Biomedical subjects
Publications and source records attributed to M Takagi.
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We have carried out laboratory and clinical studies on rokitamycin (RKM, TMS-19-Q). The results are summarized as follows. Serum and urinary concentrations of RKM were determined in 6 children with ages between 6 and 12 years given single oral doses of 5, 10 and 15 mg/kg. Mean serum concentrations peaked at 30 minutes after administration of 5, 10 and 15 mg/kg, and respective peak values were 0.30 microgram/ml, 0.79 microgram/ml and 1.32 micrograms/ml. Biological half-lives for 5, 10 and 15 mg/kg were 2.0 hours, 1.65 hours and 1.36 hours. The 6-hour urinary recovery ranged from 1.11% to 2.58% after administration of 5 mg/kg, and the mean 6-hour urinary recoveries were 1.35% after administration of 10 mg/kg and 2.28% after administration of 15 mg/kg. Therapeutic responses were recorded as excellent or good in 22 (73.3%) of the children, comprising 6 with tonsillitis, 2 with pharyngitis, 4 with bronchitis, 1 with bronchopneumonia, 1 with Mycoplasma pneumonia, 2 with whooping cough, 5 with streptococcal infections, 5 with Campylobacter enteritis, 3 with impetigo and 1 with SSSS. The microbiological effectiveness of RKM on identified pathogens comprising 4 strains of Staphylococcus aureus, 1 strain of Streptococcus pneumoniae, 6 strains of Streptococcus pyogenes, 4 strains of Haemophilus influenzae and 5 strains of Campylobacter spp. was not so satisfactory as evidenced by a eradication rate of 50.0%. No significant side effect due to the drug was observed in any cases. In conclusion, RKM was found to be efficacious and safe for the treatment of bacterial infections in children.
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We have carried out laboratory and clinical studies on sultamicillin (SBTPC). The results are summarized as follows. SBTPC was given by oral administration to 2 children in a single dose at 5 mg/kg and to 3 children in a single dose at 10 mg/kg. After the oral administration, mean peak serum levels of ampicillin (ABPC) and sulbactam (SBT) obtained for the 2 dose levels were 1.91 +/- 1.34 and 2.06 +/- 1.06 micrograms/ml and 2.43 +/- 0.68 and 2.96 +/- 0.77 micrograms/ml at 1 hour, respectively, and mean half-lives were 0.80 +/- 0.10 and 0.98 +/- 0.46 hour and 1.57 +/- 0.57 and 2.01 +/- 0.70 hours, respectively. SBTPC was given to 2 children in a single dose at 15 mg/kg. After oral administration, the mean serum levels of ABPC and SBT at 30 minutes were 6.55 +/- 1.63 and 6.00 +/- 1.00 micrograms/ml, and the mean half-lives were 0.90 +/- 0.13 and 0.82 +/- 0.16 hour. SBTPC was given to 1 child at a single dose of 20 mg/kg. The peak serum levels of ABPC and SBT were 11.3 and 8.64 micrograms/ml, and the half-lives were 0.87 and 0.92 hour. Mean urinary excretion rates of ABPC and SBT were 38.4 +/- 2.7 and 34.6 +/- 4.7%, 43.0 +/- 3.6 and 41.6 +/- 5.8%, 47.7 +/- 5.2 and 51.6 +/- 3.5% in 6 hours and 66.1 and 59.2% in 8 hours after oral administration of 5 mg/kg, 10 mg/kg, 15 mg/kg and 20 mg/kg, respectively. Treatment with SBTPC was made in 34 cases of pediatric bacterial infections; 2 cases of pharyngitis, 19 cases of tonsillitis, 2 cases of bronchitis, 3 cases of impetigo, 2 cases of staphylococcal skalded skin syndrome, 4 cases of urinary tract infection and 1 case each of pneumonia and scarlet fever. Results obtained were excellent in 20 cases, good in 13 cases and poor in 1 case. No significant side effect due to the drug was observed in any cases.
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Pharmacokinetic and clinical studies on ceftriaxone (CTRX) in mature and premature neonates were carried out. The results are summarized as follows. The mean serum peak level of CTRX after intravenous administration at a single dose of 10 mg/kg in 4 to 13 day-old-neonates was 34.1 +/- 11.4 micrograms/ml at 30 minutes. The mean serum level at 12 hours after dosage was 11.1 +/- 2.1 micrograms/ml. The mean half-life time was 11.6 +/- 1.4 hours. Mean serum peak levels of CTRX after intravenous administration at a single dose of 20 mg/kg were 64.6 +/- 15.4 micrograms/ml in 1 to 3 day-old-neonates, 44.6 +/- 1.1 micrograms/ml in 5 day-old-neonates at 30 minutes. Mean serum levels at 12 hours after dosage in these two groups of neonates were 16.4 +/- 4.8 micrograms/ml and 12.4 +/- 2.5 micrograms/ml, respectively. Mean half-life times were 13.7 +/- 3.7 hours in 1 to 3 day-old-neonates and 10.2 +/- 1.3 hours in 5 day-old-neonates. CTRX was clinically effective in a case of urinary tract infection. No side effect was observed except an elevation of GOT.
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Platelet filamin was shown to cross-link F-actin and inhibit actomyosin ATPase activity. Filamin was also shown to be degraded by calpain (calcium-activated neutral proteinase; CANP) when the platelet was activated. The consequences of the proteolysis of filamin on the actomyosin system have been investigated. When degraded by calpain in the presence of Ca2+, filamin loses its ability to cross-link F-actin. Under the same conditions, its inhibitory effects on the superprecipitation and ATPase activity of actomyosin are abolished. The result suggests that the degradation of filamin is favorable for contraction of the activated platelets.
Caldesmon, a calmodulin and actin binding protein, has been shown to exist in platelet. In this report, it is shown that caldesmon specifically inhibits the effect of tropomyosin to enhance the actomyosin ATPase activity in platelet. Platelet tropomyosin enhances the MgATPase activity of platelet actomyosin. This effect is abolished by platelet caldesmon. In the absence of tropomyosin, however, caldesmon has no effect on the ATPase activity. The inhibition is not due to displacement of the binding of tropomyosin to F-actin by caldesmon. The result indicates that caldesmon is the specific inhibitor of tropomyosin in resting platelet.
Two cases of malignant rhabdoid tumor of the kidney (MRT) and two cases of bone metastasizing renal tumor (BMRT) were studied using electron microscopy and immunohistochemistry, in an attempt to evaluate the histogenetic relation to classical Wilms' tumor (2 cases). The two cases of MRT showed ultrastructural features of intermediate filament clusters in the cytoplasm. Vimentin, keratin, laminin, and peanut (PNA) lectin were immunohistochemically demonstrated in two cases of MRT. Tissue polypeptide antigen (TPA) was detected in one case. As for BMRT, the metastatic lesion exhibited numerous rosette-like structures of tumor cells. Vimentin was immunohistochemically demonstrated in one case, but no other antibodies were stained in two cases. Two cases of classical Wilms' tumor immunohistochemically demonstrated vimentin, keratin, PNA lectin, and TPA. MRT and BMRT fall within the broad spectrum of Wilms' tumors from the histogenetic aspect, but their clinical behavior is distinct.
The purpose of this study is to examine the changes in mechanical strength of two bioactive ceramics in living tissue. An aging test and dynamic fatigue test were performed using apatite-wollastonite-containing glass ceramics (A X W-GC) and dense hydroxyapatite (HA). Specimens (5 mm X 5 mm X 25 mm, abraded with No. 2000 Al2O3 powder) were implanted into subcutaneous tissue of rats for varying periods of time. The bending strength of aged samples was measured by the three-point loading method. The bending strength of A X W-GC was greater than that of HA (P less than 0.001). There was no reduction in bending strength for both A X W-GC and HA in living tissue. The n value of both A X W-GC and HA did not decrease significantly after implantation as assessed by the results of the dynamic fatigue test according to analysis of covariance. SEM-EPMA showed that Si and Mg contents decreased, Ca content did not change, while P content increased in the surface of A X W-GC. The area where x-ray intensity changed increased moderately after implantation. There were no changes in Ca and P at the interface between HA and soft tissue. In macroscopic and microscopic observations, specimens were found to be encapsulated with a thin layer of connective tissue. Foreign body giant cells, osteoblasts, or osteoclasts were not observed in the soft tissue. There was no bonding between ceramics and soft tissue.
The purpose of this study is to examine the chemical bonding mechanism between bioactive ceramics in vivo. Two experiments were performed. In the first experiment, rectangular specimens (5 mm X 5 mm X 25 mm) of apatite-wollastonite containing glass-ceramics (designated A.W-GC) were used. In the second experiment, plates (15 mm X 10 mm X 2 mm) of A.W-GC and three types of hydroxyapatite (designated HA) were used. The sintering temperature and porosity (%) of the three types of HA were 1200 degrees C (0.4%), 1000 degrees C (4.8%), and 800 degrees C (45%), respectively. In each experiment, two pairs of specimens of identical material, one bound with silk thread, the other not bound, were implanted subcutaneously into rats. In the first experiment, bonding of only bound specimens was observed at 3 and 6 months after implantation. The observation of interface by SEM-EPMA showed that a Ca-P-rich layer formed between the two specimens. In the second experiment, bonding of both bound and nonbound A.W-GC produced identical results 1 month after implantation. For HA sintered at 800 degrees C and 1000 degrees C, bonding was observed in every specimen. This phenomenon might be caused by the chemical change of hydroxyapatite occurring at different sintering temperatures. The Ca-P-rich layer was observed between two plates. These results suggest that self-repair of bioactive ceramic is possible under certain conditions.
The progressive changes of a Ca-P-rich layer between bone and three types of apatite-containing glass-ceramics of the same chemical composition: MgO 4.6, CaO 44.9, SiO2 34.2, P2O5 16.3, CaF2 0.5 (in weight ratio) were examined. Plates (15 mm X 10 mm X 2 mm, mirror surface) containing apatite (35 wt%) (designated A-GC), apatite (35 wt%) and wollastonite (40 wt%) (designated A.W-GC), and apatite (20 wt%), wollastonite (55 wt%), and whitlockite (15 wt%) (designated A.W.CP-GC) were prepared. They were implanted into the tibia of mature male rabbits for 5 days, 10 days, 20 days, 30 days, 60 days, 6 months, and 12 months. All three types of glass-ceramics showed direct bonding to the bone 30 days after implantation. It was observed by SEM-EPMA 30 days after implantation that Si and Mg content decreased, P content increased, and Ca content did not change across the reactive zone from the glass-ceramics to bone. The level of P and Si in the A.W.CP-GC changed five days after implantation. In A.W-GC and A-GC, a little change in P and Si levels was observed between 10 and 20 days after implantation. The width of reactive zone was narrowest with A-GC, wider with A.W-GC, and widest with A.W.CP-GC. The dissolution of glass-ceramics stopped 6 months after implantation. This phenomenon shows that the glass-ceramics may be suitable for clinical use.
The expression of a LEU gene from Candida maltosa (designated as C-LEU2) isolated previously (Kawamura et al. 1983) was shown to be regulated, when transferred into Saccharomyces cerevisiae, by leucine and threonine in the medium, as in the case of LEU2 gene of S. cerevisiae. The coding region together with the regulatory region was subcloned and the nucleotide sequence was determined. When the sequence of the coding region was compared with that of LEU2, the homology was 72% for base pairs and 76% for deduced amino acids. Comparison of the regulatory region of C-LEU2 with those of LEU1 and LEU2 suggested a few short consensus sequences which are involved in regulation of gene expression by leucine and threonine in the medium.
Types 1 and 2C fibers in human skeletal muscle were cross-reactively identified with monoclonal anti-bovine neurofilament (200 kd) antibody. Thirty seven biopsy samples including sixteen vastus lateralis muscles, twelve lumbar paravertebral muscles, six gluteus medius muscles, two flexor carpi ulnaris muscles, and one flexor pollicis longus muscle, were examined. Serial transverse sections were stained histochemically with myofibrillar ATPase (pH 10.4, 4.6, 4.3) and DPNH-tetrazolium reductase reactions, and immunochemically using the avidin-biotin-peroxidase complex with the primary antibodies of monoclonal anti-bovine neurofilament (200 kd, 160 kd, 70 kd) antibodies and anti-bovine glial filament acidic protein antibody. The immunochemical reaction with anti-NF (200 kd) antibody could distinguish two kinds of fibers; positive and negative in all of the specimens. No fiber was recognized with other antibodies. Myosin ATPase reactions in serial sections proved that the positively stained fibers with anti-NF (200 kd) antibody were types 1 and 2C fibers and negative fibers types 2A and 2B fibers. At present, it is not known what substance is responsible for the cross-reaction with the monoclonal anti-NF (200 kd) antibody in types 1 and 2C fibers, but this unique antibody would be valuable in two aspects: one concerns the problem of the evolution of fiber types, and the other the utility as another supplemental method to conventional myosin ATPase scheme.
Monkey periodontal ligaments have been examined at the ultrastructural level to demonstrate the nature of reactive sites in oxytalan fibres. The high iron diamine (HID) and HID-thiocarbohydrazide-silver proteinate methods specific for sulphate groups, with and without prior oxidation with monopersulphate, were used. Oxytalan fibres were composed of bundles of microfibrils with a diameter of 11.5 +/- 1.7 nm (mean +/- S.D., n = 50). In cross section the microfibrils were found to have a denser periphery, giving them a 'tubular' appearance. The oxytalan microfibrils of non-oxidized specimens showed little reactivity with either HID method, except that the extracellular matrix material in close association with collagen fibrils stained weakly; in oxidized specimens, both HID methods strongly stained oxytalan microfibrils and weakly stained the extracellular matrix material. Such reactivity of oxytalan microfibrils was not altered by digestion with testicular hyaluronidase or chondroitinase ABC, performed prior to or after persulphate oxidation. Further, the sequential thiosulphation and HID method for the demonstration of disulphide and sulphhydryl groups stained oxytalan fibres moderately. These results indicate that the oxidative generation of sulphate groups in oxytalan fibres may occur from either disulphide or sulphhydryl groups, or both, rather than the result of unmasking of sulphated glycosaminoglycans.
Aldosterone secretion may be inhibited by potassium depletion, inhibitors of the renin-angiotensin system, dopamine and atrial natriuretic factor. The latter appears to be an important physiological regulator of aldosterone secretion. ANF inhibits basal, ACTH, Angiotensin II and potassium-stimulated aldosterone production in vitro by a direct action on the adrenal gland. In vivo data also support a direct inhibitions of aldosterone. The stimulation of aldosterone secretion by infusions of Angiotensin II and potassium is inhibited by simultaneous infusions of ANF. Infusions of ANF lower the basal aldosterone secretion in man. The mechanism by which ANF inhibits aldosterone is not known. No unifying first step has been identified to explain ANF's ability to inhibit all stimuli. In vivo, part of the lowering of aldosterone levels may be due to inhibition of renin secretion. This effect of ANF upon renin is inconsistent and appears to depend upon the experimental conditions.