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.

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.

Ozone-induced alterations in glutathione in lung subcompartments of rats and monkeys

The current studies were designed to test two hypotheses: (1) differences in steady-state reduced glutathione levels are responsible for subcompartment differences in susceptibility to acute ozone injury, and (2) elevation of reduced glutathione concentrations accounts for the tolerance to further injury produced by repeated ozone exposure. Glutathione was measured in well-defined subcompartments of the lung of both rats and monkeys to compare alterations occurring in both target (distal trachea and terminal bronchiole) and nontarget areas (lobar bronchus, major daughter, minor daughter bronchus, and parenchyma) of the lung in species that differ in sensitivity to ozone exposure (rat is less susceptible than monkey). Glutathione concentrations were decreased in trachea of rats exposed to 0.4 ppm ozone for 2 h and increased in lobar bronchus and distal bronchiole after 2 h exposure at 1 ppm. In monkey, glutathione levels in most subcompartments were not altered by either 0.4 or 1.0 ppm ozone exposure for 2 h. The exceptions were the major daughter subcompartment (200% of control at 0.4 ppm exposure) and the distal bronchiole (55% of control at 1 ppm exposure). Ninety day ozone exposures (6 h/day x 5 days/week) in rats produced an elevation in glutathione (164% of control value) only in distal bronchiole at the 1 ppm exposure level. In a similar manner, glutathione levels in the distal bronchiole of monkeys exposed for 90 days to 1 ppm O3 were 165% of the corresponding control values. These results suggest the following: glutathione levels in target and nontarget areas of the lung and in susceptible versus less susceptible species are not the primary determinant in the differences observed in ozone toxicity; the response of lung subcompartments to short-term ozone exposure varied depending on airway subcompartment and species; increased glutathione levels may be one reason for adaptation of some airway epithelial cells from rats and monkeys exposed to O3 for long periods; and use of well-defined segments of the lung provides a means of assessing changes in target areas of the lung without dilution from nontarget areas.

Prevalence of hypertension and its trends in Chinese populations

The third nation-wide survey of blood pressure level and hypertension was carried out in China in 1991. In total, 950,356 residents aged > or = 15 years were examined. Sampling population were composed of half urban and half rural from 27 provinces or autonomous regions and three municipalities. The results showed that: (1) the age-adjusted prevalence rate of hypertension (systolic blood pressure > or = 140 mmHg or diastolic blood pressure > or = 90 mmHg) was 11.26% (male 12.15%, female 10.32%) and the definite hypertension rate (systolic blood pressure > or = 160 mmHg or diastolic blood pressure > or = 95 mmHg, or on medication) was 5.29% (male 5.38%, female 5.21%); rate of borderline hypertension was evaluated from 2.82% to 6.15% during the 10-year period from 1979/1980 to 1991; (2) the prevalence rate was progressively increased with age, especially after age 35; prevalence rates were generally higher in men than women before about age 44, however by age 60, women had a higher prevalence of hypertension; (3) a general trend of decrease in prevalence from north-eastern to south-western China was confirmed; (4) there were significantly lower rates in rural than in urban areas. Results of preliminary analysis for prevalence of hypertension among different occupations, nationalities, and educational levels were presented.

Hypertension prevalence and status of awareness, treatment and control in China

A nation-wide survey of blood pressure (BP) and high BP was made in China in 1991, using standardized methods and covering 950,356 men and women aged 15 years and above, from 30 provinces, autonomous regions, and municipalities. The purpose of the study was to estimate the prevalence and the status of awareness, treatment, and control of hypertension. The overall prevalence rate of hypertension defined as systolic BP > or = 140 or diastolic BP > or = 90 mmHg or currently on antihypertensive medication was 13.6%, and was higher in urban (16.3%) than in rural (11.1%) setting. The rate was 6.6% if a BP cut-point of 160/95 mmHg was used. Rates were low in younger age-groups but rose sharply after age 45. The total number of hypertensives in 1990 was estimated to be close to 90 millions. Of all hypertensives, about 1/4 were aware of their high BP, half of these were on medication, and only 3% had their BP controlled. All the rates were higher if the BP cut-point was 160/95 mmHg. Higher rates were found in urban than rural setting and, to a lesser degree, for women than men. In conclusion, hypertension was found to be common in China, and the rates of awareness, drug treatment, and controlled BP were low, indicating an urgent need for developing a national program of treatment and prevention of high BP.

Relationship of cytochrome P450 activity to Clara cell cytotoxicity. IV. Metabolism of naphthalene and naphthalene oxide in microdissected airways from mice, rats, and hamsters

Parenteral administration of naphthalene produces a dose-dependent and tissue-, species-, and cell-selective lesion of murine Clara cells. The rate and stereoselectivity of naphthalene metabolism by microsomal preparations correlate with tissue and species differences in cytotoxicity. Because earlier studies used microsomes obtained from whole tissue, differences in susceptibility of proximal and distal airways could not be related to differences in the metabolic activation or detoxication of naphthalene. Specific subcompartments of the respiratory system, obtained by microdissection, have been used to study the cytochrome P450-dependent metabolism of naphthalene and the epoxide hydrolase/glutathione transferase-dependent metabolism of naphthalene oxide. The rates of naphthalene metabolism were substantially higher in mouse airways than in comparable airways of hamsters or rats. Rates of metabolism were higher in distal airways than in the trachea of all species studied. Metabolism in mouse airways was highly stereoselective, whereas that in hamster and rat tissues was not. Nonciliated cells at all airway levels in mice were heavily labeled with an antibody to cytochrome P450 2F2; little labeling was observed in any portion of rat and hamster lungs. Postmitochondrial supernatants prepared from mouse and hamster airways metabolized racemic naphthalene oxide to diol and glutathione adducts at substantially higher rates than did comparable preparations from rats. Although glutathione levels varied 2-4-fold at different airway levels in the three species studied, levels at the most susceptible site (mouse distal bronchioles) were as high as or higher than those at other, less susceptible, sites. These studies support the view that the rate and stereoselectivity of naphthalene metabolism to naphthalene 1R,2S-oxide catalyzed by cytochrome P450 2F2 are critical determinants in the species-specific and region-selective cytotoxicity of naphthalene in mice. The lack of major differences in the catalytic activity or enantioselectivity of putative detoxication enzymes (epoxide hydrolase or glutathione transferases) between mouse and hamster tissue, combined with data showing that the differences in the metabolic fate of naphthalene oxide in proximal versus distal airways are not dramatic, suggests that the initial epoxidation of naphthalene is an important factor in site-selective toxicity. These studies support the need to use tissue from defined airway levels for studies on the relationship of biochemical and metabolic factors important in cellular injury by lung toxicants, such as naphthalene, where there are dramatic regional differences in susceptibility to injury within the respiratory system.

Evidence for involvement of beta-glucan-binding cell surface lectins in human natural killer cell function

We have studied the effects of yeast cell wall derivatives (zymosan and particulate beta-glucan), on the cytolytic effector function of human natural killer cells. Both zymosan and particulate beta-glucan were found to inhibit the NK-cell-mediated killing of K562, Molt-4, U937, and HL60 tumor cells. Zymosan also inhibited the IL-2-dependent proliferation of NK cells, suggesting that some component of the yeast cell wall delivers a down-modulatory signal affecting multiple NK cell functions. NK cell surface molecules capable of binding both zymosan and Sepharose-immobilized pustulan (linear 1,6-beta-D-glucan, a carbohydrate component of zymosan and particulate beta-glucan) were identified in detergent lysates prepared from surface iodinated NK cells. Our results suggest that NK cells express cell surface beta-glucan-binding lectins that may contribute to NK-cell-mediated natural cytotoxicity.

Dose-dependent tolerance to ozone. IV. Site-specific elevation in antioxidant enzymes in the lungs of rats exposed for 90 days or 20 months

Ozone-induced lung injury in rats is focal, with the primary target sites being the distal trachea and the central acinus. In both area, ozone causes cellular injury and necrosis after short-term exposures, but the areas become tolerant to further injury after long-term exposure. To investigate the role of antioxidant enzymes in the resistance of the lung to injury from long-term ozone exposure, we measured activities of three antioxidant enzymes in airway samples microdissected from specific sites within the lung: distal trachea, lobar bronchi, major daughter axial bronchi, minor daughter bronchi, distal bronchiole, and parenchyma. Fischer 344 rats were exposed to 0, 0.5, and 1 ppm ozone 6 hr/day, 5 days/week for 20 months, or to 0, 0.12, and 1 ppm for 90 days. Glutathione transferase, glutathione peroxidase, and superoxide dismutase activities were measured at the end of the exposure periods. Data were normalized for DNA content (Units/mg DNA). For both the 90-day and 20-month exposures, the activities of all three enzymes were significantly elevated in a concentration-dependent fashion in the distal bronchioles. Compared to controls, animals exposed to 1.0 ppm ozone had superoxide dismutase activities 1.6x (90 days) and 2x (20 months) greater; glutathione peroxidase had activities 1.4x (90 days) and 1.6x (20 months) greater; and glutathione S-transferase had activities 1.5x (90 days and 20 months) greater. In animals exposed for 90 days, superoxide dismutase activity was lower in major daughter bronchi and greater in minor daughter bronchi and glutathione peroxidase activity was lower in major daughter bronchi. After 20 months of exposure, superoxide dismutase activity was significantly elevated in a dose-dependent fashion in the distal trachea; glutathione peroxidase activity decreased in the major daughter bronchi and increased in the minor daughter bronchi; and glutathione S-transferase activity decreased in the major daughter bronchi. There were no changes in antioxidant enzyme levels in other subcompartments. Superoxide dismutase activity increased in a concentration-dependent fashion in the whole lung homogenate of animals exposed for 90 days, but no differences were detected in whole lung homogenates of any other exposure groups. We conclude that (1) antioxidant enzyme activities are altered on a site-specific basis in response to long-term exposure to ozone; (2) the antioxidant enzymes respond differently in different lung subcompartments; (3) activities determined for the whole lung do not reflect changes in subcompartments with variable susceptibility to injury; and (4) changes in antioxidant enzyme activities are concentration-dependent and altered by length of exposure.

Variation in antioxidant enzyme activities in anatomic subcompartments within rat and rhesus monkey lung

Antioxidant enzymes including catalase, superoxide dismutase, glutathione peroxidase, and glutathione S-transferases are thought to be the primary cellular defense against reactive oxygen species. Since pulmonary injury produced by oxidant air pollutants like ozone is highly focal, involving primarily the trachea and centriacinar areas of the lung, measurements of alterations in antioxidant enzyme activities in whole lung may substantially underestimate changes occurring in target areas of the respiratory tract. We have applied a technique for preparation of lung specimens from well-defined anatomic locations to determine whether the focal injury associated with ozone exposure is related to an uneven distribution of antioxidant enzyme activity in the respiratory tract. Our study compared enzyme activities in rat and monkey, species which differ considerably in sensitivity to ozone-induced injury (monkey > rat). The activities of glutathione S-transferase varied less than twofold between different airway subcompartments for both the rat and monkey. Pulmonary veins had approximately 50% of the activity of airways in both species. Glutathione peroxidase activity was slightly higher in proximal compared to distal airways of the rat but was evenly distributed at all airway levels in the monkey. In both species, activity in pulmonary veins was lower than that in airways. The activity of superoxide dismutase was similar in rat and monkey and marked differences were not observed in the various subcompartments studied. Similarly, catalase activity was relatively evenly distributed in rat airways but, in the monkey, the distal bronchiole and lobar bronchus had marginally higher activity than the trachea. We conclude that: (1) measurement of antioxidant enzyme activities in anatomic subcompartments within the lung is feasible using microdissected specimens, (2) antioxidant enzyme activity can vary in different subcompartments of the lung of the same species, (3) the pattern of variation in enzyme activity differs by the enzyme and by species, and (4) species and subcompartment differences in ozone injury are not due primarily to differences in the distribution of antioxidant enzyme activity.

Regeneration of herbicide resistant transgenic rice plants following microprojectile-mediated transformation of suspension culture cells

Suspension cells of Oryza sativa L. (rice) were transformed, by microprojectile bombardment, with plasmids carrying the coding region of the Streptomyces hygroscopicus phosphinothricin acetyl transferase (PAT) gene (bar) under the control of either the 5' region of the rice actin 1 gene (Act1) or the cauliflower mosaic virus (CaMV) 35S promoter. Subsequently regenerated plants display detectable PAT activity and are resistant to BASTA(TM), a phosphinothricin (PPT)-based herbicide. DNA gel blot analyses showed that PPT resistant rice plants contain a bar-hybridizing restriction fragment of the expected size. This report shows that expression of the bar gene in transgenic rice plants confers resistance to PPT-based herbicide by suppressing an increase of ammonia in plants after spraying with the herbicide.

Identification and functional characterization of a TIA-1-related nucleolysin

We recently reported the molecular cloning of a cytotoxic granule-associated RNA-binding protein designated TIA-1. The ability of recombinant TIA-1 to induce DNA fragmentation in permeabilized cells suggested that this protein is the granule component responsible for inducing apoptosis in cytolytic lymphocyte (CTL) targets. Here we report the characterization of a cDNA encoding a TIA-1-related protein designated TIAR. The deduced amino acid sequence of TIAR reveals it to be a 42-kDa protein possessing three RNA-binding domains and a carboxyl-terminal auxiliary domain. Although the RNA-binding domains of TIA-1 and TIAR share greater than 85% amino acid homology, their carboxyl-terminal auxiliary domains are only 51% homologous. The carboxyl terminus of TIAR contains a lysosome-targeting motif, indicating that TIAR is probably a cytotoxic granule-associated protein. Like TIA-1, purified recombinant TIAR induced DNA fragmentation in permeabilized target cells. Although immunoblotting analysis of post-nuclear supernatants revealed TIA-1 protein to be restricted to CTLs, PCR analysis revealed the expression of TIA-1 and TIAR mRNA transcripts in a wide variety of cell types. Our data suggest that the granules of CTLs contain at least two candidate nucleolysins involved in CTL killing.

B-cell maturation in chronic lymphocytic leukaemia. IV. T-cell-dependent activation of leukaemic B cells by staphylococcal enterotoxin 'superantigens'

Staphylococcal enterotoxins (SE) are potent T-lymphocyte activators that stimulate T cells by directly cross-linking HLA-DR molecules on antigen-presenting cells with the V beta gene products of the T-cell receptor. The different SE activate all T cells expressing a given V beta, and, therefore, have been termed 'superantigens'. Here we show that SE are potent activators of leukaemic B cells from patients with chronic lymphocytic leukaemia (CLL). Purified B cells from seven of eight CLL patients with high WBC counts (greater than 80,000/microliters) responded to one or several of the tested SE (SEA, SEB, SEC1, SED, SEE) by proliferation ([3H]TdR incorporation) and/or Ig secretion. In several instances, the response of leukaemic B cells to SE was much stronger than was the response to other known B-cell activators including EBV, pokeweed mitogen (PWM), phorbolester (TPA), and Staphylococcus aureus Cowan I (SAC). The activation of leukaemic B cells by SE was strictly dependent on the addition of irradiated T cells isolated from healthy donors. FACS analysis of cultured cells ensured that the proliferating cells were indeed B cells. Taken together, these results demonstrate that SE are strong T-cell-dependent B-cell activators that, in some cases, can stimulate maturation of leukaemic B cells which are refractory to other activation signals.

Mycorrhizal fungi and nonhydraulic root signals of soil drying

We propose that mycorrhizal colonization of roots alters nonhydraulic root to shoot communication of soil drying. Split-root rose (Rosa hybrida L. cv Samantha) plants-one side of the root system colonized by Glomus intraradices Schenck & Smith, the other side nonmycorrhizal-displayed different stomatal conductances upon partial drying, depending upon whether mycorrhizal or nonmycorrhizal roots were dried. No differences in leaf water status were observed among control plants and those whose mycorrhizal or nonmycorrhizal roots were dried.

Effect of intermolecular orientation upon proton transfer within a polarizable medium

Ab initio calculations are used to investigate the proton transfer process in bacteriorhodopsin. HN = CH2 serves as a small prototype of the Schiff base while HCOO- models its carboxylate-containing counterion and HO- the hydroxyl group of water of tyrosine, leading to the HCOO-..H+..NHCH2 and HO-..H+..NHCH2 complexes. In isolation, both complexes prefer a neutral pair configuration wherein the central proton is associated with the anion. However, the Schiff base may be protonated in the former complex, producing the HCOO-..+HNHCH2 ion pair, when there is a high degree of dielectric coupling with an external polarizable medium. Within a range of intermediate level coupling, the equilibrium position of the proton (on either the carboxylate or Schiff base) can be switched by suitable changes in the intermolecular angle. pK shift resulting from a 60 degrees reorientation are calculated to be some 5-12 pK U within the coupling range where proton transfers are possible. The energy barrier to proton transfer reinforces the ability of changes in angle and dielectric coupling to induce a proton transfer.

[Mechanism of the antiasthmatic effect of total coumarins in the fruit of Cnidium monnieri (L.)Cuss]

Total coumarins in the fruit of Cnidium monnieri show a marked protective effect against bronchial asthma induced by inhalation of histamine in conscious guinea pig. In vitro these total coumarins can relax the contraction of the isolated trachea in guinea pigs induced by histamine as well as increase the perfusion rate of isolated lung preparation of guinea pig. These actions, however, may be blocked by propranolol. Besides, these coumarins cannot increase the heart rate and arterial blood pressure in anesthetized rats. All this shows that the antiasthmatic effect of total coumarins in the fruit of Cnidium monnieri is mediated by beta 2-receptor.