Search PubMed⌕ Search

Biomedical subjects

H Yagi

Publications and source records attributed to H Yagi.

At least 109 records · Page 6Linked to original sources
PubMed1998

Spontaneous and artificial lesions of magnocellular reticular formation of brainstem deteriorate avoidance learning in senescence-accelerated mouse SAM.

The role of the magnocellular reticular formation (MGRF) of the brainstem on learning and memory was examined in memory-deficient mice with spontaneous spongy degeneration in the brainstem (senescence-accelerated mouse, SAMP8) and control mice (accelerated-senescence resistant mouse, SAMR 1). SAMP8 showed spontaneous age-related impairment of learning and memory, as determined by passive and active avoidance responses. The deficits of learning and memory function in passive avoidance performances began at two months of age and increased with ageing. In the brains of SAMP8 at one month of age and older, spongy degeneration was mainly observed in the brainstem, while no vacuoles were evident in SAMR1 control (normal ageing mouse) brains in the age range tested (up to 12 months). The vacuolization in SAMP8 was marked in the MGRF, especially in the dorsomedial MGRF. Quantitative analysis of the vacuolization showed that the total area and number of vacuoles in the MGRF increased with age, and they were affected by the degree of deficits in learning and memory. The latency 24 h after footshock in passive avoidance tests decreased with the increase in total area and number of vacuoles in MGRF. The number of shocks in active avoidance tests increased with the increase in total number and area of vacuoles. Thus, learning and memory ability in passive and active avoidance responses deteriorated with enlargement in the vacuolated area in MGRF, and it was assumed that MGRF (especially, the dorsomedial part) possesses functions related to learning and memory. To confirm this notion, behavior and memory tests (passive avoidance and active avoidance tests, open field tests and shock sensitivity measurements) were carried out in SAMR1 mice, whose bilateral dorsomedial MGRF was destroyed electrolytically (MGRF-lesioned mice). The MGRF-lesioned mice showed no difference from sham mice in sensory threshold or open field activity; however, there was severe deterioration in passive avoidance behavior and impairment in the active avoidance performances. From the results in SAMP8 and MGRF-lesioned mice, it was confirmed that MGRF (especially the dorsomedial part) has functions related to learning and memory, and is one part in the learning and memory system of the brain. Thus, SAMP8 can serve as a model of RF-lesioned mice with impaired learning and memory functions.

Aging↗
PubMed1998

Influence of altered loading conditions on left atrial appendage function in vivo.

This study sought to examine the influence of heart failure treatment on left atrial (LA) appendage function in 10 patients with left ventricular dysfunction. After treatment of heart failure, LA appendage function markedly improved, less dependent on LA and left ventricular functions, which suggests that with altered loading conditions, LA appendage function changes chiefly through its intrinsic contractile property.

Aged↗
PubMed1998

Cross-reactivity in murine fluoroquinolone photoallergy: exclusive usage of TCR Vbeta13 by immune T cells that recognize fluoroquinolone-photomodified cells.

Fluoroquinolone antibacterial agents are well known to elicit photosensitivity as an adverse effect, and their cross-reactivity has been clinically documented. The photoallergenicity of fluoroquinolones is mainly derived from their photohaptenic moiety, and photomodification of skin epidermal cells with fluoroquinolones is thought to be an initial step for this photoallergy. Here we have explored, both in vivo and in vitro, T cell responses to fluoroquinolone-photomodified cells, focusing on their photoantigenic cross-reactivity. Cells were derivatized with fluoroquinolones under exposure to UV-A, and fluoroquinolone photoadducts were detected in photomodified cells by immunostaining, flow cytometry, and cell ELISA using fluoroquinolone-specific mAb. T cell-mediated hypersensitivity induced and elicited by s.c. injection of fluoroquinolone-photomodified epidermal cells was cross-reactive among six fluoroquinolones. In addition, lymph node cells from mice sensitized with fluoroquinolone-photomodified cells proliferated well in vitro not only to Langerhans cell-enriched epidermal cells photoderivatized with corresponding fluoroquinolone, but also to those photomodified with any of five other fluoroquinolones, supporting their cross-reactivity. In three fluoroquinolones tested, Th1 populations that expanded after in vitro photoantigenic stimulation of immune lymph node cells expressed the same Vbeta13 of TCR. The sensitivity could be transferred by the i.v. administration of this Vbeta13+ T cell line into naive recipients, in which a high percentage of Vbeta13+ cells infiltrated at the challenge site. These findings suggest that these fluoroquinolones carry the same photoantigenic epitope, which is recognized by Vbeta13+ T cells, leading to fluoroquinolone photosensitivity and cross-reactivity.

Adoptive Transfer↗
PubMed1998

Regulation of peripheral blood mononuclear cell responses to Dermatophagoides farinae by substance P in patients with atopic dermatitis.

Neuropeptides mediate stress-induced cutaneous inflammation such as atopic dermatitis. The effect of substance P on proliferation and cytokine mRNA expression of peripheral blood mononuclear cells in response to Dermatophagoides farinae (Der f) was studied in atopic dermatitis patients with positive RAST scores to Der f. Upon stimulation with Der f peripheral blood mononuclear cells from patients proliferated in a B7-dependent (CD80- and CD86-dependent) manner, while those from the patients with negative scores, nonatopic eczematous dermatitis patients or normal individuals, did not. Based on the reactivity of normal individuals, atopic dermatitis patients with a stimulation index greater than 1.8 were tentatively defined as high responders, who comprised two-thirds of the patients. Proliferation in high responders was associated with upregulation of IL-2 mRNA expression and induction of IL-5 mRNA expression. Substance p at 10(-10) to 10(-8) M promoted the Der f-induced proliferation when added at the start of culture and upregulated IL-10 MRNA expression while downregulating IL-5 mRNA expression. Our results suggest that substance P modifies immune responses of atopic T cells to Der f by promoting proliferation and altering cytokine profiles, and thus modulates the clinical manifestations of atopic dermatitis.

Adolescent↗
PubMed1998

Bullous systemic lupus erythematosus: detection of antibodies against noncollagenous domain of type VII collagen.

A 9-year-old girl with systemic lupus erythematosus developed bullous eruption. Histopathologic examination showed subepidermal blistering and immunoglobulins (IgG, IgM, IgA) and complement components (C1q, C3) deposited linearly at the basement membrane zone. IgG in this patient's serum bound to the dermal side of 1 mol/L sodium chloride-split normal human skin, and a 290 kd protein was identified in the dermal extract. The patient's serum recognized various epitopes on the noncollagenous domain as demonstrated by the use of fusion proteins of type VII collagen. Resolution of the bullous eruption occurred after treatment with dapsone.

Antimetabolites↗
PubMed1998

Reversible left atrial dysfunction possibly due to afterload mismatch in patients with left ventricular dysfunction.

Limited data are available concerning the influence of altered loading conditions on left atrial (LA) function. In addition, the underlying mechanism of the augmentation of atrial filling (A) velocity (assessed by transmitral Doppler measurement) after treatment of heart failure has been less studied. Therefore, we examined various indexes of LA function during the depression of left ventricular (LV) filling pressure resulting from treatment of heart failure. Twelve patients with LV dysfunction (ejection fraction < 50%) underwent right heart catheterization and transthoracic echocardiography before and after optimal treatment of heart failure. LV/LA volume and ejection fraction and mitral and pulmonary venous flow velocities were measured. LV stiffness (substitute for LA afterload) was assessed by the ratio of LV filling pressure to LV end-diastolic volume. After treatment of heart failure, the mitral A velocity significantly increased (38 +/- 9 to 58 +/- 16 cm/sec, p < 0.005) and there was a distinct attenuation of the difference of the pulmonary venous and mitral A-wave duration (43 +/- 29 to -8 +/- 31 msec, p < 0.005). These findings were associated with a marked decrease in LV stiffness (0.12 +/- 0.04 to 0.05 +/- 0.02 mm Hg/ml, p = 0.0001) and an increase in LA ejection fraction (27% +/- 7% to 38% +/- 8%, p < 0.005). There was a significant curvilinear relation between LA ejection fraction and LV stiffness (r = 0.63, p < 0.01). The mitral A velocity correlated positively with LA ejection fraction (r = 0.77, p < 0.0001) and inversely with LV stiffness (r = -0.52, p < 0.01). The reversible LA dysfunction suggests that the initial LA dysfunction is due to LA afterload mismatch rather than intrinsic LA disease, which also contributes to the augmentation of the mitral A velocity after heart failure treatment.

Atrial Function, Left↗
PubMed1998

Placental ecto-ATP diphosphohydrolase: its structural feature distinct from CD39, localization and inhibition on shear-induced platelet aggregation.

Human placental ecto-ATP diphosphohydrolase (ATPDase), an 82 kDa single-chain glycoprotein, was purified to high specific activity using a specific murine monoclonal antibody MK33 (IgG1-kappa). Structurally, protein-based analysis showed this enzyme to be almost identical to that of CD39 lymphoid cell activation antigen deduced by cDNA sequencing (Maliszewski CR, et al, J Immunol 1994; 153:3574); but differing in the NH2-terminal amino acid sequence, suggesting that placental ecto-ATPDase is most likely an isoform of CD39 generated by alternative splicing of the pre-mRNA. Functionally, placental ecto-ATPDase totally inhibits the secondary platelet aggregation induced by agonists at a final concentration (f.c.) of 1 microgram/ml. The purified enzyme (1 microgram/ml, final), pre-incubated with washed platelets prior to alpha-thrombin stimulation, completely inhibits the activation of platelet glycoprotein (GP) IIb/IIIa, thereby blocking the binding of fibrinogen or von Willebrand factor to platelets. Further, under different shear stresses, the enzyme modulates platelet aggregation differently. Low shear stress-induced platelet aggregation is blocked by this enzyme in a dose-dependent manner and is totally blocked at f.c. 0.5 microgram/ml. Under high shear stress, however, this protein at a f.c. of 0.5 microgram/ml mediates almost complete disaggregation of platelets without affecting the initial aggregation. Using immunohistochemical analysis, this enzyme was observed to be localized at the syncytiotrophoblasts of placental microvilli and the endothelial cells (ECs) of the umbilical vein obtained at full-term normal delivery, but scarcely at the ECs of the umbilical artery.

Adenosine Triphosphatases↗
PubMed1998

Halide effects in the hydrolysis reactions of (+/-)-7beta, 8alpha-dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo- [a]pyrene.

Rates of reaction of (+/-)-7beta,8alpha-dihydroxy-9alpha, 10alpha-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (DE-2) have been determined in 1:9 dioxane-water solutions containing 1.0 M KCl, 0.5 M KBr, and 0.1 M NaI over the pH range 4-13. These pH-rate profiles are more complicated than those for reaction of DE-2 in 0.2 M NaClO4 solutions and are interpreted in part by mechanisms in which halide ion attacks the diol epoxide as a nucleophile at intermediate pH, resulting in the formation of a trans-halohydrin. Reaction of DE-2 in these halide solutions at pH < ca. 5 occurs by rate-limiting carbocation formation, followed by capture of the intermediate carbocation by halide ion. The relative magnitudes of the rate constants for reaction of the intermediate carbocation with halide ions are estimated from product studies. The halohydrins are unstable intermediates and react quickly in subsequent reactions to yield tetrols in a ratio different than that formed from reaction of the carbocation with solvent. Nucleophilic attacks of 1.0 M Cl-, 0.5 M Br-, and 0.1 M I- on DE-2 are the principal reactions in the pH range ca. 6-9, leading to intermediate trans-halohydrins that hydrolyze to tetrols. At pH ca. 9-11, halohydrin formed from attack of halide ion on DE-2 reverts back to epoxide, leading to a negative break in the pH-rate profile. The main product-forming reaction of DE-2 at pH 11.3 is the spontaneous reaction. At pH > 12, the rate of reaction of DE-2 increases due to a second-order reaction of HO- with DE-2.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1998

A study of growth pattern in giant condyloma acuminatum.

We report a case of giant condyloma acuminatum (CA) of the perianal region. Pathological diagnosis revealed a typical CA with no sign of atypia. In addition, HPV type 11 could be identified by Southern blot analysis. PCNA was highly positive immunohistochemically, but the positivity of p53 protein was not as high as compared with the other control cases. Thus, the high growth rate of tumor cells evaluated by PCNA staining seems to contribute to the marked increase in size, and not only the p53 mutation but also an other cascade may be implicated in cell proliferation.

Adult↗
PubMed1998

Effects of high atmospheric pressure and oxygen on middle cerebral blood flow velocity in humans measured by transcranial Doppler.

BACKGROUND AND PURPOSE: There are several reports that have studied the effects of hyperbaric oxygen (HBO) on cerebral blood flow (CBF). However, most of the reports have been of animal experiments, and human studies are few so far. The aim of this study is to clarify the relationship between HBO and CBF in humans. METHODS: Middle cerebral arterial blood flow velocity (MCV) was measured using transcranial Doppler (TCD) technique in a multiplace hyperbaric chamber. The Doppler probe was fixed on the temporal region by a head belt, and the transcutaneous gas measurement apparatus (tcPO2 and tcPCO2) was fixed on the chest wall. MCV and transcutaneous gas were measured continuously in eight healthy volunteers under four various conditions: 1 atmosphere absolute (ATA) air, 1 ATA oxygen (O2), 2 ATA air, and 2 ATA O2. On the next step, the effect of environmental pressure was studied in another eight healthy volunteers, in whom the tcPO2 was kept at almost the same level under conditions of both 1 ATA and 4 ATA by inhaling oxygen at 1 ATA. RESULTS: MCV of 1 ATA O2, 2 ATA air, and 2 ATA O2 decreased, and tcPO2 increased significantly in comparison with that of 1 ATA air. A significant difference in MCV was observed between the O2 group and the air group under the same pressure circumstance. On the other hand, there were no differences in MCV or tcPO2 between 4 ATA air and 1 ATA plus O2, and the influence for the MCV of the environmental pressure was not observed. CONCLUSIONS: We conclude that hyperoxemia caused by HBO reduces the CBF, but the high atmospheric pressure per se does not influence the CBF in humans.

Adult↗
PubMed1998

Effects of repeated hand instrumentation on the marginal portion of a cast gold crown.

A study was conducted to evaluate the effects of repeated hand instrumentation on the marginal portion of a cast gold crown. Seven extracted periodontally diseased premolars were used. The finishing line of the preparation was placed on the root surface and then the crown was cast and cemented in the usual manner. One proximal surface of each sample was divided into 2 areas: root planing (RP) area and RP plus polishing (RPP) area. The marginal portion of the crown was measured to give a baseline value using a surface roughness- and profile-analyzing system. Then, the marginal portion was painted with a waterproof pen. RP was performed to remove paint in the RP area with the curets. In the RPP area, RP followed by polishing was done by silicone polishing points and a rubber cup with polishing paste. The relevant procedures and measurements were repeated 3 times in each area. Changes in the sample roughness and profile were evaluated and compared between the 2 techniques. The results showed that repeated instrumentation altered the surface of the marginal portion of the cast gold crown, resulting in increased roughness in both areas (P < 0.01). However, the roughness of the RPP area was considerably restored to the baseline value by polishing after RP. Therefore, it is suggested that polishing after RP smoothes the marginal portion of the cast gold crowns and appears to be an efficient prophylactic system.

Bicuspid↗
PubMed1998

Age-related changes in blood pressure in the senescence-accelerated mouse (SAM): aged SAMP1 mice manifest hypertensive vascular disease.

Age-related changes in systolic blood pressure were assessed, using the senescence-accelerated mouse (SAM) model for aging research with strains SAMR1, SAMP1, and SAMP8. Each of the strains manifested a characteristic change in blood pressure with age. The SAMR1 strain, with normal aging, did not have chronologic changes from 2 to 27 months of age. The SAMP1 strain, with accelerated senescence, had a significant increase in blood pressure with age, and some (8 of 39) mice manifested hypertensive vascular disease characterized by high blood pressure, cardiac hypertrophy, and arteriolar fibrinoid necrosis at 11 to 14 months of age. The gradual increase in blood pressure after 8 to 10 months was considered to be preceded by progressive renal changes, from glomerulonephritis to contraction of the kidney, suggesting that the high blood pressure in the SAMP1 strain was of renal origin. Blood pressure in the SAMP8 strain, with age-related deficits in learning and memory, gradually decreased after 5 to 7 months of age, and was suggested to be due to the astrogliotic changes in response to spongiform degeneration in the medulla oblongata at 11 to 14 and 15 to 18 months of age.

Aging↗
PubMed1998

[An experience with St. Jude medical prosthetic 19A-HP which resulted in restricted opening at an early stage after operation].

St. Jude medical hemodynamic plus series is positively used for aortic valve replacement (AVR) of small orifice because it can increase the orifice area by 26% compared with conventional prosthetic valves of the same size. We performed AVR with SJM 19A-HP on a patient having aortic stenosis with regurgitation using horizontal mattress suturing technique. The aortic orifice size was 18.9 mm at the preoperative measurement. The course after the operation was uneventful until 9 days after the operation when cinefluoroscopy revealed symmetrical restriction of opening of valve leaflets. We are now monitoring the clinical course at the patient has not developed any symptoms though the LV-Ao pressures gradient is 60 mmHg by Doppler echocardiography. As the restriction of valve leaflet opening was symmetrical, it is not likely that an excess of the ligature or remnant caused the restriction; structural problems of St. Jude medical prosthesis appear to be a more reasonable explanation. Since the orifice ring of this prosthesis is not reinforced, longitudinal forces applied to the hinge may alter the shape of the ring, thus restricting the movement of valve leaflets. In the present case, forced insertion of 19A-HP instead of more desirable 17-HP is considered to have caused longitudinal forces acting on the hinge.

Aged↗
PubMed1997

N-acyl amino acid biosynthesis in marine bacterium, Deleya marina.

We reported previously that the marine bacterium, Deleya marina (ATCC 25374), produced N-acyl leucine and isoleucine, in which nonhydroxy fatty acid was linked to alpha-amino group of amino acid. Further analysis of bacterium lipids revealed the additional production of N-acyl ornithine. The N-acyl ornithine had a 3-hydroxy fatty acid linked by an amide bond to a-amino group of ornithine and a nonhydroxy fatty acid esterified to the hydroxy group of the 3-hydroxy fatty acid. N-acyl ornithine was located in the cell membrane and N-acyl leucine and isoleucine in cytoplasm. N-acyl ornithine is thought to be a functional analogue of phosphatidylethanolamine (PE) because of their similar structure. PE replacement into N-acyl ornithine in the cell membrane under phosphate-limited conditions was observed with other bacteria, so we anticipated the nonbiosynthesis of N-acyl ornithine under phosphate-sufficient conditions. We did not anticipate that N-acyl leucine and isoleucine in cytoplasm, whose structure is dissimilar to that of PE, would be replaced into PE in the cell membrane. Neither N-acyl leucine, N-acyl isoleucine, nor N-acyl ornithine was biosynthesized under phosphate-sufficient condition. Thus, we report here for the first time that N-acyl amino acids in cytoplasm were not biosynthesized under phosphate-sufficient conditions.

Bacteria↗
PubMed1997

Spontaneous hair follicle cycling may influence the development of murine contact photosensitivity by modulating keratinocyte cytokine production.

The development of murine contact hypersensitivity is influenced by hair follicle cycling. Here, we have examined hair cycle-associated fluctuations of murine contact photosensitivity (CPS) to tetrachlorosalicylanilide (TCSA) and its immunologic mechanism(s). When the CPS outcome was monitored in correlation with their spontaneous, synchronized hair cycling, mice aged 8 and 14 weeks, with most of their hair follicles in telogen, exhibited strong CPS responses, whereas 4-, 11-, and 16-week-old mice with a predominance of anagen follicles in a large area of their integument exhibited lower responses. This suggests that the development of CPS is inhibited in mice with anagen hair follicles. Antigen-specific, T-cell receptor V beta 7+ suppressor T cells, which are recognized to down-regulate the CPS response to TCSA, were not generated in sensitized anagen mice. Culture supernatants of epidermal cells derived from mice with anagen hair follicles contained factor(s) that suppress in vivo the development of CPS. It was found that levels of mRNA for tumor necrosis factor alpha (TNF alpha) were markedly decreased in epidermal cells from early anagen to telogen mice, whereas message for IL-1 receptor antagonist (IL-1ra) was transcribed increasingly during this hair cycling. These findings suggest that altered keratinocyte production of these cytokines is involved in mediating the anagen-associated depression of CPS.

Age Factors↗
PubMed1997

Targeted disruption of Cbfa1 results in a complete lack of bone formation owing to maturational arrest of osteoblasts.

A transcription factor, Cbfa1, which belongs to the runt-domain gene family, is expressed restrictively in fetal development. To elucidate the function of Cbfa1, we generated mice with a mutated Cbfa1 locus. Mice with a homozygous mutation in Cbfa1 died just after birth without breathing. Examination of their skeletal systems showed a complete lack of ossification. Although immature osteoblasts, which expressed alkaline phophatase weakly but not Osteopontin and Osteocalcin, and a few immature osteoclasts appeared at the perichondrial region, neither vascular nor mesenchymal cell invasion was observed in the cartilage. Therefore, our data suggest that both intramembranous and endochondral ossification were completely blocked, owing to the maturational arrest of osteoblasts in the mutant mice, and demonstrate that Cbfa1 plays an essential role in osteogenesis.

Animals↗