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Biomedical subjects

M Chiba

Publications and source records attributed to M Chiba.

468 records · Page 26Linked to original sources
PubMedDate not supplied

Experimental study on interactions between selenium and tin in mice.

The organ distributions of tin and selenium, and their excretion into urine and feces, were determined in mice. There were four groups; (A) control, (B) Sn (5 mumol/kg/d) ip injection, (C) Se (5 mumol/kg/d) sc injection, and (D) Sn plus Se (5 mumol/kg/d, each). Animals received injections once a day for 12 consecutive days. The results were the following (1) Simultaneous injection of Sn and Se enhanced accumulation of both elements in the body, i.e., in group B, 14.1% of the total injected amount of Sn was excreted into urine and feces; in group C, 46.2% of total injected Se was excreted into urine and feces; in group D, 10.9% of total Sn and 37.5% of total Se were found in excreta. (2) Large amounts of Sn were found in bone, liver, spleen, and kidney in group B. When Se was administered jointly with Sn, the concentrations of Sn in bone and liver were suppressed, whereas those in spleen and pancreas were increased. (3) The effects of Se-injections at this dose on concentrations of Se in organs were small. (4) In plasma, chemical reduction of selenite by stannous chloride was not observed.

Animals↗
PubMedDate not supplied

Impairment of debrisoquine 4-hydroxylase and related monooxygenase activities in the rat following treatment with propranolol.

The effect of repetitive oral administration of propranolol on hepatic microsomal drug metabolizing enzyme activities in the rat was investigated. Propranolol ring (4-, 5- and 7-)hydroxylase activities were markedly decreased, but, interestingly, N-desisopropylase activity was increased after propranolol administration. A marked decrease in enzyme activity after propranolol pretreatment was also observed with debrisoquine 4-hydroxylation. In addition, a similar decrease was observed with imipramine 2-hydroxylation which co-segregates with debrisoquine/sparteine type polymorphic drug oxidation, but not with imipramine N-demethylation. These results suggest the selective impairment of debrisoquine 4-hydroxylase by propranolol pretreatment.

Animals↗
PubMedDate not supplied

Mechanical responses of the periodontal ligament in the transverse section of the rat mandibular incisor at various velocities of loading in vitro.

Stress-strain curves of the periodontal ligament (PDL) were obtained at various velocities of extrusive loading of 1, 10, 10(2), 10(3) and 10(4) mm/24 h in vitro. Significant increases of the maximum shear stress, tangent modulus and failure strain energy density were found with increases in the velocity of loading. The maximum shear strain increased from a velocity of 1 to 10 mm/24 h but decreased from 10 to 10(4) mm/24 h. It was shown histologically that the free surface of the PDL adhering to the cementum after mechanical testing was rough and irregular at higher velocities and rather smooth at lower velocities. These results showed that the mechanical properties and mode of failure of the rat incisor PDL were greatly dependent on the strain rate. It is possible that the PDL of the continuously erupting rat incisor has mechanical characteristics favourable for resisting weakly to slow and small eruptive forces but strongly to the fast and large occlusal forces as suggested previously [Chiba and Komatsu, The Biological Mechanisms of Tooth Eruption and Root Resorption (1988)].

Alveolar Process↗
PubMedDate not supplied

Protective effect of selenium on the inhibition of erythrocyte 5-aminolevulinate dehydratase activity by tin.

The protective effect of selenium (Se) on the inhibition of erythrocyte 5-aminolevulinate dehydratase (ALAD) activity by tin (Sn) was examined in mice. When mice were intraperitoneally (i.p.) administered 10 mumol/kg of stannous chloride, the activity of erythrocyte ALAD decreased to 35% of control. When more than an equimolar dose of sodium selenite was injected i.p. simultaneously with Sn, the ALAD activity was completely protected. Mortalities and weight gains of mice treated with Se were also reduced when Sn was administered simultaneously.

Animals↗
PubMedDate not supplied

Degradation of porous poly(anhydride-co-imide) microspheres and implications for controlled macromolecule delivery.

The degradation properties of porous microspheres made using a new family of polyanhydride copolymers, the poly(anhydride-co-imides), were studied. Poly[trimellitylimido-L-tyrosine-co-sebacic acid-co-1,3-bis(carboxyphenoxy)propane] microspheres, with and without entrapped bovine serum albumin (BSA) as a model protein, were made using the double emulsion solvent evaporation process. Water penetration and anhydride bond cleavage (polymer degradation) occurred rapidly (< 5 days) compared to the time scale of overall microsphere erosion (weeks to months) with most polymer compositions. Subsequent to bond cleavage, the ultimate erosion of the microsphere and release of entrapped BSA was due mainly to the slow dissolution of the individual hydrophobic monomers (TMA-Tyr, SA and CPP) from the microsphere surface. BSA was released at approximately the same rate as the polymer eroded. Due to the fast degradation of anhydride bonds relative to microsphere erosion, initial polymer molecular weight did not have a significant effect on macromolecule release rates. Instead, monomer solubility correlated well with polymer erosion and BSA release rates. This erosion mechanism leads to predictable drug release rates which may be appropriate for the delivery of many protein therapeutics, including vaccine antigens. The anhydride-imide copolymers were well tolerated in acute toxicity studies in rats and therefore show promise as biomaterials.

Animals↗
PubMedDate not supplied

Influence of bone mineral density on pedicle screw fixation: a study of pedicle screw fixation augmenting posterior lumbar interbody fusion in elderly patients.

BACKGROUND CONTEXT: Some biomechanical studies have demonstrated that bone mineral density of the lumbar spine (BMD) affects the stability of pedicle screws in vitro. PURPOSE: To investigate influence of BMD on loosening and related failure of pedicle screws in vivo. STUDY DESIGN/SETTING: A clinical study of 52 patients who underwent pedicle screw fixation augmenting posterior lumbar interbody fusion (PLIF). PATIENT SAMPLE: There were 13 men and 39 women, with an average age of 63 years (range, 45-76 years) at the time of operation. The mean follow-up period was 2.8 years (range, 2-6 years). OUTCOME MEASURES: Relationship between BMD, screw loosening, and its related failures were statistically analyzed. METHODS: BMD was measured by the dual energy X-ray absorptiometry (DEXA) method. Radiographic assessments were done by the first author and independently by another orthopedist who was not informed of the values of BMD. RESULTS: The mean BMD of all patients was 0.879 +/- 0.215 (mean +/- S.D.) g/cm2. The mean BMD in patients with and without screw loosening was 0.720 +/- 0.078 g/cm2 (n=11) and 0.922 +/- 0.221 g/cm2 (n=41). There was a significant difference between the mean BMD of patients with and without screw loosening (P<.01). The mean BMD of patients with "union," "nonunion" and "undetermined union" was 0.934 +/- 0.210 g/cm2 (n=40), 0.674 +/- 0.104 g/cm2 (n=4) and 0.710 +/- 0.116 g/cm2 (n=8), respectively. The mean BMD of patients with "union" was significantly greater than those with "nonunion" and "undetermined union" (P<.05). CONCLUSION: It could be concluded that BMD has a close relation with the stability of pedicle screws in vivo, and BMD value below 0.674 +/- 0.104 g/cm2 suggests a potential increased risk of "nonunion" when pedicle screw fixation is performed in conjunction with PLIF.

Age Factors↗
PubMedDate not supplied

Determination of tin in biological materials by atomic-absorption spectrometry with a graphite furnace.

The determination of tin in the blood, liver, kidney, and spleen by atomic-absorption measurement using a graphite furnace was investigated. The presence of 20 micrograms/mL Fe(III) reduced absorbance of 0.2 microgram/mL Sn to 50%. To remove the interference of Fe(III), it was reduced to Fe(II) by 10% ascorbic acid, and Sn(IV) was extracted by methylisobutylketone (MIBK) without a chelating agent. This technique can be applied when 100 micrograms/mL Fe coexists with 0.2 microgram/mL Sn. Four methods for determination of tin in the blood were examined: (a) standard addition, (b) low-temperature ashing/MIBK extraction, (c) wet ashing/MIBK extraction, and (d) direct determination. The results of (a), (b), and (c) showed a high correlation (r greater than 0.86, n = 12), while the values obtained by (d) were scattered widely and showed little correlation with those determined by the other three methods. In methods (b) and (c), the detection limit was 10 ng/mL (0.2 ng Sn) without expansion mode, 2 ng/mL (0.04 ng Sn) with X 5 expansion mode, the recovery more than 90%, and the coefficient of variation 6.6% (n = 8). Method (c) was recommended for large sample sizes, and was also suitable for determination of tin in liver, kidney, and spleen, using 0.5%, instead of 10%, ascorbic acid.

Animals↗
PubMedDate not supplied

Determination of terbium in organs of mice administered terbium chloride: comparative study of fluorometry and atomic absorption spectrometry.

The determination of terbium (Tb) in organs by fluorometry and atomic absorption spectrometry (AAS) was investigated. The organs of mice were ashed before the instrumental applications. The fluorometric measurement of Tb was performed after formation of a complex with dipicolinate. The detection limit was 0.1 micrograms/mL and the coefficient of variation was less than 5% (N = 6). AAS measurement of Tb was carried out with a pyrolytic graphite furnace. The detection limit by AAS was 1 microgram/mL. The concentrations of Tb in various organs of mice intraperitoneally administered TbCl3 at doses of 10, 50, and 250 mg Tb/kg were measured by both methods. The values obtained from each organ were dependent on the dose. High concentrations of Tb were found in spleen, pancreas, and seminal vesicle; lesser amounts were found in liver and testis. The correlation coefficient for both methods was high; r = 0.991 (N = 20) in liver and r = 0.988 (N = 20) in pancreas.

Animals↗
PubMedDate not supplied

Determination of germanium in human specimens: comparative study of atomic absorption spectrometry and microwave-induced plasma mass spectrometry.

The determination methods of germanium (Ge) in biological specimens such as blood plasma, erythrocytes, urine, hair, nail, and other organs were established using graphite furnace atomic absorption spectrometry (GFAAS) and microwave-induced plasma mass spectrometry (MIP-MS). The detection limits of Ge standard solution were 3 ng/mL with GFAAS and 0.05 ng/mL with MIP-MS. The detection limits in organ samples depended on the type of samples and sampling amounts: 3-30 ng/g by GFAAS and 0.05-0.5 ng/g by MIP-MS. The sensitivity of GFAAS was lower than that of MIP-MS; however, it was adequate for determining Ge concentrations in specimens from patients who had ingested Ge. Samples were digested by a simple wet-ashing procedure using nitric acid and perchloric acid. To avoid the interfering effects of coexisting elements and perchloric acid residue, an extraction method using organic solvent was tried. When using MIP-MS, extraction was not necessary; however, both dilution and addition of an internal standard were needed. Special attention was required for iron-rich samples because a molecular ion of 56Fe16O was observed at nm/z72 where 2Ge was monitored. The results of Ge concentrations in human samples obtained by these methods agreed well. Interfering effects of perchloric acid, which was used for digestion and which remained in samples, were observed in both methods. Hair and nail samples from people who had ingested Ge were useful for monitoring Ge in the body. Hair samples were useful for determining past exposure to Ge when the distribution patterns from the scalp to the end of the strand were analyzed. In control subjects, Ge concentrations in the listed specimens and organs were lower than 0.1 microg/g or mL, and these low levels of Ge were able to be determined by MIP-MS in combination with the extraction method.

Aged↗
PubMedDate not supplied

Simplified cleanup and liquid chromatographic determination of oxamyl residues in potato tubers.

A simple and efficient method is presented for the extraction, cleanup, and liquid chromatographic (LC) determination of oxamyl residues in potato tubers. Samples are extracted with methanol, partitioned into dichloromethane, and cleaned up using Sep-Pak Florisil cartridges. LC determination is performed using a Zorbax PSM 60 size exclusion column with an acetonitrile-water (1 + 9) mobile phase and UV detection at 254 nm. Recovery of oxamyl from spiked control tubers averaged 94.1 and 85.9% at fortification levels of 0.4 and 0.08 micrograms oxamyl/g tuber, respectively. The minimum detectable concentration of oxamyl by this method is 0.01 micrograms/g.

Carbamates↗
PubMedDate not supplied

Successful modified Senning operation for the repair of Taussig-Bing malformation.

Surgical correction was carried out successfully in a severely cyanotic 3-year-old boy with Taussig-Bing malformation. The cardiac anomaly was associated with semilunar valves side by side, and at the same height, a bilateral conus without pulmonary-mitral continuity and subpulmonary ventricular septal defect, on which pulmonary valve overode. The surgical correction consisted of the closure of the VSD by a right atrial approach and modified Senning procedure under profound hypothermic cardiac arrest with surface cooling and limited cardiopulmonary bypass. The patient survived operation and was doing well 10 months after surgery. To our knowledge, no other identical case with Taussig-Bing malformation has been corrected successfully by this procedure nor has previously been reported.

Cardiopulmonary Bypass↗
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Enhancement of ectopic bone formation in mice with a deficit in Fas-mediated apoptosis.

Bone formation is under the control of cytokines as well as growth factors such as bone morphogenetic proteins (BMP). This suggests the possibility that osteogenesis might be modulated by factors which also modulate the immune system. To test whether immune disorders in the host may influence bone formation, we studied BMP-induced bone formation in a C3H/HeJ strain of mice bearing a mutant gene, the lymphoproliferation gene (lpr) or the generalized lymphoproliferative disease gene (gld), both of which are known to be a Fas deletion mutant and a Fas ligand mutant, respectively, and to induce immune disorders via a deficit in Fas-mediated apoptosis. Crude BMP derived from bovine bone were injected into the muscular tissue in the femur of adult C3H/HeJ mice or C3H/HeJ mice bearing an lpr or gld gene. Quantitative analysis of the resulting ectopic bone formation by X-ray photography 2 weeks after injection revealed that the presence of either the lpr or gld gene caused a bone mass significantly larger in dimension than that seen in the wild type mice. Histological examination also revealed the different influence between these mutant genes on the level of bone formation exhibited by hyaline cartilage and bone trabeculae. Based on these results, we discussed the possible mechanisms of the enhanced ectopic bone formation under the deficit in Fas-mediated apoptosis.

Animals↗