[Genetical effect of different rye chromosomes on the acid phosphatase (Acph) secretion of common wheat roots under phosphorus starvation conditions]

The effects of different rye chromosomes on Acph secretion of common wheat roots under P starvation conditions were studied by using a set of Chinese Spring-Imperial (CS-IMP) alien addition lines as materials. The Acph activity measurement results showed that P starvation is an induction factor for Acph gene expression; Different chromosomes of Imperial rye in Chinese Spring background has different effects on the secretion of Acph by corresponding addition line roots. Among them, chromosome 1R had the strongest promoting effect; The IEF diagram of Acph isozymes clearly demonstrated that chromosome 1R in rye genome carries P starvation inducible Acph gene(s).

Reported in vivo splice-site mutations in the factor IX gene: severity of splicing defects and a hypothesis for predicting deleterious splice donor mutations

Small consensus sequences have been defined for RNA splicing, but questions about splicing in humans remain unanswered. Analysis of germline mutations in the factor IX gene offers a highly advantageous system for studying the mutational process in humans. In a sample of 860 families with hemophilia B, 9% of independent mutations are likely to disrupt splicing as their primary mode of action. This includes 26 splicing mutations reported herein. When combined with the factor IX splice mutations reported by others, at least 104 independent mutations have been observed, 80 of which are single base substitutions within the splice donor and splice acceptor consensus sequences. After analysis of these mutations, the following inferences emerge: (1) the susceptibility of a splice donor sequence to deleterious mutation depends on the degree of similarity with the donor consensus sequence, suggesting a simple "5-6 hypothesis" for predicting deleterious vs. neutral mutations; (2) the great majority of mutations that disrupt the splice donor or splice acceptor sequences result in at least a 100-fold decrement in factor IX coagulant activity, indicating that the mutations at these sites generally function as an on/off switch; (3) mutations that create cryptic splice junctions or that shorten but do not interrupt the polypyrimidine tract in the splice acceptor sequence can reduce splicing by a variable amount; and (4) there are thousands of potential donor-acceptor consensus sequence combinations in the 38-kb factor IX gene region apparently not reduced by evolutionary selective pressure, presenting an apparent paradox; i.e., mutations in the donor and acceptor consensus sequences at intron/exon splice junctions can dramatically alter normal splicing, yet, appropriately spaced, good matches to the consensus sequences do not predispose to significant amounts of alternative splicing.

Evidence of inability to fully activate human limb muscle

The purpose of this study was to determine whether muscle activation level estimated by twitch interpolation technique was different when an electrical stimulus was applied during a dynamic force (DF; force rising) task from that when the stimulus was applied during a static force (SF; constant force) task. Fourteen subjects performed voluntary SF and DF contractions involving isometric elbow flexion at seven voluntary force levels. At each level, the electrical stimulation was applied to the surface of the biceps brachii muscle when the force was steady (SF task) and when the force was rising (DF task). The voluntary activation level of the biceps brachii muscle during the SF maximal voluntary contraction (MVC) was 98.5% and that during the DF MVC task was significantly lower (94.5%; P < 0.05). The motoneurons and/or muscle fibers may become more excitable during the DF task so that the same stimulus can recruit those that are otherwise less excitable during the SF task.

Brain activation during human finger extension and flexion movements

Corticospinal projections to the motor neuron pool of upper-limb extensor muscles have been reported to differ from those of the flexor muscles in humans and other primates. The influence of this difference on the central nervous system control for extension and flexion movements is unknown. Cortical activation during thumb extension and flexion movements of eight human volunteers was measured using functional magnetic resonance imaging (fMRI), which detects signal changes caused by an alteration in the local blood oxygenation level. Although the relative activity of the extensor and flexor muscles of the thumb was similar, the brain volume activated during extension was substantially larger than that during flexion. These fMRI results were confirmed by measurements of EEG-derived movement-related cortical potential. Higher brain activity during thumb extension movement may be a result of differential corticospinal, and possibly other pathway projections to the motoneuron pools of extensor and flexor muscles of upper the extremities.

Synthesis of glucose oxidase and catalase by Aspergillus niger in resting cell culture system

The synthesis of glucose oxidase and catalase by Aspergillus niger was investigated using a resting cell culture system without growth being established. Calcium carbonate induced the synthesis of both enzymes and calcium chloride inhibited it. The optimal pH for the biosynthesis of glucose oxidase and catalase was 6.0 and 5.7, respectively. The effects of other bivalent cations, reductive compounds and metabolic products on enzyme synthesis were also tested. The biosynthesis of glucose oxidase and catalase was promoted by MnCO3, thioglycolic acid, pyroracemic acid and gluconic acid.

Older adults exhibit a reduced ability to fully activate their biceps brachii muscle

BACKGROUND

Voluntary muscle strength declines significantly in older adults. One contributing factor to the strength loss is muscle atrophy developed in old age. Whether the ability to maximally activate the muscle decreases with age, however, is unknown. This study was intended to determine if the central nervous system command to maximally activate the biceps brachii muscle deteriorates with age.

METHODS

Electrical stimulation pulses were applied to the skin overlying the biceps brachii muscle during maximal voluntary elbow-flexion contractions. The magnitude of force evoked on the maximal voluntary force was measured to determine the activation level (AL) of the muscle.

RESULTS

The AL was 94% for the elderly group and 97% for the young group (100% AL indicates complete activation). The AL for both the elderly and young groups was significantly (p<.05) lower than 100%. The AL of the elderly group was significantly (p<.05) lower than that of the young group.

CONCLUSIONS

The loss of voluntary strength in older adults is a mixed result of muscle atrophy and a reduced ability to fully activate muscle.

Mutagenicity of urine from individuals exposed to LPG combustion products

The mutagenicity of urine from individuals exposed to the combustion products of liquefied petroleum gas (LPG) was detected with Salmonella typhimurium TA98 and its newly developed derivatives YG1021 (nitroreductase overproducing) and YG1024 (O-acetyltransferase overproducing). The detection showed significantly increased mutagenicity for the two YG strains and increased positive rates for all three strains in the presence of both rat liver S9 and beta-glucuronidase. Further analysis demonstrated that urine samples taken from smoking and non-smoking exposed individuals exhibited significantly higher mutagenic potency (revertants/10 microliters urine concentrate) than their corresponding controls. These results indicate that the increased urine mutagenicity is caused by the exposure to LPG combustion products or smoking. The mutagenic potency of urine samples of all exposed individuals tested with YG1024 was found to be about 7 times higher than with TA98. The difference in mutagenic potency was smaller for the same samples when comparison was made between YG1021 and TA98. This suggests that the mutagenic compounds present in the urine samples contain mainly aromatic compounds as glucuronide conjugates. Our results demonstrate that YG1024 is more sensitive than TA98 in detecting the mutagenicity of these samples. In addition, no significant difference in the mutagenic potency between the 'pure' exposed (non-smokers') and the 'pure' smokers' (unexposed) samples was found in all three tester strains. This might mean that the exposure extent of mutagens/carcinogens in LPG combustion products for exposed individuals roughly corresponds to the smoking level of smokers who smoke 20-40 cigarettes per day. Furthermore, the results also suggest that synergism might exist in the mutagenic effects of exposure to LPG combustion products and cigarette smoking.

Garlic powder and allyl sulfur compounds enhance the ability of dietary selenite to inhibit 7,12-dimethylbenz[a]anthracene-induced mammary DNA adducts

These studies examined the ability of garlic powder or allyl sulfur compounds to modify selenite protection against 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary epithelial cell DNA adducts. In Study 1, female rats (n = 5) were fed diets containing sodium selenite at 0.1, 0.5, or 1.0 mg Se/kg and garlic powder at 0, 20, or 40 g/kg diet. Total DNA adducts correlated inversely with selenite or garlic powder intake. Garlic powder enhanced the selenite inhibition of mammary DNA adducts. In Study 2, selenite (2.0 mg Se/kg diet), garlic powder (20 g/kg diet), water-soluble S-allyl cysteine (SAC; 5.2 mumol/kg diet), and oil-soluble diallyl disulfide (DADS; 5.2 mumol/kg diet) inhibited (p < 0.05) total DNA adducts by 45%, 40%, 80%, and 75%, respectively. Combining selenite with garlic powder, SAC, or DADS further inhibited DNA adducts. Selenite, but not garlic powder, SAC, or DADS, enhanced liver glutathione S-transferase and uridine diphosphate-glucuronosyltransferase activities. Selenite, garlic powder, SAC, or DADS did not affect liver cytochrome P-450 1A1 activities. The present studies provide evidence that synergistic protection against the initiation of DMBA carcinogenesis occurs when selenite is supplemented in conjunction with garlic or its allyl sulfur components.

Garlic and associated allyl sulfur components inhibit N-methyl-N-nitrosourea induced rat mammary carcinogenesis

Our previous studies demonstrated that dietary garlic powder supplementation inhibits N-nitrosamine induced DNA alkylation in liver and mammary tissue. The present studies compared the impact of dietary supplementation with garlic powder or two garlic constituents, water-soluble S-allyl cysteine (SAC) and oil-soluble diallyl disulfide (DADS), on the incidence of mammary tumorigenesis induced by N-methyl-N-nitrosourea (MNU). Female Sprague-Dawley rats were fed semi-purified casein based diets with or without supplements of garlic powder(20g/kg), SAC (57 micromol/kg) or DADS (57 micromol/kg) for 2 weeks prior to treatment with MNU (15 mg/kg body wt). Garlic powder, SAC and DADS supplementation significantly delayed the onset of mammary tumors compared to rats receiving the unsupplemented diet. Tumor incidence 23 weeks after MNU treatment was reduced by 76, 41 and 53% in rats fed garlic, SAC and DADS, respectively, compared to controls (P<0.05). Total tumor number was reduced 81, 35 and 65% by these supplements, respectively (P<0.05). In a separate study the quantity of mammary DNA alkylation occurring 3 h after MNU treatment was reduced in rats fed garlic, SAC or DADS (P<0.05). Specifically, O(6)-methylguanine adducts were reduced by 27, 18 and 23% in rats fed supplemental garlic, SAC and DADS, respectively, compared to controls. N(7)-Methylguanine adducts decreased by 48, 22 and 21% respectively, compared to rats fed the control diet. These studies demonstrate that garlic and associated allyl sulfur components, SAC and DADS, are effective inhibitors of MNU-induced mammary carcinogenesis.

Molecular epidemiology of factor IX germline mutations in Mexican Hispanics: pattern of mutation and potential founder effects

Germline mutations in patients with hemophilia B generally have arisen within the past 150 years. Evidence suggests that these germline mutations generally result from endogenous processes. However, a unique pattern would be expected if a population were exposed to a physiologically important germline mutagen since mutagens generally produce characteristic patterns, or "fingerprints", of mutation. To determine the pattern of mutation in Mexican Hispanics, the regions of likely functional significance in the factor IX gene were screened by dideoxy fingerprinting (ddF) in 31 families with hemophilia B. Mutations were found in 30 of these families. Haplotype analysis was performed on individuals with identical mutations to help distinguish independent, recurrent mutations from founder effects. Analysis of these 30 mutations, along with 7 mutations reported previously in Mexican Hispanic families, reveals a pattern of independent mutation that is similar to the pattern of mutation observed in 127 U.S. Caucasian families (p = 0.89). These results may reflect either an underlying pattern of germline mutation due to endogenous processes or the presence of an ubiquitous mutagen. Further analyses of the recurrent mutations revealed that two mutations, T296M and R248Q, accounted for 19% of the mutations found in the Mexicans. Haplotype data suggest that the multiple occurrences of T296M and R248Q are associated with founder effects and that screening for these mutations may allow rapid mutation detection and carrier diagnosis in a significant minority of Mexican families with hemophilia B, These two mutations also are associated with founder effects in the U.S, Caucasian population. However, the haplotypes are different in these two populations, indicating independent origins. The occurrence of identical founder mutations in distinct populations provides evidence for the previous hypothesis that the number of different mutations giving rise to mild or borderline mild/moderate hemophilia B is small compared to deleterious mutations causing more severe disease.

A study on the difference of human sensation evaluation to whole-body vibration in sitting and lying postures

The evaluation of vibration sensation is a problem which has large individual differences. In order to clarify the relationship between posture and psychological response, human sensation to whole-body vibration (from 2 to 11 Hz) in sitting and lying postures was evaluated by the semantic differential method, and the influences of posture on the evaluation were investigated by using the fuzzy measure. Furthermore, the paired t-test was used to test the significant differences in the results of evaluation between the two postures. The results were as follows: (1) Psychological responses of human beings to whole-body vibration were greatly affected by the postures. (2) Changes of the psychological responses in the lying posture were smaller than those in the sitting posture. (3) There were significant differences between sitting and lying postures in the evaluation results of physiological factor, psychological factor and synthetic evaluation (P < 0.025).

Mutagenicity and induction of drug-metabolizing enzyme activity by LPG combustion particulates in rats

Methylene chloride extracts of particulates from liquefied petroleum gas (LPG) combustion appliance were studied by using Ames test, micronucleus test and inducibility of pulmonary and hepatic aryl hydrocarbon hydroxylase (AHH) and glutathione S-transferase (GST) in rats. The extracts showed mutagenicity for Salmonella typhimurium strain TA98 and its derivatives TA98NR and TA98/1,8-DNP6 with or without S9 mix. The revertants in strains TA98NR and TA98/1,8-DNP6 were less than 40% and 50% of that in strain TA98 without S9 mix, respectively. Positive results were obtained in mouse bone marrow micronucleus assay. Intratracheal instillation of the extracts led to increase in pulmonary (but not hepatic) AHH and GST activities in rats. It was seen that AHH was more sensitive than GST to induction by the extracts.

[Experimental studies on changes in retinal enzyme activities under acute ocular hypertension in cat eyes]

The changes of 10 enzymatic activities of cat retinas and their blood vessels under acute ocular hypertension were systematically observed by enzyme histochemical methods. These changes were induced by the damage caused by retinal ischemia-reperfusion. The activities of the free radical scavengers, catalase and hydrogen peroxidase, were decreased, demonstrating that the excess of free radicals is one of the essential causes of the injury. The principles of treatment are besides lowering of intraocular hypertension, during retinal ischemic stage, oxygen and nutrients needed urgently should be supplied through extra-vascular route and during reperfusion stage, free radical scavengers ought to be given.

Dietary selenite modifies glutathione metabolism and 7,12-dimethylbenz(a)anthracene conjugation in rats

The present studies determined the impact of dietary selenite on glutathione homeostasis in liver and mammary tissue and its relationship to biliary excretion of 7,12-dimethylbenz(a)anthracene (DMBA) conjugates. In Experiment 1, liver and mammary tissue concentration of reduced glutathione (GSH) and activities of gamma-glutamylcysteine synthetase (GCS), glutathione reductase (GR) and glutathione S-transferases (GST) were positively correlated with tissue selenium concentration in female rats fed semipurified diets supplemented with sodium selenite (0.05 to 4 mg Se/kg). The magnitude of the response was dependent upon total selenite intake and the tissue examined. Glutathione peroxidase activity did not correlate with tissue GSH concentration. Because both selenite and BHT have been reported to elevate liver GSH, Experiment 2 compared these agents (4 mg Se/kg and 6 g/kg BHT/kg, respectively) on the biliary excretion of DMBA metabolites. Five major biliary DMBA conjugates, three GSH and two beta-glucuronide, were identified. Dietary addition of selenite or BHT enhanced the excretion of these DMBA conjugates by over 100% during the 15-h collection period. These investigations suggest that dietary selenium can alter the concentration of GSH and the activities of three glutathione-dependent enzymes in mammary and liver, accounting for part of the expanded biliary excretion of DMBA conjugates. Enhanced biliary loss of DMBA conjugates likely relates to the reported depression in DMBA binding to mammary cell DNA and the inhibition of DMBA carcinogenesis caused by dietary selenite.

Dietary garlic suppresses DNA adducts caused by N-nitroso compounds

The present studies examined the impact of a processed garlic powder on the in vivo occurrence of DNA adducts caused by N-nitroso compounds (NOC) in rats. Addition of 2% garlic powder to diets containing aminopyrine and sodium nitrite (each at 600 mg/kg) reduced the occurrence of both 7-N-methyldeoxyguanosine (7-N-mG) and 6-O-methyldeoxyguanosine (6-O-mG) adducts to rat liver DNA by approximately 55%; and over 80% when 4% garlic was provided. Dietary supplementation with garlic powder (2 and 4%) also reduced the occurrence of 7-N-mG and 6-O-mG adducts by approximately 40 and 60% respectively, in rats intubated with N-nitrosodimethylamine (150 mg/kg body wt). The quantity of 7-N-mG and 6-O-mG adducts in mammary tissue of rats given intravenous N-methyl-N-nitrosourea (50 mg/kg body wt) was reduced over 50% in rats fed 2% garlic compared to controls. The depression in the occurrence of these adducts was approximately 70% when dietary garlic was increased to 4%. These experiments suggest the reduction in DNA adducts caused by processed garlic powder likely reflects a depression in the formation of NOC from precursors and changes in the bioactivation and/or denitrosation of NOC.