Rupture propagation in a model of an earthquake fault.
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Biomedical subjects
Publications and source records attributed to C Tang.
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In a study of nursing home applicants, residential care decisions made by a multidisciplinary assessment team were examined. The team agreed that of the 296 applicants assessed, 54 per cent required the high level of physical and supportive care provided in a nursing home. Hostel care was recommended for 17 per cent, continuing care at home for 17 per cent, hospice care for 1 subject, and in 13 per cent of cases the team postponed their decision. A decision for nursing home care was associated with low Barthel Index of Activities of Daily Living scores, dementia, incontinence and the absence of a carer willing to continue care. A decision to delay was associated, in most cases, with a requirement for further in-patient assessment and/or rehabilitation, and therefore with a potential for functional improvement. A decision for hostel care instead of home care was associated with a low level of informal support and the absence of a carer who was a spouse or daughter. The findings suggest that a program of geriatric assessment will accurately identify the differing care needs of nursing home applicants. The initial value of such an assessment program may be to contribute to the planning of residential and other long-term care services rather than to reduce inappropriate nursing home admissions.
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The influence of oral lithium on the concentration of red blood cell choline (Ch), lecithin, glycerophosphorylcholine (GPCh) and phosphorylcholine (PCh) was studied. The concentration of RBC Ch was significantly elevated and the concentration of lecithin, GPCh and PCh significantly depressed in 16 patients on oral lithium compared to 9 age-matched controls. We conclude that lithium markedly depletes the red blood cell of choline containing compounds including lecithin. These changes may be responsible for both the therapeutic efficacy and the toxicity of lithium.
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We describe two cases of primary low-grade B-cell lymphoma of the thymus that showed histological features of low-grade B-cell lymphoma arising in mucosa-associated lymphoid tissue (MALT). The appearances most closely resembled MALT lymphoma arising in myoepithelial sialadenitis (MESA). In both cases, the tumor was excised. In one case, there has been no recurrence in 4 years of follow-up without further treatment; in the second case, the tumor has involved an axillary lymph node. Immunohistochemistry showed light-chain restriction in both cases, and the B-cell phenotype was similar to that previously described in MALT lymphomas. The occurrence of MALT lymphoma in the thymus is consistent with the presence of mucosal structures (Hassall's corpuscles) and with recent descriptions of a native B-cell population in this organ. The relationship of this previously undescribed thymic low-grade B-cell MALT lymphoma arising in the thymus has not yet been clarified.
Somatosensory evoked potentials (SEP) were recorded during and immediately following temporary middle cerebral artery (MCA) occlusion to determine whether they can be used to predict ischemic lesions to the somatosensory cortex (SI). Twenty-one cynomolgus female monkeys were subjected to four different MCA occlusion durations (15-60 min) during hypotension (45-50 mm Hg mean arterial blood pressure). The amplitude and central conduction time (CCT) of the median nerve SEP were recorded preceding, during, and following occlusion. Two groups were established based on the development of SI ischemic lesions: animals developing SI lesions formed the SI-lesion group (n = 9), and animals without ischemic lesions or with lesions outside the SI cortex formed the SI-spared group (n = 12). Changes in the SEP during and following MCA occlusion under conditions of hypotension were similar to those reported by others. The SEP disappeared in all animals within 15 min of occlusion and reappeared 5 min following reperfusion. Several differences were observed between the SI-lesion and SI-spared groups. The SI-lesion group had a more rapid decrease in SEP amplitude during the first 5 min of occlusion and had smaller SEP amplitudes and longer CCTs during reperfusion. These results suggest that changes in SEP amplitude and latency during and immediately following temporary MCA occlusion predict development of SI ischemic lesions.
We investigated the effect of deoxycorticosterone acetate (DOCA)-induced hypertension on plasma lipid and cholesterol levels and the development of vascular atherosclerotic changes in male Wistar rats injected with streptozotocin (STZ) or saline (CON). Rats given STZ alone demonstrated a mild hyperlipidemia and hypercholesterolemia without any change in blood pressure. One week of DOCA administration was without effect on blood pressure in CON and STZ groups, but at 3 and 6 wk caused a significant and similar elevation in both groups. This DOCA-induced elevation in blood pressure appeared to be associated with the increase in plasma lipid and cholesterol levels seen in both CON and STZ groups at 3 and 6 wk, although the elevation in lipid and cholesterol levels was significantly more pronounced in the STZ rats. Both CON and STZ groups injected with DOCA developed significant pathological changes in all vessels under investigation. However, the degree of atherosclerosis appeared, from a semiquantitative analysis, to be worse in the thoracic aortas and renal arteries of the STZ group. Neither normotensive group developed any atherosclerosis. It is concluded that hypertension is associated with atherosclerosis in normal rats and rats with short-term STZ-induced diabetes mellitus, although the higher plasma lipid and cholesterol levels of the latter group may potentiate the degree of vascular damage.
The effect of streptozocin-induced diabetes (STZ-D) on right atrial structure was investigated in male Wistar rats. STZ (55 mg/kg) or saline (1 ml/kg) was administered by intravenous injection 12 wk before the experimental studies. Tissue was sampled from four regions of the atrium, processed, and embedded in plastic. Quantitative stereological analysis indicated that in STZ-D rats, there was a significant diminution in size of the musculi pectinati (muscular ridges), which form a network making up the wall of the atrium. In addition, within the muscular ridges, there was a significant reduction in the relative proportion of cardiocytes within the cardiac tissue. The rest of the cardiac tissue consisted of interstitial regions, connective tissue, and blood vessels, which correspondingly increased. This suggests there was some form of cardiomyopathy. When atrial granularity was determined relative to cardiocyte volume density, a significant decrease (54%) was found in tissue from STZ-D rats. The blood pressure of conscious STZ-D rats was significantly lower than control rats, whereas right atrial pressure was not different. The level of resting plasma immunoreactive atrial natriuretic factor (ANF) in conscious STZ-D rats (98 +/- 5 pg/ml) was significantly higher than in control rats (52 +/- 7 pg/ml). The decreased atrial granularity could be related to the higher resting plasma ANF levels, suggesting a more rapid turnover or increased synthesis bypassing storage in the granular form.
The synthesis of 16 compounds of N, N-alkylene-bis (substituted phenol) glycine is reported. They showed good effects on the removal of redinuclide thorium-234 from rats, except compound 3 and compound 4. Two of them can remove more than 70% of injected thorium. The relationship between structure and effects of these compounds was discussed.
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Between August 1976 and May 1988, 43 patients had their heart valve prostheses replaced. The total mortality was as high as 25.6%, but the operative mortality was reduced to 6.25% in the last 16 cases. The indications, main risk factors and surgical techniques are discussed.
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Choline concentrations in human erythrocytes increase after freezing and thawing, during incubation in Krebs-phosphate for 30 min or on storage at 0 degrees C for 3-24 hr. The increase is prevented by protein precipitation by 10% perchloric acid, 10% zinc hydroxide, 10% sodium tungstate or boiling in water. It is not prevented by EDTA (10 mM) and is increased by oleate (5 mM). We suggest that the increase is due to the action of phospholipase D on erythrocyte phospholipids.
The aim of this study was to determine the duration of middle cerebral artery occlusion required to produce significant ischemic damage when the occlusion occurs during controlled systemic hypotension. In 21 anesthetized cynomolgus monkeys, an IV infusion of sodium nitroprusside was used to lower the mean arterial blood pressure to 45-50 mmHg for 90 minutes. Middle cerebral artery occlusion for 15, 30, 45, or 60 minutes was performed during the hypotensive period. Neurological function was then evaluated every 8 hours for a total of 72 hours. At the end of the observation period, the monkeys were again anesthetized, magnetic resonance imaging was performed, and the brain was perfused with 10% buffered formalin. Neurological deficits were observed after 30 minutes, but not after 15 minutes, of middle cerebral artery occlusion, and rapidly increased in incidence and severity when the duration of occlusion was increased. After 60 minutes of occlusion, all the monkeys exhibited severe deficits. Four monkeys died during the observation period--two in each of the 45- and 60-minute occlusion groups. Histopathological examination revealed that little or no ischemic damage resulted from a 15-minute occlusion during hypotension. However, severe ischemic damage began to occur after only 30 minutes of occlusion, and all monkeys subjected to middle cerebral artery occlusion for 60 minutes developed extensive regions of infarction. The size and incidence of these infarctions correlated well with the lesions observed in the magnetic resonance images. These results demonstrate that the duration of middle cerebral artery occlusion that produces cerebral infarction in primates is drastically reduced when the occlusion occurs at hypotensive levels commonly employed during neurovascular surgical procedures.