Differentiation of Apical Bud Cells in a Newly Developed Apical Bud Transplantation Model Using GFP Transgenic Mice as Donor

Rodent mandibular incisors have a unique anatomical structure that allows teeth to grow throughout the lifetime of the rodent. This report presents a novel transplantation technique for studying the apical bud differentiation of rodent mandibular incisors. Incisal apical end tissue with green fluorescent protein from transgenic mouse was transplanted to wild type mice, and the development of the transplanted cells were immunohistologically observed for 12 weeks after the transplantation. Results indicate that the green fluorescent apical end tissue replaced the original tissue, and cells from the apical bud differentiated and extended toward the incisal edge direction. The immunostaining with podoplanin also showed that the characteristics of the green fluorescent tissue were identical to those of the original. The green fluorescent cells were only found in the labial side of the incisor up to 4 weeks. After 12 weeks, however, they were also found in the lingual side. Here the green fluorescent cementocyte-like cells were only present in the cementum close to the dentin surface. This study suggests that some of the cells that form the cellular cementum come from the apical tissue including the apical bud in rodent incisors.     

Beneficial effect of beraprost sodium plus telmisartan in the prevention of arterial stiffness development in elderly patients with hypertension and cerebral infarction

Beraprost sodium (BPS, an analogue of prostacyclin) and telmisartan (TS, an angiotensin receptor blocker) have been reported to have a preventive effect on arterial stiffness in patients with cardiovascular diseases. The purpose of this study was to estimate the effects of a combined therapy using BPS and TS on arterial pulse wave velocity (PWV) values in elderly patients with hypertension and cerebral infarction. Over a 3-month period, 80 subjects with hypertension and histories of cerebral infarction received BPS only (120 microg/day p.o.), TS only (40 mg/day p.o.), both BPS and TS, or no medication at all (control). Arterial PWV and ankle brachial indices (ABI) were determined prior to and after 3 months of drug administration. During the follow-up, there were no significant changes in any of the parameters monitored with the exception of a significant decrease in systolic blood pressure in the BPS only, TS only, and BPS plus TS groups when compared to controls. The difference values for PWV in the control group, BPS only group, TS only group, and BPS plus TS group were +232.5, -114.6, -151.5, and -248.1 cm/s, respectively. The reduction values were significantly more pronounced in the BPS plus TS group than in the BPS only (P=0.037) and the TS only (P=0.022) groups. When BPS is combined with TS, an overall additive effect is seen in the improvement of PWV in Japanese patients with hypertension and cerebral infarction. This combination therapy is more beneficial than the corresponding monotherapies.     

Imaging myocardial metabolism

The prevalence of coronary artery disease and heart failure is increasing in modern industrialized countries, fueling the search for novel therapies. Because metabolism and function in the heart are inextricably linked, energy substrate metabolism has provided a potential target for novel therapies and the development of technologies to image myocardial metabolism has been crucial in establishing new therapeutic approaches. Nuclear imaging probes have been used to successfully evaluate aerobic fatty acid metabolism, anaerobic glucose metabolism, and oxidative metabolism and can be used for the accurate, sensitive, and physiological evaluation of therapeutic effects. More recently, with the advent of stem-cell technologies, imaging approaches have been employed to track the fate of stem cells and to monitor the success of these treatments. In the future, our ability to image myocardial metabolism is likely to assist the development of other new therapies to improve the function of the failing heart.     

Profiles of purine biosynthesis, salvage and degradation in disks of potato (Solanum tuberosum L.) tubers

To find general metabolic profiles of purine ribo- and deoxyribonucleotides in potato (Solanum tuberosum L.) plants, we looked at the in situ metabolic fate of various ¹⁴C-labelled precursors in disks from growing potato tubers. The activities of key enzymes in potato tuber extracts were also studied. Of the precursors for the intermediates in de novo purine biosynthesis, [¹⁴C]formate, [2-¹⁴C]glycine and [2-¹⁴C]5-aminoimidazole-4-carboxyamide ribonucleoside were metabolised to purine nucleotides and were incorporated into nucleic acids. The rates of uptake of purine ribo- and deoxyribonucleosides by the disks were in the following order: deoxyadenosine > adenosine > adenine > guanine > guanosine > deoxyguanosine > inosine > hypoxanthine > xanthine > xanthosine. The purine ribonucleosides, adenosine and guanosine, were salvaged exclusively to nucleotides, by adenosine kinase (EC 2.7.1.20) and inosine/guanosine kinase (EC 2.7.1.73) and non-specific nucleoside phosphotransferase (EC 2.7.1.77). Inosine was also salvaged by inosine/guanosine kinase, but to a lesser extent. In contrast, no xanthosine was salvaged. Deoxyadenosine and deoxyguanosine, was efficiently salvaged by deoxyadenosine kinase (EC 2.7.1.76) and deoxyguanosine kinase (EC 2.7.1.113) and/or non-specific nucleoside phosphotransferase (EC 2.7.1.77). Of the purine bases, adenine, guanine and hypoxanthine but not xanthine were salvaged for nucleotide synthesis. Since purine nucleoside phosphorylase (EC 2.4.2.1) activity was not detected, adenine phosphoribosyltransferase (EC 2.4.2.7) and hypoxanthine/guanine phosphoribosyltransferase (EC 2.4.2.8) seem to play the major role in salvage of adenine, guanine and hypoxanthine. Xanthine was catabolised by the oxidative purine degradation pathway via allantoin. Activity of the purine-metabolising enzymes observed in other organisms, such as purine nucleoside phosphorylase (EC 2.4.2.1), xanthine phosphoribosyltransferase (EC 2.4.2.22), adenine deaminase (EC 3.5.4.2), adenosine deaminase (EC 3.5.4.4) and guanine deaminase (EC 3.5.4.3), were not detected in potato tuber extracts. These results suggest that the major catabolic pathways of adenine and guanine nucleotides are AMP → IMP → inosine → hypoxanthine → xanthine and GMP → guanosine → xanthosine → xanthine pathways, respectively. Catabolites before xanthosine and xanthine can be utilised in salvage pathways for nucleotide biosynthesis.     

Hormonal requirement for ovum implantation

Hormonal requirement for ovum implantation varies among the species of animals. The methods attempting to clarify the requirement in each species may be classified as follows:

1. (i)
   hormonal replacement therapy after removal of the pituitary or/and the ovaries
    
2. (ii)
   hormonal treatment after reduction of specific hormones by its antiserumin vivo
    
3. (iii)
   close observation of hormone secretion pattern in early pregnancy
    
4. (iv)
   examination of physiological conditions where implantation is delayed and analyze the hormone levels and the receptivity of the target tissues
    
5. (v)
   examination of effects on hormone levels and the receptivity of target tissues of drugs which interfere with implantation. The reported results indicate that both progesterone and estrogen are needed for implantation in rats, mice, and Mongolian gerbils; in other species of animals progesterone alone may be sufficient to induce implantation, although synergistic effect of estrogen appears to be seen in some species such as in the rabbit. It remains to be determined whether the blastocysts of those animals that need only progesterone for implantation have greater ability to produce estrogen than the blastocysts of the animals that need both progesterone and estrogen. Control mechanism of secretion of progesterone and estrogen for inducing implantation may be different in various species. It has been suggested that both leutropin and follicle stimulating hormone are needed for pre-implantation estrogen secretion in the rat, whereas only follicle stimulating hormone is needed in the mouse. In the species where the obligatory delay in implantation is observed, neuroendocrine mechanisms are reported to be involved in controlling the pituitary-ovarian function that causes a delay in implantation.
    

     

Immunocytochemical localization of 17β-hydroxysteroid dehydrogenase in porcine testis

Summary The immunocytochemical localization of 17-hydroxysteroid dehydrogenase (17-HSD) in porcine testes was examined by applying an indirect-immunofluorescence method using an antiporcine testicular 17-HSD antibody. Only the Leydig cells located in the interstitial tissue exhibited a positive immunoreaction for 17-HSD: the germ cells and Sertoli cells located in the seminiferous tubules were entirely negative. These results suggest that, in porcine testis, the biosynthesis of testicular testosterone, the final step of which is the conversion of androstenedione to testosterone, takes place in the Leydig cells.Supported by grants from the Ministry of Education, Science, and Culture, Japan     

25-Hydroxyvitamin D3 loading test in primary hyperparathyroidism, hypoparathyroidism and pseudohypoparathyroidism

Plasma 1,25-dihydroxyvitamin D (1,25-(OH)2D) level, which is considered to be an indicator of parathyroid function, is possibly modified by the level of vitamin D. In the present study, we have investigated parathyroid function in terms of enhancement of the plasma levels of 1,25-(OH)2D after oral administration of 100 micrograms of 25-hydroxyvitamin D3 (25OHD3) in 9 cases of primary hyperparathyroidism (1 degree HPT), 7 cases of hypoparathyroidism (HP), 2 cases of pseudohypoparathyroidism (PHP) and 6 normal subjects. The plasma levels of 25-hydroxyvitamin D (25OHD) increased and reached a peak at 6-12 hours after the administration of 25OHD3. The plasma levels of 1,25-(OH)2D slightly increased but remained within the normal range after 25OHD3 administration in 3 of the normal subjects whose basal levels were rather low, but the increase in plasma 1,25-(OH)2D in control subjects was not statistically significant. In cases of 1 degrees HPT, the plasma 1,25-(OH)2D level rose significantly in all cases (P less than 0.05), although the pattern of the increase was not uniform. These increases were remarkable in the patients whose basal levels were low. On the other hand, an increase in the level was rarely observed in any of the cases of HP and in one of the cases of PHP. In another case, normocalcemic PHP, the plasma 1,25-(OH)2D level rose.(ABSTRACT TRUNCATED AT 250 WORDS)     

Progesterone values in monkeys near term

The serum progesterone of peripheral, ovarian, uterine and umbilical blood from six Macaca mulatta and two M. fascicularis was determined by radioimmunoassay in late pregnancy. Peripheral progesterone values fell to lower levels the day after delivery, a decrease indicating placental progesterone secretion. The concentration of progesterone in the ovarian vein associated with the presence of a corpus luteum was greater than that in the contralateral vein, a difference denoting active progesterone secretion by the corpus luteum. In most cases the uterine vein on the side associated with the placement of the primary and secondary placentae contained more progesterone than its opposite counterpart, a condition that suggests some synthesis of progesterone by the placenta. The umbilical vein/artery progesterone ratio showed fetal metabolism of this steroid and also greater metabolism of progesterone by the female fetus. The progesterone concentration in the ovarian vein associated with the corpus luteum in mothers who bore female fetuses was greater than that of the same vein in those mothers who bore male fetuses. Peripheral progesterone levels were high the day before cesarean section and fell to lower levels the day after delivery. The decline was more rapid in mothers who bore male fetuses.