Search PubMed⌕ Search

Biomedical subjects

T Kajimoto

Publications and source records attributed to T Kajimoto.

34 records · Page 2Linked to original sources
PubMed1997

A search for pyrophosphate mimics for the development of substrates and inhibitors of glycosyltransferases.

The design and synthesis of several beta-1,4-galactosyltransferase inhibitors are reported. Mimics of the pyrophosphate-Mn2+ complex were the focus of the design. Malonic, tartaric, and monosaccharide moieties were used as replacements of the pyrophosphate moiety, and galactose or azasugars with potent galactosidase inhibitory activity were used as the 'donor' component. Compound 6, in which glucose was used as the pyrophosphate-Mn2+ complex mimic and galactose as the 'donor' component, showed the best inhibitory activity towards the transferase with a Ki of 119.6 microM.

Aminoglycosides↗
PubMed1996

Formation of apatite-collagen complexes.

An apatite-collagen complex was prepared in calcium beta-glycerophosphate solutions at pH 9.0 and 37 degrees C with the purpose of developing new bone substitutes that more closely resemble bone than currently available materials. Reconstituted type I collagen as well as sheet collagen were crosslinked in the presence of alkaline phosphatase and egg-yolk phosvitin. The crosslinked collagens were immersed in daily-renewed calcium beta-glycerophosphate solutions for 2 and 4 weeks to induce the deposition of apatite on the collagen fibers. After 2 weeks of reaction, for example, apatites deposited approximately two times the crosslinked collagen in weight. With reconstituted collagen, the complex showed some elasticity but no apatite was visually observed to detach under deformation with fingers and forceps. The complex, moreover, did not disintegrate when immersed in saline or animal blood. Nevertheless, the complex resorbed with no evidence of cytotoxicity when implanted in muscle tissues. These findings suggest that the apatite-collagen complex prepared would be useful as bone substitutes, especially for periodontal osseous lesion repair and alveolar ridge augmentation.

Alkaline Phosphatase↗
PubMed1996

Design and synthesis of C-linked fucosides as inhibitors of E-selectin.

Two series of C-linked fucosides as mimetics for the tetrasaccharide sialyl Lewis X have been synthesized and tested as inhibitors of E-Selectin. The fucopeptides have been prepared from three key intermediates, including alpha-C-allyl fucose, natural and unnatural amino acids bearing hydroxyl groups and an alpha, omega-diacid moiety for the imitation of the essential three parts of SLex, i.e., the Fuc, Gal, and NeuAc. The nature and distance of the linkage of the fucose moiety to the amino acids as well as the distance between the amino acids and the terminal carboxylic acid group turned out to be crucial for the biological activity. In addition the necessity of both OH groups (4- and 6-OH) in the Gal part could be confirmed. Conformational NMR study of the most active mimetic supports the structure-activity relationship. A second series of mimetics was prepared, where Fuc and Gal moieties were purely C-linked. In the synthesis of beta-C-allyl galactose an intramolecular 1,2-hydride shift led to an interesting side product. However, the substituted glycosidic oxygens led to a substantial loss of conformational constrain, which could not be compensated and resulted in low activity.

E-Selectin↗
PubMed1995

Hepatocellular carcinoma complicating biliary cirrhosis caused by biliary atresia: report of a case.

A case of hepatocellular carcinoma complicating biliary cirrhosis caused by biliary atresia is reported. The patient had persistent severe jaundice with hepatosplenomegaly. A liver tumor was suspected because of the elevated serum alpha-fetoprotein and was shown by ultrasonography at 6 years of age. The tumor was treated with percutaneous ethanol injection therapy (PEIT). Nine months after initiation of PEIT, the patient died of massive bleeding from a metastatic tumor.

Biliary Atresia↗
PubMed1995

[Relation between electrogastrography and gastric electromyogram, mechanical activity].

Electrogastrography (EGG) appears to be useful method to evaluate the gastric motility as noninvasive approach. However, it is not known what EGG means. The aim of this study is to make clear the meanings of electrical activity recorded dy EGG for gastric motility. EGG recorded by cutaneous electrodes was compared to gastric electromyogram recorded by serosal electrodes and gastric mechanical activity recorded by straingauge transducer in anesthetized and conscious dogs. EGG recordings were preserved when gastric mechanical activity was not recognized. In digestive state, amplitude of EGG, electromyogram and mechanical activity increased significantly (p < 0.01). Significant correlation between amplitude of EGG and amplitude of electromyogram and mechanical activity of antrum were seen (p < 0.01). In interdigestive state, amplitude of EGG in phase 3 increased significantly (p < 0.05) compared to that in phase 1. Significant correlation between amplitude of EGG and amplitude of electromyogram and mechanical activity were seen in phase 2 (p < 0.01). EGG reflected electrical control activity (ECA) and electrical response activity (ERA). EGG recordings showed electromyogram and mechanical activity of gastric antrum. Amplitude of EGG reflected electromyogram and mechanical activity in phase 2 in interdigestive state. EGG waves did not always agree on myoelectrical waves.

Animals↗
PubMed1993

Shoot dynamics of Pinus pumila in relation to altitudinal and wind exposure gradients on the Kiso mountain range, central Japan.

Seasonal shoot dynamics of Japanese mountain stone pine (Pinus pumila Regel.) growing at six sites with different altitudes and slope aspects on the Kiso mountain range in central Japan were investigated. The shoots followed a similar growth pattern at all sites; current shoots elongated rapidly during June and July, and the current needles grew during July and August. Final lengths of the current shoots and needles decreased with increasing altitude. Current-shoot lengths were also shorter at the windward sites than at the leeward sites. At all sites, leaf senescence occurred intensively between mid-August and mid-September. Needle longevity, i.e., the age of the oldest living needle attached to a shoot, increased with increasing altitude. Fascicle density, i.e., the number of current needle fascicles on a unit shoot length, was greater at higher altitudes and windward sites than at lower altitudes and leeward sites. Seasonal dynamics of the P. pumila shoots were characterized by simultaneous replacement of old needles with new needles in the early autumn, thus avoiding any loss of canopy photosynthetic production during the growing season. Increases in needle longevity and fascicle density were associated with declining air temperature and increasing wind exposure. Needle longevity and fascicle density were characteristics of adaptive plasticity in P. pumila that prevent a reduction in growth potential in the stressful conditions of alpine regions.

Journal Article↗
PubMed1990

The internal anal sphincter in anorectal malformation.

Recently it has been morphologically clarified that a layer of thick smooth muscle, mimicking the internal anal sphincter, exists at the rectal and even in high and intermediate anorectal malformations. This paper will describe two studies focussed on the internal anal sphincter in anorectal malformation. I. Experimental study: Utilisation of the rectal end for reconstructive surgery would necessitate the mobilisation of the rectum. We performed a chronic animal experiment in order to investigate the influence of rectal mobilisation on anal function and the role of the internal anal sphincter in anal continence. Fifteen dogs were operated on; rectal separation was performed in 5 dogs, resection of the internal anal sphincter in 5 dogs and both procedures in 5 dogs. Anorectal manometric studies for 24 weeks revealed that rectal separation caused only a transient mild disturbance in anal functions with the exception of long-standing high rectal compliance, while resection of the internal anal sphincter caused a persistent severe disturbance. II. Clinical study: The function of the smooth muscle thickening at the rectal end was investigated and operations to preserve the rectal end were evaluated in cases of high and intermediate anorectal malformations. In 5 infants with anorectal malformations (high type 2, intermediate type 3), for whom colostomies had been performed as newborn, a preoperative manometric study at the rectal end was performed with a probe introduced from the distal colostomy. Thereafter, they all underwent a rectal end preserving operation. They were followed up manometrically and clinically after the operation. A preoperative manometric study of the rectal end showed the presence of rhythmic activity in all and positive reflexive pressure fall by rectal distension in 4. The rectal end preserving operation maintained rhythmic activity in all of them, rectoanal reflex in 3 and good results are expected clinically. These two studies suggest that the functional internal anal sphincter, which exists at the rectal end also in high and intermediate anorectal malformations, should be utilised for reconstruction because of the essential role it plays in anal continence.

Anal Canal↗
PubMed1989

[Basic study of the application of 2 piece-type hydroxyapatite anchor in periodontal therapy].

Clinico-histological studies were made to obtain basic data on the application of 2 piece-type hydroxyapatite (hereinafter referred to as HAP) originally designed and prepared so as to be shaped to make its clinical application easy as an anchor (HAP anchor) in the corrective movement of teeth. An immobility identification experiment and intrusive experiment were performed in order to identify absent loss of anchor to the corrective force and to identify actually practicable tooth movement by means of the HAP anchor, respectively, and clinico-histological evaluation was made of its function in both of the above cases. The results revealed no change in the distance of HAP anchor in the former experiment and tooth intrusion of 3.7 mm on average in the latter experiment and, histologically, close surrounding of almost the entire region embedded by the HAP anchor, with newly formed osseous tissues in both experiments. The above results suggest the usefulness of this trial HAP anchor as an anchor to tooth movement in periodontal therapy.

Bone Regeneration↗
PubMed1989

[Clinical evaluation of synthetic hydroxyapatite implants for human periodontal osseous defects. 6 cases studied more than 3 years after the surgery].

We applied of granular hydroxyapatite HAP to periodontal bone defects, for the purpose of restoring the periodontal tissue destroyed by periodontal disease, the subjects were 6 patients (6 regions) with chronic marginal periodontitis who had passed more than 3 years since HAP implantation. After routine periodontal initial treatment, a flap operation was performed, and granular HAP, or a combination of granular and block-like HAP, was implanted into the periodontal bone defect. Clinical parameters were probing depth, clinical attachment level, clinical gingival margin, residual HAP volume and X-ray before operation, at 3, 6, 12 months, and 2, 3, and 4, 6 years after the operation. The results revealed that all measured values showed good results for both granular HAP and the combination of granular and block-like HAP after implantation, and that all cases showed stable results from 12 months on. No remarkable difference was noted between the implanted regions.

Bone Resorption↗
PubMed1986

Steroidogenic effect of ent-kaur-16-en-15 beta-ol (kaurenol) on isolated rat adrenal cells.

In an in vitro bioassay system for adrenocorticotropic hormone using isolated rat adrenal cells, kaurenol, a diterpene alcohol, stimulated corticosterone production and augmented the steroidogenic effect of adrenocorticotropin or forskolin, dose-dependently. Kaurenol had no effect on cyclic AMP production by the cells. The diterpene also had no stimulatory effect on the adrenal adenylate cyclase activity in a cell free system. The results suggest that this particular diterpene exerts a steroidogenic effect through a mechanism independent of cyclic AMP generation.

Adenylyl Cyclases↗
PubMed1976

Modifying effects of inactivated bovine serum on the acute toxicity of methylmercuric chloride in cells cultured in vitro.

Dynamics of the killing of Ehrlich's murine ascites tumor cells by methylmercuric chloride, MMC, were investigated. Thresholds in the killing action of MMC were observed in the MMC treatment concentration, but not in the MMC treatment time. Inactivated bovine serum protected the E-cells from killing by MMC in vitro. The apparent MMC toxicity was reduced as the serum concentration increased, but remaining partially at high concentrations. Thus the serum increases the threshold for MMC toxicity. It was confirmed that the mode of action, observed as the kinetics of the acute lethality by suspicious substances, could be examined promptly on the mammalian cell level by the present experimental system.

Animals↗