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Biomedical subjects

K Hayashi

Publications and source records attributed to K Hayashi.

At least 379 records · Page 21Linked to original sources
PubMed2000

The biologic response to laser thermal modification in an in vivo sheep model.

The purpose of this study was to evaluate the effect of nonablative laser energy on mechanical, histologic, ultrastructural, and biochemical properties of joint capsular tissue in an in vivo sheep model. Femoropatellar joint capsule was treated with the holmium:yttrium-aluminum-garnet laser via an arthroscope, and tissues were harvested immediately after surgery, or at 3, 7, 14, 30, 60, 90, and 180 days after surgery (n = 8/group). Laser treatment caused significant decreases in tissue stiffness from 0 to 7 days after surgery, then stiffness gradually increased after 14 days. Tissue strength was lowest 3 days after laser treatment. Histologic examination revealed immediate collagen hyalinization and cell necrosis, followed by active cellular response characterized by extensive fibroblast migration and capillary sprouting. Tissue appeared to be normal histologically 60 days after surgery; however, collagen fibrils remained uniformly small. This study showed an active tissue response secondary to thermal modification with concomitant recovery of mechanical properties by 30 days after surgery. Whether the shrinkage or joint stability was maintained with time remains to be evaluated. To clarify the advantages and disadvantages of this technique, a carefully controlled clinical trial with long term followup should be performed.

Animals↗
PubMed2000

Effects of monopolar radiofrequency energy on ovine joint capsular mechanical properties.

Radiofrequency energy may provide a relatively noninvasive method to stabilize joints with excessive laxity by thermally shrinking redundant joint capsular tissue. The authors determined the percentage of shrinkage associated with five radiofrequency treatment temperatures and evaluated the effect of this energy on the structural properties of joint capsular tissue in vitro. First, 36 adult sheep femoropatellar joint capsular specimens were treated with one of five treatment temperatures (n = 6 per group) or served as a control to determine tissue shrinkage. An additional 24 specimens were treated with three temperatures that resulted in different shrinkage: 45 degrees C, 65 degrees C, and 85 degrees C. Tissue stiffness, relaxation, and failure strength were determined for each specimen (n = 6 per group). Tissue shrinkage was correlated significantly with treatment temperature. There was a significant decrease in tensile stiffness in the 65 degrees C and 85 degrees C treatment groups. There were no significant differences between stress relaxation before treatment and after treatment. Relaxation properties after treatment were not different from each other or from control values either normalized to pretreatment values or expressed as raw data. Failure strength was not affected significantly at any temperature.

Animals↗
PubMed2000

Comparative effects of laser and radiofrequency energy on joint capsule.

The study compared the effects of laser and monopolar radiofrequency energy on thermal and architectural properties of joint capsular tissue in an in vitro ovine model. Sheep glenohumeral joint capsular specimens were treated with laser (5, 10, 15 W) or radiofrequency energy (55 degrees, 65 degrees, 75 degrees C) (n = six per group). Energy application caused significant tissue shrinkage and decreased surface area in all laser and radiofrequency treatment groups. Tissue thickness significantly increased in all treatment groups except for radiofrequency 55 degrees C. Tissue shrinkage, surface area, and thickness each correlated significantly with the delivered laser energy per tissue area or mean radiofrequency probe temperature. There were no significant differences among laser 10 W, laser 15 W, and radiofrequency 75 degrees C treatment groups for these three architectural parameters. Tissue temperature was elevated significantly in the laser 10 W, laser 15 W, radiofrequency 65 degrees C, and radiofrequency 75 degrees C groups when compared with the control. Tissue temperature changes between the laser 10 W and radiofrequency 75 degrees C groups were similar; however, laser treatment produced a steeper temperature increase accompanying its peak temperature. Despite different mechanisms, laser and radiofrequency energy can achieve similar and predictable tissue modification, which is temperature dependent. Additional in vivo studies must be performed to evaluate the applicability of these techniques to clinical use.

Animals↗
PubMed2000

Distinct action of aranidipine and its active metabolite on renal arterioles, with special reference to renal protection.

Aranidipine, a newly developed calcium antagonist, possesses unique pharmacologic characteristics in that its metabolite (M-1) still has antihypertensive action. We examined the effects of both agents on renal microcirculation using the isolated perfused hydronephrotic rat kidney. During norepinephrine-induced constriction, the addition of aranidipine dilated both afferent and efferent arterioles in a dose-dependent manner; at 10(-6) M, 83 +/- 6% and 90 +/- 6% reversal, respectively. In contrast, its active metabolite exerted dilator action predominantly on the afferent arteriole (79 +/- 4% vs. 44 +/- 17% at 10(-6) M for afferent and efferent arterioles, respectively). We further examined the long-term (8 weeks) effect of these agents on the development of renal injury in salt-loaded subtotally nephrectomized spontaneously hypertensive rats. Both aranidipine and M-1 reduced blood pressure by a similar magnitude. The decreases in proteinuria were observed in the aranidipine-treated group at weeks 6, 8, and 10, whereas in the M-1 group, significant reduction was attained only at week 6. Histopathologic examination revealed that both treatments improved glomerular and arteriolar sclerosis. Glomerular sclerosis, however, was less pronounced in the aranidipine-treated group than in the M-1 group. In conclusion, aranidipine has dilator action on both arterioles, whereas M-1 caused predominant dilation of afferent arterioles. Such metabolic changes may constitute a determinant of efferent arteriolar action of the calcium antagonist.

Animals↗
PubMed2000

Effects of stress shielding on the transverse mechanical properties of rabbit patellar tendons.

With the aim of studying mechanisms of the remodeling of tendons and ligaments, the effects of stress shielding on the rabbit patellar tendon were studied by performing tensile and stress relaxation tests in the transverse direction. The tangent modulus, tensile strength, and strain at failure of non-treated, control patellar tendons in the transverse direction were 1272 kPa, 370 kPa, and 40.5 percent, respectively, whereas those of the tendons stress-shielded for 1 week were 299 kPa, 108 kPa, and 40.4 percent, respectively. Stress shielding markedly decreased tangent modulus and tensile strength in the transverse direction, and the decreases were larger than those in the longitudinal direction, which were determined in our previous study. For example, tensile strength in the transverse and longitudinal direction decreased to 29 and 50 percent of each control value, respectively, after 1 week stress shielding. In addition, the stress relaxation in the transverse direction of stress-shielded patellar tendons was much larger than that of nontreated, control ones. In contrast to longitudinal tensile tests for the behavior of collagen, transverse tests reflect the contributions of ground substances such as proteoglycans and mechanical interactions between collagen fibers. Ground substances provide lubrication and spacing between fibers, and also confer viscoelastic properties. Therefore, the results obtained from the present study suggest that ground substance matrix, and interfiber and fiber-matrix interactions have important roles in the remodeling response of tendons to stress.

Animals↗
PubMed2000

Comparison of polymorphism of thymidine kinase gene and restriction fragment length polymorphism of genomic DNA in herpes simplex virus type 1.

The polymorphism of the thymidine kinase (TK) gene of herpes simplex virus type 1 (HSV-1) was analyzed and was compared with the restriction fragment length polymorphism (RFLP) of the whole genome to evaluate the relative efficiency of the TK gene as a potential probe for identification and discrimination of HSV-1. The effectiveness of using the polymorphism of the TK gene in classifying HSV-1 strains was comparable to that of RFLP analysis of 66 sites, suggesting that TK gene sequencing may have important applications in epidemiological studies of HSV-1.

DNA, Viral↗
PubMed2000

Maternal and fetal circulating angiogenin levels in pregnancies with small-for-gestational-Age and appropriate-for-gestational-Age infants.

OBJECTIVE: The objective of the present study was to evaluate whether maternal and fetal circulating angiogenin levels in pregnancies with small-for-gestational- age (SGA) infants are different from those in pregnancies with appropriate-for-gestational-age (AGA) infants. METHODS: Maternal and fetal circulating angiogenin concentrations were compared at birth between 16 pregnancies with SGA (7 delivered vaginally and 9 delivered by elective cesarean section) and 46 pregnancies with AGA (27 delivered vaginally and 19 delivered by cesarean section). Serum angiogenin level was measured with an enzyme-linked immunosorbent assay. RESULTS: There were no significant differences in maternal and fetal serum angiogenin levels between the two groups. However, maternal serum angiogenin levels were significantly higher than those in fetal serum within both SGA and AGA infant pregnancies. There were no significant differences in maternal and fetal serum angiogenin levels between vaginal and cesarean delivered pregnancies in both SGA and AGA groups. CONCLUSION: These results suggest that there is no difference in angiogenin synthesis between SGA and AGA pregnancies.

Adult↗
PubMed2000

Serum angiogenin levels during menstrual cycle and pregnancy.

OBJECTIVE: To evaluate alterations in maternal circulating angiogenin levels with advancing gestation and to assess the effect of labor stress on serum angiogenin levels in neonates delivered vaginally and by cesarean section. METHODS: The maternal circulating angiogenin concentrations were compared in 37 normotensive nonpregnant women, in 60 normotensive pregnant women from 7 to 41 weeks of gestation, and in 12 normotensive postpartum women on the 3rd puerperal day. The serum angiogenin concentrations were also measured in 12 patients with threatened premature labor. Moreover, maternal and fetal serum angiogenin samples before and after delivery were used to determine differences in 12 neonates delivered vaginally and in 11 neonates delivered by elective cesarean section. The serum angiogenin level was measured using an enzyme-linked immunosorbent assay. RESULTS: There was no significant difference in serum angiogenin levels during each phase of the menstrual cycle. The serum angiogenin levels were decreasing until 15 weeks of gestation and increasing thereafter. There was no significant difference in serum angiogenin levels between normal pregnant women and in patients with threatened premature labor. Labor stress did not affect either maternal or fetal serum angiogenin concentrations. The serum angiogenin levels of the neonates were significantly lower than those in maternal serum after both vaginal delivery and delivery by cesarean section. CONCLUSION: These results suggest that regulatory mechanisms of angiogenin may exist during pregnancy.

Cesarean Section↗
PubMed2000

Serum group II phospholipase A(2) levels during menstrual cycle and pregnancy.

The purpose of this study was to evaluate the circulating group II phospholipase A(2) (PLA(2)-II) levels during normal menstrual cycle and to assess alterations in maternal circulating PLA(2)-II concentrations during pregnancy and at puerperium. Circulating serum PLA(2)-II concentrations were compared between 38 nonpregnant women with normal menstrual cycle (15 at menstrual phase, 11 at follicular phase, and 12 at luteal phase), 61 normal pregnant women (13 in the first trimester, 12 in the second trimester, and 36 in the third trimester), and 14 normal postpartum women at 5th puerperal day. Serum PLA(2)-II concentrations were also measured in 11 patients with threatened premature labor. Maternal and fetal serum PLA(2)-II levels before and after delivery were made to determine differences in 11 neonates delivered vaginally and 11 neonates delivered by elective cesarean section. Serum PLA(2)-II level was measured with an immunoradiometric assay. Serum PLA(2)-II concentrations at luteal phase were significantly lower than those at menstrual or follicular phase (p< 0.05). There was no significant difference for PLA(2)-II levels between first trimester and menstrual phase or follicular phase. There were no significant differences among three trimesters during pregnancy. There was no significant difference in serum PLA(2)-II levels between normal pregnant women and patients with threatened premature labor. Labor stress did not affect both maternal and fetal serum PLA(2)-II concentrations. There was also no significant difference for circulating PLA(2)-II levels between maternal and fetal serum. Interestingly, serum PLA(2)-II concentrations in postpartum women were significantly higher than those in normal pregnant women (p<0.05). These results suggest that a regulatory mechanism of PLA(2)-II may exist during the normal menstrual cycle and at puerperium.

Cesarean Section↗
PubMed2000

Sequence analysis and variation of EBNA-1 in Epstein-Barr virus-related herpesvirus of cynomolgus monkey.

OBJECTIVES: The Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1) is an important protein for immortalization and tumorigenesis of infected cells. EBNA-1 gene variants may play a role in tumorigenesis. We determined the nucleotide and amino acid (aa) sequences of EBNA-1 in EBV-related herpesviruses from cynomolgus monkeys (cynomolgus-EBV) which induced malignant lymphomas in its natural host and in rabbits, and compared them with sequences of EBV and other lymphocryptoviruses (LCVs). METHODS: Polymerase chain reaction and direct sequencing methods were performed using extracted DNA from cynomolgus-EBV-infected cell lines. RESULTS: The amino acid sequences of cynomolgus-EBV EBNA-1 from two cell lines (Si-IIA: 588 aa; Ts-B6: 619 aa) which are antigenically cross-reactive to human EBV EBNA-1 showed homology with human EBV (Si-IIA: 53%; Ts-B6: 58%) and other LCVs from baboons (54 and 52%) and rhesus monkeys (60 and 58%), especially in the C-terminal unique domain. Homology of the EBNA-1 sequence between Si-IIA and Ts-B6 was 92%. The sequence difference between EBV and the related LCVs was manifested mainly in the length of the internal repeat 3-corresponding region, which contains serine in the glycine/alanine repeat region of nonhuman LCVs. CONCLUSION: Sequence variation of cynomolgus-EBV EBNA-1 from different cell lines was observed. However, their sequences show a relatively high homology with human EBV and share the common features of EBNA-1 of EBV and other LCVs.

Amino Acid Sequence↗
PubMed2000

CD3+, CD4-, CD8-, TCR alpha beta-, TCR gamma delta+ granular lymphocyte proliferative disorder without lymphocytosis and clinical symptoms.

Granular lymphocyte-proliferative disorder is characterized by a proliferation of large granular lymphocytes (LGLs). It is often associated with neutropenia, rheumatoid arthritis (RA), and pure red cell aplasia (PRCA). Phenotypic analysis has demonstrated that in most cases, the LGLs show a clonal rearrangement of the TCR alpha beta rearrangement. We are reporting a patient with TCR gamma delta LGL proliferation without clinical findings and lymphocytosis. The patient showed an expansion of the CD3+, CD16+, CD56+, and CD57+ LGL populations which involved coexpression of TCR gamma delta with TCR J gamma and J delta 1 gene rearrangement. Autoimmune manifestations, including RA and PRCA, have not appeared and the results of laboratory examinations have not changed for 1 year after the diagnosis.

Aged↗
PubMed2000

Trends in stroke incidence and acute case fatality in a Japanese rural area : the Oyabe study.

BACKGROUND AND PURPOSE: Stroke mortality in Japan has significantly declined during recent decades. To determine the cause of this decrease, we studied the trends in stroke incidence and case fatality within 28 days after stroke in a rural area in Japan. METHODS: We used a population-based registry during 1977-1991 in Oyabe, a rural area in the central part of Japan. The average population aged 25 years and older numbered 32 859 persons. Changes in age-standardized stroke incidence rate were calculated and compared between the 3 periods 1977-1981, 1982-1986, and 1987-1991. The 28-day case fatality rate was evaluated and also compared between the 3 periods by onset year. RESULTS: The total number of strokes was 2068. The age-standardized incidence rate of all strokes decreased during the 15-year period, from 605 to 417 per 100 000 in men and from 476 to 329 per 100 000 in women. A marked decline was found during 1977-1986 but was not apparent during 1987-1991. Moreover, there was an increase in the group aged 75 years and older. The 28-day case fatality rates for all strokes improved from 18.0% to 14.2% in men and from 26.8% to 19.1% in women during the observation period. CONCLUSIONS: These data indicate that declines in the stroke incidence and the 28- day case fatality have been associated with a marked decrease in stroke-related mortality in Japan.

Acute Disease↗
PubMed2000

Neointima formation in a restenosis model is suppressed in midkine-deficient mice.

Neointima formation is a common feature of atherosclerosis and restenosis after balloon angioplasty. To find a new target to suppress neointima formation, we investigated the possible role of midkine (MK), a heparin-binding growth factor with neurotrophic and chemotactic activities, in neointima formation. MK expression increased during neointima formation caused by intraluminal balloon injury of the rat carotid artery. Neointima formation in a restenosis model was strongly suppressed in MK-deficient mice. Continuous administration of MK protein to MK-deficient mice restored neointima formation. Leukocyte recruitment to the vascular walls after injury was markedly decreased in MK-deficient mice. Soluble MK as well as that bound to the substratum induced migration of macrophages in vitro. These results indicate that MK plays a critical role in neointima formation at least in part owing to its ability to mediate leukocyte recruitment.

Angioplasty, Balloon↗
PubMed2000

Protective effect of erdosteine against hypochlorous acid-induced acute lung injury and lipopolysaccharide-induced neutrophilic lung inflammation in mice.

The effect of erdosteine, a mucoactive drug, on hypochlorous acid (HOCl)-induced lung injury, and the lipopolysaccharide (LPS)-induced increase in tumour necrosis factor-alpha (TNF-alpha) production and neutrophil recruitment into the airway, was investigated. Male BALB/c mice were orally administered erdosteine (3-100 mgkg(-1)), ambroxol hydrochloride (ambroxol) (3-30 mgkg(-1)), S-carboxymethyl-L-cysteine (S-CMC) (100-600 mgkg(-1)) or prednisolone (10 mgkg(-1)), 1 h before intratracheal injection of HOCl or LPS. In the HOCl-injected mice, erdosteine markedly suppressed increases in the ratios of lung wet weight to bodyweight and lung dry weight to bodyweight, whereas the other mucoactive drugs ambroxol and S-CMC had little effect. Erdosteine also inhibited the LPS-induced neutrophil influx, although it did not affect the increased level of TNF-alpha in the bronchoalveolar lavage fluid. The results suggest that attenuation of reactive oxygen species and neutrophil recruitment is involved in the clinical efficacy of erdosteine in the treatment of chronic bronchitis.

Administration, Oral↗
PubMed2000

Low molecular weight chitosan prevents the progression of low dose streptozotocin-induced slowly progressive diabetes mellitus in mice.

The present study was designed to clarify the effect of low molecular weight (LMW) chitosan (chitosan lactate, average MW: 20000) on the progression of slowly progressive non-insulin-dependent diabetes mellitus (NIDDM) induced by a single i.p. injection of low dose (100 mg/kg) streptozotocin (STZ) to 8-week-old male ICR mice. The non-fasting serum glucose levels of STZ-treated control mice continued to rise throughout the experimental period until 23 weeks after STZ treatment. The 0.2% or 0.8% chitosan (water solution), given as drinking water from prediabetic stage (2 weeks after STZ treatment), markedly prevented the time course-related rise of serum glucose levels of diabetic mice. In addition, the reduction of relative numbers of insulin-immunoreactive cells (beta-cells) in the islets of diabetic mice at 24 weeks after STZ treatment was markedly prevented by 0.2% or 0.8% chitosan administration. However, the progression of hyperglycemia in diabetic mice was not affected by 0.2% glucosamine, a monosaccharide of chitosan. The glucose levels of normal mice were not affected by 0.8% chitosan administration. When 0.2% chitosan administration was stopped at 20 weeks, these animals had still maintained significantly lower serum glucose levels, compared to control animals, even at 5 weeks after stopping the administration. These results indicate that LMW chitosan prevents the progression of low dose STZ-induced slowly progressive NIDDM.

Administration, Oral↗
PubMed2000

Differential effects of menopause and metabolic disease on trabecular and cortical bone assessed by peripheral quantitative computed tomography (pQCT).

The usefulness of peripheral quantitative computed tomography (pQCT) was investigated in the diagnosis of metabolic bone diseases, including osteoporosis, and especially in the different diagnostic values in trabecular and cortical components. The subjects were 460 Japanese women aged 20-86 years, including 318 healthy volunteers, 58 osteoporotics with fracture and 84 patients with diseases including amenorrhoea, steroid-induced osteoporosis, renal osteodystrophy (ROD) and primary hyperparathyroidism. Bone mineral density (BMD) was measured for more than 4 years in 74 of the healthy volunteers. BMD was measured by spinal QCT, dual X-ray absorptiometry (DXA) of the spine, radius, and heel, and pQCT of the radius and tibia. High resolution images were obtained for geometry of the radius. Radial pQCT showed a higher correlation with radial DXA than with spinal QCT, and spinal QCT showed a higher correlation with spinal DXA than with radial pQCT. The annual bone loss rates at predominantly trabecular bone sites were accelerated in both the axial and appendicular skeleton. In the fracture study, radial pQCT showed a higher odds ratio (OR = 4.4) than radial DXA, and cortical area ratio seemed to be a good predictor of fracture risk (OR = 5.2). Amenorrhoea and steroid-induced osteoporosis predominantly affected trabecular bone, ROD predominantly affected cortical bone and hyperparathyroidism affected both components, especially the cortical component. pQCT is useful for assessing both trabecular and cortical bone, to provide information on individual bone changes in metabolic bone disease and to estimate the risk of fracture.

Absorptiometry, Photon↗