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Biomedical subjects

G Wang

Publications and source records attributed to G Wang.

At least 811 records · Page 45Linked to original sources
PubMed1992

[Analysis of chemical constituent of essential oil in Lonicera japonnica Thunb. cultivated on the northern plain of Henan Province].

The chemical constituents of the essential oil in the dry flower and fresh flower of Lonicera japonica were analyzed by the GC-MS-DS technique and the superimposition of authentic samples. 27 and 30 monoterpenoids and sesquiterpenoids were identified from the essential oil of the dry flower and fresh flower respectively. The major constituents have been found to be linalool, geraniol, aromadendrene and eugenol etc.

Acyclic Monoterpenes↗
PubMed1992

A non-linear method for estimating the alpha generators from an EEG over the scalp.

A method is developed to estimate the frequency feature of alpha generators from EEG signals of different derivation. This method is based on principal component analysis and a constrained non-linear optimization technique. Results of the method gives a variation range of the power spectrum. Experimental results for estimating the generator spectra of the brain alpha activity in anterior and posterior regions over the scalp are shown. Finally, the noise problem with this method is also discussed.

Adult↗
PubMed1992

[The toxicity of herbicide Asulam].

We conducted a series of toxicity tests and short-term mutagenic assays of Asulam and 40% (W/V) sodium Asulam. It was found that the LD50 of Asulam with acute oral toxicity was 30000 mg/kg for mice, and the LD50 of sodium Asulam for mice and rats were equal (8250 mg/kg). The cumulative coefficient of sodium Asulam in Wistar rats was 9.42. None died from sodium Asulam absorbed via skin. Negative results were obtained in Ames test, Bacillus subtilis repair test and the micronucleus test. There was no significant difference between the control group and the treated groups in the chromosomal aberration rates of spermatogonia and primary spermatocytes of mice testis. The results indicated that Asulam should be regarded as a substance of low toxicity and low accumulation. No mutagenicity was observed in our experiment.

Animals↗
PubMed1992

[A method of mercapto cotton/Ag-DDC determination for inorganic arsenic in seafood].

A method of mercapto cotton/Ag-DDC determination for inorganic arsenic in seafood was developed. It is reliable and simple--The coefficients of variation for 1.0-5.0 micrograms As (III), kelp and dried small shrimp samples are 1.5-5.6%, 4.4% and 9.5%, respectively. The recoveries of kelp and dried small shrimp samples are 82.0-102.6% and 83.0-97.1%, respectively. As compared with the results of the extraction method (Government standard) in the determination of inorganic arsenic levels in 10 kinds of seafood, the results of this simple method showed no significant difference.

Animals↗
PubMed1992

A data reconstruction system for EEGs recorded on paper.

More efficient image skeletonization techniques can lead to a reduction in the distortion of EEG images and high precision of data reconstruction. We have developed and improved a system by which EEGs recorded on paper can be converted to computer treatable digital data. The performance of the system was evaluated and it was found to have excellent EEG data reconstruction ability. The system makes it possible to apply various computer analyses to EEGs recorded on paper.

Algorithms↗
PubMed1991

NMDA antagonist neurotoxicity: mechanism and prevention.

Antagonists of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptor, including phencyclidine (PCP) and ketamine, protect against brain damage in neurological disorders such as stroke. However, these agents have psychotomimetic properties in humans and morphologically damage neurons in the cerebral cortex of rats. It is now shown that the morphological damage can be prevented by certain anticholinergic drugs or by diazepam and barbiturates, which act at the gamma-aminobutyric acid (GABA) receptor-channel complex and are known to suppress the psychotomimetic symptoms caused by ketamine. Thus, it may be possible to prevent the unwanted side effects of NMDA antagonists, thereby enhancing their utility as neuroprotective drugs.

Animals↗
PubMed1991

Amplification by the polymerase chain reaction of a specific target sequence in the gene coding for Escherichia coli verotoxin (VTe variant).

Synthetic oligonucleotide primers were used in a polymerase chain reaction (PCR) protocol to target a specific sequence in the gene coding for the A subunit of Escherichia coli verotoxin (VTe-variant, VTev). This PCR protocol permits the VTe-variant target sequence to be distinguished from closely related sequences in the same coding regions for type 1, type 2, and type 2 variant E. coli verotoxins. This procedure will be a valuable adjunct to other DNA amplification techniques currently being used for molecular epidemiological studies of verotoxigenic E. coli.

Bacterial Toxins↗
PubMed1991

Evidence for the generation of hydroxyl radicals from a chromium(V) intermediate isolated from the reaction of chromate with glutathione.

The formation of hydroxyl radicals from a chromium(V) complex isolated from the reaction of glutathione with chromate has been demonstrated in spin trapping experiments using dimethylsulfoxide and 3,5-dibromo-4-nitrosobenzene sulfonate. Mechanisms for the formation of radicals in such systems are discussed. These results help to explain the ability of solutions containing chromate and glutathione to cause strand breaks in DNA.

Chromates↗
PubMed1991

The effects of hearing impairment on health services utilization.

The objective of this study was to examine the effects of hearing impairment on the utilization of physician and hospital services in the U.S. adult population. Andersen's behavioral model of health services utilization served as the conceptual framework for the study, and data used for the analyses were taken from two years (1971, 1977) of the Health Interview Survey. Hearing impaired persons used significantly more physician services than hearing persons. Hearing impairment had no effect on the number of hospitals days used but had a significant, positive effect on hospital contact and hospital episodes. In addition, neither the type nor the severity of the impairment had a consistent effect on utilization. These findings were consistent for both years of study data. The study's findings, implications, and suggestions for future research are discussed.

Health Services↗
PubMed1991

Analysis of EEG changes between the frontal and occipital cortex during speech.

A method of spatiotemporal analysis, using time series analysis techniques to represent activity in multiple brain regions, was applied to the interpretation of EEG information changes between the frontal and occipital areas during speech. This paper proposes and discusses a bidirectional communication model between the frontal and occipital cortices. Entropy analysis was introduced and used to simplify the calculation of transinformation in two dimensions. In this work, transinformation with direction between the frontal and occipital cortices before and during speech was investigated quantitatively for 11 subjects. The dominant information flow in the occipital-frontal direction was found immediately before speech in the right hemisphere. During speech, the dominant information flow was found in the occipital-frontal direction in both the right and left hemispheres. These results suggest that the method used in our work is feasible to analyze EEG signals in language processes.

Brain↗
PubMed1991

Identification of verotoxin type 2 variant B subunit genes in Escherichia coli by the polymerase chain reaction and restriction fragment length polymorphism analysis.

A set of synthetic oligonucleotide primers was designed for use in a polymerase chain reaction protocol to specifically detect the B subunit genes in vtx2ha and vtx2hb, which code for the production of the VT2 (Shiga-like toxin II) variant cytotoxins VT2v-a and VT2v-b, respectively. An additional set of primers amplified a fragment common to the B subunits of the VT2 and the VT2 variant genes. Subsequent restriction endonuclease digestion of this amplicon permitted prediction of specific VT2 and variant genotypes on the basis of predetermined restriction fragment length polymorphisms. Genotypes of 21 VT2-producing strains of Escherichia coli were determined using this polymerase chain reaction-restriction fragment length polymorphism procedure. Four strains contained B subunit target sequences only for VT2 genes, 9 strains contained sequences only for VT2v-a genes, and 3 strains contained sequences only for VT2v-b. For genes in combination, one strain contained B subunit genes for both VT2 and VT2v-a and two strains contained B subunit genes for VT2 and VT2v-b. Two strains of E. coli O91:H21 contained both VT2v-a and VT2v-b B subunit genes. The VT2 reference strain of E. coli, E32511, was found to contain the targeted sequences from both VT2 and VT2v-a genes, whereas the recombinant E. coli, pEB1, possessed only that of the VT2 gene. The specific activities of extracellular VT2 determined in HeLa cells ranged from 0.3 to 41.7 TCD50 per microgram of protein in strains carrying the VT2 gene target and from 0 to 50.0 TCD50 per microgram of protein in strains carrying only the VT2 variant target (TCD50 is the tissue culture dose by which 50% of the cells were affected), suggesting that phenotypic expression does not correlate with genotype.

Animals↗
PubMed1991

Biomechanical study of the bile duct system outside the liver.

Diseases of the bile duct system in the digestive system after surgery are common. In order to clarify the cause of these diseases, research on the diseases from a biomechanical perspective is increasing; however, the same cannot be said of biochemical research. In this paper, by using a new, well-devised testing apparatus, specimens extracted from the bile duct system of canine body are tested. The test data are analyzed using the finite deformation theory, and mechanical properties of the bile duct system outside the liver are investigated. The conclusions show that the viscoelasticity of the bile duct system is very small. In its normal physiological condition, the bile duct wall has an almost uniform distribution of circumferential and longitudinal stress. However, when the diseases of the bile duct system cause high pressure at the bile duct, the circumferential stress and longitudinal stress at the bile inside wall suddenly increase and are much larger than those stresses at the outside wall. The elastic modulus gradually becomes small from the common bile duct and the common hepatic duct to hepatic duct, and the value of elastic modulus for the cystic duct is almost equal to that of the hepatic duct.

Algorithms↗
PubMed1991

A staging of bone-marrow-derived osteosarcoma of long bones with a 64-case analysis.

According to the natural development of the bone-marrow-derived osteosarcoma (BMDOS) of long bones, it was classified into 4 stages. Stage A: The tumor is confined within the marrow cavity; stage B: The tumor has perforated the bone cortex; stage C: The tumor has involved the contiguous joint cartilage; and stage D: The tumor has metastasized to the lung. According to this staging, 64 cases of BMDOS of the long bones were investigated and the relationship between staging and prognosis, between different kinds of treatment and prognosis, etc. were analyzed. This staging of BMDOS of long bones proved to be very significant clinically. Only those cases in stage A or B can be expected to survive for 5 years; and because most of the non-survivors die within 2.5 years after treatment, this time is considered a critical period. Tumor involvement of the contiguous joint cartilage is also a critical sign. As to prognosis, the stage of the tumor is a more accurate indicator than is the method of treatment. And finally, the prognosis of patients treated with chemotherapy and amputation was generally better than that of patients treated by amputation alone.

Adolescent↗