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Biomedical subjects

M Yokota

Publications and source records attributed to M Yokota.

At least 37 records · Page 2Linked to original sources
PubMed2001

Birth of a healthy baby following vitrification of human blastocysts.

OBJECTIVE: To assess vitrification of human blastocysts. DESIGN: Retrospective study of blastocyst vitrification. SETTING: A private clinic. PATIENT(S): Twenty couples with different types of infertility. INTERVENTION(S): Blastocysts were frozen with rapid vitrification and then transferred after thawing. We vitrified blastocysts using a modification of Ishimori's vitrification solution of ethylene glycol and dimethyl sulfoxide (VSED). MAIN OUTCOME MEASURE(S): After thawing, survival was defined by the embryo's development morphology after 6 hours or overnight culture. RESULT(S): Eighteen of 20 patients underwent treatment. Of 45 vitrified blastocysts, 36 survived, for a survival rate of 80% (36 of 45). The implantation rate was 21.9% (7 of 32), and the pregnancy rate (per embryo transfer cycle) was 33.3% (6 of 18). One of the pregnancies resulted in the delivery of a healthy baby. CONCLUSION(S): Supernumerary embryos were grown in culture to blastocysts, and the survival rate of vitrified-thawed blastocysts was the same as that for slow freezing of early stage embryos. Blastocyst vitrification should prove effective for clinical treatment. The present results strongly suggest that this rapid and successful vitrification procedure will replace conventional cryopreservation in the future.

Blastocyst↗
PubMed2001

Birth of healthy twins from in vitro development of human refrozen embryos.

OBJECTIVE: To avoid the risk of ovarian hyperstimulation syndrome and promote pregnancy rate by freezing pronuclear embryos at the oocyte retrieval and using developed refrozen supernumerary embryos in the event of failed pregnancies. DESIGN: A case study. SETTING: Private IVF center. PATIENT(S): Healthy infertile woman undergoing IVF treatment. INTERVENTION(S): Slowly frozen and rapidly refrozen embryos at varying stages of embryonic development were transferred. MAIN OUTCOME MEASURE(S): Survival rate of refrozen and thawed embryos; safety of refrozen embryo transference. RESULT(S): Fertilized pronuclear embryos that were frozen, thawed, and developed to morula embryos were subsequently vitrified, rethawed, and cultured until blastocyst formation before transfer. Healthy fraternal twins were born by caesarian section. The result of transfer was the novel finding of a successful delivery after the use of refrozen embryos. CONCLUSION(S): The transfer of refrozen supernumerary embryos resulted in successful pregnancy and delivery. We will continue to investigate the safety and efficacy of the elective freezing of all embryos as well as their refreezing so that supernumerary embryos can be reused to avoid ovarian hyperstimulation syndrome or in cases of repeated failed pregnancies.

Cryopreservation↗
PubMed2001

Biphasic changes in left ventricular end-diastolic pressure during dynamic exercise in patients with nonobstructive hypertrophic cardiomyopathy.

OBJECTIVES: The aim of this study was to clarify the serial changes in left ventricular (LV) end-diastolic pressure (LVEDP) during dynamic exercise in patients with hypertrophic cardiomyopathy (HCM). BACKGROUND: Although HCM is characterized by impaired resting LV diastolic function, serial changes in LVEDP during exercise have not been characterized. METHODS: We simultaneously measured LV pressure and LV dimensions during symptom-limited supine bicycle exercise in 5 healthy individuals and 20 patients with HCM. Exercise thallium-201 scintigraphic studies were also performed. RESULTS: The LVEDP (baseline: 12 +/- 5 mm Hg) progressively increased to a maximum value at peak exercise (28 +/- 8 mm Hg) in 11 patients with HCM (group I). In the remaining nine patients with HCM (group II), changes in LVEDP during exercise were biphasic, with an initial progressive increase and a subsequent gradual decline up to peak exercise (14 +/- 4 mm Hg at baseline, 27 +/- 5 mm Hg at the critical heart rate, 16 +/- 3 mm Hg at peak exercise). Exercise-induced changes in LV dimensions and LV peak systolic pressures were similar in both groups. However, the maximum first derivative of LV pressure was greater and the LV pressure half-time was shorter in group II than in group I at a similar peak exercise heart rate. The biphasic changes in LVEDP disappeared by pretreatment with propranolol. The LV hypertrophy scores were higher in group I than in group II. Exercise thallium-201 images showed more severe perfusion defects in group I than in group II patients. CONCLUSIONS: The biphasic changes in LVEDP seen during exercise may be related to improved coronary microcirculation in response to beta-adrenergic stimulation in patients with mild to moderate HCM.

Adult↗
PubMed2001

Evaluation of prostate-specific antigen (PSA) membrane test for forensic examination of semen.

Prostate-specific antigen (PSA) is a glycoprotein produced by the prostatic gland and functions to liquefy the seminal fluid. Recently several PSA membrane test kits utilizing an immunochromatographic assay are commercially available for clinical screening of PSA concentration in serum. In this study, we applied the three PSA test kits to forensic examination of semen, and evaluated the sensitivity and specificity of the PSA test kits. The specificity were the same, but SMITEST PSA Card had the highest sensitivity among the three kits. Furthermore we certified that the SMITEST PSA Card was little affected by heat or contaminants such as other body fluids, reagent of preliminary test for semen stain and spermicides, and the PSA kit was applied to 30 casework samples.

Journal Article↗
PubMed2001

Prevalence of hepatitis B or C virus infections in patients with non-Hodgkin's lymphoma.

BACKGROUND: Hepatitis C virus (HCV) and hepatitis B virus (HBV) are not only hepatotropic, but also lymphotropic viruses. Recently, some reports suggested that these viruses may participate in the development of malignant lymphoproliferative disorders. METHODS: We investigated the prevalence of HCV or HBV infection in 348 patients with non-Hodgkin's lymphoma (NHL). We also compared these prevalences with those in blood donors as a control group representing the general population in our area (n= 1,513,358). Next, we evaluated the clinical and pathologic characteristics of HCV- or HBV-infected NHL cases. Non-Hodgkin's lymphoma was classified according to the Working Formulation classification. RESULTS: Thirty-seven cases (14.9%) were found to be infected with HCV or HBV; of these, 20 (8.1%) were infected with HCV, and 17 (6.9%) with HBV. In male NHL patients, the rate of HCV infection was significantly higher than in an age- and sex-matched population in the same area (P < 0.001, Mantel-Haenszel test). The rate of HBV infection also tended to be higher in the population (P = 0.0551). In contrast, in female NHL patients, the rate of HCV or HBV infection was not higher than in the general population. In HCV-infected cases, 15 cases (75%) had B-cell NHL and 16 cases (80%) were classified as being in the intermediate grade; B-cell NHL comprised 83% of all NHL cases. In HBV-infected NHL cases, 11 (65%) were of B-cell type and 10 (58%) were classified as being in the intermediate grade. CONCLUSIONS: The high prevalence of HCV or HBV infections in our study population provides epidemiologic evidence suggesting that HCV and HBV infections may be involved in the development of a subgroup of NHL in males. Our investigation also revealed that both HCV- and HBV-infected NHL patients showed certain similarities in clinical and pathologic manifestations.

Adult↗
PubMed2001

Cardiac functional and structural alterations induced by endotoxin in rats: importance of platelet-activating factor.

OBJECTIVE: In this study, we evaluated the time course of the alterations in left ventricular (LV) dimensions, LV wall thickness, and LV systolic function in rats with endotoxemia by using echocardiography as well as myocardial histopathologic assessments. Our second goal was to examine whether pretreatment with a platelet-activating factor (PAF) antagonist would ameliorate the lipopolysaccharide (LPS)-induced cardiovascular collapse during the early phase. DESIGN: A prospective, controlled, in vivo animal laboratory study. SETTING: Research laboratory at a university. SUBJECTS: Male, Wistar rats (8-9 wks old; n = 83). INTERVENTIONS: In pentobarbital-anesthetized rats, the right carotid artery was cannulated to measure the arterial blood pressure and to sample blood. The right jugular vein also was catheterized for the administration of drugs. LPS (2 mg/kg) derived from Klebsiella pneumoniae or physiologic saline was administered in the presence or absence of pretreatment with TCV-309, a specific potent PAF antagonist. Echocardiographic studies were performed with an 8- to 13-MHz transducer. MEASUREMENTS AND MAIN RESULTS: LPS administration immediately induced progressive hypotension. The maximal hypotensive response was observed at 10 mins after LPS infusion with mean arterial pressure decreasing from 119 +/- 2 to 56 +/- 3 mm Hg (p < .001). LV end-diastolic internal dimensions decreased from 6.4 +/- 0.1 to 3.1 +/- 0.1 mm (p < .001) at 30 mins after LPS and remained significantly reduced compared with control rats. LV end-systolic dimensions also decreased dramatically from 3.5 +/- 0.2 to 0.5 +/- 0.1 mm (p < .001) at 30 mins after LPS and remained significantly reduced throughout the experiment. LV fractional shortening increased from 45 +/- 1% to 84 +/- 2% (p < .001) at 30 mins after LPS and remained elevated compared with control rats. LV wall thickness increased strikingly from 15 mins until 2 hrs after LPS infusion. Pathologic studies demonstrated marked congestion of capillaries and mild edema in the LV myocardium. The hematocrit increased after the administration of LPS. LPS markedly increased sympathetic tone as demonstrated by the elevation of plasma concentrations of epinephrine and norepinephrine. There was no elevation of concentrations of nitrite and nitrate. Pretreatment with TCV-309, a specific potent PAF antagonist, reduced LPS-induced hypotension and attenuated LV functional and structural changes. TCV-309 administration reduced the LPS-induced adrenergic activation and hemoconcentration. CONCLUSIONS: The hypotension that occurred during the initial phase of LPS-induced shock was accompanied by LV functional and structural alterations. The marked increase in LV wall thickness can be ascribed to the congestion of capillaries and edema in the LV myocardium. Pretreatment with a PAF antagonist reduced LPS-induced alterations. PAF may play a pivotal role during the initial phase of LPS-induced cardiovascular responses.

Animals↗
PubMed2001

Increased incidence of bone metastases in hepatocellular carcinoma.

OBJECTIVES: Recently, we often encounter hepatocellular carcinoma patients with bone metastases. We therefore examined the changes in the incidence of bone metastases in hepatocellular carcinoma from 1978 to 1997 and tried to identify the characteristic clinical features. We also discuss the reasons for the increased incidence of bone metastasis in hepatocellular carcinoma. METHODS: A total of 673 patients with hepatocellular carcinoma during the period 1978-1997 were studied. Bone metastasis was screened by bone scintigraphy, and bone lesions were confirmed by plain radiography, computed tomography and/or magnetic resonance imaging. The serum levels of the C-terminal telopeptide of type 1 collagen, which represent osteoclastic bone resorption, were also measured. RESULTS: The incidence of bone metastasis during the decade 1988-1997 was significantly higher than that during the period 1978-1987. The median survival time of patients with hepatocellular carcinoma during 1988-1997 was also significantly longer than that during 1978-1987. Portal thrombus was found in about half of the patients with bone metastases. The most common site of bone metastases was the vertebra followed by the pelvis, rib and skull in that order. All bone lesions depicted by plain radiograph, computed tomography and/or magnetic resonance imaging were of the osteolytic type, and the serum levels of C-terminal telopeptide of type 1 collagen were significantly elevated in the patients with bone metastases. CONCLUSIONS: The increased incidence of bone metastasis in hepatocellular carcinoma in the decade 1988-1997 is first attributed to the prolonged survival rate of hepatocellular carcinoma patients due to recent progress in both the diagnosis and treatment of the disease. Dissemination of hepatocellular carcinoma cells to the vertebra through the portal vein-vertebral vein plexuses due to the presence of portal thrombus and/or portal hypertension may be related to a higher incidence of bone metastasis in hepatocellular carcinoma. Both an early diagnosis and timely treatment of bone metastases are thus called for in the follow-up of hepatocellular carcinoma patients.

Adult↗
PubMed2001

Anti-fibrin antibody binding in valvular vegetations and kidney lesions during experimental endocarditis.

In Streptococcus sanguinis (sanguis) induced experimental endocarditis, we sought evidence that the development of aortic valvular vegetation depends on the availability of fibrin. Endocarditis was induced in New Zealand white rabbits by catheter placement into the left ventricle and inoculation of the bacteria. Fibrin was localized in the developing vegetation with 99mTechnetium (Tc)-labeled anti-fibrin antibody one or three days later. When rabbit anti-fibrin antibody was given intravenously on day 1, the mass of aortic valvular vegetation was significantly reduced at day 3; infusion of non-specific rabbit IgG showed no effect. The 99mTc-labeled anti-fibrin antibody also labeled kidneys that showed macroscopic subcapsular hemorrhage. To learn if the deposition of fibrin in the kidneys was a consequence of endocarditis required a comparison of farm-bred and specific pathogen-free rabbits before and after the induction of endocarditis. Before induction, the kidneys of farm-bred rabbits were labeled, but specific pathogen-free rabbits were free of labeling and signs of macroscopic hemorrhage. After 3 days of endocarditis, kidneys of 10 of 14 specific pathogen-free rabbits labeled with 99mTc-labeled anti-fibrin antibody and showed hemorrhage. Kidney lesions were suggested to be a frequent sequellae of S. sanguinis infective endocarditis. For the first time, fibrin was shown to be required for the continued development of aortic valvular vegetations.

Animals↗
PubMed2001

Inhibition by carbapenem antibiotic imipenem of intestinal absorption of valproic acid in rats.

The concomitant use of carbapenem antibiotics with valproic acid has been prohibited because panipenem induced a decrease in plasma concentration of valproic acid in epileptic patients during valproic acid therapy. To clarify the possible mechanism of the carbapenem-valproic acid interaction, we investigated the effect of imipenem on the pharmacokinetic behaviour of valproic acid in rats. Co-administration of imipenem (30 mg kg(-1), i.v.) induced a decrease in the peak plasma concentration of valproic acid after oral administration. However, the imipenem-induced decrease in plasma concentrations of valproic acid was not observed within 60 min after intravenous injection of valproic acid. By utilizing in-situ vascular and luminal perfused small intestine, it was confirmed that absorption of valproic acid from the luminal to the vascular perfusate was decreased in the presence of imipenem (0.5 mM) in the vascular perfusate. The everted gut sac method was used to determine the effect of imipenem on active transport of valproic acid. The accumulation of valproic acid on the serosal side of the intestinal sac against the concentration gradient was reduced by lactic acid that inhibits the carrier-mediated transport of valproic acid across the intestinal brush-border membrane. However, imipenem did not affect the active transport of valproic acid. Therefore, the inhibition by imipenem of valproic acid absorption may be caused by a mechanism different from that of lactic acid. In conclusion, imipenem inhibits the intestinal absorption of valproic acid, which contributes to the decrease in plasma concentration of valproic acid after oral administration.

Administration, Oral↗
PubMed2001

Mild to severe lithium-induced nephropathy models and urine N-acetyl-beta-D-glucosaminidase in rats.

Long-term treatment with lithium induces functional and/or structural disturbances in the kidneys. However, no procedure has been established for the early diagnosis of lithium intoxication. In this study, we prepared mild to severe lithium-induced nephropathy rat models and examined the usefulness of urine N-acetyl-beta-D-glucosaminidase (NAG) for the early diagnosis of lithium-induced renal insufficiency. Lithium was administered by repeated intraperitoneal injection (1, 2 and 4 mEq/kg/day for 10 days). We also measured the plasma creatinine and paraaminohippuric acid (PAH) clearance, and observed renal histological changes. Lithium pretreatment elevated the plasma creatinine level and decreased PAH clearance in a dose-dependent manner. The NAG level in the lithium 4 mEq/kg group was very high. The levels in the lithium 1 mEq/kg and 2 mEq/kg groups were almost the same and were higher than the control group. A histological examination of the kidney revealed glomerular congestion and/or atrophy and tubular expansion in all of the groups except the control group. These histological changes were dose-dependent. In conclusion, urine NAG may be useful in the early diagnosis of renal side effects caused by lithium therapy. When the urine NAG level becomes high in a patient taking lithium for bipolar disorder, the physician may need to consider lithium-induced renal insufficiency.

Acetylglucosaminidase↗
PubMed2001

Scattering of a Hermite-Gaussian beam field by a chiral sphere.

Scattering of a Hermite-Gaussian beam field by a chiral sphere is analyzed. A Hermite-Gaussian beam field is expressed as a superposition of multipole fields at complex-source points. Electromagnetic fields are expanded in terms of the spherical vector wave functions. The unknown expansion coefficients for the scattered field and the internal field are determined by the boundary conditions. As numerical examples, the scattered near fields of the beam incidence are calculated, and the effects of the chirality and the radius of the chiral sphere on the fields are examined. The results for a Gaussian beam incidence are also compared with those of a plane-wave incidence.

Journal Article↗
PubMed2001

[Right ventricular outflow tract reconstruction for pulmonary atresia with ventricular septal defect: the possibility of ventriculo-arterial direct anastomosis].

Between September 1997 and December 2000, 29 patients with pulmonary atresia associated with ventricular septal defect were undergone corrective surgery. The age at operation ranged from 24 days to 14.7 years. The 5 patients were younger than 3 months. The body weight at operation ranged from 1.5 kg to 35.8 kg. 10 patients had MAPCAs. 21 patients had been undergone modified Blolock-Taussig shunt and/or uniforcalization of pulmonary artery (PA). We could perform right ventricular outflow tract reconstruction with ventriculo-arterial direct anastomosis in 19 patients (65%) (4/10; patients with MAPCAs, 3/5; younger than 3 months). We performed pulmonary angioplasty on stenotic and/or underdeveloped leasions as a concomitant procedure in 13/19 cases. Our technique is composed of 4 points, (1) fully mobilizing central and distal pulmonary artery (PA), (2) dissecting the PA with connective tissue together, (3) pulmonary arterial wall flap, (4) right ventricular outflow tract reconstruction during cardiac arrest.

Adolescent↗
PubMed2001

[Total anomalous pulmonary venous connection].

Recently the surgical results of simple (isolated) total anomalous pulmonary venous connection have improved markedly, and even the most severely affected patients presenting with marked hypoxia soon after birth have become salvagable partly due to the perioperative use of nitric oxide and extracorporeal membrane oxygenation. However, the outcome after complex surgery, particularly in asplenia, is still very poor in newborns. Common pulmonary vein atresia is still an ominous diagnosis and according to the literature only a few patients have survived surgery. The results of reoperation for postoperative pulmonary vein stenosis are also poor, although the good results of the "sutureless technique" which have recently been reported are encouraging. Prenatal diagnosis using echocardiography is difficult, but postnatal diagnosis using echocardiography and magnetic resonance imaging is usually precise and can obviate the need for cardiac catheterization which often aggravates the hypoxic status in critically ill infants.

Humans↗
PubMed2001

[Association of polymorphisms of the transforming growth factor-beta 1 gene with genetic susceptibility to osteoporosis].

Osteoporosis exhibits a substantial genetic component. Although polymorphisms of a variety of genes have been associated with bone mineral density and genetic susceptibility to osteoporosis, the genes responsible for these traits have not been definitively identified. We have shown that a T869-->C polymorphism of the transforming growth factor-beta 1 gene, which results in a Leu-->Pro substitution at amino acid 10, is associated with bone mineral density in Japanese adolescents and postmenopausal women, with genetic susceptibility to both osteoporosis and vertebral fracture, and with the outcome of treatment for osteoporosis with active vitamin D. We have also shown that a C-509-->T polymorphism in the promoter region of this gene is associated with both bone mineral density and the prevalence of osteoporosis in postmenopausal women. In addition, analysis of combined genotypes for both the C-509-->T and T869-->C polymorphisms revealed that bone mineral density decreases and the susceptibility to osteoporosis increases with the number of T alleles. Thus, combined genotyping of the C-509-->T and T869-->C polymorphisms may prove beneficial in the prevention of osteoporosis in postmenopausal Japanese women. I here review the association of transforming growth factor-beta 1 gene polymorphisms with genetic susceptibility to osteoporosis, which has provided insight into the function of transforming growth factor-beta 1 as well as into the role of genetic factors in the development of osteoporosis.

Adolescent↗
PubMed2001

Evaluation of left ventricular function using electrocardiographically gated myocardial SPECT with (123)I-labeled fatty acid analog.

UNLABELLED: Electrocardiographically (ECG) gated myocardial SPECT with (99m)Tc-tetrofosmin has been used widely to assess left ventricular (LV) function. However, the accuracy of variables using ECG gated myocardial SPECT with beta-methyl-p-(123)I-iodophenylpentadecanoic acid (BMIPP) has not been well defined. METHODS: Thirty-six patients (29 men, 7 women; mean age, 61.6 +/- 15.6 y) with ischemic heart disease underwent ECG gated myocardial SPECT with (123)I-BMIPP and with (99m)Tc-tetrofosmin and left ventriculography (LVG) within 1 wk. LV ejection fraction (LVEF), LV end-diastolic volume (LVEDV), and LV end-systolic volume (LVESV) were determined on gated SPECT using commercially available software for automatic data analysis. These volume-related items on LVG were calculated with an area-length method and were estimated by 2 independent observers to evaluate interobserver validity. The regional wall motion with these methods was assessed visually. RESULTS: LVEF was 41.1% +/- 12.5% on gated SPECT with (123)I-BMIPP, 44.5% +/- 13.1% on gated SPECT with (99m)Tc-tetrofosmin, and 46.0% +/- 12.7% on LVG. Global LV function and regional wall motion between both gated SPECT procedures had excellent correlation (LVEF, r = 0.943; LVEDV, r = 0.934; LVESV, r = 0.952; regional wall motion, kappa = 0.92). However, the correlations of global LV function and regional wall motion between each gated SPECT and LVG were significantly lower. Gated SPECT with (123)I-BMIPP showed the same interobserver validity as gated SPECT with (99m)Tc-tetrofosmin. CONCLUSION: Gated SPECT with (123)I-BMIPP provides high accuracy with regard to LV function and is sufficiently applicable for use in clinical SPECT. This technique can simultaneously reveal myocardial fatty acid metabolism and LV function, which may be useful to evaluate various cardiac diseases.

Electrocardiography↗