Chronic hypoxia induced ultrastructural changes in the rat adrenal zona glomerulosa

The adrenal cortex plays an important role in adaptation to various forms of stress, including hypoxia. While physiological changes in the aldosterone metabolism during hypoxia have been extensively described, few studies have focused on the morphological changes in the adrenal glands under chronic hypoxia. We studied the ultrastructure of the zona glomerulosa of 6-month-old Wistar rats exposed to chronic normobaric hypoxia. Animals were divided into two groups: control (n=12) and hypoxic (n=12). In this latter group, the animals were kept at 7% O2 concentration after a gradual adaptation (21, 15, 12, 10, 8, 7 vol% O2). The duration of the study was 112 days. In comparison with normoxic rats, body weight and adrenal gland weight of hypoxic animals was significantly reduced by 18.5% (p=0.006) and 14.7% (p=0.001) respectively. The thickness of the zona glomerulosa decreased due to atrophy of cells. The main ultrastructural changes observed were: 1) a decrease in, or complete elimination of, lipid droplet content; 2) a marked increase in lysosome number; and 3) the presence of giant mitochondria. Our findings show that rats fail to adapt to severe chronic hypoxia. The ultrastructural changes in the zona glomerulosa found in the present study could reflect changes in the aldosterone pathway.

Effects of chronic deep hypoxia on the expression of nitric oxide synthase in the rat brain

Experimental studies in extreme hypoxic conditions affecting the brain have been performed mainly in acute but not chronic models. Twenty rats were housed and exposed to decreasing concentrations of oxygen (from 21% to 7% over 130 days) and ten normal rats were used as control. Paraffin slices from representative sections containing cerebral cortex, cerebellum, striatum, hippocampus, thalamus and hypothalamus were incubated with antisera against nitric oxide synthase. Cortex and striatum showed small randomly distributed positive neurons with bipolar features, in greater numbers in the hypoxic group (p < 0.02). The granular layer of the cerebellum showed a strongly positive rim around some cell nuclei. Purkinje cells were immunopositive in hypoxic rats. Hipoccampal, thalamic and hypothalamic nuclei showed no quantitative differences in the number of positive neurons. The increased number of blood vessels and their dilation observed in some brain regions in hypoxic rats, mainly in ventral striatum, lead us to hypothesise that NOS may be overexpressed and act at these sites as vasomodulator and/or mediator of secondary cell injury affecting selective neuronal populations. We conclude that prolonged periods of adaptation to deep hypoxia reduces the effect of hypoxia on the upregulation of NOS in the brain tissue.

Short-term neuropathological aspects of in vivo suicide gene transfer to the F98 rat glioblastoma using liposomal and viral vectors

To date, only few preclinical protocols on liposomal suicide gene transfer in tumors have been published, none of which directly compared viral to liposomal vectors in terms of immunoreactivity and efficacy. We thus studied the neuropathological alterations in 80 rats being treated for glioblastoma using liposomal and, for comparison, adenoviral and retroviral suicide gene transfer approaches to identify vector-associated efficacy and toxicity for further clinical studies. 62 rats served as controls. F98 tumors were established in Fisher rats and transfected in vivo with the thymidine kinase gene of herpes simplex virus (HSVtk) by a single intratumoral application and an implanted intratumoral continuous delivery system. Three days later ganciclovir was given intraperitoneally for 14 days. The animals were sacrificed 17 days post completed gene transfer. Brains were examined histologically and immunohistochemically using markers for immunocompetent cells. Ten animals showed complete tumor regression; they all belonged to the liposomal and adenoviral groups. In 6 of 10 experimental groups considerable numbers of lymphocytes along the margins of the regression cavities could be observed. Control animals of the liposomal and adenoviral groups showed only little lymphocytic infiltration, underlining the minimal immunogenicity of these carriers. In contrast, the retroviral control group featured a high lymphocyte infiltration. In summary, this study indicates that, in terms of both efficacy and immunoreaction, liposomes are as appropriate as adenoviruses in the treatment of rat glial tumors using suicide gene transfer strategies.

Voltage- and gamma-aminobutyric acid-activated membrane currents in the human medulloblastoma cell line MHH-MED-3

The whole-cell patch clamp technique was used to characterize voltage- and neurotransmitter-activated currents in the medulloblastoma cell line MHH-MED-3 and cells from tissue slices and primary cultures of two medulloblastoma biopsies. These preparations revealed similar electrophysiological properties. All tested cells displayed 4-aminopyridine-sensitive delayed rectifying K(+) currents, gamma-aminobutyric acid(A) receptor-mediated Cl(-) currents and most of them inward rectifier K(+) currents. Transient inward currents were mainly carried by low-voltage activated T-type Ca(2+) channels in MHH-MED-3 cells, and tetrodotoxin-sensitive Na(+) channels in cells from the primary culture. From these characteristics we conclude that medulloblastoma cells share physiological features with developing cerebellar granule cells at an immature stage.

Novel twelve-generation kindred of fatal familial insomnia from germany representing the entire spectrum of disease expression

We present a novel large German kindred of fatal familial insomnia (FFI) consisting of three branches and comprising more than 800 individuals of 12 generations, the largest pedigree of any familial prion disease known today. There is a wide spectrum of clinical presentations leading to misdiagnoses of Olivo-Ponto-Cerebellar Atrophy (OPCA), Parkinson's or Alzheimer's disease in addition to Creutzfeldt-Jakob disease (CJD) and Gerstmann-Sträussler-Scheinker (GSS) syndrome. Molecular genetic analysis of the prion protein gene (PRNP) confirmed the mutation D178N segregating with methionine at the polymorphic codon 129 of PRNP in all 7 patients examined. This polymorphism at codon 129 is supposed to discriminate between familial CJD (fCJD) and FFI; the 129M allele determines FFI and 129V fCJD. Furthermore, heterozygosity at this site appears to induce prolonged disease duration as compared to the homozygous condition. The variability of the clinical and pathological findings documented for our patients indicates the difficulty in establishing the diagnosis of FFI on clinical and on pathological grounds alone. In three cases (IX-97, XI-21, V-2) followed up by us prospectively insomnia was an early and severe symptom; however, in case notes analyzed retrospectively this symptom was frequently missed. In contrast to previous reports and in agreement with recent studies we cannot confirm a clear relationship between the status of the M/V polymorphism at codon 129 and the age-of-onset of this disease.

Craniocerebral trauma induces hemorheological disturbances

Several mechanisms are involved in the development of secondary ischemic brain damage, including microthrombi formation, which is thought to play a prominent role. Ninety-four autopsy cases were macro- and microscopically examined by specific staining for fibrin, 74 of which showed cortical contusion after a craniocerebral trauma. Twenty cases with no neurological pathology were used as controls. Traumatic cases comprised 52 males and 22 females, with a mean age of 48 years; most cases died in the first 48 h. The total number of fibrinous microthrombi in a slice of each hemisphere was determined. The mean number of microthrombi found in contused hemisphere was 152 (37-283), with 88 in the contralateral hemisphere (21-139) as compared to 13 (0-27) in control cases. Differences were statistically significant. Globular microthrombi or "shock bodies" (2-60 micro diameter) were present in five cases. Enhanced presence of microthrombi in contused brain areas, higher incidence in young people, an increase in the amount of microthrombi up to the 9th day after injury and involvement of the contralateral hemisphere free of contusion foci were all demonstrated. Microthrombi would therefore seem to be one of the central secondary events after brain trauma to bear in mind when designing treatment strategies.

NGF content in the cerebral cortex of non-demented patients with amyloid-plaques and in symptomatic Alzheimer's disease

There is increasing evidence that in Alzheimer's disease nerve growth factor (NGF) protein and NGF mRNA content in postmortem cortex is not decreased, but may even be elevated although the NGF-sensitive cholinergic basal forebrain neurons are preferentially affected. However, only little is known about the early pathophysiological events leading to Alzheimer's disease. We therefore measured the post-mortem NGF concentrations in temporal and frontal cortex of Alzheimer's disease patients, non-demented controls without Alzheimer's disease-related pathology, as well as non-demented patients with beta A4 plaques who might be classified as 'preclinical' cases. In the Alzheimer's disease group we found up to 43% increase in NGF concentrations in the frontal and temporal cortex as compared to the two other groups. In a subgroup analysis of the non-demented patients with plaques, NGF concentrations were lower in the frontal cortex when beta A4 plaques were present (46% of the control temporal area) than in patients without evidence of frontal plaques (81% of the control temporal area). This NGF decrease was paralleled to a similar decrease of choline acetyltransferase activity, which is regulated by NGF in the cholinergic basal forebrain. These findings support the hypothesis of lower cortical NGF content at the onset of plaque formation and of elevated NGF levels in the clinically manifest and neuropathologically advanced stage of the disease.

Upregulation of vascular endothelial growth factor in severe chronic brain hypoxia of the rat

The vascular endothelial growth factor (VEGF) has been shown to be upregulated in acute hypoxia. Although an increase in blood vessel number has been described in severe chronic brain hypoxia, it is unclear whether VEGF is upregulated in this condition. We therefore investigated male inbred Wistar rats, which were exposed for 9 to 13 weeks to decreasing amounts of oxygen, down to 7% O2 (15%: 15 days; 12%, 10%, respectively; 8%: 1 day, 3 weeks, respectively; 7%: 4 weeks). The expression of VEGF was studied by Northern analysis and in situ hybridization in frozen sections of cerebral cortex, hippocampus and cerebellum in six chronic hypoxic and two control rats. We found a marked upregulation of VEGF mRNA in all brain regions investigated, being strongest in cerebral cortex and cerebellum. Our results suggest a potential role of VEGF for vascular growth and vascular permeability observed in chronic cerebral hypoxia.

Adult neuronal ceroid lipofuscinosis with clinical findings consistent with a butterfly glioma. Case report

The authors report a case of neuronal ceroid lipofuscinosis (Kufs' disease) confirmed by stereotactically obtained brain biopsy findings and initially diagnosed as a butterfly glioma. The presenting symptoms in the 64-year-old patient were mental alterations with progressive dementia, followed by muscular atrophy and myoclonia with distal preponderance. The mild initial disturbances of coordination increased, and the patient developed a markedly ataxic gait. Computerized tomography (CT) scanning and magnetic resonance imaging revealed generalized cerebral atrophy and a bifrontal space-occupying lesion involving the callosum. The original "clearcut" diagnosis of glioblastoma multiforme, based on CT scans, was unexpectedly disproved by examination of stereotactically obtained brain biopsy specimens, which revealed a neuronal ceroid lipofuscinosis (Kufs' disease). To the authors' knowledge, this is the first report of a case presenting with both diffuse brain atrophy and localized accumulation of neuronal lipofuscin, mimicking a mass lesion on radiological studies.

Degenerative changes in unmyelinated nerve fibers in late-infantile neuronal ceroidlipofuscinosis. A morphometric study of conjunctival biopsy specimens

Late-infantile neuronal ceroidlipofuscinosis (LINCL) is an autosomal recessive disease involving rapidly progressive myoclonic epilepsy, mental and motor regression and progressive visual failure. Neurodegeneration and deposition of fluorescent lipid bodies are the neuropathological hallmarks of this disease. In this study we examined the conjunctival biopsy (CB) specimens of three siblings and two unrelated patients with LINCL. At the time of examination each of three siblings presented a different stage of the disease. The unrelated patients were examined at an advanced stage of LINCL. The findings in these patients are compared to the normal data derived from analysis of seven age-matched 9- to 41-month-old healthy subjects. In young children with LINCL the distribution of unmyelinated fiber (UF) diameter is unimodal. In advanced disease there is a bimodal distribution and a significant reduction of UF density and of relative UF area. As the disease progresses, degenerative changes can be demonstrated: at first a diffuse UF swelling, followed by a decrease of UF density and finally the increase of regenerates (microaxons). These changes, however, seem to reflect an unspecific reaction to nerve injury. They can be demonstrated in a variety of conditions of different pathophysiology such as diabetes mellitus, crush injury and normal aging. This is the first morphometric study of CB specimens. Normal data of UF distribution (unimodal, mode at 0.4-0.6 micron) and UF density (1447,760 +/- 19,347/mm2) in CB specimens correspond well to age-specific data published on the sural nerve.

The effect of Dotarizine (Ca2+ channel blocker) on cerebral vessel reactivity in animals subjected to hyperventilation and anoxia

Dotarizine--a novel piperazine derivative--belongs to wide spectrum Ca+ channel antagonists. It was reported to have strong vasodilatory and antiserotoninergic activities. Unlike other Ca+ channel blockers Dotarizine was found to have lower oral toxicity. In the presented study the influence of the oral administration of the novel compound on the blood flow velocity changes in different cerebral arteries--in basilar artery (BA) and middle cerebral artery (MCA)--was investigated under hyperventilation and hypoxic conditions of rabbits. In the first experimental group 25 mg/kg of Dotarizine dissolved in 0.25% agar was administered orally three times at the 10 hours' intervals. The sham group of animals was fed with agar of the same concentration. The results revealed that oral administration of Dotarizine diminished the vasoconstrictive effect of hyperventilation and this was more pronounced in MCA than in BA. During anoxic conditions stronger vasodilatory effects were observed in both groups of vessels and the low value of pulsatility index (PI) reflected pronounced decrease of the peripheral resistance, in comparison to the control group. Thus, the oral administration of Dotarizine decreases the peripheral resistance of cerebral vessels and therefore seems to have influence on the minute arteries of cerebrovascular system of the brain.

Role of neurochemicals in brain edema and cell changes following hyperthermic brain injury in the rat

The involvement of three potent neurochemical mediators of the edema formation such as serotonin, prostaglandins and opioids in the pathophysiology of hyperthermic brain injury was examined in a rat model using a pharmacological approach. Hyperthermic brain injury was induced in conscious young rats by exposing them to heat stress at 38 degrees C for 4 h. In these rats the blood-brain barrier (BBB) permeability, brain edema, cerebral blood flow (CBF), heat shock protein 72 kD (HSP) response and cell changes were examined. Pretreatment with ketanserin (a serotonin-2 receptor antagonist), indomethacin (prostaglandin synthesis inhibitor) and naloxone (opioid receptor antagonist) in separate groups of rats reduced hyperthermia and HSP response following heat stress and significantly attenuated changes in the BBB permeability, brain edema, CBF and cell reaction. These results suggest that the pathophysiology of hyperthermic brain injury is a complex mechanisms and several neurochemicals are involved in the brain pathology caused by heat stress.

Lectinhistochemistry of mixed gliomas demonstrating an intermediate cell type

18 cases of low-graded mixed gliomas were studied using the two lectins Concanavalin A (Con A) and Peanut lectin (PNA). Con A stained cytoplasm and processes of tumoral astrocytes, whereas PNA stained cell membranes of tumoral oligodendrocytes. Con A and PNA are reliable markers for astrocyte and oligodendrocyte areas of mixed gliomas, respectively. A part of cells were overlappingly positive for both lectins. They expressed an oligosaccharide pattern of both glioma types and represented a third, intermediate cell type of mixed gliomas. The existence of intermediate cells close to astrocytic and oligodendroglial cell types in mixed gliomas could result from transformation processes of neoplastic glial cells or from the malignant transformation of a common glial precursor cell.

p53 mutation and protein alteration in 50 gliomas. Retrospective study by DNA-sequencing techniques and immunohistochemistry

Alterations of the p53 protein, which is a 53 kD phosphoprotein and gene product of the p53 gene, has been found to play a major role in the genesis of a variety of human malignancies including tumors of the central nervous system. We investigated 50 tumor specimens from primary central nervous system neoplasms. Tissue samples were screened for mutations by the single-strand conformation polymorphism method and detected mutations were sequenced. All tissue specimens were stained immunohistochemically for p53 protein, which when altered accumulates in the nucleus due to prolonged half-life. Mutations were found in six cases, including one pilocytic astrocytoma World Health Organization (WHO) grade I, two astrocytomas WHO grade II, two anaplastic astrocytomas WHO grade III, and one primitive neuroectodermal tumor (PNET). In terms of relative frequency mutations were found mostly in the group of anaplastic astrocytomas WHO grade III. Interestingly, no mutations were found in the group of investigated glioblastomas. P53 immunopositivity did not correlated with the mutations found, whereas the staining index was significantly higher in the cases with detected mutations than in those without. When p53 alterations is seen as an indicator for different pathogenic pathways in glioma formation, this study gives evidence for a difference between anaplastic astrocytoma and glioblastoma. However, since there was a great overlap in p53 immunopositivity and p53 mutation in tumors of different WHO grades and entities, it seems that p53 will not act as a marker molecule neither for tumor entities nor for tumor malignancy.

Cerebral angiogenesis triggered by severe chronic hypoxia displays regional differences

The blood vessels in the brains of adult rats subjected to chronic normobaric hypoxia and control animals housed under normoxic conditions were morphometrically studied. Hypoxic male inbred Wistar rats were exposed over a period of 130 days to decreasing amounts of oxygen starting from 21% down to 7% (15%: 15 days; 12%, 10%, 8%: 22 days, respectively; 7%: 49 days). Areas of cerebral cortex, striatum, hippocampus, cerebellum, and medulla oblongata were investigated. The ratio vessel number per mm2 tissue and the average vessel size were measured using a Quantimet Q570. In the hypoxic animals, cerebral cortex, striatum, and hippocampus showed a significant increase of the vessel density per mm2 tissue (P < 0.01 or P < 0.05). The differences in both groups were highest in the striatum and hippocampus. In the cerebellum and the medulla oblongata of hypoxic animals, only a tendency to higher vessel numbers per mm2 tissue was found. The average blood vessel size differed only in the cerebral cortex and the cerebellum, but not in the other brain regions tested. The results indicate that the adaptation of the brain circulation to hypoxia is achieved by both angiogenesis and dilatation of microvessels, and that the pattern of the microcirculatory changes is not homogenous in all regions.

Involvement of nitric oxide in the pathophysiology of acute heat stress in the rat. Influence of a new antioxidant compound H-290/51

The possibility that nitric oxide (NO) is involved in the pathophysiology of brain injury caused by heat stress (HS) was examined using immunohistochemistry of a constitutive isoform of neuronal nitric oxide synthase (c-NOS) in a rat model. In addition, to discover the role of oxidative stress in inducing c-NOS activity in HS, the effect of a new antioxidant H-290/51 on HS-induced expression of c-NOS immunoreactivity was examined. Subjection of conscious young animals to a 4-h HS in a biological oxygen demand (BOD) incubator at 38 degrees C resulted in marked upregulation of c-NOS in the cerebral cortex and hippocampus of stressed rats compared to normal rats kept at room temperature (21 +/- 1 degrees C). The c-NOS immunoreactivity was found in distorted neurons located in the edematous regions not normally showing c-NOS activity. Pretreatment with H-290/51 significantly attenuated the upregulation of c-NOS in animals subjected to HS, and the signs of neuronal distortion and edema were less pronounced. These results suggest that HS has the capacity to induce upregulation of c-NOS, and these effects can be reduced by prior treatment with H-290/51, indicating a possible neuroprotective effect of antioxidants in thermal brain injury.

Action potential-generating cells in human glioblastomas

We studied the electrophysiological properties of cells from human glioblastomas obtained after surgery. The membrane currents were compared in cells of acute tissue slices and primary cultures using the whole cell mode of the patch-clamp technique. Very strikingly, in about a third of the tumor cells in situ and in vitro, depolarizing voltage steps elicited large, tetrodotoxin-sensitive inward currents with a threshold of about -30 mV, indicating the presence of voltage-gated sodium channels. In addition, three types of potassium currents, a delayed rectifying, an A-type, and an inward rectifying, were observed. Such a set of voltage-gated channels is characteristic for neurons. Indeed, in these glioblastoma cells, depolarizing current pulses in the current clamp mode were able to generate action potentials with properties similar to those observed in neurons. We interpret this finding as the ability of glioblastoma cells to acquire neuronlike properties but retain some glial features, since they still express markers typical for astrocytes and their precursors. The role of sodium channels in glioblastoma cells is unclear at this moment and needs further investigation. Our findings, however, imply that the tumor tissue can be intrinsically excitable and that neoplastic glial cells themselves may be an etiologic factor for epileptic seizures.

Lectin histochemistry of ethylnitrosourea-induced oligodendrogliomas in the rat

Oligodendrogliomas (n = 26) induced by ethylnitrosourea (ENU) in wistar rats were examined to assess the lectin specificity to oligodendroglial membranes. Two different types of oligodendrogliomas were found in our material: an isomorphous type (n = 12), and a polymorphous type (n = 14). The first one, with two variants according to its size, macro- (n = 9) and microtumors (n = 3), had predominantly a honey-comb pattern with 'clear halos' around the nuclei without anaplasia. The second type, composed mostly by macrotumours, was anaplastic, with high cellular density, necrosis and intratumoral hemorrhages. Peanut agglutinin (PNA) labelled plasma membranes of well-differentiated cellular components of the first group. The tumoral oligodendrocytes lost the property to bind PNA in the second group of tumours, while Concanavalin A (Con A) showed affinity to intracytoplasmic structures of these tumours. PNA is a reliable marker of oligodendroglial plasma membrane of well-differentiated ENU-induced oligodendrogliomas. This experimental model, using PNA and Con A, may have important clinical applications regarding the biological behaviour of this type of neoplasm.

Cellular uptake of magnetic fluid particles and their effects on human adenocarcinoma cells exposed to AC magnetic fields in vitro

Suspensions of coated superparamagnetic particles (magnetic fluids, MF) in AC magnetic fields have a pronounced specific absorption rate (SAR) per mass compared to multidomain particles. The aim of the present study was to investigate cellular uptake and the biological effects of AC magnetic field excited bio-compatible magnetic fluids on human carcinoma cells in vitro. One of the fluids tested was a dextran magnetite, which has a very low cyto-toxicity with survival fractions (SF) between 0.8 and 0.9 at concentrations of up to 5 mg ferrite per ml. Human carcinoma cells intracellularly accumulate up to 1 pg ferrite/cell which has been demonstrated by electron microscopy (TEM), X-ray spectroscopy and measurements of intracellular iron. It has been shown that the ferrite core is not altered intracellularly, but many of the dextran shells are degraded which yields particle chains and other aggregates observed in TEM. Semi-solid pellets of the tumour cells were treated with AC magnetic fields (520 kHz, 4-12.5 kA/m) or waterbath hyperthermia at 43 and 45 degrees C, in presence of extracellular and/or intracellular magnetic fluid particles. Although MF heating is produced from individual particles, the survival fractions of MF heated and water bath heated cells are equal. In fact, the extracellular MF particle distribution is homogeneous enough to obtain similar inactivation. In contrast to earlier reports intracellular dextran magnetite particles in AC magnetic fields did not induce cell inactivation. Since the amount of intracellular ferrite should be indeed large enough for cell inactivation, the loss of dextran shells is most probably the main cause of limited effectiveness of the intracellular magnetite particles. The present work has demonstrated that: (1) MFH is able to inactivate tumour cells in vitro to at least the same extent as water bath hyperthermia; and (2) that there is a sensitizer effect of ferrofluids at 43 degrees C probably caused by free ferric ions which induce oxidative stress; and (3) that there is no cytotoxic effect of intracellular dextran magnetite particles 30-180 min excited with AC magnetic fields used in this study. For the new method the term 'magnetic fluid hyperthermia (MFH)' is proposed.

Clear cell meningioma: report of a spinal case

A sacrococcygeal case of clear cell meningioma in a 38-year-old man is reported. Compared to the seven spinal clear cell meningiomas described so far, this case demonstrated the highest recurrency rate. Multiple recurrences were most likely due to the extensive infiltrative growth pattern of the tumor hindering complete microscopic surgical resection. Histologic parameters were not relevant to predict recurrences, since cellular anaplasia was lacking and growth fraction was low in the first operation and all subsequent recurrences. In view of what is now known of clear cell meningiomas, the tumor showed all histologic and immunohistochemical features which are typical for this tumor entity. However, the tumor was first diagnosed by capable pathologists and neuropathologists as fibroma-like mesenchymal tumor, metastatic renal carcinoma, chordoma, chondroma untypical osteosarcoma, and microcystic meningioma. Correct diagnosis was made by electron microscopy which has revealed comparable findings to those of other rare electron microscopical cases reported so far; high content of cytoplasmic glycogen diffusely distributed throughout the cytoplasm or aggregated within vacuoles, intermediate filaments, desmosomes, interdigitation of cell membranes and large amounts of collagen fibers, some of which were of the giant amianthoid type. Since meningiomatous features of clear cell meningiomas are not obvious light microscopically and the tumors may be confused with nonmeningiomatous neoplasms, electron microscopical investigation is highly recommended in each case of suspected clear cell meningioma.

Neuron-like physiological properties of cells from human oligodendroglial tumors

One of the most common symptoms of patients with oligodendrogliomas is the high frequency of epileptic seizures. We thus studied the physiological properties of cells in six human oligodendrogliomas and two oligoastrocytomas obtained from surgical material. The majority of tumor cells in living brain slices can generate action potentials as recorded with the patch-clamp technique indicating that this tissue is dominated by electrically excitable cells. In cultures from the same material, the action potential generating cells prevail within the first days and are subsequently replaced by electrically inexcitable cells. From histopathological and immunohistochemical data, the histogenesis of human oligodendroglial tumor is still uncertain. Our physiological study has not settled the debate on the origin of these tumors but revealed important findings with regard to this question. Since action potential generating glial cells have not been described in situ so far their occurrence in oligodendroglial tumors implies that oligodendroglial tumor cells may belong to the neuronal cell lineage.

Human central neurocytoma cells show neuronal physiological properties in vitro

Central neurocytoma is a rare brain tumor composed of small round synaptophysin-positive cells, suggesting a neuronal origin of these tumor cells. Glial properties are inferred, however, from the observation that the tumor cells exhibit a strong morphological similarity to oligodendroglioma cells and show an astrocytic differentiation in vitro. To test for neuronal or glial physiological properties, we studied cultured neurocytoma cells derived from a surgical specimen from a 44-year-old man, employing the patch-clamp technique. Early primary cultures were composed of morphologically unique bi- or multipolar cells which were positive for synaptophysin and negative for the astrocyte marker glial fibrillary acidic protein. In the majority of these cells, whole-cell membrane current recordings revealed physiological properties of neurons, i.e., a high density of Na+ currents, the capacity to generate action potentials, and the expression of inotropic neurotransmitter receptors. Metabotropic neurotransmitter receptors could be demonstrated by Ca2+ imaging techniques. The remaining bi- or multipolar cells and almost all cells in later culture stages and in vitro passage lacked these neuronal properties and showed physiological features characteristic of glial cells. We conclude that the major population of neurocytoma cells shows physiological properties of neurons and that with time in culture this population is replaced by electrically passive cells.

[The structure of the stellate sympathetic ganglia under long-term hypoxia]

Changes of mitochondrial ultrastructure indicating not only degenerative processes but also the presence of organelle adaptive reactions were demonstrated in sympathetic neurons. Appearance of osmiophilic inclusions in mitochondrial matrix relates to most typical organelle alterations in ageing. Number of smooth endoplasmic reticulum vesicles equal in size to synaptic vesicles of nerve cells processes grows higher. Such vesicles are usually located near postsynaptic active zones and areas with neuronal plasmolemma free from glia. Their outward resemblance does not allow to claim that neuromediators and neuromodulators may turn up in these vesicles, although dendrites contain and may release certain biologically active substances. Basic difference between 24 and 30-months old rats lies in earlier degenerations of nerve cells in old animals. Forming of dark granules may be also associated with conditions of fixation. Small granular (SG) cells lacked typical lipofuscine granules, while their ultrastructure changed insignificantly. SG cells capacity to divide mitotically in functional maturity is likely to be one of the possible explanations of such difference.

Ischemic stress induces deposition of amyloid beta immunoreactivity in human brain

The histoblot immunostaining technique for locating and characterizing amyloidogenic proteins was used to obtain information about the relationship of cerebral ischemia/hypoxia to the accumulation of amyloid beta protein (A beta). We investigated brains of 131 subjects (ages 25-94 years, mean 72 years). Three distribution patterns of A beta immunoreactivity were identified: (1) colocalization with diffuse and neuritic plaques of Alzheimer's disease (AD) and aging; (2) diffuse punctuate deposits in the cerebral cortex in association with small vessel cerebral vascular disease ; and (3) cerebral cortical accumulation localized to arterial boundary zones and other regions susceptible to ischemic/hypoxic injury designated "stress-induced deposits" (SID). SID were not identified in tissue sections by immunohistochemical, Congo red or Bielschowsky silver techniques; no histological abnormalities were present in adjacent formalin-fixed tissue sections, SID occurred in subjects with histories of cerebral ischemia, and severe orthostatic hypotension. There was also an association with aging in general and with the incidence of neuritic plaques specifically. These latter findings are consistent with the hypothesis that brain ischemia/hypoxia plays a role in the pathogenesis of AD.

The neuropathology and epidemiology of AIDS. A Berlin experience. A review of 200 cases

The brains of 200 patients who died with Acquired Immunodeficiency Syndrome (AIDS) from Berlin were examined retrospectively. This study was specifically intended to evaluate and document the prevalence of neuropathologic abnormalities, establishing the frequency of the various types of structural lesions, their combinations, their relative incidence, and the risk factors involved in different age groups. The data were compared and contrasted with the findings reported from other parts of the world and other German cities. It was found that the mean age of this group of patients was 41.4 years old, 75% were homosexual/bisexuals (H/B) and 18.5% were drug abusers (DA). Only 5.5% were women. Brain parenchymal changes, called in this report, HIV-related encephalopathy (HIVRE), characterized by vacuolization or spongy changes and astrocytosis in the subcortical white matter, and occasionally in gray matter, were found in 67 patients (33.5%). Drug abusers had a higher incidence of HIVRE (59.5%) compared with homosexual/bisexuals (28%). This is statistically significant (p < 0.0005). CMV encephalitis was found in 26 patients (13%) (8% of the drug abusers in contrast to 13% in the homosexual/bisexuals group). Primary central nervous system lymphoma (PCNSL) was seen in 28 patients (14%) regardless of the risk factor involved. 20 (13%) of the 150 H/B and 3 (8%) of the 37 DA had CMV encephalitis. Of the 150 H/B, 24 (16%) had PCNSL compared with only 4 of 37 (11%) of the DA. A significant incidence of opportunistic infections, both protozoal and viral was found in all groups. Cerebral toxoplasmosis occurred in 68 patients (34%). Microglial (phagocytic) nodules, probably related to CMV or cerebral Toxoplasmosis, were observed in 40 cases (20%). Diffuse microglial proliferation was noted in 104 patients (52%). Cerebral cryptococcosis was found in three patients. Progressive multifocal leukoencephalopathy was seen in 16 patients (8%). Various combinations of CNS pathological processes were found in 44 of the patients (22%). These include concomitant infections with Toxoplasma gondii and HIVRE in 13 patients; Toxoplasmosis and PCNSL in 8 patients; Toxoplasmosis with CMV and HIVRE in 4 patients; Toxoplasmosis with CMV in 2 patients; Toxoplasmosis with PCNSL and CMV in 2 patients; Toxoplasmosis with PCNSL and HIVRE in 2 patients and Toxoplasmosis with PML and HIVRE in 2 patients; Cerebral CMV with PCNSL and HIVRE in 4 patients; Cerebral CMV with HIVRE in 2 patients; PML with PCNSL in one patient; PML with HIVRE in 2 patients; and PML with PCNSL and HIVRE in one patient. Cerebrovascular lesions were found in 34 patients (17%).(ABSTRACT TRUNCATED AT 400 WORDS)

Ultrastructural morphology of the aged pineal

Thirty-four pineals of 18-month-old rats were studied, of which 12 belonged to animals exposed to 7% and 13 to a group exposed to 10% oxygen in breathing gas. Nine pineals were from controls kept under normoxic conditions. For comparison 2 pineals of 6-week-old rats were also examined. No influence of hypoxia on histology of the pineal gland can be stated. In this the pineal behaves like other parts of the rat brain, which in previous experiments has been shown to adapt well to low-oxygen concentrations. Also no important difference between pineals of young and advanced aged rats were found by us. In 8 of 34 pineals striated muscle cells were present. We consider this an important finding, as pineal cells have a unique differentiation potential in cell culture systems and in tumorous lesions of the pineal. As rats exposed to severe hypoxia exhibit body organ changes indicating stress, it would be interesting to measure melatonin secretion and pineal melatonin content under prolonged and increasing hypoxic conditions.

[Intraspinal neurinoma in the thoracolumbar junction presenting unusual symptoms. The differential diagnosis of lumbago]

After more than a year of persistent lumbosacral pain a 53-year-old woman suddenly developed unilateral monoradicular pain over the S1 dermatome. Neurological, general medical and biochemical examinations were unremarkable, but myelography and magnetic resonance imaging revealed a cystic intraspinal space-occupying lesion at the level of L1, which was completely excised surgically. It proved to be a neurinoma, 5 x 3 x 3 cm, completely filling the spinal canal at the junction between the conus medullaris and the cauda equinus. The patient was without symptoms and neurological deficit after the operation. The tumour having been completely removed, the prognosis is good.

Neuropathological changes following occlusion of the superior sagittal sinus and cerebral veins in the cat

Superior sagittal sinuses (SSS) of 36 mongrel cats were occluded by polymer injection. Immediately prior to the occlusion, Evans-blue (EB) was administered intravenously. The cats were killed 1,3,6,12,24,72 and 120 h after sinus occlusion. Two sham-operated cats were killed 6 h and two 120 h after the operation. In 16 cats in which the occlusion was limited to the SSS, as well as in the sham-operated cats, no EB extravasation was present. However, ultrastructurally in two animals, the extracellular spaces were moderately enlarged, corresponding to increased permeability for water without opening of the BBB for proteins. In 20 cats in which cortical veins were occluded, in addition to the SSS, EB was extravasated. In nine of these cats, which had moderate oedema, EB-staining was present only in the cortex. In 11 cats with severe oedema, massive EB was extravasated. In nine of these cats, which had moderate oedema, EB-staining was present only in the cortex. In 11 cats with severe oedema, massive EB extravasation was observed also in the white matter. The U-fibre layer was free of EB, suggesting that the extension of oedema was blocked by this zone. Cats with severe oedema showed extensive haemorrhagic cerebral infarction widely, but not completely, overlapping with ischaemic necrosis, and corresponding to the differences in the territories of arterial supply and of venous drainage. Seven animals displayed haematomas in the parasagittal white matter. Electron microscopy (EM) showed damage to the endothelium of capillaries and venules with extravasation of platelets. In cats which survived longer than 24 h, the extracellular spaces were filled with proteinaceous transudate.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of BBB damage in an UV irradiation model by endogenous protein tracers

Autologous serum proteins have proved to be suitable tracer to evaluate vascular permeability. The dynamic behaviour of anti-HRP immunoglobulins was studied in ultraviolet (UV) irradiation induced brain edema. Cerebral cortex of 36 anaesthetized adult rats was irradiated following a 2 x 2 mm parietal craniotomy. Immunization was carried out by 3 subcutaneous injections of 10 mg HRP in 0.5 ml complete freund adjuvant (CFA), 6, 4 and 2 weeks before the injury. Control animals were immunized only with CFA; further control animals were operated and irradiated without any previous immunization. After survival times ranging from 30 min to 24 hours, postoperation animals were transcardially perfused with 4% fresh paraformaldehyde solution in phosphate buffered saline. After postfixation at 4 degrees C, 20 microns vibratome sections were prepared for incubation with a solution of 0.05% HRP, washed and developed by the DAB reaction. The reactions showed a remarkable exsudation and spreading of anti-HRP antibodies in the edematous brain. The antigen-antibody reaction was conspicuous in animals with shorter survival periods in the necrotic area and near the lesion (1-2 mm). After a longer survival time extravasation involved the whole hemisphere. In animals with the longest survival period labeled serum proteins were found even in the white matter of the hemisphere contralateral to the injury. Endogenous tracer of BBB function is useful to study the spreading of brain edema in a delayed time after the edematous lesion.

Morphology of non-vascular intracerebral fluid spaces

In the electron microscope the value for the extracellular space (ECS) in the mammalian CNS was suggested of several percent to about one third dependent on the method how it was evaluated. Since von Harreveld introduced 1965 cryofixation to estimate the extension of the ECS, the method has been never applied in brain edema research. We carried out improved low temperature methods to measure the extracellular space of the mammalian CNS in physiological conditions. Small samples of brain tissue were cryofixed by slam freezing on a precooled metal mirror and substituted with ethanol at -95 degrees C over 17 hours. The embedding procedure was carried out at -22 degrees C with LR-White under UV-irradiation. ECS was measured computer assisted with Bioquant Software. The values for the ECS of the cryofixed normal rat brain were more than twice compared to the usual transmission electron microscopy (16.3% to 7.4%, p < 0.01) and close to those estimated by von Harreveld (18.1-25.5%, 1965). It was interesting that the data obtained in cryofixed normal rat brain correspond to the extension measured in rat brain with irradiation edema, which was conventionally treated for EM. Greater variance of ECS in cryofixed brain (16.3% +/- 3.4) demonstrate that it is far more variable than expected. This data correspond closely to the in vivo ECS. The morphological evaluation of brain edema should be revised under this premise.

Subcortical U-fibers layer preservation in brain edema

The mechanism involved in the relative preservation of the subcortical U-fibers in the arcuate zone was studied in a post infarct edema after sagittal superior sinus occlusion. Superior sagittal sinus (SSS) of 36 mongrel cats were occluded by polymer injection. Immediately before the occlusion Evans-blue (EB) was administered intravenously. The cats were killed 1, 2, 3, 6, 12, 24, 72 and 120 hours after sinus occlusion. In 20 cats in which cortical veins were occluded, in addition to the SSS, EB was extravasated. In 9 of these cats, which had moderate edema, EB-staining was present only in the cortex. In 11 cats with severe edema, massive EB extravasation was observed also in the white matter. The U-fiber layer was free of EB, suggesting that the extension of edema was blocked by this zone. Our findings demonstrated that the U-fibers act not only as a resistance against extension of edema from white to gray matter, but also in a reverse direction. The characteristics of the spread of brain edema is not yet completely understood; both anatomical and biochemical peculiarities from its basis. Different morphological patterns in the astrocytic reaction as well as the U-fibers sector vascularization are important. To evaluate the role of each one of these factors in the preservation of subcortical U-fiber layer in brain edema further investigations should be done.

Neurofibrillary pathology in progressive supranuclear palsy (PSP)

In progressive supranuclear palsy (PSP), globose neurofibrillary tangles (NFT) are found in the subcortical areas and occasionally in the central cortex and spinal cord. An inverse relationship was found between the degree of neuronal loss and the presence of NFT. It has been postulated that NFT comes first and atrophy as a secondary event. Others authors have reported that the neurologic findings are associated with the presence of carcinomas and the CNS changes can be assessed as a paraneoplastic effect. In PSP the neuritic changes are mainly located in the basal ganglia and composed of straight filaments and tubules, different from the paired helical filaments found in the Alzheimer's disease, suggesting that they are formed of a new type of fibrous protein. In addition immunohistochemistry preparations using antibodies against tau and ubiquitin reveal an antigenic profile similar to early NFT in dementia of Alzheimer's type. These findings support the hypothesis that these changes may reflect different types of non-specific cytoskeletal disorganization.

p-Chlorophenylalanine, a serotonin synthesis inhibitor, reduces the response of glial fibrillary acidic protein induced by trauma to the spinal cord. An immunohistochemical investigation in the rat

The possibility that serotonin may influence the early response of astrocytes around a spinal cord trauma was investigated in a rat model by making a unilateral incision into the right dorsal horn of the T10-11 segments. One group of rats received a serotonin synthesis inhibitor, p-chlorophenylalanine (p-CPA) before injury in doses which cause a depletion of serotonin in the cord. Another group of traumatised rats did not receive p-CPA. All animals were allowed to survive for 5 h. Samples for immunohistochemistry were taken from the T9, T10-11 and T12 segments of the cord. Paraffin sections were immunostained for glial fibrillary acidic protein (GFAP) using monoclonal antibodies and avidin-biotin complex technique. Trauma to the cord resulted in a marked increase of GFAP immunoreactivity in all the investigated segments, particularly in the ipsilateral side. Pretreatment with p-CPA markedly reduced the GFAP response. This drug did not by itself influence the GFAP immunoreactivity of the cord of untraumatised rats. Our results show that trauma to the spinal cord induces a rapid enhancement of GFAP immunoreactivity in the cord which is present even far away from the primary lesion. This response can be prevented by pretreatment with the serotonin synthesis inhibitor, p-CPA. The results indicate that serotonin influences the increase of GFAP immunoreactivity following spinal cord injury either directly or indirectly, for instance by its microvascular reactions.

Dysembryoplastic neuroepithelial micro-tumor in a 75-year-old patient with long-standing epilepsy

Dysembryoplastic neuroepithelial tumors (DNT) are rare, cortically located neoplasma associated with intractable partial complex seizures. This entity was first described by Daumas-Duport et al. [1988], who also coined the term DNT. In that report, at the time of operation, the patients' ages ranged from 3 to 30 years and the duration of symptoms ranged from 2 to 18 years. In contrast, we observed a histologically comparable tumor in a 75-year-old female with a 60 year epilepsy history. Autopsy revealed an 8 mm large tumor in the right hippocampus. In view of the extremely prolonged course of the patient's symptoms and the complete lack of excessive cell proliferation, the differentiation of a genuine tumor versus a hamartoma remains equivocal.

Microthrombi formation after severe head trauma

This study was undertaken to look for trauma-related fibrinous microthrombi in traumatized human brains. Fifty brains from patients with variable time intervals between trauma and death were fixed in 10% formaldehyde. Sections from the contusioned area and from the corresponding area of the contralateral hemisphere were embedded in paraffin and 50 non-traumatized brains were used as controls. After sectioning and embedding, 10 microns sections were stained with haemalum and eosin (HE) and phosphotungstic acid-hematoxylin (PTAH). Stained fibrinous microthrombi were counted in each hemisphere and in control sections. More microthrombi could be found in the contusioned areas of the brain than in the contralateral side or in control sections.

Pathological changes in organs of rats chronically exposed to hypoxia. Development of pulmonary lipidosis

Rats were exposed to chronic normobaric hypoxia of progressively increasing severity; down to 8% or 7% oxygen concentrations. In addition to loss of weight, pathology revealed congestion, haemorrhages, hypertrophy of the heart involving mainly the right ventricle, thickening of arteries, ischaemic changes in the myocardium and extramedullary haematopoiesis in the spleen. Changes not described up until now were: 1) sheets of foam cells in the pulmonary alveoli; 2) foamy and solid storing cells in the spleen; 3) mucoid changes in the atrioventricular valve leaflets; 4) hyperplasia of the juxtaglomerular apparatus; 5) atrophy of the adrenal glomerulosa and hyperplasia of medulla; 6) atrophy of the perifollicular B-cell zone in the spleen; and 7) lipid pigment deposition in various organs. The findings indicate that severe chronic hypoxia induces a significant pulmonary lipidosis similar to that caused by amphiphilic cationic drugs, presumably by inhibiting hydrolytic enzyme activities. The observations are of importance in human hypoxic conditions and open the possibility of their rational treatment.

HEA 125 and Ber EP4: two monoclonal anti-epithelial, non-cytokeratin antibodies distinguishing metastatic carcinomas from glial tumors

Since some monoclonal anti-cytokeratin antibodies also react with glial tumors to a relatively high degree, an immunohistochemical study was performed to examine the reaction of 40 glial tumors and neuroepithelial tumors with glial differentiation to the monoclonal anti-epithelial non-cytokeratin antibodies HEA 125 and Ber EP4. Seven of these tumors were cytokeratin-positive neoplasms (6 gliosarcomas and 1 ependymoma). In addition, 20 metastatic carcinomas were investigated. All glial tumors showed a negative reaction to HEA 125 and Ber EP4, whereas 19 of the 20 metastatic carcinomas were positive with these two monoclonal antibodies. HEA 125 and Ber EP4 thus can be used as additional markers especially in cytokeratin-negative small cell carcinomas.

Degenerative changes in the internal elastic lamina relating to the development of saccular cerebral aneurysms in rats

In order to investigate the developmental mechanism of saccular cerebral aneurysms, changes in the internal elastic lamina at the junction of the anterior cerebral artery and the olfactory artery were electronmicroscopically studied in 6 control and 6 experimental rats undergoing ligation of the left carotid artery and branches of both renal arteries. In the control group, spontaneous destructive changes occurred on the luminal side of the internal elastic lamina and progressed from the luminal towards the abluminal side as the elastic lamina advanced to the apex. Close to the apex, these changes invaded and disrupted the whole elastic lamina. The elastic lamina was replaced by sparsely lined up lumps of elastic tissue in the walls of early aneurysmal alterations, and was atrophied and disappeared totally in the walls of aneurysmal alterations that had reached an advanced stage. These spontaneous changes were in agreement with reports in the literature and our own previous investigations. From the findings in the experimental rats it becomes likely that the aneurysmal changes in the elastic lamina are exaggerated forms of the normal catabolic metabolism. Therefore its synthesis on the abluminal side no longer balances with the catabolism on the luminal side. It is strongly suggested that aneurysmal alterations progress from the luminal towards the abluminal side of arterial walls and that the lytic process of elastase might play a role in the degenerative changes in aneurysmal development.

Central nervous system alterations in a case of short-rib polydactyly syndrome, Majewski type

The authors present a case of CNS abnormalities in a female newborn infant with Majewski syndrome. On examination the gyri were found to be normal, but there was narrowing of the corpus callosum and fornix, and dilated ventricles. A vermis hypoplasia and an arachnoid cyst were found between the cerebellar hemispheres. Cross-section of the cervical and thoracic segments revealed a flattened spinal cord in the sagittal section. There were reactive astrocytes and heterotopic ganglion cells in the white matter and isolated hypoxically damaged nerve-cells in the subiculum and nuclear masses of the brainstem. These findings are discussed with reference to the literature.

Early perifocal cell changes and edema in traumatic injury of the spinal cord are reduced by indomethacin, an inhibitor of prostaglandin synthesis. Experimental study in the rat

The possibility that prostaglandins participate in the formation of perifocal edema and cell changes following a localized trauma to the spinal cord was investigated in a rat model. A laminectomy was performed in urethane-anesthetized animals at the thoracic T10-11 segment. Using a scalpel blade a unilateral lesion, about 2 mm deep and 5 mm long was made 1 mm to the right of the midline. The deepest part of the injury occupied Rexed's lamina VII of the dorsal horn. Animals were pretreated with the prostaglandin synthesis inhibitor, indomethacin (10 mg/kg, i.p. 30 min prior to trauma). Five hours after the injury the water content was determined and cell changes in and around the primary lesion were examined by light and electron microscopy. Normal and injured rats without indomethacin pretreatment served as controls. Untreated injured rats showed a profound increase of water content in the traumatized T10-11, the rostral (T9) and caudal (T12) segments compared with normal rats. These segments also exhibited marked cell changes in ipsilateral and contralateral dorsal and ventral horns. The gray matter had a spongy appearance and some nerve cells were condensed and distorted. The white matter contained many distorted fibers. Immunostaining for myelin basic protein showed a marked reduction of reaction product in the injured animals compared with normal rats. Ultrastructurally widened extracellular spaces, cytoplasmic vacuolation, swollen and condensed neurons, swollen astrocytes and vesiculation of myelin were frequent findings. Pretreatment of rats with indomethacin significantly reduced the accumulation of water in the traumatized and in the rostral and caudal segments. The structural changes were less pronounced particularly in the cranial and caudal segments.(ABSTRACT TRUNCATED AT 250 WORDS)

Alterations in cerebral vessels in experimental animals and their possible relationship to the development of aneurysms

Aneurysmal changes were studied by light and electron microscopes in experimental monkeys to elucidate their pathogenesis. Early changes were found not at the medial defect but in one branch near the apex. Degeneration of the elastic lamina was always more than that of the media throughout the process of aneurysm formation. Endothelial injury was present even at the bifurcation without a bulge. The present study suggests that aneurysmal changes are initiated by degenerative changes in the endothelium, which are followed by alterations in the underlying elastic lamina and, in turn, in the medial layer.

Influence of preoperative dexamethasone therapy on proliferating cell nuclear antigen (PCNA) expression in comparison to other parameters in meningiomas

We conducted a trial in 42 benign and malignant meningiomas to assess a possible influence of preoperative dexamethasone therapy on mitotic index, labelling indices of proliferating cell nuclear antigen (PCNA), progesterone receptor, epidermal growth factor receptor (EGF-R), c-erbB-2 oncoprotein, cathepsin D, gamma-gamma enolase as well as the mean number of silver-stained nucleolar organizer region-associated proteins (AgNORs). Tumors with preceding dexamethasone therapy for more than 1 day display significantly less immunohistochemical staining for PCNA. A correlation between the labelling index of PCNA and the degree of malignancy could not be identified. There was no significant effect of preoperative dexamethasone therapy on the other parameters. Our data suggest that dexamethasone may selectively inhibit the expression of PCNA in the G1/S-phase of the cell cycle. Thus, we emphasize the necessity to heed factors, e.g. dexamethasone, which may affect the expression of proliferating markers.

Role of serotonin in heat adaptation: an experimental study in the conscious young rat

The possibility that serotonin may play a role in heat adaptation was examined in a rat model of heat stress (HS). Subjection of animals to acute 4 h HS (but not to 1 h and 2 h duration) in a biological oxygen demand (BOD) incubator (relative humidity 50-55%, wind velocity 20-25 cm/s) resulted in profound hyperthermia (41.68 +/- 0.25 degrees C) associated with behavioural salivation and prostration. This experimental condition simulates the out door environmental conditions of Varanasi, India during the month of June. Measurement of serotonin (5-hydroxytryptamine, 5-HT) content in the plasma and brain showed a profound increase of the amine by 462% and 187% respectively from the control group. Morphological examination in these animals revealed marked cell changes in the brain at both light and electron microscopic level. Thus chromatolysis, shrunken and dark neurons along with a general sponginess of the gray and white matter was quite frequent in all the brain regions. At ultrastructural level, perivascular edema, damage to pre- and postsynaptic terminals, swollen neurons and glial cells, splitting of myelin and vacuolation was very common throughout the whole brain. The microvessels were mainly collapsed and a diffuse infiltration of lanthanum ion within the endothelium was common. Occasionally, lanthanum could also be seen within the basement membrane. However, the tight junctions were mainly intact. On the other hand, when animals exposed to chronic heat stress of 1 h duration at the same intensity for 7 days and then subjected to a 4 h HS on the 8th day, resulted in only minor symptoms. Thus these 4 h heat stressed animals did not exhibit hyperthermia or increased serotonin levels in plasma and brain as compared to the animals exposed to chronic HS of 1 h duration until alone 7th day. These heat adapted animals did not show any marked cell changes in the brain. However, the values of circulating 5-HT level and rectal temperature of these chronically heat stressed animals (for 1 h daily) were mild but significantly elevated on the 7th day as compared to the intact control animals. These results show that: 1. chronic HS of short duration induces heat tolerance; 2. the circulating 5-HT level some how appears to play an important role in the pathophysiology of HS; hand in the physiological mechanism(s) of secondary heat adaptation.

Enhancement of nerve fibre regeneration by nucleotides after peripheral nerve crush damage. Electrophysiologic and morphometric investigations

The effect of nucleotide administration on the regeneration of myelinated nerve fibres following crush injury to the sciatic nerve of the rat was studied using both morphometric and electroneurophysiologic techniques. After a standardized localized crush lesion of the right sciatic nerve, rats were given nucleotides daily at a dosage of 3.0 mg/kg body wt uridine monophosphate (UMP), 2.5 mg/kg body wt cytidine monophosphate (CMP) or 3.0 plus 2.5 mg/kg body wt UMP plus CMP, respectively. Observations were made after 20, 40 and 60 days of nerve regeneration for comparison with age-matched crushed or nonoperated controls. Electroneurophysiologic studies of right sural nerves were performed as single fibre measurements. Morphometry was performed on semithin transverse sections of the right common peroneal nerve with a fully automatic interactive image analysis system. Forty days after crush injury the single fibre conduction velocity of all type II afferents in the UMP/CMP treated group was significantly accelerated. There was a trend (10% greater than or equal to p greater than or equal to 5%) to increase of mean efferent single nerve fibre function at this time. Morphometry of nerve fibres revealed a trend to enlargement of mean fibre area and mean fibre diameter related to increased myelin area and myelin thickness. After 60 days, there was a trend to increase of single fibre conduction velocity of all type II afferents in the UMP/CMP treated group. Automated morphometry revealed a significant increase for the following parameters: fibre area, fibre diameter, myelin area, myelin thickness and axon area.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo study of flow pattern at human carotid bifurcation with regard to aneurysm development

In order to investigate the developmental mechanism of cerebral aneurysms, the in vivo flow pattern around human cervical carotid bifurcations was studied by flow visualization using digital subtraction angiography with an isotonic contrast medium. The blood stream containing the medium impinged on the apex, then proceeded along the walls of the branches. After opacification of the whole lumen around the apex, most of the medium was carried away, while some remained for a few seconds at the carotid sinus. In the internal carotid artery, the blood struck the wall at an oblique angle near the tops of the arterial curvatures. In cases with atheromatous plaque or kinking of the branch, the blood passed through the stenosed segment and moved upstream, indicating turbulence. The study suggests that haemodynamic forces around the apex consist mainly of impingement on the apex and shear stress to the wall at and around the apex. In branches, high shear stress seems to exist. It might be possible that high shear stress causes degenerative changes in the endothelial layer, initiating the formation of saccular and fusiform cerebral aneurysms.

Acute systemic heat stress increases glial fibrillary acidic protein immunoreactivity in brain: experimental observations in conscious normotensive young rats

The possibility that astrocytes participate in the pathophysiology of thermal brain injury caused by systemic heat exposure was examined in conscious young rats. The temporal and regional pattern of the astrocytic response to thermal injury was characterized by demonstrating the immunoreactivity of glial fibrillary acidic protein (GFAP) using monoclonal antibody and avidin-biotin complex technique. Exposure of conscious young animals to heat at 38 degrees C for 4 h in a biological oxygen demand incubator resulted in a marked increase of the GFAP immunoreactivity in specific brain regions as compared with the intact controls. The intensity of the increased GFAP immunoreactivity was mainly noted in pons, medulla and cerebellum, followed by thalamus, hypothalamus, hippocampus and caudate nucleus. The cerebral cortex of heat-exposed animals showed only a mild increase in GFAP immunoreactivity which was predominantly concentrated in cingulate, parietal and pyriform cortices. The immunostaining in general was seen in the perivascular glia, within the neuropil and the glia limitans. This increase in GFAP immunoreactivity was absent in animals exposed to the same ambient temperature (38 degrees C) for 1 h and 2 h, or at a lower temperature (36 degrees C) for 4 h. These results show that (i) astrocytes actively participate in the pathophysiology of heat stress, (ii) endogenous thermal brain injury elicits activation and hypertrophy of astrocytes ("reactive gliosis") depending on the magnitude and duration of the ambient heat stimulus, and (iii) the astrocytic reaction (observed as increased GFAP immunostaining) could be induced much more rapidly within a very short survival period of 4 h, not reported earlier.