N-methyl-D-aspartate receptor subunit NR2B is widely expressed throughout the rat diencephalon: an immunohistochemical study

Glutamate (Glu), a major excitatory neurotransmitter within the hypothalamus and thalamus, acts upon many receptors, including the N-methyl-D-aspartate (NMDA) subtype. Abundant evidence suggests that variations in the subunit composition of NMDA receptors (NMDA-Rs) contribute to differences in Glu's immediate electrophysiological effects as well as to the patterns of signal transduction cascades it triggers to mediate long-term changes in neuronal function. We have previously shown that hypothalamic NMDA-Rs containing the NR2B subunit may be involved in the control of eating as well as in the mediation of physiological responses to osmotic stimuli. To broaden our understanding of diencephalic NMDA-R participation in other functions, we localized the NR2B subunit in the diencephalon of the adult male rat using immunoperoxidase, immunogold, and immunofluorescence techniques and an affinity-purified polyclonal antibody specific for the NR2B subunit of the NMDA-R. In addition, we used a monoclonal NR2B antibody with immunoperoxidase detection to confirm the NR2B distribution seen with the polyclonal antibody. In the hypothalamus, the highest levels of NR2B immunoreactivity (-ir) were found in the magnocellular neurosecretory system, including the paraventricular and supraoptic nuclei. A new finding was that intense NR2B-ir was present within perivascular "accessory" magnocellular groups of this system, including the nucleus circularis, anterior fornical nucleus, and scattered clusters of lateral hypothalamic cells apposed to blood vessels. Robust NR2B-ir was also present within the arcuate nucleus, the median eminence, and the tuberal nucleus, and light immunostaining was found in all other hypothalamic nuclei examined. In the thalamus, the highest NR2B-ir was observed in the medial habenula and the anterodorsal, paraventricular, rhomboid, reticular, and dorsal lateral geniculate nuclei. As in the hypothalamus, all thalamic nuclei examined displayed at least light immunostaining for this subunit. Control sections, including those incubated with the polyclonal NR2B antibody preadsorbed with its fusion protein, were virtually devoid of immunostaining. This demonstration that the NR2B subunit of the NMDA-R is widely distributed in the diencephalon, implicates it in a wide variety of functions, and provides a useful anatomical framework for establishing a comprehensive map of Glu receptor populations within this major subdivision of the brain.     

Effects of skyrin, a receptor-selective glucagon antagonist, in rat and human hepatocytes

Peptidic glucagon antagonists have been shown to lower blood glucose levels in diabetic models (1-3), but attempts to identify small molecular weight glucagon receptor-binding antagonists have met with little success. Skyrin, a fungal bisanthroquinone, exhibits functional glucagon antagonism by uncoupling the glucagon receptor from adenylate cyclase activation in rat liver membranes (1). We have examined the effects of skyrin on cells transfected with the human glucagon receptor and on isolated rat and human hepatocytes. The skyrin used was isolated from Talaromyces wortmanni American Type Culture Collection 10517. In rat hepatocytes, skyrin (30 micromol/l) inhibited glucagon-stimulated cAMP production (53%) and glucose output (IC50 56 micromol/l). There was no detectable effect on epinephrine or glucagon-like peptide 1 (GLP-1) stimulation of these parameters, which demonstrates skyrin's selective activity. Skyrin was also evaluated in primary cultures of human hepatocytes. Unlike cell lines, which are largely unresponsive to glucagon, primary human hepatocytes exhibited glucagon-dependent cAMP production for 14 days in culture (EC50 10 nmol/l). Skyrin (10 micromol/l) markedly reduced glucagon-stimulated cAMP production (55%) and glycogenolysis (27%) in human hepatocytes. The inhibition of glucagon stimulation was a specific property displayed by skyrin and oxyskyrin but not shared by other bisanthroquinones. Skyrin is the first small molecular weight nonpeptidic agent demonstrated to interfere with the coupling of glucagon to adenylate cyclase independent of binding to the glucagon receptor. The data presented in this study indicate that functional uncoupling of the human glucagon receptor from cAMP production results in metabolic effects that could reduce hepatocyte glucose production and hence alleviate diabetic hyperglycemia.     

Retrograde nailing of femur fractures in patients with myelopathy and who are nonambulatory

The authors studied 10 consecutive patients with closed femoral shaft or supracondylar fractures who were nonambulatory and who were treated by reamed retrograde intramedullary nailing via an intercondylar notch approach. The study consisted of five women and five men with an average age of 60.7 years (range, 40-89 years). Six patients had spinal cord lesions, one had a brain injury, one had cerebral palsy, one had multiple sclerosis, and one had progressive myelopathy. Three fractures were supracondylar, and seven fractures involved the mid-distal diaphysis. The average time of surgery was 110 minutes (range, 70-225 minutes) with an average estimated blood loss of 288 mL (range, 150-400 mL). There were two postoperative deaths (at 15 days and 2 months, respectively) after the procedure that were attributable to pneumonia. The remaining eight patients were observed for an average of 13 months (range, 6-20 months) after surgery. All fractures healed as evaluated radiographically. Retrograde intramedullary nailing is a simple, safe, and effective alternative to nonoperative treatment for femoral shaft or supracondylar fractures in patients who are nonambulatory. Stabilization by this method allows fracture healing and rapid return of patients to their previous level of function. There were no nonunions, malunions, significant shortening, implant failure, or wound infections.     

Video-fluoroscopic study of swallowing in children with neurodevelopmental disorders

BACKGROUND: Children with neurodevelopmental disorders can have feeding problems. Malnutrition and recurrent aspiration pneumonia can increase the risk of morbidity and mortality. Video-fluoroscopic study of swallowing (VFSS) is essential in understanding the pathological mechanisms involved during swallowing. METHODS: The aim of the present study was to assess the role of VFSS in assessment and management of four children with various neurodevelopmental disorders in a multidisciplinary feeding team. We describe the team approach, with the participation of child neurologist, radiologist with the rehabilitation team including the speech therapist, occupational therapist and dietician, in the assessment and plan of management. RESULTS: Video-fluoroscopic study of swallowing had been useful in assessing the type of swallowing problems with treatment goals targeted to the basic underlying pathophysiological mechanism. CONCLUSION: A child neurologist should be involved in the multidisciplinary oromotor rehabilitation program for neurologically impaired children with feeding problems.     

Congenital cysts of the third and fourth pharyngeal pouches or pyriform sinus cysts

Cysts arising from the III and IV pharyngeal pouches, although uncommon, are typical in their presentation. They occur in neonates, invariably in the left anterior neck and cause respiratory distress. Excision of the cyst with ligation of the tract at the level of the pyriform sinus is curative.     

小肠无管法动力位双对比造影的价值分析

目的　介绍一种简易的小肠双对比造影法———小肠动力位无管法双对比造影。方法　口服钡剂进入小肠后再服产气粉 ,通过改变体位及配合促胃肠蠕动药物的使用 ,使气体进入小肠形成双对比相。对照组采用传统方法。结果　试验组小肠疾病阳性检出率显著高于对照组。结论　小肠动力位无管法双对比造影是小肠疾病检查的首选方法     

Histologic changes in the eustachian tube mucosa of rats after short-term exposure to cigarette smoke.

OBJECTIVE AND BACKGROUND: It is generally accepted that cigarette smoke is a major risk factor for middle ear disease. However, the literature is void of articles addressing the direct relationship between cigarette smoke exposure and middle ear disease. Furthermore, there are many conflicting opinions concerning the role of cigarette smoke in the pathogenesis of middle ear disease. The purpose of this study was to evaluate the effects of cigarette smoke on the Eustachian tube mucosa. MATERIALS AND METHODS: Thirty healthy 150 to 230 g Sprague Dawley rats with normal middle ears were used. The animals were divided into six groups of five. Five experimental groups (N=5 each) were exposed to a domestic cigarette (This, tar 7.0 mg, nicotine 0.75 mg) every 30 minutes (total 2.5 hours, 5 cigarettes total) on a daily basis in a smoking chamber for 1, 2, 4, 6, or 8 weeks. A control group (N=5) was placed in the same chamber without exposure to cigarette smoke. After exposure, the animals were sacrificed and cross sections of the Eustachian tubes were prepared. Histologic changes of the Eustachian tube mucosa were observed through light and electron microscopes. RESULTS: Loss of cilia, goblet cell depletion, and squamous metaplasia of the Eustachian tube mucosa were observed following exposure to smoke. The one- and two-week exposure groups demonstrated the greatest decrease in goblet cell counts. The eight-week exposure group showed recovery from this decrease. Squamous metaplasia was observed in all experimental groups and was most prominent in the eight-week exposure group. CONCLUSION: These findings suggest that cigarette smoke directly affects Eustachian tube mucosa in the early stages of exposure. Some of the mucosal changes, however, were reversed during the latter stages of exposure. A mechanism different from that which occurs in the nasal cavity and trachea may be activated in the Eustachian tube after exposure to passive smoke. The protective function of the Eustachian tube may play some role in this mechanism.     

Neuroprotective strategies in parkinson’s disease: protection against progressive nigral damage induced by free radicals

Brain undergoes neurodegeneration when excess free radicals overwhelm antioxidative defense systems during senescence, head trauma and/or neurotoxic insults. A site-specific accumulation of ferrous citrate-iron complexes in the substantia nigra dopaminergic neurons could lead to exaggerated dopamine turnover, dopamine auto-oxidation, free radical generation, and oxidant stress. Eventually, this iron-catalyzed dopamine auto-oxidation results in the accumulation of neuromelanin, a progressive loss of nigral neurons, and the development of Parkinson's disease when brain dopamine depletion is greater than 80%. Emerging evidence indicates that free radicals such as hydroxyl radicals ((.-)OH) and nitric oxide ((.-)NO) may play opposite role in cell and animal models of parkinsonism. (.-)OH is a cytotoxic oxidant whereas oNO is an atypical neuroprotective antioxidant. (.-)NO and S-nitrosoglutathione (GSNO) protect nigral neurons against oxidative stress caused by 1-methyl-4-phenylpyridinium (MPP(+)), dopamine, ferrous citrate, hemoglobin, sodium nitroprusside and peroxynitrite. MPP(+), the toxic metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), increases the nigral uptake of iron complexes and dopamine overflow leading to the generation of (.-)OH, protein oxidation, lipid peroxidation, and associated retrograde degeneration. In addition to GSNO, MPP(+)-induced oxidative neurotoxicity can be prevented by antioxidants including selegiline, 7-nitroindazole, 17beta-estradiol, melatonin, alpha-phenyl-tert-butylnitrone and U78517F. Similar to selegiline, 7-nitroindazole is a MAO-B inhibitor, which blocks the bio-activation of MPTP and oxidative stress. Freshly prepared but not light exposed, (.-)NO-exhausted GSNO is about 100 times more potent than the classic antioxidant glutathione. Via S-nitrosylation, GSNO also inhibits proteolysis and cytotoxicity caused by caspases and HIV-1 protease. Furthermore, in addition to protection against serum deprivation stress, the induction of neuronal NOS1 in human cells increases tolerance to MPP(+)-induced neuro-toxicity since newly synthesized (.-)NO prevents apoptosis possibly through up-regulation of bcl-2 and down regulation of p66(shc). In conclusion, reactive oxygen species are unavoidable by-products of iron-catalyzed dopamine auto-oxidation, which can initiate lipid peroxidation, protein oxidation, DNA damage, and nigral loss, all of which can be prevented by endogenous and exogenous (.-)NO. Natural and man-made antioxidants can be employed as part of preventative or neuroprotective treatments in Parkinson's disease and perhaps dementia complexes as well. For achieving neuroprotection and neuro-rescue in early clinical parkinsonian stages, a cocktail therapy of multiple neuroprotective agents may be more effective than the current treatment with extremely high doses of a single antioxidative agent.