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Biomedical subjects

Y Fu

Publications and source records attributed to Y Fu.

At least 253 records · Page 14Linked to original sources
PubMed1993

[MR findings in traumatic cerebrospinal fluid leakage with special reference to indications of the need for dural repair].

Eleven cases of traumatic cerebrospinal fluid (CSF) leakage (8 cases of rhinorrhea and 3 cases of otorrhea) were reviewed to discuss magnetic resonance (MR) findings and surgical indications of the need for dural repair. Five patients had delayed onset of CSF rhinorrhea, 12 to 66 days (mean 28 days) after the trauma, and in the remaining 6 patients (3 rhinorrhea and 3 otorrhea) CSF leakage was noted on admission. MR study was carried out within 7 days after the onset of CSF leakage using a 0.5 tesla imager. In 7 cases of rhinorrhea, MR images demonstrated brain herniation into the ethmoid or frontal sinuses and the dural defects were repaired with the vascularized periosteum flap taken from the frontal bone or the fascia lata. In the operations, brain parenchyma was found to be plugged into the fracture line as MR images showed, and also to adhere to the margin of dural fistula. In the remaining 4 patients (without the MR findings of brain herniation into the paranasal sinuses) spontaneous cessation of CSF leakage occurred and their clinical course was good. Spontaneous cessation of CSF leakage in these cases may suggest the complete healing of the lacerated dura. However, in cases with the brain herniated into the paranasal sinuses CSF leakage may not be observed, and natural healing of the dural defect cannot be expected. Therefore, such brain herniation indicates the absolute need for dural repair even if CSF leakage is not observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Carboxy-terminal-extended variant of the human fibrinogen alpha subunit: a novel exon conferring marked homology to beta and gamma subunits.

Similarities between the N-terminal regions of the three subunits of the clotting protein fibrinogen--(alpha beta gamma)2--suggest that they evolved from a common progenitor. However, to date no human alpha chain has been found with the strong C-terminal homology shared by the beta and gamma chains. Here we examine the natural product of a novel fibrinogen alpha chain transcript bearing a separate open reading frame that supplies the missing C-terminal homology to the other chains. Additional splicing leads to the use of this extra sequence as a sixth exon elongating the alpha chain by 35%. Since the extended alpha chain (alpha E) is assembled into fibrinogen molecules and its synthesis is enhanced by interleukin-6, it suggests participation in both the acute phase response and normal physiology.

Amino Acid Sequence↗
PubMed1992

Nitric oxide-induced anti-mitogenic effects in high and low responder rat strains.

Nitric oxide (NO) has multiple biologic functions: in the brain it acts as a neuronal messenger; elsewhere, it causes smooth muscle relaxation, inhibition of platelet aggregation, inhibition of leukocyte adhesion, inhibition of tumor growth, and microbiostasis. Our studies show that production of NO is responsible for the unusual unresponsiveness of BN rat spleen cells to mitogens. NG-monomethyl-L-arginine (NGMMA), a potent competitive inhibitor for NO synthase, reverses this defect. Lysed RBC or NGMMA were shown to enhance mitogen-induced spleen cell proliferation only one- to twofold in Lewis rats (that have normal mitogen responsiveness) but act to stimulate BN rat T cells by 10- to 100-fold. NGMMA-enhanced proliferation was significantly diminished by prior depletion of macrophages. Surprisingly, NO did not inhibit IL-2 production in 48-h cultures of BN rat spleen cells, and exogenous IL-2 was ineffective in releasing NO-mediated suppression. These studies indicate that NO produced by macrophages can completely and reversibly inhibit T cell proliferation. The BN rat appears to be unique in its production of very high levels of NO, making it an especially useful animal model for studying the biologic control and functional consequences of NO generation.

Animals↗
PubMed1992

Immunohistochemical localization of progesterone receptor in human decidua of early pregnancy.

Rat monoclonal antibodies to human progesterone receptor were used for immunolocalization studies in human decidua of early pregnancy. Frozen sections of 42 specimens of decidua were stained by the peroxidase-antiperoxidase method (PAP). Progesterone receptor was localized exclusively in the nuclei of decidual and myometrial cells with no specific staining in the cytoplasm. In the decidualized endometrium, stroma were always positively stained. Smooth muscle, pericyte and endothelial cells of blood vessels were extensively stained. Glandular epithelia showed variation in staining, which was positive in the basal but very weak or negative in the superficial layer of the decidua. No specific staining could be detected in the control sections. Of special interest was the positive staining of the endothelium of decidual blood vessels, a finding which has not been reported previously. The cells of the inner lining of vessels that stained with the antiprogesterone receptor antibodies were also Factor VIII positive, thus confirming the endothelial nature of these cells. It is concluded from these results that endothelial cells from human first trimester decidua express progesterone receptors.

Adult↗
PubMed1992

Early changes of affinity and binding sites of progesterone and oestrogen receptors in decidua exposed to RU 486.

Sixty patients with 6-7 weeks of amenorrhoea were randomly allocated to three groups. The women in the first group (control) took a placebo 24 h before undergoing a vacuum aspiration. The patients in the second and third groups were given 200 mg of RU 486 orally, 12 or 24 h before surgical interruption of their pregnancy. Decidua were collected and frozen in liquid nitrogen. By Scatchard plot analysis, the number of cytosolic binding sites (1798 +/- 803 fmol/mg DNA) of progesterone in decidua in the control group was significantly reduced (P less than 0.01) to 696 +/- 408 or 626 +/- 179 fmol/mg DNA by RU 486 treatment for 12 or 24 h respectively. The dissociation constants of both cytosolic and nuclear progesterone receptors in RU 486-exposed decidua were increased (P less than 0.01). The number of nuclear binding sites of oestrogen receptor was significantly higher (P less than 0.05) in decidua with RU 486 treatment for 12 h (178 +/- 77 fmol/mg DNA) compared to the control (89 +/- 32 fmol/mg DNA). The results suggest that RU 486 might regulate progesterone and oestrogen receptors in the decidua of early human pregnancy, either directly or indirectly.

Binding Sites↗
PubMed1992

Modulation of interactions of Candida albicans and endothelial cells by fluconazole and amphotericin B.

Using an in vitro model of intravascular infection, we examined the effects of exposure to subinhibitory concentrations of fluconazole and amphotericin B on the ability of Candida albicans to adhere to and damage human umbilical vein endothelial cells. Incubation of the organisms for 18 h in 0.5x the MICs of fluconazole and amphotericin B inhibited endothelial cell adherence by 22 and 91%, respectively (P less than 0.001 for each drug). Candida-induced endothelial cell injury was also decreased by exposing the organisms to the antifungal drugs while in contact with the endothelial cells. Fluconazole inhibited damage by approximately 50% at concentrations ranging from 0.25x to 5x the MIC (P less than 0.01 for each concentration). Exposure to amphotericin B at 0.5x the MIC completely blocked the ability of the organisms to injure endothelial cells. The capacities of the antifungal agents to inhibit endothelial cell injury paralleled their abilities to suppress candidal germination. Organisms exposed to up to 5x the MIC of fluconazole had diminished, but still detectable, germ tube production and elongation, whereas incubation in 0.5x the MIC of amphotericin B completely abrogated germination. In addition to their direct effects on the growth of C. albicans, fluconazole and amphotericin B may decrease the ability of the fungus to disseminate hematogenously by inhibiting the organisms' capacity to adhere to and injure endothelial cells.

Amphotericin B↗
PubMed1992

A synthetic glycoconjugate representing the genus-specific epitope of chlamydial lipopolysaccharide exhibits the same specificity as its natural counterpart.

The tetrasaccharide 3-deoxy-alpha-D-manno-2-octulosonic acid (alpha-KDO) (2----8)-alpha-KDO(2----4)-alpha-KDO(2----6)-beta GlcNAc, a partial structure of chlamydial lipopolysaccharide (LPS) representing a genus-specific epitope, was synthesized and covalently linked to bovine serum albumin, resulting in an artificial glycoconjugate antigen. Mice were immunized with the glycoconjugate to prepare chlamydia-specific monoclonal antibodies. They were selected with chlamydia-specific LPS antigens and the structurally and antigenically related Re-type LPS of a Salmonella minnesota rough mutant. Characterization of the selected antibodies was by (i) hemagglutination of sheep erythrocytes coated with recombinant chlamydia-specific LPS, (ii) inhibition by synthetic polyacrylamide derivatives containing the genus-specific epitope or partial structures thereof, (iii) enzyme immunoassay with recombinant LPS and synthetic bovine serum albumin glycoconjugates as solid-phase antigens, (iv) immunofluorescence of L929 monolayers infected with Chlamydia psittaci or C. trachomatis, and (v) Western immunoblots with glycoconjugates and LPS as the antigen. Two groups of monoclonal antibodies were obtained; the monoclonal antibodies in one group cross-reacted with chlamydial and Re-type LPS, but those of the other group were chlamydia specific. Among the latter, KDO trisaccharide-specific antibodies that had the same epitope specificity as antibodies obtained after immunization with chlamydial elementary bodies were identified; however, they exhibited a more than 100-fold higher affinity. In addition, antibodies that bound preferentially to the 2.8-linked KDO disaccharide were detected, although with lower affinity. The data show that the artificial glycoconjugate antigen is similar to its natural counterpart.

Animals↗
PubMed1992

Susceptibility testing of Cryptococcus neoformans: a microdilution technique.

We studied a series of test conditions in a microtiter system to define the optimal method for determining the susceptibility of Cryptococcus neoformans to antifungal agents. Twenty-one isolates of C. neoformans were grown for 24 or 48 h in four chemically defined media: yeast nitrogen base (BYNB 7); RPMI 1640; synthetic amino acid medium--fungal (SAAMF), buffered at pH 7.0 to select the medium that best supported growth of this fastidious yeast; and yeast nitrogen base, pH 5.4 (YNB 5.4). Maximum growth of C. neoformans, at 35 degrees C, was obtained in YNB 5.4, with the next highest growth levels in BYNB 7, SAAMF, and RPMI. Growth at 24 h was uniformly poor in all media and lacked reproducibility. In contrast, incubation for 48 h gave adequate growth with low standard deviations, and 48 h was selected as the optimal incubation period for this study. Comparison of the relationship between growth kinetics and initial inoculum size for eight cryptococcal isolates showed that 10(4) cells per ml yielded optimal growth in BYNB 7 and YNB 5.4, whereas 10(5) cells per ml was optimal in RPMI and SAAMF. Furthermore, variation of inocula from 10(3) to 10(5) cells per ml showed small but significant inoculum effects in determining MICs of fluconazole, amphotericin B, and flucytosine for C. neoformans. Therefore, 10(4) cells per ml was chosen as the optimal inoculum for susceptibility testing in this study. Mean MICs of fluconazole, amphotericin B, and flucytosine for 21 crytococcal isolates in RPMI and BYNB 7 were low (for example, fluconazole had mean MICs of 1.2 and 1.3 micrograms/ml in RPMI and BYNB 7, respectively) and differed significantly from medium to medium. In contrast, the MICs obtained in SAAMF were significantly higher (e.g., fluconazole had a mean MIC of 2.2 micrograms/ml). Variance in MICs was large with fluconazole and flucytosine but small with amphotericin B, irrespective of the medium used. A microtiter system employing BYNB 7 as the medium, 48 h as the incubation period, and 10(4) cells per ml as the final inoculum is a simple, accurate, and reproducible method for the testing of C. neoformans susceptibility to fluconazole, amphotericin B, and flucytosine.

AIDS-Related Opportunistic Infections↗
PubMed1992

Significance of gadolinium-enhanced magnetic resonance imaging in differentiating spinal cord radiation myelopathy from tumor. Case report.

A young woman with a fourth ventricular ependymoma underwent radiotherapy following tumor excision. Twenty months later she developed a progressive neurological deficit at the C-2 vertebral level. Gadolinium-enhanced magnetic resonance imaging, showed an intramedullary lesion at the C-2 level. Although radiation myelopathy was suspected, tumor recurrence could not be excluded. Re-exploration and histopathology both confirmed a diagnosis of radiation myelopathy. A retrospective review of the case indicated findings favoring radiation myelopathy. The pertinent literature is reviewed and the findings discussed.

Adult↗
PubMed1992

[Ischemic complications following parent artery occlusion with detachable balloons in the treatment of large carotid aneurysms: effectiveness of 99mTc-HMPAO SPECT and importance of postoperative management].

Three patients with large carotid aneurysms were treated by parent artery occlusion with detachable balloons. Of these, 2 had intracavernous carotid artery aneurysms and one had a carotid-ophthalmic aneurysm. All patients underwent a formal balloon occlusion test and tolerated it well. One patient with a carotid-ophthalmic aneurysm, however, developed postoperative ischemic effects. This case was that of a 55 year-old female with right visual disturbance. Her middle cerebral artery flow had been compromised during test occlusion under induced hypotension. Although initially intact after balloon occlusion, she was found to be hemiplegic 24 hours later. She subsequently developed multiple small infarcts which were shown on MRI and which corresponded exactly to the previously demonstrated region of decreased flow during testing. This ischemic complication is possibly due to hypoperfusion, but embolism from the thrombosed aneurysm can not be denied. To prevent these complications, an extracranial-intracranial artery anastomosis prior to parent artery occlusion should be considered if the preoperative 99mTc-HMPAO SPECT shows a compromised cerebral blood flow. In addition to this, postoperative anticoagulant therapy should be given even if test occlusion was well tolerated clinically.

Brain Ischemia↗
PubMed1992

[Therapeutic occlusion of unilateral vertebral artery for unclippable aneurysms; special reference to postoperative brainstem ischemia].

Seven cases of unclippable vertebral artery aneurysms (3 dissecting, 1 fusiform, 2 saccular and 1 giant) are reported. Five of these had subarachnoid hemorrhage, one showed mass effect and the other was found incidentally. Trapping of the involved portion of the vertebral artery was performed in 4 cases, proximal clip occlusion in 2 and proximal balloon occlusion in 1. There were no operative deaths and no rebleeding, but brainstem ischemia developed in 4 cases, two being transient and two permanent. The ischemic complications were possibly due to; (a) hypoperfusion in the transient cases and (b) thromboenbolism, from the partially thrombosed giant aneurysm or thrombosis of the cul-de-sac vertebral artery, in the permanent ones. Preoperative temporary vertebral artery occlusion with an inflatable balloon or postoperative anticoagulant therapy should be considered in the management protocol.

Aortic Dissection↗
PubMed1992

[Management of elderly patients with aneurysmal subarachnoid hemorrhage].

Clinical features of 61 elderly patients aged over 70 years with ruptured intracranial aneurysms were compared with those of 328 younger patients aged under 70 years. According to a policy of early operation, elderly patients with Hunt and Kosnik's grade I, II and younger patients with grade I, II, III were operated on in the acute stage. In elderly patients with grade III, IV and younger patients with grade IV, the indication for surgery was determined case by case. Surgery was performed on 29 patients (48%) in the elderly group and 277 patients (86%) in the younger group. Our conclusions are as follows: 1. Regarding cases of grade I, II and III of Hunt and Kosnik's classification, the rate of good outcome in the elderly group was similar to that in the younger group, following early surgery and meticulous post-operative care. 2. In the elderly group, no patient in cases of grade IV obtained good surgical outcome. 3. Symptomatic vasospasm was less frequent in elderly patients (18.8%) than in younger cases (37%). 4. Delayed operation was planned for some patients in the elderly group, but none of them underwent surgery because of rerupture of aneurysms and deterioration of general condition.

Adult↗