Microscopic and crystallographic examinations of the teeth of the X-linked hypophosphatemic mouse

Teeth from the C57BL/6J-Hyp mouse (Hyp mouse) were examined histologically, radiographically, and crystallographically. Microscopic examinations of the ground sections, the decalcified and H-E-stained sections, and the contact microradiograms of molars and incisors from the Hyp mouse showed several abnormalities--such as large pulp chamber, wide predentin, thin dentin at the pulp floor, and multiple occurrences of interglobular dentin. Powder and microbeam x-ray diffraction analyses showed that the crystallinity of hydroxyapatite in incisor globular dentin from the Hyp mouse was higher than that in incisor dentin from the normal mouse. On the other hand, the findings of transmission electron microscopy demonstrated that the sizes of hydroxyapatite crystals of globular dentin in the Hyp incisor were larger than those in normal incisor dentin. These results demonstrated that the findings in Hyp mouse teeth were in accord with those of human XLH teeth.     

Crown dilaceration of a first premolar caused by extraction of its deciduous predecessor: a case report

This report describes a rare case of crown dilaceration of the mandibular first premolar caused by trauma during extraction of the precedent primary first molar. The mandibular first primary molar had been extracted at the age of 4 years 7 months. Compared to the pre-operative radiograph, the post-operative film showed that the direction of the first premolar tooth germ had changed, suggesting that crown dilaceration had been induced by the surgical procedures during tooth extraction. From radiographic examinations, the premolar was considered to have erupted spontaneously.     

Effects of hyposalivation on the oral microflora of rats fed sucrose or wheat flour diets.

The effects of hyposalivation on the induction of dental caries and on the composition of the oral microflora were examined in specific pathogen-free Sprague-Dawley rats fed either a sucrose or a wheat flour diet with or without inoculation of Streptococcus mutans. Significant dental caries was induced in hyposalivated rats fed diet 2000 containing 56% sucrose, irrespective of infection by S. mutans. Diets containing 56% wheat flour did not induce dental caries in either hyposalivated or sham-operated rats, irrespective of infection by S. mutans. Bacteriological examinations at the end of the experiment demonstrated that the total numbers of lactobacilli and staphylococci increased in hyposalivated rats irrespective of the diet given, while the inoculated stain of S. mutans decreased significantly in hyposalivated rats. These findings suggest that some acidogenic microorganisms such as lactobacilli and staphylococci that can utilize sucrose or glucose but not wheat flour may also promote dental caries in hyposalivated rats.     

Caries inhibitory activity of cacao bean husk extract in in-vitro and animal experiments

Cacao bean husk extract (CBH) was examined for inhibitory effects on the caries-inducing properties of mutans streptococci in vitro and on caries development in specific pathogen-free Sprague-Dawley rats infected with mutans streptococci. CBH reduced the growth rate of almost all oral streptococci examined, which resulted in the reduction of acid production. Furthermore, insoluble glucan synthesis by the glucosyltransferases from Streptococcus mutans MT8148R and Streptococcus sobrinus 6715 was significantly inhibited by CBH. Hence, the sucrose-dependent cell adherence of mutans streptococci was also depressed by CBH. The administration of CBH in drinking water resulted in significant reductions of caries development and dental plaque accumulation in rats infected with either Strep. sobrinus 6715 or Strep. mutans MT8148R, and the minimum cariostatic concentration was 1.0 mg/ml. These results indicate that CBH possesses powerful anticariogenic potential.     

Long-term antihypertensive drug use and risk of cancer: The Japan Public Health Center-based prospective study

Antihypertensive drugs have been reported as both promotors and suppressors of cancers and this relationship has been known for several decades. We examined a large-scale prospective cohort study in Japan to assess the relationship between long-term antihypertensive drug use, for 10 y, and carcinogenesis. We divided participants into 4 categories according to the period of antihypertensive drug use, and calculated the hazard ratios (HRs), 95% confidence intervals (CIs), and P trends using the Cox proportional hazard model. In all cancers, there was a significant difference in the medication period and the adjusted HR, as well as a significant difference in the P trend. Furthermore, more than 10 y use of antihypertensive drugs significantly increased the adjusted HR in colorectal cancer (multivariable HR: 1.18, 95% CI: 1.01-1.37 in the >10 y use group; P for trend = .033) and renal cancer (multivariable HR: 3.76, 95% CI: 2.32-6.10 in the 5-10 y use group; multivariable HR: 2.14, 95% CI: 1.29-3.56 in the >10 y use group; P for trend < .001). The highest adjusted HR in renal cancer among antihypertensive drug users was observed in the analysis performed on patients in which the outcomes were calculated from 3 y after the 10-y follow-up survey and by sex. A large-scale cohort study in Japan suggested that long-term use of antihypertensive drugs may be associated with an increased incidence of colorectal and renal cancer.     

Characteristic Sonographic Findings of Early Restenosis After Carotid Endarterectomy

Objective. Restenosis of the carotid artery after carotid endarterectomy (CEA) is a major complication. The frequency, time of occurrence, and tissue characteristics of carotid restenosis were assessed with sonography. Methods. Two hundred sixteen patients who had CEA for carotid stenosis were studied; follow‐up sonography and magnetic resonance angiography were done 2 weeks, 3 months, and then every year after CEA. On sonography, restenosis was defined as an internal carotid artery (ICA) with a peak systolic velocity of 170 cm/s or greater or a maximum area of stenosis of 90% or greater. Results. During 605 artery‐years of follow‐up, 18 patients (7.5%) were found to have restenosis on sonography: 4 at 3 months, 11 at 1 year, and 3 at 2 years after CEA. At the time that restenosis was detected, in all 18 ICAs the peak systolic velocity exceeded 200 cm/s and had more than doubled since the last measurement (mean ± SD, 103 ± 27 to 321 ±107 cm/s), whereas the area of stenosis exceeded 90% in 6 patients, and magnetic resonance angiography revealed stenosis of 60% or greater in 8 patients. On sonography, all of the restenotic plaques were isoechoic and concentric. The restenosis was asymptomatic in 17 patients. Vascular risk factors or the severity of initial carotid stenosis before CEA were not associated with development of restenosis. Eleven patients had successful endovascular therapy, and the others received medical treatment. Conclusions. A marked increase in the flow velocity through an operated ICA is a good indication of restenosis. The isoechogenicity and concentricity of the restenotic plaques suggest that the restenosis is primarily the result of intimal hyperplasia.     

Magnetic resonance spectroscopy and its clinical applications in multiple sclerosis

Proton magnetic resonance spectroscopy(1H-MRS), which provides biochemical information in not only visible lesions on conventional MR imaging but also normal appearing white matter(NAWM), has extended the genesis of multiple sclerosis(MS) in several important directions. First, serial 1H-MRS studies reveal dynamic regional biochemical alterations in plaques during the course of the illness. Second, axonal damage may occur at early stage. Third, neuronal loss can be substantial in the gray matter. Fourth, NAWM shows widespread biochemical involvement prior to detection on MRI. Fifth, severities of neuroaxonal involvement significantly correlate with neurological dysfunction. 1H-MRS will provide more detailed information than conventional MRI, and could be beneficial in monitoring effects of therapeutic interventions in MS.