Biomedical subjects

K Tanabe

Publications and source records attributed to K Tanabe.

659 records · Page 37Linked to original sources

PubMedDate not supplied

Left atrial thrombus formation immediately after cardioversion of atrial fibrillation despite adequate anticoagulant therapy.

We observed a patient who exhibited de novo left atrial thrombus formation after cardioversion, despite administration of adequate anticoagulant therapy. Preexisting atrial thrombus was excluded by transesophageal echocardiography. Preexisting severe left atrial mechanical dysfunction may be considered as a risk factor for de novo thrombus formation after cardioversion, as well as the poor outcome of cardioversion.

Adult↗

PubMedDate not supplied

Stage-dependent inhibition of Plasmodium falciparum by potent Ca2+ and calmodulin modulators.

The effects of Ca2+ channel blockers, verapamil, nicardipine and diltiazem, and of potent calmodulin (CaM) inhibitors, trifluoperazine (TFP), calmidazolium, W-7 and W-5, on Plasmodium falciparum in culture were examined. Among Ca2+ blockers, nicardipine was the most potent with the 50% inhibitory concentration (IC50) of 4.3 microM at 72 h after culture. Parasites were more sensitive to calmidazolium and W-7 with IC50 of 3.4 and 4.5 microM, respectively, than to TFP and W-5. All Ca2+ blockers and CaM inhibitors suppressed parasite development at later stages. Nicardipine, diltiazem, calmidazolium and W-5 also retarded parasite development at earlier stages and/or subsequent growth following pretreatment. Verapamil, nicardipine, TFP and calmidazolium reduced erythrocyte invasion by merozoites. Fluorescence microscopy with the cationic fluorescent dye rhodamine 123 revealed that nicardipine, TFP and calmidazolium depolarized both the plasma membrane and mitochondrial membrane potentials of the parasite. It is therefore considered that although all Ca2+ and CaM antagonists tested here influence parasite development at later stages, they are multifunctional, having effects not directly associated with Ca2+ channels or CaM.

Animals↗

PubMedDate not supplied

5S ribosomal RNA sequence of Pneumocystis carinii and its phylogenetic association with "Rhizopoda/Myxomycota/Zygomycota group".

The cytoplasmic 5S ribosomal RNA sequence from Pneumocystis carinii was determined and compared with those of 382 eukaryotes and an evolutionary tree was constructed to establish the phylogenetic position of Pneumocystis. The data suggest that Pneumocystis is associated with the Rhizopoda/Myxomycota/Zygomycota group but not with common fungi, such as Ascomycota or Basidiomycota, nor with other protozoa.

Animals↗

PubMedDate not supplied

Structure of major surface determinants and DNA diagnosis of Pneumocystis carinii.

Pneumocystis carinii is a pathogen which causes fatal pneumonia in patients with the acquired immune deficiency syndrome (AIDS). To facilitate the basic study of P. carinii, we have analyzed its major surface proteins by both immunochemical and biochemical methods. The major protein components of both cysts and trophozoites are a group of proteins called "P115" with apparent masses of 105-120 kd. It includes 6 isoelectric variants. A monoclonal antibody raised against cysts recognizes all 6 variants and reacts with epitopes located in the cell wall indicating that P115 is an immunoreactive surface component. The isoelectric variants contain identical or closely related protein components and they are mannose-rich glycoproteins. The isoelectric variation may be due primarily to differences in glycosylation. The majority of sera from humans with diagnosed pneumocystosis that were tested reacted strongly with the P115 proteins. To develop probes for DNA diagnosis and to facilitate molecular studies, a genomic DNA library of P. carinii has been constructed. Some of these clones were used for DNA hybridization analysis of rat and human lungs.

Acquired Immunodeficiency Syndrome↗

PubMedDate not supplied

Stable patterns of allelic diversity at the Merozoite surface protein-1 locus of Plasmodium falciparum in clinical isolates from southern Vietnam.

The extent of allelic diversity at the Merozoite Surface Protein-1 locus of Plasmodium falciparum (PfMSP-1) was examined in isolates collected from symptomatic patients living in a mesoendemic area in southern Vietnam. The variable blocks 2, 4 and 10 were typed by polymerase chain reaction and 24 PfMSP-1 gene types were defined as unique combinations of allelic types detected in each variable block. Nineteen PfMSP-1 gene types were identified and 182 parasite populations were fully typed among 102 isolates. Forty-eight (47%) patients harbored more than one typed parasite population, and one patient had at least eight genetically distinct subpopulations. As previously shown in the same endemic area, recombination between blocks 4 and 10 was significantly less frequent than expected from random assortment of allelic types. The distribution of PfMSP-1 gene types, however, did not differ significantly from that observed in isolates collected in the same area 17-24 mo before the present study. Furthermore, the prevalence of the most common gene types and the average number of different gene types harbored by the same host did not decrease with age. This argues against the prominence of frequency-dependent immune selection of PfMSP-1 polymorphisms in this parasite population.

Adolescent↗

PubMedDate not supplied

Sequence diversity and linkage disequilibrium within the merozoite surface protein-1 (Msp-1) locus of Plasmodium falciparum: a longitudinal study in Brazil.

The merozoite surface protein-1 (MSP-1) is a major vaccine candidate for the asexual blood stage of malaria. We examined both the extent of sequence diversity in block 17, the 3' end of Msp-1 gene coding for a 19-kDa polypeptide (MSP-1(19)) putatively involved in red blood cell binding, and the patterns of linkage disequilibrium between polymorphic sites throughout the Msp-1 locus. The parasite population sample consisted of Plasmodium falciparum isolates collected between 1985 and 1998 in Rondĵnia, an area of hypoendemic malaria transmission in the southwestern Brazilian Amazon. Results were summarized as follows. (1) Seven block-17 sequence variants or haplotypes were found among 130 isolates, including two new haplotypes (novel combinations of previously reported amino acid replacements), here named Brazil-1 (E-TSR-F) and Brazil-2 (Q-TSR-F). (2) As previously shown for other Msp-1 polymorphisms, frequencies of block-17 haplotypes displayed significant temporal variation. (3) Extensive linkage disequilibrium was demonstrated between neighboring dimorphic sites within block 17, as well as between polymorphisms at the 5' and 3' ends of Msp-1 (map distance range: 3.83-4.99 kb). (4) The overall patterns of linkage disequilibrium within Msp-1 remained stable over a period of nearly one decade, and examples of possible 'epidemic' expansion of parasites carrying particular Msp-1 alleles were found in the 1980s and 1990s. These results are discussed in relation to the population biology of P. falciparum and the development of malaria vaccines based on MSP-1.

Alleles↗

PubMedDate not supplied

Allelic diversity at the merozoite surface protein-1 (MSP-1) locus in natural Plasmodium falciparum populations: a brief overview.

The merozoite surface protein-1 (MSP-1) locus of Plasmodium falciparum codes for a major asexual blood-stage antigen currently proposed as a major malaria vaccine candidate. The protein, however, shows extensive polymorphism, which may compromise its use in sub-unit vaccines. Here we compare the patterns of allelic diversity at the MSP-1 locus in wild isolates from three epidemiologically distinct malaria-endemic areas: the hypoendemic southwestern Brazilian Amazon (n = 54), the mesoendemic southern Vietnam (n = 238) and the holoendemic northern Tanzania (n = 79). Fragments of the variable blocks 2, 4a, 4b and 6 or 10 of this single-copy gene were amplified by the polymerase chain reaction, and 24 MSP-1 gene types were defined as unique combinations of allelic types in each variable block. Ten different MSP-1 types were identified in Brazil, 23 in Vietnam and 13 in Tanzania. The proportion of genetically mixed infections (isolates with parasites carrying more than one MSP-1 version) ranged from 39% in Brazil to 44% in Vietnam and 60% in Tanzania. The vast majority (90%) of the typed parasite populations from Brazil and Tanzania belonged to the same seven most frequent MSP-1 gene types. In contrast, these seven gene types corresponded to only 61% of the typed parasite populations from Vietnam. Non-random associations were found between allelic types in blocks 4a and 6 among Vietnamese isolates, the same pattern being observed in independent studies performed in 1994, 1995 and 1996. These results suggest that MSP-1 is under selective pressure in the local parasite population. Nevertheless, the finding that similar MSP-1 type frequencies were found in 1994 and 1996 argues against the prominence of short-term frequency-dependent immune selection of MSP-1 polymorphisms. Non-random associations between MSP-1 allelic types, however, were not detected among isolates from Brazil and Tanzania. A preliminary analysis of the distribution of MSP-1 gene types per host among isolates from Tanzania, but not among those from Brazil and Vietnam, shows significant deviation from that expected under the null hypothesis of independent distribution of parasites carrying different gene types in the human hosts. Some epidemiological consequences of these findings are discussed.

Alleles↗

PubMedDate not supplied

Variation in bacterial count in otorrhea from cases of chronic otitis media depending upon the method of antibiotic administration.

Patients with chronic otitis media (COM) were divided into two groups, one to be given Cephalexin (CEX) orally and the other to be given CEX ear drops locally. The counts of viable bacteria in otorrheal samples collected before and after CEX administration were determined. The incidence of decrease in the count of bacteria was higher in the group given ear drops than in the group given oral doses. The magnitude of decrease was greater in the former group. Various concentration of CEX representing the levels of the drug considered available at an otitis focus following oral administration were added to otorrheal preparations placed in biophotometer cells. After 24 hours of incubation, bacteria as undetected initially in the otorrhea were found in the biophotometer cells in 3 of 14 cases of COM.

Administration, Oral↗

PubMedDate not supplied

A phase II trial of mitomycin C, 5'-deoxy-5-fluorouridine, etoposide and medroxyprogesterone acetate (McVD-MPA) as a salvage chemotherapy to anthracycline-resistant tumor in relapsed breast cancer and its mechanism(s) of antitumor action.

To assess the therapeutic efficacy in the combination of mitomycin C (MMC), 5'-deoxy-5-fluorouridine (5'-DFUR), etoposide (VP-16) and medroxyprogesterone acetate (MPA) (McVD-MPA) to anthracycline-resistant tumor as a salvage chemotherapy, a phase II trial was conducted in patients with relapsed breast cancer. Fifty-five patients were enrolled in this trial and 54 were assessable, who had all previously been treated with an anthracycline regimen. The treatment schedule was designed with the intravenous administration of MMC (6 mg/m2) on day 1 followed by peroral administration of VP-16 (75 mg/m2) on day 2, 4, 6 and the peroral administration of 5'-DFUR (600 mg/m2) and MPA (400 mg/m2) on day 1 through 21 in one cycle. The overall tumor response rate was 40.7% (22/54) including 16.6% (9 cases) in complete response and 24.0% (13 cases) in partial response, and the long no change (NC) was observed in 18.5% (10/54) out of 44.4% (24/54) in NC. Of the patients with primary resistance to anthracycline 30.0% responded to McVD-MPA therapy. Bone and liver metastases responded in 50.0% and 50.0%, whereas soft tissue and lung metastases responded in 36.8% and 35.2%, respectively. The mean time to response and response duration were 2.7 and 15.6 months, respectively. The overall survival of the patient treated with the McVD-MPA was superior to the non-treatment of second line therapy, and the median survival between McVD-MPA and non-treatment was 86 days and 50 days, respectively. The major adverse effect was observed in hematological toxicity (31.7%) such as leukopenia and thrombocytopenia and non-hematological toxicity of gastrointestinal events (31.7%), the toxicity was less than grade 2, and was tolerable during the treatment. In the experiment of MDA-MB-231 breast cancer cell line that was overexpressed with P-glycoprotein (P-gp) and multidrug resistance associated protein (MRP), the mechanism(s) by which McVD-MPA induces the antitumor effect to anthracycline-resistant tumor may be explained at least in part as follows: i) The treatment of MMC suppressed the expression of P-gp and MRP in a dose-and time-dependent manner, connecting the increase of the intracellular concentration of VP-16; ii) The treatment of MMC enhanced the expression of thymidine phosphorylase to increase the production of 5-FU from 5'-DFUR in the antiangiogenic effect of MPA. These results indicate that the combination chemotherapy of the McVD-MPA may be an effective regimen to anthracycline-resistant tumor as a salvage chemotherapy to prolong the survival in the patient with relapsed breast cancer.

ATP Binding Cassette Transporter, Subfamily B↗

PubMedDate not supplied

[Changes in hemodynamics and catecholamines during single-level exercise at the anaerobic threshold and 120% of the anaerobic threshold in normal subjects].

Exercise training usually involves the sustained performance of exercise at a prescribed intensity. The effects of exercise performed at the anaerobic threshold (AT) have been widely studied. The effects of single-level exercise on catecholamines and cardiac function were assessed at the AT, and at 120% of the AT in eight healthy Japanese men (mean age 21.9 +/- 1.8 years). 1) Symptom-limited exercise testing utilized the ramp protocol with a bicycle ergometer (20 watts/min) for measuring AT and peak oxygen uptake (peak VO2). 2) Exercise testing was repeated on another day, following the same protocol, with blood sampled to measure norepinephrine (NE) and epinephrine (E) in the resting control state and at the AT and peak exercise. 3) Single-level exercise testing at the AT and at 120% of AT utilized the bicycle ergometer on yet another day. Blood for measurement of NE and E was drawn at 3 and 7 min after achieving a steady-state condition. In addition, the cardiac index (CI) and stroke index (SI) were measured by the CO2 rebreathing method. (1) Mean AT and peak VO2 were 18.3 +/- 1.3 and 40.2 +/- 3.0 ml/min/g, respectively. (2) NE and E measured during ramp exercise testing increased rapidly when the intensity of exercise exceeded the AT. NE measured after 3 and 7 min at the AT during single-level exercise equalled 94.7% and 94.5% of the NE value measured at the AT of ramp exercise, respectively. NE measured after 3 and 7 min at 120% of the AT during single-level exercise was 124.7% and 144.7% at the AT of ramp exercise, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMedDate not supplied

[Changes in gadolinium-DTPA enhanced magnetic resonance signal intensity ratio in hypertrophic cardiomyopathy].

Serial gadolinium-diethylene-triamine-pentaacetic acid (Gd-DTPA) enhanced magnetic resonance (MR) signal intensity ratios were measured in 6 normal subjects and 20 hypertrophic cardiomyopathy (HCM) patients to try to differentiate normal from disorganized myocardial tissue. Images were obtained at 10-minute intervals 5-60 minutes after Gd-DTPA (0.1 mmol/kg) injection. The signal intensity ratio (myocardial signal intensity/skeletal muscle signal intensity) was measured at both hypertropic and nonhypertrophic regions in each image at the apex and mid-ventricular levels. The signal intensity ratio was standardized to compare each case. Hypertrophic myocardium was classified into two types. Type I in 11 of 20 patients was visualized as a homogeneous image, while type II in the other 9 patients was revealed as a mixed isointensity and high intensity area. The peak value of the standardized signal intensity ratio at the apex level was 1.28 +/- 0.09 in HCM patients and 1.23 +/- 0.06 in normal subjects, and at the mid ventricular level was 1.26 +/- 0.07 in hypertrophic regions, 1.17 +/- 0.12 in non-hypertrophic regions, and 1.16 +/- 0.07 in normal subjects. Thirty minutes after Gd injection, the standardized signal intensity ratio at the apex level was 1.21 +/- 0.08 in HCM patients and 1.07 +/- 0.08 in normal subjects, and those at the mid ventricular level was 1.20 +/- 0.09 in hypertrophic regions, 1.11 +/- 0.11 in non-hypertrophic regions, and 1.04 +/- 0.06 in normal subjects. The delayed decay of the signal intensity ratio and high signal intensity ratio in Gd-DTPA enhanced MR images are useful in myocardial tissue characterization in hypertrophic cardiomyopathy.

Cardiomyopathy, Hypertrophic↗