How does light regulate chloroplast enzymes? Structure-function studies of the ferredoxin/thioredoxin system

1. Introduction 68

2. Ferredoxin reduction by photosystem I 72

3. Ferredoxins 73

4. Ferredoxin[ratio ]thioredoxin reductase 73

4.1 Spectroscopic investigations of FTR 76

4.2 The three-dimensional structure of FTR from the cyanobacterium Synechocystis sp. PCC6803 77

4.2.1 The variable subunit 77

4.2.2 The catalytic subunit 81

4.2.3 The iron–sulfur center and active site disulfide bridge 82

4.2.4 The dimer 84

4.3 Thioredoxin f and m 85

4.4 Ferredoxin and thioredoxin interactions 86

4.5 Mechanism of action 88

4.6 Comparison with other chloroplast FTRs 92

5. Target enzymes 95

5.1 NADP-dependent malate dehydrogenase 95

5.1.1 Regulatory role of the N-terminal extension 97

5.1.2 Regulatory role of the C-terminal extension 99

5.1.3 Thioredoxin interactions 101

5.2 Fructose-1,6-bisphosphatase 101

5.3 Redox regulation of chloroplast target enzymes 103

6. Conclusion 103

7. Acknowledgements 104

8. References 104

A pre-requisite for life on earth is the conversion of solar energy into chemical energy by photosynthetic organisms. Plants and photosynthetic oxygenic microorganisms trap the energy from sunlight with their photosynthetic machinery and use it to produce reducing equivalents, NADPH, and ATP, both necessary for the reduction of carbon dioxide to carbohydrates, which are then further used in the cellular metabolism as building blocks and energy source. Thus, plants can satisfy their energy needs directly via the light reactions of photosynthesis during light periods. The situation is quite different in the dark, when these organisms must use normal catabolic processes like non-photosynthetic organisms to obtain the necessary energy by degrading carbohydrates, like starch, accumulated in the chloroplasts during daylight. The chloroplast stroma contains both assimilatory enzymes of the Calvin cycle and dissimilatory enzymes of the pentose phosphate cycle and glycolysis. This necessitates a strict, light-sensitive control that switches between assimilatory and dissimilatory pathways to avoid futile cycling (Buchanan, 1980, 1991; Buchanan et al. 1994; Jacquot et al. 1997; Schürmann & Buchanan, 2000).

Effect of intragastric pH on control of peptic ulcer bleeding

BACKGROUND

We have performed series studies to investigate the effect of intragastric pH on control of peptic ulcer bleeding. In laboratory and animal studies, both platelet aggregation and gastric mucosal bleeding time were shown to be extremely sensitive to different pH levels. Platelet aggregation decreased significantly at pH > or = 6.8 and gastric mucosal bleeding time fell significantly at pH > or = 6.4. In a prospective clinical trial, primed infusions of different dosages of omeprazole (8 or 4 mg/h) after a bolus (40 mg) produced consistently high intragastric pH values in patients with bleeding duodenal ulcer. These results were not significantly different from that obtained from omeprazole 40 mg bolus treatment every 12 h (P > 0.05). However, primed injection with cimetidine (800 mg/12 h) was less effective (P < 0.05).

METHODS

In a retrospective analysis, 303 patients with bleeding peptic ulcer who were treated with cimetidine and 326 patients who were treated with omeprazole were compared.

RESULTS

The emergency surgery (4.91%) and mortality rates (1.84%) in the omeprazole group were not significantly different (P > 0.05) from those (7.28 and 1.99%) in the cimetidine group. However, the standardized emergency surgery rate of the omeprazole group (3.28%) was significantly lower than that (9.28%) of the cimetidine group (P < 0.05).

CONCLUSION

We conclude that increased intragastric pH to at least 6.4 with omeprazole is helpful in controlling peptic ulcer bleeding. Chinese patients require a lower dose of omeprazole than their Western counterparts to control ulcer bleeding.

[The effective dielectric function of porous SiO2 glass]

In this paper, we discussed the effective dielectric function of porous SiO2 glass with pore size 7.5 nm. We briefly discussed different formulae proposed by different theoretical models of porous systems, and compared the relationship of effective dielectric functions changing with different porosity of porous SiO2 of each formula. Through comparing the experimental spectra and the theoretical spectra of each formula, we found the equation ln epsilon e = theta 1 ln epsilon 1 + theta 2 + theta 2 ln epsilon 2 best indicates the effective dielectric function of porous SiO2. This work is helpful in selecting special absorption materials.

Redox signaling in chloroplasts: cleavage of disulfides by an iron-sulfur cluster

Light generates reducing equivalents in chloroplasts that are used not only for carbon reduction, but also for the regulation of the activity of chloroplast enzymes by reduction of regulatory disulfides via the ferredoxin:thioredoxin reductase (FTR) system. FTR, the key electron/thiol transducer enzyme in this pathway, is unique in that it can reduce disulfides by an iron-sulfur cluster, a property that is explained by the tight contact of its active-site disulfide and the iron-sulfur center. The thin, flat FTR molecule makes the two-electron reduction possible by forming on one side a mixed disulfide with thioredoxin and by providing on the opposite side access to ferredoxin for delivering electrons.

[New coleopterancidai strains of Bacillus thuringiensis and production of coleopterancide]

Two coleopterancidal strains of Bacillus thuringiensis, YM-03 and SHQ11-10, were isolated from soil in China. H-Serotype of YM-03 was H8a8b, and H-Serotype of SHQ11-10 has not been identified. Both of them produced flat bipyramid-like crystals which consisted of 68-70 kD and 65 kD protein respectively. Bioassay indicated that these two Bt strains were very active on the larva of Leptinotarsa decemlineata and Plagioder aversicolora. They grew prosperously in fermentation. Powder of YM-03 product was high effect against colorado potato beetle in the field experiment.

[The immunohistochemistry and clinic study on surgical margin of laryngeal cancer]

OBJECTIVE

To probe into the safe incisal range of removing laryngectomy cancer determined from the albumen balance of cells.

METHOD

LSAB or SABC of immunohistochemistry was applied, and three groups of samples with cancer tissue, nearby cancer tissue and distal cancer tissue of 36 primary laryngectomy cancer were tested by antibodies p16, p21, TGF-beta 1, PCNA and EGFR.

RESULT

The difference of the positive rate with the five antibodies between the cancer group and the two side incisal group were very notable with P < 0.01 or P < 0.05, but which between nearby cancer tissue and distal cancer tissue were not notable with P > 0.05. The differences of the positive rates with 5 antibodied between high differentiation group and low differentiation group were notable with P < 0.05, and P < 0.05 with PCNA in the group whether the lymphonodi cervicales transmitted or not. The incisals for all the cases are beyond 5 mm, the recurerence rate is 3%.

CONCLUSION

The 5 mm incisal for laryngectomy cancer is appropriate on the albumen cevel of cells.

Validity of echocardiographic measurement in an epidemiological study. Project HeartBeat!

In Project HeartBeat!, a longitudinal study of cardiovascular disease risk factors in healthy children and adolescents, 3 samples of 40, 80, and 182 echocardiograms, respectively, were randomly selected and reread to evaluate intraobserver and interobserver variabilities and comparability between measurements of field echocardiographic technicians and reference readings at Texas Children's Hospital. Included in the evaluation were 8 M-mode echocardiographic measurements, ie, aortic root diameter, left atrial diameter, and end-diastolic and end-systolic measurements of interventricular septal thickness, left ventricular (LV) diameter, and LV posterior wall thickness; 8 Doppler measurements; and a calculated LV mass. Means and SDs of the differences of the paired measurements were used to assess the relative bias and random error of the measurements. For the intraobserver comparison, means and SDs of the differences were very small, indicating that the echo measurements were performed consistently by each project echo technician. Interobserver comparison showed statistically but not clinically significant differences between the paired readings of end-diastolic septal thickness, end-systolic LV posterior wall thickness, and 5 Doppler measurements. Comparison with reference readings at Texas Children's Hospital showed significant differences in diastolic LV diameter, systolic septal thickness, and right ventricular ejection time. These differences, however, were minimal with limited clinical significance. Mean differences in LV mass for the corresponding comparisons were -1.82, 4.50, and 0.0013 g, and the SDs were 18.79, 24.16, and 12.35 g, respectively. We conclude that the echocardiographic measurements taken from healthy children in a longitudinal study can be made accurately with acceptable reproducibility.

[The clinical significance of preserving superior epigastric vessels in Cohen incision]

OBJECTIVE

To study the clinical significance of preserving epigastric vessels in Cohen incision.

METHODS

42 cases of pregnant women were performed cesarean section using Cohen incision. One side vessel of incision was preserved, the other side was cut off. By self control comparison, skin temperature of two sides incision has been taken by CET (computer electric infrared thermograph) on the third day post operation. The thinkness of scar was measured with vernier calipers on the 40th day post operation.

RESULTS

The skin temperature difference between both sides of incision was (0.098 +/- 0.088) degree C. On the cut side the skin temperature was higher than that of the other side (P < 0.01). The scar thickness of cut side was (3.61 +/- 0.61) mm, the other side was (3.10 +/- 0.68) mm. The difference was significant (P < 0.01).

CONCLUSION

The inflammatory reaction and formation of scar can be decreased by means of preserving superior epigastric vessels in Cohen incision.

Colloidal bismuth pectin: an alternative to bismuth subcitrate for the treatment of Helicobacter pylori--positive duodenal ulcer

BACKGROUND

Bismuth triple therapy provides consistently good results in Helicobacter pylori eradication worldwide, whereas quadruple therapy using a combination of omeprazole and bismuth triple regimen has produced cure rates in excess of 90%. The prevalence of metronidazole-resistant strains was 26.8% in our area. Colloidal bismuth pectin (CBP) is a new, lower-priced bismuth salt made in China. The purpose of this study was to investigate the efficacy and safety of CBP triple and quadruple regimens in the treatment of H. pylori-positive duodenal ulcer.

MATERIALS AND METHODS

In this prospective trial, 205 patients with H. pylori-positive duodenal ulcer were allocated randomly to receive one of four regimens: metronidazole, 200 mg; amoxicillin, 250 mg; and colloidal bismuth subcitrate (CBS), 120 mg (group 1), or CBP, 100 mg qid (group 2) for 2 weeks, then continued CBS, 240 mg, or CBP, 200 mg bid for a further 2 weeks. A quadruple regimen using a combination of omeprazole, 20 mg bid, and CBS triple therapy (group 3) or CBP triple therapy (group 4), respectively, was given to patients for 1 week, followed by omeprazole, 20 mg once daily for a further 3 weeks. Further endoscopy was performed at least 4 weeks after cessation of the treatment. H. pylori status was determined by histology, a 14C urea breath test, and a urease test.

RESULTS

The per-protocol H. pylori cure rates were 85% (22 of 26 patients), 90% (35 of 39), 96% (46 of 48), and 95% (75 of 79) for groups 1 through 4. In the intention-to-treat analysis, cure rates were 79% (22 of 28), 83% (35 of 42), 90% (46 of 51), and 89% (75 of 84), respectively. The cure rates of quadruple therapy were higher than those of triple therapy; an 8.2% difference was not statistically significant (95% confidence interval [CI], 2.3-18.7%). The ulcer-healing rates were 88%, 87%, 98%, and 97%, respectively, for groups 1 through 4. The ulcer pain was relieved more rapidly in quadruple- than in triple-therapy regimens. Two patients discontinued treatment prematurely owing to drug-related side effects.

CONCLUSION

One-week quadruple therapy is highly effective and safe in H. pylori eradication in Chinese patients. CBP is as effective as CBS.

[The two-step three-photon resonant ionization of atom Cu]

This paper discusses the process of resonant laser ablation (RLA), where the two-step three-photon resonant ionization of copper is considered as the best scheme. The rate equations of resonant ionization of copper are calculated and the factors that affect the ionization efficiency are discussed. The results prove the potential advantages of RLA especially the low energy threshold.

[The identification of 5 new serotypes of Bacillus thuringiensis from soil in China]

Five new strains of Bacillus thuringiensis(Bt) from soil in China were classified. 5 new H-serotypes: H42, H43, H56, H60 and H62 were identified. There were some distinction in the morphology, biochemical reaction and toxicity against species of insect. Five new Bt subspecies were identified as follows: Strain YGd22-03 Bacillus thuringiensis subsp. jinghongiensis, H42; Strain KK31-01 Bacillus thuringiensis subsp. guiyangiensis, H43; Strain SCg04-02 B. thuringiensis subsp. rongseni, H56; Strain NXP15-04 B. thuringiensis subsp. pingluonsis, H60; Strain HZ39-04 B. thuringiensis subsp. zhaodongensis, H62.

Apolipoprotein E affects serial changes in total and low-density lipoprotein cholesterol in adolescent girls: Project HeartBeat!

Apolipoprotein E (apo E) polymorphism is a genetic determinant of lipid and lipoprotein levels and the risk for coronary heart disease. The extent to which serial patterns of change in total cholesterol and low-density lipoprotein cholesterol (LDL-C) concentrations varied by apo E genotype was therefore investigated in 247 Caucasian girls aged 8 to 14 at baseline who were participating in Project HeartBeat!, a mixed longitudinal study of cardiovascular disease (CVD) risk factor development in children. Plasma lipid concentrations were determined for each participant three times per year (every 4 months) for up to 4 years from October 1991 through August 1995. Mean total cholesterol values for individuals with epsilon2/3, epsilon3/3, and epsilon3/4 genotypes were 141.7, 161.6, and 165.9 mg/dL, respectively (P < .001). Corresponding LDL-C values for individuals with epsilon2/3, epsilon3/3, and epsilon3/4 genotypes were 74.6, 94.8, and 98.7 mg/dL, respectively (P < .001). The results of longitudinal modeling indicated that age trajectories for total cholesterol and LDL-C varied significantly by apo E genotype. Individuals with epsilon3/3 and epsilon3/4 genotypes exhibited similar patterns of change in total cholesterol and LDL-C from ages 8 to 18, while individuals with the epsilon2/3 genotype demonstrated a significantly different pattern of change (age2 x genotype interaction, P < .05). For example, individuals with the epsilon2/3 genotype showed a slight increase in total cholesterol from approximately 141 to 146 mg/dL from ages 8 to 10; total cholesterol then decreased monotonically from ages 10 to 18 from 146 to 115 mg/dL. The apo E effect on total cholesterol and LDL-C and their change during adolescence is strong and may be modified by factors affecting growth, maturation, and reproductive function.

Bioanalytical applications of polyion-sensitive electrodes

Recent developments in the design and bioanalytical applications of polyion-sensitive electrodes (PSEs) are reviewed. The general electrochemical principles governing the potentiometric response of such polymer membrane-based devices are summarized and new directions for the use of these novel sensors are detailed. These new directions include basic fundamental studies aimed at determining the thermodynamics of polyion extraction into ion exchanger-doped polymeric membranes, new methods to quantitate the anticoagulant drug heparin in whole blood via titrations with polycationic protamine, selective assays of protease activities (and inhibitors of such activities) using natural and synthetic polyionic peptides as substrates, and novel homogeneous immunoassay schemes based on potentiometric polyion detection.

The role of subunit composition on prepulse facilitation of the cardiac L-type calcium channel

Facilitation of calcium current by depolarizing prepulses has been observed in many cells including cardiac muscle. The mechanism underlying prepulse facilitation is controversial with respect to the requirements of channel subunits and cAMP kinase. We found that coexpression of the cardiac alpha1C-a subunit with the cardiac beta2a subunit significantly promotes the facilitation of I(Ba) by strong depolarizing prepulses. The magnitude of I(Ba) facilitation depended on the voltage potential of the prepulse and the interval duration between prepulse and test pulse. Prepulse facilitation was not affected by coexpression of AKAP79 and conditions favoring cAMP-dependent phosphorylation. Prepulse facilitation was also observed in cells expressing an alpha1C-a subunit which was truncated at residue 1733 removing the cAMP kinase site at Ser-1928. Facilitation was abolished by coexpression of the alpha2delta-1 or alpha2delta-3 subunit. We conclude that the expressed alpha1C-a beta2a complex is sufficient to support prepulse facilitation. Facilitation is prevented by coexpression of the alpha2delta subunit.

Sidechain and backbone requirements for anti-invasive activity of laminin peptide 11

The structure of laminin peptide 11 (CDPGYIGSR-NH2) contains valuable information for the design of mimetic compounds with anti-invasive and anti-metastatic properties. An alanine scan replacement experiment identified Tyr5, Ile6 and Arg9 residues as contributing significantly to anti-invasive activity. Circular dichroism spectra and NMR alphaH chemical shift values both supported the existence of populations of nonrandom coil solution structures for the analogs tested. A D-Ala4 for Gly4 substituted analog completely lost activity, while an L-Ala4 for Gly4 substituted analog retained half the activity of the parent peptide. These results complement our previous findings with D/L alanine substitutions at the Gly7 position, and together they suggest an 'S'-shaped backbone as likely for the active peptide conformation. NMR-constrained molecular modeling supported a direct involvement of the Tyr5 and Ile6 sidechains in conferring bioactivity, and indicated that the Tyr5 sidechain was buried in the Ala2 for Asp2 substitution. Based on the fact that the peptide 11 sequence derives from the disulfide bonded c-loop of an LE-repeat, we synthesized the cyclic CDPGYIGSRC-NH2 peptide. This analog exhibited good anti-invasive and anti-metastatic activity. NMR modeling experiments suggested that the trans-proline cyclic peptide, would favor an 'S'-shaped backbone conformation. Full retro-inverso analogs of peptide 11 were shown to have anti-invasive activity inferior to that of peptide 11. This weak bioactivity was probed using NMR-constrained molecular dynamics, and revealed potential conformations which limited the ability of the required sidechains to mimic the positions of those in the native peptide conformations.

[The effect of estrogen replacement therapy on plasma nitric oxide levels in postmenopausal women]

OBJECTIVE

To investigate the effect of estrogen replacement therapy (ERT) on plasma nitric oxide (NO) levels in postmenopausal women (PMW).

METHODS

The plasma concentrations of NO and serum concentrations of estradiol (E2) were assessed before and 4 weeks after placebo or ERT administration in 10 cases of healthy PMW (control group), 17 cases of healthy PMW (healthy group) and 21 cases of PMW with hyperlipidemia (hyperlipidemia group) respectively.

RESULTS

There was no difference in NO concentrations between before and after placebo administration in control group. In healthy and hyperlipidemia groups, the mean concentrations of NO were significantly higher 4 weeks after ERT administration than baseline. The positive correlation between the mean percent increase of NO and the E2 concentrations after ERT administration was statistically significant in healthy group.

CONCLUSION

The increase of plasma NO concentrations caused by ERT may contribute to it cardiovascular protective effect in PMW.

[Saccharification of corn stover by immobilized Trichoderma reesei cells]

The mycelia of Trichoderma reesei Rut C30 were adsorbed and immobilized within the porous polyurethane supporter. It was found that the synthesis of cellulase by the immobilized cells and the enzymatic hydrolysis of corn stover were able to be carried out in a nitrogen source-limiting medium. Under repeated batch processes with 60 g/L corn stover pretreated by 2% NaOH at 85 degrees C, the average cellulase activity (FPA) was 0.70 IU/ml, the concentration and yield of the reducing sugar were 26.41 g/L and 89.11% respectively after shaking culture at 150 r/min, 30 degrees C, pH 4.8 for 108 h. Total of 12 repeated batches were performed in 54 days. The immobilized cells kept the weight around 10 g/L. The fed-batch process was also studied with the same immobilized cells. Total of 120 g/L corn stover was added in different feeding manners. The reducing sugar of 52.8 g/L was produced after 7 days and the saccharification efficiency (89.2%) was almost the same as the batch process. The results indicated that the cellulase production and cellulosic material saccharification in situs by the immobilized Trichoderma reesei cells is an convenient and effective process for conversion and utilization of renewable biomass.

Finding health and AIDS information in the mass media: an exploratory study among Chinese college students

Western health officials believe the incidence of HIV infection in the People's Republic of China is much higher than has been reported, but knowledge about the disease remains low. This paper describes a preliminary study of Chinese college students' AIDS knowledge and beliefs and of the acceptability of mass media for AIDS education. Focus group interviews of 73 Xiamen University students showed that the students used radio more consistently than any other media and viewed magazines as the best media source of health information. However, they expressed a general distrust of the health information media offer. They possessed quite a bit of accurate information about AIDS but also harbored many inaccurate beliefs. Most felt that their personal risk from AIDS was very low because they felt distanced--either geographically or morally--from those at risk. Disturbing numbers felt that fate, not individual behavior, determines whether or not a person contracts HIV. The paper discusses the study's implications for future research.

[The expression of P16, Rb and cyclin D1 and biological behavior of laryngeal cancer]

To determine the effect of gene of carcinorma on the proliferation and regulation in primary laryngeal cancer, P16, Rb, Cyclin D1 were examined with immunohistochemical SABC method in 36 cases of primary laryngeal cancer. The results showed: P16 was positive in 11 of 36 in carcinoma specimens (30.6%), 22 of 36 in the specimens surrounding the carcinoma (61.1%) were positive. The difference was significant (P < 0.05). The positive rates of Rb and Cyclin D1 were 61.1% and 47.2% respectively. Comparing the positive rate of P16 to Rb was more significantly (P < 0.05). In most circumstances, when Rb was positive, P16 was negative and vice versa. The positive rate of Rb correlated with the one of Cyclin D1 positively by rank correlation. The expression of P16 and Rb was significantly different between well and poor tissues differenciation. The expression had no significant difference in the same antibody in various clinical stage and position or in the same stage and position but different antibody. The results suggest that the feedback regulation chain consisted of P16 plays an important role in the proliferation and regulation.

RF2a, a bZIP transcriptional activator of the phloem-specific rice tungro bacilliform virus promoter, functions in vascular development

Rice tungro bacilliform virus (RTBV) replicates only in phloem cells in infected rice plants and its promoter drives strong phloem-specific reporter gene expression in transgenic rice plants. We isolated a cDNA encoding a basic leucine zipper (bZIP) protein, RF2a, which binds to the Box II cis element that is important for expression from the promoter. RF2a, which stimulates Box II-dependent transcription in a homologous in vitro transcription system, accumulates in nuclei of phloem and certain other cell types in shoots, but is found at only very low levels in roots. Transgenic antisense plants in which RF2a accumulation was suppressed had normal roots but stunted, twisted leaves with small, disorganized vascular bundles, an enlarged sclerenchyma and large air spaces. We propose that the RTBV promoter exploits a host transcription factor that is critical for leaf tissue differentiation and vascular development for its expression.

Effects of acidosis or alkalosis on the actions of nifedipine on excitation-contraction coupling in the rat tail artery

1. The clinical success of calcium channel blockers in the management of organ ischaemia is less than theoretically anticipated. Blood gas/pH changes are associated with organ ischaemia; therefore, we studied the possibility that pH changes could alter the pharmacological effects of the calcium channel blocker nifedipine on rat tail artery contracted by either noradrenaline (NA) or potassium. 2. Segments (2-2.5 cm) of the proximal third of the male Sprague-Dawley rat tail ventral artery were initially bathed and perfused with a physiological salt solution (PSS; pH 7.48) for 25-30 min, after which time bathing/perfusion was continued with a nominally calcium-free PSS made acidotic (pH 7.20), alkalotic (pH 7.67) or unaltered (control). After equilibration, the perfusion pressure (PP) responses to increasing concentrations of calcium in the presence of NA (3.0 mumol/L) or potassium (100 mmol/L) with nifedipine or its vehicle were recorded. 3. The calcium sensitivity of potassium- or NA-stimulated rat tail arteries was reduced during acidosis, as was the maximum PP in potassium- but not NA-stimulated tissues. Alkalosis reduced the calcium sensitivity in potassium- but not NA-stimulated contraction and had no effect on maximum PP. 4. The inhibitory effect of nifedipine (0.6 mumol/L) on contraction was enhanced during acidosis in either NA- or potassium-stimulated arteries and also during alkalosis in NA-treated arteries, although it had little effect during normal conditions. 5. The results indicate that changes in pH alter the vascular contractility profile in a manner dependent on the excitation-contraction coupling mode. The calcium antagonistic effect of nifedipine is pH dependent and it is suggested that pH changes associated with ischaemic conditions may alter the therapeutic profile of nifedipine.

Development of cardiovascular risk factors from ages 8 to 18 in Project HeartBeat! Study design and patterns of change in plasma total cholesterol concentration

BACKGROUND

Project HeartBeat! is a longitudinal study of the development of cardiovascular risk factors as growth processes. Patterns of serial change, or trajectories, from ages 8 to 18 years for plasma total cholesterol concentration (TC) and percent body fat illustrate the design and synthetic cohort approach of the study.

METHODS AND RESULTS

Six hundred seventy-eight children (49.1% female, 20.1% black) entered the study at ages 8, 11, and 14 years and were followed up with examinations every 4 months for < or = 4 years. Multilevel analysis demonstrated trajectories for population mean values of TC and percent body fat in sex-specific synthetic cohorts from ages 8 to 18 years. Polyphasic patterns of change in TC were confirmed, with notable sex differences in age patterns and with minimum mean values of TC of 3.85 mmol/L for females and 3.59 for males. As illustrated by data for males, the approximate 75th percentile values of mean TC ranged from 4.78 mmol/L at its early peak to 4.06 at its late-teen nadir. Percent body fat exhibited a trajectory closely parallel with that for TC only for males and appeared to be unrelated for females.

CONCLUSIONS

The polyphasic trajectory for TC from ages 8 to 18 years differs between females and males, indicates marked age variation in 75th percentile values and, in males only, closely parallels the trajectory for percent body fat. These and other results indicate the value of both follow-up every 4 months across age intervals to detect rapid risk factor change and the synthetic cohort approach for gaining new insights into the dynamics and possible determinants of this change from ages 8 to 18 years.

Experimental study on biodynamic response to vibration in human and animals

In order to study the characteristics of human dynamic response to vibration, 56 subjects were exposed to vibration on X, Y and Z axes. It showed that there were two resonance peaks of most local parts of the human body. The curves of transmissibility are essentially the same in all the subjects. It was found that resonance frequencies of the human body decreased with increase of G levels of vibration. These characteristics were also proved in animals. Using three-level artificial neural network, common reflective relation of the resonance frequency with height and weight of the human body and exciting acceleration were obtained. The above findings might be applicable to studies of vibration ergonomics.

Identification and functional characterization of a calcium channel gamma subunit

A positive selection technique was used to identify novel auxiliary calcium channel subunits that are similar to the skeletal muscle gamma subunit. A new rat gamma subunit cDNA was found, which was highly expressed in skeletal muscle tissue and was detected by RT-PCR in cardiac tissue. The 223-amino-acid-protein shares 84% and 79% identity, respectively, with the human and rabbit skeletal muscle subunits. Northern blot analysis revealed a single transcript of 1.5 kb in rat skeletal muscle, but not in cardiac tissue. Transient coexpression with the cardiac calcium channel complex demonstrated that the gamma subunit shifted the inactivation curve to negative potentials and accelerated current inactivation without changing other voltage-dependent properties of the channel.

[Development of a SIRI-TOFMS and the application research progress]

The only one set of Sputter Initiated Resonance Ionization-Time of Flight Mass Spectrometer (SIRI-TOFMS) in China was designed and developed. A liquid gallium ion source with micron level diameter of beam, frame-style piezoeletric ceramic sub-micron sample manipulator, a secondary electron imaging system and a computer controlled precise targeting system as well as a real colour big screen image displaying system were added so as to improve its microanalysis capability. By means of this apparatus, trace analysis of Au in minerals and Cu in standard steel samples were carried out. The detection limit of them is 40ng/ and microg/g level, respectively. Aside from the above detections, other preliminary researches ere also performed.

Inhibition of plasma membrane NADH oxidase activity and growth of HeLa cells by natural and synthetic retinoids

Several retinoids, both natural and synthetic, were evaluated for their ability to modulate NADH oxidase activity of plasma membranes of cultured HeLa cells and the growth of HeLa cells in culture. Both NADH oxidase activity and the growth of cells were inhibited by the naturally-occurring retinoids all trans-retinoic acid (tretinoin) and retinol as well as by the synthetic retinoids, trans-acitretin, 13-cis-acitretin, etretinate and arotonoid ethylester (Ro 13-6298). For all retinoids tested, inhibition of NADH oxidase activity and inhibition of growth were correlated closely. With tretinoin, etretinate and arotonoid ethylester, NADH oxidase activity and cell growth were inhibited in parallel in proportion to the logarithm of retinoid concentration over the range of concentrations 10(-8) to 10(-5) M. Approximately 70% inhibition of both NADH oxidase activity and growth was reached at 10 microM. With retinol, trans-acitretin and 13-cis-acitretin, inhibition of NADH oxidase activity and growth also were correlated but maximum inhibition of both was about 40% at 10 microM. The possibility is suggested that inhibition of the plasma membrane NADH oxidase activity by retinoids may be related to their mechanism of inhibition of growth of HeLa cells in culture.

An automated nursing assessment for a teaching hospital

An automated nursing assessment has been developed by the Department of Nursing and the Center for Clinical Computing at Beth Israel Hospital and Harvard Medical School. Designed to collect standardized data using structured and free-text entry of patient-specific data, the program has been in use on all medical and surgical inpatient units since July 1994. Before it was implemented, each nursing unit had used its own format to document the nursing assessment and there was no standardization of information. The automated system has decreased repetitive entry of data items, improved the legibility and availability of baseline information, increased patient-related communication between nursing units, and reduced the average time spent documenting the admission assessment from 60 to 30 minutes.

Crystal structure of Arabidopsis thaliana NADPH dependent thioredoxin reductase at 2.5 A resolution

Thioredoxin exists in all organisms and is responsible for the hydrogen transfer to important enzymes for ribonucleotide reduction and the reduction of methionine sulphoxide and sulphate. Thioredoxins have also been shown to regulate enzyme activity in plants and are also involved in the regulation of transcription factors and several other regulatory activities. Thioredoxin is reduced by the flavoenzyme thioredoxin reductase using NADPH. We have now determined the first structure of a eukaryotic thioredoxin reductase, from the plant Arabidopsis thaliana, at 2.5 A resolution. The dimeric A. thaliana thioredoxin reductase is structurally similar to that of the Escherichia coli enzyme, and most differences occur in the loops. Because the plant and E. coli enzymes have the same architecture, with the same dimeric structure and the same position of the redox active disulphide bond, a similar mechanism that involves very large domain rotations is likely for the two enzymes. The subunit is divided into two domains, one that binds FAD and one that binds NADPH. The relative positions of the domains in A. thaliana thioredoxin reductase differ from those of the E. coli reductase. When the FAD domains are superimposed, the NADPH domain of A. thaliana thioredoxin reductase must be rotated by 8 degrees to superimpose on the corresponding domain of the E. coli enzyme. The domain rotation we now observe is much smaller than necessary for the thioredoxin reduction cycle.

[Lectin-binding histochemical study on developing corneal epithelium and stroma of normal human being]

PURPOSE

To study glycoconjugates in developing cornea of normal human.

METHODS

Lectin-binding histochemical method with five biotin-coupled lectins (conA, LCA, PNA, WGA, RCA).

RESULTS

1. WGA mainly stained the membrane of epithelial cells, especially in surface cells. It also stained anterior stroma of embryo. 2. All the layers of epithelium could be stained by conA, uneven stain was seen in stroma of embryo corneas. 3. RCA, LCA receptor distributed in base of cornea epithelium. 4. PNA can only stain cornea epithelium of 16 embryo.

CONCLUSIONS

1. Glycoconjugates of binding conA, WGA, PNA, LCA, RCA are in the developing corneas of human. 2. The distribution of these lectin receptors may change with corneal developing. It may be related to the maturity of corneas.

Effects of low and high dose administration of bis(maltolato)oxovanadium(IV) on fa/fa Zucker rats

The fatty Zucker rat, characterized by obesity, hyperinsulinemia, hyperlipidemia, and mild hyperglycemia, has been suggested as an animal model of non-insulin-dependent diabetes mellitus. The present study examined the chronic dose-dependent effect of bis(maltolato)oxovanadium(IV), a potent insulin mimetic, in this animal model of diabetes. Chronic (6 weeks) oral administration of bis(maltolato)oxovanadium(IV) (0.06 mmol.kg-1.day-1, low dose study) was effective in reducing the hyperinsulinemia associated with the fatty Zucker rat model (termination insulin: lean, 82.8 +/- 21.6; fatty, 732 +/- 89.4; fatty treated, 336 +/- 126.6 pmol/L; p < 0.05). Pancreatic perfusion data indicated a significant improvement in insulin secretory function in the fatty rats. The dose dependency of this relationship was observed in the high dose study (0.128 mmol.kg-1.day-1 for 14 weeks), wherein bis(maltolato)oxovanadium(IV) treatment restored plasma insulin levels in the fatty rats to lean levels (termination insulin: lean, 199.2 +/- 17.4; fatty 660.6 +/- 12.6; fatty treated, 153.6 +/- 9.6 pmol/L; p < 0.05) and significantly improved insulin response to a glucose challenge. In addition, bis(maltolato)oxovanadium(IV) treatment (high dose study) ameliorated the age-dependent increase in blood pressure observed in fatty Zucker rats (systolic blood pressure: lean, 127 +/- 10; fatty, 176 +/- 5; fatty treated, 156 +/- 9 mmHg (1 mmHg = 133.3 Pa)). These data indicate that chronic oral administration of bis(maltolato)oxovanadium(IV) in the drinking water was effective in reducing hyperinsulinemia, insulin resistance, glucose intolerance, and hypertension in the fatty Zucker rat.

[Distribution of Bacillus thuringiensis in soils of north and south of China]

221 isolates of Bacillus thuringiensis were isolated in 1491 soil samples from North and South of China. H-serotypes and larvicidal characters of all Bt isolates have been identified. The rate of Bt-harbouring soil sample and the rate of Bt isolates in Northeast and Neimeng were in 12.6% and 17.2% respectively. Predominant serotypes were H4, H10, H3, H13, H5 and H29. The most fertile Bt-harbouring area was the Heilongjiang Province with rate of Bt-harbouring sample of 21.4% and rate of Bt isolate of 29.4%. Rate of Bt-harbouring sample and rate of Bt isolate in Northwest area were 6.6% and 7.1% respectively. Main serotypes were H4, H5, H19, H10 and H3. In four provinces of Southern China, both rates above were 18.6% and 29.5%, but frequency of Bt distribution was varied seriously in different distinct. Predominant serotypes in soils from Southern China were H3 and H5. Results of bioassay showed that the percentage of strains high active to Heliothis armigera and Plogioidera versicolora were 1.6% and 1.1% in soils from North of China. In contrast to North of China, Bt strains active to H. armigera were 5.3% and none of Bt was effective to P. versicolora in South of China. A strain H27-05 was high toxic to H. armigera and showed temperate toxicity to P. versicolora.

Influence of pH changes on the actions of verapamil on vascular excitation-contraction coupling

We have previously shown that pH changes alter the cardiovascular responses to verapamil in rat, in vivo and in isolated rat heart. The current study investigated the influence of pH changes on the actions of verapamil on potassium- or noradrenaline-stimulated contraction in rat tail arteries. The proximal 2-2.5 cm of ventral tail artery was bathed in and perfused initially (20-25 min) with physiological salt solution (pH 7.4) which was later made calcium-free at pH 7.4 (control), pH 7.2 (acidosis) or pH 7.67 (alkalosis). After equilibration each artery was exposed to verapamil following which the contractile responses to increasing concentrations of calcium were recorded. The patterns of responses in noradrenaline- or potassium-stimulated arteries were different. In normal conditions, the vasodilator effect of verapamil was predominant in potassium-stimulated arteries but less in the noradrenaline-stimulated preparations. With pH changes the effect of verapamil was enhanced more in noradrenaline- than in potassium-stimulated arteries. It is postulated that pathology-induced changes in the character of calcium channels could alter the effect of calcium channel blockers.

Cardiac cytotoxic mechanism mediated by antibodies against myocardial mitochondrial ADP/ATP carrier in patients with dilated cardiomyopathy

OBJECTIVE

To investigate mechanism of the antibody-mediated cardiac cytotoxicity and clinical significance in dilated cardiomyopathy (DCM), and study the effects of the antibodies against the myocardial mitochondrial ADP / ATP carrier from sera of patients with dilated cardiomyopathy on the guinea pig ventricular myocytes.

PATIENTS AND METHODS

This study included 18 patients with DCM (12 men and 6 women), with mean age of 43 years. Control group included 18 health donors, (9 men and 9 women), with mean age of 32 years. The antibodies against the ADP / ATP carrier and cell membrane 52 000 peptide were examined by immunoblotting. The antibody-mediated cardiac cytotoxicity was studied with the cytotoxic test and whole cell patch-clamp technique.

RESULTS

The antibodies against myocardial mitochondrial ADP / ATP carrier and cell membrane 52 000 peptide were positive in 18 patients with DCM, while negative in controls. The antibodies induced cytotoxic damage with time-dependent and enhanced Ca-current in cardiac myocytes. The increasing amplitude of peak Ca(2+)-current was 100 pA-840 pA (n = 8) in different dilution of the antibodies. The effect of the antibodies might be inhibited by verapamil, and were null in controls (n = 4).

CONCLUSIONS

The above findings suggest that an increase in the antibody-mediated Ca(2+)-current of cardiac myocytes is related to the cytotoxic damage in dilated cardiomyopathy.

AIDS knowledge, attitudes and beliefs among Chinese college students: implications for PSA development

With growing numbers of reported HIV cases in The People's Republic of China, PRC health officials face the same information dissemination problems that have plagued other nations for a decade. The purpose of this study was to begin to understand Chinese college students' knowledge, attitudes and beliefs about HIV/AIDS as well as the cultural barriers which may prevent the acceptance of AIDS public service efforts. Focus group interviews were conducted with 76 college students at Xiamen University, PRC. Interviews revealed that many inaccurate beliefs exist regarding the AIDS disease and its modes of transmission. While many of the respondents reported that fate was the determining factor in trans mission of HIV, most felt distanced--physically, morally and culturally--from those at risk.

Increased potency of vanadium using organic ligands

The in vivo glucose lowering effect of orally administered inorganic vanadium compounds in diabetes was first reported in our laboratory in 1985. While both vanadate and vanadyl forms of vanadium are orally active, they are still not well absorbed. We have synthesized several organic vanadium compounds and one compound, bis(maltolato)oxovanadium(lV) or BMOV, has been extensively investigated. BMOV proved effective in lowering plasma glucose and lipids in STZ-diabetic rats when administered in drinking water over a 25 week period. The maintenance dose (0.18 mmol/kg/day) was approximately 50% of that required for vanadyl sulfate (VS). Secondary complications of diabetes were prevented by BMOV and no marked toxicity was noted. Oral gavage of STZ-diabetic rats with BMOV also reduced blood glucose levels. The ED50 for BMOV was 0.5 mmol/kg, while for VS the estimated ED50 was 0.9 mmol/kg. BMOV was also effective by the intraperitoneal route in STZ-diabetic rats. The ED50 was 0.08 mmol/kg compared to 0.22 mmol/kg for VS. Some animals treated p.o. or i.p. remained euglycemic for up to 14 weeks. An i.v. infusion of BMOV of 0.05 mmol/kg over a 30 min period reduced plasma glucose levels by 50% while VS was not effective.

[Predictive value of urinary calcium measurement on occurrence of pregnancy-induced hypertension]

OBJECTIVE

To study the predictive value of urinary calcium excretion on occurrence of pregnancy-induced hypertension (PIH).

METHODS

Twenty-four-hour urinary calcium excretion, urinary calcium concentration and urinary calcium/creatinine (Ca/Cr) ratio were determined in 184 normal pregnant women and 30 patients with PIH.

RESULTS

Twenty-four-hour urinary calcium excretion, urinary calcium concentration, and Ca/Cr ratio in PIH group were significantly lower than that in normal pregnant group (P < 0.01). 3 mmol/L of urinary calcium concentration and 0.04 of Ca/Cr ratio were chosen as predictive thresholds for development of PIH, with sensitivity of 76.2%, 81.0% and specificity of 97.5%, 98.2% respectively.

CONCLUSIONS

Low urinary calcium excretion is a valuable marker for prediction of PIH.

Laser Raman spectrometry study on experimental galactose-induced cataract

PURPOSE

To observe the dynamic changes of hydration in galactose induced cataract.

METHODS

Two groups of Wistar rats were used in the experiment. There were 12 rats in the experimental group, which were fed diet of 50% D-Galactose standard feed; while the control group had 8 rats fed standard feed. Their other living conditions were the same. At desired time periods, two Wistar rats fed galactose and one normal control were selected and killed 20 minutes before the instrument examination respectively, then, their lenses were removed from the orbs by a posterior approach. The cleaned fresh lens was placed in a quartz cuvette with Tris buffered balanced salt solution containing 5.5 mmol/L glucose. The quartz cuvette was placed on the stage of the Spectrometer. The laser beam was focused at the lens nuclear from the bottom of the cuvette and the scattered light was collected at 90 degrees to the incident beam.

RESULTS

Raman spectroscopy showed that (1) during the formation of galactose cataract, the water signal (at 3390cm-1) increased obviously, and the ratio of I3390/I2935 increased from 0.31 (3 days) to 2.26 (17 days), which is correlated with the imbibition of water in the lens nuclear; (2) the hydration of lens nuclear could be divided into two phases. The ratio I3390/I2935 was increased slowly and steadily by 11 days after galactose feeding. Then, the ratio turned to increase quite fast till 17 days.

CONCLUSION

The hydration of nuclear is changed simultaneously with the formation of cataract. The hydration of nuclear is mainly due to the imbalance of Na+/K+.

Lack of haematological effect of oral vanadium treatment in rats

Haematological effects of oral administration of ammonium metavanadate 0.19 mmol V/kg/day, vanadyl sulphate 0.15 mmol V/kg/day, and bis(maltolato)oxovanadium (i.v.) 0.18 mmol V/kg/day in drinking water for 12 weeks were investigated in Wistar rats. Some selected haematological indices of the peripheral blood, including haematocrit, haemoglobin, erythrocyte count, reticulocyte percentage, leukocyte count and its differential count, platelet count, and osmotic fragility of the erythrocyte were determined using the standard methods. It was found that, throughout the 12-week experimental period, there were no significant differences between the untreated controls and various groups of vanadium-treated rats in all of the parameters measured. It is thus concluded that ammonium metavanadate, vanadyl sulphate, and bis(maltolato) oxovanadium (i.v.), at least at the doses and at the duration of treatment employed, do not produce significant haematological toxicity in rats.

Fructose-induced hypertension in rats is concentration- and duration-dependent

The present study determined the most suitable concentration and duration of fructose treatment for inducing hypertension in Wistar rats. The correlation between fructose-induced hypertension and hyperinsulinemia was also evaluated. The rats were treated with 5%, 10%, or 20% fructose in drinking water. The greatest changes, including increases in blood pressure, fluid intake, and plasma levels of insulin, glucose, and triglycerides, and a decrease in food intake following fructose treatment, were observed with the 10% solution. The times of the onset and maximum response differed for the various parameters measured. The increase in blood pressure occurred earlier than the increase in the plasma insulin level. All abnormalities disappeared rapidly after fructose withdrawal. There was no significant correlation between plasma insulin level and systolic blood pressure. In conclusion, treatment with 10% fructose in drinking water (equivalent to a diet containing 48-57% fructose) for one week or longer is appropriate for the rapid production of fructose-induced hypertension in Wistar rats, which is associated with elevated levels of plasma insulin, glucose, and triglycerides.

[Inhibition of glutamate uptake in rat brain synaptosome by pyrethroids]

In vitro studies showed deltamethrin (1 x 10(-7)-1 x 10(-4) mol/L) could inhibit 3H-DL-glutamate uptake in rat cerebral cortex and hippocampus synaptosome by 7.2%-21.5% and 10.4%-25.1%, respectively, with a dose-response pattern. But only in high-dose permethrin (1 x 10(-4) mol/L) can significantly reduce 3H-DL-glutamate uptake in rat hippocampus synaptosome. In addition, deltamethrin also can reduce 3H-DL-glutamate uptake in cerebellum and striatum of rats by 16.5% and 31.8%, respectively. It is suggested that both deltamethrin and permethrin, especially the former, can disturb the function of brain tissue in high-affinity-glutamate uptake with their alpha-cyano-group. So pyrethroids could play an important role in cerebral stimulation in mammals.

Ascorbic acid supplementation prevents hyperlipidemia and improves myocardial performance in streptozotocin-diabetic rats

The present study investigated the effects of ascorbic acid (AA) supplementation on the cardiac performance and the plasma levels of glucose, insulin, triglycerides, cholesterol and free fatty acid in diabetic and non-diabetic rats. Diabetes was induced by intravenous injection of streptozotocin (STZ) 55 mg/kg. AA was given in drinking water in concentrations of 1 g/l or 2 g/l for 8 weeks after STZ injection. Myocardial performance was determined using the isolated perfused working heart preparations. Following AA supplementation, there were no significant changes in any of the parameters measured in non-diabetic rats; however, the occurrence of polydipsia, hyperphagia, hyperlipidemia and myocardial dysfunction in STZ-diabetic rats was significantly alleviated in a dose-dependent manner. Nevertheless, the decreased body weight gain, hypoinsulinemia and hyperglycemia in diabetic animals were not affected. The data show that AA supplementation in STZ-diabetic rats improves both hyperlipidemia and cardiac function. However, the mechanisms of these effects and the correlation between these improvements are not clear.

Improvement in cardiac function in streptozotocin-diabetic rats by salt loading

Effects of salt loading by drinking 0.9% NaCl solution on the myocardial performance in nondiabetic and diabetic Wistar rats were studied using the isolated working heart apparatus. Body weight and fluid and food intakes of these animals were monitored. Blood pressure and plasma levels of glucose, insulin, cholesterol, and triglycerides were also measured. Diabetes was induced by intravenous injection of streptozotocin (60 mg/kg). Diabetic rats were found to develop myocardial dysfunction at 8 weeks after STZ injection, accompanied by significant increases in food and fluid intakes, slowed body weight gain, hyperglycemia, hypoinsulinemia, and hyperlipidemia but without significant changes in blood pressure. Salt loading did not cause significant changes in any of the parameters studied in nondiabetic rats. However, in streptozotocin-diabetic rats given saline to drink, the impaired myocardial function was significantly improved and was associated with a significant reduction in hyperphagia and hyperlipidemia. Plasma glucose levels significantly decreased at weeks 1-3 but increased to the levels of untreated diabetic animals at weeks 4-7. There was an increase in fluid intake, but neither blood pressure nor plasma insulin levels were significantly affected. It is suggested that the improvements in cardiac function and hyperlipidemia in diabetic rats by salt loading may be related to each other; however, the mechanisms for these effects are not clear but are unlikely to be due to changes in glycemic control.

Toxicity studies on one-year treatment of non-diabetic and streptozotocin-diabetic rats with vanadyl sulphate

Streptozotocin-diabetic and non-diabetic rats were given vanadyl sulphate in drinking water at concentrations of 0.5-1.5 mg/ml for one year. It was found that vanadyl treatment did not produce persistent changes in plasma aspartate aminotransferase, alanine aminotransferase, and urea, specific morphological abnormalities in the brain, thymus, heart, lung, liver, spleen, pancreas, kidney, adrenal, or testis, or abnormal organ weight/body weight ratio for these organs in either non-diabetic or diabetic animals. Treatment significantly reduced the incidence of the occurrence of urinary stones in non-diabetic rats. In diabetic animals vanadyl treatment significantly reduced the mortality rate and prevented the elevation of plasma levels of alanine aminotransferase and urea, the increases in organ size, and the occurrence of megacolon but did not affect the development of renal and testicular tumours. Plasma and tissue concentrations of vanadium were determined and found to have the following order of distribution: bone > kidney > testis > liver > pancreas > plasma > brain. Vanadium was retained in these organs at 16 weeks following vanadyl withdrawal while the plasma levels were beneath detection limits. It is concluded that vanadyl sulphate at antidiabetic doses is not significantly toxic to rats following a one-year administration in drinking water, but vanadium may be retained in various organs for months after cessation of treatment.