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Biomedical subjects

C Yu

Publications and source records attributed to C Yu.

At least 199 records · Page 11Linked to original sources
PubMed1999

Carbon monoxide and cerebral microvascular tone in newborn pigs.

The present study addresses the hypothesis that CO produced from endogenous heme oxygenase (HO) can dilate newborn cerebral arterioles. HO-2 protein was highly expressed in large and small blood vessels, as well as parenchyma, of newborn pig cerebrum. Topically applied CO dose-dependently dilated piglet pial arterioles in vivo over the range 10(-11)-10(-9) M (maximal response). CO-induced cerebrovascular dilation was abolished by treatment with the Ca2+-activated K+ channel inhibitors tetraethylammonium chloride and iberiotoxin. The HO substrate heme-L-lysinate also produced tetraethylammonium-inhibitable, dose-dependent dilation from 5 x 10(-8) to 5 x 10(-7) M (maximal). The HO inhibitor chromium mesoporphyrin blocked dilation of pial arterioles in response to heme-L-lysinate. In addition to inhibiting dilation to heme-L-lysinate, chromium mesoporphyrin also blocked pial arteriolar dilations in response to hypoxia but did not alter responses to hypercapnia or isoproterenol. We conclude that CO dilates pial arterioles via activation of Ca2+-activated K+ channels and that endogenous HO-2 potentially can produce sufficient CO to produce the dilation.

Animals↗
PubMed1999

Contribution of endogenous carbon monoxide to regulation of diameter in resistance vessels.

Endogenous carbon monoxide was proposed to subserve vasodepressor functions. If so, inhibition of heme oxygenase may be expected to promote vascular contraction. This hypothesis was examined in large and small arteries and in isolated first-order gracilis muscle arterioles of rat. The heme oxygenase inhibitors chromium mesoporphyrin (CrMP) and cobalt protoporphyrin (0.175-102 micromol/l) decreased the diameter of pressurized (80 mmHg) gracilis muscle arterioles, whereas magnesium protoporphyrin, a weak heme oxygenase inhibitor, did not. CrMP also elicited development of isometric tension in the muscular branch of the femoral artery but not in the aorta or femoral artery. Arteriolar constrictor responses to CrMP varied in relation to the intravascular pressure, were blunted in preparations exposed to exogenous carbon monoxide (100 micromol/l), and were unaffected by an endothelin receptor antagonist. Importantly, CrMP amplified the constrictor response to increases of pressure in gracilis arterioles. Accordingly, the constrictor effect of heme oxygenase inhibitors is attributable to magnification of myogenic tone due to withdrawal of a vasodilatory mechanism mediated by endogenous carbon monoxide. The study suggests that the vascular carbon monoxide system plays a role in the regulation of basal tone in resistance vessels.

Animals↗
PubMed1999

Stereotactic radiosurgery in the treatment of metastatic disease to the brain.

We review 190 consecutive patients with 434 metastatic tumors treated by gamma knife stereotactic radiosurgery, from August 1994 to February 1999. Median actuarial survival for all patients was 34 weeks. Factors correlated with significantly improved survival included controlled systemic disease and nonmelanoma histology. We found that no significant survival benefit could be discerned from adjuvant whole brain radiotherapy in this patient group. Survival was not statistically different for patients initially presenting with 1-4 metastases at initial treatment.

Brain Neoplasms↗
PubMed1999

Hemodialysis-related nodulocystic acne treated with isotretinoin.

Some hemodialysis patients, without taking any acnegenic agents, developed severe nodulocystic acne with unknown causes. Because nodulocystic acne poorly responds to conventional acne therapy and increases the black pigmentation in the face, it severely interferes with the quality of life of these patients. To investigate whether isotretinoin is effective in treating hemodialysis patients with severe nodulocystic acne, we undertook a prospective, randomized, single-blind study. A total of 20 patients with nodulocystic acne participated in the study, of whom 18 completed it. Ten patients received isotretinoin 10 mg/day (5 mg/capsule) for 3 months as a study group and the other 10 took placebo for 3 months as a control group. The severity of acne and treatment-related side effects were evaluated monthly by a questionnaire and laboratory evaluation which included liver function tests, blood lipids and blood platelet counts. The results showed isotretinoin treatment significantly reduced the severity of acne of the study group patients after 1 month (scales of acne severity: 4.0 +/- 0.0 vs. 3.13 +/- 0.35, p < 0. 01) and 3 months (4.0 +/- 0.0 vs. 1.5 +/- 0.76, p < 0.01) of follow-up. In addition, the severity of acne of the study group patients was significantly less than that of the control group patients after 1 month (3.13 +/- 0.35 vs. 3.80 +/- 0.42, p < 0.01) and 3 months (1.5 +/- 0.76 vs. 3.70 +/- 0.48, p < 0.001) of treatment. Only mild side effects were noted. No significant changes of biochemical evaluation were found except that a mild elevation of aspartate aminotransferase was noted in the study group patients. However, two study group patients withdrew from the trial because of isotretinoin-related side effects and toxic hepatitis. In summary, our study first demonstrated that the small dose of isotretinoin effectively treated nodulocystic acne of hemodialysis patients and the side effects were mild. This result suggests that isotretinoin may be the treatment of choice for nodulocystic acne in end-stage renal disease patients with renal replacement therapy. The liver function and other isotretinoin-related side effects in these patients should be carefully monitored.

Acne Vulgaris↗
PubMed1999

TLD measurements of the relative output factors for the Leksell Gamma Knife.

The accuracy of the output factor directly affects the accuracy of dose delivery during patient treatment. At our Gamma Knife center, annual output factor measurements have been carried out by using a high accuracy TLD technique, characterized by the group annealing and sorting (GAS) procedure. For each collimator exposure, one to five LiF Thermoluminescent Dosimeter (TLD) 1 x 1 x 1 mm3 cubes were used, depending upon the collimator size, and the process was repeated until approximately 10 TLDs had been exposed for each collimator. Transit radiation dose accumulated during the motion of the treatment couch was measured for each collimator helmet, and the result was subtracted from the uncorrected TLD dose measurements. The mean values of the output factors for the 14, 8 and 4 mm collimators from last 5 years were 0.985 ¿ 0.001, 0.948 ¿ 0.005 and 0.833 ¿ 0.007, respectively, relative to the 18 mm collimator. These measured relative output factors are virtually identical to the values recommended by the manufacturer for the 14 mm and 8 mm collimators. On the other hand, the output factor for the 4 mm collimator was approximately 4.1% larger than that recommended by the manufacturer. The significance of these findings is discussed.

Radiosurgery↗
PubMed1999

Alternative and effective treatment of shoulder ganglion cyst: ultrasonographically guided aspiration.

The therapeutic effect of ultrasonographically guided aspiration of a ganglion cyst of the shoulder is evaluated. Fifteen patients (nine male, six female) with chronic shoulder pain were enrolled in this study. Each patient was referred to rule out rotator cuff lesion. The ultrasonographic examination showed an anechoic cystic lesion in the shoulder region in every patient and abnormality of the rotator cuff in only four patients. Under ultrasonographic guidance, an 18 gauge needle was inserted into the cyst to aspirate the fluid. Initial sonographic imaging showed the cyst, which appeared as a localized fluid accumulation and was located between the deltoid muscle and the subscapularis tendon in seven patients, between the deltoid muscle and the biceps tendon in one patient, below the coracoacromial ligament in five patients, and over suprascapular notch area in one patient. The ganglion cysts ranged in size from 3.5 to 30 mm. The amount of aspirated fluid in each cyst varied from 0.4 to 12 ml (mean, 2.6 ml +/- 3.1) with a clear or light yellowish color and a jelly-like appearance. No major complications occurred during or after this procedure. The symptom (pain) was improved after sonographically guided aspiration in each patient. Follow-up study showed complete relief of pain in four patients, marked improvement in nine patients, and mild improvement but still persistent shoulder pain in two patients. Duration of follow-up study ranged from 2 to 24 months (mean, 6.4 months +/- 6.9). The success rate for sonographically guided aspiration was 86% on the basis of marked symptom improvement or relief. Ultrasonographically guided aspiration of shoulder ganglion cysts is an effective procedure in the management of shoulder pain caused by ganglion cysts.

Adult↗
PubMed1999

[Selection of human phage antibodies against HAV and DNA sequence analysis].

OBJECTIVE: To obtain the anti-HAV antibodies. METHODS: The antibody-capturing antigen strategy was used in panning antibody library with impure antigen. The HAV-binding activity and specificity of phage antibodies were assayed by sandwich ELISA and competitive inhibition ELISA. RESULTS: Phage antibodies(Fab) against HAV were screened from a human immunoglobulin combinatorial library. Fd and light chain genes were sequenced. Comparison of the Fd gene and light chain gene with KABAT database showed that the heavy chain belonged to IgG1 subclass, and its variable region was derived from rearranged germ-line gene of DP88, D3-3 and JH5; while the light chain was a member of V kappa III family, the germ-line gene was DP kappa 22 and J kappa 4. CONCLUSION: Phage antibodies against HAV were selected from the antibody library by using the antibody-capturing antigen strategy. The result also suggested that the antibody library was constructed successfully.

Amino Acid Sequence↗
PubMed1999

[Transcranial approach to the orbit: a microanatomical study].

OBJECTIVE: To provide detailed knowledge of microanatomy and parameters for transcranial approach to the orbit. METHOD: Three intraorbital approaches were studied by dissecting and measuring 20 adult cadaveric heads under x5 to 25 magnification. RESULTS: The medical approach was directed through the space between the superior oblique and the levator palpebrae superior muscles, which was selected for lesions located in the medial part of the orbital apex. The central approch was directed through the space between the levator palpebrae superior and the superior rectus muscles. There were two variants of the central approach, the choice of which depends on whether the frontal nerve was retracted medially or laterally. The approach was selected for lesions located in the midportion of the intraorbital segment of the optic nerve. The lateral approach was directed through the space between the superior and the lateral rectus muscle. There were two variants of the lateral approach, the choice of which was determined by whether the superior ophthalmic vein is retracted medially or laterally. This approach was selected for lesions located in the superior, inferior or lateral part of the orbital apex as well as the superior orbital fissure. CONCLUSION: This research provides a microanatomical foundation for avioding the important nerves and vessels damage in transcranial to orbital surgery.

Adult↗
PubMed1999

[The effect of hysterectomy on sexual behavior in women].

OBJECTIVES: To explore the effect of total hysterectomy on sexual behavior in women and to improve the quality of life in posthysterectomic women. METHODS: We observed 107 of patients who had received surgery for more than six months. They were divided into 3 groups: 1st group (19 pationts), hysterectomy; 2nd group (18), unilateral salpingo-oophorectomy and hysterectomy; and 3rd group (70), bilateral salpingo-oophorectomy and hysterectomy. The patients were also divided into groups(< 45 years, 45-50 years, > 50 years) according to age. The difference of sexual behavior before and after hysterectomy was compared and the effect of FSH, E2, T on sexual behavior was also analysed. RESULTS: Sexual function after hysterectomy was normal in 43.9%, sexual disturbance 26.2%, fear or misunderstanding 17.8%, and no partner or ill partner 12.2%. Sexual function and sexual desire in the < 45 years group was significantly different from other groups (chi 2 = 11.2633, P = 0.0036). The effect of E2 on sexual function and desire was significant (t = 2.18, P = 0.032). CONCLUSIONS: Total hysterectomy affects sexual behavior. It is highly important to advise patients to get rid of psychosomatic disturbances before and after hysterectomy. Since overian function is very important for maintenance of normal sexual function, it is not advisable to do preventive overiotomy. The estrogen level has a great influence on the sexual behavior of women who had hysterectomy, but the role of androgen in women's sexual behavior needs to be studied.

Adult↗
PubMed1999

[The effect of alginate purity on microencapsule overgrowth and function of microencapsulated hepatocyte in peritoneal transplantation].

OBJECTIVE: To study the effect of alginate purity on microencapsule overgrowth, histology and function of microencapsulated hepatocyte (MH). METHODS: Alginate was purified by filtration and chloroform/butanol extraction. Using purified and crude alginate to make two kinds of MHs, we transplanted each kind of MHs into the peritoneal cavities of rats. After 2 weeks, 1, 2 and 6 months, MHs were washed out to study overgrowth of MH, histology, and expression of enzyme and albumin in hepatocytes. Two kinds of MHs (the purified and the crude) were transplanted to FHF rats separately to study their differences in liver function support. RESULTS: The amount of retrieved MHs was larger in the purified than in the crude (P < 0.001). In the purified group, most hepatocytes had normal morphology, positive enzymatic histochemistry and albumin immuno-histochemistry stain in one month of transplantation but were damaged in the crude group only 2 weeks later. Microencapsules were smooth and no overgrowth was observed during 6 months in the purified but all overgrowth one month later after transplantation in the crude. The purified MHs had excellent liver function support in the FHF comparing with the crude and the control. CONCLUSION: The purified alginate may significantly reduce the overgrowth of MHs and improve the function of hepatocytes.

Alginates↗
PubMed1999

[Lateral approaches for treatment of petroclival region tumor].

OBJECTIVE: To summarize the operation experience of resecting petroclival region tumors by lateral approaches. METHODS: (1) Ameliorate pterion approach; (2) temporal-occipital transtentorial-transpetrous approach; (3) transpetrous combined with supratentorial and infratentorial presigmoid approach; (4) far lateral transcondylar approach were applied for 61 patients with petroclival region tumor. RESULTS: Of the 61 tumors studied, 54 were completely resected, 6 were nearly complete and 1 was subtotally resected. No patient died in this group, 37 patients were followed up, and all showed satisfying results. 45% of the patients had CNs deficit, with III, VI, V, VIII, IX, X, XII nerve deficits most commonly seen. CONCLUSION: Lateral approaches are recommended for total resection of petroclival region tumors. HoVDever the operative techniques are complex and potential risks of morbidity exist.

Adolescent↗
PubMed1999

[Transpetrosal presigmoid approach for removal of giant petroclival tumors].

OBJECTIVE: To discuss the operative technique, advantage and postoperative complications in 41 patients with giant petroclival tumors treated with the supra- and infratentorial transpetrousal presigmoid approach. METHODS: Clinical data were obtained from the review of charts and radiographic images of the 41 patients after operation with temporo-occipotal free osseous flap, partial petrosectomy and mastoidectomy were performed around the labyrinth. The semicircular canals, cochlea and tympanic cavity were protected during the operation. After the super petrous was ligated and cut off, the petroclival region in front of the sigmoid sinus was exposed. RESULTS: In the 41 patients 20 had meningiomas, 20 epidermoid cysts, and one schwannoma. Total resection was performed in 34 patients, subtotal resection in 16, and greater partial resection in one. Major postoperative complications included temporal aphasia (10 patients), cerebral edema (6), brain stem infarct (2), IIIth, VIIth, VIth and posterial group cranial nerves palsies (16, 16, 8, 6 respectively), and cerebrospinal fluid leakage (4 cases). CONCLUSIONS: This approach can expose sufficiently the petroclival region. It can also reveal the area of adjacent sella, interpeduncular and formen magnum, and homolateral III-XIIth cranial nerves. The postoperative complications may be related to operative techniues and tumorous characteristics.

Adolescent↗
PubMed1999

[TNF-alpha, IL-8 and IL-6 in the early inflammatory stage of experimental PVR model induced by macrophages].

OBJECTIVE: To observe the levels of cytokines, tumor necrosis factor-alpha (TNF-alpha), interleukin-8 (IL-8) and IL-6 in the early inflammatory stages of a rabbit proliferative vitreoretinopathy (PVR) model induced by macrophages. METHODS: The vitreous and venous blood of rabbit eyes of the PVR model were obtained and tested with ELISA kits of TNF-alpha, IL-8 and IL-6 and analyzed statistically. RESULTS: The TNF-alpha level increased at the 7th day after macrophage injection and reached its peak (309 pg/ml) on day 21. IL-8 and IL-6 maintained their higher levels during 7 to 21 days after macrophage injection and the peak levels were 1 325 pg/ml and 998 pg/ml on day 14 respectively. Those showed significant differences compared to control (P <or= 0.05). CONCLUSION: The 3 cytokines, TNF-alpha, IL-8 and IL-6, present high levels in the early stage and proliferative phase of the PVR model and decrease to normal level in the regeneration (scarring) phase, indicating that these cytokines may play an important role in initiating and modulating the cellular proliferation.

Animals↗
PubMed1999

[Determination of active components in caoyiguang wettable powder by reversed-phase high performance liquid chromatography].

The Caoyiguang wettable powder is composed of two active components, synergists and other additives. The active components, bensulfuron methyl (Londax) and metolachlor (Dual), in 15.5% Caoyiguang wettable powder were determined by reversed phase high performance liquid chromatographic method simultaneously. The ZORBAX SB-C18 column (4.6 mm i.d. x 250 mm, 5 microns) and acidic mixture of methanol and water as mobile phase were used. The results showed that the recoveries were 98.1%-102.6%, and the coefficients of variation were 0.4%-0.8%. The method has been used to determine samples with satisfactory results.

English Abstract↗
PubMed1998

Analysis of the role of variation of major histocompatibility complex class II expression on nonobese diabetic (NOD) peripheral T cell response.

The current paradigm of major histocompatibility complex (MHC) and disease association suggests that efficient binding of autoantigens by disease-associated MHC molecules leads to a T cell-mediated immune response and resultant autoimmune sequelae. The data presented below offer a different model for this association of MHC with autoimmune diabetes. We used several mouse lines expressing different levels of I-Ag7 and I-Ak on the nonobese diabetic (NOD) background to evaluate the role of MHC class II in the previously described NOD T cell autoproliferation. The ratio of I-Ag7 to I-Ak expression correlated with the peripheral T cell autoproliferative phenotype in the mice studied. T cells from the NOD, [NOD x NOD. I-Anull]F1, and NOD I-Ak transgenic mice demonstrated autoproliferative responses (after priming with self-peptides), whereas the NOD.H2(h4) (containing I-Ak) congenic and [NOD x NOD. H2(h4) congenic]F1 mice did not. Analysis of CD4(+) NOD I-Ak transgenic primed lymph node cells showed that autoreactive CD4(+) T cells in the NOD I-Ak transgenic mice were restricted exclusively by I-Ag7. Considered in the context of the avidity theory of T cell activation and selection, the reported poor peptide binding capacity of NOD I-Ag7 suggested a new hypothesis to explain the effects of MHC class II expression on the peripheral autoimmune repertoire in NOD mice. This new explanation suggests that the association of MHC with diabetes results from "altered" thymic selection in which high affinity self-reactive (potentially autoreactive) T cells escape negative selection. This model offers an explanation for the requirement of homozygous MHC class II expression in NOD mice (and in humans) in susceptibility to insulin-dependent diabetes mellitus.

Animals↗
PubMed1998

Evidence for circulating bone marrow-derived endothelial cells.

It has been proposed that hematopoietic and endothelial cells are derived from a common cell, the hemangioblast. In this study, we demonstrate that a subset of CD34(+) cells have the capacity to differentiate into endothelial cells in vitro in the presence of basic fibroblast growth factor, insulin-like growth factor-1, and vascular endothelial growth factor. These differentiated endothelial cells are CD34(+), stain for von Willebrand factor (vWF), and incorporate acetylated low-density lipoprotein (LDL). This suggests the possible existence of a bone marrow-derived precursor endothelial cell. To demonstrate this phenomenon in vivo, we used a canine bone marrow transplantation model, in which the marrow cells from the donor and recipient are genetically distinct. Between 6 to 8 months after transplantation, a Dacron graft, made impervious to prevent capillary ingrowth from the surrounding perigraft tissue, was implanted in the descending thoracic aorta. After 12 weeks, the graft was retrieved, and cells with endothelial morphology were identified by silver nitrate staining. Using the di(CA)n and tetranucleotide (GAAA)n repeat polymorphisms to distinguish between the donor and recipient DNA, we observed that only donor alleles were detected in DNA from positively stained cells on the impervious Dacron graft. These results strongly suggest that a subset of CD34+ cells localized in the bone marrow can be mobilized to the peripheral circulation and can colonize endothelial flow surfaces of vascular prostheses.

Animals↗