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Biomedical subjects

K Tanabe

Publications and source records attributed to K Tanabe.

At least 199 records · Page 11Linked to original sources
PubMed1999

Allelic diversity and antibody recognition of Plasmodium falciparum merozoite surface protein 1 during hypoendemic malaria transmission in the Brazilian amazon region.

The polymorphic merozoite surface protein (MSP-1) of Plasmodium falciparum is a major asexual blood-stage malaria vaccine candidate. The impact of allelic diversity on recognition of MSP-1 during the immune response remains to be investigated in areas of hypoendemicity such as the Brazilian Amazon region. In this study, PCR was used to type variable regions, blocks 2, 4, and 10, of the msp-1 gene and to characterize major gene types (unique combinations of allelic types in variable blocks) in P. falciparum isolates collected across the Amazon basin over a period of 12 years. Twelve of the 24 possible gene types were found among 181 isolates, and 68 (38%) of them had more than one gene type. Temporal, but not spatial, variation was found in the distribution of MSP-1 gene types in the Amazon. Interestingly, some gene types occurred more frequently than expected from random assortment of allelic types in different blocks, as previously found in other areas of endemicity. We also compared the antibody recognition of polymorphic (block 2), dimorphic (block 6), and conserved (block 3) regions of MSP-1 in Amazonian malaria patients and clinically immune Africans, using a panel of recombinant peptides. Results were summarized as follows. (i) All blocks were targeted by naturally acquired cytophilic antibodies of the subclasses IgG1 and IgG3, but the balance between IgG1 and IgG3 depended on the subjects' cumulative exposure to malaria. (ii) The balance between IgG1 and IgG3 subclasses and the duration of antibody responses differed in relation to distinct MSP-1 peptides. (iii) Antibody responses to variable blocks 2 and 6 were predominantly type specific, but variant-specific antibodies that target isolate-specific repetitive motifs within block 2 were more frequent in Amazonian patients than in previously studied African populations.

Adolescent↗
PubMed1999

Magnesium dynamics and sympathetic nervous system activity in patients with chronic heart failure.

This study was undertaken in patients with heart failure to investigate the relation between plasma norepinephrine (NE) concentration and Mg dynamics. The study subjects comprised 16 patients with chronic heart failure (mean age 64.9+/-10.0 years). Cardiopulmonary exercise testing was performed on all patients, and anaerobic threshold (AT), peak oxygen uptake (peak VO2) and peak exercise time were measured. Resting and peak values of plasma NE concentration and serum and erythrocyte magnesium concentration were also measured. The results were as follows: the serum Mg concentration was increased significantly immediately after exercise (p<0.01), and the erythrocyte Mg concentration showed a tendency to decrease (p<0.1). The resting plasma NE level was inversely correlated with AT (p<0.05, r=-0.57), peak VO2 (p<0.05, r=-0.55) and peak exercise time (p<0.01, r=-0.62). When the plasma NE concentration at rest was analyzed in 2 groups of patients, ie, those with higher than average and those with lower than average concentrations, the resting erythrocyte Mg concentration was significantly lower in the high-NE group (2.2+/-0.3 mg/dl) than in the low-NE group (2.7+/-0.5 mg/dl) (p<0.05). The data indicate that patients with chronic heart failure associated with high NE levels at rest who showed low exercise tolerance have intracellular hypomagnesemia, which may be caused by Mg migration from intracellular to extracellular spaces.

Adult↗
PubMed1999

Exercise-induced changes in plasma atrial natriuretic peptide and brain natriuretic peptide concentrations in healthy subjects with chronic sleep deprivation.

Recent observations have shown that plasma levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) correlate with cardiac function or prognosis in heart failure patients. However, relatively little is known about changes in their plasma concentration during commonly occurring physiological states such as fatigue. Therefore, this study was designed to examine the physiological changes of plasma ANP and BNP concentrations using a chronic sleep-deprivation model. Bicycle ergometer cardiopulmonary exercise tests were performed in 10 healthy volunteers (mean age: 22.7 years). Blood samples for measuring ANP and BNP were drawn during the resting state and immediately after each exercise test. Cardiac output (CO) was measured during the exercise test by the impedance method. The study conditions were designed as follows: (A) a day following a period of normal sleep (control state) and (B) a day preceded by 1 month during which sleep lasted <60% of normal (chronic sleep-deprived state). Results were as follows. (1) Peak oxygen uptake and peak CO decreased during the sleep-deprived state compared with the control state. (2) There was no difference between peak heart rates measured during exercise under the 2 conditions. (3) Plasma ANP concentration during exercise increased significantly during the control state, whereas only a tendency toward increase was observed during the sleep-deprived state. (4) Plasma BNP concentration during exercise tended to increase in the control state compared with the resting state, whereas there was no difference in plasma BNP between after exercise and resting state in the sleep-deprived state. These results indicate that changes of ANP or BNP induced by exercise tended to be decreased by chronic sleep deprivation.

Adult↗
PubMed1999

Differential diagnosis of left ventricular mural thrombi by myocardial contrast echocardiography: a preliminary study.

Two-dimensional echocardiography has become the procedure of choice to diagnose left ventricular mural thrombi. However, small or flat thrombi may be difficult to distinguish from myocardium. The spatial distribution of the ventricular myocardial blood flow can be imaged with myocardial contrast echocardiography (MCE). The authors presumed that the absence of arterial supply to a fresh thrombus may allow MCE to distinguish between thrombus and myocardium. In the 2 cases presented here, MCE was performed with the same technique as that used for the purpose of visualization of myocardial perfusion; as a result, an apical mural thrombus, indistinct from myocardium before MCE, was visualized as a contrast defect during imaging. Conversely, myocardium that mimicked a thrombus was imaged by MCE as a contrast-opacified area. These findings suggest that MCE after reperfusion therapy is useful to distinguish mural thrombi from myocardium.

Aged↗
PubMed1999

Effects of exercise training on the recovery of the autonomic nervous system and exercise capacity after acute myocardial infarction.

This study investigated the effects of aerobic exercise training on the early phase of the recovery process following acute myocardial infarction (AMI) in terms of the autonomic nervous system, cardiac function and exercise capacity. Twenty-eight patients in the first week after the onset of AMI were assigned randomly to either a training group or a control group. The training group performed aerobic exercise for 2 weeks. Cardiopulmonary exercise testing was performed 3 times during the 3 months after the onset. Heart rate variability, plasma norepinephrine (NE) levels, and cardiac index (CI) during exercise were measured. In the training group, plasma NE level and deltaCI (peak CI-rest CI) were significantly improved from 1 to 3 weeks after the onset, and the high frequency of heart rate variability and peak oxygen uptake were significantly increased up to 3 months after the onset. In the control group, the plasma NE level and the deltaCI during the 1-3 weeks post-AMI, the high frequency of heart rate variability and the peak oxygen uptake showed a tendency to improve up to 3 months after the onset. These results indicate that sympathetic nervous activity improves soon after the onset of AMI, in conjunction with improvement in cardiac function, and that this improvement is not affected by exercise training. In contrast, the recovery of parasympathetic nervous activity requires a longer period, along with the recovery of exercise capacity, which is facilitated by even short-term aerobic exercise training.

Aged↗
PubMed1999

Autotransplantation and stent implantation for bilateral renal artery fibromuscular dysplasia.

A 36-yr-old male was found to have renovascular hypertension due to an occluded right renal artery and 70% stenosis in the left renal artery, caused by fibromuscular dysplasia. The right kidney was supplied by collateral blood flow, and secreted more renin than the left kidney. Two differential therapeutic approaches were taken: autotransplantation for the right kidney and percutaneous transluminal renal angioplasty followed by stent implantation for the left. The renovascular hypertension was treated with these therapies, preserving renal function in this patient.

Adult↗
PubMed1999

A probable relationship between an endogenous digitalis-like substance and concentric cardiac hypertrophy in primary aldosteronism.

A 44-year-old woman was admitted to our hospital due to severe hypertension. An electrocardiogram (ECG) and an echocardiogram showed severe left ventricular hypertrophy. Her plasma aldosterone level was elevated. Magnetic resonance imaging revealed a small mass in the right adrenal gland. Before removal of the tumor, plasma endogenous digitalis-like substance (EDLS) levels were elevated. After removal of the tumor, EDLS levels quickly returned to the normal level. A series of echocardiograms and ECGs over a 6- year period after removal of the tumor showed marked regression of cardiac hypertrophy. These findings suggest that EDLS may be closely related to the development of concentric cardiac hypertrophy in primary aldosteronism.

Adrenal Gland Neoplasms↗
PubMed1999

[Renal angiomyolipoma with a tumor thrombus extending into the right atrium--a case report].

We present a case of spontaneous rupture of renal angiomyolipoma with a tumor thrombus extending from the right renal vein and inferior vena cava to the right atrium. A 41-year-old woman, previously in good health, was referred to our hospital with right flank pain. Computed tomography showed fat densities in both tumor and thrombus. Other imaging examinations also demonstrated a large right renal mass (18 cm in diameter), a long tumor thrombus (13 cm in length) and a small left renal tumor (1.5 cm in diameter). Right nephrectomy and en-bloc removal of the intra caval and intracardiac tumor thrombus were performed on cardiopulmonary bypass. It was pathologically diagnosed as an angiomyolipoma without tuberous sclerosis. At present, three years after surgery the patient is doing well, showing neither metastasis nor increase of the left renal angiomyolipoma. To our knowledge, our case seems to be the 3rd case report of renal angiomyolipoma with a tumor thrombus extending to the right atrium. We conclude that renal angiomyolipoma even with an intra cardiac tumor thrombus can be resected safely and successfully.

Adult↗
PubMed1999

EM2487, a novel anti-HIV-1 antibiotic, produced by Streptomyces sp. Mer-2487: taxonomy, fermentation, biological properties, isolation and structure elucidation.

For the purpose of discovering novel agents that inhibit HIV-1 replication at the transcriptional level, we have established cell lines reflecting the HIV-1 long terminal repeat-driven gene expression. Using these cell lines, we have screened approximately 10,000 microorganism products and found that the culture supernatant of Streptomyces sp. Mer-2487 suppresses the HIV-1 Tat-induced gene expression without affecting the basal or tumor necrosis factor-alpha-induced transcription. The purified active component has a unique structure, as shown in Fig. 1. This compound has an inhibitory effect on HIV-1 replication in chronically infected cells as well as acutely infected cells, suggesting that the inhibition occurs at a postintegration step of HIV-1 proviral DNA in the HIV-1 replication cycle.

Anti-Bacterial Agents↗
PubMed1999

DX-9065a, an orally active factor Xa inhibitor, does not facilitate haemorrhage induced by tail transection or gastric ulcer at the effective doses in rat thrombosis model.

DX-9065a is an antithrombin III (AT III)-independent and selective inhibitor of activated blood coagulation factor X (FXa). We evaluated the effects of DX-9065a and warfarin on bleeding time and blood loss in rat tail transection model and on blood loss in hydrochloride (HCl)-induced rat gastrointestinal haemorrhage model. The blood loss was determined by measuring the haemoglobin content in saline immersed with transected tail or hematin chloride content in the gaster after HCl administration. DX-9065a or warfarin was administered orally at 1 h or 15-21 h before the haemorrhagic stimuli, respectively. The dose required for 50% inhibition of thrombus formation (ID50) was 21 mg/kg for DX-9065a and 0.75 mg/kg for warfarin in a copper wire-inserted arteriovenous (AV) shunt model. In contrast to DX-9065a (10 or 30 mg/kg), warfarin (0.75 mg/kg) significantly prolonged the bleeding time. In rat tail transection model, the blood loss for the control group was 102+/-41 microl at 20 min after the transection. While warfarin (0.75 mg/kg) facilitated the blood loss about 5 times as much as the control, DX-9065a (10 or 30 mg/kg) did not. In rat gastrointestinal model, the blood loss for the control group was 15.9+/-5.6 microl at 15 min after HCl administration. In contrast to DX-9065a (10 or 30 mg/kg), warfarin (0.75 mg/kg) increased the blood loss about twice as much as the control. Thus, compared with warfarin, DX-9065a only increased bleeding time or blood loss to a minor extent in the doses tested. These observations suggest that direct inhibition of FXa could be preferable to warfarin in the suppression of thrombosis without haemorrhagic complications.

Administration, Oral↗
PubMed1999

Clinical significance of perfusion imaging of the left atrial wall and structures in its cavity by contrast echocardiography.

This study examined whether myocardial contrast echocardiography (MCE) can visualize left atrial appendage myocardial perfusion using transesophageal echocardiography (TEE) with intracoronary injection of sonicated albumin. We also evaluated blood flow into normal structures (i.e. muscular trabeculae) and abnormal masses (i.e. fresh thrombi and myxomas) within the left atrium by MCE. TEE images were obtained with a biplane or multiplane 5 MHz transducer in 16 patients without significant coronary artery occlusive disease. Left atrial appendage myocardium was divided into 4 segments in both the transverse and longitudinal planes, and contrast opacification of each segment during MCE was visually evaluated by 2 independent observers. Visual assessment of contrast opacification of prominent muscular trabeculae within the left atrial appendage (6 patients), and of left atrial or left atrial appendage thrombi (4 patients), was also performed. The ratio of background-subtracted peak videointensity from muscular trabeculae or thrombi versus left atrial appendage myocardium was determined as corrected peak videointensity. In 3 patients with myxomas, contrast opacification of the tumor was visually assessed. Ninety-six segments of left atrial appendage myocardium were visually analyzed. Contrast opacification of the left atrial appendage myocardium was identified in 92 of 96 segments (96%, 95% confidence interval 0.90-0.98) by Observer 1 and in 91 of 96 segments (95%, 95% confidence interval 0.88-0.98) by Observer 2. MCE also enhanced the imaging of left atrial appendage muscular trabeculae, but not of left atrial or left atrial appendage thrombi. Corrected peak videointensity from thrombi was significantly lower than that from muscular trabeculae (0.15 +/- 0.11 vs 0.95 +/- 0.18, p < 0.05). All myxomas were distinctly opacified by MCE. Transesophageal MCE with intracoronary injection of sonicated albumin can image left atrial appendage myocardial perfusion. MCE allows the evaluation of blood flow into normal structures and abnormal masses within the left atrium.

Adult↗
PubMed1999

Peritubular capillary deposition of C4d complement fragment in ABO-incompatible renal transplantation with humoral rejection.

In ABO-incompatible renal transplantation complement activation may be related to antibody-associated humoral rejection. However, immune deposits within the vasculature have been infrequently demonstrated in biopsy specimens. Whether deposition of complement fragment C4d is correlated with graft outcome and pathological findings (as measured by the severity of antibody-associated humoral rejection) is investigated in this study. Nineteen ABO-incompatible and 9 ABO-compatible renal graft biopsy specimens were selected. Four out of 19 ABO-incompatible patients lost their grafts within 1 yr. Ten out of 19 ABO-incompatible and just 1 out of 9 ABO-compatible patients, had prominent C4d deposition in peritubular capillaries. ABO-incompatible patients with predominant C4d deposition showed few tubulitis, accumulation of polymorphonuclear cells and thrombosis in peritubular and glomerular capillaries. The severity of the humoral rejection was correlated to C4d deposition in peritubular capillaries. Three out of four graft losses in ABO-incompatible renal transplantation showed severe humoral rejection and profuse deposition of C4d complement fragments in peritubular capillaries. Immunosuppression therapy was discontinued in the 4th patient, who lost his graft because of his lethal intestinal bleeding. C4d deposition in peritubular capillaries would be helpful for differential diagnosis between humoral rejection and drug-induced nephrotoxicity, and may serve as a sensitive marker of ABO-incompatible humoral rejection for patients with unsatisfactory (no glomeruli) biopsy specimens.

ABO Blood-Group System↗
PubMed1999

Clinical and histological analysis of acute tacrolimus (TAC) nephrotoxicity in renal allografts.

UNLABELLED: Tacrolimus (TAC) is an effective primary immunosuppressive agent in kidney transplantation. Acute nephrotoxicity due to TAC in kidney transplant patients is either similar to, or significantly more frequent than that of cyclosporin A (CsA). In this study we describe the clinico-morphologic characteristics of acute TAC nephrotoxicity in kidney transplant recipients. PATIENTS AND METHODS: We studied retrospectively the clinical courses of 67 patients who underwent kidney transplantation under TAC immunosuppression at Tokyo Women's Medical University between July 1990 and January 1997. We compared the recipient's characteristics with and without acute TAC nephrotoxicity. We also studied retrospectively the clinico-morphologic profiles of the acute TAC nephrotoxicity with 16 kidney transplant recipients under TAC immunosuppression, who were diagnosed with acute TAC nephrotoxicity by allograft biopsies between January 1996 and January 1997. RESULTS: There were no significant differences between acute TAC nephrotoxicity and non-nephrotoxicity groups about age, sex, donor source, age of donor, the proportion of ABO incompatible and the number of human leukocyte antigen (HLA) mismatches. Of 27 acute TAC nephrotoxicity recipients, 7 patients (26%) had moderate-to-severe grade arteriosclerosis in their allograft arteries. The onset of TAC nephrotoxicity occurred 8-69 days post-operatively. The baseline creatinine level was 1.92 mg/dL (range 0.4-5.1 mg/dL) and rose by 38.4% (range 0-84.6) during episodes of nephrotoxicity. The mean peak of the whole blood TAC trough level during the toxic episodes was 32.5 ng/mL (range 21.2-58.5 ng/mL). The rise in creatinine level preceded the highest TAC level in 10 cases. A mean reduction in TAC dosage of 18.9% (range 0-50% led to a fall of 17.2% (range 0-43%) in serum creatinine levels. The moderate-to-severe arteriosclerosis in allograft arteries was seen in 5 (31%) patients. CONCLUSION: The high trough level of the whole blood TAC and the existence of moderate-to-severe arteriosclerosis in allograft arteries have the potential of causing TAC nephrotoxicities. A reduction of TAC dosage may be effective in improving allograft functions.

Adult↗
PubMed1998

Long-term renal function in on-heart-beating donor kidney transplantation: a single-center experience.

BACKGROUND: One of the most serious problems facing major transplant programs is the severe shortage of organs. Expansion of the donor pool to include nontraditional donors, such as non-heart-beating donors (NHBDs), would considerably expand the availability of organs. METHODS: Between 1983 and 1996, we performed a total of 125 non-heart-beating cadaveric renal transplantations under cyclosporine-based or tacrolimus-based immunosuppression. Thirty-nine recipients were females and 86 were males. Total ischemic time (TIT) and warm ischemic time (WIT) were an average of 761+/-347 min (322-2027 min) and 7.4+/-13.1 min (0-45 min), respectively. RESULTS: Of the 125 transplanted kidneys from NHBDs, 98 (78.4%) developed delayed graft function (DGF), which lasted a mean of 16+/-21 days (range 3-37 days). One hundred and eight patients (86.4%) were off dialysis by the time of discharge. Of the 125 grafts, 11 (8.8%) were primary nonfunction. The average of the nadir of serum creatinine levels, which was evaluated using 108 patients who were off dialysis by the time of discharge, was 1.4+/-0.5 mg/dl. The lowest creatinine levels (nadir) were under 2.0 mg/dl in 98 (78.4%) of the 125 patients. Acute rejection occurred in 64 (51.2%) of the 125 recipients. Patient survival rates were 90% at 5 years and 88% at 10 years. Graft survival rates were 65% at 5 years and 46% at 10 years. We tried to find the risk factors that affected graft survival. We examined the various possible risk factors, including harvesting condition (controlled versus uncontrolled), HLA-AB mismatches, HLA-DR mismatches, graft weight, donor age and sex, recipient age and sex, posttransplant DGF, acute rejection, WIT, and TIT. However, no significant risk factor was identified except acute rejection. We tried to discover the risk factors that caused primary nonfunction. Possible risk factors, including donor age, TIT, WIT, graft weight, and harvesting condition were compared, but no significant risk factor was identified. Long-term renal function was evaluated by serum creatinine levels. Serum creatinine levels at 1, 5, and 10 years were 1.76+/-0.7 mg/dl, 1.7+/-0.96 mg/dl, and 1.53-/+0.6 mg/dl, respectively. CONCLUSIONS: In conclusion, our data demonstrated that the procurement of kidneys from NHBDs leads to acceptable long-term graft survival and renal function, despite a high incidence of DGF.

Adult↗
PubMed1998

Rho-associated kinase phosphorylates desmin, the myogenic intermediate filament protein, at unique amino-terminal sites.

We obtained evidence that Rho-associated kinase (Rho-kinase) phosphorylates desmin, the myogenic intermediate filament protein, with approximately 2 mol phosphate per mole of desmin in vitro. Desmin phosphorylated by Rho-kinase lost the potential to form 10-nm filaments. Thr-16, Thr-75, and Thr-76 on desmin proved to be the major phosphorylation sites for Rho-kinase. All these sites are located within the head domain and are different from the reported phosphorylation sites of protein kinase. A, protein kinase C, and cdc2 kinase. We are entertaining the notion that Rho-kinase may regulate filament structures of desmin by site-specific phosphorylation.

Amino Acid Sequence↗
PubMed1998

Involvement of caspase-like proteinases in apoptosis of neuronal PC12 cells and primary cultured microglia induced by 6-hydroxydopamine.

Activation of proteolytic enzymes, including the caspase family of proteinases, is a feature characteristic of the apoptotic program. In the present study, we examined a potential role of intracellular proteinases in the death of neuronal PC12 and primary cultured rat microglial cells induced by 6-hydroxydopamine (6-OHDA). In both neuronal PC12 and microglial cells, 6-OHDA (10-200 microM) induced apoptosis in a dose-dependent manner as judged by the DNA break. The 6-OHDA was ineffective in Bcl-2-overexpressing neuronal PC12 cells. Pretreatment of these cells with two caspase inhibitors, acetyl-Try-Val-Ala-Asp-aldehyde and acetyl-Asp-Glu-Val-Asp-aldehyde, prevented the 6-OHDA-induced apoptosis. Pepstatin A and leupeptin, potent inhibitors of aspartic and cysteine proteinases, respectively, partly inhibited the apoptosis of microglia but not neuronal PC12 cells. In contrast, GBR12935, a dopamine uptake inhibitor, significantly inhibited the apoptotic death of neuronal PC12 cells but not microglia. These results suggest that mechanisms by which 6-OHDA induces apoptosis in these two cell types are distinct; 6-OHDA incorporated into neuronal PC12 cells and its metabolites may activate the caspase-like enzymes, whereas oxidative metabolites of the agent produced extracellularly may activate the caspase and the endosomal/lysosomal proteolytic systems in microglia.

Animals↗