Immunohistochemical localization of c-fos in the nuclei of the medulla oblongata in relation to asphyxia

Immunohistochemical Analysis of Brainstem Lesions in the Autopsy Cases with Severe Motor and Intellectual Disabilities Showing Sudden Unexplained Death

It is known that patients with severe motor and intellectual disabilities (SMID) showed sudden unexplained death (SUD), in which autopsy failed to identify causes of death. Although the involvement of brainstem dysfunction is speculated, the detailed neuropathological analysis still remains to be performed. In order to clarify pathogenesis, we investigated the brainstem functions in autopsy cases of SMID showing SUD. We immunohistochemically examined expressions of tyrosine hydroxylase, tryptophan hydroxylase, substance P, methionine-enkephalin, and c-fos in the serial sections of the midbrain, pons, and medulla oblongata in eight SUD cases and seven controls, having neither unexplained death nor pathological changes in the brain. Expressions of tyrosine hydroxylase and tryptophan hydroxylase were reduced in two of eight cases, and those of substance P and/or methionine-enkephalin were augmented in the pons and medulla oblongata in seven of eight cases, including the aforementioned two cases, when compared with those in controls. The hypoglossal nucleus and/or the dorsal vagal nucleus demonstrated increased neuronal immunoreactivity for c-fos in seven of eight cases, although there was no neuronal loss or gliosis in both the nuclei. Controls rarely showed immunoreactivity for c-fos in the medulla oblongata. These data suggest the possible involvement of brainstem dysfunction in SUD in patients with SMID, and consecutive neurophysiological evaluation of brainstem functions, such as all-night polysomnography and blink reflex, may be useful for the prevention of SUD, because some parameters in the neurophysiological examination are known to be related to the brainstem catecholamine neurons and the spinal tract nucleus of trigeminal nerve.

Fatal mechanical asphyxia induces changes in energy utilization in the rat brain: An (18)F-FDG-PET study

PURPOSE

This study was designed to evaluate changes in brain glucose metabolism in rats following ligature strangulation.

MATERIALS AND METHODS

Thirteen male Wistar rats were used in the present study, divided into control (n=7) and asphyxia groups (n=6, ligature strangulation). Positron emission tomography (PET) with 2-deoxy-2-[(18)F]fluoro-D-glucose ((18)F-FDG) was used to evaluate brain glucose metabolism. Rats were scanned for PET-CT, and image data co-registered with a T2WI MRI template using SPM8 software. Image J was employed to draw regions of interest (ROIs) from the MRI template and acquire ROI activity information from the PET images.

RESULTS

In the asphyxia group vs. controls, (18)F-FDG uptake (FU) was decreased in the substantia nigra (25.26%, p<0.001), rhombencephalon (pons/medulla oblongata, 13.92%, p<0.01), hypothalamus (22.06%, p<0.01), ventral tegmentum (10.12%, p<0.05) and amygdala (12.74%, p<0.05); however, FU was increased in motor (18.21%, p<0.05) and visual cortices (19.2%, p<0.05).

CONCLUSIONS

The glucose metabolism distribution map in the asphyxiated rat brains were substantially changed versus controls. PET with (18)F-FDG can demonstrate excitement and inhibition of different brain areas even in cases of ligature strangulation.

Neuropathology of the Guillain-Mollaret Triangle (Dentato-Rubro-Olivary Network) in Sudden Unexplained Perinatal Death and SIDS

The present study was undertaken to evaluate the possible alterations of the triangle of Guillain and Mollaret (G-Mt), a neuronal brainstem/cerebellum network (from the dentate nucleus to red nucleus and inferior olivary nucleus) already known for its involvement in the pathogenesis of the palatal myoclonus, in sudden unexplained perinatal and infant death. In 44 cases of perinatal and infant death victims, aged from 26 gestational weeks to 10 months of life, we investigated, besides the histological morphology of the three nuclei, the c-fos and apoptotic expression, as well as the possible effects elicited by maternal cigarette smoking.

A significant increase of lesions (hypoplasia and/or increased c-fos and apoptotic neuronal immunopositivity) of the three nuclei was found in unexplained death victims, compared with age-matched controls. These alterations were related to maternal cigarette smoking habit.

We postulated that the G-Mt is an important network involved in the pathogenesis of a wide spectrum of pathological manifestations and that maternal smoking during pregnancy can exert an adverse influence on this complex, even leading to sudden death in vulnerable periods of perinatal or infant development.

Hyperventilation evoked by activation of the vicinity of the caudal inferior olivary nucleus depends on the fastigial nucleus in anesthetized rats

Several studies have demonstrated that cerebellar deep nuclei, particularly the rostral fastigial nucleus (FNr), are involved in respiratory modulation. These nuclei receive inputs from the contralateral caudal inferior olivary nuclei of the medulla. The objectives of this study were to determine whether electrical and chemical activation of the vicinity of the caudal inferior olivary nuclei (vIOc) affected respiration and, if true, whether the FNr was involved in the vIOc stimulation-evoked ventilatory responses. Experiments were conducted in 30 anesthetized and spontaneously breathing rats. Our results showed that 1) electrical (25 or 100 μA at 10 or 20 Hz for 10 s) and chemical (1 or 100 mM, 25–50 nl N-methyl-d-aspartate) stimulation of the vIOc augmented ventilation predominantly via increasing tidal volume; 2) the responses to the electrical stimulation were almost eliminated by lesion of the contralateral FNr via microinjection of ibotenic acid; and 3) the respiratory responses to electrical stimulation in the vicinity of the rostral IO were 65–70% smaller compared with that evoked by vIOc stimulation. These findings strongly suggest that vIOc neurons play a significant role in modulation of respiratory activity, largely depending on their projections to the FNr.

Immunohistochemical investigation of ubiquitin and myoglobin in the kidney in medicolegal autopsy cases

We examined the immunohistochemical distributions of ubiquitin (Ub) and myoglobin (Mb) in human kidney tissues to assist the pathological assessment of death due to trauma. Medicolegal autopsy cases at our institute (n=138: 0-96 years of age, 105 males and 33 females) were examined. Causes of death were blunt injury (n=31), sharp injury (n=15), poisoning (n=11), drowning (n=10), fire fatalities (n=25), hypothermia (n=7), asphyxiation (n=14), hyperthermia (n=3), and natural diseases (n=22) for controls. Immunostaining of Ub and Mb was performed on the formalin-fixed paraffin-embedded kidney tissue sections. Quantitative analyses by estimating the proportion of Ub- and Mb-positive cells (%positivity) of renal tubule epithelial cells showed that the positivities for Ub and Mb were higher in subjects who died due to fire, blunt injury, sharp injury and fatal hypothermia than in other groups. The Ub-positivity correlated with the severity of airway thermal injury in fire deaths, survival time in blunt injury, and serum markers for renal failure in deaths due to sharp injury. Concomitant increases in the tubular Mb- and Ub-positivities were characteristic to deaths from injury and hypothermia. These findings suggest that Ub may serve as a sensitive indicator of the fatal influence of traumas.

Immunohistochemical study on the expression of c-Fos and c-Jun in human skin wounds

An immunohistochemical study on the temporal expression of c-Fos and c-Jun, both of which designate proto-oncogene products, was performed on 60 human skin wounds with different post-infliction intervals. In unwounded skin, c-Fos or c-Jun was immunolocalized at the nuclei of the epidermal cells in the basal layer, hair follicle cells and sweat gland cells. During the early inflammatory phase of wound healing, the nuclei of polymorphonuclear cells (probably neutrophils), mainly infiltrating at the wound site, were labeled with anti-c-Fos or -c-Jun antibody. As the wound age increased, the neutrophils had disappeared at the wound site, and both mononuclear cells (probably macrophages) and spindle-shaped fibroblastic cells, which expressed a c-Fos or c-Jun positive reaction in the nuclei, were mainly observed. Morphometrically, the distribution of the c-Fos-positive ratio was very similar to that of the c-Jun-positive ratio; the positive ratio was considerably increased in wound specimens with a post-infliction interval of > or = 1 day, thus indicating the late inflammatory or proliferative phase. This study showed that c-Fos and c-Jun were closely involved in the inflammatory phase as well as the proliferative phase of the wound healing process.