Biomedical subjects

M Nakashima

Publications and source records attributed to M Nakashima.

At least 181 records · Page 10Linked to original sources

PubMed1997

Optical recording of neural signals evoked by greater superficial petrosal nerve stimulation in rat.

Electrical responses to greater superficial petrosal (GSP) nerve stimulation in a rat geniculate ganglion (GG) preparation were assessed by simultaneous multi-site-optical recording. The GG/GSP nerve preparations were dissected out and were stained with a voltage-sensitive dye (RH155). Application of depolarizing square pulses to the GSP nerve fibers using a suction electrode evoked optical (absorbance) signals that were recorded simultaneously from many contiguous regions using a 24 x 24 photodiode matrix array with 448 active elements. Those optical signals were observed along the left half area of the GSP nerve. As the distance from the site of stimulation increased, the optical signals appeared to conduct with increasing time-delay. From the relationship between the peak latency and distance, the conduction velocity was estimated to be about 0.4 m/s. Tetraethylammonium affected the duration of the optical signals, and the signals disappeared in solutions containing tetrodotoxin (TTX) or in Na(+)-deficient solutions. The optical signals evoked by the GSP nerve stimulation are considered to be due to the action potentials propagating along the GSP of unmyelinated axons.

Afferent Pathways↗

PubMed1997

Effect of prostaglandin E1 on the rat inner ear microvascular thrombosis.

1. The effect of prostaglandin E1 was investigated with a two-rat model of hearing disturbance and equilibrium dysfunction associated with inner ear microvascular thrombosis. 2. The inner ear microvascular thrombosis was induced by photochemical reaction between Rose Bengal and transmural green light (540 nm). Photochemical reaction causes endothelial injury followed by platelet adhesion, aggregation, and formation of a platelet- and fibrin-rich thrombus. 3. Under anesthesia, the cochlea or the vestibule was irradiated with green light to induce hearing disturbance or equilibrium dysfunction. 4. In the hearing disturbance model, a compound cochlear nerve action potential was recorded by electrocochleography every minute after the beginning of photoirradiation in the presence of Rose Bengal. 5. In the equilibrium dysfunction model, the photoirradiation was applied for 10 min after Rose Bengal administration. The behavior of rats was observed in the swimming test, and nystagmus was observed 24 hr after the end of photoirradiation. 6. Prostaglandin E1 significantly (P < 0.05) prolonged the time required to suppress the action potential. In the swimming test, 3 of the 6 animals treated with prostaglandin E1 did not rotate about their longitudinal axes (equilibrium dysfunction) and the duration of well-balanced swimming was significantly prolonged (P < .001). Prostaglandin E1 significantly (P < 0.05) suppressed the appearance of nystagmus. 7. In conclusion, prostaglandin E1 potentially prevents hearing disturbance and equilibrium dysfunction due to inner ear microvascular disorders.

Action Potentials↗

PubMed1997

Cardiac and hemodynamic effects of TZC-5665, a novel pyridazinone derivative, and its metabolite in humans and dogs.

1. TZC-5665 is a novel pyridazinone derivative with vasodilatory and beta-adrenergic blocking activities and type III phosphodiesterase inhibitory action. 2. In healthy volunteers, TZC-5665 was rapidly absorbed and immediately metabolized. Its main metabolite, M-2, remained at a higher concentration in plasma. Orally administered TZC-5665 reduced end-diastolic left ventricular volume (20.16 ml) and exhibited a tendency to increase ejection fraction (0.04). 3. In dogs, M-2 dose-dependently increased cardiac contractility and reduced both preload and afterload. These effects appeared more potent in the failed heart than in the normal heart. At the same dose (30 micrograms/kg), the effects of M-2 seem to be more potent than those of milrinone. 4. We concluded that TZC-5665 is a useful medication for treating patients with chronic congestive heart failure (CHF) because of the positive inotropic and vasodilating effects due to its active metabolite in addition to its own beta-adrenergic blocking actions.

Adult↗

PubMed1997

A prospective, randomized, double-blind multicenter trial of a single bolus injection of the novel modified t-PA E6010 in the treatment of acute myocardial infarction: comparison with native t-PA. E6010 Study Group.

OBJECTIVES: This prospective, randomized, double-blind multicenter trial evaluated the efficacy and safety of a single bolus injection of the novel modified tissue-type plasminogen activator (t-PA) E6010 in the treatment of acute myocardial infarction compared with that of native t-PA. BACKGROUND: E6010 is a novel modified t-PA with a prolonged half-life (t1/2 alpha > or = 23 min) compared with native t-PA (t1/2 alpha = 4 min). E6010 can be administered in patients as a single intravenous bolus injection, and early recanalization can be expected. METHODS: The efficacy of E6010 was compared with that of native t-PA in 199 patients with acute myocardial infarction who were treated within 6 h of onset in a prospective, randomized, double-blind multicenter trial. Patients were given either 0.22 mg/kg body weight of E6010 intravenously over 2 min or native t-PA (tisokinase) 28.8 mg or 14.4 million IU (10% of the total dose over 1 to 2 min, the remainder infused over 60 min). RESULTS: The primary end point was the recanalization rate of the infarct-related coronary artery at 60 min after the start of treatment. Time to reperfusion was shorter in the E6010 group than in the native t-PA group. Thrombolysis in Myocardial Infarction flow grade 2 or 3 recanalization at 15, 30, 45 and 60 min after administration was observed in 37%, 62%, 74% and 79% (95% confidence interval [CI] 70% to 87%) of the E6010-treated patients and in 14%, 32%, 50% and 65% (95% CI 55% to 74%) of native t-PA-treated patients, respectively (p = 0.032 at 60 min). CONCLUSIONS: The present study indicates that, compared with native t-PA, a single bolus injection of E6010 over 2 min produces a higher rate of early recanalization of the infarct-related coronary artery without fatal bleeding complications.

Aged↗

PubMed1997

Enhanced effect of triazolam with diltiazem.

AIMS: Triazolam, a triazolobenzodiazepine hypnotic agent, is metabolized by CYP3A4. Diltiazem is an inhibitor of this isozyme. The aim of this study was to determine if diltiazem affects plasma concentrations of triazolam in humans. METHODS: We investigated the interaction between triazolam and diltiazem in a randomized, three-phase crossover study. Seven healthy male volunteers received orally either a single 0.25 mg dose of triazolam, a 0.25 mg dose of triazolam after a 3-day treatment of diltiazem (180 mg day-1), or a placebo. Plasma samples were collected to determine triazolam concentration over a 24 h period. The pharmacodynamic effects of triazolam were investigated using the peak saccadic velocity of eye movements (PSV), electroencephalogram (EEG), and visual analogue scale (VAS) through 8 h. RESULTS: Diltiazem pretreatment significantly increased the area under the triazolam concentration-time curve (8.0 +/- 2.4 to 18.2 +/- 3.1 ng ml-1 h; P < 0.001; mean +/- s.d.). Peak triazolam concentration was increased (2.1 +/- 0.7 to 3.6 +/- 1.0 ng ml-1, P < 0.05) and the elimination half-life prolonged (4.1 +/- 2.1 to 7.6 +/- 1.9 h; P < 0.01). The PSV, EEG, and VAS of the triazolam plus diltiazem group revealed significant differences from the triazolam alone group or the control placebo group. CONCLUSIONS: Diltiazem markedly affects the pharmacokinetics of triazolam and increases the intensity of its sedative effects. Inhibition of CYP3A isozyme by diltiazem may explain the observed pharmacokinetic interaction. Therefore, triazolam should be avoided when patients are using diltiazem.

Administration, Oral↗

PubMed1997

Pharmacokinetics and safety of JTP-4819, a novel specific orally active prolyl endopeptidase inhibitor, in healthy male volunteers.

AIMS: To investigate the pharmacokinetics and safety profile of JTP-4819, (-)-(2S)-1-benzylaminocarbonyl-[(2S)-2-glycoloylpyrrolidinyl ]-2-pyrrolidinecarboxamide, a novel specific orally active prolyl endopeptidase (PEP) inhibitor. METHODS: JTP-4819 was given orally to 28 healthy male volunteers at single doses of 30 mg (n = 6), 60 mg (n = 6), 120 mg (n = 6) and placebo (n = 3) and multiple doses of 60 mg three times daily (n = 5) and placebo (n = 2) for 7 days to investigate its safety and pharmacokinetics following a preliminary safety evaluation of 3, 10 and 30 mg doses in six healthy volunteers. With the single dose of 60 mg, a cross-over study was conducted to examine the effect of food on the bioavailability of the drug. The concentrations of JTP-4819 in plasma and urine were determined by electrospray ionization-liquid chromatography/mass spectrometry (ESI-LC/MS) method. RESULTS: In the multiple-dose study, the cholinesterase activity was gradually increased and reached above the normal range on days 4 to 8 in all five subjects given JTP-4819 and gradually returned to normal range after completion of dosing. The elevation of plasma cholinesterase activity was considered to be an action of JTP-4819, but this remains to be verified. There were no other abnormal findings in objective symptoms and laboratory findings including blood pressure, heart rate, electrocardiogram, body temperature, haematology, blood chemistry and urinalysis. The Cmax of JTP-4819 at 30, 60 and 120 mg in fasting state were 474, 887 and 1,649 ng ml-1, respectively, at 1 h after administration, and the t1/2 was about 2 h. AUC increased in proportion to the given doses. The cumulative urinary recoveries within 24 h were approximately 66%, Cmax, AUC, t1/2 and urinary recovery were not affected by food intake. In the multiple-dose study, there was no drug accumulation trend in plasma. CONCLUSIONS: These results indicate that JTP-4819 has acceptable pharmacodynamic and pharmacokinetics profiles for clinical use without any serious adverse events as we verified in healthy young male volunteers.

Administration, Oral↗

PubMed1997

Effects of pemirolast and tranilast on intimal thickening after arterial injury in the rat.

We previously reported that tranilast, an antiallergic agent, reduced intimal thickening after endothelial injury in rats. In this study, to verify whether or not antiallergic agents inhibit intimal thickening, we investigated the effect of pemirolast on intimal thickening after endothelial injury and compared its effect with that of tranilast. Administration of two antiallergic agents, pemirolast (0.1, 1, and 10 mg/kg, p.o.) and tranilast (300 mg/kg, p.o., daily), was begun 2 days before endothelial injury and continued until the animals were killed. Endothelial injury in the rat femoral artery was induced by a photochemical reaction between localized irradiation by green light and intravenously administered rose bengal. To evaluate intimal hyperplasia, we measured the cross-sectional area of the intima 21 days after endothelial damage. Pemirolast at doses of 0.1, 1, and 10 mg/kg reduced the intimal area to 2.10 +/- 0.33, 1.36 +/- 0.19, and 1.35 +/- 0.18 (x0.01 mm2), respectively, and tranilast showed a tendency to reduce the intimal area, which was 1.86 +/- 0.35 x 0.01 mm2, compared with findings for controls (2.83 +/- 0.49 x 0.01 mm2). In rat A10 vascular smooth-muscle cells, we investigated the effects of antiallergic agents on migration by using a modified Boyden chamber assay and on proliferation by using the bromodeoxyuridine-incorporation assay. Two antiallergic agents inhibited in a concentration-dependent manner both migration and proliferation of smooth muscle cells stimulated by platelet-derived growth factor. These results suggest that antiallergic agents directly inhibit migration of smooth-muscle cells to the intima from the media and proliferation in the intima, and that pemirolast has more potent antihyperplastic action than does tranilast. Antiallergic agents may be effective in preventing restenosis after coronary angioplasty.

Animals↗

PubMed1997

Hyperpolarization and relaxation of canine vascular smooth muscle to vasoactive intestinal polypeptide.

This study was designed to determine the influence of the endothelium on the hyperpolarization induced by vasoactive intestinal polypeptide (VIP) in smooth muscle cells of canine blood vessels, and the potential contribution that these electrophysiologic changes may make to the relaxant effects of VIP. Membrane potential was measured in isolated canine coronary arteries and saphenous veins, using glass microelectrodes. Isometric force was recorded in a conventional organ chamber. All experiments were performed in the presence of indomethacin. VIP induced concentration-dependent and endothelium-independent hyperpolarization of the saphenous vein. This response was abolished by glibenclamide. VIP did not induce hyperpolarization of coronary arterial smooth muscle either in the presence or absence of the endothelium. VIP caused concentration-dependent and endothelium-independent relaxations of both arterial and venous rings. The relaxation of the saphenous vein to VIP was not influenced by glibenclamide. These data suggest that hyperpolarization of the cell membrane does not play a significant role in the relaxation of canine blood vessels to VIP.

Animals↗

PubMed1997

Clinical outcome of smoking-cessation trial of nicotine chewing gum evaluated by analysis of nicotine in hair.

The axial distribution of nicotine along the hair shafts was examined in 21 subjects enrolled in a placebo-controlled, double-blind trial of nicotine chewing gum (Nicorette) for validating their self-reported smoking behavior and their physicians' assessments. Hair samples obtained from the subjects once during the 3-month follow-up period (n = 10 for placebo and n = 11 for Nicorette ad libitum) were analyzed for the cm x cm distribution of nicotine along the hair shafts. Hair analysis results were compared with the monthly self-reports and with the plasma concentrations of thiocyanate (SCN-) measured at 1-month intervals. A gradual decrease in nicotine content along the hair shafts generally corresponded to the decrease in self-reported number of cigarettes smoked daily by the subjects who reported that they abstained from smoking or decreased the number of daily cigarettes in placebo and nicotine chewing gum groups. Because nicotine may dissociate slowly from hair follicle cells, nicotine in the hair did not mark a sudden decrease or cessation of smoking and, therefore, hair analysis tended to underestimate the real decrease of smoking. However, physician assessment seemed to depend solely on self-reporting because the time profile of changes in serum SCN- concentration did not correspond necessarily to the changes in the self-reported number of cigarettes used daily.

Adult↗

PubMed1997

In vitro comparison between mouse B16 and human melanoma cell lines of the expression of ICAM-1 induced by cytokines and/or hyperthermia.

The expression of intercellular adhesion molecule-1 (ICAM-1) in mouse B16 and human melanoma cell lines was investigated by indirect immunofluorescence using a FACScan analyzer. Mouse B16 melanoma cell lines (B16-F1 and F10) did not express ICAM-1 under ordinary culture conditions. Neither in vitro hyperthermia at 41 degrees C for 3 or 6 hr nor cytokines such as gamma interferon (IFN-gamma) or tumor necrosis factor alpha (TNF-alpha) induced ICAM-1 expression in B16 melanoma cell lines. A combination of IFN-gamma with TNF-alpha caused slight induction of ICAM-1 expression in the B16-F10 melanoma cell line. Hyperthermia at 41 degrees C for 3 hr in combination with the cytokines induced a slight expression of ICAM-1 in the B16-F1 melanoma cell line. Hyperthermia at 41 degrees C for 3 hr or 6 hr did not induce de novo ICAM-1 expression but hyperthermia at 43 degrees C for 6 hr caused rather suppression of the expression of ICAM-1 in the three human melanoma cell lines tested. In contrast, they showed a clear increase in the expression of ICAM-1 after treatment with either with IFN-gamma or TNF-alpha, and the expression was further augmented by a combination of the two cytokines. Treatment with cytokines in combination with hyperthermia at 41 degrees C or 43 degrees C for 3 hr did not augment the expression of ICAM-1 over that in cytokine-treated human melanoma cell lines, at normal temperatures. Thus, it is concluded that mouse B16-F1 and F10 melanoma cell lines are different from human melanoma cell lines in terms of induction of ICAM-1 expression by cytokines and/or hyperthermia.

Animals↗

PubMed1997

In-vivo microdialysis study of the distribution of cisplatin into brain tumour tissue after intracarotid infusion in rats with 9L malignant glioma.

Simultaneous brain microdialysis in tumour and non-tumour tissues has been used for kinetic determination of the local distribution of an anticancer agent, cisplatin, in rats. Rat brain was implanted with 9L malignant glioma and cisplatin (3.5 mg kg-1) was administered as a selective intracarotid infusion for 30 min to rats prepared for brain microdialysis. The amount of platinum in the dialysate collected from tumour and non-tumour brain tissues was determined by atomic absorption spectrophotometry, as representative of cisplatin. Total and free platinum concentrations in plasma were also measured. Free platinum is accumulated preferentially in the tumour tissue and the brain tumour distribution coefficient (the ratio of brain tumour platinum AUC to plasma free platinum AUC, where AUC is the area under the platinum concentration-time curve) was 0.69, although there was little distribution into normal brain tissue. Drug binding to plasma proteins was 65%. It is concluded that simultaneous microdialysis is an easy and available method for assessing in-vivo local pharmacokinetics and distribution of cisplatin in tumour and non-tumour tissues of the brain.

Animals↗

PubMed1997

Safety and pharmacokinetics of CS-834, a new oral carbapenem antibiotic, in healthy volunteers.

CS-834, (+)-[pivaloyloxymethyl (4R,5S,6S)-6-[(R)-1-hydroxyethyl]-4-methyl-7-oxo-3-[[(R)-5-oxopyrroli din-3-yl]thio]-1-azabicyclo[3.2.0]hept-2-ene-2-carboxylate], is an ester-type oral carbapenem prodrug, and an active metabolite is R-95867, which has antibacterial activity. CS-834 was administered orally to healthy male volunteers at single doses of 50, 100, 200, and 400 mg and at a multiple dose of 150 mg three times a day for 7 days to investigate its safety and pharmacokinetic profiles. Other studies were conducted to examine the effect of food intake on the bioavailability of CS-834 and also the effect of the coadministration of probenecid on the pharmacokinetics of CS-834. In the fasting state, the concentration of R-95867 in plasma reached maximum levels from 1.1 to 1.7 h after the oral administration of CS-834, followed by a monoexponential decrease. The maximum concentrations of R-95867 in serum (C[max]s) after the administration of CS-834 at doses of 50, 100, 200, and 400 mg were 0.51, 0.97, 1.59, and 2.51 microg/ml, respectively. The half-lives (t1/2s) were almost constant, approximately 0.7 h. The areas under the concentration-time curves (AUCs) were proportional to the doses, ranging from 50 to 400 mg x h/ml. The cumulative recoveries in urine were approximately 30 to 35% until 24 h after drug administration. The C(max), AUC, t1/2, and recovery in urine were not affected by food intake. Probenecid coadministration prolonged the t1/2, and it increased the C(max) and AUC for R-95867 by approximately 1.5- and 2.1-fold, respectively. The multiple-dose study showed no change in the pharmacokinetics from those for the single doses and no drug accumulation in the body. A mild transient soft stool was observed in one volunteer in the study with a single dose of 400 mg. In the multiple-dose study, mild transient soft stools were observed in six volunteers, one volunteer had mild transient diarrhea, and one volunteer had elevated serum glutamic oxalacetic transaminase and serum glutamic pyruvic transaminase levels (1.4- and 2.8-fold compared with the upper limits of normal, respectively). There were no other abnormal findings for objective symptoms or laboratory findings, including blood pressure, heart rate, electrocardiogram, body temperature, hematology, blood chemistry, and urinalysis.

Administration, Oral↗

PubMed1997

A flow cytometric analysis of the expression of adhesion molecules on human renal cell carcinoma cells with different metastatic potentials.

OBJECTIVES: We investigated the relationship between the metastatic potential and the surface expression of adhesion molecules on human renal cell carcinoma (HRCC) cells. METHODS: The metastatic potential was studied by the intravenous injection of cells from an HRCC cell line SN12C parent and its variants, SN12C-MM3, SN12C-clone2 and SN12C-clone8 into athymic Balb/c nude mice. The surface expression of adhesion molecules on these four HRCC cell lines was studied by a flow cytometric analysis. RESULTS: Of the four cell lines, SN12C-MM3 had the highest ability to produce pulmonary metastatic nodules. In contrast, the SN12C parent, SN12C-clone2 and SN12C-clone8 produced either few or no pulmonary metastatic nodules. A flow cytometric analysis revealed that SN12C-MM3 showed a strong expression of sialyl Lewis X (sialyl Le(x)) carbohydrate antigen and a slightly stronger expression of CD11a (LFA-1 alpha-chain) and CD54 (ICAM-1) compared with the other three cell lines. All cell lines expressed CD29 (beta 1-integrin) and CD44 to the same extent. CONCLUSION: Sialyl Le(x) is thought to be a ligand for the adhesion molecule called ELAM-1 (endothelial-leukocyte adhesion molecule-1, E-selectin) and mediates the interaction of leukocytes or tumor cells to endothelial cells, followed by the integrin-mediated adhesion. These data suggest that SN12C-MM3 cells may have more of a chance to adhere to endothelial cells in blood vessels and consequently shows a higher metastatic potential when injected intravenously in comparison to the other three lines.

Animals↗

PubMed1997

Expression of TGF-beta superfamily receptors in dental pulp.

Transforming growth factor-beta (TGF-beta) superfamily members and their cell-surface receptors may play inductive and/or regulatory roles in tooth development and repair. It will be important to identify the complete set of TGF-beta superfamily receptors, to examine their temporal and spatial localization during tooth development, and to elucidate the cascade of molecular events of tooth formation induced by the TGF-beta superfamily. In this report, we have cloned the cDNAs encoding potential receptors for TGF-beta superfamily members in rat incisor pulp and bovine adult pulp which are regarded as embryonic and adult pulp, respectively. We analyzed poly (A)+ RNA from rat incisor pulp and bovine adult pulp by reverse-transcriptase/polymerase chain-reaction (RT-PCR), using a degenerate primers corresponding to the most conserved amino acid sequences in the intracellular serine/threonine kinase of type I or type II like kinase-1 (ALK-1), ALK-2, ALK-3 (bone morphogenetic protein receptor type IA, BMPR-IA), ALK-4 (B1), ALK-5, ALK-6 (BMPR-IB), and BMPR-II (BMP type II receptor) was found to be in dental pulp. Northern blot analysis further detected TGF-beta type II receptor (T beta R-II) mRNA transcript in addition to the above-identified receptors. These results provide the first evidence of multiple type I and type II receptors for TGF-beta s, activins, and BMPs expressed in embryonic and adult pulp, implicating diverse function in tooth development and pulp tissue repair.

Activin Receptors↗

PubMed1997

Distribution of inhaled fluticasone propionate between human lung tissue and serum in vivo.

High retention of inhaled glucocorticoids in the airways means prolonged anti-inflammatory action and low delivery into the serum. The objective of this study was to investigate the retention in and distribution of inhaled fluticasone propionate (FP) between central and peripheral human lung tissue and serum in vivo. In 17 patients undergoing lung resection surgery, a single 1.0 mg dose of FP was inhaled at varying time-points (range 2.8-21.7 h) preoperatively. Peripheral and central lung tissue was obtained, and blood was drawn simultaneously. FP concentrations in central lung tissue were approximately three to four times higher than peripheral lung tissue concentrations, which in turn, exceeded those found in serum by 10 times. FP was detectable up to 21 and 16 h, respectively, after inhalation, with drug levels falling almost in parallel in peripheral lung tissue and in serum. The results of this study demonstrate that fluticasone propionate is retained in lung tissue for a long time. Serum concentrations after a single inhaled dose are low. Retention of high concentrations of fluticasone propionate in the airways may promote high topical anti-inflammatory activity.

Administration, Inhalation↗

PubMed1997

Preservation of functioning human thyroid "organoids" in the scid mouse. IV. In vivo selection of an intrathyroidal T cell receptor repertoire.

To study the in vivo influence of thyroid cells on the T cell receptor repertoire in human autoimmune thyroid disease, we mixed lymphocyte-free thyrocytes (approximately 1.2 x 10[6]) from patients with Graves' disease with autologous peripheral blood mononuclear cells (PBMC; approximately 1.5 x 10[6]) and transplanted this mixture sc into scid mice while suspended in a basement membrane gel (approximately 0.4 ml). Controls included mice that received either thyrocytes only or PBMC only. The resulting artificial mixed cell thyroid organoids were explanted after 5 weeks, and their T cell receptor repertoire was examined. Of a total of 63 organoids constructed, 60 were recovered (95.2%). Total RNA was extracted and then analyzed by reverse transcription-PCR primarily for human T cell receptor (hTcR) Vbeta gene expression using 21 hTcR Vbeta amplimers. A restricted pattern of hTcR Vbeta gene expression was found, with 6 Vbeta genes (Vbeta5, 6, 7, 8, 13.1, and 18) predominantly expressed [P < 0.05, by ANOVA on ranks and Student-Newman-Keul's (SNK) test]. PBMC and control organoids showed no preferential selection of particular hTcR V gene-expressing T cells. This reductionist, mixed cell, thyroid model reflected earlier observations in human and murine autoimmune thyroid diseases in which a bias in hTcR V gene family expression had been observed. The model permitted in vivo T cell selection and/or enrichment of potentially disease relevant human T cells.

Animals↗

PubMed1997

Detection of major T cell epitopes on human thyroid stimulating hormone receptor by overriding immune heterogeneity in patients with Graves' disease.

To examine the major immunogenic regions of the human TSH receptor (hTSHR), we examined 14 patients with Graves' disease and 14 healthy control subjects for their peripheral blood T cell proliferative responses to 29 synthetic peptides representing the entire ectodomain of the hTSHR (TSHR-ecd). By combining an analytical approach encompassing the grading of peptide-induced responses and nonparametric testing, we obtained evidence for highly significant differences (P = < 0.000001) in the patient group compared with minor differences in the control group (P = 0.045). To account for this difference, we identified four major T cell epitopes (amino acid 247-266, 202-221, 142-161, and 52-71), by multiple comparison analysis, in the patient group. Furthermore, we demonstrated by radiolabeled PCR that the responding T cells were clonally expanding. These findings demonstrate that despite likely differences in human leukocyte antigen type among patients with Graves' disease, several distinct hTSHR epitopes elicited significant responses in the immune system of patients with Graves' disease, and that such patients are most often poorly tolerant to particular epitopes of the TSH receptor ectodomain, The data support the notion of TSHR peptide antigens overriding human immune heterogeneity in patients with Graves' disease, and raise the possibility of applying analog peptide blockade to suppress T cell responsivity.

Adult↗

PubMed1997

Effects of astemizole on ventricular activation delay and RT intervals in a canine myocardial infarction model.

In order to clarify the arrhythmogenic effects of nonsedating antihistamines, we examined the effects of astemizole, a nonsedating antihistamine, on ventricular activation and RT intervals in a canine myocardial infarction model. Myocardial infarction was produced by two-stage ligation of the left anterior descending coronary artery in dogs. Seven days after ligation, bipolar electrodes were sutured on the ventricular surface of the infarcted and normal zones to apply an electrical stimulation or record the ventricular activation. An electrical stimulation with coupling intervals between 300 and 140 ms was applied on the ventricular surface of the normal zone during atrial pacing, and the ventricular activation delay was measured. The effect of astemizole on the RT interval was also determined during atrial pacing, sinus rhythm or after premature stimulation. The ventricular activation delay increased after astemizole at doses of 0.3 to 3 mg/kg in the infarcted and at 3 mg/kg in the normal zones, and the effect of astemizole was greater in the infarcted zone. Astemizole increased the RT interval in the normal zone to a greater extent at a long coupling interval. The increase in the RT interval was greater in the infarcted zone compared with that in the normal zone. In conclusion, astemizole increased the activation delay in the infarcted zone, probably through prolongation of the repolarization time, and its effect on the activation delay may be arrhythmogenic.

Animals↗