Evaluation of plant availability of soil trace metals by chemical fractionation and multiple regression analysis

Soil samples with a range of chemical and physical properties were collected from 10 different rural regions of China. Trace metals (Ni, Co, Cu, and Pb) in the soils were partitioned by a sequential extraction procedure into Mg(NO(3))(2) extractable (F1), CH(3)COONa extractable (F2), NH(2)OH.HCl extractable (F3), HNO(3)?H(2)O(2) extractable (F4), and residual (F5) fractions. Chemical fractionation showed that F1 fraction of the metals was less than 1% and residue was the dominant form for Cu and Ni in all samples, and for Co in most of the samples. Significant interrelationships of the fractions varied considerably with the different metals. Winter wheat (Triticum aestivum L.) and alfalfa (Medicago sativa L.) had been grown on the soils in a pot-culture experiment under greenhouse conditions for 40 days. Metal availability to the plants was evaluated by simple and multiple regression analysis. The Mg(NO(3))(2) extractable Co (F1) was significantly correlated with Co concentrations in different parts of wheat and in the whole of alfalfa. For the other metals, the independent variables of the multiple regression models, chosen by stepwise selection, were given as: F1 and F2 + F3 + F4 for Ni; F1, F2 + F3 and F4 for Cu; and F3 + F4 for Pb. The results of this study demonstrate that the sequential extraction procedure, in conjunction with multiple regression models using a combination of correlated fractions as an independent variable, may be useful for the prediction of plant absorption of trace metals in soils.

The effect of acupuncture on spinal motor neuron excitability in stroke patients

BACKGROUND

Spasticity is a common symptom in stroke patients, and its management constitutes a major problem in their rehabilitation. Acupuncture has been applied with moderate effect; their has been clinical experience but little objective evidence to support its use. H-reflex recovery time and H recovery curve were quantitative methods applied to measure spinal motor neuron excitability. Acupuncture for stroke patients as treatment to spastic hemiparesis was studied to see the acupuncture effect on increased spinal motor neuron excitability in spasticity.

METHODS

Sixteen stroke patients with spastic hemiparesis were collected to evaluate the therapeutic effect of acupuncture on their spinal motor neuron excitability. H-reflex recovery time and H recovery curve were applied as quantitative evaluations of spinal motor neuron excitability. Eleven age-matched normal volunteers were used as a control group.

RESULTS

The mean H-reflex recovery time of normal controls was 73.3 +/- 18.3 mesc; that of the sound-side limbs of stroke patients was 67.1 +/- 21.5msec. The difference was not significant statistically (p = 0.2). However, the mean H-reflex recovery time of the paretic limbs of stroke patients was 52.3 +/- 16.8 msec, significantly shorter than for the normal controls (p = 0.003). The mean H-reflex recovery time of the paretic limbs of stroke patients became 57.6 +/- 19.9 msec after acupuncture, significantly prolonged as compared with that before acupuncture (p = 0.03). The H recovery curve of the paretic limbs after acupuncture also approximated that of the normal controls.

CONCLUSIONS

This result provides positive evidence of increased spinal motor neuron excitability in paretic limbs of stroke patients and also of the acupuncture effect which decreased that excitability. The study also presents a simple and practical technique for measuring the effects of various types of treatments, including acupuncture, on other types of central nervous system disorders.

The neuropathology of intracerebroventricular t-butylhydroperoxide

t-Butylhydroperoxide can be used as a model oxidative stress-inducing agent in the brain following intracerebroventricular administration. Mice were treated with saline, t-butanol, or t-butylhydroperoxide. t-Butanol is the major metabolite of t-butylhydroperoxide. t-Butylhydroperoxide had a number of effects, including that it damages dopaminergic, cholinergic, and GABAergic neurons as demonstrated immunohistochemically. Electron microscopic examination demonstrated that astrocytes, oligodendrocytes, endothelial cells, pericytes, and neurons are damaged by t-butylhydroperoxide. Dopamine and its metabolites were affected in a number of brain regions, as were serotonin and its metabolite. Choline acetyl transferase activity was decreased in the striatum. Edema was apparent as assessed by tissue protein levels. There was evidence of lipid peroxidation produced by t-butylhydroperoxide in the midbrain. t-Butylhydroperoxide is a neurotoxin that may be useful in understanding the unexpected ways the brain responds to oxidative stress.

Baculovirus expression of the ADRV gene 5 encoded protein produces an oligomerized, antigenic, and immunogenic VP6 protein

Adult diarrheal rotavirus (ADRV) is a currently noncultivatable group B human rotavirus responsible for epidemic outbreaks of gastroenteritis in China. Gene segment 5 of ADRV encodes the major inner capsid protein, VP6. ADRV gene 5 was inserted into a recombinant baculovirus by homologous recombination between baculovirus shuttle plasmid pACYM1-AD5 and AcNPV genomic DNA. Baculovirus recombinants were selected visually and plaque purified and VP6 expression was detected by Coomassie staining of PAGE-separated proteins. The baculovirus-expressed gene 5 polypeptide is 44 kDa, the same as for the major inner capsid protein present on EDTA-treated ADRV virions and in vitro-expressed VP6 protein. The expressed protein is oligomeric and in the absence of reducing agents multimerizes to apparent trimer, hexamer, and greater molecular mass as assayed by SDS-PAGE. The VP6 protein is immunoprecipitable by hyperimmune serum to ADRV, human ADRV convalescent serum, by a group B-specific monoclonal antibody and by porcine group B rotavirus infection serum. The baculovirus-expressed protein is immunogenic and antibodies to the expressed protein recognize ADRV virions. The ADRV VP6 protein should be useful for developing diagnostic assays for serum antibodies to group B rotavirus as well as for generating hyperimmune serum and monoclonal antibodies for detecting viral antigen from ADRV and other group B rotaviruses.

Study on the nanosecond transient absorption spectra of hypocrellin A

In this paper, the nanosecond transient absorption spectra and the fluorescence spectra of Hypocrellin A(HA) are examined in solvents of varying polarity. There are three absorption bands in dilute HA solutions: Ia, IIa are defined as the triplet-triplet absorption of HA, the band IIIa is supposed to be the absorption of the solvent-separated ion pair (SSIP). In more concentrated solutions, only the absorption of SSIP was observed. The effects of solvent polarity on transient absorption spectra and fluorescence spectra of HA and the effect of oxygen on the intensities of the fluorescence of HA are discussed. Then a reasonable mechanism for the photolysis of HA is proposed.

Epidemiology of Helicobacter pylori in southern China: identification of early childhood as the critical period for acquisition

A large cross-sectional study to investigate the prevalence and possible modes of transmission of Helicobacter pylori was done in southern China. Serum samples (1727) were collected from Guangzhou city and three rural areas of Guangdong Province, and the prevalence of H. pylori infection was determined using an ELISA. Each subject completed a questionnaire. The overall prevalence of H. pylori infection was 44.2%; a significantly higher prevalence was found in Guangzhou (52.4%) than in the rural areas (38.6%). This difference was generally reflected in the group 0-5 years old, but the rate of increase in seroprevalence for H. pylori over 5 years of age was similar (1%/year). This study provides important new data on the acquisition of H. pylori, particularly in the early years of life, and shows that density of living conditions is a prime determinant in the acquisition of H. pylori.

Tyrosine hydroxylase-, neurotensin-, or cholecystokinin-containing neurons in the nucleus tractus solitarii send projection fibers to the nucleus accumbens in the rat

A double-labeling method combining the retrograde tracing of horseradish peroxidase (HRP) with the immunocytochemical technique was used in the present study. The results suggest that the neurons containing tyrosine hydroxylase (TH), neurotensin (NT) or cholecystokinin (CCK) in the nucleus tractus solitarii (NTS) of the rat send their axons to the nucleus accumbens bilaterally with ipsilateral dominance. HRP-TH, HRP-NT or HRP-CCK double-labeled cell bodies were mainly located in the medial and the commissural subnucleus of the NTS. HRP-TH double-labeled cells were the largest in number, followed by HRP-NT cells, with HRP-CCK cells present in the lowest numbers.

Metabolic differences and similarities of selenium in blood and brain of the rat following the administration of different selenium compounds

A common intermediate, i.e., selenite, was found in the serum of the rat; the maximum levels occurred 3 h after administration independent of chemical forms. This indicates that both the reduction of selenate to selenite, and oxidation of seleno-dl-methionine to selenite existed in the metabolic pathways of the rat. We found that water-soluble selenium compounds led to a similar maximum content in blood and serum, but seleno-dl-methionine had a higher affinity for the brain and, by gel filtration chromatography, for the higher mol-wt (25-100 K Da) fractions of serum protein, when compared with inorganic forms.

[Spermine inhibition of in vitro fertilizing ability of human spermatozoa and its possible mode of action]

The direct effect of spermine at various concentrations (0.25-8.0 mmol/L) on in vitro fertilizing ability of human spermatozoa was evaluated by the penetration test of zona-free hamster egg. To study the effect of spermine on capacitation, as judged by the rate of penetration, spermatozoa were incubated in BWW with various concentrations of spermine for 6 h at 37 degrees C. The hyperactivated motility of spermatozoa was markedly inhibited by spermine at a concentration of 4.0 mmol/L. The penetration rate was decreased proportionally to the dose of spermine used. Spermatozoa were incubated in BWW with 0.5 mmol/L spermine for 6 h and another 4 h after spermine was washed off with spermine-free BWW. The percentage of penetration was comparable to that of the control. Therefore, spermine-mediated inhibition of capacitation was reversible. Moreover, exogenous dbcAMP (0.5-1.0 mmol/L) or caffeine (10 mmol/L) could antagonize significantly the spermine-induced inhibition of capacitation with a correlation coefficient of 0.990. The content of spermine in fertile men spermatozoa was assayed by HPLC. Before capacitation spermine in spermatozoa was 7.05 micrograms/10(7) cells, whereas after capacitation it was no longer detectable, indicating that spermine may be an inhibitor of in vitro capacitation in human sperm. To study the effect of spermine on capacitated sperm, spermine was added to the BWW medium after sperm had been preincubated in spermine-free BWW. The persistent presence of spermine could interfere with spermatozoa attachment to, binding to and penetration into zona-free hamster eggs, which was related to the concentration (r = 0.820) used.(ABSTRACT TRUNCATED AT 250 WORDS)

Measurements for the nonlinear refractive index of a new kind of polymer material doped with chlorophyll using nanosecond laser pulses

A new kind of organic polymer doped with natural active chlorophyll is made, and self-focusing and saturable absorption are observed on it under the excited laser light at 532 nm with a pulse width of 20 ns. The nonlinear refractive indices n(2), estimated to be ~10(-7) cm(2)/W, measured by two methods were consistent with each other. By analyzing the experimental data based on the glassy polymer dye model, it can be confirmed that the nonlinearity is induced by the transition of excited on-site pi electrons.

Developmental capacity of mechanically bisected mouse morulae and blastocysts

Mouse embryos were mechanically bisected at the morula, early blastocyst or expanded blastocyst stages of development and cultured in vitro to the expanded blastocyst stage. Their capacity for postimplantation development was assessed after transfer to pseudopregnant foster mice. Embryos bisected at blastocyst stages had a higher survival rate in vitro than those bisected at the morula stage. Half-embryos had approximately half the number of cells at the blastocyst stage as control embryos, but the proportion of cells in the inner cell mass (ICM) was unaltered. The implantation rate of blastocysts derived from bisected embryos was only slightly lower than that of control embryos, but bisected embryos had a significantly reduced capacity to form fetuses. Histological analyses showed that failure to form a fetus is due to the absence of egg cylinder development, which correlates with the reduced number of cells in the ICM of bisected embryos. Postimplantation viability of half-embryos was significantly higher when blastocysts were transferred to Day-3 rather than Day-4 pseudopregnant recipients, presumably because of an increase in cell number in vivo prior to implantation.

Cancer mortality of Chinese in Canada

Cancer deaths determined from national vital statistics in Canadian ('Chinese') immigrants who were born in mainland China, Hong Kong or Taiwan were compared with those in the Canadian-born population. Standardized mortality ratios (SMR) based on 1981 census data and on 755 deaths among 81,740 Chinese males and 586 deaths among 83,965 females during 1980-1984, showed that the overall cancer mortality in Chinese males (SMR 141), and females (SMR 116), was significantly higher than in the Canadian-born. Moreover, SMR varied by cancer site and showed a pattern of risks similar to those reported for foreign-born Chinese in the USA: strikingly high SMR for nasopharynx and liver or gallbladder in males and females; high ratios for stomach, intestines or colon, rectum, and lung, but a low ratio for prostate in males; and high ratios for lung and cervix uteri but low ratios for breast and ovary in females. These findings indicate that useful studies on cancer mortality could be carried out in Canadian Chinese.

High-performance liquid chromatographic determination of alpha-keto acids in human serum and urine using 1,2-diamino-4,5-methylenedioxybenzene as a precolumn fluorescence derivatization reagent

A simple and highly sensitive high-performance liquid chromatographic (HPLC) method for the determination of alpha-keto acids in human serum and urine is described. In an acidic solution, twelve species of alpha-keto acids examined were converted by reaction with 1,2-diamino-4,5-methylenedioxy-benzene into highly fluorescent derivatives. The derivatives were separated isocratically by reversed-phase HPLC on a TSK gel ODS-80TM column and detected fluorimetrically. Eight alpha-keto acids in human serum and eleven alpha-keto acids in human urine can be determined simultaneously. The detection limits (signal-to-noise ratio = 5) are 6-44 fmol in an injection volume of 5 microliters. The intra-assay relative standard deviations for both serum and urine sample analyses are usually ca. 5%.

Birth patterns: are the Chinese in Guangzhou City different?

Diurnal birth patterns in the City of Guangzhou, China and the City of Calgary in Canada were compared. Chinese data were abstracted from the labor room log book of one large general hospital located in the Hai Zhu district of Guangzhou. Calgary birth data were abstracted from birth notification forms submitted to Calgary Health Services. Information included day of birth, time of delivery, type of delivery and parity. Calgary births are concentrated on Tuesdays to Fridays whereas in Guangzhou weekly patterns varied tremendously according to whether it was assisted or unassisted. Calgary births are below average at night and during evening shift. The time of birth in Guangzhou varied substantially with above average rates for non-assisted births noted at 0800-2400 h, and above average rates for assisted births noted at 0800-1700 h. Differences in hour of birth appeared to be related to obstetric intervention practices. Knowledge of birthing patterns are useful for effective hospital management.