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Biomedical subjects

J C Lin

Publications and source records attributed to J C Lin.

At least 145 records · Page 8Linked to original sources
PubMed1995

Geographic sequence variation of latent membrane protein 1 gene of Epstein-Barr virus in Hodgkin's lymphomas.

To assess the role of the Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) gene in the development of Hodgkin's lymphoma (HL), the polymorphism of this gene in EBV isolates from different geographic locations was analyzed. A 497 bp fragment spanning LMP1 gene exons 1 and 2 was amplified by polymerase chain reaction (PCR), using a primer pair bracketing a Xhol restriction site. PCR products were subjected to Xhol digestion and to DNA sequencing analysis. Twenty-five HL biopsy specimens from the United States and five HL and four non-Hodgkin's lymphoma (NHL) biopsy specimens from Italy were examined. Eighty percent of LMP1-positive samples (12 of 15) from the United States maintained the Xhol restriction site and the remaining 20% partially lost the Xhol site. One of four EBV-positive HL and one of the three EBV-positive NHL specimens from Italy lost the restriction site. The other three EBV-positive HL DNAs were partially cut by Xhol. Direct DNA sequencing analysis revealed that those Italian samples not digested by Xhol were due to a G to C transversion at the first base of codon 18, resulting in the change of glycine to arginine. Those DNA samples partially cut by Xhol were due to a mixture of G/C at the same location. In contrast, those partially digested American HL DNAs had a mixture of G/T at the second base of codon 17.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1995

Human ventromesencephalic grafts restore dopamine release and clearance in hemiparkinsonian rats.

We and others reported previously that transplantation of fetal ventromesencephalic homograft restores the apomorphine-induced rotational behavior and electrochemical indices of dopamine (DA) depletion in the 6-hydroxydopamine (6-OHDA)-lesioned rat. We found that regeneration of KCl-evoked DA release and tyrosine hydroxylase (TH) immunoreactivity was limited to the graft area even 4 months after transplantation. In the present experiments, we transplanted human fetal ventromesencephalic tissue to the 6-OHDA-lesioned rats. After transplantation, rats received chronic cyclosporin and vibramycin treatment. We found that human fetal grafts from the substantia nigra can restore the effects of DA depletion in 6-OHDA-lesioned rats; these fetal grafts were found to reduce the apomorphine-induced rotational behavior and restore K(+)-evoked DA release as well as DA clearance in the striatum. The area with active DA release is far beyond the transplantation site, unlike that seen in the homografted rats. These electrochemical responses correspond to the extended outgrowth of TH-positive neuronal fibers distal to the graft area. Taken together, our data suggest that rats that received human mesencephalic graft had much greater DA innervation and more complete restoration of function than those that received homografts.

Animals↗
PubMed1995

Methamphetamine facilitates ethanol-induced depressions in cerebellar Purkinje neurons of prazocin- or DSP4-treated rats.

Methamphetamine (MA) and ethanol (EtOH) are two commonly abused drugs. Previous behavioral studies indicated that MA may synergistically alter EtOH responses. In the present study, we found that local application of MA did not potentiate ethanol-induced depressions of the spontaneous activity of Purkinje neurons in urethane-anesthetized rats. We and others previously found that, in cerebellar Purkinje neurons, EtOH and gamma-amino-butyric acid (GABA)-mediated depressions can be enhanced by norepinephrine (NE) acting via beta-adrenergic receptors while these responses are decreased by activation of alpha-adrenergic receptors. In the present experiment, after blocking alpha-adrenergic receptors with prazocin, MA significantly enhanced EtOH responses in most of neurons studied. It has been reported that MA may directly and indirectly enhance alpha-adrenergic and beta-adrenergic receptor-mediated responses. The present study may suggest that MA can negatively modulate (antagonize) the depressant effects of ethanol via the alpha-adrenergic receptor, which oppose the positive modulatory mechanism (potentiation of EtOH depression) via actions of the beta-adrenergic receptors. We found that lesioning NE neurons with N-chloroethyl-N-ethyl-2-bromobenzylamine hydrochloride (DSP4), a selective noradrenergic neurotoxin, enhance the MA-facilitated ethanol responses, suggesting that this action of MA may not require NE. Since it has been reported that MA increases serotonin (5-HT) and catecholamine release from their nerve terminals, MA may potentiate EtOH depressions by facilitating the release of NE and 5-HT. Taken together, our data suggested that MA may modulate EtOH responses via catecholaminergic and serotonergic mechanisms in cerebellar Purkinje neurons.

Action Potentials↗
PubMed1995

Surface characterization and ex vivo blood compatibility study of plasma-modified small diameter tubing: effect of sulphur dioxide and hexamethyldisiloxane plasmas.

The development of a small diameter artificial vascular graft or prosthesis is limited by rapid thrombus formation and subsequent embolization upon blood contact. Plasma surface modification was employed to modify the inner surface of small diameter low density polyethylene (LDPE) tubing without varying the outer surface chemistry and physical properties of the tubing. A sulphur dioxide (SO2) plasma was used to form sulphonate functionality on the surface. In addition, a hexamethyldisiloxane (HMDSO) plasma and different gas flow ratios of SO2-HMDSO gas mixture plasmas were used to form ultrathin polysiloxane-like coatings inside the LDPE tubing. X-ray photoelectron spectroscopy (XPS) indicated that the inner surface of the tubing can be modified uniformly with this treatment. In addition, XPS results showed that the percentage of sulphur atoms bound to two or three oxygen atoms (sulphone or sulphonate) increased with the SO2-HMDSO mass flow rate ratio. The blood compatibility of the plasma-modified model materials was evaluated using an ex vivo canine arteriovenous shunt model. Similar thrombogenicity was observed comparing the untreated control and the surfaces modified by HMDSO plasma and SO2-HMDSO gas mixture plasmas, despite the differences in surface chemistry. The SO2 plasma-modified surface, which is the most hydrophilic as measured by the captive bubble contact angle measurement technique, was more thrombogenic than the untreated control. This may be attributed to the combined effect of the surface chemistry and surface hydrophilicity.

Animals↗
PubMed1995

Some nucleoside analogs with anti-human immunodeficiency virus activity inhibit replication of Epstein-Barr virus.

The effects of (+)-beta-D-dioxolane-cytosine ((+)-D-beta-DOC), (-)-beta-L-dioxolane-cytosine ((-)-L-beta-DOC), (+)-beta-D-oxathiolane-cytosine ((+)-D-beta-OTC), (-)-beta-L-oxathiolane-cytosine ((-)-L-beta-OTC, or 3TC), 3'-azido-2',3'-dideoxy-5-methyl-cytidine (5-Me-AZDC), and 3'-azido-2',3'-dideoxyuridine (AZDU) on Epstein-Barr virus (EBV) DNA replication in vitro were tested in P3HR-1 cells. Two anti-EBV drugs, 3'-azido-3'-deoxythymidine (AZT) and 9-(1,3-dihydroxy-2-propoxymethyl)guanine (DHPG, or ganciclovir), were used as positive controls. The inhibitory effects on EBV DNA synthesis were quantified by membrane filter and Southern blot hybridizations with an EBV-specific probe BamHI-W fragment. The 50% effective doses (ED50) for EBV DNA replication were 0.15, 0.83, 1.5, 8.3, 14, and 7.7 microM for DHPG, (-)-L-beta-DOC, (+)-D-beta-DOC, (+)-D-beta-OTC, (-)-L-beta-OTC, and AZT, respectively. In contrast, 5-Me-AZDC and AZDU were not effective at concentrations as high as 30 microM. These results indicated that both (-)-L-beta-DOC and (+)-D-beta-DOC were more potent than AZT, which has previously been shown to have anti-EBV activity. (-)-L-beta-DOC and (+)-D-beta-DOC have also been previously demonstrated to suppress the infectivity of human immunodeficiency virus type 1 (HIV-1). Thus, (-)-L-beta-DOC represents the first nucleoside analog with L-configuration exhibiting significant antiviral activities against both EBV and HIV.

Antiviral Agents↗
PubMed1995

Cardiovascular effects of NMDA in the RVLM of spontaneously hypertensive rats.

In this study we found that cardiovascular effects were differentially regulated by N-methyl-D-aspartate (NMDA) in the rostral ventral lateral medulla (RVLM) of spontaneously hypertensive rats (SHRs) compared to their normotensive controls (Wistar-Kyoto rats, WKYs). Adult SHRs and WKYs were anesthetized with urethane, cervically vagotomized, and placed in a sterotaxic frame. We found that electrical stimulation or local application of N-methyl-D-aspartate into the RVLM produced hypertension in both strains. Microinjection (3.5-4.0 nmol) of AP5 (2-amino-5-phosphono-valerate), an NMDA receptor antagonist, to the RVLM did not affect resting blood pressure; however, this agent antagonized hypertensive responses evoked by low-frequency electrical stimulation (5-20 Hz) in both strains. The elevation in blood pressure evoked by stimulation at a higher frequency (60 Hz) was not affected by AP5. These results suggest that NMDA receptors are involved in the low frequency, electrically evoked hypertension in both strains. We also found that SHRs had a larger pressor response to microinjection of NMDA and electrical stimulation than did WKYs. AP5 abolished the differences in evoked hypertension between WKYs and SHRs during low-frequency (5-10 Hz) electrical stimulation. These data suggest that the hypersensitivity of RVLM to low-frequency electrical stimulation in SHRs involve NMDA receptors. We previously reported that AP7 antagonizes NMDA and carotid clamping-induced hypertension. In this study, we found that when locally applied to RVLM, AP5 antagonized hypertension evoked by clamping the carotid arteries in SHRs and WKYs. Thus, carotid clamping-induced hypertension may also involve NMDA receptors in the RVLM.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Amino-5-phosphonovalerate↗
PubMed1995

Growth factor modulation of the formation of a molded vascularized bone graft in vivo.

Peptide growth factors are potent regulators of osteoblast differentiation, proliferation, and maturation. Two of these growth factors, transforming growth factor beta (TGF-beta) and basic fibroblast growth factor (bFGF), were used in an attempt to stimulate osteoneogenesis and angiogenesis in a molded vascularized bone graft in the rat. Custom chambers containing cancellous autograft bone and agarose beads and incubated with TGF-beta, bFGF, or a control solution, were closed around the femoral artery/vein pedicle for 2-4 weeks. Control grafts were completely necrotic and without mechanical integrity. TGF-beta grafts demonstrated active osteogenesis around necrotic bone, osteoclastic activity, and limited angiogenesis. Basic FGF grafts demonstrated substantial angiogenesis with limited osteoblastic activity. This study suggests that TGF-beta and bFGF stimulate populations of cells in the formation of a molded vascularized bone graft. TGF-beta induces the proliferation and/or activity of osteoblastic cells, while bFGF stimulates cells involved in angiogenesis. Despite these findings, an insoluble demineralized matrix component may be required for complete transformation and graft consolidation.

Animals↗
PubMed1995

Neoadjuvant chemotherapy for advanced nasopharyngeal carcinoma.

Between October 1990 and November 1991, a total of 16 male patients with advanced nasopharyngeal carcinoma were treated by neoadjuvant chemotherapy before conventional radiotherapy. They belonged to the AJCC stage IV with multiple bulky neck nodes metastases. The chemotherapy consisted of bleomycin, epirubicin, and cisplatin. Six patients completed 3 cycles, 9 patients finished 2 cycles, and 1 patient received 1 cycle of chemotherapy. Seven of the 16 patients (44%) were in complete response, and 50% (8/16) achieved partial response. The overall response rate was 94%. The major toxicities consisted of leucopenia (12/37 cycles had grade III-IV), nausea/vomiting, alopecia. Aplastic marrow developed in 1 patient, and one died of bleomycin-induced pneumonitis. Subsequent radiation therapy was well tolerated. After a minimal follow-up time of 24 months, the 2-year actuarial survival rate was 56%. Although we confirmed the impressively high response rate of this regimen, the toxicities were high and most patients failed at distant site(s). The efficacy of neoadjuvant chemotherapy for advanced nasopharyngeal carcinoma is doubtful and should be further studied in prospective randomized trials.

Actuarial Analysis↗
PubMed1995

Detection of human papillomavirus DNA in colorectal carcinomas by polymerase chain reaction.

Human papillomaviruses (HPVs) are associated with a number of benign and malignant neoplasms. To substantiate the relationship between HPV DNA and colorectal carcinomas, 70 carcinomas and 37 adenomas were analysed in this study. Specific types of HPV DNA in colorectal tumours were detected by polymerase chain reaction (PCR) and Southern blot hybridisation. HPV DNA was detected in 11 of 37 (29.7%) adenomas and in 52.9% 37 of 70 (52.9%) of carcinomas. The expression of HPV DNA in adenomas and carcinomas, especially that of HPV 16 in HPV positive cases (4 of 11 v 26 of 37), was significantly different (p < 0.05). There was no correlation, however, between HPV and the location, differentiation, stage, or survival of malignant neoplasms. These data suggest that HPV DNA, especially type 16, is associated with colorectal carcinogenesis.

Adenoma↗
PubMed1995

Vertebral artery dissection complicated by cervical manipulation: a case report.

A 32-year-old healthy man developed vomiting, blurred vision, and consciousness disturbance following cervical manipulation. Physical examination showed stuporous consciousness and spontaneous horizontal nystagmus. Computed tomography (CT) and magnetic resonance (MR) imaging of the brain revealed infarction in the territory of the basilar artery. Studies of MR angiography and vertebral angiography disclosed dissection of the right vertebral artery at the atlantoaxial segment. Antiedematous drugs were prescribed and the patient gradually improved. Neurologic examination six months later demonstrated mild cerebellar ataxia. Physicians and patients should be aware that vertebro-basilar dissection may follow cervical manipulation, and, more importantly, should attempt to prevent progressive infarction.

Adult↗
PubMed1994

Expression of the estrogen receptor in human thyroid neoplasms.

The expression and quantitation of the estrogen receptor (ER) in human thyroid tumors were examined by biochemical, immunohistochemical, and reverse transcriptase-polymerase chain reaction (RT-PCR) techniques. For this study, neoplasms, adenomatous goiters and adjacent normal thyroid tissues were obtained from 35 patients which included 10 cases of papillary carcinomas, 17 cases of adenomas and 8 cases of adenomatous goiters. Regardless of the histopathological subtype, ER was detected in 19% (5/27) of the neoplastic tissues with the mean value of ER content of 5.0 +/- 1.3 fmol/mg protein and the mean Kd value of 0.38 +/- 0.28 nM. ER was also detected, but at a lower concentration (2.8 +/- 1.6 fmol/mg protein), in the surrounding normal tissues. There was no significant difference between the neoplasms and adenomatous goiters with respect to the incidence of ER positivity and ER content. Furthermore, ER-positive specimens, as determined by both biochemical and immunohistochemical techniques, also showed the expression of ER mRNA detected by RT-PCR method. These results demonstrate that both ER mRNA as well as ER protein are expressed in thyroid neoplasms. This suggests the possibility that estrogen may affect the tumorigenesis or the progression of some thyroid neoplasms.

Adenoma↗
PubMed1994

Ki-ras oncogene activation in transplantable rat thyroid carcinoma induced by N-bis(2-hydroxypropyl)nitrosamine.

We have established 17 transplantable rat thyroid carcinoma cell lines from primary thyroid tumors of rats induced by N-bis(2-hydroxypropyl)nitrosamine (DHPN) (Cancer Res. (1993) 53, 4408-4412). The present study was designed to evaluate point mutations in the murine c-Ki-ras gene of these carcinoma cell lines. Using PCR amplification and direct sequencing, we found that the activated form of the Ki-ras oncogene was present in 4 (23%) of a total of 17 cell lines, all the Ki-ras gene mutations being GC-->AT transitions. In three of the cell lines, the mutations occurred in codon 12 (GTP-binding domain), and in the remaining one the first nucleotide of codon 63 was affected. Histologically, three of the carcinomas with Ki-ras mutation were diagnosed as well-differentiated carcinomas, and the other as poorly differentiated carcinoma. Mutations of the ras gene are relatively uncommon in tumors of these histological types. From these experimental results, we suggest that the mutation induced by DHPN is due to damage to guanine in cellular DNA. In addition, Ki-ras activation may play an important role in the initiation of thyroid carcinogenesis.

Animals↗
PubMed1994

Cholecystokinin facilitates methamphetamine-induced dopamine overflow in rat striatum and fetal ventral mesencephalic grafts.

The purpose of this study was to investigate the interactions of sulfated (S) and unsulfated (US) cholecystokinin (CCK) and methamphetamine (MA)-induced dopamine (DA) overflow in rat striatum. High-speed chronoamperometric recording techniques, using Nafion-coated carbon fiber electrodes, were used to evaluate extracellular DA concentration. CCK-8S, CCK-8US, MA, and DA were locally applied directly to the striatum of urethane-anesthetized Sprague-Dawley rats. We found that CCK potentiated MA-induced DA release in the anterior striatum. This response is probably mediated through CCK-A receptors because CCK-8S, but not CCK-8US, enhanced MA-induced responses. Replacement of Ca2+ with Mg2+ in the drug barrel antagonized this reaction, suggesting that the modulation of MA-induced DA release by CCK is Ca2+ dependent. Both MA-induced DA release and CCK modulatory effects disappeared in the striatum after unilaterally lesioning the medial forebrain boundle with 6-hydroxydopamine (6-OHDA). We had previously found that the zone of normalized dopamine clearance in 6-OHDA-lesioned rats was considerably larger than that of normalized release in the anterior striatum after fetal ventral mesencephalic (VM) transplantation, which may be a result of partial reinnervation from the transplant. In the present study, we found that the modulation of DA release by CCK was restored only in the zone of normalized release after fetal nigral transplantation; CCK did not increase MA-induced DA release throughout the larger partially innervated area. In conclusion, these findings suggest that not only DA release processes but also CCK modulatory mechanisms are restored in the anterior striatum after fetal VM transplantation.

Animals↗
PubMed1994

Functional characterization of partially purified Epstein-Barr virus DNA polymerase expressed in the baculovirus system.

The DNA polymerase gene of Epstein-Barr virus (EBV) was cloned into baculovirus transfer vector (pBlueBac). The recombinant baculovirus (AcEBP-15) was obtained by cotransfection of Spodoptera frugiperda (Sf9) cells with infectious DNA from Autographa californica multiple nuclear polyhedrin virus (AcMNPV) and pBlueBac plasmid carrying EBV polymerase gene. Infection of Sf9 cells with the recombinant virus produced substantial quantities of the EBV DNA polymerase protein of the expected size (110 kD). The identity of the EBV polymerase 110-kD polypeptide was determined by (a) immunoprecipitation and Western blot analyses with rabbit polyclonal antiserum specific for a synthetic peptide derived from the coding sequence of the polymerase gene; (b) identification of a polypeptide of identical size (110 kD) from EBV-infected cells; (c) measurement of DNA polymerase activity similar to that of the enzyme induced in EBV-infected cells; and (d) neutralization of the enzymatic activity by the rabbit antiserum and inhibition by phosphonoacetic acid. Our results indicate that the baculovirus expression system provides large quantities of functional polymerase suitable for biochemical and structural analyses, thereby furthering our understanding of the mechanism of viral DNA replication and its inhibition by antiviral drugs.

Amino Acid Sequence↗
PubMed1994

Non-surgical retrieval of intravascular foreign body: experience of 12 cases.

An intravascular foreign body is an iatrogenic complication that occurs during arterial or venous catheterization or interventional procedures. The foreign body could either be a catheter fragment, a dislodged coil, or a steel guide wire. From January 1987 to December 1992, 12 cases of intravascular foreign-body removals were performed by a percutaneous method at Mackay Memorial Hospital. Of the 12 cases, five were dislodged steel guide wires, four were broken CVP catheters, two were dislodged coils, and one was Port-A fragment. The techniques we used were the loop-snare technique (two cases) and stone basket retriever (10 cases). Eleven cases of intravascular foreign bodies were removed by non-surgical percutaneous retrieval but one case was a failure due to improper extraction of a dislodged steel guide wire. The patient received surgical extraction by regional venotomy finally. No major complications were noted during or after these procedures.

Adolescent↗
PubMed1994

Flow cytometric DNA analysis of colorectal carcinoid.

We analyzed the patterns of DNA ploidy in 31 colorectal carcinoid tumors from paraffin-embedded tissues by DNA flow cytometry and the relationship of the patterns of DNA ploidy to prognosis. Diploid DNA was found in 78% (24 of 31) of carcinoids and tetraploid in 6% (2 of 31). Five (16%) carcinoids were DNA aneuploid, and four of the patients with aneuploidy showing a near-hypertriploid pattern died during the first 5 years of follow-up. The association of aneuploidy with stage, size, and invasion of tumor was significant. However, our data indicated that DNA aneuploidy of a near-hypertriploid pattern was the most precise and reliable parameter for predicting the prognosis of colorectal carcinoid tumors.

Adult↗
PubMed1994

A strategy for precision of genotyping of Epstein-Barr virus by polymerase chain reaction: application for studying Hodgkin's lymphoma.

Previous studies on the genotyping of Epstein-Barr virus (EBV) have been based on the analysis of a single gene locus. The assignment of genotype of an isolate could easily be over-looked with this assay. Our strategy for precision of EBV genotyping has exploited the existence of two families of EBV strains (type A and B) that can be distinguished at three divergent gene loci (EBNA-2, EBNA-3C, and EBER). To precisely determine the genotype of EBV in Hodgkin's disease (HD), we designed primers and simultaneously analysed these three gene loci that distinguish type A and B viruses by the polymerase chain reaction (PCR) technique. The primers designed to amplify these three gene loci encompass either type-specific deletion sequences (EBNA-2 and EBNA-3C) or type-specific point mutations (EBER) that identify the virus strain based on the sizes of PCR-amplified products or the mobility shifts in single-strand conformation polymorphism (SSCP) analysis. The locations of point mutations were identified by direct sequencing of the PCR-amplified DNA. Fifteen EBV-infected cell lines were analysed and a good correlation between EBNA-2 and EBNA-3C typing results was found. In contrast, approximately 33% of the cell lines analysed maintained type A sequences in EBNA-2 and EBNA-3C genes while carrying type B sequences in the EBER region. Data obtained from analysis of cell lines served as a reference for studying HD samples. EBV DNA was detected in about 70% of HD. Among the EBV-positive samples, 56% were associated with type A virus, 13% with type B, and 31% with dual viral sequences.(ABSTRACT TRUNCATED AT 250 WORDS)

Antigens, Viral↗