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Biomedical subjects

Y Yasui

Publications and source records attributed to Y Yasui.

At least 73 records · Page 4Linked to original sources

Cervical cancer screening among Cambodian-American women.

Southeast Asian women have higher invasive cervical cancer incidence rates and lower Pap testing frequencies than most other racial/ethnic groups in the United States. However, there is little information about the cervical cancer screening behavior of Cambodian-American women. Cambodian residents of Seattle were surveyed in person during late 1997 and early 1998. The PRECEDE model was used to guide the development of items that assessed predisposing, reinforcing, and enabling factors associated with cervical cancer screening participation. The estimated overall survey response was 72%. Four hundred thirteen women completed our questionnaire. Approximately one-quarter (24%) of the respondents had never had a Pap test, and over one-half (53%) had not been screened recently. The following variables were positively associated with a history of at least one Pap smear: younger age, greater number of years since immigration, belief about Pap testing for postmenopausal women, prenatal care in the United States, and physician recommendation. Women who believed in karma were less likely to have ever been screened for cervical cancer than those who did not. Six variables independently predicted recent screening: age; beliefs about regular checkups, cervical cancer screening for sexually inactive women, and the prolongation of life; having a female doctor; and a previous physician recommendation for Pap testing. The study findings indicate that culturally specific approaches might be effective in modifying the cervical cancer screening behavior of immigrant women. Programs targeting Cambodian-Americans are likely to be more effective if they are multifaceted and simultaneously address predisposing, reinforcing, and enabling factors.

Adolescent↗

Colorectal adenomas and the C677T MTHFR polymorphism: evidence for gene-environment interaction?

5,10-Methylene-tetrahydrofolate reductase (MTHFR), an enzyme in folate metabolism, may play a role in the etiology of colorectal adenomas via effects on DNA methylation and nucleotide synthesis. We investigated the association between a common polymorphism (C677T, reduced MTHFR activity) and colorectal adenomas within the Minnesota CPRU case-control study. Cases (n = 527) were diagnosed with colonoscopically confirmed adenomas; controls (n = 645) were derived from the same gastroenterology practice and were polyp free at colonoscopy. Dietary intakes were obtained from a self-administered food-frequency questionnaire prior to colonoscopy. Age- and sex-adjusted odds ratios (ORs) and 95% confidence intervals for the MTHFR genotype were 0.9 (0.7-1.2; CT versus CC wild-type) and 0.8 (0.6-1.3; TT versus CC). The associations between dietary intakes of folate, vitamin B12, vitamin B6, or methionine and risk of adenomas showed consistent patterns dependent upon MTHFR genotype. Individuals with the TT genotype and intakes of any of these nutrients in the lowest tertile were at elevated risk for adenomas (about 2-3-fold when compared with TT genotype with high intakes). These trends were more pronounced among individuals over age 60, resulting in a 3-6-fold increase for low intakes of folate, B12, and B6. An increased risk with increasing alcohol consumption was observed only among those with the CC genotype (P-trend = 0.005); among those with the TT genotype, those with moderate alcohol consumption were at lowest risk (P for interaction P = 0.02). In conclusion, nutrients involved in the MTHFR metabolic pathway may modify the relationship between the MTHFR C677T polymorphism and colorectal adenomas. Low intakes of folate, vitamin B12, and vitamin B6 increase risk among those (particularly the elderly) with the MTHFR TT genotype.

Adenoma↗

Roles of Rho-associated kinase in cytokinesis; mutations in Rho-associated kinase phosphorylation sites impair cytokinetic segregation of glial filaments.

Rho-associated kinase (Rho-kinase), which is activated by the small GTPase Rho, regulates formation of stress fibers and focal adhesions, myosin fiber organization, and neurite retraction through the phosphorylation of cytoskeletal proteins, including myosin light chain, the ERM family proteins (ezrin, radixin, and moesin) and adducin. Rho-kinase was found to phosphorylate a type III intermediate filament (IF) protein, glial fibrillary acidic protein (GFAP), exclusively at the cleavage furrow during cytokinesis. In the present study, we examined the roles of Rho-kinase in cytokinesis, in particular organization of glial filaments during cytokinesis. Expression of the dominant-negative form of Rho-kinase inhibited the cytokinesis of Xenopus embryo and mammalian cells, the result being production of multinuclei. We then constructed a series of mutant GFAPs, where Rho-kinase phosphorylation sites were variously mutated, and expressed them in type III IF-negative cells. The mutations induced impaired segregation of glial filament (GFAP filament) into postmitotic daughter cells. As a result, an unusually long bridge-like cytoplasmic structure formed between the unseparated daughter cells. Alteration of other sites, including the cdc2 kinase phosphorylation site, led to no remarkable defect in glial filament separation. These results suggest that Rho-kinase is essential not only for actomyosin regulation but also for segregation of glial filaments into daughter cells which in turn ensures correct cytokinetic processes.

Amino Acid Sequence↗

Mouse placental cells secrete soluble leptin receptor (sOB-R): cAMP inhibits sOB-R production.

The aims of this study were to identify whether mouse placenta secretes soluble OB-R (sOB-R) and to find the regulating factor of OB-R expression. Total RNAs were extracted from placenta and decidua, and OB-R expression was assessed by Northern blot analysis. Decidua did not express OB-R mRNA. However, OB-R mRNA expression was detectable in the placenta on day 13 of pregnancy, and then it increased and reached a peak on day 17 of pregnancy. Mouse placental cells from day 12 of pregnancy were cultured and OB-R gene expression was assessed by Northern blot analysis. OB-R mRNA expression was detectable from the second day of culture and reached a peak on the third day of culture. To determine whether placental cells release sOB-R, supernatant of cultured placental cells was subjected to Western blot analysis. sOB-R was detected in the medium by the second day of culture and sOB-R release increased up to the fourth day of culture. Addition of leptin to the medium did not affect expression of OB-R mRNA. However, 8-bromo cAMP inhibited both steady-state levels of OB-R mRNA and the amount of sOB-R protein in the medium in a dose- and time-dependent manner. These results suggest that trophoblast cells differentiate, express, and release sOB-R both in vivo and in vitro and that cAMP is one of several potent regulators of sOB-R secretion by the mouse placenta.

8-Bromo Cyclic Adenosine Monophosphate↗

Tectal projections to the parvicellular reticular formation and the upper cervical spinal cord in the rat, with special reference to axon collateral innervation.

After Phaseolus vulgaris leucoagglutinin injection into the lateral part of the superior colliculus (SC) in the rat, labeled fibers and axon terminals in the lower brainstem were distributed not only in the medial reticular formation but also in the lateral tegmental field including the parvicellular reticular formation (RFp). More caudally, in the upper cervical spinal cord labeled fibers with bouton-like varicosities were distributed mainly in laminae V, VII and VIII, with relatively sparse distribution in lamina IX. These labeled axons were found bilaterally with a clear-cut contralateral dominance. After combined injections of rhodamine-dextranamine, Fluoro-ruby (FR) into the RFp and Fluoro-gold (FG) into the upper cervical spinal cord on the same side, SC neurons labeled with FR were intermingled with those labeled with FG in the lateral part of the SC contralateral to the injection sites. In the stratum griseum intermediale, some of them were double-labeled with both tracers. Our results suggest that SC neurons innervating both the RFp and the cervical spinal cord may be involved in the coordination of head and mouth movements.

Animals↗

Developmental appearance of oligodendrocytes in the embryonic chick retina.

The axons of the optic nerve layer are known to be myelinated by oligodendrocytes in the chick retina. The development of the retinal oligodendrocytes has been studied immunohistochemically with antibodies against oligodendrocyte lineage: monoclonal antibodies O4 and O1, and an antibody against myelin basic protein. O4 positive (O4+) cells were first detected in the retina on the tenth day of incubation (embryonic day (E)10, stage 36). The labeled cells were located in the optic nerve layer close to the optic fissure. Most were unipolar in shape, extending a leading process with a growth cone toward the periphery of the retina. By E12, unipolar O4+ cells had spread to the middle of the retina. Many O4+ cells close to the optic fissure showed radial arrangement with extension of processes toward the inner limiting membrane. O1+ oligodendrocytes were first observed in the E14 retina positioned just above (interiorly to) retinal ganglion cells. These labeled cells extended fine processes in the optic nerve layer. Limited numbers of myelin basic protein-positive cells were present by E16 and located interiorly to the retinal ganglion cells. In addition to the oligodendrocyte in the optic nerve layer, a limited number of O4+ cells were observed in the inner nuclear layer by E14, and they became O1+ by E18. Furthermore, explant culture experiments showed E10 to be the youngest stage at which the retina contained oligodendrocyte precursors. An intraventricular inj ection of fluorescent dye 1,1',dioctadecyl-3,3,3',3-tetramethylindocarbocyanine perchlorate (DiI) at E6 yielded O4+/DiI+ cells in the retina at E10, which provided direct evidence to support migration of oligodendrocyte precursor into the retina. The present results demonstrated the sequential appearance of the cells of oligodendrocyte lineage and the detailed morphology of the developing oligodendrocytes in the retina. These morphologic features strongly suggested that retinal oligodendrocytes were derived from the optic nerve and spread by migration through the optic nerve layer.

Animals↗

Variation in mammographic breast density by time in menstrual cycle among women aged 40-49 years.

BACKGROUND: Mammography is less effective for women aged 40-49 years than for older women, which has led to a call for research to improve the performance of screening mammography for younger women. One factor that may influence the performance of mammography is breast density. Younger women have greater mammographic breast density on average, and increased breast density increases the likelihood of false-negative and false-positive mammograms. We investigated whether breast density varies according to time in a woman's menstrual cycle. METHODS: Premenopausal women aged 40-49 years who were not on exogenous hormones and who had a screening mammogram at a large health maintenance organization during 1996 were studied (n = 2591). Time in the menstrual cycle was based on the woman's self-reported last menstrual bleeding and usual cycle length. RESULTS: A smaller proportion of women had "extremely dense" breasts during the follicular phase of their menstrual cycle (24% for week 1 and 23% for week 2) than during the luteal phase (28% for both weeks 3 and 4) (two-sided P = .04 for the difference in breast density between the phases, adjusted for body mass index). The relationship was stronger for women whose body mass index was less than or equal to the median (two-sided P<.01), the group who have the greatest breast density. CONCLUSIONS/IMPLICATIONS: These findings are consistent with previous evidence suggesting that scheduling a woman's mammogram during the follicular phase (first and second week) of her menstrual cycle instead of during the luteal phase (third and fourth week) may improve the accuracy of mammography for premenopausal women in their forties. Breast tissue is less radiographically dense in the follicular phase than in the luteal phase.

Adult↗

Isolation, purification, and characterization of a collagen-associated serpin, caspin, produced by murine colon adenocarcinoma cells.

A 45-kDa serpin secreted by a murine colon adenocarcinoma cell line, colon26, was isolated, purified, and characterized. It was found to bind specifically to type I collagen with high affinity and to type III collagen with lower affinity. Immunohistochemical studies of murine embryonic tissues showed a specific distribution of this collagen-associated serpin, named caspin, in relation to the formation of bone, cartilage, teeth, and basement membrane. The expression of caspin in high and low lung metastatic subclones of colon26 cell lines was inversely correlated with their metastatic capacity: low lung metastatic cells secreted higher amounts of caspin than their high lung metastatic counterparts. Caspin also demonstrated high homology with human pigment epithelium-derived factor/early population doubling level cDNA-1, which reportedly induces neuronal differentiation of human retinoblastoma cells and is expressed in association with G0 growth arrest. These findings suggest that caspin/pigment epithelium-derived factor/early population doubling level cDNA-1 is a novel factor that might play a crucial role in embryogenesis and tumor metastasis through binding to the extracellular matrix.

Amino Acid Sequence↗

Patient empowerment and feedback did not decrease pain in seriously ill hospitalized adults.

We tested a nurse clinician-mediated intervention to relieve pain in a group of seriously ill hospitalized adults using a randomized controlled trial at five tertiary care academic centers in the US. The study included 4804 patients admitted between January 1992 and January 1994 with one or more of nine high mortality diagnoses; 2652 were allocated to the intervention and 2152 to usual care. Specially-trained nurse clinicians assessed patients' pain, educated them and their families about pain control, empowered patients to expect pain relief, informed patients' nurses and physicians about level of pain and suggested or used other pain management resources. Patients' pain was determined from hospital interviews with patients and surrogates. Pain 2 and 6 months later or after death and satisfaction with its control at all time periods were also assessed. All analyses were adjusted for baseline risk of being in pain and propensity to be in the intervention group. Overall, 50.9% of patients reported some pain. After adjustment for other variables associated with pain, comparing the intervention to the control group, there was not a statistically significant difference in level of pain (OR for higher levels of pain 1.15; CI 1.00-1.32) or satisfaction with control of pain during the hospitalization (OR for higher levels of pain 1.12; CI 0.91-1.39), 2 or 6 months after discharge, or during the last 3 days of life. A multifaceted intervention using information, empowerment, advocacy, counseling and feedback was ineffective in ameliorating pain in seriously ill patients. Control of pain in these patients remains an important problem. More intensive pain treatment strategies addressing the needs of seriously ill hospitalized adults must be evaluated.

Aged↗

Age-related changes in aortic sensitivity to noradrenaline and acetylcholine in rats.

1. The purpose of the present study was to determine the relationship between plasma and tissue lipid levels and the effects of age on vascular responses to noradrenaline (NA) and acetylcholine (ACh). 2. Studies were performed in young and aged rats and the response of endothelium-intact and -denuded aortic rings to NA and to ACh was measured. The plasma concentration of cholesterol (total, high-density lipoprotein (HDL) and low-density lipoprotein (LDL)) and 17 beta-oestradiol was determined, as was the aortic tissue content of phospholipids, cGMP and cholesterol (total, free and esterified). 3. Levels of all types of cholesterol in plasma and aorta increased with age; cholesterol levels in plasma correlated with those in the aorta; levels of phospholipid in the aorta did not increase with age but correlated with those of LDL cholesterol in plasma; levels of 17 beta-oestradiol did not change, but those of cGMP increased with age. 4. In endothelium-intact rings, the maximum tension developed by exposure to NA did not change, but the EC50 of NA increased with age and correlated with total cholesterol in the plasma and with the levels of all types of cholesterol in the aorta. In rings precontracted with NA, age decreased the maximum relaxation induced by ACh. The EC50 of ACh decreased with age and was inversely correlated with levels of cholesterol in the plasma and aorta. Treatment with NA increased cGMP levels in aged rats. Removal of the endothelium abolished the response to ACh and heightened the sensitivity to NA in young and aged rats. 5. Aortic endothelial cells seem to inhibit amine-induced contraction, while age-related changes in the levels of cholesterol in aortic tissue affect the sensitivity of the tissue to NA and ACh.

Acetylcholine↗

Phylogenetic relationships among Fagopyrum species revealed by the nucleotide sequences of the ITS region of the nuclear rRNA gene.

The DNA sequences of the internal transcribed spacer (ITS) region of the rRNA gene were determined in 20 taxa of 12 species of Fagopyrum. By comparing the sequence data and constructing phylogenetic trees, the phylogenetic relationships among the Fagopyrum species were established. The sequences of ITS (ITS1 and ITS2) were about 3-7 times more variable than those of the 5.8S subunit of the rRNA gene. The classification of Fagopyrum species based on the DNA sequences of the rRNA gene almost coincides with the classification based on morphology, allozyme variability, and nucleotide sequences of the rbcL-accD region of the chloroplast DNA. A close relationship of F. lineare with the F. statice-F. leptopodum clade was suggested and this was strongly supported by a 68-bp gap in ITS1 found in these three species. A tetraploid F. cymosum from Kathi, India, has two distinct rRNA genes probably on homoeologous chromosomes, and was distinguished from the clade of other diploid/tetraploid F. cymosum with a high bootstrap value. This strengthened the hypothesis of the polyphyletic origin of the tetraploid F. cymosum.

Base Sequence↗

Real-time evaluation of the effectiveness of microwave coagulation therapy for hepatocellular carcinoma using color Doppler imaging.

Percutaneous microwave coagulation therapy (PMCT) is a new technique for the treatment of hepatocellular carcinoma (HCC). However, it is difficult to distinguish those lesions in which necrosis has been induced from the viable residual lesions during the procedure, because the margin of the tumor becomes unclear during PMCT. We determined the area of necrotic lesions during the procedure using color Doppler imaging. PMCT was performed on 10 patients (17 lesions) with recurrent HCC. The electrode of the microwave delivery system was moved around the tumor and the surrounding area until color mosaic images disappeared from the entire area of the tumor. The areas in which necrotic tissue was indicated by color Doppler imaging were later confirmed by other modalities such as angiography or contrast-enhanced computed tomography. This leads us to believe that real-time, effective evaluation of PMCT is possible with color Doppler imaging.

Aged↗

Return to work following injury: the role of economic, social, and job-related factors.

OBJECTIVES: This study examined factors influencing return to work (RTW) following severe fracture to a lower extremity. METHODS: This prospective cohort study followed 312 individuals treated for a lower extremity fracture at 3 level-1 trauma centers. Kaplan-Meier estimates of the proportion of RTW were computed, and a Cox proportional hazards model was used to examine the contribution of multiple risk factors on RTW. RESULTS: Cumulative proportions of RTW at 3, 6, 9, and 12 months post-injury were 0.26, 0.49, 0.60, and 0.72. After accounting for the extent of impairment, characteristics of the patient that correlated with higher rates of RTW included younger age, higher education, higher income, the presence of strong social support, and employment in a white-collar job that was not physically demanding. Receipt of disability compensation had a strong negative effect on RTW. CONCLUSIONS: Despite relatively high rates of recovery, one quarter of persons with lower extremity fractures did not return to work by the end of 1 year. The analysis points to subgroups of individuals who are at high risk of delayed RTW, with implications for interventions at the patient, employer, and policy levels.

Absenteeism↗

Nigral axon terminals are in contact with parvicellular reticular neurons which project to the motor trigeminal nucleus in the rat.

We examined whether in the rat the descending fibers from the substantia nigra pars reticulata (SNr) were in contact with premotor neurons projecting to the motor trigeminal nucleus (Vm), using a combined anterograde and retrograde tracing technique. After ipsilateral injections of cholera toxin B subunit (CTb) into the Vm and biotinylated dextranamine (BDA) into the SNr, numerous CTb-labeled neurons were distributed bilaterally with slightly ipsilateral dominance in the parvicellular reticular formation (RFp), where many BDA-labeled axons with bouton-like varicosities were found bilaterally with a clear-cut ipsilateral dominance. The overlapping distribution of these labeled axons and neurons was more prominent in the rostral RFp than in the caudal RFp. Within the neuropil of the RFp, some of the BDA-labeled axons made synapses with the somata and proximal dendrites of CTb-labeled neurons. Thus, the present study demonstrated the existence of an indirect pathway from the SNr to the Vm, relayed by the RFp.

Animals↗

Enhancement of neurite outgrowth by the soluble form of human L1 (neural cell adhesion molecule).

L1, a neural cell adhesion molecule, is involved in neurite outgrowth, migration and fasciculation. Although L1 is a membrane glycoprotein expressed on neural cells, the soluble form of L1 is generated in vivo by proteolysis. In the present study, a stable transfectant of Chinese hamster ovary (CHO) cells secreting human L1 without cytoplasmic and membrane spanning domains was generated, and the function of the secreted L1 was examined. Explants from embryonic chick brain stem were cultured on a substrate coated with polyethylenimine (PEI) alone, on substrate-bound L1 or in medium containing soluble L1. The neurites induced by L1, both the substrate-bound form and the soluble form, were 2-3 times longer than those cultured on PEI. The ability of the soluble L1 to induce neurite formation was slightly greater than that of the substrate L1. The present results demonstrated that neurite outgrowth was induced not only by substrate-bound L1 but also by soluble L1. Soluble L1 could be a pharmaceutical candidate for the promotion of nerve regeneration.

Animals↗

Early development of the oligodendrocyte in the embryonic chick metencephalon.

It has been demonstrated that the spinal cord oligodendrocytes in the vertebrates arise in the ventral ventricular zone adjacent to the floor plate in their early development. Because of the similarities of basic structures in the spinal cord and metencephalon, it is probable that the mode of early oligodendrocyte development in the metencephalon is the same as that in the spinal cord. We examined this possibility in chick embryos, using monoclonal antibodies O1 and O4, markers for oligodendrocyte lineage. An O4-positive (O4+) cell focus was observed in the medial ventricular zone of E5 chick ventral metencephalon (the earliest stage examined), adjacent to the floor plate. At E6, O4+ cells were dispersed from the medial to the lateral pons and, at E7, to the cerebellar anlagen. O4+ cells in the E6 brainstem and in the E7 cerebellum were unipolar in shape, whereas one day later, some of the labeled cells were multipolar with a few thin processes. O1+ oligodendrocytes first appeared at E8 in the ventromedial part of the pons and were distributed throughout the pons at E10 and in the cerebellum at E12. Explants from three subdivisions of the metencephalon (medial and lateral pons, and cerebellum) from E5 to E8 chick embryos were separately cultured to confirm the potential for generation of oligodendrocyte lineage. O4+ cells appeared in the culture of the E5 medial pons (the earliest stage examined), in the E6 lateral pons, and in the E7 cerebellum. In addition, E7 was the youngest stage from which cerebellar explants were able to generate O1+ oligodendrocytes. Our results clearly demonstrated the in vivo morphology of oligodendrocyte precursors in the metencephalon and their developmental appearance in a ventral-to-dorsal manner. From the bipolar morphology of O4+ cells and the spacio-temporal continuity of the dispersion, it is inferred that the initial dispersion of O4+ cells may involve oligodendrocyte migration from the focus of the medial pons to the lateral and dorsal parts of the metencephalon.

Animals↗

Demonstration of the corticotectobulbar pathway from the orofacial motor cortex to the parvicellular reticular formation in the rat.

We examined a corticotectobulbar pathway from the orofacial motor cortex (OfM) to the parvicellular reticular formation (RFp), where numerous premotor neurons for the orofacial motor nuclei were known to be distributed, light and electron microscopically by using a combination of anterograde and retrograde tracing techniques. After contralateral injections of biotinylated dextranamine (BDA) into the OfM and cholera toxin B subunit (CTb) into the RFp, the overlapping distribution of ipsilateral axon terminals labeled with BDA and contralateral neurons labeled with CTb was found in the lateralmost part of the superior colliculus (SC). Furthermore, contralateral injections of BDA into the OfM and wheat germ agglutinin-horseradish peroxidase (WGA-HRP) into the RFp resulted in that ipsilateral axons labeled with BDA made asymmetrical synaptic contacts with the dendrites of contralateral SC neurons labeled with WGA-HRP.

Animals↗