Iron lactate-induced osteopenia in male Sprague-Dawley rats

Osteopenia was induced in rats fed a diet containing 50,000 ppm (5%) iron lactate for 2 or 4 weeks. Blood chemistry, urinalysis, and bone histomorphometry of the proximal tibial metaphysis were performed. Urinary pyridinoline and deoxypyridinoline and the osteoclast number per bone surface were selected for the measurement of dynamic resorption. The osteoclast surface, eroded surface, and osteoblast surface increased at both ends of the exposure periods, and bone resorption and formation both increased. The bone volume, trabecular thickness, and trabecular number decreased, and the secondary spongiosa of proximal metaphysis showed a marked bone loss. However, no mineralization defect was observed. At the end of the 2-week exposure period, biomarkers of osteoclasts and osteoblasts had increased the most, and the osteoblast surface, osteoclast surface, and osteoclast number per bone surface increased with prolonged exposure. The pathological changes of the bone lesion in iron lactate-overloaded rats were similar to those in rats of the osteoporotic model, because they consisted of changes reflecting the increase of bone resorption and formation without an osteomalacic change. However, the decline of serum parathyroid hormone (PTH) levels was different from that of the osteoporosis model rat. We concluded iron-induced bone lesions probably differ from those of low turnover bone diseases.

[A pediatric case of intractable complex partial seizures associated with mesial temporal lobe astrocytoma: usefulness of interictal epileptiform discharges in the present case]

The patient was a 10-year-old male with normal developmental milestones. He had medically intractable complex partial seizures since the age of 7 years. At the age of 10 years, he had focal motor seizures of the right face, and a head CT scan showed a calcified lesion in the left mesial temporal region. The tumor exhibited low intensity on T 1-weighted and high intensity on T 2-weighted MR images, and was not enhanced by gadolinium-diethylenetriamine pentaacetic acid. Interictal SPECT showed hypoperfusion in the left temporal region. One-day video/EEG monitoring revealed very frequent epileptiform discharges which occurred only during sleep period exclusively in the left anterior-to-middle temporal region. The patient underwent lesionectomy with the guidance of electrocorticography. The histological study of the resected tissue showed astrocytoma. After surgery he has had no seizures for 10 months. It was concluded that very frequent interictal epileptiform discharges strictly localized to the temporal lobe at which MRI-identified tumor was present could be predictive of epileptogenic zone in the present patient in whom clinical symptoms and the results of other studies were also concordant.

Basic studies on the equivalent cross-relaxation rate imaging (equivalent CRI)--phantom studies

We have studied saturation transfer in hydrophilic, cross-linked copolymer gels from irradiated polymer protons to observed water protons, using f2 (ppm) profiles of [1 - (I(infinity)/I(0))], [(I(0)/I(infinity)) - 1] or 1/T(IS)(H2O), where I(0) and I(infinity) are the longitudinal magnetization of the observed water protons before and after long-time-f2-irradiation on polymer protons, respectively, and 1/T(IS)(H2O) is the cross-relaxation rate. (A) [1 - (I(infinity)/I(0))] (magnetization transfer ratio, MTR) was used in magnetic resonance imaging (MRI) as the MTR imaging. 1/T(IS)(H2O) (cross-relaxation rate) was used in the imaging of the magnetization transfer rate constant. This method was quite time-consuming compared with MTR imaging. However, f2 (ppm) profiles of [(I(0)/I(infinity)) - 1] correlated well with corresponding profiles of 1/T(IS)(H2O), because [(I(0)/I(infinity)) - 1] is equal to 1/[T(IS)(H2O)/T1(H2O)]. These results lead us to the conclusion that [(I(0)/I(infinity)) - 1] might be applicable to cross-relaxation rate (CR)-like imaging, i.e. equivalent CRI. (B) W (%) (dry weight) profiles of [(I(0)/I(infinity)) - 1] and 1/T(IS)(H2O), obtained by near-resonance f2-irradiation, seem to indicate participation of molecular rigidity and an amount of bound water. However, those values, monitored with off-resonance f2-irradiation, seem to be independent of monomer composition and to indicate mainly participation of rigidity, i.e. W (%) of copolymer gels.

Mechanism of protection by S-(1,2-dicarboxyethyl)glutathione triester against acetaminophen-induced hepatotoxicity in rat hepatocytes

Treatment with the triester of S-(1,2-dicarboxyethyl)glutathione (DCE-GS) prevented the hepatotoxicity induced by acetaminophen via elevation of the glutathione (GSH) level in rat hepatocytes. This elevation of the GSH level in rat hepatocytes by DCE-GS triester was dose- and time-dependent (2.1-fold in 24 h with 0.5 mm). DCE-GS triester increased the GSH level much more effectively than GSH, DCE-GS, and DCE-GS monoester and diester. Furthermore, the activity of y-glutamylcysteine synthetase (gamma-GCS), the rate-limiting enzyme in GSH biosynthesis, was also increased by DCE-GS triester treatment (1.4-fold in 24 h with 1.0 mm). In contrast, with a rat liver homogenate, DCE-GS increased the y-GCS activity, whereas DCE-GS triester had no effect on this activity. These results suggested that DCE-GS triester, which is transported into hepatocytes much more effectively than DCE-GS and other DCE-GS esters due to its greater lipophilicity, was hydrolyzed to DCE-GS, and then the DCE-GS produced increased the GSH level via activation of gamma-GCS in rat hepatocytes.

Effects of photoperiod and melatonin on the development of growth hormone cells and the pituitary-adrenal axis in the Djungarian hamster, Phodopus sungorus

The development of GH cells and the pituitary-adrenal axis was morphologically examined in male Djungarian hamsters (Phodopus sungorus) exposed to short days and those kept under long days and receiving daily afternoon injections of melatonin, from the time of weaning (20 days) until 100 days of age. The postnatal increase in area of ACTH cells under long days was inhibited in short-day-exposed or melatonin-treated animals. It was suggested that a short photoperiod may suppress, via melatonin, the development of ACTH cells. GH cells were not affected by age, photoperiod or exogenous melatonin. Under long days, the zona fasciculata decreased in volume with age, while the zona reticularis increased. Such changes in the volumes of these adrenocortical zones were depressed under short days. In addition, the volumes of the zona fasciculata and zona reticularis in long-day-housed animals became respectively larger and smaller subsequent to orchidectomy and melatonin administration. These results suggest that fasciculata cells in deeper levels become progressively differentiated into reticularis cells, that short photoperiod inhibits development of both zonae, and that such an inhibition is caused mainly by the decreased secretion of androgens.

Evaluation of the prognostic factors after thymoma resection

We discuss the prognostic factors of thymoma clinicopathologically. Regarding the survival rate by the clinical stage classification of Masaoka, significant correlation was made between stage I and stage III (P < 0.05) and stage I and stage IVa (P < 0.03). The tumor resectability was classified into complete and incomplete resection, and a significant difference was shown by the survival rate of the complete resection at P < 0.0001. Regarding the survival rate by the invasive organ of the tumor, significant correlation was made between no invasion and the great vessel invasion (P < 0.0004) and between invasion except for the great vessel and great vessel invasion (P < 0.004). As for the histological type, the tendency in which the epithelial cell type predominancy increased with the progress of the clinical stage was shown. A significant correlation was not shown in the evaluation by adjuvant therapy. However, recently we have done chemotherapy and/or radiotherapy periodically for invasive thymoma.

Central GABAergic innervation of the mammalian pineal gland: a light and electron microscopic immunocytochemical investigation in rodent and nonrodent species

Light and electron microscopic immunocytochemical observations were made to demonstrate central pinealopetal fibers immunoreactive for gamma-aminobutyric acid (GABA) and synapses between their terminals and pinealocytes in the pineal gland of four rodent (Wistar-King rat; mouse; Syrian hamster, Mesocricetus auratus; Hartley strain guinea pig) and one nonrodent (tree shrew, Tupaia glis) species. GABA-immunoreactive myelinated and unmyelinated fibers and endings were found in the parenchyma of the pineal gland of all the animals examined. In the rodent species, GABAergic fibers were mainly found in the intermediate and proximal portions of the pineal gland and were nearly or entirely absent in the distal portion of the gland. Abundant GABAergic fibers were evenly distributed throughout the gland of the tree shrew. In all the animals, the habenular and posterior commissures contained abundant GABA-positive fibers, and some of them were followed to the pineal gland. GABA-positive endings made synaptic contact with pinealocytes, occasionally in mice and guinea pigs, and frequently in tree shrews; no synapses were observed in Syrian hamsters and rats. In the pineal gland of all the animals, GABA-immunoreactive cell bodies were not detected, and sympathetic fibers were not immunoreactive for GABA. These data indicate that GABAergic fibers are main pinealopetal projections from the brain. In view of the difference in the distribution of these fibers, central GABAergic innervation may play a more significant role in nonrodents than in rodents. The frequent occurrence of GABAergic synapses on pinealocytes in the tree shrew suggests that GABA released at these synapses directly controls activity of pinealocytes of this animal.

Localization of cellubrevin-related peptide, endobrevin, in the early endosome in pancreatic beta cells and its physiological function in exo-endocytosis of secretory granules

Cellubrevins are integral membrane proteins expressed in a wide variety of tissues and usually localized in recycling vesicles. Here, we investigated the cellular localization of a cellubrevin-related peptide, endobrevin, in pancreatic (beta) cells and its implication in the exo-endocytosis of insulin and (gamma)-amino butyric acid (GABA). Immunocytochemistry showed that endobrevin is associated with tubulo-vesicular structures, which are colocalized with early endosomes labeled by early endosome antigen (EEA)-1 in insulinoma MIN6 cells. To determine the cellular localization of endobrevin, we appended the green fluorescent protein (GFP) to endobrevin and the fusion protein was introduced into MIN6 cells. The subcellular localization of GFP-endobrevin was visualized by confocal laser microscopy. Colocalization study based on the expressed GFP-endobrevin and endocytosed Texas-Red(Tx-R) labeled transferrin receptor and immunocytochemistry with anti-EEA1 antibody revealed that endobrevin was preferentially localized in the early endosome. Then, we examined the functional role of endobrevin in the exocytosis of insulin and GABA from pancreatic (beta) cells. Endobrevin overexpression increased the amount of GABA released from MIN6 cells; in contrast, it decreased the glucose-stimulated insulin release from rat islets, MIN6 and INS1-D cells to approximately 50% of the control levels. Both in vitro and in vivo binding studies showed that endobrevin binds to syntaxin 1. Finally, using the fluorescent probe FM4-64, it was revealed that endobrevin overexpression accelerates vesicle recycling. We conclude that (1) endobrevin is localized in the early endosome in pancreatic (beta) cells and (2) endobrevin plays a physiological role in the exo-endocytosis of insulin and GABA from pancreatic (beta) cells, probably via an interaction between endocytic vesicles and the endosome.

The increase of memory T cell subsets in children with idiopathic nephrotic syndrome

Two-color and three-color flow cytometry was carried out to determine whether the memory T cells (CD45RO+ T cells) play a major role in lymphocyte dysfunction of 26 children with idiopathic nephrotic syndrome (INS). The INS patients were divided into three groups: (1) 10 patients who were not receiving glucocorticoid hormone (GCH) and were suffering from acute nephrotic state were referred to as N1; (2) 8 patients who were in remission maintained by GCH therapy alone were referred to as N2; (3) 8 patients who were free of GCH therapy for at least 4 months were referred to as N3. Group N1 demonstrated a significant increase in the percentage of CD45RO+CD4+ T cells and CD45RO+CD8+ T cells (p < 0.05) compared with 11 controls, and these subsets were noted to have a tendency to decrease to control levels in groups N2 and N3. Furthermore, interleukin-2 receptor-alpha expressed subsets in CD45RO+CD4+ T cells (CD45RO+CD4+CD25+ T cells) were also increased only in group N1 (p < 0.02). A similar tendency of absolute counts was observed in these subsets. These results suggest that activated memory T cells reflect lymphocyte dysfunction at initial onset or relapse in INS children.

Separation and assay methods for melatonin and its precursors

Melatonin is an indoleamine hormone that is synthesized from tryptophan via 5-hydroxytryptophan, serotonin and N-acetylserotonin in the vertebrate pineal gland. Many chromatographic and non-chromatographic techniques have been developed and improved for the determination and measurement of melatonin and its related indoleamines. At present, gas chromatography with mass spectrometry and reversed-phase high-performance liquid chromatography with fluorescence or electrochemical detection are widely used for indoleamine determinations in the pineal gland. This review will deal with methods for the separation and determination of the melatonin and its related indoleamines.

S-(1,2-dicarboxyethyl)glutatidone esters elevate glutatidone level in human hepatoma hepg2 cell

Abstract:

The elevating effect of S-(1,2-dicarboxyethyl)glutathione (DCE-GS) esters on the glutathione (GSH) content was examined using human hepatocellular carcinoma cell line HepG2. The treatment with DCE-GS diester and triester (0.5 mM) increased the GSH level in HepG2 cells up to 145 and 175% over control level after 24h, respectively. DCE-GS diester and triester also elevated y-glutamylcysteine synthetase (y-GCS) activity in HepG2 cells up to 125 and 150% over the control level after 24h, respectively. However, this elevation of y-GCS did not occur on treatment with bis-(p-nitrophenyl)phosphate, non-specific esterase inhibitor. It is therefore concluded that DCE-GS diester and triester are transported into cells and hydrolyzed intracellularly to DCE-GS, and then DCE-GS produced promotes GSH synthesis due to the activation of y-GCS.

Saturation transfer ratio imaging in invasive ductal carcinomas of the breast

A prospective study was performed to investigate the correlations between saturation transfer ratio (STR) and histologic parameters of invasive ductal carcinomas in human breast. The histologic parameters investigated were the extent of fibrosis in the intercellular matrix, dysplastic changes of nuclei, and mitotic index. Twenty-seven patients with breast carcinoma were examined using an off-resonance saturation pulse in conjunction with conventional field-echo T(1)-weighted imaging at frequency offsets of 448 Hz and 1200 Hz from water resonance. The values of STR at frequency offset of 1200 Hz (STR(1200)) increased from non-scirrhous carcinoma to scirrhous carcinoma. Although STR(1200) showed correlation with the extent of fibrosis in the intercellular matrix (p<0.01, n = 27), they did not correlate with the dysplastic changes of nuclei or mitotic index. On the other hand, the values of STR at frequency offset of 448 Hz (STR(448)) demonstrated close correlation to dysplastic changes of nuclei and mitotic index (p<0.01, n = 27). STR(1200) correlates with the structural characteristics and STR(448) correlates with the nature of malignant cells with regard to nuclear dysplasia and mitotic potential.

Evaluation of prognostic factors and PCNA expression for pulmonary metastatic tumors of colorectal carcinoma

The present study was conducted to evaluate clinicopathologically 26 patients whose primary colorectal carcinoma and resulting pulmonary metastatic tumors had been resected, and to determine the relationship between tumor progress and prognosis by PCNA immunostaining. Patients with solitary pulmonary metastasis were found to have much better prognoses than those with multiple metastasis. There was no correlation between tumor size of pulmonary metastasis and prognosis. Survival rates of patients with disease-free intervals (DFIs) of 2 years or longer were higher than for those with DFIs of less than 2 years. Mean PCNA expression of pulmonary metastatic lesions was significantly higher than that of primary lesions. It was suggested that the higher PCNA expression stemming from the relation between depth of tumor invasion and PCNA expression was greater with tumor progress.

Decreased expression of t-SNARE, syntaxin 1, and SNAP-25 in pancreatic beta-cells is involved in impaired insulin secretion from diabetic GK rat islets: restoration of decreased t-SNARE proteins improves impaired insulin secretion

The physiological role of soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor (SNARE) proteins in insulin exocytosis has been reported in pancreatic beta-cells. To determine whether the beta-cells of GK rats, a nonobese rodent model of type 2 diabetes, exhibit abnormalities in their SNARE proteins, we studied the expression and function of target (t)-SNAREs, syntaxin 1A, and synaptosomal-associated protein of 25 kDa (SNAP-25) in GK rat islets. Although insulin release and insulin content of islets isolated from 12-week-old GK rats were reduced, the proinsulin biosynthetic rate was about twofold higher than that in control rat islets, and no change in the preproinsulin mRNA level was observed. Pulse-chase experiments suggested the increased degradation of insulin in GK rat islets. Immunoblot analysis revealed that protein levels of syntaxin 1A and SNAP-25 in GK rat islets decreased to approximately 60% of the levels in control rat islets. We then examined whether the restoration of the decreased expression of t-SNAREs to the normal level in GK rat islets affected insulin secretion. Restoration was achieved by the overexpression of syntaxin 1A and SNAP-25 via the recombinant adenovirus-mediated gene transduction system, which recovered levels of these proteins to almost control levels. Glucose-stimulated insulin release from AdexlCA syntaxin 1A and Adex1CA SNAP-25-infected GK rat islets increased up to approximately 135 and 200%, respectively, of those from uninfected GK rat islets, although no difference in basal (2.2 mmol/l glucose) insulin release was evident between them. We conclude that decreased expression of t-SNAREs in GK rat islets is in part the defect responsible for impaired insulin secretion.

Decrease in the prevalence of IL-4-producing CD4+ T cells in patients with advanced stage of primary biliary cirrhosis

OBJECTIVE

To elucidate the precise immunological features in primary biliary cirrhosis (PBC), we examined the relative prevalence of CD4+ T cells in either symptomatic PBC (sPBC) or asymptomatic PBC patients (aPBC), and furthermore, these results were compared with their histological features.

METHODS

Cytokine synthesis of peripheral blood mononuclear cells obtained from 24 PBC patients (9 sPBC and 15 aPBC) were examined by intracellular staining method. The relative prevalence of three distinct CD4+ T cells, gamma-interferon (IFN-gamma)-producing cells (Th1), interleukin-4 (IL-4)-producing cells (Th2), and the cells producing both IL-4 and IFN-gamma (Th0), was analyzed by FACScan and compared with those of closely age-matched healthy and disease controls.

RESULTS

The results demonstrated that although a significant difference was not observed in the prevalence of Th1 or Th0, a remarkable difference was observed in the prevalence of Th2 (1.2+/-0.7 in sPBC, 4.1+/-1.3 in healthy subjects, 4.1+/-2.1 in aPBC, 3.4+/-1.3 in chronic hepatitis C, and 3.6+/-2.3 in cirrhosis secondary to CH-C; p < 0.05 for sPBC vs all others). Histological examination of these patients showed that all aPBC patients belonged to relatively early stage (stage I-II) and 7 of 8 sPBC patients belonged to late stage (stage III-IV). Thus, our results suggest that, mainly as a result of the decline of Th2, a predominance of Th1 may exist in advanced stage PBC.

CONCLUSIONS

The present results demonstrated that a slight elevation of Th1 prevalence, as well as a significant decline of Th2 prevalence, was observed in peripheral blood of advanced stage PBC.

Developmental expression of GLUT2 in the rat retina

We previously demonstrated that GLUT2, a facilitated-diffusion glucose transporter isoform known to play critical roles in the regulation of systemic blood glucose level, is present at the apical ends of Müller cells in the rat retina. As a means of elucidating the ontogeny and possible role(s) of GLUT2 in the developing retina, this study examined its expression at various stages of retinal development by immunofluorescence staining using GLUT2-specific antibody. Evidence of GLUT2 expression first appeared at embryonic day 14 (E14) as linear staining along the boundary between the inner and outer layers of the optic cup, with this staining pattern being present throughout subsequent embryonic and neonatal stages. After the development of photoreceptor cell inner and outer segments (i.e., photoreceptor layer), GLUT2 immunoreactivity was localized along the boundary between the outer nuclear layer and photoreceptor layer. Localization of GLUT2 expression and the timing of its appearance, which coincided with the formation of choriocapillaries, together suggest that GLUT2 is involved in the anterior transport of glucose supplied by choroidal circulation from the early stages of retinal development.

Light and electron microscopic immunocytochemical study on the innervation of the pineal gland of the tree shrew (Tupaia glis), with special reference to peptidergic synaptic junctions with pinealocytes

Conventional and immunocytochemical, light- and electron-microscopic studies on the innervation of the pineal gland of the tree shrew (Tupaia glis) were made. Neuropeptide Y (NPY)-immunoreactive fibers, which were abundantly distributed in the gland, disappeared almost completely after superior cervical ganglionectomy, suggesting that these fibers are mostly postganglionic sympathetic fibers. By contrast, tyrosine hydroxylase (TH)-immunoreactive fibers, which were less numerous than NPY-fibers, remained in considerable numbers in ganglionectomized animals, indicating the innervation of TH-positive fibers from extrasympathetic sources. Bundles of substance P (SP)- or calcitonin gene-related peptide (CGRP)-immunoreactive fibers, entering the gland at its distal end, were left intact after ganglionectomy. SP-fibers were numerous, but CGRP-fibers were scarce in the gland. SP-immunoreactive fibers were myelinated and nonmyelinated, and were regarded as peripheral fibers because of the presence of a Schwann cell sheath. NPY- and SP-immunoreactive fibers and endings were mainly localized in the pineal parenchyma. NPY-immunoreactive endings synapsed frequently, and SP-positive ones did less frequently, with the cell bodies of pinealocytes. The results suggest that NPY and SP directly control the activity of pinealocytes. Sections stained for myelin showed that thick and less thick bundles of myelinated fibers entered the gland by way of the habenular and posterior commissures, respectively. Under the electron microscope, the bundles were found to contain also unmyelinated fibers. A considerable number of nerve endings synapsing with the cell bodies of pinealocytes remained in ganglionectomized animals; these endings were not immunoreactive for TH or SP. Such synaptic endings may be the terminals of commissural fibers.

Peptidergic peripheral nervous systems in the mammalian pineal gland

The distribution and density of tyrosine hydroxylase (TH) and neuropeptide Y (NPY)-immunoreactive, sympathetic fibers and calcitonin gene-related peptide (CGRP)-, substance P (SP)-, and vasoactive intestinal polypeptide (VIP)-immunoreactive, non-sympathetic fibers in the pineal gland, the effects of superior cervical ganglionectomy (SCGX) on these fibers, and the location of their terminals in the pineal gland were compared between rodents and non-rodents. A dense network of TH/NPY-positive fibers is present all over the pineal gland. A less dense network of CGRP/SP- or VIP-positive fibers occurs in the whole pineal gland of non-rodents, but these fibers are usually confined to the superficial pineal gland in rodents. After SCGX, some TH/NPY-fibers remain only in the deep pineal gland in rodents, whereas considerable numbers of these fibers persist throughout the gland in non-rodents. Thus, the remaining fibers, probably originating from the brain, may be more numerous in non-rodents. Since CGRP-, SP- or VIP-immunoreactive fibers in the pineal capsule can be traced to those in the gland, and since these fibers are ensheathed by Schwann cells, it is concluded that these fibers belong to the peripheral nervous system. However, the existence of SP-positive central fibers cannot be denied in some species. In the superficial pineal gland of rodents, sympathetic terminals are mostly localized in perivascular spaces, whereas the parenchymal innervation by sympathetic fibers in the pineal gland is more dense in non-rodents than in rodents. Synapses between sympathetic nerve terminals and pinealocytes occur occasionally in non-rodents, but only rarely in the superficial pineal gland of rodents. The occurrence of the synapses may depend on the frequency of intraparenchymal sympathetic terminals.

Eosinophilic gastroenterocolitis in iron lactate-overloaded rats

Eosinophilic gastroenterocolitis with peripheral eosinophilia was induced in rats fed a diet containing 2.5% or 5.0% iron lactate for 3 mo. Additional findings consistent with iron overload were also observed. Microscopically, the lesions consisted of eosinophilic infiltrations in the mucosa and submucosa along the whole length of the gastrointestinal tracts, increased surface area of the gastric mucosal propria covered with mucous cells, and increased apoptotic bodies in the gastric glandular neck of rats in the 2.5% and 5.0% groups. An increased number of intraepithelial globule leukocytes in the gastric and intestinal lamina propria was also observed in the 5.0% group. Globule leukocytes in the gastric mucosa contained obviously enlarged granules in their cytoplasm in these rats. The granules of the globule leukocytes were positive for rat mast cell protease II, suggesting the mastocyte origin of these cells. Although severe infiltration of eosinophils and globule leukocytes suggested a type-1 hypersensitivity reaction, other features such as an increasing vascular permeability were not detected. Serum IgE levels in the 5.0% and control groups were < 3 ng/ml. Final body weights of male and female rats of the 5.0% group were suppressed to 70% and 90%, respectively, of those of the control rats, whereas food consumption was comparable to that of the control group. The morphologic characteristics of the gastrointestinal lesions and peripheral eosinophilia induced in rats fed iron lactate were very similar to those in some cases of eosinophilic gastroenterocolitis in humans and other animals.

Colocalization of GLUT3 and choline acetyltransferase immunoreactivity in the rat retina

Toward elucidating the functional aspects ofGLUT3, a primary neuronal glucose transporter isoform in the vertebrate central nervous system, this study examined its expression in cholinergic amacrine cells made identifiable by the presence of acetylcholine-synthesizing enzyme, choline acetyltransferase (ChAT), in the rat retina. Double-immunofluorescence staining of adult rat retinal tissue with anti-GLUT3 and anti-ChAT antibodies revealed characteristic stratified GLUT3 immunoreactivity (GLUT3-IR) in the inner plexiform layer (IPL) that was identical to the arborization pattern of ChAT-positive neuronal processes there. In addition, approximately 30-50% of intensely GLUT3-immunoreactive cell bodies in the inner nuclear layer and ganglion cell layer showed ChAT-IR, while the majority of ChAT-positive cell bodies were also intensely GLUT3 immunoreactive. Analysis at the cellular level using retinal cells in culture revealed similar findings. These results collectively indicate that cholinergic amacrine cells constitute the major component of GLUT3-expressing cells in the rat retina. It is expected that the link demonstrated here between GLUT3 expression and cholinergic amacrine cell population will provide clues for further analyzing GLUT3 function in the retina.

alpha-soluble N-ethylmaleimide-sensitive factor attachment protein is expressed in pancreatic beta cells and functions in insulin but not gamma-aminobutyric acid secretion

The function of soluble N-ethylmaleimide-sensitive attachment protein-alpha (alpha-SNAP) in exocytosis still remains obscure. This study was conducted to determine the physiological role of alpha-SNAP in the secretion of insulin and gamma-aminobutryric acid (GABA) from pancreatic beta cells. Reverse transcriptase-polymerase chain reaction analysis of total RNA isolated from rat islets disclosed alpha-SNAP, but not beta-SNAP, mRNA expression, and an immunofluorescence study of rat pancreas showed that alpha-SNAP was present predominantly in the cytoplasm of the islets of Langerhans. alpha-SNAP overexpression in rat islets enhanced insulin release relative to the control levels. An in vitro binding study showed that both wild-type alpha-SNAP and C-terminal-deleted alpha-SNAP mutant (1-285) can bind to syntaxin 1A. alpha-SNAP mutant (1-285) was overexpressed to evaluate its activity as dominant-negative effector on insulin release. Overexpression of alpha-SNAP mutant (1-285) in rat islets and MIN6 cells decreased glucose-stimulated insulin release to about 50% of the control levels. Suppression of endogeneous alpha-SNAP in MIN6 cells by treatment with an antisense phosphorothioate oligonucleotide resulted in inhibition of insulin release. In order to examine if alpha-SNAP functions in exocytosis from synaptic-like microvesicles in pancreatic beta cells, the functional role of alpha-SNAP in GABA release from MIN6 cells was studied. The data showed no effect of alpha-SNAP mutant (1-285) overexpression on GABA release. We conclude that 1) alpha-SNAP plays a crucial role in insulin exocytosis via large dense core vesicles, but not GABA released via synaptic-like microvesicles, in pancreatic beta cells; and 2) the interaction of alpha-SNAP and syntaxin 1A may play an important role in the insulin exocytotic process.

Peripheral neuroblastoma in a young Beagle dog

A peripheral neuroblastoma was found in the abdominal cavity of a young male beagle dog. The large tumor mass involved the left kidney and both adrenal glands. Histologically, a major portion of the neoplasm consisted of lobulated sheets of small round cells with hyperchromatic nuclei mixed with polygonal cells and neuropil. Small clusters of polygonal cells with abundant eosinophilic cytoplasm and a trabecular growth pattern were observed adjacent to some of the tumor lobules. Small, round neoplastic cells metastasized to lumbar lymph nodes and also to the adrenal glands. The neoplastic cells were positive for neuron-specific enolase, synaptophysin, and neurofilament protein. Electron micrographs revealed intracytoplasmic dense core granules, microtubules, intermediate filaments, and desmosomes in the cytoplasm of the neoplastic cells.

Hyperthermic enhancement of cisplatin-induced generation of active oxygen radicals in a cell-free system

The interaction of cisplatin [cis-diamminedichloroplatinum (II), or DDP] with calf thymus DNA has previously been shown to result in the generation of superoxide anions (O2-) and hydroxyl radicals (OH) in a cell-free system. The effect of hyperthermia (42 degrees C) on the generation of such active oxygen radicals was examined by chemiluminescence of a Cypridina luciferin analog (CLA) with DNA extracted from a human ovarian cancer cell line (A2780). Hyperthermia significantly increased chemiluminescence of CLA (CCLA) 1.17- to 1.51-fold at DDP concentrations of 10 to 40 uM, relative to values at 37 degrees C. The extent of DDP-induced CCLA correlated significantly (r = 0.973) with that of DDP cytotoxicity in A2780 cells. These results suggest that hyperthermic enhancement of DDP-induced generation of active oxygen radicals contributes to the hyperthermic potentiation of DDP cytotoxicity.