Leprosy--economy--environment; might we predict leprosy incidence from this point of view?
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China↗
Biomedical subjects
J Zhong
Publications and source records attributed to J Zhong.
Clinical application of acupoint renying (St 9).
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Acupuncture Points↗
Nicotine inhibition of apoptosis suggests a role in tumor promotion.
Recent evidence indicates that cell death through apoptosis may be an important mechanism to prevent tumor development. Therefore, agents that inhibit apoptosis may function as tumor promoters. The purpose of this study was to determine the effects of nicotine on the process of apoptosis. The results demonstrate that nicotine inhibits apoptosis induced by diverse stimuli including tumor necrosis factor (TNF), UV light, chemotherapeutic drugs, and calcium ionophore. This phenomenon was observed in normal and transformed cells derived from a variety of species and tissues, including tumor cell types related to tobacco use. The major nicotine metabolite, cotinine, also inhibited apoptosis, whereas N-nitrosodiethylamine, a carcinogen found in tobacco, was without effect. Therefore, nicotine-mediated inhibition of apoptosis may contribute to the pathogenesis of tobacco-related cancer as well as decrease the efficacy of cancer therapies.
Animals↗
Polaronic anharmonicity in the Holstein-Hubbard model.
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Journal Article↗
Factors influencing contrast in fast spin-echo MR imaging.
Multi-echo pulse sequences for producing T2-weighted images in much reduced imaging times have recently been developed for routine clinical use. A number of recent articles have described the contrast obtained with fast spin-echo (FSE) sequences and have generally indicated that they depict tissues very similarly to conventional spin-echo (SE) imaging. There are, however, some important differences in contrast between some tissues in FSE images. This work presents a detailed study of the contrast obtained with FSE imaging sequences and examines the image sequence and tissue parameters which influence contrast. The use of multiple refocusing pulses produces several subtle effects not seen in conventional SE imaging sequences, and in this study the precise nature and extent of such effects are described. The relative contributions to image contrast of magnetization transfer, the decoupling of J-modulation effects, the production of stimulated echoes and direct saturation effects, of diffusion and of the effects of the differential attenuation of different spatial frequencies, are each quantified. The mechanisms responsible for the brighter fat signal seen in FSE images, as well as the loss of signal from some other tissues, are explained. Computer simulations, phantom experiments, and clinical images are all used to support the conclusions.
Brain↗
[The immunologic studies on experimental heterogeneous penetrating keratoplasty].
Using the experimental model of chicken-rabbit penetrating corneal grafting, micro-whole-blood 3H-TdR incorporation and ELISA the authors dynamically observed the functional state of cellular and humoral immunities for 10 weeks after operation. The results showed, (1) In both the homogroup and the hetero-group, the transformational degree of lymphocytes in peripheral blood increased, most obviously in the 3rd or 4th week postoperatively. (2) In the hetero-group, specific anti-corneal antibody appeared obviously in the serum during 2-8 weeks postoperatively. Combined with morphologic observation, it has proved that: (1) The immune rejection is mainly cellular mediated immunoresponse, meanwhile, the humoral immunoresponse also participates in it, and the humoral immunoresponse participates in the heterokeratoplasty more obviously. (2) Applying the micro-whole-blood 3H-TdR incorporation is capable of determining the immunologic state of the body after corneal transplantation. (3) Attention should be focused on the 3-4 week period postoperatively when immunosuppressive-agent is administered.
Animals↗
Inhibitory effect of rhynchophylline on platelet aggregation and thrombosis.
Rhynchophylline (Rhy) inhibited rabbit platelet aggregation induced by arachidonic acid (AA), collagen, and ADP. The values of IC50 were 0.72, 0.74, and 0.67 mmol.L-1, respectively. Rhy reduced the thromboxane B2 (TXB2) generation in PRP induced by collagen but failed to reduce that induced by AA. Rhy suppressed malondialdehyde (MDA) formation in platelet suspension stimulated by thrombin, inhibited the platelet factor 4 (PF4) release. It did not alter intraplatelet cAMP concentration. Rhy 10-20 mg.kg-1 iv showed a significant inhibition of venous thrombosis and cerebral thrombosis in rats.
Alkaloids↗
Clinical and experimental studies on tong yu ling in the treatment of diabetic hyperlipemia.
72 diabetes mellitus patients (70 cases non-insulin-dependent) were treated routinely with D860. After one month, cases with persisting hyperglycemia and hyperlipemia were randomly divided into Group A to be treated with D860 plus Tong Yu Ling (TYL), and Group B to continue treatment with D860 alone, while Group C, comprising cases with persisting hyperlipemia only, were treated with TYL alone. Therapeutic results showed that of the total 50 cases of Group A and C, 26 were markedly improved, 14 improved, and 10 cases ineffective. The antihyperlipemic effect was pronounced in Group A, where the blood cholesterol, beta-lipoprotein and triglyceride showed remarkable decline, less pronounced in Group C, and insignificant in Group B. Experiments in rat models of non-insulin-dependent diabetes demonstrated that TYL was markedly effective in treating hyperlipemia.
Adult↗
On the relative importance of paramagnetic relaxation and diffusion-mediated susceptibility losses in tissues.
Susceptibility agents such as dysprosium may reduce the apparent T2 of a tissue by inducing magnetic field gradients so that diffusion of water molecules causes dephasing of the transverse magnetization. Gadolinium has a susceptibility that is about 30% lower than dysprosium, so that diffusion losses are expected to be only half as big, but it also may produce paramagnetic relaxation by dipolar interactions. The relative importance of these two processes is dependent on several parameters, including the metal concentration, pulse sequence timing, field strength, and the permeability of tissue interfaces to water exchange. The conditions under which exchange-mediated dipolar interactions are less important than diffusion losses have been derived for capillary borne contrast agents in realistic situations.
Capillary Permeability↗
Acupuncture treatment in 96 cases of superior cluneal nerve injury.
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Acupuncture Therapy↗
[Nasal breathing pressure and the flow test].
The evolution of nasal breathing pressure and a flow test had been introduced. Five abnormal types of nasal function were analyzed. The test is very useful to rhinologists by offering an objective diagnostic information, it is also useful to physicians and other medical workers, because nasal activities is related to cardio-pulmonary-vascular function.
Adult↗
[Snail distribution and susceptible zones of schistosomiasis in endemic areas around Poyang Lake].
To understand the situation of snail distribution and to explore the criteria of susceptible zones of schisosomiasis in endemic areas around Poyang Lake, a total of 1,222,910 mu of marshland in lake regions were surveyed for three years from 1982 through 1984 by 400 skillful observers. This article reports the relation between mean density of infected snails and incidence of acute schistosomiasis in marshland. We divided all susceptible marshlands of Poyang Lake area into three types, and found that about one fourth of the area belongs to the first type of susceptible zones, i.e., with high risk to schistosomiasis infection. Longitudinal observation showed that the types of susceptible zones changed very little unless measures of schistosomiasis control were taken. The results of field study suggested that we should put stress of schistosomiasis control on the first type of susceptible marshlands of Poyang Lake in future.
Animals↗
NMR relaxation of water in hydrogel polymers: a model for tissue.
The NMR relaxation rates of a class of hydrated polymers (hydrogels) have been investigated over a wide range of frequencies (0.01 to 60 MHz) and compositions. The gels comprise long chains of polytetramethylene oxide diol crosslinked by copolymers of dimethylacrylamide and methylmethacrylate. The longitudinal relaxation rate dispersion curves of these materials are very similar to those shown by human tissues and they can be altered in flexible fashion by changing the polymer content. By substitution of the water by deuterium oxide, the contribution of intermolecular cross-relaxation effects has been shown to account for two-thirds the total water relaxation rate. With their close similarity to tissue relaxation behavior, hydrogels of differing compositions are particularly well-suited to MRI phantoms and test objects.
Hydrogel, Polyethylene Glycol Dimethacrylate↗
Inhibition of carnitine acetyltransferase by metabolites of 4-pentenoic acid.
The inhibition of carnitine acetyltransferase (EC 2.3.1.7) by metabolites of 4-pentenoic acid was studied. 3-Keto-4-pentenoyl-CoA, a beta-oxidation metabolite of 4-pentenoic acid, was found to be an effective inhibitor of the enzyme in the presence, but not in the absence of L-carnitine. Since acetyl-CoA protects the enzyme against this inhibition, 3-keto-4-pentenoyl-CoA seems to be an active site-directed inhibitor. 3-Keto-4-pentenoyl-CoA, which is a substrate of carnitine acetyltransferase, causes the irreversible inactivation of the enzyme. All observations together lead to the suggestion that 3-keto-4-pentenoyl-CoA is a mechanism-based inhibitor of carnitine acetyltransferase.
Acetyltransferases↗
Diffusion-weighted imaging in tissues: theoretical models.
Typical diffusion measurements use Stejskal-Tanner pulsed gradient spin echo sequences to provide information about the average diffusion and displacement profiles of particles in a sample. To derive structural information, a measured displacement profile has to be related by means of a model to the physical and geometrical properties of the tissue, such as diffusion coefficients and shapes of semi-permeable membranes of compartments in the system. The behavior of the NMR signal and the measured ADC are greatly affected by the cellular architecture of a tissue, mainly because cellular membranes are relatively impermeable to water. For long diffusion times, and small signal attenuations, ADC is relatively insensitive to how it is measured. In general, however, ADC values are not readily interpreted unless the measuring conditions are specified in detail. For given measuring conditions, ADC depends on intra- and extracellular diffusion coefficients, membrane permeabilities, cell sizes and the cellular volume fraction. If intra- and extracellular T2 relaxation rates are different enough, ADC may also depend on the relaxation properties of the system and the echo time. An improved understanding of the precise influence of these factors has been obtained by detailed consideration of theoretical and computer models that can be related to experimental data in simple systems. Further refinements of such models should advance our understanding of water diffusion in tissues.
Body Water↗
Diffusion-weighted NMR imaging changes caused by electrical activation of the brain.
The apparent diffusion coefficient of brain water was decreased by frontal cortical electroshock, usually but not always associated with brief epileptic afterdischarge detectable at the parietal cortex. Previous studies have shown that status epilepticus causes similar larger decreases, which are largely reversible by the termination of seizure discharge with pentobarbital. Cerebral blood flow is elevated in these conditions, and biochemical energy failure does not occur. The brain water diffusion coefficient also decreases in spreading depression, without depletion of energy stores. All of these findings may be due in part to the reduction of brain extracellular space caused by cell swelling, which occurs to some degree in all three conditions. However, major biological differences between brain activation and brain ischemia and new evidence for increased cytosolic viscosity in the latter both suggest that other mechanisms deserve further investigation. Use-dependent motility of dendritic spines and other phenomena that may allow direct detection of neural activity by diffusion-weighted NMR imaging are of special interest.
Animals↗
Improved microplate fluorometer counting of viable tumor and normal cells.
An improved method has been developed to count cells in situ based on the measurement of esterase activity with carboxyfluorescein diacetate. This sensitive, semiautomated microplate fluorometer assay was able to estimate viable cell numbers over a range of 5 x 10(2) to 2.6 x 10(5) cells/well in a tumor cell line. Sensitivity to 10(3) was demonstrated in two other cell lines. Sub- and supranormal fluorescence events which can be responsible for unreliable readings when using a fluorescence assay for cell counting were quantified in a menadione (cytotoxic agent)/U-87 MG (cell line) model. There was a close correlation between the fluorometer method and Coulter counter method for two different tumor cell lines when this method was performed on cells after sub- and supranormal fluorescence events had ceased.
Cell Count↗
Urinary excretion of nitrosamino acids and nitrate by inhabitants of high- and low-risk areas for nasopharyngeal carcinoma in southern China.
The hypothesis that endogenous synthesis of nitrosamines from dietary precursors is a risk factor for nasopharyngeal carcinoma (NPC) in China was tested by applying the nitrosoproline (NPRO) test to subjects living in high- and low-risk districts for NPC in Zangwu county, Guangxi region, in southern China. Samples of 12-h urine were collected from 77 subjects: (a) before any treatment; (b) after ingestion of proline; and (c) after ingestion of proline together with vitamin C. NPRO, other nitrosamino acids, and nitrate were measured as indices of exposure to preformed and endogenously formed nitrosamines or their precursors. The NPRO level after proline intake was significantly increased in subjects from the high-risk area (P = 0.012) and markedly reduced after ingestion of ascorbic acid (P = 0.007), but such an effect was not seen in subjects from the low-risk area. Levels of N-nitrosothiazolidine-4-carboxylic acid and the sum of nitrosamino acids in subjects in the high-risk area were significantly reduced by ascorbic acid (P < 0.01) but were not reduced in subjects from the low-risk area. The urinary nitrate level was about twice as high in subjects from the high-risk area. In subjects from high- and low-risk areas combined, NPRO levels in any of the three dose groups were highly correlated with nitrate levels (P = 0.0001). These results demonstrate a higher potential for endogenous nitrosation in subjects living in the high-risk area of NPC and suggest the occurrence of nitrosation inhibitors in the diet consumed in the low-risk area.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗