PubMed Health⌕ Search

Biomedical subjects

H Kajiwara

Publications and source records attributed to H Kajiwara.

At least 19 recordsLinked to original sources
PubMed2001

Bilirubin calculi crushing by laser irradiation at a molecular oscillating region wavelength based on infrared absorption spectrum analysis using a free-electron laser: an experimental study.

We investigated a new laser technique of crushing bilirubin calculi, our aim being to crush calculi in isolation using a minimally invasive procedure. Infrared absorption spectrum analysis of the bilirubin calculi was conducted, revealing maximum absorption spectrum at a wavelength of the C=O stretching vibration of ester binding that exists within the molecular structure of bilirubin calcium. As an experiment to crush calculi using the free-electron laser, we set the laser at the effective irradiation wavelength of ester binding, and conducted noncontact irradiation of the bilirubin calculi. The calculi began to slowly ablate until the irradiated site had been completely obliterated after 20s of irradiation. Moreover, absorption spectrum analysis of the irradiated site, from a comparison of absorption peak ratios, revealed that absorption peak intensities decreased over time at the absorption wavelength of ester binding. These findings suggest that irradiation of molecular oscillating region wavelengths peculiar to calculi based on infrared absorption spectrum analysis results in the gradual crushing of calculi in isolation by breaking down their molecular structure.

Bilirubin↗
PubMed2000

Effect of troponin I phosphorylation by protein kinase A on length-dependence of tension activation in skinned cardiac muscle fibers.

We examined the effect of troponin I (TnI) phosphorylation by cAMP-dependent protein kinase (PKA) on the length-dependent tension activation in skinned rat cardiac trabeculae. Increasing sarcomere length shifted the pCa (-log[Ca2+])-tension relation to the left. Treatment with PKA decreased the Ca2+ sensitivity of the myofilament and also decreased the length-dependent shift of the pCa-tension relation. Replacement of endogenous TnI with phosphorylated TnI directly demonstrated that TnI phosphorylation is responsible for the decreased length-dependence. When MgATP concentration was lowered in the absence of Ca2+, tension was elicited through rigorous cross-bridge-induced thin filament activation. Increasing sarcomere length shifted the pMgATP (-log[MgATP])-tension relation to the right, and either TnI phosphorylation or partial extraction of troponin C (TnC) abolished this length-dependent shift. We conclude that TnI phosphorylation by PKA attenuates the length-dependence of tension activation in cardiac muscle by decreasing the cross-bridge-dependent thin filament activation through a reduction of the interaction between TnI and TnC.

Adenosine Triphosphate↗
PubMed2000

Effects of MgADP on length dependence of tension generation in skinned rat cardiac muscle.

The effect of MgADP on the sarcomere length (SL) dependence of tension generation was investigated using skinned rat ventricular trabeculae. Increasing SL from 1.9 to 2.3 microm decreased the muscle width by approximately 11% and shifted the midpoint of the pCa-tension relationship (pCa(50)) leftward by about 0.2 pCa units. MgADP (0.1, 1, and 5 mmol/L) augmented maximal and submaximal Ca(2+)-activated tension and concomitantly diminished the SL-dependent shift of pCa(50) in a concentration-dependent manner. In contrast, pimobendan, a Ca(2+) sensitizer, which promotes Ca(2+) binding to troponin C (TnC), exhibited no effect on the SL-dependent shift of pCa(50), suggesting that TnC does not participate in the modulation of SL-dependent tension generation by MgADP. At a SL of 1. 9 microm, osmotic compression, produced by 5% wt/vol dextran (molecular weight approximately 464 000), reduced the muscle width by approximately 13% and shifted pCa(50) leftward to a similar degree as that observed when increasing SL to 2.3 microm. This favors the idea that a decrease in the interfilament lattice spacing is the primary mechanism for SL-dependent tension generation. MgADP (5 mmol/L) markedly attenuated the dextran-induced shift of pCa(50), and the degree of attenuation was similar to that observed in a study of varying SL. The actomyosin-ADP complex (AM.ADP) induced by exogenous MgADP has been reported to cooperatively promote myosin attachment to the thin filament. We hereby conclude that the increase in the number of force-generating crossbridges on a decrease in the lattice spacing is masked by the cooperative effect of AM.ADP, resulting in depressed SL-dependent tension generation.

Adenosine Diphosphate↗
PubMed2000

Contribution of sodium channel and sodium/hydrogen exchanger to sodium accumulation in the ischemic myocardium.

Contribution of sodium channels and sodium/hydrogen exchangers (NHEs) to sodium accumulation during ischemia in the ischemic/reperfused heart was examined. Ischemia increased the myocardial sodium. Reperfusion elicited a further increase in the myocardial sodium, which was associated with little recovery of the left ventricular developed pressure (LVDP) of the perfused heart. Treatment with tetrodotoxin or dimethylamirolide (DMA) dose-dependently attenuated the ischemia- and reperfusion-induced increase in myocardial sodium and enhanced the post-ischemic recovery of the LVDP. There was an inverse relationship between the increase in myocardial sodium during ischemia and the post-ischemic recovery of the LVDP.The myocardial sodium accumulation during ischemia is mainly attributed to sodium influx through sodium channels and NHEs.

Amiloride↗
PubMed2000

Immunohistochemical study of type-1 blood antigen expressions in thyroid tumors: the significance for papillary carcinomas.

Immunohistochemical expressions of type 1 blood group antigens were studied for 95 cases of thyroid tumors, including 29 follicular adenomas, 23 follicular carcinomas, and 43 papillary carcinomas, applying monoclonal antibodies against DU-PAN-2, CA19-9, Lewis(a) (Le(a)), and Lewis(b) (Le(b)). Normal thyroid tissue invariably failed to express all four antigens. In follicular adenomas, DU-PAN-2 and CA19-9 were focally expressed in 7% and 21% of cases, and in follicular carcinomas, CA19-9 expression was limited to one case (4%); all cases were negative for DU-PAN-2. No or little expression of Le(a) or Le(b) was observed in these follicular tumors. In contrast, DU-PAN-2, CA19-9, Le(a), and Le(b) were expressed in 98%, 84%, 33%, and 49% of 43 papillary carcinomas, respectively. The positive stainings were observed mainly on the luminal surface of the tumor cells. The number of tumor cells that expressed DU-PAN-2 generally was greater than that of tumor cells that expressed CA19-9, Le(a), or Le(b). There was no significant difference in antigen expressions in female papillary carcinomas between subjects who were younger and older than 50 years old. The results suggest that DU-PAN-2 would be a useful immunohistochemical marker for distinguishing papillary carcinomas from follicular tumors. These immunohistochemical profiles imply the following: the activity of alpha2-3 sialyltransferase, a specific glycosyltransferase, would be more strongly enhanced in papillary carcinomas than in follicular tumors; the antigen expressions in papillary carcinomas may not be related to the alteration of the female sex hormone environment.

Adenocarcinoma, Follicular↗
PubMed2000

The effects of a novel cyclohexane dicarboximide derivative, ST-6, on hypoxia/reoxygenation injury in perfused rat heart.

The present study was undertaken to test if some cyclohexane dicarboximide derivatives may have a cardioprotective effect against hypoxia/reoxygenation injury. Isolated rat hearts were subjected to 20-min of hypoxia followed by 45-min reoxygenation, and their recovery of post-hypoxic cardiac contractile function was examined. Treatment with agents was carried out from 3 min after the onset of hypoxia to the end of hypoxia (17 min during hypoxia). Among the 17 compounds, 2-[4-[4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl]butyl]hexahydro-1H-i soindol-1,3(2H)-dione (ST-6) showed a significant enhancement of post-hypoxic contractile force. This was associated with attenuation of the releases of creatine kinase and purine nucleosides and bases from the perfused heart. Hypoxia-induced increase in myocardial sodium and decrease in potassium ion content was suppressed by ST-6 treatment. The results suggest that ST-6 is capable of protecting the heart against hypoxia/reoxygenation injury possibly through a mechanism by which sodium overload during hypoxia is suppressed.

Animals↗
PubMed2000

[Photodynamic diagnosis and photodynamic therapy for experimental hepatoma with ME 2906].

We studied the effects of photodynamic diagnosis (PDD) and photodynamic therapy (PDT) in confirming the existence of hepatoma, using the new photosensitizer mono-L-aspartyl chlorine 6. Japanese white rabbits were selected for abdominal incision under intravenous anesthesia, and VX 2 tumor cells were transplanted into the left liver lobe to create a hepatoma model. In the experiment, hepatoma of 1 cm in diameter (at one week after transplantation) was radiated with a semiconducter laser (664 nm, 200 J/cm2) for treatment.

Animals↗
PubMed1999

Relationship between myocardial cation content and injury in reperfused rat hearts treated with cation channel blockers.

A role for K+ and Ca2+ channel blockers in cardiac contractile dysfunction and myocardial ionic imbalance was examined in isolated rat hearts with 35-min ischemia and 60-min reperfusion. The K+ channel blockers glibenclamide (1-30 microM) and sematilide (1-30 microM), Ca2+ channel blockers diltiazem (0.1-3 microM) and nicardipine (0.03-1 microM) and fast Na+ channel blocker tetrodotoxin (0.01-0.3 microM) were delivered for the last 3-min pre-ischemia. Ischemia-induced increase in Na+ content was attenuated by diltiazem and tetrodotoxin at all concentrations employed and by nicardipine at 0.3 microM, whereas the ischemia-induced loss of K+ was suppressed partially by glibenclamide and sematilide and almost completely by the two drugs in combination. Left ventricular developed pressure of untreated hearts did not recover upon reperfusion, which was associated with increases in myocardial Na+ and Ca2+ contents and decreases in K+ and Mg2+ contents. Glibenclamide and sematilide neither enhanced the post-ischemic recovery of left ventricular developed pressure nor affected cation changes during reperfusion. Diltiazem enhanced the recovery of left ventricular developed pressure and attenuated imbalance of the myocardial Na+ during ischemia and of all myocardial cations examined during reperfusion. The effects of nicardipine on these parameters were small. Tetrodotoxin enhanced the recovery of left ventricular developed pressure and reversed the imbalance of all myocardial cations examined during reperfusion in a concentration-dependent manner. The results suggest that blockade of transmembrane flux of K+ during ischemia plays a minor role in the improvement of post-ischemic contractile recovery, rather blockade of transmembrane flux of Na+ attenuates the ischemia and reperfusion injury.

Animals↗
PubMed1999

New methods of control against postoperative methicillin-resistant Staphylococcus aureus infection.

The incidence of postoperative infections caused by methicillin-resistant Staphylococcus aureus (MRSA) in Japan has been increasing dramatically. In March 1990, we assigned special doctors in infection control (infection control doctor, ICD), and defined comprehensive controls against MRSA infection. A total of 3536 cases of digestive tract surgery performed at our department were studied during the period between September 1987 and August 1997. We changed the use of antibiotics to prevent postoperative infection. Cefazolin (CEZ) was employed for surgery of the upper digestive tract, including esophagus, stomach, duodenum, and gallbladder. Cefotiam (CTM) was employed for surgery of the lower digestive tract, liver, and pancreas. In esophageal resection, the tracheal tube was extracted during the early postoperative period, and for cervical esophagogastroanastomosis, the autosuture was changed to layer-to-layer anastomosis. We have achieved successful control of postoperative MRSA infection, the incidence having decreased to 0.3% (9/2703). In conclusion, our methods of control against postoperative MRSA infection implies that comprehensive measures of prevention, including the reviewed specification and usage of antibiotics and operation management, have been well implemented. This value is the lowest and the first of any domestic hospital or institute in Japan, suggesting a continued and significant decrease.

Cephalosporins↗
PubMed1999

Photodynamic therapy using mono-L-aspartyl chlorin e6 for rabbit experimental hepatoma.

Photodynamic therapy and photodynamic diagnosis using photosensitizers have yet to be clinically employed for hepatoma. Mono-L-aspartyl chlorin e6, a chlorin derivative with high tumor affinity developed as a second-generation photosensitizer, enables rapid tumor detection after administration, without light-shielding. This study examined the potential of photodynamic therapy, using this photosensitizer, for hepatoma in rabbits. VX2 tumor cells were transplanted into the liver of Japanese white rabbits, and the animals were administered 2.5 mg/kg of mono-L-aspartyl chlorin 36 1 week later. Accumulation of mono-L-aspartyl chlorin e6 in hepatoma was observed over time with an epifluorescence stereoscope, and the efficacy of continuous photodynamic therapy following photodynamic diagnosis was examined. A diode laser system was used for treatment, and efficacy was examined in a control group and four other groups that were irradiated at different times following administration. Efficacy in suppressing tumor growth, tumor necrosis rates, and efficacy in suppressing pulmonary metastasis were studied. For all these aspects, treatment was significantly more effective in the group irradiated 5 minutes after administration than in groups irradiated at later times. Liver function testing in all groups revealed no distinct disorders. Photodynamic therapy with mono-L-aspartyl chlorin e6 may be suitable for clinical use in therapy for hepatoma.

Analysis of Variance↗
PubMed1999

Late vasospasm of the inferior epigastric artery graft.

We report a case of vasospasm of a free inferior epigastric artery graft at 5-year angiographic follow-up after coronary artery bypass grafting. Although the cause of spasm was not clear, the graft was viable and had a vasoconstrictor profile similar to a gastroepiploic artery graft at long-term follow-up.

Coronary Angiography↗
PubMed1999

Pit-1 positive alpha-subunit positive nonfunctioning human pituitary adenomas: a dedifferentiated GH cell lineage?

Pit-1 is a transcription factor which has been reported to regulate differentiation toward GH, PRL and TSH in the anterior pituitary glands. In the human pituitary adenomas, Pit-1 is highly expressed in GH secreting and TSH secreting adenomas as it can well be anticipated. Interestingly, human non-functioning pituitary adenomas also express Pit-1, especially it was expressed in all alpha SU positive nonfunctioning adenomas. The human anterior pituitary cells are special in comparison with rodents in a finding that alpha SU is frequently colocalized with GH. As alpha SU is the first hormone appearing during fetal development in the rodent pituitary glands, it may be postulated that alpha SU Pit-1 positive cells undergo differentiation in the GH cell lineage. From this background, this paper proposes that "alpha SU positive Pit-1 Positive" cells are the ones in the GH cell lineage, more specifically a dedifferentiated cell lineage toward alpha SU/GH/Pit-1.

Adenoma↗
PubMed1999

Degenerative processes of elastic fibers in sun-protected and sun-exposed skin: immunoelectron microscopic observation of elastin, fibrillin-1, amyloid P component, lysozyme and alpha1-antitrypsin.

Degenerative processes of elastic fibers in sun-protected and sun-exposed skin were analyzed by light and electron microscopic (post-embedding) immunocytochemistry using antisera to elastin, fibrillin-1, amyloid P component, lysozyme and alpha1-antitrypsin. To assess the effect of aging and sun exposure, biopsy specimens of sun-protected skin (back) and severely and moderately sun-exposed skin (face and forearms) were obtained from a young age group (1-27 years), an adult group (31-56 years) and an old aged group (61-100 years). Elastin and fibrillin-1 were the essential components of elastic fibers; elastin being localized in the electron-lucent matrix and fibrillin-1 in the dense microfibrillar strands. Aging and sun exposure provoked degenerative condensed spots, which represented widened dense microfibrillar strands, in the matrix of altered elastic fibers in the reticular dermis. Amyloid P component was first deposited on the peripheral microfibrils, and then in the intermediate density zone of the spots. Lysozyme was observed in both the electron-dense core and in the intermediate density zone of the spots. Deposition of lysozyme correlated with basophilic degeneration of the elastic fibers. In the severely photodamaged facial skin of the aged, which showed solar elastosis in the upper reticular dermis, fibrillin-1 immunoreactivity was lost from the thickened and vacuolated elastic fibers that lacked condensed spots, and amyloid P component, lysozyme and alpha1-antitrypsin were diffusely deposited in the elastin-positive matrix. It seemed that amyloid P component deposition on the elastic fibers was closely associated with aging, while immunoreactive lysozyme was related to sun exposure. Vertically oriented, thin, elastic (oxytalan) fibers in the papillary dermis tended to decrease with age, with frequent deposition of amyloid P component but no lysozyme. In the facial skin of the aged, dermal papillae disappeared, with the formation of degenerative elastic globules beneath the dermal-epidermal junction. The present study demonstrated an intimate relationship between ultrastructural alterations and deposition of exogenous substances on the degenerative elastic fibers in sun-exposed and/or aged skin.

Adolescent↗
PubMed1999

Modulation of Ca2+ transient decay by tension and Ca2+ removal in hyperthyroid myocardium.

We investigated the contribution of sarcoplasmic reticulum (SR) and Na+/Ca2+ exchanger in the tension-dependent change in the decay of the Ca2+ transients (CaT) in euthyroid (Eu) and hyperthyroid (Hy) myocardium. Hy was induced by thyroxine treatment to enhance the rate of SR Ca2+ uptake. With the use of the aequorin method, CaT and tension in twitch contraction were simultaneously measured under various conditions (changing muscle length and Ca2+ concentration in solution). In both groups, the decay time of CaT (DT) showed a significant dependence on the developed tension, but the tension dependence of DT in Hy was significantly less than in Eu. In the presence of caffeine (3 mM), the tension dependence of DT in Hy became apparent as in Eu. Inhibition of Na+/Ca2+ exchanger by replacing Na+ with Li+ did not affect the dependence in Hy. The normalized extra Ca2+, which is the Ca2+ concentration change in response to a quick length change, in Hy was similar to that in Eu. pCa-tension relations of skinned trabeculae measured at different lengths (1.9 and 2.3 micrometer) were nearly identical in both groups. These results indicate that the tension-dependent change in the affinity of troponin C for Ca2+ works in both Eu and Hy myocardium and that the tension-dependent change in DT is influenced by the Ca2+ uptake rate of SR.

Animals↗
PubMed1999

Alterations in contractile properties and Ca2+ handling in streptozotocin-induced diabetic rat myocardium.

The mechanisms of the slower time courses of Ca2+ transients (CaT) and contraction in diabetic (diabetes mellitus, DM) myocardium were studied. The aequorin method was applied to papillary muscles of streptozotocin-induced DM and control rats. The time courses of CaT and tension of twitch in DM were slower than those in control, although the magnitudes of the CaT and contraction were identical. The dependence of CaT decay time and relaxation time on developed tension in DM and control rats differed. The length-tension relation in twitch and the pCa-tension relation in tetanus were identical in the two groups. The magnitude of extra Ca2+ (transient increase in intracellular Ca2+ concentration induced by a quick release in tetanus) was identical in both groups. pCa-tension relations of skinned trabeculae at different sarcomere lengths were nearly identical. The cross-bridge cycling rate (CCR) in DM was slower than that in control. These results indicate that the tension-dependent change in the Ca2+ affinity of troponin C in DM myocardium functions as in control myocardium. The slower time courses of CaT and tension in DM myocardium are caused by slower Ca2+ uptake by the sarcoplasmic reticulum and the slower CCR.

Animals↗
PubMed1999

Renal expression of insulin-like growth factor-l in acute renal failure: a preliminary report.

Renal expression of insulin-like growth factor-I (IGF-I) was examined in the specimens obtained at renal biopsy from five patients with acute renal failure (ARF) at the recovering phase. IGF-I peptide and mRNA were demonstrated in the cytoplasm of the epithelial cells of focal proximal tubules in four patients in whom renal function had been ameliorating. The stainings of IGF-I peptide and mRNA were intense in patients with favorable prognosis. Either IGF-I immunoreactivity or mRNA was not detected in the renal tissues in five cases with chronic renal insufficiency and four patients with renal carcinoma. Our preliminary findings suggest that IGF-I is locally produced in the kidney during the recovery period of ARF and might play roles in the repair processes, and extend the experimental observations in animal models into human pathophysiology.

Acute Kidney Injury↗
PubMed1999

Immunohistochemical expressions of prohormone convertase (PC)1/3 and PC2 in carcinoids of various organs.

In order to clarify the expression of prohormone convertase (PC) 1/3 and PC2 in various carcinoids and non-carcinoid endocrine tumors, we performed indirect immunoperoxidase staining on total of 19 cases of carcinoids (9 cases of bronchial carcinoids, 4 cases of rectal carcinoids, 4 cases of gastric carcinoids and 2 cases of bile duct carcinoids). Our study also included 7 non-carcinoid endocrine tumors. Seventy-nine% and 26% of carcinoids highly or strongly expressed positive staining for PC1/3 and PC2, respectively. High and strong expressions (3+ or 4+) of both PC1/3 and PC2 were noted in only bronchial carcinoids. Strong expressions for only PC1/3 were noted in rectal carcinoids. Bile duct carcinoids also demonstrated higher expressions of PC1/3 than those of PC2. These results suggested that high expressions of both PC1/3 and PC2 in bronchial carcinoids might reflect their diverse and frequent peptide production. The expressions of PC1/3 mRNA and PC2 mRNA detected by in situ hybridization in the bronchial carcinoids and rectal carcinoids were correlated with immunoexpressions of both of the antigens. The granular immunoexpression pattern of PC1/3 and PC2 visualized by confocal laser scanning microscopy would suggest the site of post-translational processing in the secretory granules. Non-carcinoid endocrine tumors showed low expressions (+ or 2+) of PC1/3 and PC2, except for thyroid medullary carcinoma showing high immunoexpression of PC1/3. Other non-carcinoid endocrine tumors (parathyroid adenomas and adrenal pheochromocytomas) revealed low immunoexpressions for both PC1/3 and PC2.

Adolescent↗