Immunohistochemical investigation of nerve distribution in mature parotid and submandibular glands of rats with a liquid diet

Background: Although feeding with a liquid diet does not affect the growth of rat submandibular glands, it inhibits the growth of rat parotid glands during growth periods. In these growth-inhibited parotid glands, the growth of parasympathetic nerves is also suppressed. Meanwhile, the mature parotid glands of animals maintained on a liquid diet become morphologically and functionally atrophic, however, there is no effect of a liquid diet on mature submandibular glands. The objective of the present study was to clarify whether the nerve distribution in the mature salivary glands of rats was affected by a liquid diet. Materials and methods: Seven-week-old male Wistar rats were used in this study. Half of the rats were kept on a pellet diet, and half were kept on a liquid diet, for 3, 7, 14, or 21 days. All rats were euthanised by isoflurane at each endpoint. Then, the parotid and submandibular glands were removed, frozen in liquid nitrogen, cryosectioned, and stained with antibodies against protein gene product 9.5 (PGP 9.5; general nerve marker), tyrosine hydroxylase (TH; sympathetic nerve marker), or neuronal nitric oxide synthase (nNOS; parasympathetic nerve marker). Results: In parotid and submandibular glands of the pellet diet group, PGP 9.5- and TH-like immunoreactivity were seen around acini and ducts, and nNOS-like immunoreactivity was lower than PGP 9.5- and TH-like immunoreactivity. In the parotid glands of the liquid diet group, similar immunoreactivities were seen throughout the experimental period. The distribution of antibody labelling in the submandibular glands of the liquid diet group was similar to that of the pellet diet group and remained unchanged during the experimental period. Conclusions: The present study demonstrated no regressive effects of a liquid diet on the distribution of sympathetic or parasympathetic nerves in mature parotid glands and submandibular glands. This differed from inhibitory effects on the growth of parotid glands seen during growth periods

Direct Observation of Site-specific Valence Electronic Structure at Interface: SiO2/Si Interface

Atom specific valence electronic structures at interface are elucidated successfully using soft x-ray absorption and emission spectroscopy. In order to demonstrate the versatility of this method, we investigated SiO2/Si interface as a prototype and directly observed valence electronic states projected at the particular atoms of the SiO2/Si interface; local electronic structure strongly depends on the chemical states of each atom. In addition we compared the experimental results with first-principle calculations, which quantitatively revealed the interfacial properties in atomic-scale.Comment: 4 pages, 3 figure

Cellular function of osteocytes in normal and αklotho-deficient mice

During the last decade, osteocyte-derived factors i.e., sclerostin, dentin matrix protein-1, fibroblast growth factor 23 (FGF23) that reduces serum phosphate concentration by mediating FGF receptor 1c/αklotho in the kidney, have been highlighted for osteocytes’ fine-turned regulation on bone remodeling and phosphate homeostasis. Osteocytes are interconnected through gap junctions between their cytoplasmic processes, and thereby, build upon the functional syncytia, referred to as the osteocytic lacunar-canalicular system (OLCS). Osteocytes appear to communicate surrounding osteocytes and osteoblasts by means of two possible pathways of molecular transport throughout the OLCS : One is a passageway of their cytoplasmic processes, and the other is a pericellular space in the osteocytic canaliculi. The regularly-oriented OLCS in mature compact bone appears to efficiently serve for molecular transport, mechanosensing and targeted bone remodeling that would erase microdamages in bone. In a disrupted signaling state of FGF23/αklotho, serum concentration of phosphate would be markedly-elevated. Despite highly-elevated serum phosphate, αklotho -deficient mice revealed defective mineralization in bone matrix. OLCS in αklotho -deficient mice were irregularly-distributed and the connectivity of cytoplasmic processes of osteocytes was very poor, so that osteocytes did not seem to form functional syncytia. Therefore, osteocytes’function cooperated with other bone cells, rather than serum concentration of calcium/phosphate, and this seems to play a central role in maintaining bone mineralization. In this review, the biological function of the regularly-arranged OLCS in a normal state will be introduced, as well as dysfunctional osteocytes in αklotho-deficient state, using animal models

PHOSPHATEMIC INDEX EVALUATES PHOSPHORUS LOAD

Objective: Dietary phosphorus (P) restriction is crucial to treat hyperphosphatemia and reduce cardiovascular disease risk and mortality in patients with chronic kidney disease (CKD) and the wider population. Various methods for dietary P restriction exist, but the bioavailability of P in food should also be considered when making appropriate food choices to maintain patients’ quality of life. Here, we propose the ‘‘Phosphatemic Index’’ (PI) as a novel tool for evaluating dietary P load based on P bioavailability; we also evaluated the effect of continuous intake of different PI foods in mixed meals on serum intact fibroblast growth factor 23 concentration. Design and Methods: A 2-stage crossover study was conducted: Study 1: 20 healthy participants consumed 10 different foods containing 200 mg of P, and the PI was calculated from the area under the curve of a time versus serum P concentration curve; Study 2: 10 healthy participants consumed 4 different test meals (low, medium, or high PI meals or a control) over a 5-day period. Results: Study 1 showed milk and dairy products had high PI values, pork and ham had medium PI values, and soy and tofu had low PI values. In Study 2, ingestion of high PI test meals showed higher fasting serum intact fibroblast growth factor 23 levels and lower serum 1,25-dihydroxyvitamin D levels compared with ingestion of low PI test meals. Conclusion: These findings suggest that the PI can usefully evaluate the dietary P load of various foods and may help to make appropriate food choices for dietary P restriction in CKD patients

Hertwig's epithelial root sheath cells do not transform into cementoblasts in rat molar cementogenesis

It is generally accepted that cementoblasts originate in the process of differentiation of mesenchymal cells of the dental follicle. Recently, a different hypothesis for the origin of cementoblasts has been proposed. Hertwig's epithelial root sheath cells undergo the epithelial-mesenchymal transformation to differentiate into cementoblasts. To elucidate whether the epithelial-mesenchymal transformation occurs in the epithelial sheath, developing rat molars were examined by keratin-vimentin and Runx2 (runt-related transcription factor 2)-keratin double immunostaining. In both acellular and cellular cementogenesis, epithelial sheath and epithelial cells derived from the epithelial sheath expressed keratin, but did not express vimentin or Runx2. Dental follicle cells and cementoblasts, however, expressed vimentin and Runx2, but did not express keratin. No cells showed coexisting keratin-vimentin or Runx2-keratin staining. These findings suggest that there is no intermediate phenotype transforming epithelial to mesenchymal cells, and that epithelial sheath cells do not generate mineralized tissue. This study concludes that the epithelial-mesenchymal transformation does not occur in Hertwig's epithelial root sheath in rat acellular or cellular cementogenesis and that the dental follicle is the origin of cementoblasts, as has been proposed in the original hypothesis

Three-dimensional reconstruction of the Golgi apparatus in osteoclasts by a combination of NADPase cytochemistry and serial section scanning electron microscopy

The three-dimensional morphology of the Golgi apparatus in osteoclasts was investigated by computer-aided reconstruction. Rat femora were treated for nicotinamide adenine dinucleotide phosphatase (NADPase) cytochemistry, and light microscopy was used to select several osteoclasts in serial semi-thin sections to investigate the Golgi apparatus by backscattered electron-mode scanning electron microscopy. Lace-like structures with strong backscattered electron signals were observed around the nuclei. These structures, observed within the Golgi apparatus, were attributed to the reaction products (i.e., lead precipitates) of NADPase cytochemistry. Features on the images corresponding to the Golgi apparatus, nuclei, and ruffled border were manually traced and three-dimensionally reconstructed using ImageJ/Fiji (an open-source image processing package). In the reconstructed model, the Golgi apparatus formed an almost-continuous structure with a basket-like configuration, which surrounded all the nuclei and also partitioned them. This peculiar three-dimensional morphology of the Golgi apparatus was discovered for the first time in this study. On the basis of the location of the cis- and trans-sides of the Golgi apparatus and the reported results of previous studies, we postulated that the nuclear membrane synthesized specific proteins in the osteoclasts and, accordingly, the Golgi apparatus accumulated around the nuclei as a receptacle