We have produced three kinds 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). They contain different crystal combinations and have different mechanical properties. The first glass ceramic (A-GC) was prepared by heating a glass plate to 870 degrees C. It contains only oxy- and fluoroapatite (35 wt%). The second glass ceramic (A-W-GC), and the third (A-W-CP-GC), were prepared by heating glass powder compacts to 1050 degrees C and 1200 degrees C, respectively. A-W-GC contains oxyapatite and fluoroapatite (Ca10(PO4)6(O,F2] (35 wt%) and beta-wollastonite (40 wt%). A-W-CP-GC contains oxyapatite and fluoroapatite (20 wt%), beta-wollastonite (CaO X SiO2) (55 wt%), and beta-whitlockite (3CaO X P2O5) (15 wt%). The bending strengths of A-GC, A-W-GC, and A-W-CP-GC were 88MPa, 178MPa, and 213MPa, respectively, in air. Rectangular ceramic plates (15mm X 10mm X 2mm) were implanted into a rabbit tibia. Ten and 25 weeks after implantation, the segment of tibia with implant was excised for examination. The segment was held by a special jig and the traction breaking load (failure load) was measured by an autograph. A-GC showed a lower load than A-W-GC and A-W-CP-GC. The loads for A-W-GC and A-W-CP-GC were almost equal. The failure loads did not change significantly between 10 and 25 weeks for any of the materials. The interface was examined by Giemsa surface staining, contact micro-radiography, and SEM-EPMA. Giemsa surface staining and CMR revealed direct bonding between the materials and the bone for all the three materials. SEM-EPMA showed that Si and Mg content decreased, Ca content did not change, and P content increased at the reaction zone between all three glass ceramics and bone. This was observed at 10 weeks, as well as at 25 weeks, after implantation. The reaction zone was narrowest with A-GC, wider with A-W-GC, and widest with A-W-CP-GC.

Animals↗

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Repair of congenital ascending aortic aneurysm.

We report a case of congenital ascending aortic aneurysm associated with double-outlet right ventricle that has been successfully repaired by graft replacement and extracardiac total cavo-pulmonary connection.

Aortic Aneurysm, Thoracic↗

PubMedDate not supplied

Mouse spot tests with alkylnitrosoureas.

Spot tests with various alkylnitrosoureas were carried out using the newly established PW strain of male and female C57BL/6 mice. Chemicals tested were N-methyl-N-nitrosourea (MNU), N-ethyl-N-nitrosourea (ENU), N-propyl-N-nitrosourea (PNU) and N-butyl-N-nitrosourea (BNU). Although MNU had a severe teratogenic effect, no clearly positive color spot was obtained, while apparent induction of their color spots was observed with ENU, PNU and BNU. The frequency of appearance of these color spots was dose-dependent. In F1 males from the treated group, the weight of the testes was significantly lower in mice about 30 days old. It is suggested that these chemicals may have mutagenic effects on both developing somatic and germ cells of mice.

Animals↗

PubMedDate not supplied

Genetic analysis of an N-ethyl-N-nitrosourea-induced mutation at the hemoglobin beta-chain locus in mice.

The specific-locus test was performed with N-ethyl-N-nitrosourea (ENU) on spermatogonia of mice by using visible loci and a hemoglobin beta-chain (Hbb) locus. Male wild-type (C3Hf/He) mice were injected intraperitoneally with ENU. 8 weeks after injection, these males were mated with tester strain females (PW). 9 visible mutants and the 1 Hbb locus mutant were obtained. This Hbb locus mutation was heritable and viable under homozygous conditions, suggesting that it might have resulted from events at the molecular level.

Animals↗

PubMedDate not supplied

Safety studies of a novel starch, pullulan: chronic toxicity in rats and bacterial mutagenicity.

This study was designed to assess the potential toxicity of pullulan, a starch-like substance produced by Aureobasidium pullulans that is proposed for use as a texturizer for meat and meat substitutes and as a flavour substrate. Sprague-Dawley rats (15/sex/group) were administered pullulan as a dietary admixture at levels of 1, 5 and 10% for a period of 62 wk. Control animals (15/sex) received untreated standard laboratory diet. The feeding study, originally intended to continue for 24 months, was terminated at 62 wk due to poor survival resulting from intercurrent pneumonia which was confirmed by histological findings. At 62 wk of treatment, all survivors were killed, complete gross post-mortem examinations were conducted on all animals, selected organs were weighed and organ/body weight and organ/brain weight ratios calculated. Mean body weights of all treated groups were comparable to controls. There were no indications of an adverse effect of pullulan on food consumption or food efficiency. At termination of the study, haematology and clinical chemistry values of treated animals were comparable to control values. There was no indication of pullulan-related toxicity in terminal organ and body weights. Macroscopic and microscopic examinations revealed no toxic lesions due to treatment. The mutagenicity of pullulan was assessed with and without metabolic activation in Salmonella typhimurium (TA100, TA1535, TA98 and TA1537). Pullulan did not increase the number of revertants per plate in any strain at any dose, including 10,000 micrograms/plate with or without metabolic activation, suggesting that it lacks mutagenic/carcinogenic potential on the basis of these results, it is concluded that pullulan lacks significant toxicological activity. The no-observed-adverse-effect level was 10% (equal to or greater than 4450 mg/kg body weight/day in males and 5080 mg/kg body weight/day in females) which would support use in various foods as a substrate for flavours.

Administration, Oral↗

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Effects of parathyroid hormone and related polypeptides on the heart and coronary circulation of dogs.

The effects of parathyroid hormone and related polypeptides on the heart were examined using the canine heart-lung preparation supported by a donor. Synthetic bovine parathyroid hormone (PTH) containing 34 amino acids [PTH-(1--34)] and natural bovine PTH containing 84 amino acids [PTH-(1--84)] showed slight positive chronotropic and inotropic action and prominent coronary vasodilator action. The effects of the two compounds were very similar. The cardiac stimulatory action was not blocked by pindolol. The coronary vasodilation occurred without increase in the myocardial oxygen consumption, suggesting that it is due to a direct action on the coronary vasculature. All effects occurred soon after intra-arterial injection, lasted only about 20 min, and were not accompanied by changes in plasma Ca and Pi levels. Fragments of PTH, PTH-(24--34) containing 11 amino acids. PTH-(24--28) containing 5 amino acids, and PTH-(25--27) containing 3 amino acids showed very weak transient coronary dilatory action without cardiac stimulatory effects.

Animals↗

PubMedDate not supplied

Effective plasma concentrations of antiarrhythmic drugs against sustained halothane-adrenaline arrhythmia in dogs.

We determined the minimum effective plasma concentrations of several antiarrhythmic agents against canine halothane-adrenaline arrhythmia. Sustained ventricular tachycardia was produced by continuous adrenaline infusion at rates of 1.5 to 4 micrograms/kg/min under 1.5% halothane anesthesia. Procainamide, 20 mg/kg, produced ventricular fibrillation in three of nine dogs. Disopyramide, 3 mg/kg, suppressed the arrhythmia in nine of 11 dogs at a minimum effective plasma concentration of 4.2 micrograms/ml, but produced ventricular fibrillation in the remaining two dogs. Phenytoin, 5 mg/kg, was effective at a minimum concentration of 12 micrograms/ml. Lidocaine, 10 mg/kg, suppressed the arrhythmia at a minimum concentration of 15 micrograms/ml, which is much higher than the human toxic plasma level. These drugs may have suppressed the adrenaline arrhythmia by inhibiting the sodium channel, because their effective concentrations were very close to membrane-stabilizing concentrations in vitro. Small doses of 30 micrograms/kg propranolol and 0.1 mg/kg N-696, two beta-blockers, and 0.1 mg/kg verapamil, a calcium channel blocker, yielding a concentration of 0.03 micrograms/ml, suppressed the arrhythmia, probably by indirectly or directly blocking the calcium channel.

Animals↗

PubMedDate not supplied

A rupture of lung metastasis of hepatocellular carcinoma causing haemothorax.

A 67 year old male with non-resectable hepatocellular carcinoma (HCC) in both lobes and liver cirrhosis was treated with transcatheter arterial embolization and regional chemotherapy. He was doing well for 18 months. He was readmitted for fever, chest pain and multiple pulmonary metastases. During interleukin-2 therapy, he suddenly developed dyspnoea and palpitation, and was in shock. Left-sided haemothorax was confirmed by draining 3 L of fresh blood. In spite of intensive care, he died within 36 h. Autopsy showed that the haemothorax was caused by rupture of one of the metastases in the upper lobe of the left lung, and that the primary HCC was totally necrotic. Survey of the literature failed to find a report of fatal bleeding from a lung metastasis of HCC.

Aged↗