half-life and operating stability for ultrafiltration showed that the enzymes released from free yeast cell could be cut-off efficiently from the product output stream by hollow fiber membrane. The intercepted percentage of ADH and HK reached more than 95% during the steady running. The efficiency of enzymes utilized was 2.0-2.5 fold as much as that of batch reaction. And the time of yeast cells used repeatedly for ATP synthesis reached 2.5-3.0 batches. Under 0.1 MPa, the ultrafiltrating speed of hollow fiber membrane could keep on a stabilizing value for 11 batches continuously. The continuous operation mode of ATP synthesis simultaneous product ultrafiltration separation could be maintained in higher conversion rate for 5.0 h when the whole system fell in a pseudo-stat where the dilution rate was equal to 0.25 h-1.

[Hostility behavior as risk factor of coronary heart disease]

OBJECTIVE

To explore the relationships between hostility, and the risks of coronary-prone behavior and the clusters of unhealthy behaviors in individuals with different levels of hostility.

METHODS

A cross-sectional study was carried out among 1 010 male employees from two factories in Beijing Capital Steel and Iron Company in 1997. Data on major risks of cardiovascular, other social-demographic factors and levels of hostility by Cook-Medley Scales were collected.

RESULTS

Body mass index, amounts of cigarette smoking and alcohol drinking were significantly increased (P < 0.01) with a characteristic of reduced social support from one's colleagues, when individual's level of hostility increased. In addition, less years of education, higher prevalence of other chronic diseases (P < 0.05) and clustering of various unhealthy behaviors were found related to the increase of individual's hostility. The odds ratio in the group with highest hostility was 2.37 times higher than in the lowest one, after confounding effects from age, blood pressure, education level, status of chronic disease and social support being adjusted. No significant differences on both systolic and diastolic blood pressures among groups with different levels of hostility were discovered.

CONCLUSION

The association between hostility, coronary-prone risk behavior and cluster of unhealthy behaviors suggested that hostility might increase the risk of coronary heart diseases through affecting individual's behavior.

[Effect of yimai jiangya extract on plasma neuropeptide Y level in patients of senile hypertension with qi-deficiency and blood stasis syndrome]

OBJECTIVE

To observe the effect of Yimai Jiangya extract (YMJYE) on plasma neuropeptide Y (NPY) level in patients of senile hypertension at stage II with Qi-Deficiency and blood stasis Syndrome (QDBSS).

METHODS

Sixty-eight patients were randomly divided into two groups, 36 patients in the treated group treated with YMJYE and 32 patients in the control group treated with captopine. Radioimmunoassay was used to examine the level of plasma NPY before and after treatment in the two groups.

RESULTS

Before treatment, plasma NPY level was significantly higher in both groups than that in the old healthy persons (P < 0.01), it lowered significantly after treatment and the decrement was more obvious in the treated group in comparing with that in the control group (P < 0.01). Blood pressure was significantly lowered in both groups after treatment (P < 0.01) but with no significant difference between them.

CONCLUSION

Plasma NPY level was increased in patients of senile hypertension with QDBSS. YMJYE had good effect in lowering plasma NPY level and reducing blood pressure. It is presumed that the NPY lowering effect of YMJYE might be one of its mechanisms in lowering blood pressure.

PCD1, a novel gene containing PDZ and LIM domains, is overexpressed in several human cancers

In an effort to discover novel genes differentially expressed in human pancreatic cancer, we have identified a gene named PCD1 (pancreatic cancer derived) that is up-regulated in pancreatic dysplasia and cancer relative to normal pancreatic ductal epithelium. We cloned the full length (4572 bp) of this gene, which encodes a novel protein of 1064 amino acids containing a PDZ domain and a LIM domain. An alternatively spliced form with a deletion of 30 bp in the coding region was also found. In situ hybridization results showed that PCD1 is highly expressed in a significant percentage of colon, breast, liver, lung, pancreas, stomach, and prostate tumor tissues but is expressed in very few normal tissues. Northern blot hybridization confirmed the overexpression of PCD1 in colon and breast tumor tissues and also showed strong expression of PCD1 in the heart as well as in HeLa cells. Real-time quantitative reverse transcription-PCR verified the overexpression of PCD1 in primary colon tumors or in liver metastases relative to normal colon tissues in five of eight patients. The PCD1 gene maps to human chromosome 13q21.33. Because of its high levels of expression in neoplastic tissues and the presence of both PDZ and LIM domains, we suggest that PCD1 may play an important role in cytoskeletal reorganization during carcinogenesis.

[Allotransplantation of cultured fetal parathyroid gland cells in treating patients with hypoparathyroidism]

OBJECTIVE

To evaluate the therapeutic efficacy of transplantation of cultured human fetal parathyroid gland (chf-PTG) cells in treating patients with primary or secondary hypoparathyroidism.

METHODS

Chf-PTG cells were allotransplanted into the renal adipose capsules of 6 patients with hypoparathyroidism under the ultrasonic guidance. The levels of serum parathyroid hormone (PTH) and calcium were monitored by radioimmunometric assay (RIA) and biochemical method, respectively. Both indexes of pre-and post-operation were compared and the data were analyzed.

RESULTS

The levels of serum PTH and calcium were markedly elevated from three days to the first two weeks following transplantation of chf-PTG cells (P < 0.01). The PTH and calcium levels gradually stabilized from day 14 up to months 9-12, during which the symptoms of the patients alleviated or relieved.

CONCLUSION

The transplantation of chf-PTG cells is a potential method for treating patients with primary or secondary hypoparathyroidism.

[Clinical and experimental study on Shuanghua aerosol in treating infantile upper respiratory tract infection]

OBJECTIVE

To study the effect and mechanism of Shuanghua aerosol (SHA) in treating infantile upper respiratory tract infection (IURTI).

METHODS

In the clinical study, 276 cases of IURTI were randomly divided into two groups. The treated group was treated with SHA and the control group was treated with Shuanghuanglian aerosol (SHLA). In the experimental study, the effect of SHA on anti-inflammatory and anti-viral were observed.

RESULTS

The clinical total effective rate of SHA was 99.03% and its cure rate 65.38%, while those of the SHLA was 94.11% and 44.12% respectively, significant difference was shown between the two groups (P < 0.01). Experimental study showed that SHA could inhibit the xylol induced ear swelling and the egg white induced paw swelling in mice obviously, suppress the proliferation of influenza virus in rat's lung.

CONCLUSION

SHA has obvious anti-inflammatory and anti-viral effect, and has good curative effect in treating IURTI.

[Effect of yimai jiangya extract on platelet activation and fibrinolytic activity and angiotensin II in aged patients with essential hypertension]

OBJECTIVE

To observe the effect of Yimai Jiangya extract (YMJYE) on platelet alpha-granule membrane protein (GMP-140), tissue-type plasminogen activator (t-PA) and its inhibitor (PAI), angiotensin II (AngII) in aged patients with essential hypertension (EH) of stage 2 caused by Qi deficiency and blood stasis.

METHODS

Radioimmunoassay (RIA) and colorimetric analysis were used to examine the levels of GMP-140, t-PA, PAI and AngII before and after treatment with YMJYE in 42 aged patients (treated group), compared with that of 30 aged patients before and after treatment with captopril (control group) and 30 aged healthy subjects (healthy group).

RESULTS

Before treatment, GMP-140, PAI and AngII were significantly higher (P < 0.01), and t-PA were obviously lower (P < 0.01) in the treated and the control group compared with those in the healthy group. After treatment, the improvement of GMP-140, t-PA, PAI and AngII in the treated group were obvious (P < 0.05, P < 0.01). The improvement of GMP-140, t-PA, PAI in the treated group was more significant than that of control group (P < 0.05, P < 0.01), while the improvement of AngII in the treated group was worse than that of the control group (P < 0.01). After treatment, there was insignificant changes about the levels of blood pressure between the treated group and the control group (P > 0.05).

CONCLUSIONS

In the aged patients, GMP-140, PAI and AngII were increased, t-PA reduced. The effects of YMJYE in inhibiting platelet activation and improving fibrinolytic activity were better than that of captopril. These findings indicated that the mechanisms of inhibiting platelet activation and improving fibrinolytic activity and lowering blood pressure of YMJYE were correlated with decreasing the levels of AngII, but other mechanisms may also exist.

Identification of a novel aspartic-like protease differentially expressed in human breast cancer cell lines

Four different human breast cancer cell lines were examined to search for genes associated with tumor growth and metastasis. Each of these cell lines, MDA-MB-453, MCF-7, MDA-MB-231 and MDA-MB-435, displays different phenotypic characteristics ranging from poorly to highly tumorigenic and metastatic. The differences in gene expression profiles of these cell lines generated by differential display technique should allow one to identify candidates as putative oncogenes or tumor/metastasis suppressor genes. A novel cDNA expressed in the highly tumorigenic and metastatic cell line, MDA-MB-435, was identified and isolated by this approach. The function for this gene, designated ALP56 (aspartic-like protease 56 kDa), in tumor progression is suggested by the homology of the encoded protein to aspartic proteases, such as cathepsin D. The amino acid residues in two catalytic domains of this family are highly conserved in those domains of ALP56. Northern hybridization indicated that the expression of ALP56 is associated with growth and metastasis of MDA-MB-435 tumors in immunodeficient mice. In situ hybridization of biopsies from breast cancer and colon cancer patients indicated that ALP56 is upregulated in human primary tumors and liver metastasis. These results suggest that this novel gene correlates with human tumor progression.

[Immunohistochemical study of type I and type II collagen in the remodelling of the supraosseous tissue of mandibular condyle]

OBJECTIVE

Previous studies focused on the pathological changes of the supraosseous tissue of mandibular condyle (STMC), but little is known about extracellular matrix during the remodelling activity of temporomandibular joint (TMJ). This study will examine the characteristics of type I and type II collagen during this process.

METHODS

The animal model was established by extracting the left lower molars of adult rabbits. Temporomandibular joints of two sides were taken after 2 weeks, 1 month and 3 months respectively, and embedded in paraffin. Then 5 microns-thick sections were cut and processed for immunohistochemistry and haematoxylin-eosin staining. An immunohistochemical ABC method was used to determine the local changes of type I and type II collagen. The positive cells were counted in order to analyze quantitative changes.

RESULTS

After loss of teeth from 2 weeks to 3 months, the number and arrangement of chondrocytes changed. Some chondrocyte clusters were also observed in the non-extraction side of TMJ. Most STMC cells stained positively with anti-type I collagen, but weakly in chondrocytes and hypertrophic chondrocytes. On the other hand, type II collagen only existed in chondrocytes and some hypertrophic chondrocytes. The expression of type I collagen decreased after 2 weeks and became stronger after 1 and 3 months, furthermore distributed unevenly in STMC. Some hypertrophic chondrocytes in the non-extraction side showed strong positive staining with anti-type I collagen. Type II collagen in two sides decreased after 2 weeks, then became stronger after 1 and 3 month, but the whole level was less than that of the control group. Expressions of two kinds of collagen were compared between two sides. Type I collagen in the non-extraction side was stronger than that in the extraction side, while type II collagen had an opposite result.

CONCLUSION

Adult rabbits have a limited remodelling ability, and the synthesis and secretion of type I and type II collagen will change when the remodelling is beyond a proper extent, which will lead to impaired resistance and elasticity of fibrocartilage.

[Cost-effectiveness analysis of Beijing Fangshan cardiovascular prevention program in 1992 - 1997]

OBJECTIVE

To determine whether a community-based cardiovascular disease (CVD) intervention program, undertaken over six years, was cost-effective.

METHODS

Based on Beijing Fangshan Cardiovascular Disease Comprehensive Prevention Program, the cost for intervention and expenditure saved from caring for CVD in the communities with intervention from 1992 to 1997 were calculated, and cost-effectiveness analysis was performed using disability-adjusted life years (DALYs) gained as an indicator of effectiveness.

RESULTS

The cost for one DALY gained reduced gradually from 1992 to 1997, with an average ratio of cost to effectiveness of four to one (4:1). It cost annually 1,586.00, 1,380.20, -2,350.80, -905.30, -1,495.60 and -1,766.70 RMB yuan for one life-year saved, from 1992 to 1997 respectively, in a gradually decreasing trend with the increase in length of intervention. After intervention for two years, ratio of cost to effectiveness has become negative since 1994, which meant a positive benefit from intervention. Sensitivity analysis showed that ratio of cost to effectiveness was little sensitive to the changes in discount rate, weight of age and increase in cost of hospitalization for stroke and coronary heart disease, which reflected its reliability.

CONCLUSION

Community-based comprehensive intervention for CVD in rural population is cost-effective.

Crystal structure of the VHS and FYVE tandem domains of Hrs, a protein involved in membrane trafficking and signal transduction

We have determined the 2 A X-ray structure of the 219-residue N-terminal VHS and FYVE tandem domain unit of Drosophila Hrs. The unit assumes a pyramidal structure in which the much larger VHS domain (residues 1-153) forms a rectangular base and the FYVE domain occupies the apical end. The VHS domain is comprised of an unusual "superhelix" of eight alpha helices, and the FYVE domain is mainly built of loops, two double-stranded antiparallel sheets, and a helix stabilized by two tetrahedrally coordinated zinc atoms. The two-domain structure forms an exact 2-fold-related homodimer through antiparallel association of mainly FYVE domains. Dimerization creates two identical pockets designed for binding ligands with multiple negative charges such as citrate or phosphatidylinositol 3-phosphate.

Probing the structure of the PI-SceI-DNA complex by affinity cleavage and affinity photocross-linking

The PI-SceI protein is an intein-encoded homing endonuclease that initiates the mobility of its gene by making a double strand break at a single site in the yeast genome. The PI-SceI protein splicing and endonucleolytic active sites are separately located in each of two domains in the PI-SceI structure. To determine the spatial relationship between bases in the PI-SceI recognition sequence and selected PI-SceI amino acids, the PI-SceI-DNA complex was probed by photocross-linking and affinity cleavage methods. Unique solvent-accessible cysteine residues were introduced into the two PI-SceI domains at positions 91, 97, 170, 230, 376, and 378, and the mutant proteins were modified with either 4-azidophenacyl bromide or iron (S)-1-(p-bromoacetamidobenzyl)-ethylenediaminetetraacetate (FeBABE). The phenyl azide-coupled proteins cross-linked to the PI-SceI target sequence, and the FeBABE-modified proteins cleaved the DNA proximal to the derivatized amino acid. The results suggest that an extended beta-hairpin loop in the endonuclease domain that contains residues 376 and 378 contacts the major groove near the PI-SceI cleavage site. Conversely, residues 91, 97, and 170 in the protein splicing domain are in close proximity to a distant region of the substrate. To interpret our results, we used a new PI-SceI structure that is ordered in regions of the protein that bind DNA. The data strongly support a model of the PI-SceI-DNA complex derived from this structure.

[The diagnostic value of 13C-urea breath test in Helicobacter pylori colonization density and the severity of gastritis]

OBJECTIVE

To evaluate the diagnostic value of (13)C-urea breath test (UBT) in Helicobacter pylori (Hp) colonization density and the severity of gastritis.

METHODS

The diagnostic accuracy of UBT in the diagnosis of Hp infection with reference to histology (HE and Warthin-Starry stain) was analyzed and the UBT results (DOB values) among the groups of gastritis with different degrees of severity were compared.

RESULTS

By using UBT, 96 of 103 patients with Hp -positive histology were detected (sensitivity, 93.2%), the specificity was 89.1%. DOB value in the Hp colonization dense group was significantly higher than in the other groups (low and moderately dense) (P < 0.05). A significant but weak, correlation was found between the DOB values and the colonization density either with (rs = 0.599 0, P < 0.000 1) or without (r(s) = 0.245 7, P = 0.015 8) inclusion of histologically negative patients. In Hp positive patients, DOB values neither in the groups of active gastritis (0 - 3 grade) nor in the groups of chronic gastritis (1 - 3 grade) had no significant difference. There was no correlation between DOB values and severity of inflammatory infiltration.

CONCLUSION

(13)C-UBT has high sensitivity and specificity in the detection of Hp infection. There is significant but weak, correlation between DOB values and the colonization density of Hp. DOB values could not reflect the density of neutrophil and lymphocyte infiltration.

[Analysis of genome character and amino acid residues 2,209 to 2,248 of NS5 A region of hepatitis C virus in relation to the response to interferon therapy]

OBJECTIVE

To observe nucleotide sequence variations and amino acid residues 2,209 to 2,248 of the NS5 A region of hepatitis C virus in relation to interferon therapy in Chinese patients infected with HCV genotype 1b.

METHODS

We collected sera from 22 patients infected with HCV genotype 1b, performed nested RT-PCR using extracted serum RNA from sera, amplified NS5 A region 2,209 to 2,248 and sequenced the PCR product directly. The deduced amino acid sequences were compared with the corresponding region of the HCV-J prototype strain.

RESULTS

Only 4 isolates were intermediate type, and no mutant type was found. In 18 patients treated with IFN-alpha, only 4 were HCV RNA negative at present, No correlation was found between amino acid mutation and IFN response.

CONCLUSION

Variations in the NS5 A region between amino acid residues 2,209 to 2,248 failed to predict IFN response in Chinese patients infected with HCV genotype 1b. IFN may accelerate nucleotide variation but has little influence on amino acid variations.

[A study on the endotoxin and bacterial contamination in reverse osmosis water and dialysis fluids]

OBJECTIVE

To evaluate the endotoxin (ET) and the bacterial contamination in reverse osmosis (RO) water and dialysis fluids for hemodialysis treatment.

METHODS

Specimens of RO water and dialysis fluids were obtained at random from 18 hospitals in Beijing. ET was measured with chromogenic limulus amoeboeyte lysate (LAL) assay. Bacteriologic samples were processed on heterotrophic plate count agar with pour plate technique. The plasma IL-1, IL-6 and TNFalpha were tested with enzyme-linked immunosorbent assay (ELISA).

RESULTS

The level of ET in RO water was 0.116 +/- 0.063 EU/ml, and the culture of bacteria had 2 positive results, both counting 100 CFU/ml. The level of ET was much higher in acid concentrate (Protocol B) than in basic concentrate (Protocol A). The culture of bacteria had 11 positive results in Protocol B concentration with 8 samples equal or higher than 2,000 CFU/ml. The culture of bacteria had only 3 positive results in Protocol A concentration, all being lower than 2,000 CFU/ml. Another investigation showed that the level of ET in dialysis inlet was higher than 0.5 EU/ml in 5 cases of a total of 16. Their plasma IL-1 and TNFalpha levels were significantly increased.

CONCLUSION

Both ET and bacterial contamination exist in RO water and dialysate. It is essential to examine the level of ET and perform bacterial culture, as well as to disinfect RO and dialysate tank at regular intervals in order to reduce pyrogenic reactions.

Mapping of a DNA binding region of the PI-sceI homing endonuclease by affinity cleavage and alanine-scanning mutagenesis

The PI-SceI protein is a member of the LAGLIDADG family of homing endonucleases that is generated by a protein splicing reaction. PI-SceI has a bipartite domain structure, and the protein splicing and endonucleolytic reactions are catalyzed by residues in domains I and II, respectively. Structural and mutational evidence indicates that both domains mediate DNA binding. Treatment of the protein with trypsin breaks a peptide bond within a disordered region of the endonuclease domain situated between residues Val-270 and Leu-280 and interferes with the ability of this domain to bind DNA. To identify specific residues in this region that are involved in DNA binding and/or catalysis, alanine-scanning mutagenesis was used to create a set of PI-SceI mutant proteins that were assayed for activity. One of these mutants, N281A, was >300-fold less active than wild-type PI-SceI, and two other proteins, R277A and N284A, were completely inactive. These decreases in cleavage activity parallel similar decreases in substrate binding by the endonuclease domains of these mutant proteins. We mapped the approximate position of the disordered region to one of the ends of the 31 base pair PI-SceI recognition sequence using mutant proteins that were substituted with cysteine at residues Asn-274 and Glu-283 and tethered to the chemical nuclease FeBABE. These mutational and affinity cleavage data strongly support a model of PI-SceI docked to its DNA substrate that suggests that one or more residues identified here are responsible for contacting base pair A/T(-)(9), which is essential for substrate binding.

Entry of porcine reproductive and respiratory syndrome virus into porcine alveolar macrophages via receptor-mediated endocytosis

Porcine alveolar macrophages (AMphi) are the dominant cell type that supports the replication of porcine reproductive and respiratory syndrome virus (PRRSV) in vivo and in vitro. In order to determine the characteristics of the virus-receptor interaction, the attachment of PRRSV to cells was examined by using biotinylated virus in a series of flow cytometric assays. PRRSV bound specifically to AMphi in a dose-dependent manner. Binding of PRRSV to AMphi increased gradually and reached a maximum within 60 min at 4 degrees C. By confocal microscopy, it was shown that different degrees of PRRSV binding exist and that entry is by endocytosis. Virus uptake in vesicles is a clathrin-dependent process, as it was blocked by the addition of cytochalasin D and co-localization of PRRSV and clathrin was found. Furthermore, by the use of two weak bases, NH4Cl and chloroquine, it was demonstrated that PRRSV uses a low pH-dependent entry pathway. In the presence of these reagents, input virions accumulated in large vacuoles, indicating that uncoating was prevented. These results indicate that PRRSV entry into AMphi involves attachment to a specific virus receptor(s) followed by a process of endocytosis, by which virions are taken into the cell within vesicles by a clathrin-dependent pathway. A subsequent drop in pH is required for proper virus replication.

Nanocrystalline Silver Particles: Synthesis, Agglomeration, and Sputtering Induced by Electron Beam

Nanocrystalline silver particles with an average size of 15 nm have been prepared by reducing Ag(NH3)+2 with N2H4. H2O, with sodium dodecylbenzene sulfate (DBS) used as the stabilizing agent. The influence of DBS in the reaction is discussed. When the so-prepared silver particles were observed in situ under a transmission electron microscope, we observed an agglomeration and sputtering phenomenon induced by the electron beam. The possible reason for agglomeration and sputtering is proposed. Silver crystals of hexagonal shape, ranging from 20- to 120-nm in size, were formed on a copper grid. This phenomenon may offer a useful means of forming small particles. Copyright 1999 Academic Press.

[A histopathological study on Hunan aqueous drainage implantation in rabbit's eye]

Thirty eyes with 15 healthy white New Zealand rabbits subgrouped into two groups: right eye as an experimental group which was implanted Hunan aqueous drainage (HAD) and left eye served as self-control group in which a silicone band 7 mm in width and 7 to 10 mm in length was placed equatorially around the globe. Within 1 to 12 weeks postoperatively, we examined the anterior segment of the globe by the slit lamp microscopy (SLM) and made histopathological observation under light microscope after sacrifice and enucleation of eyeballs in five batches. SLM examination showed that 8 out of 15 eyes in experimental group showed mild or moderate ocular reaction which subsided within 2 to 14 days postoperatively. Histopathological observation revealed no obvious pathological lesions in the uveal tract tissues in the most globes. No foreign body macrophages were found. It indicates that HAD implant is nontoxic and nonallergenic, so it is adaptable for rabbit ocular tissue. The HAD implant can be used in human eyes, too.

Identification of Lys-403 in the PI-SceI homing endonuclease as part of a symmetric catalytic center

Superposition of the PI-SceI and I-CreI homing endonuclease three-dimensional x-ray structures indicates general similarity between the I-CreI homodimer and the PI-SceI endonuclease domain. Saddle-shaped structures are present in each protein that are proposed to bind DNA. At the putative endonucleolytic active sites, the superposition reveals that two lysine (Lys-301 and Lys-403 in PI-SceI and Lys-98 and Lys-98' in I-CreI) and two aspartic acid residues (Asp-218 and Asp-326 in PI-SceI and Asp-20 and Asp-20' in I-CreI) are related by 2-fold symmetry. The critical role of Lys-301, Asp-218, and Asp-326 in the PI-SceI reaction pathway was reported previously. Here, we demonstrate the significance of the active-site symmetry by showing that alanine substitution at Lys-403 reduces cleavage activity by greater than 50-fold but has little effect on the DNA binding activity of the mutant enzyme. Substitution of Lys-403 with arginine, which maintains the positive charge, has only a modest effect on activity. Interestingly, even though the Lys-301 and Lys-403 residues display pseudosymmetry, PI-SceI mutant proteins with substitutions at these positions have different behaviors. The presence of similar basic and acidic residues in many LAGLIDADG homing endonucleases suggests that these enzymes use a common reaction mechanism to cleave double-stranded DNA.

Porcine reproductive and respiratory syndrome virus infection of alveolar macrophages can be blocked by monoclonal antibodies against cell surface antigens

PRRSV has a restricted macrophage tropism. To explore if the difference in susceptibility of porcine alveolar macrophages (PAM) and peripheral blood mononuclear cells (PBMC) to PRRSV is correlated with certain cellular surface antigens which may serve as a virus receptor, polyclonal antibodies against PAM and PBMC were prepared. Anti-PAM but not anti-PBMC antibodies protected PAM from PRRSV infection suggesting that specific receptor(s) may exist on PAM. Furthermore, monoclonal antibodies (MAbs) against putative receptor(s) were produced. Balb/c mice were firstly immune-tolerized with freshly isolated PBMC after which they were immunized with PAM. Two MAbs (41D3 and 41D5) which blocked PRRSV infection of PAM were obtained. MAb 41D3 and 41D5 prevented the attachment of purified PRRSV to PAM. Both MAbs bound to the cellular membrane of PAM but not to that of porcine peritoneal macrophages, PBMC and three porcine cell lines (SK, ST and PK-15) as revealed by flow cytometry. This membrane reactivity correlates well with the susceptibility of these cells to a PRRSV infection. Taken together, these data suggest that MAb 41D3 and 41D5 recognize a potential cellular receptor for PRRSV on PAM.

Relationship of inhaled ozone concentration to acute tracheobronchial epithelial injury, site-specific ozone dose, and glutathione depletion in rhesus monkeys

Acute pulmonary epithelial injury produced by short-term exposure to ozone varies by site within the tracheobronchial tree. To test whether this variability is related to the local dose of ozone at the tissue site or to local concentrations of glutathione, we exposed adult male rhesus monkeys for 2 h to filtered air or to 0.4 or 1.0 ppm ozone generated from 18O2. Following exposure, lungs were split into lobes and specimens were selected by microdissection so that measurements could be made on airway tissue of similar branching history, including trachea, proximal (generation one or two) and distal (generation six or seven) intrapulmonary bronchi, and proximal respiratory bronchioles. One half of the lung was lavaged for analysis of extracellular components. In monkeys exposed to filtered air, the concentration of reduced glutathione (GSH) varied throughout the airway tree, with the proximal intrapulmonary bronchus having the lowest concentration and the parenchyma having the highest concentration. Exposure to 1.0 ppm ozone significantly reduced GSH only in the respiratory bronchiole, whereas exposure to 0.4 ppm increased GSH only in the proximal intrapulmonary bronchus. Local ozone dose (measured as excess 18O) varied by as much as a factor of three in different airways of monkeys exposed to 1.0 ppm, with respiratory bronchioles having the highest concentration and the parenchyma the lowest concentration. In monkeys exposed to 0.4 ppm, the ozone dose was 60% to 70% less than in the same site in monkeys exposed to 1.0 ppm. Epithelial disruption was present to some degree in all airway sites, but not in the parenchyma, in animals exposed to 1.0 ppm ozone. The mass of mucous and ciliated cells decreased in all airways, and necrotic and inflammatory cells increased. At 0.4 ppm, epithelial injury was minimal, except in the respiratory bronchiole, where cell loss and necrosis occurred, and was 50% that found in monkeys exposed to 1.0 ppm ozone. We conclude that there is a close association between site-specific O3 dose, the degree of epithelial injury, and glutathione depletion at local sites in the tracheobronchial tree.

The organization of chemically characterized afferents to the perivascular neuronal groups of the hypothalamic magnocellular neurosecretory system in the rat

The hypothalamic magnocellular neurosecretory system consists of the paraventricular nucleus and supraoptic nucleus and a number of accessory nuclei. There is evidence that each of the accessory nuclei has a preferential source of afferents. Two of the accessory nuclei, namely the nucleus circularis (NC) and the lateral hypothalamic perivascular nucleus (LHPN), are particularly interesting due to their very close relationship with the blood vessels. The NC is composed of small dense clusters of neurons in the medial anterior hypothalamus. The groups of lateral hypothalamic neurons gathering around vascular branches are collectively called the LHPN. Their close topographical relationship with the blood vessels may indicate that the latter may serve as a source of input to these nuclei. As a part of the effort to investigate this issue, the present study examined in these two nuclei the distribution pattern of terminal-like elements containing 11 transmitters/modulators. Only a few, if any, terminal-like elements of the transmitters/modulators studied could be found distributed in the NC proper, although its immediate vicinity could be densely innervated. On the contrary, the LHPN proper was often densely innervated by fibers expressing the examined markers. These terminal patterns were found to be quite different from those of the paraventricular and supraoptic nuclei. The present findings further substantiate the notion of a functional differentiation among the subnuclei of the magnocellular neurosecretory system. The significance of the relationship of these two perivascular nuclei with the blood vessels is discussed.

Identification of a putative receptor for porcine reproductive and respiratory syndrome virus on porcine alveolar macrophages

To identify the receptor which may determine the macrophage tropism of porcine reproductive and respiratory syndrome virus (PRRSV), monoclonal antibodies (MAbs) against porcine alveolar macrophages (PAM) were produced. Two MAbs (41D3 and 41D5) which completely blocked PRRSV infection of PAM were further characterized. It was found that they reduce the attachment of PRRSV to PAM and immunoprecipitate a 210-kDa membrane protein from PAM. This protein was detected on the cell membranes of PAM but not of PRRSV-nonpermissive cells. A colocalization was found between the reactive sites of MAb 41D3 and PRRSV on PAM membranes. All PRRSV-infected cells in tissues of experimentally infected pigs reacted with MAb 41D3. Taken together, all these data suggest that the identified 210-kDa membrane protein is a putative receptor for PRRSV on porcine macrophages.

Amino acid residues in both the protein splicing and endonuclease domains of the PI-SceI intein mediate DNA binding

A structure-based model describing the interaction of the two-domain PI-SceI endonuclease with its 31-base pair DNA substrate suggests that the endonuclease domain (domain II) contacts the cleavage site region of the substrate, while the protein splicing domain (domain I) interacts with a distal region that is sufficient for high affinity binding. To support this model, alanine-scanning mutagenesis was used to assemble a set of 49 PI-SceI mutant proteins that were purified and assayed for their DNA binding and cleavage properties. Fourteen mutant proteins were 4- to >500-fold less active than wild-type PI-SceI in cleavage assays, and one mutant (T225A) was 3-fold more active. Alanine substitution at two positions in domain I reduces overall binding >60-fold by perturbing the interaction of PI-SceI with the minimal binding region. Conversely, mutations in domain II have little effect on binding, reduce binding to the cleavage site region only, or affect binding to both regions. Interestingly, substitutions at Lys301, which is part of the endonucleolytic active site, eliminate binding to the cleavage site region but permit contact with the minimal binding region. This experimental evidence demonstrates that the protein splicing domain as well as the endonuclease domain is involved in binding of a DNA substrate with the requisite length.

p53 protein expression in patients with hepatocellular carcinoma from the high incidence area of Guangxi, Southern China

Mutation of the p53 gene has been reported in hepatocellular carcinoma (HCC) occurring worldwide. The most frequent p53 mutation has been found in HCCs in regions with high hepatitis B virus (HBV) infection and intake of aflatoxin B1 (AFB1). The aim of our study was to examine p53 protein expression in HCCs from a high incidence area of Guangxi, Southern China, where HBV infection and dietary intake of AFB1 are high. Immunohistochemical staining of p53 protein was carried out using a polyclonal rabbit antibody (CM-1). Serial sections were also stained for hepatitis B surface antigen and core antigen. p53 Protein expression was detected in 13 (43.3%) of the 30 HCCs. Expression of p53 was found in 25.0% (1/4) of the < or = 5.0 cm diameter HCCs, in 36.8% (7/19) of the 5.1-10.0 cm diameter HCCs and in 71.4% (5/7) of the >10.0 cm diameter HCCs. Expression of p53 was observed more in moderately and poorly differentiated than in the well differentiated HCCs and more frequently seen in HCCs from younger patients. These data indicate that there is a close association between p53 protein expression and tumor size, histological grade and age of patients. Twenty-seven out of 30 cases (90.0%) were positive for HBV. No significant association between p53 expression and sex. HBV infection, cirrhosis or alpha-fetoprotein has been found.

[Ocular echographic evaluation of human aqueous drainage implant]

OBJECTIVE

To determine after implantation of a glaucoma aqueous drainage device whether fluid is present around the equatorial plate and to measure the bleb size around the plate.

METHODS

41 plates in 41 patients (41 eyes) with refractory glaucoma who had undergone human aqueous drainage (HAD) implantation underwent standardized echography (both A- and B-scan examinations) after a mean postoperative follow-up period, 5.2 months. According to the bleb height and the fluid underlying and/or overlying the plate, the blebs were divided into five grades and two types to evaluate their functions.

RESULTS

Of the 41 cases examined with echography, 35 (85%) were associated with posterior blebs, 2 (5%) had no associated posterior blebs, and the posterior bleb in 4 (10%) cases was not certain. The percentage of the presence of filtering bleb around the plate was 15%, 12%, 29%, 37%, and 7% in Grade 0 to IV group, and 11% and 89% in type A and B, respectively. There was no significant correlation between the bleb size and the level of intraocular pressure control.

CONCLUSION

Standardized ocular echography is helpful in the postoperative management of failed cases who have undergone HAD implantation because it can demonstrate the presence or absence of blebs and characterize them.

Short-term clinical study on a new aqueous humor drainage implant for refractory glaucoma

OBJECTIVE

To investigate the therapeutic effect of a new aqueous humor drainage (HAD) implant made in China for the treatment of refractory glaucoma.

METHODS

The implant was designed by ourselves and manufactured by Beijing Rubber Products Design and Research Institute. From July, 1993 to September, 1995, we observed 40 patients (41 eyes) with refractory glaucoma treated by implantation surgery, including 16 eyes with neovascular glaucoma (NVG) and 25 eyes with non-neovascular glaucoma (NNVG).

RESULTS

The mean period of postoperative follow-up was 9.2 (range, from 3-27) months, the intraocular pressure (IOP) was lowered from preoperative 7.20 +/- 1.51 kPa to postoperative 2.40 +/- 1.33 kPa in NVG group and from preoperative 6.27 +/- 1.07 kPa to postoperative 2.00 +/- 2.93 kPa in NNVG group. The success rate was 81% in NVG group and 84% in NNVG group. The common postoperative complications were flat anterior chamber, hyphema and choroidal detachment.

CONCLUSIONS

Our newly designed aqueous humor drainage implant is an economical implant in China and one of the alternative and effective methods for the treatment of refractory glaucoma. It can be widely used in clinics.

[Assessment of nutrition in dialysis patients and chronic uremic patients]

Multiple methods were used to assess the nutritional status of 40 uremic non-dialysis or dialysis patients in order to improve their living quality as well as to provide scientific basis for nutritional treatment. The investigation of diet diaries revealed that the ratio of animal protein over total protein in food was greater in uremic dialysis patients treated with either hemodialysis or peritoneal dialysis than in the uremic non-dialysis patients (P < 0.01, P < 0.05); the daily intake of total protein in each of three groups was lower than the recommended amount. The anthropometric measurement showed: decreased muscle protein store occurred in 35% of the dialysis patients and 80% of the uremic non-dialysis patients. Serum albumin measurement revealed that hemodialysis patients had much higher level than that of peritoneal dialysis patients (P < 0.01). 50% of the hemodialysis patients, 80% of the peritoneal dialysis patients and 60% of the uremic non-dialysis patients had lower level of serum albumin than normal. Evaluation of nutritional status of hemodialysis patients and peritoneal dialysis patients by means of urea production found that 65% of the hemodialysis patients and 37.5% of the peritoneal dialysis patients were in a status of negative nitrogen balance. According to the results of all the measurements, 58% of the dialysis patients had malnutrition of various degrees.

Crystal structure of PI-SceI, a homing endonuclease with protein splicing activity

PI-Scel is a bifunctional yeast protein that propagates its mobile gene by catalyzing protein splicing and site-specific DNA double-strand cleavage. Here, we report the 2.4 A crystal structure of the PI-Scel protein. The structure is composed of two separate domains (I and II) with novel folds and different functions. Domain I, which is elongated and formed largely from seven beta sheets, harbors the N and C termini residues and two His residues that are implicated in protein splicing. Domain II, which is compact and is primarily composed of two similar alpha/beta motifs related by local two-fold symmetry, contains the putative nuclease active site with a cluster of two acidic residues and one basic residue commonly found in restriction endonucleases. This report presents prototypic structures of domains with single endonuclease and protein splicing active sites.

Virus quantification and identification of cellular targets in the lungs and lymphoid tissues of pigs at different time intervals after inoculation with porcine reproductive and respiratory syndrome virus (PRRSV)

Sixteen 6 week old conventional pigs were inoculated by aerosol with a European strain of porcine reproductive and respiratory syndrome virus (PRRSV). Virus replication was followed by virus titration and immunofluorescence in the lungs and in associated and distant lymphoid tissues at 3, 14, 21, 35, 42 and 82 days post-inoculation (DPI). PRRSV replication was detected in alveolar macrophages, lungs, tonsils, spleen, retropharyngeal lymph nodes, bronchial lymph nodes and thoracic aortic lymph nodes at 3 DPI. The same tissues, except retropharyngeal and thoracic aortic lymph nodes, were PRRSV positive at 14 DPI. Lungs and alveolar macrophages were PRRSV positive until 35 DPI. PRRSV was not detected in heart, peripheral blood mononuclear cells and bone marrow cells. Viremia was detected from 3 to 28 DPI. Not more than 2% of alveolar macrophages were PRRSV positive even during the acute stage of infection. 80 to 94% of the PRRSV infected cells in the lungs and in lung lavaged cells were identified as macrophages using a porcine macrophage specific monoclonal antibodies. In the lymph nodes and spleen, 100% of the infected cells were macrophages. Anti-PRRSV antibodies were detected by a blocking ELISA as early as 7 DPI. the antibody titre gradually increased to reach a geometric mean titre (GMT) of 160 at 35 DPI. It remained at that level until the end of the study. These findings clearly demonstrate that PRRSV has a tropism for macrophages. PRRSV mainly replicates in macrophages of the lymphoid tissues and lungs in the acute phase of infection and persists in the lung macrophages.

[A short-term clinical study on a new aqueous humor drainage implant for refractory glaucoma]

OBJECTIVE

To investigate the therapeutic effect of a new aqueous humor drainage implant made in China for treatment of refractory glaucoma.

METHODS

The implant was designed by ourselves and manufactured by Beijing Rubber Products Design & Research Institute. From July 1993 to September 1995, we observed 40 cases (41 eyes) with refractory glaucoma treated with the implantation surgery, including neovascular glaucoma (NVG) 16 eyes, non-neovascular glaucoma (NNVG) 25 eyes.

RESULTS

The mean period of postoperative follow-up was 9.2 (range 3-27 months) months, the IOP was lowered from preoperative 7.20 +/- 1.51 kPa to postoperative 2.40 +/- 1.33 kPa in NVG group and from preoperative 6.27 +/- 1.07 kPa to postoperative 2.00 +/- 2.93 kPa in NNVG group. The success rate was 81% in NVG group and 84% in NNVG group. The common postoperative complications were flat anterior chamber, hyphema, choroidal detachment and so on.

CONCLUSIONS

Our newly designed aqueous humordrainage implant provides an economic implant in China. The method of implantation is simple, is one of the effective methods for treatment of refractory glaucoma and can be widely used in clinics.

[The development of a laser back-scattering erythrocyte-aggregometer]

In this paper, an erythrocyte-aggregometer based on the analysis of the light intensity back-scattered by a blood suspension is presented and described in detail. It allows to approach aggregation phenomenon in terms of kinetics, structural and rheological parameters. A personal computer and a microcomputer are applied to automate the system's sampling, data-processing and data-restoring procedure.

Effects of origin and state of differentiation and activation of monocytes/macrophages on their susceptibility to porcine reproductive and respiratory syndrome virus (PRRSV)

In this study, the susceptibility of porcine peripheral blood monocytes (BMo), peritoneal macrophages (PM phi) and alveolar macrophages (AM phi) to PRRSV was examined. To test the effect of differentiation and activation on their susceptibility, AM phi and BMo were aged, cultivated in either adhesion or suspension and treated with bacterial lipopolysaccharide (LPS) and phorbol myristate acetate (PMA). It was found that freshly isolated PM phi and BMo were non-permissive to PRRSV. PM phi remained refractory but a few BMo became susceptible after 1 day cultivation. AM phi were permissive with a significant increase of their susceptibility after one day cultivation. In a binding assay, it was demonstrated that the attachment of biotinylated PRRSV to AM phi is much more efficient than to PM phi and BMo. Two monoclonal antibodies (Mabs) 41D3 and 41D5 which block PRRSV infection of AM phi and are directed against a candidate receptor for PRRSV only reacted with the cell membrane of AM phi. PMA treatment of AM phi blocked PRRSV replication in the cells in a dose-dependent manner. The blocking effect of PMA decreased after 9 h continuous pre-treatment and diminished after 24 h continuous pre-treatment. PMA treatment did not affect the binding of PRRSV and MAb 41D3 and 41D5 to AM phi. Direct or indirect treatment of AM phi and BMo with LPS or cultivation in suspension did not significantly affect their susceptibility. These results provide clear evidence that PRRSV has a strongly restricted tropism for only some sub-populations of porcine monocytes/macrophages and that some specific states of differentiation and activation of monocytes/macrophages considerably affect their susceptibility.

Rates of glutathione synthesis in lung subcompartments of mice and monkeys: possible role in species and site selective injury

Injury to pulmonary epithelial cells from chemicals that undergo P450-dependent metabolic activation and from gases such as ozone is highly focal. These studies examined the rates of glutathione resynthesis in pulmonary subcompartments (trachea, minor daughter/respiratory bronchiole and parenchyma) of mice and monkeys to determine whether differences in glutathione synthesis are partly responsible for wide regional/species variations in susceptibility of the lung to insult. Glutathione levels remained unchanged in lung subcompartments incubated for up to 4 hr in Waymouth's medium. Glutathione levels decreased less than 30% in 4-hr incubations of monkey airways in medium devoid of sulfur amino acids although in mouse airways decreases of 40 to 60% were observed. Diethyl maleate depleted glutathione in lung subcompartments in vitro by varying amounts depending on the species and subcompartment examined. Airways incubated in the presence of cysteine but not methionine or glutathione regenerated glutathione rapidly after diethyl maleate depletion. The rates of regeneration differed significantly with species and airway level. In all airways of the monkey, glutathione levels returned to the initial level within 2 to 4 hr after addition of cysteine containing medium although in mice recovery of glutathione required only 1 (minor daughter and parenchyma) or 2 hr (trachea) incubation with cysteine supplemented medium. These studies show striking species and airway level differences in the rates of glutathione resynthesis and suggest that focal injury to respiratory epithelium may, in part, be mediated by regional differences in the ability to supply glutathione for protection against electrophiles and reactive oxygen species.

Transgenic rice plants harboring an introduced potato proteinase inhibitor II gene are insect resistant

We introduced the potato proteinase inhibitor II (PINII) gene (pin2) into several Japonica rice varieties, and regenerated a large number of transgenic rice plants. Wound-inducible expression of the pin2 gene driven by its own promoter, together with the first intron of the rice actin 1 gene (act1), resulted in high-level accumulation of the PINII protein in the transgenic plants. The introduced pin2 gene was stably inherited in the second, third, and fourth generations, as shown by molecular analyses. Based on data from the molecular analyses, several homozygous transgenic lines were obtained. Bioassay for insect resistance with the fifth-generation transgenic rice plants showed that transgenic rice plants had increased resistance to a major rice insect pest, pink stem borer (Sesamia inferens). Thus, introduction of an insecticidal proteinase inhibitor gene into cereal plants can be used as a general strategy for control of insect pests.

Expression of a Late Embryogenesis Abundant Protein Gene, HVA1, from Barley Confers Tolerance to Water Deficit and Salt Stress in Transgenic Rice

A late embryogenesis abundant (LEA) protein gene, HVA1, from barley (Hordeum vulgare L.) was introduced into rice suspension cells using the Biolistic-mediated transformation method, and a large number of independent transgenic rice (Oryza sativa L.) plants were generated. Expression of the barley HVA1 gene regulated by the rice actin 1 gene promoter led to high-level, constitutive accumulation of the HVA1 protein in both leaves and roots of transgenic rice plants. Second-generation transgenic rice plants showed significantly increased tolerance to water deficit and salinity. Transgenic rice plants maintained higher growth rates than nontransformed control plants under stress conditions. The increased tolerance was also reflected by delayed development of damage symptoms caused by stress and by improved recovery upon the removal of stress conditions. We also found that the extent of increased stress tolerance correlated with the level of the HVA1 protein accumulated in the transgenic rice plants. Using a transgenic approach, this study provides direct evidence supporting the hypothesis that LEA proteins play an important role in the protection of plants under water-or salt-stress conditions. Thus, LEA genes hold considerable potential for use as molecular tools for genetic crop improvement toward stress tolerance.