Biomedical subjects

C Nakamura

Publications and source records attributed to C Nakamura.

At least 91 records · Page 5Linked to original sources

PubMed1996

[Effect of human serum albumin on transport of drugs through human erythrocyte membranes].

The binding properties to human serum albumin (HSA) and the transport of drugs through human erythrocyte membranes were examined with benzoic acid or its twenty-five derivatives (o-, m-, or p-hydroxybenzoic acid, o-, m-, or p-aminobenzoic acid, o-, m-, or p-nitrobenzoic acid, o-, m-, or p-toluic acid, o-, m-, or p-fluorobenzoic acid, o-, m-, or p-chlorobenzoic acid, o-, m-, or p-bromobenzoic acid, aspirin, salicyluric acid, alpha-resorcylic acid and gamma-resorcylic acid) and with glycosides (arbutin, salicin, glycyrrhizin and four p-nitrophenylglycosides) or their aglycons (hydroquinone, saligenin, glycyrretinic acid and p-nitrophenol). The drugs having hydroxyl group and amino group to o-site and those having nitro group, methyl group and halogen group to m- or p-site showed higher affinity with HSA and the plasma hindered the permeability of these drugs. The glycosides bind to each site (1, 2, and 3) of HSA more weakly than do their aglycons and they were difficult for plasma to hinder membrane permeation. The binding constants of each drug to HSA (Kb-site 1, Kb-site 2, Kb-site 3 and Kb-total) and the inhibition ratio (IR) related to the partition coefficient (P): Kb-site 1 (M-1) = 2.1479 x 10(3).square root of P - 5.2824.P + 2.0985 x 10(3) (R = 0.9371), Kb-site 2 (M-1) = 4.3741 x 10(3).square root of P - 15.2068.P + 6.5660 x 10(3) (R = 0.6788), Kb-site 3 (M-1) = 2.2176 x 10(4).log P + 1.2022 x 10(4) (R = 0.5227), Kb-total (M-1) = 1.0214 x 10(4).square root of P - 33.3721.P + 1.6919 x 10(4) (R = 0.7413), IR (%) = 19.885.log P + 17.916 (R = 0.8605). IR obtained from predictive equations (IR = 17.837.log P - 13.286. log Kb-site 1 + 0.175.square root of Kb-site 2 + 0.074.square root of K b-site 3 + 37.355, R = 0.9642, F = 71.4937***, ***; p < 0.001) by multiple regression analysis was compatible with experimental IR.

Benzoates↗

PubMed1996

Role of the sympathetic nervous system in the nocturnal fall in blood pressure.

To evaluate mechanisms responsible for differences between patients showing a nocturnal fall in blood pressure ("dippers") and those showing no such fall in blood pressure ("nondippers"), we performed 24-hour (h) ambulatory blood pressure monitoring in 25 patients with untreated essential hypertension who were 37-49 years of age (16 men and 9 women). The diagnosis of essential hypertension was based on the patients' history, physical examination, routine laboratory tests, and intravenous pyelography. Blood pressure was measured by sphygmomanometer and by noninvasive ambulatory monitoring for 24 h. Exercise was performed on a supine bicycle ergometer. The initial workload was 50 W and was increased progressively by 25 W at 3-min intervals. Plasma and urinary norepinephrine levels were measured by high-performance liquid chromatography. Dippers were defined as patients with a difference of > 10 mmHg in the systolic BP or > 5 mmHg in the diastolic BP between daytime and nighttime. Eleven patients were dippers and 14 patients were nondippers. There was a positive correlation between the nocturnal fall in blood pressure and the rise in blood pressure during exercise (r = 0.54, p < 0.01), and the increase during exercise was greater in dippers than in nondippers. There was also a significant positive correlation between the urinary norepinephrine level and the fall in blood pressure at night (r = 0.75, p < 0.01). A significant increase in plasma norepinephrine during exercise was found in dippers, as compared with nondippers. These results suggest that in patients with hypertension a nocturnal fall in blood pressure is closely related to the blood-pressure response to exercise, and that the attenuation of sympathetic nervous activity might play an important role in the nocturnal decrease in blood pressure.

Adult↗

PubMed1996

Protective effect of N-benzoyl-beta-alanine against cisplatin nephrotoxicity in rats.

Prophylactic effects of N-benzoyl-beta-alanine (betamipron, BP), one of a series of N-acyl amino acids, were examined against cisplatin-induced nephrotoxicity. Male Wistar rats were injected i.p. with 6 mg/kg of cisplatin combined with an i.p. BP dose given at various times and various doses. Rats were sacrificed 5 days after cisplatin injection to weigh the kidney and liver, and to determine blood urea nitrogen (BUN) and serum creatinine (serum Cr) levels. Preliminary results suggest that treatment with BP is an effective means of protection against cisplatin-induced nephrotoxicity. Combination with BP reduced the weight loss following treatment with cisplatin. The ratios of the kidney and liver weights to the body weight in the animals treated with cisplatin followed later with BP are significantly different (p < 0.05) from those in the animals that received only cisplatin. The BUN and serum Cr levels in the animals treated with cisplatin followed from -1 to 4 hr, and from -4 to 4 hr later with 250 mg/kg BP dose and followed 1 hr later with from 250 to 1000 mg/kg, and from 250 to 2000 mg/kg BP doses differed significantly (p < 0.05) from those in the animals that received only cisplatin. Histological analysis of the kidneys confirmed the protective effect of BP.

Alanine↗

PubMed1996

Effects of postnatal cocaine on differentiation of the rat corpus callosum.

We investigated the effects of cocaine on the development of the corpus callosum. Pregnant Wistar strain rats (Thirteenth day of gestation) were used in this study. On the day following birth, litters were culled to 8 pups (4 males and 4 females), and rats were assigned to either a control or drug treatment group. From postnatal day 1 (P1, at birth = P0) to P5, cocaine (50 mg/kg) was subcutaneously injected to the cocaine-treated pups, and saline in the same volume to the control pups. Animals were sacrificed in 110 days and a mid-sagittal section of the callosum was obtained. From this section the morphometric measurement of the corpus callosum was performed. In the control group the rat corpus callosum has a sex difference with the male corpus callosum being larger than the female's. But this sex difference disappeared in the cocaine group. This was attributed to the fact that cocaine-treated male rats indicated a significant reduction of callosal area. These findings suggest that the early postnatal cocaine can abolish the sexual differentiation of the corpus callosum.

Animals↗

PubMed1995

An iron-regulated gene, magA, encoding an iron transport protein of Magnetospirillum sp. strain AMB-1.

Magnetospirillum sp. AMB-1 is a freshwater magnetic bacterium which synthesizes intracellular particles of magnetite (Fe3O4). A genomic DNA fragment required for synthesis of magnetic particles was previously isolated from a nonmagnetic transposon Tn5 mutant. We have determined the complete nucleotide sequence of this fragment. The 2975-base pair region contains two putative open reading frames. One open reading frame, designated magA, encodes a polypeptide which is homologous to the cation efflux proteins, the Escherichia coli potassium ion-translocating protein, KefC, and the putative Na+/H(+)-antiporter, NapA, from Enterococcus hirae. Northern hybridization demonstrated that the magA mRNA transcript is 1.3 kilobases in size, corresponding to the size of the magA gene. A functional promoter was located upstream from the magA gene, and the transcription in AMB-1 was regulated by environmental iron concentration. Vesicles isolated from E. coli in which the MagA protein was expressed exhibited iron accumulation ability. We consider that the MagA protein is an iron transport involved in the synthesis of magnetic particles in AMB-1.

Amino Acid Sequence↗

PubMed1995

Overexpression of mitochondrial genes in alloplasmic common wheat with a cytoplasm of wheatgrass (Agropyron trichophorum) showing depressed vigor and male sterility.

An alloplasmic hybrid (nucleus-cytoplasm hybrid) of common wheat (Triticum aestivum) with a cytoplasm of wheatgrass (Agropyron trichophorum) shows highly depressed vigor and complete male sterility. The presence of one short-arm telocentric homeologous group 1 chromosome (telosome) of the cytoplasm donor, however, restores normal vigor and male fertility of the hybrid. To study role(s) of the telosome on vigor/fertility restoration, mitochondrial genome organization and gene expression were compared among seedlings of the alloplasmic line showing depressed vigor, the corresponding restored line having a pair of the telosomes, and a euplasmic nuclear donor as control. No differences were detected in the mitochondrial genome structure between the depressed line and the restored line. Northern blot analysis using ten mitochondrial genes as probes showed no differences in transcript size and number between the depressed and restored lines, although clear differences were found in size of the major transcripts of two genes (cob and orf25) between the alloplasmic lines and the euplasmic control. Steady-state transcript levels were higher in the depressed line than in the other lines for all the mitochondrial genes analyzed including rrn18&5 when the same amount of mitochondrial RNA was loaded. The amount of rrn18&5 transcript in the total cellular RNA, however, did not differ among the lines. Run-on transcription analysis demonstrated markedly elevated transcriptional activities of all the mitochondrial genes analyzed in the depressed line based on unit amount of mitochondrial DNA, RNA and protein. The presence of Agropyron telosomes apparently normalized the level of mitochondrial transcription. These observations suggest either direct or indirect association of the observed mitochondrial gene overexpression with the depressed vigor and male sterility of the alloplasmic hybrid.

Amanitins↗

PubMed1995

Iron-regulated expression and membrane localization of the magA protein in Magnetospirillum sp. strain AMB-1.

The magA gene from Magnetospirillum sp. strain AMB-1 is required for the synthesis of bacterial magnetic particles (BMPs). This gene has been cloned, sequenced and found to encode a protein which is homologous to the Escherichia coli potassium efflux membrane-binding protein, KefC. By using the firefly luciferase gene (luc) cloned downstream of the magA promoter, the effect of iron on regulation of magA expression was investigated, and transcription of magA was found to be enhanced by low concentrations of iron. Intracellular localization of the MagA protein was studied using magA-luc fusion proteins. The luc gene was cloned downstream of the magA hydrophilic C-terminal domain. Detection of luciferase activity in the cytoplasm, cell membrane, and magnetic particle membrane subcellular fractions confirmed that the MagA fusion protein was localized in the cell membrane. The fusion protein was also detected on the surface of the lipid bilayer covering the magnetic particles. These results suggest that MagA is a membrane-bound protein, the expression of which is enhanced at low iron concentrations.

Amino Acid Sequence↗

PubMed1995

[Valve repair or valvulectomy without replacement for infective endocarditis: a report of 11 cases].

Recently advances in early diagnosis of infective endocarditis (IE) by echocardiography provide for IE as a target disorder for valve repair. Valvulectomy without replacement might be still better operation of choice for some cases of intractable right-sided endocarditis. For our experience in 11 cases of valve repair or valvulectomy without replacement for IE, actuarial survival and reoperation-free rate at 6.8 years of mean follow-up after surgery was 81.8% and 90.9%. Persistent infection and intraoperative evaluation of the residual regurgitation was the point for postoperative management after these procedures. Although an elaborative valve repair should be applied for right-sided endocarditis, total pulmonary valvulectomy or regional tricuspid valvulectomy without prosthesis was available for destructive endocarditis.

Adolescent↗

PubMed1995

Autopsy cases among patients with mental disorders: an unusual case of asphyxia caused by the iron roller of a garbage truck.

A case of asphyxia of a young man suffering from "Identity Disorder" as delineated by the DSM-III-R (American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders revised in 1987) is reported. The patient jumped into the drum of a garbage truck and the iron roller in the drum asphyxiated him by compression. In addition to the presentation of this rare category of the DSM-III-R disorders as an autopsy case and an unusual means of asphyxia, we briefly reviewed other autopsy cases of the patients with mental disorders who died in Japan between 1988 and 1992.

Accidental Falls↗

PubMed1995

[A case report of infective endocarditis complicated with Klippel-Trenaunay-Weber syndrome].

We reported an experience of successful aortic valve replacement due to active infective endocarditis complicated with Klippel-Trenaunay-Weber (KTW) syndrome which was characterized by limb hypertrophy, hemangioma, arteriovenous fistula and varicose veins. A 27-year-old man was admitted to our hospital because of severe dyspnea and high grade fever. Echocardiogram revealed severe aortic regurgitation and destruction of aortic valve due to active infective endocarditis. We performed aortic valve replacement and patch closure of annular abscess. As to vascular malformation of lower limb including arteriovenous fistula and varicose veins, surgical treatment was not undergone to avoid postoperative limb dysfunction. Although the origin of infective endocarditis was uncertain, the patient had peripheral vascular malformations. It was postulated that valvular endocardial injury might be occurred by cardiac volume overload due to arteriovenous fistula. The patients with KTW syndrome should be followed under careful observation since infective endocarditis may be one of the complications of the syndrome.

Adult↗

PubMed1994

Spontaneous rupture of the descending aorta through atherosclerotic plaque: report of a case.

Spontaneous rupture of the thoracic descending aorta is rare, and uniformly fatal without surgery. We report herein the case of a man in whom such a rupture was successfully treated with emergency surgery. We believe that the rupture in this patient was most likely associated with perforation through an atherosclerotic plaque of the descending aorta and was induced by sudden hypertension.

Aged↗

PubMed1994

Effect of temocapril on haemodynamic and humoral responses to exercise in patients with mild essential hypertension.

1. This study was carried out to evaluate the effect of temocapril on haemodynamic and humoral responses to exercise in nine patients with mild essential hypertension (WHO stages I and II). 2. After a 4-week placebo period, temocapril was administered at a dose of 1.0 mg once daily for 2-4 weeks. Graded submaximal bicycle ergometer exercise was performed before and after temocapril treatment, and the changes in arterial blood pressure, heart rate, cardiac output (CO), and systemic vascular resistance (SVR) were evaluated. In addition, the plasma norepinephrine (NE) level was determined both at rest and peak exercise before and after temocapril treatment. 3. Both the systolic and diastolic blood pressure were reduced at rest and during exercise by temocapril treatment. No significant change in the resting heart rate and CO was observed, and the exercise-induced increase of these parameters was also not affected by temocapril. In contrast, the resting SVR was significantly decreased by temocapril, although the exercise SVR was similar during both temocapril and placebo treatment. 4. Although there was no significant change in the plasma NE level with temocapril treatment, the exercise-induced increase of plasma NE was significantly suppressed by temocapril. 5. These results indicate that temocapril reduces the blood pressure without causing any significant changes in the heart rate and CO at rest, and that it does not produce any changes in the haemodynamic response to exercise.

Adult↗

PubMed1994

[Reoperations for complications after mechanical valve replacement].

Among 310 patients with mechanical valve replacement, 24 patients required reoperations for three types of complications; 12 disc immobilizations on 10 patients, 9 prosthetic valve endocarditis (PVE) on 8 patients and 8 perivalvular leakage or aortic pseudoaneurysm on 7 patients. Long-term survival was 71 percent for PVE and leakage, and 20 percent for emergency surgery of disc immobilization with mean follow up of 67 months. We suggest a few compromised patients with healed fungal endocarditis might show various types of prosthetic valve complications such as tissue ingrowth, late perivalvular leakage or pseudoaneurysmal formation.

Adolescent↗

PubMed1994

[Localized cardiac tamponade after aortic valve replacement: a case report].

We report a case of localized cardiac tamponade after aortic valve replacement. A 56-year-old man had an aortic valve replacement for his aortic valve steno-insufficiency. At 3-postoperative day, severe hypotension occurred, causing acute renal failure. There were no cardiomegaly, high central venous pressure, nor echo-free space. A mass shadow, appearing on chest X-ray at 37-postoperative day, was diagnosed as a localized tamponade by means of a computed tomography and a radioangiography at 38 postoperative day. After the spontaneous drainage of old bloody effusion from the partially opened wound in mid-line, his cardiac and renal failure improved rapidly. When the hematoma is localized, computed tomography is most diagnostic while conventional echo-cardiography often fails to show echo-free spaces.

Aortic Valve↗

PubMed1993

Stereoselective analysis of the disposition of tosufloxacin enantiomers in man.

The pharmacokinetics of tosufloxacin enantiomers after oral administration of racemic tosufloxacin were examined in healthy volunteers. Only small differences were observed in time to peak concentration (2.6 +/- 0.3 [mean +/- SEM] h for (+)-tosulfoxacin vs 2.4 +/- 0.2 h for (-)-tosufloxacin), elimination half-life (3.61 +/- 0.24 h vs 3.49 +/- 0.23 h), and area under the curve (2.78 +/- 0.19 h.micrograms/ml vs 2.87 +/- 0.19 h.micrograms/ml); however, peak concentration (0.40 +/- 0.03 microgram/ml vs 0.44 +/- 0.03 microgram/ml), renal clearance (226 +/- 10 ml/min vs 202 +/- 10 ml/min), and urinary recovery (35.4 +/- 2.2% vs 32.4 +/- 1.9%) differed significantly between enantiomers.

Administration, Oral↗

PubMed1993

[Post operative embolism and left atrial enlargement in the old-aged ASD (atrial septal defect) patients].

As the operation risk of ASD is little today, the unexpected postoperative complication such as embolism is a miserable concern. We experienced two cases of embolism, which were cerebral infarction, in old-aged patients after ASD correction. It has been reported that low cardiac function, atrial fibrillation and foreign body in the left atrium should be risk factors of the embolism after ASD correction. However, blood stasis in the left atrium due to its enlargement may be an essential risk factor of the embolism. Accordingly we evaluated the left atrial volume in 87 ASD patients without complicated cardiac disorder. There was a significant correlation between the age (X) and left atrial volume index (Y). (Y = 16.5 + 1.1X, r = 0.668, p < 0.001). Left atrial volume index in our two cases of cerebral infarction indicated 171.7, 190.8 ml/m2 respectively. The former case had sinus rhythm and its defect was directly closed, and the latter had atrial fibrillation and its defect was closed with teflon patch. In addition pulmonary artery pressure and cardiothoracic ratio correlated with left atrial volume index significantly. Although some investigators reported that pulmonary hypertension and cardiomegaly were the risk factors of embolism, the left atrial enlargement by aging was thought to be the main risk factor. Thus, we concluded that anticoagulant therapy was necessary for the ASD patients with marked left atrial enlargement.

Aged↗

PubMed1993

[Palliative management of left atrioventricular valve atresia with normal aortic valve].

We present three cases of the left atrioventricular valve atresia (LAVVA) with normal aortic valve. All cases showed [S,D,D] and had concordant AV connection. First case had two functional ventricles with multiple VSD and ventriculo-arterial connection was normal. Interatrial communication was maintained through ASD and the infant underwent pulmonary arterial banding (PAB). Four years later, the patient underwent Blalock-Hanlon (B-H) procedure for an inadequate ASD. Second case showed the univentricular heart of right ventricle with double outlet. In this case, PFO was restrictive and the infant underwent B-H procedure. Ten days after initial palliation, patient underwent PAB. Third case showed the univentricular heart of left ventricle and transposed great arteries. This patient had also the coarctation of the aorta. B-H procedure, PAB and subclavian flap aortoplasty were performed simultaneously by bilateral thoracotomy. All patients have done well, with normal growth and development at the time of their last outpatient evaluation at 10 year, 9 months and 9 months after surgery respectively.

Aortic Valve↗

PubMed1993

[A blind point of vent catheter: air aspiration].

We experienced a case of saphenous vein air embolism after coronary artery bypass graft, in which case we used vent catheter kept in the left atrium. Though it was considered that air bubbles were never aspirated through vent catheter, we speculated that the origin of air bubbles must be the vent catheter. And we made an experiment on the motion of air in the vent catheter using a model of left heart composed with soft reserver (atrium) and pulsatile pump (ventricle). When the pulsatile pump was arrest, the air bubbles were never aspirated from the vent catheter to the soft reserver even if we vented with strong negative pressure. But, when the pulsatile pump was in motion and the left atrium was vented with some negative pressure, some leaks of air bubbles were recognized. So we must pay much more attention to the degree of venting when the heart is in motion. Sometimes we use overpressure safety valve composed with vent catheter, but measured left atrial pressure showed that decreased left atrial pressure was only 2 mmHg. So its use should be restricted in the patients with good ventricular function.

Catheterization, Central Venous↗