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Biomedical subjects

Y C Wang

Publications and source records attributed to Y C Wang.

At least 127 records · Page 7Linked to original sources
PubMed1996

Comparison of the rate of excision of major UV photoproducts in the strands of the human HPRT gene of normal and xeroderma pigmentosum variant cells.

Xeroderma pigmentosum (XP) variant patients are genetically predisposed to sunlight-induced skin cancer. Fibroblasts from such patients are extremely sensitive to mutations induced by UV radiation, and the spectrum of mutations induced in their hypoxanthine phosphoribosyltransferase (HPRT) gene differs significantly from that seen in normal cells. To determine if this UV hypermutability reflects abnormally slow excision repair of cyclobutane pyrimidine dimers (CPD) or 6-4 pyrimidine-pyrimidones (6-4s) in that gene, we synchronized XP variant and normal fibroblasts, irradiated them in early G1-phase, 12 or more hours prior to the scheduled onset of S phase, harvested them immediately or after allowing various times for repair, and analyzed the DNA for photoproducts in the HPRT gene, using quantitative Southern blotting. To incise the DNA at CPD, we used T4 endonuclease V; to incise at 6-4s, we first used photolyase and UV365nm to reverse CPD and then UvrABC excinuclease. Excision of CPD was rapid, preferential, and strand-specific, but there was no significant difference in rate between the two kinds of cells. The half life was 4 h in the transcribed strand of the gene and 6.5 h in the nontranscribed strand. For excision of CPD in the genome overall, this value is 12 h. Excision of 6-4s from either strand of the HPRT gene was extremely rapid and preferential in both kinds of cells, with a half life of approximately 30 min. The results indicate that the UV hypermutability of the XP variant cells cannot be caused by slower rates of repair of CPD and/or 6-4s in the target gene for mutagenesis.

Blotting, Southern↗
PubMed1996

Induction of autologous tumor-specific cytotoxic T-lymphocyte activity against a human renal carcinoma cell line by B7-1 (CD8O) costimulation.

Recently mouse models have shown that expression of costimulatory molecules such as B7-1 on tumor cells can induce tumor-specific immunity, suggesting that tumor cells modified to express costimulatory molecules can be a potential tumor vaccine. To investigate the importance of B7-1 co-stimulation in induction of autologous tumor immunity in humans, we established a renal carcinoma cell line, RCC-1, from a tumor resection and studied the patient's antitumor immune responses in vitro. The RCC-1 cell line constitutively expressed major histocompatibility complex (MHC) class I, intercellular adhesion molecule (ICAM)-1, and leukocyte function-associated antigen (LFA)-3 molecules, and MHC class II molecules were induced by interferon-gamma (IFN-gamma) treatment in vitro. However, neither RCC-1- nor IFN-gamma-treated RCC-1 cells expressed B7-1, and both failed to induce T-cell proliferative responses in mixed lymphocyte and tumor cell reaction (MLTR) assays, suggesting that the costimulatory signals provided by cell adhesion molecules such as ICAM-1 and LFA-3 were not sufficient to elicit an antitumor immune response. However, on transfection of the human B7-1 into RCC-1, these cells were able to induce a significant T-cell proliferation in MLTR assays. This T-cell response could be blocked by anti-B7 mAb treatment of the tumor cells. RCC-1B7 cells also induced the generation of tumor-specific cytolytic T lymphocytes to the parent RCC-1 cells in vitro, with little nonspecific cytolysis of an unrelated RCC line, A498, or autologous phytohemagglutinin (PHA) blasts. This specific cytotoxicity could be abrogated by anti-CD8 mAb and complement treatment. In summary, our study indicates that B7-1-CD28 interaction plays a critical role in induction of autologous tumor-specific cytotoxic T lymphocytes (CTLs) in humans, suggesting that the costimulatory molecule transfected tumor cells could be useful in expanding tumor-specific autologous CTL in vitro for adoptive tumor immunotherapy.

Antigens, Neoplasm↗
PubMed1996

Tarsometatarsal joint: anatomic details on MR images.

PURPOSE: To evaluate the diagnostic capabilities of magnetic resonance (MR) imaging in the tarsometatarsal ([TMT] Lisfranc) joint with close anatomic correlation. MATERIALS AND METHODS: Six normal cadaveric feet were imaged by using T1-weighted spin-echo (oblique axial) and three-dimensional spoiled gradient-recalled acquisition in the steady state ([SPGR] coronal, sagittal) sequences. Subsequently, gadolinium-enhanced arthrography was performed in three specimens followed by T1-weighted spin-echo and SPGR MR imaging. Specimens were sectioned in all three planes followed by correlation of the MR imaging results with gross anatomic findings. RESULTS: In all specimens, the oblique axial and, less effectively, the coronal and sagittal planes allowed visualization of the Lisfranc ligament. Intermetatarsal ligaments were seen almost exclusively on the coronal images, and TMT ligaments on the sagittal images. Bone alignment could be assessed on the oblique axial images. CONCLUSION: MR imaging reliably depicts the anatomy of the TMT joint including ligamentous and osseous structures.

Cadaver↗
PubMed1996

Alteration of cerebral microcirculation by hemodilution with hemosome in awake rats.

Our study showed that hemodilution with modified fluid gelatin resulted in an increase in local cerebral blood flow (LCBF), but no change at all in local cerebral oxygen delivery (LCOD) in rats. Hemosome, a lecithin encapsulated hemoglobin having the oxygen-carrying capacity, was developed to improve LCOD by hemodilution. Therefore, we have hypothesized that LCBF & LCOD would be increased by hemodilution with hemosome. To test this hypothesis, adult male Sprague-Dawley rats weighing approximately 350g were used and divided into the hemodilution and the control groups. Hemosome was made from pig red blood cells and lecithin. It's mean diameter was approximately 0.3 um and hemoglobin concentration was approximately 4g/dl. Isovolemic hemodilution, which lowered the systemic hematocrit from approximately 50% to approximately 30%, was achieved by rapidly replacing blood with the same volume of hemosome. Ten min later, LCBF in 14 brain structures were measured using the 14C-iodoantipyrine technique. Our results showed that LCBF of the control group ranged from 115 +/- 11 ml/100g/min in the medulla to 260 +/- 31 ml/100g/min in the occipital cortex. LCBFs were generally higher (p < 0.05, MANOVA) by 16% in the hemodilution group than in the control group. However LCODs were generally decreased (p < 0.05, MANOVA) by 18% in the hemodilution group than in the control. In conclusion, hemodilution with hemosome indeed improves LCBF but lowers LCOD in awake rats.

Analysis of Variance↗
PubMed1996

Evaluation of laser and radiofrequency induced dorsal root entry zone lesion for pain control in rats.

BACKGROUND: Dorsal root entry zone (DREZ) lesions have been believed to be effective for control of intractable pain. These lesions are usually made using radiofrequency (RF) technique. Theoretically, laser can provide very fast, precise, reproducible and easy control of photothermal effect, possibly achieving better pain control than RF. The objective here was to learn more about the effect of pain control among the RF, carbon dioxide (CO2) laser and potassium titanyl phosphate (KTP) laser in rats. METHODS: The adult rat was anesthetized and the dorsal spinal cord from C5 to T1 was exposed under a microscope. The DREZ lesions were created in each group of eight including sham, RF thermocoagulation, CO2 laser and KTP laser. The latency of pain withdrawal in the fore-paw by a hot-plate test was recorded before the DREZ lesions and three weeks afterward. RESULTS: The data showed that RF, CO2 and KTP laser could significantly reduce pain in rats (p < 0.05, one-way ANOVA and Dunnett's test). Latencies of pain withdrawal in the fore-paw by the hot-plate test before, and three weeks after, DREZ lesions were 13.9 +/- 1.4 sec and 65.2 +/- 4.9 sec in the RF group, 15.9 +/- 1.4 sec and 59.0 +/- 5.9 sec in the CO2 laser group, and 14.1 +/- 0.9 sec and 64.8 +/- 5.7 sec in the KTP group, respectively. CONCLUSIONS: The density of opioid receptor in DREZ lesions cord showed no significant change three weeks after operation in the sham and CO2 laser groups. It was concluded that DREZ lesions caused by RF, CO2 laser and KTP laser can achieve pain control significantly in the rats. The effect of KTP laser was close to RF, followed by CO2 laser.

Animals↗
PubMed1996

[Cyclin-dependent kinase inhibitors in mammal cells].

In recent two years, a group of protein factors have been found to combine with the cyclin-dependent kinases (CDKs) and block the activation of cyclin/CDK complexes. They are named CDK inhibitors (CKIs) as p21, p16, p15, p27 and CDI1. The p21 and p27 have certain homology and can inhibit the activity of multiple CDKs; p16 and p15 have higher homology and can specifically combine with CDK4 and CDK6; and the combination specificity of CDI1 needs further research. The expression of p21 is regulated positively by p53. TGF-beta can upregulate the expression of p15 and the inhibitory activity of p27. The above findings demonstrate that CKIs are not only the regulators of CDKs' activity but also the direct linkers between cancer inhibitors and cell-cycle regulation.

Animals↗
PubMed1995

Intradural metastasis to the cauda equina from carcinoma of the anus.

STUDY DESIGN: This is a report of a man with carcinoma of the anus and intradural metastasis to the cauda equina. OBJECTIVE: To perform a laminectomy with tumor removal for relief of pain. SUMMARY OF BACKGROUND DATA: Only 25 cases of intradural spinal metastasis have been reported in the English literature. This is the first report of a metastatic case, moving from the carcinoma of the anus to the cauda equina. METHODS: Magnetic resonance imaging showed an ill-defined mass, with central necrosis, to the cauda equina. The possibility of intradural metastasis to the cauda equina was indicated by unique pain symptoms. RESULTS: The patient's back pain subsided after total laminectomy of L3-L5 with subtotal removal of the tumor. The residual tumor became smaller with postoperative radiation. CONCLUSION: Magnetic resonance imaging is a good diagnostic choice in this situation. The cause of the metastasis was unclear, but it was presumed to have occurred through the perineural lymphatic ducts. Laminectomy with tumor removal is feasible for relieving pain and demonstrating pathology.

Anal Canal↗
PubMed1995

Construction, purification, and functional incorporation on tumor cells of glycolipid-anchored human B7-1 (CD80).

To generate a potent cell-mediated immune response, at least two signals are required by T cells. One is engagement of the T-cell receptor with peptide-bearing major histocompatibility complex molecules. The other signal can be delivered by various molecules on the antigen-presenting cell, such as B7-1 (CD80). Many tumor cells escape immune recognition by failing to express these costimulatory molecules. Transfection of the B7 gene into some murine tumor cells allows for immune recognition and subsequent rejection of the parental tumor. We have studied an alternative approach for the introduction of B7-1 onto the surface of tumor cells. This method involves purified glycosyl-phosphatidylinositol (GPI)-anchored proteins which can spontaneously incorporate their lipid tail into cell membranes. We have created and purified a GPI-anchored B7-1 molecule (called GPI-B7) which is able to bind its cognate ligand, CD28, and incorporate itself into tumor cell membranes after a short incubation. Tumor cells that have been reconstituted with GPI-B7 can provide the costimulatory signal needed to stimulate T cells. These findings suggest an approach for the introduction of new proteins onto cell membranes to create an effective tumor vaccine for potential use in human immunotherapy.

Animals↗
PubMed1995

Brown-Séquard syndrome associated with Horner's syndrome in cervical epidural hematoma.

STUDY DESIGN: This report analyzed the likely locations of lesions that cause a combination of Horner's and Brown-Séquard syndromes. One must know the anatomic structure of spinal cord and the sympathetic nerve chain. OBJECTIVES: A hypertensive patient had Brown-Séquard and Horner's syndromes after neck trauma. The magnetic resonance imaging and surgical findings showed the correlation between the clinical symptoms and the likely lesion. METHODS: The patient underwent right hemilaminectomy from C2 to C6 with total removal of hematoma. CONCLUSION: The spinal epidural hematoma rarely is a surgical emergency. The patient presented with Brown-Séquard and Horner's syndromes. Magnetic resonance imaging made a rapid and correct diagnosis. The patient received an emergent right hemilaminectomy from C2 to C6 with removal of hematoma and subsequently made a complete recovery.

Brown-Sequard Syndrome↗
PubMed1995

Expression of heat-stable antigen on tumor cells provides co-stimulation for tumor-specific T cell proliferation and cytotoxicity in mice.

Heat-stable antigen (HSA/J11d/possibly homologous to CD24), a cell adhesion molecule capable of providing a co-stimulatory signal for T cell proliferation, is expressed on B cells, activated T cells, monocytes, granulocytes, Langerhans cells and thymocytes. Recent studies have demonstrated that co-stimulatory signals provided by cell adhesion molecules such as B7-1 play an essential role in generation of an anti-tumor immune response. To examine whether the co-stimulatory signal provided by HSA can induce an anti-tumor immune response, we have transfected HSA cDNA into the murine melanoma cell line K1735M2, and examined the ability of this transfected cell line to induce tumor-specific T cell responses. The results demonstrate that spleen cells from mice immunized with HSA-transfected K1735M2 cells showed enhanced T cell proliferation in a mixed lymphocyte tumor reaction (MLTR) assay and also demonstrated a significant anti-tumor cytotoxicity to the parent tumor cell (K1735M2). This anti-tumor cytolytic activity could be abrogated by pretreatment of effector cells with anti-mouse CD8 monoclonal antibody and complement. Under similar conditions, spleen cells from C3H mice immunized with vector-transfected K1735M2 cells neither actively proliferate in an MLTR assay, nor did they exert significant cytolytic activity against the respective tumor cells. In summary, our study demonstrated that HSA can provide a co-stimulatory signal for the T cell immune response against tumor cells in a murine model.

Animals↗
PubMed1995

Magnocellular and parvocellular divisions of pigeon nucleus isthmi differentially modulate visual responses in the tectum.

The electrophysiological responses of 162 tectal cells to computer-generated visual stimuli were extracellularly recorded from 24 homing pigeons before and after injecting either lidocaine or N-methyl-D-aspartate (NMDA) into the nucleus isthmi pars magnocellularis (Imc) or the nucleus isthmi pars parvocellularis (Ipc). Micro-injections of lidocaine into Imc resulted in a significant reduction of firing rate in 80% of tectal cells, whose excitatory receptive fields (ERFs) were localized within the ERF of the Imc cell where the lidocaine was injected. In contrast, when lidocaine was injected into Ipc under identical circumstances it had no effect on the visually driven activity of 68% of tectal cells. However, when the excitatory amino acid NMDA was injected into Ipc it produced a significant reduction in the visually driven firing of 75% of tectal neurons when their ERFs were within the isthmic ERF, while similar application of NMDA into Imc had no effect on the visually driven response of 94% of tectal neurons. When the ERFs of tectal cells were localized outside the ERF of the isthmic cell where the chemical was injected, Imc-injected lidocaine had no effect in 9 out of 10 tectal cells, whereas Ipc-injected NMDA increased firing in 7 out of 17 tectal cells. Therefore, it is suggested that the Imc-tectal fibers participate in a positive feedback pathway and the Ipc-tectal fibers are involved in a negative feedback pathway.

Anesthetics, Local↗
PubMed1995

Dose-dependent effects of chronic amphetamine administration in local cerebral glucose utilization in rat.

The daily dose of amphetamine pretreatment may affect the development of behavioral-sensitized patterns in rodents and amphetamine psychosis in humans. This experiment investigated the regional cerebral metabolic changes in rats after pretreatment with different doses of amphetamine by the 2-[14C]deoxyglucose method. Rates of local cerebral glucose utilization were examined in 37 regions of the rat brain. The result showed generally maximal metabolic augmentation in the 5.0 mg/kg group instead of in the 1.0 or the 10.0 mg/kg groups. Behavioral testing using motor activity cages in rats with the same regimen found no difference among groups. The findings demonstrate that there might be a window effect by daily amphetamine dose on the development of drug dependence and amphetamine psychosis. It was suggested that the 2(-)[14C]deoxyglucose method could be used for further study of animal models of amphetamine psychosis.

Amphetamine↗
PubMed1995

Decompressive craniotomy for acute shaken/impact baby syndrome.

To estimate the surgical efficacy of decompressive craniotomy, 23 children under 2 years of age with acute shaken/impact baby syndrome were treated with medical or surgical methods over the past 6 years. Six children (group A) with lower intracranial pressure (ICP, less than 30 mm Hg) were treated with medical therapy, and 17 children with high ICP (more than 30 mm Hg) of which 7 children were treated with medical therapy (group B) and another 10 children (group C) were treated with decompressive craniotomy. Bifrontal craniotomy was performed on 5 children with generalized brain swelling. A large frontotemporoparietal craniotomy was performed on another 5 children with unilateral swelling. A mean of 32 ml of subdural hematoma was removed. The mean ICP was reduced by 80% in the craniotomy group, p < 0.05. Children in groups A and C performed better on the Children's Outcome Scale than those in group B, p < 0.05. Mortality was significantly lower (0/10) in group C than in group B (3/7), p < 0.05. Hearing preservation was better in group C than in group B, p < 0.05. Bifrontal and frontotemporoparietal craniotomies may reduce mortality and morbidity for acute shaken/impact baby syndrome with high ICP. Patients with ICP less than 30 mm Hg may be treated successfully with medical therapy and patients with ICP more than 30 mm Hg are better treated with decompressive craniotomy.

Battered Child Syndrome↗
PubMed1995

Comparison of APACHE III, II and the Glasgow Coma Scale for prediction of mortality in a neurosurgical intensive care unit.

OBJECTIVES: This study examined the efficacy of predicting power for hospital mortality of three different scoring systems in a neurosurgical intensive care unit (NICU). SETTING: An eight-bed NICU in a 1,270-bed medical centre (Taichung Veterans General Hospital). SUBJECTS: Two hundred patients with head injury, brain tumour, hypertensive intracerebral haemorrhage, rupture of aneurysm or arteriovenous malformation, or other categories were included in our study in a consecutive period of 14 months. Patients less than 14 years old were not included. DESIGN: On the first day of admission, data were collected from each patient to compute the Acute Physiology and Chronic Health (APACHE) II and III, and Glasgow Coma Scale (GCS) scores. Hospital mortality was defined as when death occurred before discharge from hospital. INTERVENTIONS: none. MEASUREMENTS: Sensitivity, specificity and correct prediction outcomes were measured by logistic regression in three scoring systems. The Youden index was also obtained. The best cutoff point in each scoring system was determined by logistic regression or by the Youden index. Data obtained by logistic regression were compared by McNemar's test. The differences in Youden index were calculated by the Student's t-test. The area under the Receiver Operating Characteristic (ROC) curve was computed and the area of each scoring system was then compared by the Wilcoxon Mann-Whitney test. MAIN RESULTS: The correct prediction of outcome was 85.5% in APACHE III, 77.5% in APACHE II and 75.0% in GCS. The area under the Receiver Operating Characteristic (ROC) curve was 0.892 in APACHE III, 0.826 in APACHE II and 0.868 in GCS. For the prediction of dead patients at the best cutoff point, APACHE III and GCS were better than APACHE II, (both p < 0.01 respectively). For the prediction of alive patients at the best cutoff point, APACHE III was better than GCS and APACHE II (p < 0.01 respectively). CONCLUSION: The APACHE III system seems to be the most reliable. The results reveal that the APACHE III system is better in predicting power for hospital mortality than either the GCS or APACHE II systems in our NICU patients.

APACHE↗
PubMed1995

Magnetic resonance imaging of acoustic schwannomas.

The magnetic resonance imaging (MRI) findings of 27 histologically proven acoustic schwannomas in 24 patients (13 men, 11 women, age 20-79 yr) are described in detail. Three patients had bilateral tumors. Twenty-two tumors (82%) had intra- and extracanalicular components, three tumors (11%) were limited to the internal auditory canal (IAC) and two tumors (7%) were limited to the cerebellopontine angle (CPA). The diameters of extracanalicular lesions in the CPA ranged from 12 to 50 mm, and most of them were round in shape. All IAC portions of CPA tumors had a funnel-shaped appearance on the axial images and short-club-shaped configuration on the coronal images. There was strong homogeneous contrast enhancement of the solid components in 12 tumors (44%) and heterogeneous enhancement in 15 tumors (56%). The cystic components of the tumors correlated well with the histologic features. All tumors could be demonstrated in their enterity by MRI. The "short-club sign", first described in this study, helped to confirm the intracanalicular component of acoustic schwannomas, which were usually found in the cerebellar cistern. The results of this study show that MRI is a sensitive imaging modality for the assessment of acoustic schwannomas located at the CPA or IAC, or in both regions. MRI is non-invasive and does not involve ionizing radiation. It should be considered the imaging examination of choice to evaluate patients with suspected acoustic schwannomas.

Adult↗