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Biomedical subjects

N Tamura

Publications and source records attributed to N Tamura.

At least 199 records · Page 11Linked to original sources
PubMed1994

[Retroviral infection as a putative pathogen for sarcoidosis].

Sarcoidosis is a granulomatous disorder of unknown etiology. Accumulated data suggest that one or several exogenous or altered self antigens participate in producing pathophysiological change in sarcoidosis. Recently, analysis of retroviruses such as HTLV-1 and HIV-1 revealed that these viruses would produce autoimmune disease like symptoms including interstitial lung disease like pulmonary manifestation. We hypothesized novel type retrovirus or retrovirus related antigens might be a putative pathogen for sarcoidosis. Syncytial cell formation or cytopathic effect was observed in 6 of 24 patients (25%) after coculture of sarcoid BALF cells with U937 cells. Five of 18 culture supernatant showed moderate reverse transcriptase activity. Expression of clone 4-1 env protein, one of the endogenous retroviral elements, was also observed in alveolar macrophages of sarcoidosis. These data encourages the further investigation of retrovirus as the pathogen of sarcoidosis.

Adult↗
PubMed1994

[Idiopathic pure sudomotor failure].

We describe three cases of acquired generalized anhidrosis without other autonomic and somatic nervous dysfunctions (idiopathic pure sudomotor failure; IPSF) and a review of the literature was made in regard to the clinical features of this disease. Patient 1. A 17-year-old man was found to be severely anhidrotic and intolerant to heart loading, which produced an immediate sharp pain over the entire body surface in April, 1989. Sudden and spontaneous remission occurred in July, 1990, but relapsed six months later. He was admitted to our hospital seeking for therapy in April, 1991. There were no abnormal findings on physical and neurological examinations except for anhidrosis. Patient 2. A 14-year-old boy was admitted to our hospital in March 1991 with complaints of intolerance to heart loading and sharp pain, which had begun ten months before admission. Physical and neurological examinations revealed no abnormal findings except for anhidrosis. Patient 3. A 21-year-old woman suddenly experienced a burning sensation in the whole body in 19th, February, 1991, which was followed by severe pain. She was admitted to our hospital in the next day. Apart from sensory impairment of glove and stocking type, neurological examination revealed no abnormal findings. Reflex sweating to pilocarpine was absent in all three cases, suggesting abnormality in the postganglionic sudomotor nerves or cholinergic receptors. Skin biopsy was performed in one patient (patient 1), and revealed no abnormalities of the sweat glands and ducts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Biotransformation of pravastatin sodium (I). Mechanisms of enzymic transformation and epimerization of an allylic hydroxy group of pravastatin sodium.

One of the major metabolites, R-416(3'alpha-OH), of pravastatin sodium(PV, 6'beta-OH), and a minor metabolite, R-418 (6'alpha-OH), were produced in rat liver cytosol in the presence of adenosine 3'-phosphate 5'-phosphosulfate as a cofactor. The reactions were inhibited by the inhibitors for sulfotransferases, and 18OH was introduced to the 3'alpha- and 6'alpha-positions of R-416 and R-418, respectively, by incubation with H2 18O. These results strongly suggested that PV was metabolically activated by sulfation at the 6'beta-hydroxy group by sulfotransferases, followed by nucleophilic attack of hydroxy anions at the 3'alpha- or 6'alpha-position, to give R-416 or R-418, respectively.

Animals↗
PubMed1993

Identification of the T cell surface signal-transducing glycoprotein sgp-60 as CD48, a counter-receptor for mouse CD2.

We recently showed that CD48 is the major counter-receptor for CD2 in the murine system. To examine whether sgp-60, which has been proposed as the murine homologue of human LFA-3, is another ligand for mouse CD2, we performed the characterization of sgp-60 by using mouse CD2-human IgG chimeric protein (mCD2Rg) and anti-mouse monoclonal antibodies (mAb). Anti-sgp-60 mAb 5-8A10, as well as anti-mouse CD48 mAb HM48-1 completely inhibited the binding of mCD2Rg at the ligand site. 5-8A10 immunoprecipitated the same molecule as that recognized by HM48-1 and reacted with mouse CD48 cDNA-transfected chinese hamster ovary cells, indicating that sgp-60, recognized by 5-8A10, is identical to mouse CD48. The epitope recognized by 5-8A10 was different from that recognized by HM48-1 and OX78, suggesting that the different T cell activating property of these anti-mouse CD48 mAb depends on the epitopes they recognize. The identification of sgp-60 as CD48 further suggests a role of CD48 in regulating T cell activation.

Animals↗
PubMed1993

Tissue factor production by cultured rat glomerular epithelial cells.

It is well known that fibrin deposition in Bowman's space in association with crescent formation may play an important role in progressive glomerular injury in crescentic glomerulonephritis. Recent reports describe the presence of a procoagulant activity (PCA) in the glomeruli and its increased expression in human and experimental nephritis. The cells that synthesize PCA have not yet been identified. We attempted to determine if glomerular epithelial cells (GEC), one of the prominent cell populations in the crescent, can produce PCA. The PCA of cultured rat GEC was measured by clotting and amidolytic assays. The cultured GEC yielded PCA with the characteristics of a tissue factor, and this PCA was stimulated by interleukin 1, tumour necrosis factor-alpha, and lipopolysaccharide. We concluded that GEC produce tissue-factor-like PCA and thereby may contribute to fibrin deposition, which, along with macrophage or monocyte infiltration, leads to crescent formation in crescentic glomerulonephritis.

Animals↗
PubMed1993

Lipopolysaccharide isolated from a new O-antigenic form (O13) of Vibrio parahaemolyticus.

The chemical properties of a lipopolysaccharide (LPS) isolated from a new O-antigenic form (O13) of Vibrio parahaemolyticus were investigated. The LPS contained glucose, galactose, L-glycero-D-manno-heptose and glucosamine. 2-Keto-3-deoxy-octonate (KDO) was not detected in the LPS by the periodate-thiobarbituric acid test (Weissbach's reaction) under conventional hydrolysis conditions. Instead, phosphorylated KDO (X1 and X2) was found in its strong-acid hydrolysate. This sugar composition was identical to that of V. parahaemolyticus O3, O5 and O11 LPS, indicating that, based on the sugar composition, O13 LPS belongs to Chemotype III to which O3, O5 and O11 belong. In addition, structural study demonstrated the presence of KDO 4-phosphate in its inner-core region.

Carbohydrates↗
PubMed1993

Optically active antifungal azoles. I. Synthesis and antifungal activity of (2R,3R)-2-(2,4-difluorophenyl)-3-mercapto-1-(1H-1,2,4-triazol-1-yl)-2-b utanol and its stereoisomers.

(2R,3R)-2-(2,4-Difluorophenyl)-3-mercapto-1-(1H-1,2,4-triazol-1-yl )-2-butano l [(2R,3R)-7] and its stereoisomers [(2S,3R)-, (2S,3S)- and (2R,3S)-7] were prepared from the optically active oxiranes 6 by a newly developed ring-opening reaction and evaluated for antifungal activity. The thiol (2R,3R)-7 showed extremely potent antifungal activity in vitro and in vivo. The optically active oxirane (2R,3S)-6, a useful intermediate for the synthesis of sulfur-containing antifungal azoles 5, was synthesized from methyl (R)-lactate [(R)-8] via eight steps in a stereocontrolled manner. The key step in the synthesis is the Grignard reaction of an amide derivative [(R)-12a] of (R)-lactic acid with 2,4-difluorophenyl-magnesium bromide (13).

Animals↗
PubMed1993

Optically active antifungal azoles. II. Synthesis and antifungal activity of polysulfide derivatives of (2R,3R)-2-(2,4-difluorophenyl)-3-mercapto-1-(1H- 1,2,4-triazol-1-yl)-2-butanol.

In an effort to find potent antifungal agents, a variety of optically active triazole derivatives with a polysulfide structure, 3, 4 and 5, were prepared and evaluated for antifungal activity against Candida albicans in vitro and in vivo. The symmetrical polysulfides 3 (m = 2-4) were obtained by an oxidative coupling reaction of (2R,3R)-2-(2,4-difluorophenyl)-3-mercapto-1-(1H-1,2,4-triazol-1-yl )-2-butanol (1) or by the treatment of its thiocarbonate derivative 8 with potassium tert-butoxide. The unsymmetrical disulfides 5 were synthesized by the reaction of the thiol 1 with Bunte salts 11 or the thiosulfinate 12 or by the reaction of the thiocarbonate 8 with various thiols 13. All of these polysulfides showed potent antifungal activity against candidosis in mice.

Animals↗
PubMed1993

[Pharmacological profile of F-0401, a novel dihydropyridine derivative. (1) Mechanisms of action].

F-0401 is a novel dihydropyridine (DHP) derivative with potent vasodilative and anti-aggregatory actions. In the present study, we examined the mechanisms of the actions of F-0401 and obtained the following findings: F-0401 suppressed [3H]nitrendipine binding to rat heart membrane (Ki value: 2.2 x 10(-7) M). CaCl2-induced contractions of rabbit aorta and guinea pig taenia coli were inhibited by F-0401 (pA2 values: 7.7 and 6.6). These results indicated that F-0401 had calcium antagonistic activity slightly less potent than that of the other DHP derivatives. In addition, F-0401 significantly inhibited the activity of thromboxane (TX) A2 synthetase (IC50 value: 2.5 x 10(-7) M) and [3H]PAF binding to rabbit platelets (Ki value: 1.4 x 10(-8) M). The other DHP derivatives tested did not affect TXA2 synthetic activity, and the PAF antagonism of the other derivatives were less than that of F-0401. Neither F-0401 nor the other DHP derivatives inhibited cAMP- or cGMP-dependent phosphodiesterase activity. These results revealed that F-0401 has calcium antagonistic, anti-PAF and TXA2 synthetase inhibitory actions in the same dose ranges.

Animals↗
PubMed1993

Disseminated intravascular coagulation in a patient with systemic lupus erythematosus with lupus anticoagulant.

A 19-year-old female patient with systemic lupus erythematosus (SLE) who had lupus anticoagulant (LA) and concurrently developed disseminated intravascular coagulation (DIC) during an exacerbation of "central nervous system (CNS) lupus". Since no other indications or causes for DIC could be demonstrated, she was treated with prednisolone and anticoagulants, which rapidly alleviated her DIC condition as well as "CNS lupus". Although abnormalities of coagulation are frequently reported in SLE patients, DIC rarely occurs in patients with SLE without associated complications. A review of the pathogenesis of DIC in patients with SLE is discussed.

Adolescent↗
PubMed1993

[Pseudohyperkalemia in myotonic dystrophy].

Serum electrolytes were measured in 14 patients with myotonic dystrophy and 25 healthy controls. The serum level of sodium was 144.8 +/- 3.2 (mean +/- SD) mEq/l in myotonic dystrophy and 142.0 +/- 1.9 mEq/l in the controls, and the level of potassium was 4.6 +/- 0.4 mEq/l and 4.0 +/- 0.3 mEq/l, respectively. Both electrolyte levels were significantly higher in the disease (p < 0.01, p < 0.001). Blood samples obtained from 5 patients and 5 controls were allowed to stand at room temperature, and serum electrolyte levels were repeatedly measured at 5, 30, 60, 120 minutes after blood collection. The measurement of serum potassium in myotonic dystrophy was elevated in the parallel with standing-time. The serum potassium was significantly higher in the patients than in the controls at 60 and 120 minutes standing. These results suggest that myotonic dystrophy has red blood cell membrane abnormality which allows potassium to leak.

Adult↗
PubMed1993

Reactive arthritis induced by Vibrio parahaemolyticus.

We describe a case of reactive arthritis after Vibrio parahaemolyticus infection. V. parahaemolyticus is the principal bacteria involved in the causation of foodborne gastroenterocolitis outbreaks in Japan. Several bacteria have been recognized as being involved in the development of reactive arthritis and this is the first report of reactive arthritis induced by V. parahaemolyticus.

Adult↗
PubMed1993

[A case of paraneoplastic autonomic and sensorimotor neuropathy with dysfunction in the afferent limb of baroreflex arc].

A 65-year-old man visited our hospital with complaints of tingling sensation in the distal parts of his extremities and dysuria, which first appeared 2 months before admission. He had no abnormal findings on physical examination. Neurological examination revealed sensory impairment of glove and stocking type, mild motor weakness and muscular atrophy in the proximal parts of arms and legs, and absent tendon reflexes in knees and ankles. Fasciculation was observed on his shoulders and upper extremities, and myokymia on the abdominal wall and bilateral calves. He had hyponatremia, which was proved to be caused by SIADH. Anti-acetylcholine receptor antibody, anti-GM1 ganglioside antibody and anti-galactocerebroside antibody were detected in the serum. Chest X-ray showed mass shadows in the mediastinum, which were confirmed as malignant thymoma by needle biopsy. Orthostatic hypotension, neurogenic bladder and anhidrosis were observed by the autonomic function tests. Lesions responsible for orthostatic hypotension and SIADH were suspected in the afferent fibers from baroreceptors, since an reactive increase of plasma arginine vasopressin to orthostatic hypotension was blunted and reflex hypertension in the cold pressor test was well-preserved, while overshoot in Valsalva's maneuver was absent. It is important that afferent baroreceptor dysfunction may be associated with paraneoplastic neurological syndrome, since lesions in acute autonomic neuropathy are usually in the efferent fibers.

Afferent Pathways↗
PubMed1993

[A prospective study on necessary and sufficient retinal photocoagulation for diabetic retinopathy].

The present studies were performed to determine whether slight photocoagulation was better than heavy photocoagulation for the early stage of progressive proliferative diabetic retinopathy (PDR). The authors selected 17 patients who had bilateral PDR of equal severity (BI or BII stage according to Fukuda's classification). In every case, we randomly performed heavy photocoagulation (laser burns were 1142 +/- 179) to one eye and slight photocoagulation (405 +/- 166) to the other eye. More than 6 months after the last photocoagulation, the effects of these treatments were compared in both eyes by fundus pictures, visual acuity and posterior vitreous fluorophotometric values. The results of judgement by fundus pictures and by vitreous fluorophotometric values were in perfect agreement. Eight cases (47%) in whom eyes received slight photocoagulation showed result better than the other eye. Two cases (12%) which received heavy photocoagulation were better than the other eye. Seven cases (41%) showed the same level of severity. No significant differences were found between slight and heavy photocoagulation.

Adult↗
PubMed1992

Organization, structure, chromosomal assignment, and expression of the gene encoding the human endothelin-A receptor.

We have isolated and characterized the gene for the human endothelin-A receptor. Southern blot analyses demonstrated a single copy gene for the receptor. The gene spans more than 40 kilobases and contains eight exons and seven introns. Intron 1 exists in the 5'-noncoding region, and introns 2-7 occur in the coding region. The locations of introns 2-7 exist before or after the regions encoding the membrane-spanning domains. The transcription start site, determined by primer extension experiments, is 502 base pairs upstream of the methionine initiation codon. The 5'-flanking region lacks a typical TATA box but contains a potential SP-1-binding site 27 base pairs upstream of the transcription start site. Using human-rodent somatic hybrid cell DNA, the gene was assigned to human chromosome 4. Northern blot analyses revealed a 4.3-kilobase mRNA in a wide variety of human tissues, at the highest level in the aorta and at a substantial level in the cultured human mesangial cells. This is the first report of cloning of a gene for a member of the endothelin receptor family. The present study should give a clue to the discovery of possible disorders of the endothelin-A receptor, as well as facilitate the elucidation of the mechanisms by which the gene expression is regulated.

Amino Acid Sequence↗