Biomedical subjects
A Ishihara
Publications and source records attributed to A Ishihara.
NPY-induced feeding involves the action of a Y1-like receptor in rodents.
We have reported that the potent peptidic Y1 antagonist, 1229U91, significantly suppressed NPY-induced and spontaneous feeding [32,33]. However, information on the precise selectivity of 1229U91 for NPY receptors is lacking. The Y5 receptor has been considered a key receptor for feeding regulation. In the present study we showed that 1229U91 has high affinities for the human and rat Y1 receptors (Ki = 0.041 nM and 0.16 nM, respectively) and also a high affinity for the human Y4 receptor (Ki = 0.33 nM), whereas it shows moderate affinities for the human Y2, Y5 and rat Y5 receptors (K values of 20-170 nM). Moreover, 1229U91 potently inhibits NPY-induced [Ca2+]i increases in cells expressing human Y1 receptors. In contrast, 1229U91 is an agonist at other NPY receptors like the Y2, Y4 and Y5 receptors. Intracerebroventricular (i.c.v.)-injected 1229U91 (30 microg/head) significantly suppressed human NPY-induced feeding in SD rats, while 1229U91 only moderately inhibited bovine pancreatic polypeptide (bPP; an in vivo Y5 agonist)-induced feeding. These results indicate that the food intake evoked by NPY might be mediated by the Y1 receptor, rather than the Y5 receptor. Thus, the Y1 receptor or possibly a novel Y1-like receptor sensitive to 1229U91 may play a key role in the regulation of NPY-induced feeding.
Hindlimb suspension induces the expression of multiple myosin heavy chain isoforms in single fibres of the rat soleus muscle.
To examine the expression patterns of myosin heavy chain (MHC) isoforms in single fibres of the soleus muscle following weightlessness, 10-week-old male Wistar rats were subjected to hindlimb suspension for 4 weeks. Hindlimb suspension resulted in reduced body weight and absolute and relative mass of the soleus muscle compared with controls (P < 0.01). A total of 975, 892 and 1098 single fibres from pre-suspended controls, age-matched controls and suspension groups, respectively, were subjected to MHC analyses using SDS-PAGE. Single fibres containing only MHC I decreased (87.9 vs. 67.9%, P < 0.05) and single fibres containing only MHC IIa disappeared after hindlimb suspension. On the contrary, single fibres containing multiple type II MHC isoforms were observed as follows: 10.1% single fibres contained MHCs IIa and IId; 14.1% contained MHCs I, IIa and IId; and some (1.4%) expressed the MHC IIb isoform with MHCs IIa and IId. The relative content (%) of each MHC isoform in MHC hybrid single fibres was calculated using densitometer scanning. The MHCs IIa and IId hybrid single fibres contained the same amount of MHC IIa (51.3 +/- 6.3%) and MHC IId (48.7 +/- 6.3%). In the MHCs I, IIa and IId hybrid single fibres, the percentage of MHC IIa was distributed in a wide range (approximately 80%), whereas the percentage of MHC IId was a relatively low range (approximately 40%), and the relative content of MHC I was inversely correlated with that of MHC IIa and MHC IId, respectively. The fibre type composition of suspended soleus muscle, analysed by histochemical myosin ATPase staining, was changed, with a decrease in the percentage of type I fibres and an increase in that of type IIA fibres. Our results indicate that hindlimb suspension induces multiple type II MHC expression in the soleus single fibres and suggest that the single fibres containing multiple type II MHC isoforms should be classified into type IIA.
Bone wound healing after maxillary molar extraction in ovariectomized aged rats.
We studied bone wound healing processes after maxillary molar extraction in ovariectomized (OVX) aged rats, as an experimental model of postmenopausal osteoporosis, by means of scanning electron microscopy. Six-month-old female rats were either sham-operated or bilaterally OVX; and at 60 days postoperatively, the maxillary first molars were extracted. On postextraction days 4, 7, 30 and 60, the dissected maxillae were fixed and the alveolar bone surfaces around the extracted alveolar sockets were examined. In sham-operated controls, new bone formation was recognized on the buccal-side bone surfaces on day 4 and then increased in extent daily through day 60 mainly on the buccal and mesial sides. On day 60, the extracted sockets were filled with new bone mass and the surrounding alveolar bone surfaces had become smooth, indicating decreased bone metabolism. Bone resorption was prominent throughout the bone surfaces around and within the extracted sockets, increased in extent through day 7, but had decreased by day 60. In comparison to sham-operated controls, new bone formation in OVX rats was slightly increased in the early phase but subsequently showed a marked decrease. Bone resorption in OVX rats was greatly stimulated and was comparatively long-lasting. These results suggest that, under the present experimental conditions, in bone wound healing after maxillary molar extraction, (i) ovariectomy stimulates sustained bone resorption and (ii) bone formation and resorption both take place at specific sites on alveolar bone surfaces.
Extrauterine low-grade endometrial stromal sarcoma: report of three cases.
Three cases of rare low-grade endometrial stromal sarcoma of the extrauterine tissue are presented. Each one occurred in the ovary, pelvic and abdominal cavities. Two were associated with endometriosis. Histologically, the tumors were characterized by an infiltrative and diffuse proliferation of uniform round or oval cells, abundant small vessels, low mitotic activity, the presence of foam cells and vascular invasion. Immunohistochemically, all tumors expressed vimentin, muscle markers (desmin, muscle-specific actin and alpha-smooth muscle actin) and progesterone receptors. Two tumors were diploid and one was aneuploid by flow cytometry. All patients were well with no evidence of disease 16-39 months after surgery. It is suggested that this neoplasm may arise with or without endometriosis under hormonal influence. This rare variant of Müllerian tumors should not be confused with adenosarcoma and soft tissue tumors, such as smooth muscle tumors and solitary fibrous tumor.
A potent neuropeptide Y antagonist, 1229U91, suppressed spontaneous food intake in Zucker fatty rats.
Neuropeptide Y (NPY) is one of the most potent orexigenic substances known. 1229U91 was found to be a potent and selective NPY antagonist. To elucidate a physiological role of NPY in hyperphagia in obese animals, we studied the effect of 1229U91 on spontaneous food intake in obese and lean Zucker rats. The food intake of Zucker rats was suppressed by intracerebroventricular administration of 1229U91 more potently in obese than in lean animals without abnormal behavior (31.7 and 67.3% inhibition at doses of 10 and 30 micrograms, respectively, in Zucker fatty rats and 22.2% inhibition at 30 micrograms in lean rats). This compound markedly suppressed NPY-induced food intake at 30 micrograms but did not affect galanin-induced food intake, suggesting that the feeding suppression seen in Zucker fatty and lean rats is pharmacologically and behaviorally specific. These results suggest that NPY is involved in feeding behavior in Zucker fatty rats and that NPY contributes to feeding to a greater degree in Zucker fatty than in lean rats. The hyperphagia in Zucker fatty rats may be due to the abnormal overactivation of the NPYergic system.
Hypertrophy of rat plantaris muscle fibers after voluntary running with increasing loads.
There have been no systematic comparisons of skeletal muscle adaptations in response to voluntary wheel running under controlled loading conditions. To accomplish this, a voluntary running wheel for rats and mice was developed in which a known load can be controlled and monitored electronically. Five-week-old male Sprague-Dawley rats (10 rats/group) were assigned randomly to either a 1) sedentary control group (Control); 2) voluntary exercised with no load (Run-No-Load) group; or 3) voluntary exercised with additional load (Run-Load) group for 8 wk. The load for the Run-Load group was progressively increased to reach approximately 60% of body weight during the last week of training. The proportions of fast glycolytic (FG), fast oxidative glycolytic (FOG), or slow oxidative (SO) fibers in the plantaris were similar in all groups. The absolute and relative plantaris weights were greater in the Run-Load group compared with the Control and Run-No-Load groups. The mean fiber cross-sectional areas of FG, FOG, and SO fibers were 20, 25, and 15% greater in the Run-Load than in Control rats. In addition, these fiber types were 16, 21, and 12% larger in Run-Load than in Run-No-Load rats. The muscle weights and mean cross-sectional areas of each fiber type were highly correlated with the average running distances and total work performed in the Run-Load, but not the Run-No-Load, group. The slope of the relationship between fiber size and running distance and total work performed was significant for each fiber type but was higher for FG and FOG fibers compared with SO fibers. These data show that the load on a rat running voluntarily can determine the magnitude of a hypertrophic response and the population of motor units that are recruited to perform at a given loading condition.
Formation of hydroxyfuranone and hydroxypyranone derivatives with DNA-breaking activity in the Maillard reaction of glucose and albumin under physiological conditions.
Formation of DNA breaking hydroxyfuranone and hydroxypyranone derivatives in the Maillard reaction of glucose and bovine serum albumin (BSA) under physiological conditions was investigated. A mixture of glucose and BSA was incubated at 37 degrees C in water or in 1 M phosphate buffer (pH 7.4). The ethyl acetate/2-propanol extract of the reaction mixtures showed significant DNA breaking activity against supercoiled DNA especially in the presence of Fe(III) ion. Gas chromatography/mass spectrometry analysis of the mixture revealed the formation of DNA breaking hydroxyfuranones (HMF and DMHF) and hydroxypyranone (DDMP).
[Clinical evaluation of fundic gland polyps and hyperplastic polyps].
We performed a retrospective review of 477 cases of fundic gland polyps compared with 562 cases of hyperplastic polyps, which were detected endoscopically during the past 8 years between January, 1989 and December, 1996. All lesions were histologically confirmed by endoscopic biopsy or the examination of polypectomy specimens. Fundic gland polyps were more prevalent in middle aged-female, and were not associated with gastric adenomas and gastric cancers. These results suggested that the background mucosa of patients with fundic gland polyp was different from that of patients with hyperplastic polyp. Fundic gland polyps in 55 patients were followed up. No change was observed in the polyps of the about half subjects, the polyps of 12 cases (21.8%) decreased in size and number or resolved completely. Cases decreased in size and number or resolved completely were much more in fundic gland polyps than hyperplastic polyps. There were no malignant transformation of fundic gland polyps. We claimed that fundic gland polyps were benign and distinct from hyperplastic polyps which had a possibility of malignant transformation.
Co-expression of tenascin and fibronectin in epithelial and stromal cells of benign lesions and ductal carcinomas in the human breast.
Tenascin (TN)-C and fibronectin (FN), which are glycoproteins of the extracellular matrix (ECM), are up-regulated in cancer tissues, including breast cancer. For assessment of their involvement in cancer invasion, it is important to know which cells are responsible for their production and secretion. The distribution of cells expressing TN and FN mRNAs in benign and malignant human breast tissues was therefore analysed by in situ hybridization, using digoxigenin-labelled cRNA probes, in addition to demonstrating the proteins immunohistochemically. Both mRNAs were expressed in epithelial cancer as well as in stromal cells in a large fraction of the tumours, with co-expression in individual cells. In cancers with intraductal components and/or those consisting of large nests, the mRNAs were more often expressed in the cancer than in the stromal cells. In scirrhous carcinomas, in contrast, the stromal cells were almost always positive for TN and FN mRNAs, while the cancer cells only rarely exhibited TN or FN expression. In benign lesions including adenosis, fibroadenoma and intraductal papilloma, the expression patterns also varied. These findings indicate that TN and FN co-expressed by cancer cells and stromal cells are probably involved in the intraductal extension and early invasion of cancer cells and in the remodelling of cancer stroma.
Effects of 14 days of spaceflight and nine days of recovery on cell body size and succinate dehydrogenase activity of rat dorsal root ganglion neurons.
The cross-sectional areas and succinate dehydrogenase activities of L5 dorsal root ganglion neurons in rats were determined after 14 days of spaceflight and after nine days of recovery. The mean and distribution of the cross-sectional areas were similar to age-matched, ground-based controls for both the spaceflight and for the spaceflight plus recovery groups. The mean succinate dehydrogenase activity was significantly lower in spaceflight compared to aged-matched control rats, whereas the mean succinate dehydrogenase activity was similar in age-matched control and spaceflight plus recovery rats. The mean succinate dehydrogenase activity of neurons with cross-sectional areas between 1000 and 2000 microns2 was lower (between 7 and 10%) in both the spaceflight and the spaceflight plus recovery groups compared to the appropriate control groups. The reduction in the oxidative capacity of a subpopulation of sensory neurons having relatively large cross-sectional areas immediately following spaceflight and the sustained depression for nine days after returning to 1 g suggest that the 0 g environment induced significant alterations in proprioceptive function.
Modulation of MHC isoforms in functionally overloaded and exercised rat plantaris fibers.
The effects of 1 and 10 wk of functional overload (FO) of the rat plantaris with (FOTr) and without daily endurance treadmill training on its myosin heavy chain (MHC) composition were studied. After 1 and 10 wk of FO, plantaris mass was 22 and 56% greater in FO and 37 and 94% greater, respectively, in FOTr rats compared with age-matched controls. At 1 wk, pure type I and pure type IIa MHC fibers were hypertrophied in FO (39 and 44%) and FOTr (70 and 87%) rats. By 10 wk all fiber types comprising >5% of the fibers sampled showed a hypertrophic response in both FO groups. One week of FO increased the percentage of hybrid (containing both type I and type IIa MHC) fibers and of fibers containing embryonic MHC. By 10 wk, the percentage of pure type I MHC fibers was approximately 40% in both FO groups compared with 15% in controls, and the percentage of fibers containing embryonic MHC was similar to that in controls. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses showed an increase in type I MHC and a decrease in type IIb MHC in both FO groups at 10 wk, whereas little change was observed at 1 wk. These data are consistent with hypertrophy and transformation from faster to slower MHC isoforms in chronically overloaded muscles. The additional overload imposed by daily endurance treadmill training employed in this study (1.6 km/day; 10% incline) results in a larger hypertrophic response but appears to have a minimal effect on the MHC adaptations.
Overview: functional implications of the design of skeletal muscles.
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Perineal muscles and their innervation: metabolic and functional significance of the motor unit.
Cross-sectional areas and succinate dehydrogenase (SDH) activities of muscle fibers in the rat levator ani (LA) and bulbocavernosus (BC) were determined and compared with those of the soleus (SOL) and superficial (TAs) and deep (TAd) portions of the tibialis anterior (TA). In addition, cell body sizes and SDH activities of spinal motoneurons innervating the LA and BC were examined. Histochemical myofibrillar adenosine triphosphatase (mATPase) staining reactions following alkaline and acid preincubations revealed that all the muscle fibers in the LA and BC were type IIB. Gel electrophoresis, however, showed that the LA and BC contained 2.9 and 2.4% type IIx myosin heavy chain (MHC) isoform, respectively. Immunohistochemical analyses using MHC antibodies showed that the muscle fibers in the LA and BC had types IIx / IIa (approximately 3%) or type IIb MHC isoforms. The mean fiber cross-sectional areas in the LA and BC were significantly smaller than those in the SOL, TAs, or TAd. The mean fiber SDH activities in the LA and BC were significantly lower than those in the SOL or TAd, and similar to TAs. The population of alpha motoneurons innervating the LA and BC had similar SDH activities, irrespective of their cell body sizes. These data indicate that the LA and BC are comprised of a relatively homogeneous population of small, fast and low oxidative fibers innervated by a relatively homogeneous population of spinal motoneurons. These characteristics of the muscle fibers and motoneurons are consistent with their function in short, high-intensity activities.
Mitochondrial density of ventral horn neurons in the rat spinal cord.
Mitochondrial density in neurons of the dorsolateral region of the ventral horn at the L5 spinal cord segment in rats was examined using electron microscopy. The gamma motoneurons had a higher density of mitochondria (25.1 +/- 4.2%, n = 19) in the cytoplasm compared to the alpha motoneurons which had a mitochondrial density of 19.4 +/- 4.5% (n = 38). An inverse relationship between cell body size and mitochondrial density was found for alpha (n = 38) and alpha plus gamma (n = 57), but not for gamma (n = 19), motoneuron populations. The higher densities of mitochondria in the smaller neurons correspond well with their metabolic properties since the smaller neurons have the highest oxidative enzyme activities.
Photoactivation of caged compounds in single living cells: an application to the study of cell locomotion.
Caged compounds are molecules whose biological function is masked until UV light induces a photo-chemical reaction that converts the molecules into a biologically active state. These probes provide very powerful tools in cell biology research, since the activation can be precisely controlled temporally and spatially by limiting their exposure to light. This report describes a simple caged compound illuminator that can be attached to an inverted microscope; it can simultaneously provide both sufficient UV illumination for photoactivation and epifluorescence excitation to monitor indicator fluorescence. As an example, we show that the cytoplasmic calcium level can be raised very rapidly by the photoactivation of a new caged compound, caged calcium ionophore DMNPE-A23187, and that this [Ca2+]i increase is associated with tail retraction of motile keratocytes.
Influence of two weeks of non-weight bearing on rat soleus motoneurons and muscle fibers.
BACKGROUND: Chronic unloading of the hindlimbs of rats results in atrophy and a shift in the metabolic and mechanical properties of the soleus muscle a predominantly slow postural muscle, towards those observed in faster muscles. HYPOTHESIS: We hypothesized that the spinal motoneurons innervating the soleus muscle would also atrophy and show adaptations in their metabolic properties following a period of unloading. METHODS: For 2 weeks, 10-week-old male Wistar rats were hindlimb suspended and the mean soma size and succinate dehydrogenase activity of motoneurons innervating the soleus muscle were examined. Retrograde labeling with nuclear yellow injected in the soleus muscle was used to identify the soleus motor pool. The mean fiber size and fiber type distribution from a central region of each soleus muscle was determined. RESULTS: The soma size distribution, mean soma cross-sectional area and mean succinate dehydrogenase activity of motoneurons in the soleus motor pool were similar in control and hindlimb suspended rats. In contrast, compared to control the mean fiber size of each fiber type and the percentages of Type I fibers decreased and of Type IIa fibers increased in the soleus muscle following hindlimb suspension. CONCLUSIONS: The results indicate that significant alterations in the phenotype and size of muscle fibers can occur without concomitant adaptations in the innervating motoneurons usually associated with motor unit types (i.e., soma size and oxidative capacity).
Transforming growth factor-beta 1 promotes re-elongation of injured axons of cultured rat hippocampal neurons.
Transforming growth factor-beta 1 (TGF-beta 1) is highly expressed in neural tissues following brain injuries. To determine a role of TGF-beta 1 in neural pathologies, axons of cultured rat hippocampal neurons were cut by local irradiation of laser beam, and the effect of TGF-beta 1 on neurite regeneration following axotomy was investigated. The axonal growth was stopped by laser irradiation, but addition of TGF-beta 1 remarkably promoted the axonal re-elongation from the injured site. The effect of TGF-beta 1 was concentration dependent and seen maximally at a concentration of 1 ng/ml. These results suggest that TGF-beta 1 has a capability of promoting axonal regeneration of brain neurons after lesioning.