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Biomedical subjects

C Yuan

Publications and source records attributed to C Yuan.

At least 19 recordsLinked to original sources
PubMed1992

A consistent model of insulin-dependent diabetes mellitus hypertension.

Hypertension is frequently seen in insulin-dependent diabetes mellitus (IDDM), but the mechanism of the hypertension is unknown. An animal model of IDDM hypertension could be helpful in determining the mechanism, but experimental IDDM has been infrequently and irregularly associated with hypertension. In an attempt to develop a consistent model of IDDM hypertension, we superimposed streptozotocin (STZ)-induced IDDM on surgical reduction of renal mass (RRM) in Wistar rats. Seven groups of rats were studied: 1) 60% RRM receiving 65 mg/kg body weight (BW) STZ; 2) 60% RRM receiving 40 mg/kg BW STZ; 3) 25% RRM receiving 65 mg/kg BW STZ; 4) two kidney normal rats receiving 65 mg/kg BW STZ; 5) 60% RRM receiving vehicle (control for group 1); 6) 60% RRM receiving vehicle (control for group 2); and 7) 25% RRM receiving vehicle. STZ produced diabetes and hypertension within 1 to 2 weeks in all three groups of RRM rats but blood pressure was unaffected by 60% or 25% RRM alone. STZ alone had no effect on blood pressure until the 5th week when the blood pressure increased slightly. Progressive weight loss resulted from 65 mg/kg BW STZ combined with 60% RRM; the animals had to be terminated after 5 weeks. In only 60% of animals with 40 mg/kg BW STZ plus 60% RRM was IDDM produced. On the other hand, 65 mg/kg BW STZ in rats with 25% RRM regularly produced IDDM and hypertension without excessive loss of body weight. In these rats, albuminuria developed in 2 weeks. Extracellular fluid volume was elevated and plasma renin activity was depressed. The animals were healthy and hypertensive when killed at the 13th week. We suggest that the 25% RRM rat receiving 65 mg/kg BW STZ is a consistent model of IDDM hypertension, which may be useful in probing the mechanism of this type of hypertension.

Albuminuria↗
PubMed1992

[Analysis of factors influencing on the surgical results of arterial embolism in the lower extremities].

130 patients with arterial embolism in the lower extremities underwent surgical treatment. The curative rate was 66.9%, amputation rate-19.2% and the mortality rate-13.8%. Statistical study showed that sex, age and recurrent embolism had few effects on the surgical results (P < 0.05). One of the influencing factors was the ischemic time of the lower extremities. The mortality rate was 33.3% in the distal abdomen with aortic embolism and 8.7% in the lower extremities (P < 0.005). The mortality rate and amputation rate were significantly higher in embolic patients with atherosclerotic stenosis and occlusion (9% and 17%). The mortality rate and amputation rate were 2.3% and 3.4% in patients with good blood flow and were 42.1% and 57.9% in patients without good blood flow uspectively. Reembolectomies showed no satisfactory effect. The results indicated that embolectomy combined with other necessary operations did not increase the mortality rate and amputation rate (P < 0.05). Postoperative anticoagulation therapy is extremely important.

Adolescent↗
PubMed1992

[Chemical constituents of the roots of Ostericum grosseserratum (Maxim.) Kitag].

This paper reports the isolation of eleven compounds from the roots of Ostericum grosseserratum, of which nine compounds were elucidated as myristic acid, palmitic acid, stearic acid, octacosanoic acid, succinic acid, beta-sitosterol, sitosterol-beta-D-glucoside, isoscopletin and sucrose. The results are helpful in the study of plant taxonomy.

Drugs, Chinese Herbal↗
PubMed1992

[Hepatic segmentectomy using microwave tissue coagulator].

Hepatic segmentectomy using a microwave tissue coagulator guided by intraoperative ultrasonography is a new operative procedure, which our research unit was the first to start using from 1990. Up to now we have performed this kind of operation with success in 26 cases. Our results suggested that the new procedure simplified the original operation and greatly reduced the risk of hemorrhage and iatrogenic spread of the cancer cells during operation. Besides, this operation as a kind of definite anatomic hepatectomy can minimally resect the tumor bearing tissue in a radical fashion, while maximally preserve the tumor-free tissue of the liver.

Adult↗
PubMed1991

MR angiography by multiple thin slab 3D acquisition.

Multiple overlapping thin 3D slab acquisition is presented as a magnitude contrast (time of flight) technique which combines advantages from multiple thin slice 2D and direct 3D volume acquisitions to obtain high-resolution cross-sectional images of vessel detail. Details of implementation and example images are presented.

Blood↗
PubMed1991

Sympathoadrenal excitation and inhibition by lower brainstem stimulation in cats.

Effects of stimulation of brainstem sites on hemodynamics and plasma catecholamine levels were assessed in cats under chloralose-urethane anesthesia. Pressor areas of the dorsal medulla (DM) and ventrolateral medulla (VLM) and the depressor area of the paramedian reticular nucleus (PRN) were stimulated electrically using a monopolar electrode, or chemically using sodium glutamate microinjection. Plasma levels of norepinephrine (NE) and epinephrine (EPI) were measured in caval blood above the adrenal veins. Electrical stimulation of the DM and VLM produced increases in blood pressure and in plasma NE and EPI levels that were enhanced after acute vagotomies. The NE and EPI responses were attenuated after acute, bilateral adrenalectomies, confirming augmented adrenomedullary secretion, whereas the pressor responses were intact. Injection of sodium glutamate into the same pressor regions of the DM or VLM also produced pressor responses and elevated plasma catecholamine levels, indicating that the responses resulted from activation of neuronal perikarya. Stimulation of the PRN attenuated pressor and catecholamine responses during stimulation of the DM and VLM. The results indicate that pressor responses during stimulation of the DM and VLM are due at least partly to activation of perikarya in these regions, are associated with but not dependent on adrenomedullary activation, and are enhanced after vagotomy; and that neurons of the PRN exert inhibitory modulation of the pressor and adrenomedullary responses during stimulation of VLM and DM.

Adrenal Glands↗
PubMed1991

Effect of region-of-interest in computerized densitometric analysis of radiographs.

The region-of-interest (ROI) in computer-assisted densitometric image analysis (CADIA) is defined by its size and location. This study evaluated the effects of these variables on two quantitative parameters, the change in density and the area with change in density. Pairs of radiographs for these analyses were obtained from sites with "no change" or "known loss" in Cynomolgus monkeys during a study of ligature-induced periodontitis. The size and location of the ROI had clear effects on the two CADIA parameters. To reduce these effects, a corrective procedure hypothesizing a linear relationship between the ROI size and the area with change in density was tested. While this procedure was sufficient to correct for ROI size-dependent differences among "no change" images, it was not effective in images with "known loss". In such images, additional adjustments by increasing threshold levels for the registered change in density were found to reduce but not to eliminate differences between ROIs of different size and location. When densitometric radiographic analysis is used for quantitative comparison of different sites, it is primarily recommended to select ROIs of similar size and location. Application of corrective procedures should follow only after careful evaluation of their effects on sensitivity and specificity.

Alveolar Bone Loss↗
PubMed1991

Role of selenium-dependent glutathione peroxidase in protecting against t-butyl hydroperoxide-induced damage in hepatocytes.

The role of the selenoenzyme glutathione peroxidase (Se-GSHPx) in protecting against oxidative injury was studied in hepatocytes isolated from rats fed either a low-selenium (Se-) or a selenium-adequate (Se+, control) diet. In rats fed Se- diet for eight weeks the selenium content of plasma and liver was lowered to 15 and 8%, respectively. No Se-GSHPx and only 5% of total GSHPx activity was detected in Se- hepatocytes. However, the Se- hepatocytes were as resistant as the Se+ cells to oxidative injury by 0.8 mM tert-butyl hydroperoxide (t-BuOOH), or 0.2 mM t-BuOOH plus 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), an inhibitor of oxidized glutathione (GSSG) reductase. Only at 1.5 mM t-BuOOH or at 0.5 mM t-BuOOH with BCNU were cell damage and lipid peroxidation more evident in Se- cells. At all t-BuOOH concentrations used the depletion of cellular glutathione (GSH) was similar in magnitude in Se- and Se+ cells, but Se+ cells released more glutathione (mainly GSSG), obviously due to their higher Se-GSHPx activity. These results suggest that hepatocytes devoid of Se-GSHPx activity maintain a high capacity to resist peroxidative attack, either via residual (non-Se)GSHPx activity or other compensatory GSH-associated detoxication mechanisms.

Animals↗
PubMed1991

Normal venous anatomy of the brain: demonstration with gadopentetate dimeglumine in enhanced 3-D MR angiography.

This investigation evaluates whether gadopentetate dimeglumine enhancement of three-dimensional (3-D) acquisition MR angiography can generate clinically useful images of the normal venous anatomy of the brain. 3-D MR angiography of normal cerebral arterial anatomy has made rapid progress, although demonstration of detailed venous anatomy with similar techniques has been much less revealing. To overcome the limitation of slow venous flow, IV gadopentetate dimeglumine contrast enhancement was used to alter the relaxation times of blood, thus augmenting the venous signal. Several groups of patients were evaluated: we studied eight patients both with and without contrast enhancement, 20 patients and volunteers with multiple techniques to determine optimal technical parameters, and seven patients in whom enhanced MR studies were compared with standard selective biplane cut-film arterial angiograms. Only the large dural sinuses (such as the transverse sinus) could be seen on unenhanced studies owing to the saturation of slowly flowing venous spins. With contrast enhancement, many of the important small and large cerebral venous structures were routinely seen with reasonable scanning times (7 min). The venous anatomy was well seen for approximately one-half hour after injection and correlated well with angiograms. There are several important limitations to this technique, including a limited field of view, variable visibility of specific veins owing to technical and physiologic factors, confusion of enhancing non-flow-related structures, and lack of detailed physiologic information. Single excitation 3-D MR angiograms are insensitive in the evaluation of cerebral venous structures. Enhancement with gadopentetate dimeglumine affords rapid scanning and excellent visualization of the pertinent venous anatomy. The best image quality was obtained with a sequence of 50/7/30 degrees (TR/TE/flip angle).

Adolescent↗
PubMed1991

[Determination of myristicin and safrol in the volatile oil of semen Myristicae and its processed products by TLC-scanning].

This paper reports the determination of myristicin and safrol in the volatile oil of Semen Myristicae and its processed products by TLC-Scanning. The results showed that in the processed products myristicin decreased markedly and safrol decreased slightly. The quantity of myristicin roasted with paste less than with wheat bran less than with talcum powder less than the unprocessed one. The toxicity of Semen Myristicae is related to the quantities of myristicin.

Allylbenzene Derivatives↗
PubMed1991

[Experimental anti-arrhythmic effects of zhigancao (prepared licorice) injection].

Zhigancao injection can antagonise the arrhythmia induced by chloroform, adrenaline, aconitine, strophanthine K and barium chloride, slow the heart rate, prolong P-R and Q-T intervals and antagonise the positive chronotropic response induced by isoprenaline. The LD50 of zhigancao injection is 41.2g/kg in nice by intraperitoneal.

Animals↗