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Biomedical subjects

Q Chen

Publications and source records attributed to Q Chen.

At least 487 records · Page 27Linked to original sources
PubMed1997

Interstitial photodynamic therapy in the canine prostate.

OBJECTIVE: To determine the depth of tissue destruction and the minimum light dose required for necrosis in interstitial photodynamic therapy (PDT), as a prerequisite for the investigational therapy of patients. MATERIALS AND METHODS: Seven adult beagle dogs were given 2 mg/kg of the photosensitizer Photofrin intravenously and two controls received none. After 24 h, 450 J/cm of 630 nm wavelength laser light was delivered interstitially to the prostate via a 2 cm long diffuser fibre. Seven single-fibre treatments were performed in five sensitized dogs and two single-fibre treatments in the controls. The two remaining sensitized dogs had two fibres placed 10 mm apart within the prostate to determine the coalescence of PDT lesions. The penetration depth of light was measured in all prostates, and after PDT the extent of necrosis was assessed histologically. RESULTS: The mean (standard deviation, SD) radius of PDT destruction around each diffuser was 5.3 (1.4) mm and PDT lesions overlapped in prostates treated with two fibres placed 10 mm apart. There was no observable tissue damage in the controls. The mean (SD) minimum light dose required for PDT necrosis was 84 (64) J/cm2. Differences among animals in the light penetration depth were small, with a mean of 2.14 (0.2) mm, and did not correlate with the depth of necrosis (P = 0.07). Bleeding around the optical diffuser fibre impeded light penetration. CONCLUSION: Interstitial PDT in the canine prostate using Photofrin produced modest volumes of tissue necrosis. The minimum light dose required to induce necrosis was variable because bleeding was unpredictable in relation to the optical fibre.

Animals↗
PubMed1997

Comparative pharmacokinetics, tissue distribution, and tumor accumulation of phosphorothioate, phosphorodithioate, and methylphosphonate oligonucleotides in nude mice.

The goals of this study were to systematically compare the pharmacokinetics and tissue distribution of phosphorothioate (PS), methylphosphonate (MP), and phosphorodithioate (PS2) oligonucleotide analogs; 15-mers of sequence d-TAC GCC AAC AGC TCC (5'-3') complementary to the AUG region of K-ras were radiolabeled with carbon-14. Oligomers were administered as a single dose in the tail vein of nude mice harboring a K-ras-dependent human pancreatic tumor (CFPAC1). The kinetics of PS, PS2, and MP oligomer availability in the bloodstream was followed. Concentration versus time profiles for all oligomers were biphasic, indicative of a two-compartment model. A rapid distribution phase with t1/2 alpha values of 1 minute or less and an elimination phase with average t1/2 beta values of 24-35 minutes were observed. Volumes of distribution (Vd) were 3.2, 4.8, and 6.3 ml for PS2, MP, and PS, respectively, in comparison to 3.6 ml for sucrose, a fluid-phase marker. Relative tissue drug levels obtained at 1 and 24 hours after administration were kidney > liver > spleen > tumor > muscle. Total kidney and liver oligonucleotide accumulation was approximately 7%-15% of the initial dose, with tumor accumulating 2%-3%. Intact compound was recovered from all tissues, including tumor, as assessed by high-pressure reversed-phase HPLC coupled to radiometric detection. Integrity of the oligonucleotides ranged from 73% in blood to 43%-46% in kidney and liver. Kidney and liver appear to be the primary sites of metabolism. These results demonstrate widespread tissue availability of these compounds and suggest their development as potential antitumor agents.

Animals↗
PubMed1997

Molecular genetics of long QT syndrome from genes to patients.

Recently, there has been intense excitement in the field of cardiac arrhythmias. Molecular genetic studies have led to significant progress in characterizing molecular mechanisms underlying long QT syndrome, an inherited cardiac disorder that causes syncope, seizures, and sudden death from ventricular arrhythmias. Three long QT syndrome genes have been identified: SCN5A on 3p21-24, HERG on 7q35-36, and KVLQT1 on 11p15.5; all encode cardiac mycote ion channels. Molecular and electrophysiological characterization of these three long QT syndrome genes has led to identification of three critical electrical currents in the human heart (INa, IKr, IKa) and provides insight into our fundamental understanding of cardiac function. Genetic testing and gene-specific therapies are now available for some families with long QT syndrome.

Chromosome Mapping↗
PubMed1997

Causality of parenchymal and vascular changes in rats with experimental thiamine deficiency encephalopathy.

The causality of vascular and parenchymal damage to the central nervous system (CNS) was examined in rats with thiamine deficiency. Male Sprague-Dawley rats were divided into two groups; one was given a thiamine-deficient diet (TDD) and injected intraperitoneally with 10 micrograms/100 g bodyweight pyrithiamine (PT) in order to analyze morphometrically the topographical and sequential relationship between vascular and parenchymal changes and vasodilatation, and the other was given a TDD and 50 micrograms/100 g bodyweight PT in order to determine hemorrhagic sites using serial sections. Histological examination showed that spongiotic change occurred selectively in the inferior colliculus (100%) from day 19, and thereafter in the thalamus (95%), mammillary body (50%) and nuclei olivaris and vestibularis of the pons (25%), with or without hemorrhage. Simultaneously, glycogen accumulation was also observed in these regions at a frequency similar to that of hemorrhage. Ultrastructurally, however, hydropic swelling of astrocytic and neuronal processes without glycogen accumulation was observed as early as day 9 in the inferior colliculus, at which time an increase of glial fibrillary acidic protein-positive processes was also recognized. The superior colliculus was completely spared. From day 22 vasodilatation of the inferior colliculus occurred, concomitantly with bodyweight loss and neurological symptoms. Twenty-two examined hemorrhages, which occurred in the thalamus and inferior colliculus, were distributed along the arterioles or capillaries on the arterial side. In conclusion, the morphological CNS changes caused by thiamine deficiency with administration of low-dose PT in rats begin as hydropic swelling of neuronal and astrocytic processes, followed by hemorrhage and, thereafter, by vasodilation. The predilection for hemorrhage on the arterial side without parenchymal changes suggests that petechial hemorrhage is not simply secondary to parenchymal changes, but is due to hemodynamic change resulting from thiamine deficiency-induced vascular dysfunction.

Animals↗
PubMed1997

Menadione cytotoxicity to Hep G2 cells and protection by activation of nuclear factor-kappaB.

Menadione (vitamin K-3,2-methyl-1,4-naphthoquinone), a redox cycling reagent, generates reactive oxygen intermediates and causes oxidative injury. The addition of menadione to Hep G2 cells produced a time- and concentration-dependent loss of cell viability. Preincubation of Hep G2 cells with low, nontoxic concentrations of menadione increased the viability of the cells against toxic doses of menadione or H2O2. Maximum protection was found with menadione concentrations of approximately 3 microM and preincubation times of approximately 45 min. This protective effect could be blocked by the protein synthesis inhibitor cycloheximide and by a variety of antioxidants. The transcription factor nuclear factor-kappaF (NF-kappaB) is known to be activated by many compounds, including reactive oxygen intermediates. Menadione activated NF-kappaB as determined by electrophoretic mobility shift assays. This activation was prevented by the same antioxidants that blocked protection against cytotoxicity produced by preincubation with menadione. Anti-p50 IgG prevented the menadione-stimulated binding of NF-kappaB to the oligonucleotide probe, whereas anti-p65 IgG produced a supershift of the NF-kappaB/oligonucleotide complex. Salicylate prevented the activation of NF-kappaB by menadione, and under these conditions, salicylate potentiated the cytotoxicity of menadione or H2O2. Transfection with a plasmid containing cDNA encoding mouse IkappaBbeta, an inhibitor of NF-kappaB, resulted in increased toxicity by menadione. Furthermore, when protein kinase C was down-regulated by prolonged treatment with active phorbol ester (phorbol-12-myristate-13-acetate), the Hep G2 cells became more sensitive to menadione treatment. However, short term treatment with PMA, which activated NF-kappaB, resulted in protection against menadione cytotoxicity. Menadione cytotoxicity was enhanced when the Hep G2 cells were depleted of GSH. An increased level of GSH was observed after menadione pretreatment; this increase was blocked by salicylate, thereby linking the GSH increase to activation of NF-kappaB by menadione. The results of the current study suggest that menadione pretreatment protects Hep G2 cells from oxidative injury through an NF-kappaB-related mechanism, which may involve, in part, increased production of GSH.

Animals↗
PubMed1997

Immune suppression in calves with bovine immunodeficiency virus.

The present study was designed to evaluate the effect of bovine immunodeficiency virus (BIV) infection on immune functions and possible interactions between BIV and other bovine viruses in calves. Ten calves were inoculated intravenously with BIV, and five served as controls. An increased lymphocyte proliferation to BIV gag protein was demonstrated 2 to 6 weeks after BIV inoculation (P < 0.05). Lymphocyte subset differentiation revealed a decreased CD4/CD8 ratio (P < 0.05) during weeks 2 to 7, suggesting a possible immune dysfunction in BIV-infected calves. When the calves were inoculated with bovine herpesvirus type 1 (BHV-1), the antibody response to BHV-1 in BIV-infected calves was delayed and the antibody titers were significantly lower (P < 0.05). Injection of bovine viral diarrhea virus vaccine also elicited a lower neutralizing antibody response in BIV-infected calves. The results indicated that immune suppression occurred in BIV-infected calves.

Animals↗
PubMed1997

Different pathways mediate cholecystokinin actions in cholelithiasis.

Smooth muscle from gallbladders with cholesterol stones exhibits impaired response to cholecystokinin (CCK). This study investigated whether the impaired response is mediated by different signal-transduction pathways responsible for CCK-induced contraction in prairie dog and human gallbladders with cholesterol stones. Gallbladder muscle cells were isolated enzymatically to study contraction. Protein kinase C (PKC) activity was measured by examining the phosphorylation of a specific substrate peptide from myelin basic protein Ac-MBP-(4-14). Gallbladder muscle cells from high-cholesterol-fed prairie dogs contracted less in response to CCK octapeptide (CCK-8) than those from the control group. However, inositol-1,4,5-trisphosphate (IP3), diacylglycerol, and guanosine 5'-O-(3-thiotriphosphate) induced the same magnitudes of contraction in these two groups. In control prairie dog and human gallbladders, the maximal contraction caused by 10(-8) M CCK-8 was blocked by the calmodulin antagonist CGS9343B but not by the PKC inhibitor H-7. Conversely, in gallbladders with cholesterol stones from prairie dogs or human patients, the maximal contraction induced by 10(-8) M CCK-8 was blocked by H-7 and chelerythrine but not by CGS9343B. In these gallbladders CCK-8 caused a significant PKC translocation from the cytosol to the membrane. High CCK concentrations may activate the calmodulin-dependent pathway in functionally normal gallbladder muscle and the PKC-dependent pathway in muscle from gallbladders with cholesterol stones. The defect of gallbladder muscle after cholesterol feeding and stones might reside in the steps before G protein activation.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1997

An autocrine system for C-type natriuretic peptide within rat carotid neointima during arterial repair.

C-type natriuretic peptides (CNPs) are produced by endothelium and inhibit vascular smooth muscle cell (VSMC) proliferation. However, endothelial damage stimulates only transient VSMC proliferation in arteries. Here we report that a new source of CNP develops in rat carotid neointima 14 days after balloon angioplasty, when VSMC replication is subsiding despite continued absence of endothelium. CNP was detected immunohistochemically in neointimal but not medial VSMC. No other natriuretic peptides were detected immunohistochemically. CNP immunoreactivity (0.036 +/- 0.010 fmol/mg wet wt) was found in damaged arteries by radioimmunoassay, but none was detected in normal media. Reverse-phase chromatography suggested that this immunoreactivity consisted of CNP(1-53) and perhaps CNP(1-22). CNP transcript was identified by reverse transcription and polymerase chain reaction in carotid segments that had been stripped of endothelium but only once neointima had formed. Moreover, neointima expressed the NPR-C type of natriuretic peptide receptor at the same time as it synthesized CNP. Thus neointima develops an autocrine system for CNP that could regulate neointimal growth. Furthermore, the findings establish novel phenotypic differences between medial and neointimal VSMC in vivo.

Angioplasty, Balloon↗
PubMed1997

Detection of bovine immunodeficiency virus antibodies in cattle by western blot assay with recombinant gag protein.

A western blot assay using purified recombinant bovine immunodeficiency virus gag protein has been developed for detection of bovine immunodeficiency virus antibodies in bovine serum samples. The test was standardized with known bovine immunodeficiency virus positive and negative bovine serum samples and the monoclonal antibody to gag protein. Both naturally and experimentally infected cattle sera demonstrated positive test results. The result of western blot assay was compared with polymerase chain reaction test results in 134 blood samples collected from Kansas. Twenty-six samples tested positive for bovine immunodeficiency virus DNA with polymerase chain reaction (18.7%) and 25 were positive for the antibody to gag protein by western blot analysis (17.9%). Of 26 cattle testing positive using the polymerase chain reaction assay, 24 were antibody-positive by western blot assay, thus establishing a strong correlation between the two tests. The sensitivity and specificity of western blot relative to polymerase chain reaction are 0.92 and 0.99, respectively. The western blot assay proved to be a specific and sensitive test.

Animals↗
PubMed1997

Role of acid/base homeostasis in the suppression of apoptosis in haemopoietic cells by v-Abl protein tyrosine kinase.

Removal of interleukin-3 from murine IC.DP pre-mast cells results in irreversible commitment to apoptosis within 18 hours. To identify early events necessary for the engagement of apoptosis we examined the regulation of intracellular pH (pH(i)). IC.DP cells acidified 2 hours after removal of interleukin-3 (before discernible signs of apoptosis) and by 18 hours pH(i) had decreased by 0.15 units. The acidification was due to both an increase in an acid-loading process which only occurs when intracellular pH is above 6.8 and a slight reduction in H+ efflux via NA+/H+ exchange. Activation of a temperature sensitive mutant of v-Abl protein tyrosine kinase suppressed apoptosis of IC.DP cells in the absence of interleukin-3 but did not stimulate proliferation, and moreover prevented cellular acidification. Acidification of the cells by 0.2 units to pH 6.86 by complete inhibition of Na+/H+ exchange by 10 microM 5'-(N-methyl-N-isobutyl)-amiloride prevented the suppression of apoptosis by v-abl protein tyrosine kinase following IL 3 withdrawal. However in the presence of interleukin-3, addition of 10 microM 5'-(N-methyl-N-isobutyl)-amiloride only resulted in a fall of pH(i) to 7.17. Apoptosis did not occur and the cells continued to proliferate. Thus, in this model intracellular pH must fall below a critical value for apoptosis to occur. Together these data point to a step in cytokine deprivation induced apoptosis (at least in some haemopoietic cell types) which is either enhanced by or dependent upon an acidic intracellular environment which is the result of an increase in acid loading and inhibition of Na+/H+ exchange activity. One of the mechanisms by which activation of v-Abl protein tyrosine kinase suppresses apoptosis is by prevention of intracellular acidification.

Acid-Base Equilibrium↗
PubMed1997

Changes in in vivo optical properties and light distributions in normal canine prostate during photodynamic therapy.

The optical absorption and transport scattering coefficients of normal prostate tissue have been measured in vivo in dogs. The measurements were made at 630 nm before and during treatment by Photofin photodynamic therapy using interstitial optical fiber fluence-rate detectors. Corresponding measurements were made ex vivo, at 1 week after treatment, in the contralateral lobe. The optical properties were derived by applying a diffusion theory model to the fluence rates measured at two different source-detector fiber distances. While the in vivo pretreatment and in vivo contralateral post-treatment absorption and scattering values are self-consistent and in agreement with published data, significant changes were observed in the light fluence rates, and hence in the derived optical properties, during light irradiation. The possible causes of such changes are considered, and the implications for light dosimetry in photodynamic therapy are discussed.

Animals↗
PubMed1997

[A new type of intellectualized Y-maze].

This paper describes the hardware and software of an intellectualized Y-maze with a microcomputer, which controls the whole procedure of discrimination learning test for rats or mice. By monitoring the action of the animal with the infrared photoelectrical sensors, its determination is accurate and timing precise. Due to working on the platform of WINDOWS, the interface is friendly and the operation is convenient and simple.

Animals↗
PubMed1997

[The relationship between hemorrhagic dilation of the fourth ventricle and outcome].

52 adult patients with CT-documented fourth intraventricular hemorrhage (FIVH) were treated. The various etiologic findings included intraparenchymal hemorrhage with secondary FIVH (24 cases), spontaneous subarachnoid hemorrhage (8), spontaneous IVH (12), and trauma (8). Of the 52 patients, 28 died because of hemorrhagic dilation of the fourth ventricle in spite of aggressive therapy. Of the 24 FIVH patients without dilation, 10 died and 14 survived. The survival rate for the patients with hemorrhagic dilation of the fourth ventricle was significantly lower than that for FIVH patients without dilation. Of the 28 patients with FIVH associated with dilation, 24 presented with a Glasgow Coma Scale (GCS) score of less than 5 or 5, 2 with a GCS score of 7, and 2 with a GCS score of 13. In the 24 FIVH patients without dilation, 8 presented with a GCS score of 3 to 5 (seven died and one survived), 4 with a GCS score of 6 to 8 (two died and two had survival), 5 with a GCS score of 9 to 12 (one died and four had survival), and 7 with a GCS score of 13 to 15. There was a great difference of GCS scores between the two groups. Logistic regression multivariate analysis demonstrated that hemorrhagic dilation of the fourth ventricle was the most significant outcome predictor, followed by GCS score and then the presence of diffuse IVH.

Adolescent↗
PubMed1997

Treatment of acute pancreatitis with liyi tang--a report of 50 cases.

Fifty cases of acute pancreatitis (AP) were treated with LIYI TANG (Decoction for AP) as the treatment group, and the other 50 cases of the disease with Western drugs as the control group. The results of one-week clinical observation showed that, in the treatment group, 43 cases were cured, 3 markedly effective, 2 improved and 2 ineffective; while in the control group, 32 cases were cured, 5 markedly effective, 4 improved, and 9 ineffective, showing a statistically significant difference in therapeutic effects between the two groups (P < 0.05).

Acute Disease↗
PubMed1997

[Micro-vitreoretinal surgery and silicone oil for treatment of perforating injuries with retinal detachments].

OBJECTIVE: To evaluate the therapeutic value and effects of micro-vitreoretinal surgery (M-VRS), retinotomy and silicone oil (SiO) for perforating injuries with retinal detachment (PIRD). METHODS: 64 cases of PIRD were treated with M-VRS, retinotomies and SiO. RESULTS: The retina was totally reattached in 58 cases or a rate of 90.6%, which dropped to 73.5% in 3-15 months postoperatively. Visual acuity of 64.7% was counting fingers or better, and 17.6% > or = 0.05. CONCLUSIONS: This method can cure PIRD that were not cured with routine M-VRS, and 1/6 cases were out of blindness.

Adolescent↗
PubMed1997

[Factors for postoperative persistent hypertension in patients with aldosterone-producing adenoma].

We determined the factors for postoperative persistent hypertension in the patients with aldosterone-producing adrenal adenoma (APA) in 53 patients with APA who were followed up for average 3.1 years. All had normal serum potassium concentration postoperatively. Blood pressure was normal in 37 patients (69.8%) but 18.7/12.7 kPa or more in 16 patients (30.2%) with persistent hypertension. Also compared were sex, age, history of hypertension, effect of reducing blood pressure to antisterone, preoperative blood pressure, time of persistent hypertension, serum potassium concentration, aldosterone concentration in 24 hour urine, amount of PRA, and the type of operation. The results showed that an APA patient aged 50 years or more appears to have a great chance of persistent hypertension than an APA patient under age of 40 years, and the odds ratio is 3:1. There was a significant difference between the mean age for persistent hypertension and for normal blood pressure, and varioas response of reducing blood pressure to antisterone (P < 0.05). It is suggested that for an older APA patient and the patient without of reducing blood pressure to antisterone, there are other factors for hypertension such as renal veinlet change or renal interstitial lesions except for hyperaldosteronism. We recommend renal biopsy (using kidney puncture) at the operating table for those patients in order to understand pathological change and guide treatment after operation.

Adenoma↗
PubMed1997

[Study of PEFV curves in 520 normal middle-aged and old humans].

Partial expiratory flow-volume(PEEV) curves and other pulmonary functions were performed for 520 (20-86 yr) normal midde-aged and old humans. The regression equations of V at FRC (VFRC, volume corrected VFRC (VFRC/FVC), flows at various lung volumes (V75, V50, V25) and specific time constants (S tau 75, S tau 50, S tau 25) were built with multiple stepwise regression analysis. VFRC decreased with increase of age, but after correction with FVC, the correlation of VFRC/FVC with age decreased. The regressions were tested with substitution of parameters with normal persons and proved to be correct. This study suggests that PEFV curve with convenient method has theoretical and practical significance.

Adult↗