Biomedical subjects

M Toda

Publications and source records attributed to M Toda.

At least 73 records · Page 4Linked to original sources

PubMed1999

Suppression of glial tumor growth by expression of glial fibrillary acidic protein.

We examined the effect of expression of glial fibrillary acidic protein (GFAP) on the tumor growth of astrocytoma in vivo. When rat astrocytoma C6 cells were injected subcutaneously in athymic mice, the cells produced tumors that grew rapidly. The tumor growth of C6 cells transfected with GFAP cDNA was significantly reduced compared to that of control NeoC6 cells transfected only with the neomycin resistant gene. After implantation of C6 cells transfected with mutated GFAP cDNA at the phosphorylation sites, the tumor growth was suppressed similar to that of the wild GFAP transfectants. To determine whether the cell growth suppression by GFAP is specific for astroglial cells, we assessed the effect of GFAP on the cell growth of an L cell of fibroblast origin in vitro. By GFAP cDNA transfection, L cells showed morphological changes, but the cell growth was not reduced. These results suggest that GFAP is a critical regulator of the tumor growth of astrocytoma.

Amino Acid Sequence↗

PubMed1999

Effects of endothelial impairment by saponin on the responses to vasodilators and nitrergic nerve stimulation in isolated canine corpus cavernosum.

1. Responsiveness to EDRF-releasing substances and inhibitory nerve stimulation of canine isolated penile corpus cavernosum with and without saponin treatment were investigated. 2. Histological studies demonstrated that saponin did not detach endothelial cells from underlying tissues, but induced degenerative changes in the endothelial cells selectively. 3. In the cavernous strips contracted with phenylephrine, addition of acetylcholine, sodium nitroprusside, ATP and Ca2+ ionophore A23187 induced relaxations, but substance P and bradykinin did not change the muscle tone. 4. Acetylcholine-induced relaxation was significantly attenuated but not abolished by NG-nitro-L-arginine (L-NOARG). L-arginine restored the response inhibited by L-NOARG. The L-NOARG resistant relaxation was not influenced by 1H[1,2,4]oxadiazole[4,3-a]quinoxalin-1-one (ODQ) but was suppressed in the strips contracted with K+. Treatment with saponin abolished the relaxation elicited by acetylcholine and A23187 but did not influence the response to nitroprusside and ATP. The ATP-induced relaxation was attenuated by aminophylline. 5. Transmural electrical stimulation at 2-20 Hz produced endothelium-independent relaxations which were abolished by tetrodotoxin and L-NOARG but unaffected by treatment with saponin. In saponin-treated cavernous strips, the neurogenic relaxation was not affected by acetylcholine, physostigmine, atropine and vasoactive intestinal peptide (VIP) but was abolished by ODQ. 6. It is concluded that acetylcholine-induced relaxations are endothelium-dependent and mediated partly by NO and also by other substances from the endothelium. The endothelium-independent relaxation to ATP is likely to be mediated by P1 purinoceptors. The function of nitrergic nerve does not seem to be prejunctionally modulated by acetylcholine and VIP.

Acetylcholine↗

PubMed1999

Postoperative tetany in Graves disease: important role of vitamin D metabolites.

OBJECTIVE: To test the authors' hypothesis of the causal mechanism(s) of postoperative tetany in patients with Graves disease. SUMMARY BACKGROUND DATA: Previous studies by the authors suggested that postoperative tetany in patients with Graves disease occurs during the period of bone restoration and resulted from continuation of a calcium flux into bone concomitant with transient hypoparathyroidism induced by surgery. PATIENTS AND METHODS: A prospective study was carried out to investigate sequential changes in serum levels of intact parathyroid hormone (iPTH), calcium and other electrolytes, 25-hydroxyvitamin D (25OHD), 1,25-dihydroxyvitamin D (1,25(OH)2D), and bone metabolic markers in 109 consecutive patients with Graves disease who underwent subtotal thyroidectomy. RESULTS: Preoperative serum iPTH levels negatively correlated with ionized calcium levels and positively correlated with 1,25(OH)2D or 1,25(OH)2D/25OHD. After the operation, there was a significant decline in levels of ionized calcium, magnesium, and iPTH. Serum iPTH was not detected in 15 patients after surgery. Four of these 15 patients, and 1 patient whose iPTH level was below normal, developed tetany. Preoperative serum ionized calcium levels were significantly lower, and iPTH levels were higher, in the 5 patients with tetany than in the 11 patients who did not develop tetany despite undetectable iPTH levels. The tetany group had significantly lower serum 25OHD levels and higher 1,25(OH)2D levels, and had increased 1,25(OH)2D/25OHD as an index of the renal 25OHD-1-hydroxylase activity than those in the nontetany group. These results suggest that patients with a high serum level of iPTH as a result of low serum calcium levels (secondary hyperparathyroidism) are susceptible to tetany under conditions of hypoparathyroid function after surgery. CONCLUSIONS: Postoperative tetany occurs in patients with secondary hyperparathyroidism caused by a relative deficiency in calcium and vitamin D because of their increased demand for bone restoration after preoperative medical therapy concomitant with transient hypoparathyroidism after surgery. Calcium and vitamin D supplements may be recommended before and/or after surgery for patients in whom postoperative tetany is expected to develop.

Adolescent↗

PubMed1999

[Usefulness of bronchoscopy for the diagnosis of atypical pulmonary mycobacteriosis].

In 14 subjects whose chest radiographs showed abnormal shadows during the two years from January 1995 until December 1996, no definite diagnosis could be obtained because sputum, smears and cultures all gave negative results for mycobacteria. Bronchoscopy was therefore performed, revealing atypical mycobacteria in cultures of the bronchial washing fluid for mycobacteria, and the significance of bronchoscopic examinations in cases diagnosed an atypical pulmonary mycobacteriosis was investigated. Most of the subjects (9) were women. Nine subjects had been informed that they had abnormal chest shadows; five had subjective symptoms; bloody sputum, 3 and cough, 2. The characteristics of the shadows were as follows: in the plain radiographs, the main shadows had a mottled or granular appearance in the majority of the patients (9) and there were infiltrative shadows in 3 patients and nodular shadows in another 3. In computed tomograms, the shadows in the vicinity of the pleura appeared as micronodular conglomerates in 12 patients, in 11 of whom bronchiectasis was also present near the shadows. Alveolar infiltrative shadows were present in four cases, and a cavity was seen in only one. Smears of the bronchial washing fluid for mycobacteria were positive in 7 patients, and cultures of this fluid yielded at least 100 colonies in 8 of the 14 subjects for whom the results were positive. By culture, Mycobacterium avium complex (MAC) was identified in 13 patients, but eleven of these in whom the bronchial washing fluid was concurrently tested for MAC by the polymerase chain reaction, only four were MAC-positive. Transbronchial lung biopsies were performed in 11 cases, in which the histological findings of mycobacterial infections showed granuloma in four, and caseation in three. Bronchoscopy is making possible initial-stage diagnosis, which are normally difficult, among the recently growing number of cases of the bronchial form of atypical pulmonary mycobacteriosis and is also useful for reaching definite diagnosis in the early stage.

Adult↗

PubMed1999

Attenuated, replication-competent herpes simplex virus type 1 mutant G207: safety evaluation of intracerebral injection in nonhuman primates.

This study examined the safety of intracerebral inoculation of G207, an attenuated, replication-competent herpes simplex virus type 1 (HSV-1) recombinant, in nonhuman primates. Sixteen New World owl monkeys (Aotus nancymae [karyotype 1, formerly believed to be A. trivirgatus]), known for their exquisite susceptibility to HSV-1 infection, were evaluated. Thirteen underwent intracerebral inoculation with G207 at doses of 10(7) or 10(9) PFU, two were vehicle inoculated, and one served as an infected wild-type control and received 10(3) PFU of HSV-1 strain F. HSV-1 strain F caused rapid mortality and symptoms consistent with HSV encephalitis, including fever, hemiparesis, meningitis, and hemorrhage in the basal ganglia. One year after G207 inoculation, seven of the animals were alive and exhibited no evidence of clinical complications. Three deaths resulted from nonneurologic causes unrelated to HSV infection, and three animals were sacrificed for histopathologic examination. Two animals were reinoculated with G207 (10(7) PFU) at the same stereotactic coordinates 1 year after the initial G207 inoculation. These animals were alive and healthy 2 years after the second inoculation. Cerebral magnetic resonance imaging studies performed both before and after G207 inoculation failed to reveal radiographic evidence of HSV-related sequelae. Despite the lack of outwardly observable HSV pathology, measurable increases in serum anti-HSV titers were detected. Histopathological examination of multiple organ tissues found no evidence of HSV-induced histopathology or dissemination. We conclude that intracerebral inoculation of up to 10(9) PFU of G207, well above the efficacious dose in mouse tumor studies, is safe and therefore appropriate for human clinical trials.

Animals↗

PubMed1999

Insufficient effectiveness of 5-hydroxytryptamine-3 receptor antagonists due to oral morphine administration in patients with cisplatin-induced emesis.

PURPOSE: To compare the effect of 5-hydroxytryptamine-3 (5HT(3)) receptor antagonists in cancer patients receiving chemotherapy including cisplatin (CDDP), with or without sustained-release oral morphine (MS Contin; Shionogi Co, Osaka, Japan). PATIENTS AND METHODS: We retrospectively studied 58 lung cancer patients given chemotherapy including at least 50 mg/m(2) CDDP with 5-HT(3) receptor antagonists between January 1996 and December 1997. Number of vomiting episodes, average proportions of hospital-supplied meals consumed (0 to 100%, as an index of appetite), and nausea severity scores (0 to 2 points, subjective patient judgment) were compared between oral morphine-administered (+) and morphine-free (-) groups. RESULTS: Sixteen morphine(+) and 42 morphine(-) cases were used. In cases of acute emesis (within 24 hours after CDDP injection), morphine(+) and morphine(-) groups were significantly different in number of vomiting episodes (1.25 and 0.14, respectively; P <.0001), appetite (58.13% and 90.24%; P <.0001), and nausea severity scores (1.63 and 0.62; P <.0001). In delayed-emesis cases (24 to 120 hours after CDDP), these groups differed significantly in number of vomiting episodes (1.94 and 0.43, respectively; P =.0001), appetite (23.13% and 52.08%; P <.0001), and nausea severity (1.38 and 0.91; P =.009). There were no significant differences in sex, age, anticancer drugs concurrent with CDDP, CDDP dose, corticosteroid administration, clinical stage, or type of 5-HT(3) antagonist. CONCLUSIONS: These data suggest that morphine can markedly reduce the effectiveness of 5-HT(3) receptor antagonists in patients receiving chemotherapy that includes CDDP. These results require confirmation by reinvestigation of clinical data on the efficacy of 5-HT(3) receptor antagonists and by extensive prospective analyses.

Aged↗

PubMed1999

Neurogenic vasoconstriction as affected by cholinergic and nitroxidergic nerves in dog ciliary and ophthalmic arteries.

PURPOSE: To determine the involvement of noradrenergic and other vasoconstrictor nerves in the contraction of ocular arteries and the modification by cholinergic and nitroxidergic nerves of vasoconstrictor nerve function. METHODS: Changes in isometric tension were recorded in helical strips of the canine posterior ciliary and external ophthalmic arteries denuded of the endothelium, which were stimulated by transmurally applied electrical pulses (5 Hz). Vasoconstrictor mediators were analyzed by pharmacological antagonists, such as prazosin, alpha,beta-methylene ATP, a P2alpha-purinoceptor antagonist, and BIBP3226, a neuropeptide Y receptor antagonist. RESULTS: Transmural electrical stimulation produced contractions that were potentiated by N(G)-nitro-L-arginine (L-NA), a nitric oxide (NO) synthase inhibitor. The contraction was partially inhibited by prazosin and abolished by combined treatment with alpha,beta-methylene ATP but was not influenced by BIBP3226. Stimulation-induced contraction was attenuated by physostigmine and potentiated by atropine. Contractions induced by exogenous ATP were reversed to relaxations by alpha,beta-methylene ATP. In the strips treated with L-NA, prazosin, and alpha,beta-methylene ATP, the addition of L-arginine elicited relaxations by nerve stimulation. The ATP-induced relaxation was attenuated by aminophylline, whereas neurogenic relaxation was unaffected. CONCLUSIONS: Ciliary and ophthalmic arterial contractions by nerve stimulation are mediated by norepinephrine and ATP, which stimulate alpha1-adrenoceptor and P2X purinoceptor, respectively. ATP from the nerve is unlikely involved in vasodilatation. Acetylcholine derived from the nerve impairs the neurogenic contraction, possibly by interfering with the release of vasoconstrictor transmitters, and neurogenic NO also inhibits the contraction postjunctionally by physiological antagonism.

Acetylcholine↗

PubMed1998

Treatment of human breast cancer in a brain metastatic model by G207, a replication-competent multimutated herpes simplex virus 1.

We investigated the therapeutic efficacy of G207, a replication-competent multimutated herpes simplex virus type 1, for the treatment of human malignant mammary tumors metastatic to the brain. In vitro studies demonstrated that G207 efficiently destroyed three of four human malignant breast cancer cell lines. MDA-MB-435 was most susceptible and MDA-MB-231 was least susceptible to G207. In athymic mice harboring subcutaneous or intracerebral MDA-MB-435 cells, intraneoplastic inoculation of G207 caused growth inhibition and/or prolonged survival. In contrast, G207 had minimal effects on MDA-MB-231 subcutaneous tumor growth or survival in the intracerebral tumor model. The efficacy of G207 therapy in vivo correlated well with the susceptibility of the human cancer cells to G207 in vitro. Histological studies indicate that G207 replication is restricted to tumor cells in vivo and does not occur in the surrounding brain tissue. These results suggest that G207 shows particular promise for use as a novel antineoplastic agent for metastatic brain tumors and that in vitro testing may predict which tumors will be most responsive in vivo.

Adenocarcinoma↗

PubMed1998

In situ cancer vaccination: an IL-12 defective vector/replication-competent herpes simplex virus combination induces local and systemic antitumor activity.

Intratumoral inoculation of replication-competent, attenuated herpes simplex virus (HSV) mutants inhibits tumor growth by direct cytotoxic viral replication and induction of a tumor-specific immune response. To boost the antitumor response, we describe a defective HSV vector encoding IL-12 as an adjuvant to in situ vaccination by the replication-competent HSV helper virus. The defective HSV vector system consists of defective particles containing tandem repeats of the cytokine genes (p40 and p35) in combination with a HSV helper virus. Heterodimeric IL-12 was expressed and secreted after IL-12 defective vector infection of tumor cells. In a syngeneic, bilateral established tumor model with CT26 murine colon carcinoma, unilateral intratumoral inoculation with an IL-12 defective/replication-competent HSV vector combination significantly reduced tumor growth of the inoculated and noninoculated contralateral tumors. This antitumor effect was significantly greater than with a lacZ-defective/replication-competent HSV vector combination, which itself was significantly greater than the mock inoculation. Efficacy is associated with enhancement of tumor-specific CTL activity, including specificity against the CT26 immunodominant MHC class I restricted Ag AH1, and IFN-gamma production. There was no significant tumor growth inhibition after intratumoral inoculation of s.c. CT26 tumors in athymic mice. We conclude that this defective HSV vector system is an effective method for cytokine gene delivery to tumors in situ and IL-12 expression in tumors synergizes the antitumor activity mediated by the replication-competent HSV helper virus.

Animals↗

PubMed1998

Desmopressin-induced dog ciliary artery relaxation.

In isolated dog posterior ciliary arteries contracted with prostaglandin F2alpha, desmopressin (10(-10) to 10(-8) M), a vasopressin V2 receptor agonist, produced a concentration-related relaxation, which was reversed to a contraction by removal of the endothelium. Desmopressin was approximately 1/100 as potent as arginine vasopressin. Treatment with NG-nitro-L-arginine, a nitric oxide (NO) synthase inhibitor, reversed the desmopressin-induced relaxation to a contraction and the addition of L-arginine restored the relaxation. SR49059 ((2S)1-[(2 R3S)-(5-chloro-3-(2-chlorophenyl)-1-(3,4-methoxybenzene-s ulfony)-3-hydroxy-2,3-dihydro-1H-indole-2-carbonyl]-pyrrolidine-2-car boxamide), a selective vasopressin V1 receptor antagonist, suppressed the relaxation. In endothelium-denuded arteries, desmopressin-induced contractions were also inhibited by SR49059. It is concluded that desmopressin, although much less potent than vasopressin, relaxes ciliary arteries via a mediation of NO synthesized from L-arginine in the endothelium. Vasopressin V1-receptor Subtypes appear to be involved in the desmopressin-induced relaxation and contraction.

Animals↗

PubMed1998

Changing trends and prognoses for patients with papillary thyroid cancer.

OBJECTIVE: To analyze differences in the demographic backgrounds, and in treatments, prognosis, and risk factors of patients with papillary thyroid cancer operated on from 1965 to 1990, by dividing them into 3 chronological groups. DESIGN: Retrospective cohort study of 2423 patients with papillary thyroid cancer (tumor size, > or = 10 mm) who underwent curative surgery at the Noguchi Thyroid Clinic, Oita, Japan. SETTING: A center for the treatment of thyroid disease, at which about 1400 thyroid operations are performed per year. PATIENTS: There were 596 patients treated during from January 1, 1965, to December 31, 1973; 964 patients treated from January 1, 1974, to December 31, 1982; and 959 patients treated from January 1, 1983, to December 31, 1990. RESULTS: Of the 2519 patients treated, 96 were excluded from the study because they had undergone noncurative surgery. Therefore, the analyses are based on data for 2423 patients who underwent curative surgery. Three groups were defined as follows: group 1, underwent surgery during the period 1965-1973 (n = 577); group 2, underwent surgery during the period 1974-1982 (n = 924); and group 3, underwent surgery during the period 1983-1990 (n = 922). The mean age of the patients in group 1 was 42.4 years, in group 2, 45.0 years, and in group 3, 47.8 years. The mean tumor size was 30.4 mm, 26.5 mm, and 24.6 mm, respectively, for groups 1, 2, and 3. The 10- and 20-year disease-specific survival rates were significantly improved from group 1 (95.5% and 90.3%, respectively) to group 2 (97.8% and 93.9%, respectively), and the 10-year rate was significantly improved for group 3 (98.2%). In the multivariate analysis, age, sex, tumor size, and gross nodal metastasis were significant predictors of survival for group 1; however, only age and gross nodal metastasis were significant for group 3. CONCLUSIONS: Over time, papillary thyroid cancer has become diagnosed at an earlier stage, but the age of the patients at diagnosis is older. The disease-specific survival rate was significantly improved, mainly owing to earlier treatment, and the change in the risk factor profile for cancer mortality may be due to the changes in the demographic backgrounds and diagnostic and therapeutic modalities. These considerations derived from risk factor analysis should be considered for treating the patient and for the prediction of patient survival.

Adolescent↗

PubMed1998

Papillary thyroid carcinoma: modified radical neck dissection improves prognosis.

OBJECTIVE: To ascertain whether modified radical neck dissection offers a survival advantage for some subsets of patients with papillary cancer of the thyroid. DESIGN: A retrospective cohort study of 2966 patients curatively treated at the Noguchi Thyroid Clinic and Hospital Foundation, Oita, Japan, between 1946 and 1991. SETTING: A center for the treatment of thyroid disease, where about 1400 thyroid operations are performed per year. PATIENTS: Between 1946 and 1991, patients with papillary cancer whose primary tumor was 1 cm or larger and who were curatively treated were studied. Of the 2859 patients, 72.1% underwent modified radical neck dissection, 8.5% underwent partial node excision, and 19.4% underwent no node excision. RESULTS: A univariate analysis revealed a subset of patients who benefited from modified radical neck dissection. A multivariate analysis revealed that sex (P<.001), age at the time of the operation (P<.001), size of the primary tumor (P<.001), extrathyroidal invasion (P<.001), and the presence of nodal metastasis (P<.01) are significant risk factors. CONCLUSION: Patients with nodal metastasis, patients in whom the primary tumor invades beyond the thyroid capsule, and women older than 60 years can benefit from modified radical neck dissection.

Adult↗

PubMed1998

Oligodendroglioma of the "widespread" type in the spinal cord.

The authors present clinical, radiological, and pathological features of the "widespread" type of primary spinal oligodendroglioma arising in a 12-year-old boy. The initial symptoms were gait disturbance, hypesthesia of the lower trunk, and scoliosis. Gadolinium-enhanced magnetic resonance imaging revealed an intramedullary tumor with syringomyelia. The tumor spread rapidly in a "widespread" pattern within the spinal cord between C7 and T12. One year after surgery the patient had made a poor neurological recovery despite the two-stage tumor resection. Only five cases of widespread tumors, including our case, have been described with discussion of their clinical manifestations.

Child↗

PubMed1998

Chronic thyroiditis as a favorable prognostic factor in papillary thyroid carcinoma.

A subgroup of patients with papillary thyroid carcinoma (PTC) also has chronic thyroiditis (CT) as an associated disease of the thyroid. To assess the prognostic value of CT in patients with PTC, we reviewed the histological slides of 2225 patients with PTC who had undergone surgery between 1971 and 1992. Of the 2225 patients, 692 were excluded from the analysis because regional lymph nodes and/or nonneoplastic thyroid tissues were unavailable for histological assessment. The series included 281 patients with CT in nonneoplastic thyroid tissue and 1252 without CT. We performed statistical analyzes by the log-rank test and Cox's proportional-hazard method. Sixty-two (5.0%) of the 1252 patients without CT died of metastatic disease during the follow-up period and the relapse-free 10-year survival rate was 85%. By contrast, only 2 (<1.0%) of the 281 patients with CT died, and their relapse-free 10-year survival rate was 95%. The difference between patients with CT and those without CT in terms of relapse-free and overall survival was statistically significant (p < 0.0001). Risk factors for unfavorable outcome were age 45 years or more, absence of psammoma bodies, and absence of CT (p < 0.0001), followed by vascular invasion (p = 0.0007), male sex (p = 0.0013), and metastasis to regional lymph nodes (p = 0.047). Multivariate analysis indicated that all of these factors with the exception of gender were independent factors in the final model for overall survival. Chronic thyroiditis in the nonneoplastic thyroid of patients with PTC is a powerful prognostic factor for both relapse-free and overall survival.

Adult↗

PubMed1998

Immunologic self-tolerance maintained by CD25+CD4+ naturally anergic and suppressive T cells: induction of autoimmune disease by breaking their anergic/suppressive state.

Elimination of CD25+ T cells, which constitute 5-10% of peripheral CD4+ T cells in normal naive mice, leads to spontaneous development of various autoimmune diseases. These immunoregulatory CD25+CD4+ T cells are naturally unresponsive (anergic) in vitro to TCR stimulation, and, upon stimulation, suppress proliferation of CD25-CD4+ T cells and CD8+ T cells. The antigen concentration required for stimulating CD25+CD4+ T cells to exert suppression is much lower than that required for stimulating CD25-CD4+ T cells to proliferate. The suppression, which results in reduced IL-2 production by CD25-CD4+ T cells, is dependent on cellular interactions on antigen-presenting cells (and not mediated by far-reaching or long-lasting humoral factors or apoptosis-inducing signals) and antigen non-specific in its effector phase. Addition of high doses of IL-2 or anti-CD28 antibody to the in vitro T cell stimulation culture not only breaks the anergic state of CD25+CD4+ T cells, but also abrogates their suppressive activity simultaneously. Importantly, the anergic/suppressive state of CD25+CD4+ T cells appeared to be their basal default condition, since removal of IL-2 or anti-CD28 antibody from the culture milieu allows them to revert to the original anergic/suppressive state. Furthermore, transfer of such anergy/suppression-broken T cells from normal mice produces various autoimmune diseases in syngeneic athymic nude mice. These results taken together indicate that one aspect of immunologic self-tolerance is maintained by this unique CD25+CD4+ naturally anergic/suppressive T cell population and its functional abnormality directly leads to the development of autoimmune disease.

Animals↗

PubMed1998

Novel point mutations and allele loss at the RET locus in sporadic medullary thyroid carcinomas.

Germline mutations in the RET proto-oncogene have been shown to be the underlying cause of multiple endocrine neoplasia type 2 (MEN 2A and 2B) and familial medullary thyroid carcinoma (FMTC). Some cases of sporadic medullary thyroid carcinoma (sporadic MTC) are reported to have specific codon 918, 883 and 768 mutations of the RET gene in tumor tissues. We examined RET gene mutations in 40 Japanese cases who had previously undergone surgery for sporadic MTC. DNA extracted from formalin-fixed tumor tissues and corresponding normal thyroid tissues or peripheral blood leukocytes was analyzed for mutations of exon 10, 11, 13, 14 and 16 of the RET gene by DNA sequencing and by mutation-specific restriction enzyme analysis. Germline RET point mutations were found in six of 40 cases (15%), cysteine residues at codon 618 in two, codon 634 in three and valine residue at codon 804 in one, and were newly identified as heritable MTC. Of the remaining 34 sporadic MTC cases, four (12%) had tumor-specific RET point mutations. Two were found in exon 16; one case showed an ATG to ACG (Met to Thr) mutation at codon 918, and the other showed two point mutations, ATG to ACG (Met to Thr) at codon 918 and GCA to GTA (Ala to Val) at codon 919 with loss of the wild-type allele, suggesting that both alleles at the RET locus were altered. The other two were found in exon 13; one case showed a CCG to TCG (Pro to Ser) mutation at codon 766 and the other showed a silent mutation, GTC to GTT (Val) at codon 778 with loss of the wild-type allele. There was no association of sporadic mutations with recurrence or prognosis in patients with sporadic MTC. The low rate of somatic RET mutation at codon 918 in our sporadic MTC suggests that as yet unknown factors may be involved. Genetic alterations in both alleles may have an important role in small fraction of sporadic MTCs.

Adult↗

PubMed1998

Cholinergic nerve function in monkey ciliary arteries innervated by nitroxidergic nerve.

We sought to determine the control of ciliary arterial tone by neurogenic acetylcholine (ACh) acting directly on smooth muscle and in conjunction with vasodilator nerves. Isolated posterior ciliary arteries from monkeys responded to ACh (10(-8)-10(-5) M) with dose-related contractions, which were endothelium independent. The response was not affected by cyclooxygenase inhibitors but was abolished by atropine. Relaxations induced at 10(-4) M ACh in the atropine-treated arterial strips were abolished by hexamethonium and NG-nitro-L-arginine (L-NNA), and L-arginine (L-Arg) reversed the response suppressed by L-NNA. Similar results were also obtained on the nicotine (10(-4) M)-induced relaxation. Contractions due to transmural electrical stimulation in the endothelium-denuded strips treated with L-NNA were potentiated by physostigmine and depressed by atropine; the remaining contraction in the presence of atropine was abolished by prazosin. Relaxations associated with electrical stimulation, sensitive to tetrodotoxin, were abolished or reversed to contractions by L-NNA and restored by L-Arg. Stimulation-induced relaxation was attenuated by exogenous ACh and physostigmine and was potentiated by atropine. ACh did not affect the relaxation caused by nitric oxide (NO). Nerve fibers and bundles containing NADPH diaphorase and acetylcholinesterase were histologically demonstrated in the adventitia of ciliary arteries. We conclude that 1) endogenous and exogenous ACh contracts monkey ciliary arteries by acting on muscarinic receptors in smooth muscle cell membranes, 2) vasodilatation elicited by nerve stimulation with electrical pulses or nicotine is mediated by NO synthesized from L-Arg, 3) neurogenic ACh seems to interfere with the nitroxidergic nerve function by acting on prejunctional muscarinic receptors, and 4) high concentrations of ACh stimulate nicotinic receptors in vasodilator nerve terminals and promote the synthesis and/or release of NO.

Acetylcholine↗

PubMed1998

Increase of lipid hydroperoxides in liver mitochondria and inhibition of cytochrome oxidase by carbon tetrachloride intoxication in rats.

The cellular localization of lipid hydroperoxides was determined for the first time in mitochondria, microsomes and cytosol of rat liver using a specific method involving chemical derivatization and HPLC. Mitochondria contained the highest level of hydroperoxides. After 6h of intragastric administration of carbon tetrachloride (CCl4) to rats (2 ml/kg body weight), the concentration of lipid hydroperoxides increased significantly in liver mitochondria and cytochrome oxidase activity was inhibited to 35% of the control rats. The mitochondrial content of haem a decreased to 60% of the control at 12h of CCl4 administration. In vitro reaction of mitochondria with CCl4 caused inactivation of cytochrome oxidase. These observations suggested that cytochrome oxidase and haem a in mitochondria were targets of CCl4.

Animals↗