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DHEA, together with DHEAS, is the most abundant steroid in the blood of young adult humans. Levels in humans decline with age and during certain types of illness or stress. We have found that DHEA(S) can prevent or reduce the neurotoxic actions in the hippocampus of the glutamate agonists N-methyl-D-aspartic acid (NMDA) both in vitro and in vivo or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainic acid in vitro. Pre-treatment with DHEA (10-100 nM for 6-8 h) protected primary hippocampal cultures from embryonic day 18 (E18) embryos against NMDA-induced toxicity (0.1, 1, 10, and 50 mM). DHEA added either with NMDA (1 mM) or 1 h later had lesser, but still significant, protective actions. DHEAS also reduced NMDA-induced toxicity (1 mM), although the lowest effective dose of DHEAS (100 nM) was higher than that of DHEA (10 nM). DHEA (100 nM) protected cultured neurons against the neurotoxic actions of either AMPA (25 microM) or kainic acid (1 mM) as well. In vivo, s.c. pellets of DHEA, which resulted in plasma levels that resembled those in young adult humans, protected hippocampal CA1/2 neurons against unilateral infusions of 5 or 10 nmol of NMDA. Because the release of glutamate has been implicated in the neural damage after cerebral ischemia and other neural insults, these results suggest that decreased DHEA levels may contribute significantly to the increased vulnerability of the aging or stressed human brain to such damage.

Progenitor cells were isolated from the developing human central nervous system (CNS), induced to divide using a combination of epidermal growth factor and fibroblast growth factor-2, and then transplanted into the striatum of adult rats with unilateral dopaminergic lesions. Large grafts were found at 2 weeks survival which contained many undifferentiated cells, some of which were migrating into the host striatum. However, by 20 weeks survival, only a thin strip of cells remained at the graft core while a large number of migrating astrocytes labeled with a human-specific antibody could be seen throughout the striatum. Fully differentiated graft-derived neurons, also labeled with a human-specific antibody, were seen close to the transplant site in some animals. A number of these neurons expressed tyrosine hydroxylase and were sufficient to partially ameliorate lesion-induced behavioral deficits in two animals. These results show that expanded populations of human CNS progenitor cells maintained in a proliferative state in culture can migrate and differentiate into both neurons and astrocytes following intracerebral grafting. As such these cells may have potential for development as an alternative source of tissue for neural transplantation in degenerative diseases.

Background: Ventricular tachyarrhythmias are the leading cause of death from coronary artery disease. A small percentage of these arrhythmias originate in chronically ischemic myocardium, rather than acutely ischemic myocardium, and can be refractory to medical management. Epicardial mapping and focal cryoablation of foci demonstrating early activation may provide definitive therapy when pharmacologic management fails. We report a series of 42 consecutive patients with refractory ventricular tachycardia (VT) who were treated with open epicardial mapping and focal cryoablation after pharmacologic management failed., Methods: We retrospectively reviewed the records of patients who underwent surgical treatment of malignant VT. For patients not recently seen in the clinic, we conducted telephone interviews. At the time of operation, epicardial mapping was performed to locate foci of early electrical activation. These foci were then cryoablated, using 2-minute applications of liquid nitrogen-cooled probes. All patients underwent postoperative electrophysiologic studies to test for inducible VT., Results: Of these 42 patients, 34 (81%) were male, 8 (19%) female. Average age was 62.9 +/- 10.6 years; ejection fraction, 0.20 (range, 0.04 to 0.50); and number of foci ablated, 2.1 +/- 1.1 (range, 1 to 6). At the time of cryoablation, all patients underwent additional procedures, including aneurysmectomy, coronary artery bypass, or valve replacement. The 30-day operative mortality was 9.5% (4 of 42). Of the 38 survivors, 36 (94.7%) were clinically free of VT; the remaining 2 had spontaneous or inducible VT., Conclusions: Open cryoablation of foci propagating VT appears to be safe and effective. It may be the most definitive treatment for malignant VT.

Epidermal growth factor (EGF) responsive precursors isolated from the developing mouse striatum could be continually expanded in culture as free-floating spheres of cells for over 50 days. Under identical conditions, EGF-responsive precursors from the developing rat striatum could only be expanded for between 21 and 28 days, after which crisis ensued and there was a reduction in cell number at each passage. The outer regions of 28-day-old rat spheres contained a heterogeneous population of both dividing and dying cells while the cores were full of dying cells, many of which showed features consistent with apoptosis. Fibroblast growth factor-2 (FGF-2) alone did not lead to an expansion in rat striatal precursor cell number under the conditions used here. EGF combined with FGF-2 acted synergistically on cell growth, but did not prevent the final senescence and death of the rat precursors.

In this study we have performed a detailed analysis of EGF-responsive precursors as they develop into neurons and astrocytes using antibodies to nestin, microtubule-associated protein 2 (MAP-2c and MAP-2ab) and glial fibriallary acidic protein (GFAP). Surprisingly, at early time points, most GFAP-positive cells also stained for MAP-2c, and we postulate that this may be a normal stage of astroglial development. At 7 days most of the cells had developed into astrocytes and MAP-2ab-positive cells only represented 5% of the total neuronal population. This study shows that (i) MAP-2c is a marker for early precursors, (ii) the majority of cells developing from. EGF-responsive precursors develop into glia and (iii) only a small population of cells arising from expanded populations of EGF-responsive precursors develop into neurons expressing MAP-2ab. Thus, certain critical signals important for full neuronal differentiation may be missing from this system.

Earthworms Lumbricus rubellus were exposed to a range of increasing soil copper concentrations in a mesocosm experiment for 17, 40, 70, and 110 days, respectively. Neutral-red retention times were measured along with earthworm tissue copper residues and earthworm growth and survival. The neutral-red retention assay demonstrated a clear dose-response threshold preceding a copper exposure value where increased regulatory activity had resulted in the copper bioconcentration factor (BCF) decreasing from 1 to 0.5. Effects on earthworm growth and survival occurred only at soil copper concentrations where the earthworm BCFs were lowered to ca. 0.5. Thus, the position of the neutral-red threshold could potentially make it possible to differentiate between copper exposure and actual toxicity. In terms of field applicability it was demonstrated that natural and seasonal variations in climatic parameters had little or no effect on the neutral-red response. Neutral-red retention assay has a potential role in environmental risk assessment and routine monitoring, as it is likely to provide a sufficiently accurate warning of impending ecological damage at a level below that found to cause actual physiological damage to the earthworms.

A simple earthworm biomarker, neutral-red retention by coelomocyte lysosomes, was measured concurrently with ecological parameters in order to link effects at different levels of biological organization in a laboratory study. Exposure of the earthworm Eisenia andrei to an increasing range of soil copper concentrations in the laboratory indicated a threshold range for the neutral-red assay at soil copper concentrations between 40 and 80 mg Cu kg-1. This threshold coincided with the soil to worm copper bioconcentration factor decreasing from 1 to 0.3 and thus an apparent onset of a copper regulatory mechanism. Effects at the individual and population levels only occurred at soil copper concentrations beyond that of the biomarker threshold. Thus, it was possible to differentiate between exposure and toxicity. It was therefore possible to conclude that the neutral-red assay has great potential and relevance in earthworm ecotoxicity studies. The assay provides an early warning that can be linked directly to important physiological changes that were observed to precede adverse effects on individuals or populations in this laboratory study.

Two groups of rats with unilateral 6OHDA lesions received either intrastriatal suspension grafts of embryonic ventral mesencephalon or sham grafts. Three subgroups of each of these received intrastriatal infusions of 1000 ng or 500 ng glial cell-line derived trophic factor (GDNF) or vehicle alone for 10 consecutive days. There was a highly significant dose-dependent effect of GDNF both on the number of TH-positive cells surviving in the grafts and on the density of fibre outgrowth. All grafted rats showed rapid compensation of amphetamine-induced rotation compared with rats with sham grafts. GDNF may provide a powerful tool to enhance the survival and maturation of dopaminergic neurones within mesencephalic transplants.

During ageing, basal forebrain cholinergic neurons are prone to degeneration for unknown reasons. In this study we morphometrically evaluated the retrograde labelling of basal forebrain neurons obtained after injection of FluoroGold into multiple sites in the cerebral neocortex in aged (24-33 months) as compared with young adult (four to six months) male Sprague-Dawley rats. In addition, we looked for differences in the distribution of degenerative changes in topographic subdivisions of the basal forebrain cholinergic complex of neurons identified by immunohistochemical detection of the cholinergic markers choline acetyltransferase or low-affinity neurotrophin receptor. After injection of FluoroGold into the cerebral neocortex, the number of retrogradely labelled neurons in the horizontal diagonal band/ substantia innominata and basal nucleus was significantly lower in aged rats, by 41% and 48%, respectively. In aged rats injected with FluoroGold as well as in non-injected aged rats, the numbers of neurons immunoreactive for choline acetyltransferase and low-affinity neurotrophin receptor were significantly lower, by 23-27% in the basal forebrain system as a whole, with no significant difference in the degree of decline amongst different subdivisions (i.e. medial septum, diagonal band, substantia innominata and basal nucleus). The ratios of the number of neurons labelled with FluoroGold as compared with the number of neurons immunoreactive for either cholinergic marker were significantly lower in aged rats, by 32-37%, indicating that the decline in the number of neurons retrogradely transporting tracer was greater than the decline in the number of immunoreactive neurons in aged animals. Immunoreactive as well as retrogradely labelled neurons showed a significant shrinkage of cell surface area of 6-13% in different subdivisions of the basal forebrain cholinergic system in aged rats. These findings confirm significant loss and atrophy of basal forebrain cholinergic neurons in aged rats, and demonstrate significantly reduced retrograde labelling of these neurons with fluorescent tracer applied to their target cortex. This reduced retrograde labelling suggests an impairment of either uptake or retrograde transport mechanisms in these neurons in aged rats. Such an impairment may contribute to the degenerative changes of basal forebrain cholinergic neurons observed in ageing and age-related degenerative conditions such as Alzheimer's disease.

Epidermal Growth Factor (EGF)-responsive stem cells isolated from the developing central nervous system (CNS) can be expanded exponentially in culture while retaining the ability to differentiate into neurons and glia. As such, they represent a possible source of tissue for neural transplantation, providing they can survive and mature following grafting into the adult brain. In this study we have shown that purified rat stem cells generated from either the embryonic mesencephalon or the striatum can survive grafting into the striatum of rats with either ibotenic acid or nigrostriatal dopamine lesions. However, transplanted stem cells do not survive as a large mass typical of primary embryonic CNS tissue grafts, but in contrast form thin grafts containing only a small number of surviving cells. There was no extensive migration of transplanted stem cells labeled with either the lac-z gene or bromodeoxyuridine into the host region surrounding the graft, although a small number of labeled cells were seen in the ventral striatum some distance from the site of implantation. Some of these appeared to differentiate into dopamine neurons, particularly when the developing mesencephalon was used as the starting material for generating the stem cells. EGF-responsive stem cells could also be isolated from the mesencephalon of developing human embryos and expanded in culture, but only grew in large numbers when the gestational age of the embryo was greater than 11 weeks. Purified human CNS stem cells were also transplanted into immunosuppressed rats with nigrostriatal lesions and formed thin grafts similar to those seen when using rat stem cells. However, when primary cultures of human mesencephalon were grown with EGF for only 10 days and this mixture of stem cells and primary neural tissue was transplanted into the dopamine-depleted striatum, large well-formed grafts developed. These contained mostly small undifferentiated cells intermixed with a number of well-differentiated TH-positive neurons. These results show that purified populations of rat or human EGF-responsive CNS stem cells do not form large graft masses or migrate extensively into the surrounding host tissues when transplanted into the adult striatum. However, modifications of the growth conditions in vitro may lead to an improvement of their survival in vivo.

It has been previously shown that lesions of the dorsal striatum can disrupt performance on a variety of cognitive tasks related to prefrontal cortex function. In order to extend these studies, we have compared the effects of bilateral striatal lesions on retention of an operant test of short-term memory using a delayed matching to position task. Rats were initially pretrained on the matching task. Then, one group of animals received ibotenic acid lesions in the dorsal striatum and a second group received sham lesions. The striatal lesions induced marked deficits on delayed matching performance when the rats were retested one week following surgery. The delay-independent pattern of deficit observed does not suggest a primary impairment in short-term memory function. The lesion induced deficits were temporary, with recovery seen in the lesion group back to a control level of performance in 2 additional test sessions 5 and 10 weeks post-lesion. A follow up study investigating the time course of the deficit suggests that the recovery seen in performance measures cannot be attributed to the elapse of time per se, but rather is due to re-learning. In addition to the performance deficits in the operant task, the lesioned rats exhibited marked nocturnal locomotor hyperactivity. The results indicate that bilateral striatal lesions induce marked deficits in retention of the delayed matching to position task. They suggest a key role for the neostriatum in the execution of pre-learned responses, but do not exclude the possibility of additional involvement in short-term memory functions under certain testing conditions.

Many growth factors that have effects on neurons are present in the developing and mature central nervous system where their functions are poorly understood. In the peripheral nervous system, target-derived growth factors can regulate the survival of developing afferent neurons. Recent studies suggest that neurotrophins derived from target neurons may also regulate the survival of afferent basal forebrain cholinergic neurons during development of the central nervous system. However, in mature animals, these cholinergic neurons do not appear to require target-derived neuroptrophins for survival. Similar findings have also been reported for dopaminergic neurons of the substantia nigra. Although further studies are required, available experimental evidence suggests that target-derived growth factors may influence neuronal phenotypes such as axonal sprouting or transmitter production instead of survival in mature animals.

It has been previously shown that lesions of the dorsal striatum can disrupt performance on a variety of cognitive tasks related to frontal cortex function. In order to extend these studies, we have investigated the effects of bilateral striatal lesions on the acquisition of an operant test of short term memory in the delayed non-matching to position paradigm. The animals received either ibotenic acid or saline control injections into the dorsal striatum prior to training on the non-matching task. Striatal lesions retarded acquisition of the task, although with further training the lesioned rats achieved a similar level of asymptotic performance to the control animals. The lesioned rats also exhibited marked nocturnal locomotor hyperactivity when tested under conditions of food deprivation, but not when tested satiated. The results indicate that bilateral striatal lesions induce mild deficits in the acquisition of the discrimination rules involved in performance of the delayed non-matching to position task. The present study does not support a role for the neostriatum in the specific mediation of short term memory in a operant DNMTP test.

Previous studies suggest that a population of precursor cells from the developing and adult mouse striatum can be expanded in culture using serum-free, N2-supplemented medium and mitogenic factors such as epidermal growth factor (EGF). Here we show that EGF-responsive precursor cells from embryonic rat striatum and mesencephalon can also be expanded in culture, incorporate bromodeoxy uridine (BrDU) and develop into spheres that either adhere to the surface of the culture dish or float freely in the medium. Addition of B27, a medium supplement that increases neuronal survival in primary CNS cultures, resulted in a tenfold increase in the number of proliferating cells in vitro over the first week. The effects of B27-supplemented medium on precursor cell survival were only seen when primary cultures were used, such that dividing cells grown in B27 for 1 week could then be transferred to either B27 or N2 medium and show similar survival and division rates in response to EGF. After 1, 2 or 4 weeks of growth in B27-supplemented medium, dissociated precursor cells from either striatal or mesencephalic cultures could be differentiated when exposed to a poly-l-lysine-coated substrate in serum and EGF-free medium supplemented with B27. These cells then matured into a mixed culture containing neurons (approximately 35% of cells), astrocytes (approximately 44% of cells), and oligodendrocytes (approximately 10% of cells), based on immunocytochemical staining with microtuble-associated protein (MAP2), glial fibriallary acidic protein and galactocerebrosidase. When whole spheres of precursor cells were allowed to differentiate, every one examined was found to generate neurons, astrocytes and oligodendrocytes in similar proportions.(ABSTRACT TRUNCATED AT 250 WORDS)

Fetal septal neurons were grown in vitro under glass coverslips. This sandwich culture method significantly increased general neuronal survival, reduced glial proliferation, and permitted the removal of serum from the growth medium after 5 d in vitro. Thereafter, a simple, and completely defined, medium was used, and the effects of NGF, NGF withdrawal, and protein synthesis inhibition were examined on septal cholinergic neurons. NGF added to septal cultures at the time of plating resulted in a threefold increase in the number of cholinergic neurons seen at 14 d in vitro but had no effect on the survival of non-cholinergic cells. Cholinergic neurons identified by staining for AChE, ChAT, and p75NGFR could be maintained in serum-free, NGF-supplemented medium for over 40 d. When NGF was removed and NGF antibodies added to 14-d-old cultures, less than 30% of cholinergic neurons survived a further 4 d, but when NGF was similarly withdrawn from 35-d-old cultures, over 75% of cholinergic neurons survived. Reapplication of NGF after 3 but not after 12 or more hours of NGF withdrawal from 14-d-old cultures prevented the death of most cholinergic neurons. When NGF was withdrawn from 14-d-old cultures in the presence of the protein synthesis inhibitor cycloheximide, over 75% of the cholinergic neurons survived. These findings suggest that septal cholinergic neurons are dependent on NGF for survival only during a critical period of development and that growth factor-regulated developmental cell death may occur in CNS neurons by activation of programmed cell death requiring protein synthesis.

The effect of unilateral excitotoxic ablation of hippocampal neurons was investigated on (1) the local production of mRNA for NGF and related neurotrophins, (2) the amount of NGF protein in the septal region, and (3) the viability and appearance of afferent septal cholinergic neurons in adult rats. After near complete ablation of hippocampal neurons, total levels of NGF, brain-derived neurotrophic factor (BDNF), and neurotrophin-3 (NT3) mRNA measured by quantitative Northern blot analysis in the hippocampal remnant fell significantly, to less than 25% of control values by 28 d and to less than 9% by 300 d. In the septal region ipsilateral to such lesions, NGF protein levels measured by ELISA fell significantly, to about 35% of control values, but the number of immunohistochemically detected cholinergic neurons did not decline significantly for up to 500 d. Instead, the cholinergic neurons persisted in an atrophied state, exhibiting severe shrinkage and reduced staining for the transmitter-synthesizing enzyme ChAT. The parameters of cell size and ChAT staining intensity correlated significantly with the amount of hippocampal tissue present. These findings indicate that in adult rats, target-derived NGF, BDNF, and NT3 do not regulate the survival of septal cholinergic neurons in proportion to the number of target neurons present. Moreover, the findings suggest that one or more of these target-derived neurotrophins regulate the structural and chemical phenotype of these neurons in the adult.

Recent identification of the gene for Huntington's disease is currently attracting widespread attention. While having importance for predictive testing and the potential of elucidating the underlying disease process, this discovery does not yet provide any advances for therapeutic intervention. Here we review recent advances in the development of improved animal models of Huntington's disease and strategies for its repair. Novel toxins may better mimic the neuropathology, and provide important clues about the underlying metabolic disorder, of the human disease. In addition, recent experiments into the cellular morphology, development and function of striatal cell transplants in both rats and monkeys are now indicating the prospect of viable strategies for structural repair in this disorder.

The role of trophic factors in the adult central nervous system (CNS) is poorly understood. One system that may require trophic factors, particularly nerve growth factor (NGF) and brain-derived growth factor (BDNF), for normal function in the adult CNS is the cholinergic projection from the basal forebrain to the hippocampus. To study the nature of this requirement we ablated target neurons in the hippocampus that normally produce NGF and BDNF; we found no loss of cholinergic neurons or cholinergic phenotype in the medial septum in young adult rats. In similarly treated aged rats (24-33 months), some reduction in cholinergic phenotype was found, in the absence of cell death for up to 90 days. Thus, these cholinergic neurons either do not require trophic support for survival, or are able to obtain trophic factors from other sources for the duration of the experiments. In vitro, NGF withdrawal from septal neurons initially grown in the presence of NGF did not result in the death of old cholinergic neurons in these tissue cultures but did result in a down-regulation of transmitter-associated enzymes, accompanied by cholinergic cell shrinkage and a reduction in fiber density. Together, these findings suggest that target-derived factors may not be required for the survival of mature septal cholinergic neurons, but may be involved in maintenance of cholinergic and structural phenotype.

Many neurons in the medial septal nucleus lose their transmitter-associated enzyme staining following axotomy in the proximal fimbria-fornix (FF), but it is not clear if these neurons have died or persist in a shrunken and subfunctional state. To investigate this further, septal neurons projecting through the FF were labelled with the fluorescent dye, True blue, by retrograde transport from multiple bilateral injection sites in the hippocampus. True blue-labelled neurons and cholinergic neurons immunohistochemically stained for choline acetyltransferase (ChAT) were then quantitatively compared in neighbouring sections through the medial septum 28 days after complete unilateral transections of the proximal FF. The number of True blue and ChAT positive cells ipsilateral to the FF lesion showed significant (P less than 0.001) declines of 51.4% and 71.1%, respectively, relative to the unlesioned side. Cell loss was considerably more severe among large neurons, such that 78.0% and 92.7% of True blue and ChAT labelled cells larger than the normal mean, but only 40.1% and 68.0% of True blue and ChAT labelled cells smaller than the normal mean size were lost. This indicates either that larger neurons were more prone to cell loss, or that some (but not all) large neurons persisted in a shrunken form. Histograms showed no increase in cell number in any of the smaller size categories and a substantial decrease in most cases, indicating that shrinkage alone could not account for the loss of all large neurons. Since True blue can remain present in brainstem cholinergic neurons surviving for over 365 days after axotomy, loss of True blue suggests breakdown of membrane integrity and cell death.(ABSTRACT TRUNCATED AT 250 WORDS)

Target cells are thought to regulate the survival of afferent neurons during development by supplying limiting amounts of neurotrophic factors, but the degree to which afferent neurons remain dependent on target-derived support in the adult is uncertain. In this study, uninjured basal forebrain cholinergic neurons did not die after excitotoxic ablation of their target neurons in young adult rats, indicating that they are either not dependent on neurotrophic factors for survival or can obtain trophic support from other sources after target neurons are lost. This finding suggests that cholinergic cell death in neurodegenerative conditions such as Alzheimer's disease is not due solely to a loss of target neurons or factors provided by them.

Shock is defined as a secondary condition constituting a complication to a primary disease of which more than 100 are recorded in the literature. Shock is characterized by prolonged circulatory inadequacy leading to insufficient tissue perfusion and cell death. According to etiology shock is classified into three main groups: hypovolemic, vasogenic and cardiogenic shock. Taking hypovolemic shock as a model the pathgenesis of shock is presented. Hypovolemia acts on the baroreceptors giving rise to a sympatho-adrenal response resulting in increased vasoconstriction, which again leads to viscerocutaneous ischemia. This phase is known as the ischemic anoxic or centralized shock phase. Without treatment this phase develops into the second socalled stagnant anoxic or paralytic shock phase. "Irreversible shock" is discussed. The pathogenesis of vasogenic and cardiogenic shock is mentioned and compared with hypovolemic shock. It is emphasized that the sympatho-adrenal response is the central and common feature in every shock development. Special reference is made to septic shock with its outstanding circulatory conditions (arteriovenous shunting). Lacticacidemia and metabolic acidosis are described as the most important metabolic alterations in shock. With reference to pathenesis the main clinical symptoms of shock are presented: increased heart rate, initially pale later hyperemic, congested and terminally cyanotic mucosae, increased capillary filling time, cold skin and low body temperature. All these signs are related to the sympatho-adrenal response. It is pointed out that the patient in shock is depressed. Inevitably the primary disease will modify the shock symptoms. Hyperemia with edema, hemorrhages and thrombosis in organs and tissues are morphological manifestations of shock. Later microscopically detectable degenerative and necrotic alterations develop, and there are signs of intravascular coagulation (hyaline thrombi and spheres). Due to the rather nonspecific macroscopic alterations a post mortem shock diagnosis necessitates for completion histology and/or a clinical shock diagnosis. Some of the most important shock-provoking primary diseases dealt with in veterinary practice are mentioned along with their possible shock pathogenesis. Referring to the shock pathogenesis the therapy is discussed. The first and indispensable therapeutical measure in treating shock per se is increasing the circulating blood volume, Balanced electrolyte solutions are preferred. Examples of composition, doses (up to 80--200 ml/kg body weight) and infusion rate (initially 15--30 ml/kg body weight during the first 10--20 min., then quantum satis) are given.

42 horses were examined. The physical signs with relation to circulatory insufficiency and the abdominal disease were registered following a two-phased examination procedure. Great prognostic value was found in the degree of circulatory insufficiency judged by pulse rate and character, filling of the jugular vein, skin temperature, colour of mucous membranes, capillary refill time, sweating, depression, skin turgor and degree of enophthalmus. In making a causal diagnosis the abdomen was examined for shape, tenderness, peristaltic sounds, gastric dilation by siphoning, abnormal rectal findings and macroscopic changes in peritoneal fluid. Greatest diagnostic difficulties were encountered in cases of intestinal atonia, acute enteritis and torsion of the colon. In selected (severe) cases laboratory tests were obtained. Blood samples were examined for packed cell volume, hemoglobin, red and white blood cell counts, differential white blood cell count, blood gases and acid-base status, lactate, serum total protein and albumin, plasma sodium, potassium, chloride, calcium, magnesium, inorganic phosphorus, glucose, creatinine, BUN, total bilirubin, ASAT, CK, BASP and GGT. Peritoneal fluid was examined for red blood and white cell counts, total protein, specific gravity, pH and lactate, and enzymes as in blood. Laboratory results generally confirmed the clinical signs of shock, and packed cell volume and blood lactate were regarded to be of greatest prognostic interest. Although the performed laboratory information, macroscopic evaluation was thought to reveal sufficient information in most cases. It was concluded that supervening shock is of decisive importance in severe forms of colic, and that a careful and repeated evaluation of the circulatory insufficiency often provides one with a tentative prognosis although the final diagnosis is not obtained. In spite of therapy fatal outcome was found in all seriously shocked horses.

Thioridazine (THD) and its major metabolites, mesoridazine (MES), sulforidazine (SULF), and northioridazine (norTHD) accumulate at a predictable rate in human brain tissue after chronic medication. Although the concentration of THD is normally lower than or the same as its major metabolite, MES, in the plasma, it was found to be up to five times as concentrated in the brain tissue of treated patients. THD and its metabolites were evenly distributed throughout all regions of the brain in chronically medicated patients. Brain concentrations of THD were also compared with those of chlorpromazine (CPZ) when both drugs had been given at the same dose before death, and were shown to be up to 10 times more concentrated in brain at doses greater than 300 mg/day. Because some of the metabolites of THD are pharmacologically active, it is important to know how they accumulate in the brain in relation to the parent compound to understand how this drug mediates its clinical effect.

Although several studies have documented reduced concentrations of somatostatin-like immunoreactivity (SLI) in the cerebral cortex in Alzheimer's disease, there is controversy concerning the extent and importance of these changes. We measured SLI in brains obtained post mortem from 12 patients with pathologically confirmed Alzheimer's disease and from 13 neurologically normal controls. All major cortical and subcortical regions were examined. Widespread reductions of SLI in Alzheimer's disease cerebral cortex were found, with the most profound changes seen in temporal lobe; but there also were major reductions in both the frontal and occipital cortex. There were no significant reductions in subcortical regions. Characterization of SLI by high-pressure liquid chromatography showed no significant difference in profiles between Alzheimer's disease and control frontal cortex. These results suggest that the reduction in somatostatin immunoreactivity in Alzheimer's disease may be caused by degeneration of intrinsic somatostatin cortical neurons.

Although a biochemical abnormality has been postulated in the etiology of schizophrenia, evidence supporting this hypothesis has been conflicting. Because of the presence of somatostatin-like immunoreactivity (SLI) in limbic system nuclei of the brain, we examined postmortem concentrations of SLI in patients dying with schizophrenia and in normal controls. Concentrations of SLI in Brodmann cortical area 38, hippocampus, caudate, putamen, nucleus accumbens, and both segments of the globus pallidus were not significantly different from controls. In addition, we examined both SLI and neuropeptide-Y-like immunoreactivity (NPYLI) in subnuclei of the amygdala and the substantia innominata. There were no significant alterations in either neuropeptide as compared with controls.

A non-mammalian lamprey-like gonadotropin-releasing hormone (lGnRH) has been detected in human hypothalami using a combination of immunocytochemistry, high performance liquid chromatography and radioimmunoassay. The hypothalamic distribution of immunopositive lGnRH neurons is similar to that observed for those containing the mammalian gonadotropin-releasing hormone (mGnRH), indicating a possible role for this newly identified peptide in the regulation of pituitary function. Our data suggest the existence of a separate gene for lamprey-like GnRH in humans. Confirmation of the exact nature and role of this newly detected form of GnRH will require future isolation and sequence analysis. The possibility that polygenic expression of a given peptide may be a common phenomenon even in higher mammals is discussed.

Some hemodynamic and hematologic effects of acute experimental lactic acidemia in 3 healthy cows are presented. Lactic acidemia was induced by intravenous infusion of a 10% solution of racemic lactic acid. The prominent features of the acidification of the blood were increases in carotid artery blood pressure and responses to intravenously injected norepinephrine, slight bradycardia and slight hyperventilation. Intravascular hemolysis with hemoglobinuria was a constant finding. Otherwise, no adverse effects of the acidemia were noted. These changes were paralleled by a progressive fall in arterial blood pH, base excess and PCO2 and increasing venous blood L (+)-lactate concentrations A reasonable explanation for the hemodynamic effects of the acidemia is peripheral vasoconstriction elicited by either stimulation of the sympathetic nervous system or increased sensitivity of vasoconstrictive receptors. The results are discussed with special reference to primary lactic acidosis encountered in grain engorgement in ruminants and to the secondary lactic acidosis of shock. These conditions are characterized by hemoconcentration and hypovolemia. Therefore, the results of this study of healthy normovolemic cows may not be valid in the severely dehydrated, hemoconcentrated and acidemic cow as hypotension is reported in the literature in connection with ruminal acidosis in sheep.

Two cases of male pseudohermaphroditism in the dog are described, including clinical, macroscopic, microscopic, karyotypic and therapeutic features. The external appearance of both dogs was that of an otherwise normal bilateral cryptorchid. Both dogs developed signs of male feminizing syndrome at 7 and 5 years of age respectively. This prompted exploratory laparotomy, disclosing an uterus, testes at the ovarian sites and Sertoli cell tumours. It is emphasized to include malformations of the genital apparatus in the differential diagnosis of canine urological and endocrine disease.

Thirteen phenothiazine compounds were separated chromatographically using high performance liquid chromatography with coulometric electrochemical detection. These could be extracted from brain tissue using direct homogenization in tetrahydrofuran followed by one centrifugation, evaporation of supernatant and reconstitution in water. Fluphenazine was used as the internal standard. The absolute lower limit of detection was approximately 50 pg/mg wet tissue, and recovery rates for most standards added to brain homogenates were greater than 85%. Chromatograms from patients receiving chlorpromazine (600 mg) and thioridazine (600 mg) are shown and endogenous brain levels quantified. The results are discussed with respect to their relevance in schizophrenic research.

This paper describes in detail the acetylcholinesterase (AChE) staining characteristics of the normal human amygdaloid complex using fixed post-mortem brain tissue. It was shown that the differential AChE staining of the amygdala could be used to accurately delineate amygdaloid subdivisions macroscopically. Using the same staining method on the amygdala from brains previously frozen and stored at -70 degrees C resulted in a staining pattern similar to that seen using fixed tissue, despite numerous ice artifacts. It was concluded that this stain may be useful to researchers working on post-mortem human amygdala, particularly those involved in microdissecting this region for neurochemical analysis.

Neuropeptide Y is a 36-amino acid peptide that is found in high concentrations in cerebral cortex and is contained in cortical neurons. We measured concentrations of this peptide in postmortem tissue from patients with Alzheimer's disease and controls using a sensitive and specific radioimmunoassay. High-performance liquid chromatography showed that more than 95% of immunoreactivity co-migrated with synthetic standards in both Alzheimer's disease and control frontal cortex. Significant reductions in neuropeptide Y-like immunoreactivity were found in eleven cortical regions, the hippocampus, and the locus ceruleus. The regions particularly affected included the temporal lobe, frontal lobe, and occipital cortex. As neuropeptide Y is co-localized with somatostatin in a considerable proportion of cortical neurons, the loss of immunoreactivity may in part reflect degeneration of these neurons. Further study of the selective vulnerability of these neurons in Alzheimer's disease cortex may provide clues to the nature of the underlying disease process.

Two principal features of Alzheimer's disease (AD) are (1) the occurrence of neurofibrillary tangles (NFTs) and senile plaques, and (2) the loss of cortical cholinergic activity because of dysfunction of neurons in the basal forebrain cholinergic system. The relationship of these two abnormalities is an unresolved issue in the pathology of AD. We used polyclonal antibodies specific for paired helical filaments (PHFs), combined with acetylcholinesterase (AChE) histochemistry, to assess the cytoskeletal changes of cholinergic and noncholinergic neurons in the basal forebrain in AD. In both sporadic and familial AD, the nucleus basalis of Meynert (nbM) showed a marked decrease in AChE-positive (AChE+) perikarya and abundant immunoreactive NFTs. In double-labeling studies of the nbM, PHF reactivity was found both in surviving AChE+ neurons and in many AChE- NFTs that were not associated with microscopically recognizable cell structures. Some surviving AChE+ perikarya did not contain NFTs. Numerous NFTs and senile plaques were identified by PHF immunoreactivity in other basal forebrain areas, including subnuclei of the amygdala that showed low or absent AChE activity. We conclude that the dysfunction and death of cholinergic neurons in the nbM is associated with extensive NFT formation, including apparently residual NFTs in loci where nbM neurons once existed; and many noncholinergic neurons and neurites in the basal forebrain show NFT and senile plaque formation. The cytopathology of AD involves neurons of varying transmitter specificities, including cholinergic neurons in the basal forebrain.

The binding characteristics of the enantiomers of thioridazine were assessed in the brain of the rat using competitive radioreceptor assays with tritiated ligands selective for dopamine D1 (SCH-23390), D2 (spiperone), norepinephrine alpha-1 (prazosin) and muscarinic (quinuclinidinyl benzilate) receptors. (+)-Thioridazine was shown to have 2.7 and 4.5 times higher affinity than (-)-thioridazine for D2 and alpha-1 receptors, respectively. In contrast, (-)-thioridazine had 10 times higher affinity for the D1 receptor. Both enantiomers showed similar affinities for the muscarinic receptor. In a second experiment, thioridazine, dopamine, norepinephrine, serotonin and their metabolites were assayed in the brain of the rat after acute administration of the enantiomers of thioridazine and the assessment of catalepsy. (+)-Thioridazine was 4.1 times as potent as (-)-thioridazine in elevating the turnover of dopamine in the striatum, but neither enantiomer affected the other monoamines. The concentration of thioridazine and its metabolites in the brain, for a given dose, was similar for both enantiomers. (-)-Thioridazine induced slightly more catalepsy than (+)-thioridazine and appeared to be more toxic at large doses. While racemic thioridazine had an intermediate effect between that of its two enantiomers in the binding and neurochemical assays, it appeared to induce more catalepsy than either enantiomer, suggesting a synergistic effect in this behavioral assay. It was concluded that (+)- and (-)-thioridazine act as partially selective D2 and D1 antagonists, respectively. Therefore, clinical administration of only one enantiomer of thioridazine, rather than the currently prescribed racemate, may result in an improved therapeutic profile and so be worthy of further investigation.

One-day-old chickens were fed ochratoxin A-contaminated diets at 2 levels: 0.3 and 1 mg ochratoxin A per kg feed, for 341 days. The only observable lesion to develop was a kidney damage comparable with the naturally occurring avian nephropathy. The changes in renal function were characterized by impairment of glomerular and tubular function, indicated by a decreased inulin clearance, TmPAH and decreased urine concentrating capacity. The changes of renal structure included degeneration of the tubular epithelium accompanied by regeneration. At slaughter, the kidneys, liver and muscular tissue of the birds contained residues of ochratoxin A (up to 50 mug per kg). As all the birds would have passed the meat inspection because no macroscopical lesions were present, this represents a possible health problem.

Experimental closed loop small intestinal volvulus was studied in the anesthetized horse. Volvulus was simulated by ligation of the mesenterial veins to a segment of small intestine. Physical signs and hemodynamic, hematologic, clinical chemical, bacteriologic and peritoneal fluid values were examined. Compared to conscious horses anesthesia highly delayed and modified the clinical signs of shock (changes in mucosal colour, dehydration, decreased skin temperature, elevated pulse rate, low blood pressures) and of small intestinal volvulus (altered peristalsis, gastric dilation). Plasma glucose response to shock was also modified by unconsciousness. However, a dose response relationship was indicated between the extent of small intestinal damage and clinical symptoms. The same was applicable to changes in blood pressures, blood acid-base balance, lactate, potassium, chloride, glucose, inorganic phosphorus, creatinine, creatine kinase, red blood cell and total white blood cell counts and serum total protein. The relationship was also indicated in the following peritoneal fluid values: volume, lactate, pH, total white cell counts, alkaline phosphatase and bacteriology. Changes related to shock (insufficient tissue perfusion) were low blood pressures and metabolic acidosis due to anaerobic glycolysis with accumulation of lactic acid. Also low plasma glucose and elevated plasma potassium, creatinine, inorganic phosphorus and creatine kinase were regarded as consequences of shock.