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.

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.

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.

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.

Polarization pinhole interferometer

A polarization pinhole interferometer is based on the principles of pinhole diffraction, a common light path, and the polarization technique in its design. It has many advantages, such as adjustable contrast of the fringes, nondestructive testing, and less sensitivity to environmental factors. The instrument can be used extensively in optical element testing and glue-layer testing. The accuracy of the fringe pattern analysis is controlled by the number of sampled points in the fringes. The analysis results of the closed fringe pattern are given.

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.

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.

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.

[Anti-tumor effect of Cetraria laevigata Rassad. polysaccharides]

The anti-tumor effect of Cetraria laevigata polysaccharides has been investigated in mice using sarcoma 180; Ehrlich ascitic tumor, cervical carcinoma u-14 and leukemia L7217. The results show that Cetraria laevigata polysaccharides may inhibit the growth of sarcoma 180, Ehrlich ascitic tumor and cervical carcinoma u-14 in mice at a dose of 200mg/kg ip (1/5 LD50). However, the survival time of leukemia L7217 wasn't prolonged. The reticuloendothelial system phagocytic function in mice was increased at ip doses of 50 mg/kg and 100 mg/kg (1/10 and 1/20 LD50).

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.

Improved heart and lung preservation in a rat model

We investigated the efficacy of four different preservation solutions in a heart-lung model in the rat. The heart and lungs of the donor were perfused under standardised conditions of temperature, pressure and flow. We studied 4 groups: group 1 received Stanford solution to heart and lung; group 2 received St. Thomas' solution to heart and Papworth solution to lung; group 3 received University of Wisconsin solution to heart and lung; and group 4 received University of Wisconsin solution to heart and Papworth solution to lung. Lung function assessed by arterial pO2 at a standardised FIO2 was significantly better in groups 2 and 4 than in other groups. However, cardiac function as assessed by cardiac output, stroke work index and minute work index was significantly better in group 4 than in any other group. Overall, the combination of solutions in group 4 provided the most effective preservation in this model.

Two-way shuttlebox avoidance conditioning and brain NADH in rats

The effects of amphetamine (1.5 mg/kg) and caffeine (120 mg/kg, 75 mg/kg) on shuttle behavior and on the concentrations of reduced nicotinamide adenine dinucleotide (NADH) of the brain were studied in 56 rats from the perspective of regional brain metabolism. Amphetamine potentiated the shuttle behavior including avoidance responses and response speed, while it increased NADH concentrations in the hippocampus. The low dose of caffeine increased avoidance responses. The high dose of caffeine inhibited avoidance responses, but it had no effect on NADH concentrations in discrete brain regions.

[Studies on the toxicity of a new synthetic drug SC1001-aminum]

SC1001A is a new sedative, hypnotic and anti-epileptic drug. Screening for possible mutagenicity of the agent consisted of a battery scheme of short-term mutagenic tests with different hereditary detecting end points. Three assays were with in the scheme: Ames test (for detecting gene mutation in vitro), micronucleus test (for detecting chromosomal aberration in vivo) and CHL (Chinese hamster lung cell line) test (for detecting chromosomal aberration in vitro). In addition, a routine teratogenicity study on SC1001A was carried out in mice. They were given daily at 3-dose levels (exposed to up to 33% of the LD50 by gastric incubation from the 6th through the 15th day of gestation. SC1001A gave uniformly negative results in all three mutagenic assay systems. Results of the teratogenic experiment showed that only the pregnant rate in bred mice in the moderate dose group and the mean maternal body weight gain of the dams during gestation in the low dose group were significantly lower than those in the corresponding control group. A clear dose-response relationship was not demonstrated. All dose levels of SC1001A used caused no adverse effects on the number of survival fetuses per litter, growth or development of the fetal mice. No malformations in the external appearance, of the internal organs and of the skeletal systems in fetal mice were observed. The above-mentioned results indicated that SC1001A induced neither gene mutation nor chromosomal damage both in vitro and in vivo. There was no evidence of teratogenesis. Therefore, it is estimated that SC1001A is probably comparatively safe as a pharmaceutical product for human beings in usual dosage.

[Studies of the determination of selenium by hydride generation atomic absorption spectrometry]

Potassium ferricyanide has a masking effect of Cu2+, Ni2+ and other interferential ions in the determination of selenium by hydride generation atomic absorption spectrometry. Interference was not observed in the determination of 5ng/ml of Se(IV) in the presence of 10micrograms/ml of Cu2+ under recommended conditions. The stability of analyte and potassium borohydride solutions in storage was also studied.