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Biomedical subjects

T Kubo

Publications and source records attributed to T Kubo.

At least 325 records · Page 18Linked to original sources

Long-term effects of hyaluronan on experimental osteoarthritis in the rabbit knee.

OBJECTIVE: Long-term assessment of the effect of hyaluronan (HA) on the articular cartilage and synovium in an animal knee joint during the development of osteoarthritis (OA). DESIGN: Sixty mature New Zealand white rabbits underwent unilateral anterior cruciate ligament transection (ACLT) and were divided into two groups. Group 1 (SA) received intra-articular injections of 0.3 ml hyaluronan (HA) (i.e., ARTZ, MW: 8 x 10(5)) beginning 4 weeks after ACLT, once a week for 5 weeks. Group 2 (SV) received injections of the vehicle (phosphate buffered saline) in the same fashion as with the SA group. The contralateral nonoperated knee served as control. All animals were killed 21 weeks after surgery and their knee joints evaluated by gross morphologic, histologic, histomorphometric and biochemical analyses. RESULTS: Gross morphological inspection indicated that the femoral condyles from the knees injected with vehicle suffered more severe cartilage damage than cartilage from the knees injected with HA. Furthermore, two out of three histomorphometric parameters measured in the HA-treated cartilage (i.e., cartilage thickness and cartilage area which were not statistically different than control) provided evidence showing a protective effect of HA on the femoral condyles following ACLT. Biochemical analysis showed articular cartilage remaining on the femoral condyles following ACLT to have similar characteristics to contralateral controls. However, DNA concentration in the synovium from the ACLT knees of the vehicle-treated animals was greater than contralateral control, while this parameter was not statistically different than contralateral control in the HA treated animals. CONCLUSIONS: These results demonstrate a protective effect of HA on preservation of the articulating surface of the femoral condyle following ACLT up to 21 weeks post-surgery.

Animals↗

Differences in the repair process of longitudinal and transverse injuries of cartilage in the rat knee.

OBJECTIVE: To clarify the relationship between type or direction of cartilage injury and its repair process, we investigated defects produced in rat knees histologically, immunohistochemically, and histomorphometrically. METHODS: A full-thickness cartilage injury (1 mm wide and 5 mm long) was produced on the patellar groove of one knee (L-injury) and transversely on the other knee (T-injury) in 42 male Wistar rats. Six rats each were sacrificed at 1, 2, 3, 4, 6 and 8 weeks after surgery, and cartilage tissues were obtained, prepared into 4 microns-thick histologic specimens, and stained with hematoxylin and eosin. Cartilage thickness, cartilage area, and surface roughness were measured using a computer system. Localization of S-100 proteins was evaluated with immunohistochemistry. RESULTS: Grossly, there were no difference in repair process between L- and T-injuries. However, histological and histomorphometric differences became apparent after the third week: cartilage thickness, repair area, and surface roughness showed better recovery in L-injury than in T-injury. Appearance of S-100-positive protein preceded the appearance of chondrocytes, and L-injury presented S-100 in the entire defect while S-100 in T-injury appeared mainly on the margins of the defect. CONCLUSIONS: Repair mechanisms of cartilage injury differs according to injury direction. Better repair can be obtained in the injury which is parallel to the direction of joint motion.

Animals↗

Image analysis of the human inner ear.

The KS 300 is a multifunctional software image analysis system using an object-oriented programming environment. The possibility of its application for the inner ear was studied by using specimens from humans and squirrel monkeys, immunostained for the brain-derived calcium-binding protein, S-100 protein. Grey images were used for measurements. The cell borders were outlined by hand, using a digitizer. The absolute grey values of the pixels changed when the brightness of the images or other conditions changed. By contrast, the relative grey values, i.e. the absolute grey values correlated to the mean grey values of the histoimage, remained constant. By utilizing these relative grey values, it was possible to compare cells both between different specimens and between different areas within the same specimen. The different grey values of spiral ganglion cells stained for S-100 protein are objective quantitative measurements and are believed to reflect differences in their function. In some regions of both human and squirrel monkey specimens, relatively intensely stained cells predominated, whereas in other regions, relatively weakly stained cells were mainly observed. Thus, our image analysis system using the relative grey values has proved suitable for quantitative analysis of immunostained specimens in order to compare them and to assess cell function.

Adult↗

Histaminergic influence on vestibular stimulation-induced locus coeruleus inhibition in rats.

In previous reports we have shown that caloric stimulation (CS) of the vestibular apparatus inhibits locus coeruleus (LC)-noradrenergic neuronal activity in urethane-anaesthetized rats. The present study examined the effect of neural histamine depletion by alpha-fluoromethylhistidine (alpha-FMH) on CS-induced LC inhibition. In alpha-FMH treated rats, LC neuronal inhibition caused by CS was still observed. This finding indicates that the central histaminergic neuron system does not participate in the CS-induced LC-noradrenergic inhibition. It is suggested that the noradrenergic neuron system is involved in the development of vestibulo-autonomic response, independent of the histaminergic neuron system.

Animals↗

An implication of protein phosphatase 2A-beta in the rat flocculus for lesion-induced vestibular plasticity.

The differential display method was applied to identify genes, the expression of which is up-regulated in the cerebellar flocculus after unilateral labyrinthectomy (UL). Total RNA from sham-operated and labyrinthectomized rat flocculi was isolated, amplified by polymerase chain reaction (PCR) using a single arbitrary primer and separated by electrophoresis on a polyacrylamide gel. PCR products in amounts significantly higher in samples from labyrinthectomized animals than in those from controls were cut out of the gel and sequenced. One of the cDNA fragments showed 100% nucleotide sequence identity to the rat protein phosphatase 2A (PP2A)-beta catalytic subunit mRNA. In situ hybridization histochemistry and Northern blot analysis showed that PP2A-beta mRNA expression was intensely localized to the floccular Purkinje cell layer and up-regulated with a maximum increase within 2 days after UL. In labyrinthectomized rats, UL-induced nystagmus gradually disappeared within 3 days after UL. However, in animals with continuous floccular infusion of okadaic acid, a potent inhibitor of PP2A, UL-induced nystagmus lasted significantly longer. All these findings suggest that up-regulation of PP2A-beta mRNA in floccular Purkinje cells after UL is involved in lesion-induced vestibular plasticity. So far, various kinds of neural plasticity-associated molecules have been investigated mainly by slice in vitro studies. This paper indicates that differential display is the feasible molecular biological in vivo method for an investigation about the mechanism of neural plasticity.

Animals↗

Correlation of epidermal growth factor receptor and radiosensitivity in human maxillary carcinoma cell lines.

To determine the relationship between epidermal growth factor receptor (EGFR) and radiosensitivity, we immunostained cells from three maxillary carcinoma cell lines with an anti-EGFR antibody. The intensity of staining reactivity, determined by means of an image analysis system, was expressed as grey value (0-black to 255-white). The mean grey values for cell lines IMC-2, IMC-3, and IMC-4 were 181, 210, and 222, respectively, and differed significantly (p < 0.001). This indicates that IMC-2 had the highest number of EGFR, followed by IMC-3 and IMC-4. The cells were then irradiated at 1, 2, 4, or 6 Gy, and cell survival was assessed by means of a standard colony-forming assay. IMC-2 had the highest survival rates at 1, 2 and 4 Gy, followed by IMC-3 and IMC-4. Therefore, the survival rates for IMC-2, IMC-3, and IMC-4 after irradiation increased in proportion to the amount of EGFR in each cell line. These results support the findings of previous clinical studies which showed that increased expression of EGFR was associated with higher recurrence rates of glottic and maxillary sinus carcinoma in patients treated with radiation therapy. The amount of EGFR in cells may therefore be associated with their radiosensitivity.

Carcinoma, Squamous Cell↗

Endogenous insulin-like growth factor-I is obligatory for stimulation of rat inhibin alpha-subunit expression by follicle-stimulating hormone.

Insulin-like growth factor-I (IGF-I) is essential for FSH-dependent steroidogenesis by rat granulosa cells (GC), but whether IGF-I is required for other FSH-dependent functions is unknown. To investigate the role of IGF-I in the mechanisms of FSH-stimulated inhibin alpha-subunit (Inh-alpha) production, rat GC were cultured with FSH, IGF-I, insulin-like growth factor-binding protein (IGFBP)-4, IGFBP-5, and/or anti-IGF-I antibody. Inh-alpha protein and mRNA levels were measured in conditioned medium and cells by Western immunoblotting and Northern analysis, respectively. Inh-alpha expression was increased by FSH (3.5-fold) and IGF-I (2.5-fold), and the effects were dose and time dependent. FSH stimulation of Inh-alpha was attenuated by IGFBP-4 or -5 in a dose-dependent fashion, and the effects were reversed by IGF-I. Anti-IGF-I antibody mimicked the inhibitory effects of IGFBP-4 and -5. Forskolin, cholera toxin, and 8-bromo-cAMP increased Inh-alpha production approximately 3.5-fold, and the effects were blocked by IGFBP-4 or -5. Increases in Inh-alpha by FSH, IGF-I, forskolin, cholera toxin, and 8-bromo-cAMP were totally blocked by the protein tyrosine kinase inhibitor, tyrphostin A23. In summary, these results suggest that the stimulation of Inh-alpha expression by FSH requires activation of protein tyrosine kinases by endogenously produced IGF-I. We propose that the IGF-I signaling is obligatory for FSH stimulation of Inh-alpha expression in rat GC.

8-Bromo Cyclic Adenosine Monophosphate↗

Activin-induced inhibin alpha-subunit production by rat granulosa cells requires endogenous insulin-like growth factor-I.

Inhibin-alpha subunit (Inh-alpha) gene expression is important for granulosa cell (GC) differentiation and prevention of ovarian tumorigenesis. Studies on Inh-alpha regulation have implicated activin and insulin-like growth factor-I (IGF-I) in the mechanisms of expression. Here we present evidence that endogenously produced IGF-I plays an obligatory role in activin-induced Inh-alpha production. Primary cultures of rat GC were incubated with increasing concentrations of various regulatory molecules, and the levels of Inh-alpha protein and its mRNA were measured in conditioned medium and cells, respectively. Recombinant activin A stimulated Inh-alpha expression, and the effects were dose- and time-dependent. The receptor tyrosine kinase inhibitor tyrphostin A23 caused a dose-dependent inhibition of activin-dependent Inh-alpha expression, whereas the inactive isomer, A63, had no effect. The stimulatory effect of activin was also blocked in a dose-dependent manner by added IGF binding protein-4 or -5, and the effects were reversed by IGF-I. Moreover, increasing concentrations of an anti-IGF-I antibody had a similar inhibitory effect on activin-stimulated Inh-alpha expression. Collectively, these results suggest, for the first time, that endogenously produced IGF-I is required for activin stimulation of Inh-alpha expression in cultured rat GC.

Activins↗

Effects of follicle-stimulating hormone on endothelin receptors in cultured rat ovarian granulosa cells.

Two subtypes of the endothelin (ET) receptor (ETA and ETB) were studied in cultured ovarian granulosa cells. Immature 21-day-old female Wistar-Imamichi rats were implanted with diethylstilbestrol (DES) pellets for 5 days and granulosa cells were collected by repeated puncturing. Viable cells (2.5 or 5 x 10(5)) were cultured with 50--400 ng/ml of ovine NIH follicle-stimulating hormone (FSH) in the presence or absence of [125I-Tyr13]ET-1 (50 pM) in 1 ml McCoy's 5a medium for 72 h. FSH gradually increased the [125I-Tyr13]ET-1 binding to granulosa cells, whereas FSH-untreated granulosa cells had no significant changes. The dose of 200 ng/ml of FSH was most effective for [125I-Tyr13]ET-1 binding for 48-h culture, thereafter revealing a plateau. After 48 h of culture with 200 ng/ml of FSH, granulosa cells were further incubated with [125I-Tyr13]ET-1 (10 pM-1 nM) and/or [125I]IRL1620, the selective ETB receptor agonist (10 pM-1 nM) for 2 h for equilibrium study, and then the dissociation constant and the maximal binding capacity between receptors and ligands were determined by saturation curve and Scatchard plot analysis. ETA + ETB, ETB, and ETA (sites/cells) showed a 4.4-, 2.6-, and 7.5-fold increase, respectively. As for steroidogenesis, ET-1 (100 nM) or ET-3 (100 nM) suppressed FSH-induced progesterone and 17 beta-estradiol production. These results indicate that FSH upregulates both ETA and ETB receptors in DES-treated immature rat granulosa cells, with no significant differences between ET-1 and ET-3, and that ET-1 or ET-3 suppresses FSH-induced steroidogenesis. ETs may affect the granulosa cell function through the ETA and ETB receptors, and the increase in amount of ET binding does not reflect ET effects on granulosa cell function. The ET receptor plays an important role in the development of the ovary.

Animals↗

Changes with age and sex in levels of plasma and ovarian or testicular endothelin-1 in rats.

Mammalian ovaries and testes contain various intragonadal peptides necessary to control gonadal function. Effects of aging and sex on total plasma and ovarian or testicular endothelin-1 (ET-1) levels were studied in female and male rats aged 4-140 days. At 2 weeks, plasma ET-1 levels were 2.69 +/- 0.09 and 2.41 +/- 0.03 pg/ml (mean +/- SEM; n = 10) in the female and male, respectively. After a temporary decrease, mean ET-1 concentrations increased at 10 weeks and again decreased at 20 weeks in the female, thereafter revealing a plateau, whereas the ET-1 concentrations gradually decreased in the male. In adult females, plasma ET-1 levels were 3.7-fold higher than male levels. Ovarian ET-1 levels gradually increased after birth to 2 weeks, then decreased, and again increased at 3 weeks. Thereafter they gradually decreased, showing a plateau after 10 weeks. In contrast, testicular ET-1 levels gradually decreased after birth. This difference is parallel to but much larger than the sex difference in ovarian or testicular ET-1. Gonadal ET-1 showed a very different ontogeny.

Adsorption↗

A case of mid-trimester intrauterine fetal death with Cushing's syndrome.

A 34-year-old woman was diagnosed with Cushing's syndrome after her first pregnancy ended in intrauterine fetal death at 25 weeks' gestation. She subsequently had a successful pregnancy after treatment of her disease. Although patients with Cushing's syndrome rarely conceive, abortion, preterm labor, and intrauterine growth retardation are common when they do.

Adrenal Cortex Neoplasms↗

Hydrostatic pressure induces expression of interleukin 6 and tumour necrosis factor alpha mRNAs in a chondrocyte-like cell line.

OBJECTIVES: To clarify the effect of pressure on the expressions of proteoglycan core protein and metabolism related cytokines in a chondrocyte-like cell line, HCS-2/8. METHODS: HCS-2/8 cells were exposed to 1, 5, 10, or 50 MPa of hydrostatic pressure (HP) for two hours, and mRNA expressions of interleukin 6 (IL6) and tumour necrosis factor alpha (TNFalpha) were examined by using reverse transcription-polymerase chain reaction (RT-PCR) method with specific primer sets; and mRNA of proteoglycan core protein, stromelysin, and tissue inhibitor of metalloproteinase 1 (TIMP1) were measured with northern blotting. RESULTS: HP exposure caused temporal morphological changes of the cells, but did not affect cellular viability, IL6 and TNFalpha mRNA expressions were not observed in the control cells under the atmospheric pressure, whereas in the cells treated with HP, pressure dependent enhancement of IL6 mRNA expression was observed between 30 minutes and four hours after HP release. TNFalpha mRNA expression also increased 30 minutes after the exposure to 50 MPa of HP and disappeared four hours later. Proteoglycan core protein mRNA levels increased between 30 minutes and four hours after the exposure to 1 or 5 MPa of HP, whereas the levels decreased after 10 or 50 MPa of HP. Stromelysin and TIMP1 mRNA signals did not respond to HP. CONCLUSION: HP at excessively high levels induced IL6 and TNFalpha expression and reduced the expression of proteoglycan core protein, while physiological levels of HP increased the expression of proteoglycan core protein. These findings are important when considering the pathology of osteoarthritis.

Aggrecans↗

Continuous administration of basic fibroblast growth factor (FGF-2) accelerates bone induction on rat calvaria--an application of a new drug delivery system.

Some studies have shown that locally applied basic fibroblast growth factor (FGF-2) enhances bone regeneration at a fracture site, while others have not been in agreement. We developed a new continuous FGF-2 delivery system designed to accelerate cytokine-induced new bone formation. A subperiosteal pocket was surgically formed in 36 eight-week-old male Wistar rats. The rats were administered 0, 1, 10, or 100 ng of FGF-2 contained in a collagen minipellet, mixed with allogeneic demineralized bone matrix in a dome-shaped Millipore filter and then placed into the pocket. New bone formation in the dome was evaluated at 2, 4, and 8 wks after placement. Soft x-ray radiographs disclosed an apparently larger radiopaque region in the 1-ng group at 4 wks compared with those in the other groups. Morphometrical analysis revealed that the new bone area in the 1-g group was significantly larger than that in the 0-g group (p<0.01). In the 100-ng FGF-2 group, new bone formation seemed suppressed. We concluded that continuous slow administration of a small amount of FGF-2 accelerates bone-derived osteogenic cytokine-induced new bone formation.

Animals↗

Effects of genistein and staurosporine on angiotensin II-induced DNA synthesis, protein synthesis and mitogen-activated protein kinase activation in vascular smooth muscle cells.

This study examines the effects of protein kinase inhibitors and activator on angiotensin II-induced DNA synthesis and protein synthesis of rat aortic smooth muscle cells. In quiescent confluent cells, angiotensin II induced a concentration-dependent increase in thymidine incorporation and leucine incorporation. The tyrosine kinase inhibitor genistein caused an inhibition of the angiotensin II-induced DNA synthesis but not of the agent-induced protein synthesis. The protein kinase C inhibitors staurosporine and calphostin C caused an inhibition of the angiotensin II-induced protein synthesis but not of the agent-induced DNA synthesis. The protein kinase C activator phorbol 12-myristate 13-acetate stimulated protein synthesis. Angiotensin II stimulated mitogen-activated protein (MAP) kinases and the angiotensin II-induced MAP kinase activation was inhibited by genistein but not by staurosporine. These findings suggest that angiotensin II-induced DNA synthesis is at least partly mediated via protein-tyrosine phosphorylation and angiotensin II-induced protein synthesis is at least partly mediated by activation of protein kinase C. It seems likely that MAP kinase activation is involved in DNA synthesis but not in protein synthesis induced by angiotensin II.

Angiotensin II↗

[Amyloidogenic peptides such as beta-amyloid, amylin and calcitonin strongly enhance the susceptibility of rat hippocampal neurons to excitatory amino acids in vivo].

We have previously shown that in vivo injection of beta-amyloid (beta 1-40, beta 25-35) with non-toxic amounts of ibotenic acid, an excitatory amino acid, causes synergistic and drastic neuronal degeneration in rat hippocampus. It was, however, yet not clear whether the neuronal degeneration in vivo was associated with their primary amino acid sequences, their secondary beta-structure or their activities to suppress MTT reduction activity in vitro. In addition to beta-amyloid, other amyloidogenic peptides such as human amylin or calcitonin are known to deposit extracellularly in systemic and peripheral amyloidosis. In this study, we measured the activity of amyloidogenic peptides (beta 1-40, human amylin and calcitonin) to suppress cellular MTT reduction activity in vitro and their synergistic neurodegeneration with ibotenic acid in vivo. All amyloidogenic peptides, but not non-amyloidogenic peptides (beta 40-1, BSA), suppressed the MTT reduction activity in HeLa cells and in the primary cultured neurons in vitro, and also produced the synergistic neuronal cell loss in rat hippocampal region by enhancing the toxicity of ibotenic acid in vivo. The deposits of amyloidogenic peptides at the injection sites were thioflavin S fluorescence positive, suggesting the fibrillary beta-structures. These results indicate that the neurodegeneration in vivo by amyloidogenic peptides is strongly associated with their fibrillary beta-structure and their activity to suppress MTT reduction activity in vitro.

Amyloid↗

Decrease of the obese gene expression in bovine subcutaneous adipose tissue by fasting.

The expression of mRNA of leptin, the product of the obese gene, in bovine adipose tissue was analyzed by a lysate RNase protection assay. The mRNA level was significantly decreased by food deprivation for two days and partially recovered after 3 hr of refeeding, indicating that obese gene expression in the ruminant was regulated by feeding.

Adipose Tissue↗