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Biomedical subjects

Y Fu

Publications and source records attributed to Y Fu.

At least 307 records · Page 17Linked to original sources
PubMed1990

Evaluation of brain edema using magnetic resonance proton relaxation times.

Experimental and clinical studies on the evaluation of water content in cases of brain edema were performed in vivo, using MR proton relaxation times (longitudinal relaxation time, T1; transverse relaxation time, T2). Brain edema was produced in the white matter of cats by the direct infusion method. The correlations between proton relaxation times obtained from MR images and the water content of white matter were studied both in autoserum-infused cats and in saline-infused cats. The correlations between T1 as well as T2 and the water content in human vasogenic brain edema were also examined and compared with the data obtained from the serum group. T1 and T2 showed good correlations with the water content of white matter not only in the experimental animals but also in the clinical cases. The quality of the edema fluid did not influence relaxation time and T1 seemed to represent almost solely the water content of the tissue. T2, however, was affected by the nature of existence of water and was more sensitive than T1 in detecting extravasated edema fluid. It seems feasible therefore to evaluate the water content of brain edema on the basis of T1 values.

Animals↗
PubMed1989

Thymic involution and thymocyte phenotypic alterations induced by murine mammary adenocarcinomas.

A profound thymic atrophy has been observed in mice bearing large adenocarcinomas of the mammary gland. Only 2 to 5% of thymocytes remained 4 wk after tumor implantation. Although there is a slight decrease in the overall percentages of Thy-1+ cells in tumor bearers, the majority of the remaining cells are of a Thy-1 low phenotype. There was a lower percentage of double positive (CD4+, CD8+) cells, an increase of CD4+ CD8- thymocytes, similar percentages of CD4- CD8+ cells and double negative (CD4- CD8-) thymocytes in tumor-bearing mice. In addition, an increased percentage of CD3 cells could be detected in these animals. These results indicate that proportionally less immature thymocytes are present in the atrophic thymuses of mammary tumor bearers. Enhanced levels of glucocorticoids are known to produce similar effects on the thymus. However, adrenalectomy of mice followed by tumor implantation did not result in reversal of the thymic atrophy. Furthermore, a study of serum corticosterone levels in tumor bearers indicated no significant changes during tumorigenesis. A study of several parameters of bone marrow (BM) populations indicate that there is an increase in cells of the granulocyte-macrophage lineage and a decrease in lymphocytes induced by tumor-derived granulocyte macrophage-CSF. An alteration of prothymocytes in the BM is not the main cause of the thymic atrophy because BM cells from normal and tumor-bearing mice reconstituted irradiated normal mice equally well. There was no preferential recruitment of double positive cells to the spleen as indicated by no significant differences in the levels of T cells of immature phenotype including the CD4+ CD8+ population in the spleens of tumor bearers. Because no major changes were observed in tumor bearers, either at their capacity to repopulate the thymus or at the patterns of subsequent redistribution of thymocytes, it was postulated that the thymic atrophy may be caused by a direct or indirect effect of the tumor or tumor-associated factor(s). Intrathymic injections of tumor cells into young normal recipient mice resulted in a significant reduction of the thymus weight and cellularity. These data suggest that mammary tumors can secrete factor(s) that are capable of severely impairing the normal development of cells of the T cell lineage.

Adenocarcinoma↗
PubMed1989

A new microcatheter system for endovascular treatment of cerebral arteriovenous malformations.

A new microcatheter system was used for diagnostic and therapeutic purposes in three cases of arteriovenous malformation. This microcatheter is used with a steerable guidewire and provides high selectivity of the target vessels and greater catheter maneuverability than does balloon catheters. Tissue adhesive was safely injected for the therapeutic embolization in two of the cases. With this system, however, the utmost attention is necessary to prevent reflux of the tissue adhesive and to avoid lacerating the feeding vessels with the guidewire. This microcatheter system was found to be very useful for diagnostic and therapeutic procedures in endovascular treatment of cerebral arteriovenous malformations.

Adult↗
PubMed1989

Magnetic resonance imaging of intracavernous pathology.

To evaluate the usefulness of magnetic resonance (MR) imaging of intracavernous pathology, T1-weighted spin echo images of four vascular lesions and 10 neoplastic lesions with surgically confirmed cavernous sinus (CS) invasion were reviewed retrospectively. In one case of traumatic carotid-cavernous fistula (CCF) and one of dural arteriovenous malformation (AVM), the internal carotid artery (ICA) and rapid shunted flow were depicted as signal voids, and the relationship between the ICA and shunted flow was clearly shown. Normal venous flow appeared as a low-intensity area and was observed even in the presence of the CCF and dural AVM. In two cases of thrombosed aneurysms, the thrombosis was clearly demonstrated, along with patent arterial flow in one case; in the other case, however, it was impossible to differentiate patent arterial flow from calcification. The intensity of all neoplastic lesions was similar to that of the cerebral cortex. The relationship between the ICA and the tumors was clearly demonstrated. The visual pathways were also plainly shown unless they were involved, or markedly compressed, by tumor. CS invasion was strongly associated with four findings: 1) encasement of the ICA by the tumor; 2) marked displacement of the ICA; 3) absence of low intensity, which reflects normal venous flow, in the CS; and 4) extension of extrasellar tumors to the medial wall or of intrasellar tumors to the lateral wall. MR imaging was judged promising in the evaluation of intracavernous pathology.

Adenoma↗
PubMed1988

A possible maternal-effect mutant of Xenopus laevis: II. Studies of RNA synthesis in dissociated embryonic cells.

Embryos from a female of Xenopus laevis (designated as no. 65) arrest development at gastrulation and are assumed to be ova-deficient mutant. We dissociated these embryos and studied RNA synthesis at different stages. The cells from the ova-deficient embryos reaggregated quite actively as wild-type embryo cells until the late gastrula stage. RNA synthesis was normal at the early blastula stage but greatly inhibited by the late blastula (stage 9.5) stage, when the synthesis of DNA and protein was still not inhibited appreciably. Thus, inhibition in RNA synthesis appears to be the first manifestation of the maternal defect that occurs before the gastrulation arrest.

Animals↗
PubMed1988

[Surgical treatment of the second primary lung cancer].

1168 patients with primary carcinoma of lung had been treated by surgery in our hospital from 1976 to 1985. Among these patients we found 7 patients with second primary lung cancer. The incidence is 0.6% in this series. The criteria of the second primary lung cancer are: different histological type; synchronous lesion located in the contralateral lung or in different lobes or segments of the ipsilateral lung which must all be stage I; or prolonged interval between the initial and second resection (metachronous lesions), but the initial lesion must be proved as stage I. Lobectomy was the most common procedure for the initial and second resections. The result of the treatment was satisfactory with one patients surviving 6 years and 6 months. There was no operative mortality or complications. We consider that careful diagnosis is important and continued follow-up is necessary for all bronchogenic carcinomas.

Adenocarcinoma↗
PubMed1987

Acceleration of the rate of processing of 40 S pre-rRNA during Xenopus laevis embryogenesis.

Processing of 40 S pre-rRNA into 18 and 28 S mature rRNAs was studied in Xenopus embryonic cells by pulse-chase experiments using actinomycin D as a transcription-inhibitor. Gel electrophoretic analyses revealed that the rate of processing was accelerated due to a shortening of the half-life of 40 S pre-rRNA from 19 min at the gastrula stage to 9 min at and after the neurula stage. The step under developmental control appeared to be the cleavage of 40 S pre-rRNA into 18 S rRNA and the 34 S rRNA intermediate, since the time interval between the first detection of labeled 40 S pre-rRNA and 18 S rRNA was significantly shortened as development proceeded.

Animals↗
PubMed1987

Human papillomavirus type 16 in intraepithelial neoplasia (bowenoid papulosis) and coexistent invasive carcinoma of the vulva.

Tissues from two cases of bowenoid papulosis of the vulva with coexistent invasive squamous cell carcinoma were evaluated for the presence of human papillomaviruses (HPVs) and for nuclear DNA content. In both cases, HPV type 16 and nuclear aneuploidy were found in bowenoid papulosis as well as in invasive carcinoma. Patterns of hybridization suggested that the viral genome was integrated into the cellular genome in both bowenoid papulosis tissues as well as in invasive carcinoma tissues. These observations suggest that lesions designated as bowenoid papulosis may have invasive cancer potential. The term vulvar intraepithelial neoplasia seems to be more appropriate for HPV-16-containing aneuploid, intraepithelial lesions of the vulva.

Adult↗