What doesn't kill you might make you stronger: functional basis for variation in body armour.

1. Predation has been proposed to be a selective agent in the evolution of morphological antipredator strategies in prey. Among vertebrates, one of the morphological traits that evolved multiple times is body armour, including carapaces, thickened keratinized scales and plates of dermal bone. 2. It has been generally assumed that body armour provides protection against a predatory attack; yet, few explicit tests of the hypothesis exist. Cordylidae, a relatively small family of southern African lizards, show considerable variation in the degree of body armour. Hence, this family provides an opportunity to test the hypothesis that body armour serves as protection against predators. 3. Experiments were conducted to test whether the bite forces of four species of mammalian predators were high enough to penetrate the skins of Karusasaurus polyzonus, Namazonurus peersi, Cordylus cordylus and Cordylus macropholis, as well as those of Ouroborus cataphractus individuals originating from three localities that differed in their predator diversity. Furthermore, histological techniques were used to test whether variation in skin toughness was associated with concomitant changes in the degree of epidermal (i.e. ß-keratin) and dermal (i.e. osteoderm) armour. 4. The skin toughness values for four out of five cordylid lizards tested in this study were well below the bite forces of the mammalian predators. In contrast, the thick osteoderms in the dermis of O. cataphractus can withstand bites from several mongoose species. However, the significant variation in body armour that is present between the three populations of O. cataphractus does not seem to be related to predator diversity. 5. It is concluded that body armour can serve as protection against predation in O. cataphractus, but that alternative selection pressures, such as thermoregulation or predation by snakes, presumably underlie variation in defensive morphology in the other cordylid lizards.

Automatic section thickness determination using an absolute gradient focus function.

Quantitative analysis of microstructures using computerized stereology systems is an essential tool in many disciplines of bioscience research. Section thickness determination in current nonautomated approaches requires manual location of upper and lower surfaces of tissue sections. In contrast to conventional autofocus functions that locate the optimally focused optical plane using the global maximum on a focus curve, this study identified by two sharp 'knees' on the focus curve as the transition from unfocused to focused optical planes. Analysis of 14 grey-scale focus functions showed, the thresholded absolute gradient function, was best for finding detectable bends that closely correspond to the bounding optical planes at the upper and lower tissue surfaces. Modifications to this function generated four novel functions that outperformed the original. The 'modified absolute gradient count' function outperformed all others with an average error of 0.56 µm on a test set of images similar to the training set; and, an average error of 0.39 µm on a test set comprised of images captured from a different case, that is, different staining methods on a different brain region from a different subject rat. We describe a novel algorithm that allows for automatic section thickness determination based on just out-of-focus planes, a prerequisite for fully automatic computerized stereology.

Between a rock and a hard polytomy: rapid radiation in the rupicolous girdled lizards (Squamata: Cordylidae).

Girdled lizards (Cordylidae) are sub-Saharan Africa's only endemic squamate family and contain 80 nominal taxa, traditionally divided into four genera: Cordylus, Pseudocordylus, Chamaesaura and Platysaurus. Previous phylogenetic analysis revealed Chamaesaura and Pseudocordylus to be nested within Cordylus, and the former genera were sunk into the later. This taxonomic revision has received limited support due to the study's poor taxon sampling, weakly supported results and possible temporary nomenclatural instability. Our study analyzes three nuclear and three mitochondrial genes from 111 specimens, representing 51 in-group taxa. Parsimony, likelihood and Bayesian analyses of concatenated and partitioned datasets consistently recovered a comb-like tree with 10, well-supported, monophyletic lineages. Our taxonomic reassessment divides the family into 10 genera, corresponding to these well-supported lineages. Short internodes and low support between the non-platysaur lineages are consistent with a rapid radiation event at the base of the viviparous cordylids.

A new Nucras Gray, 1838 (Squamata: Lacertidae) from the Strandveld of the Western Cape, South Africa.

A striking new sandveld lizard of the Nucras tessellata group is described from the Lambert's Bay Strandveld of the Western Cape Province, South Africa. It is sister to the clade N. livida + N. tessellata, and is phenetically most similar to N. tessellata, from which it differs in its more elongate body and possibly increased number of presacral vertebrae and patternless orange dorsal coloration. The form elegans, described as a species by Andrew Smith (1838), but treated as an infrasubspecific variant by Broadley (1972), also exhibits weak patterning, but is likely a regional color variant. Nucras aurantiaca sp. nov. is the ninth member of the genus found in southern Africa. Its discovery in the well-collected coastal Western Cape suggests that further herpetofaunal surveys are needed in this region, which is threatened by agricultural activity and tourism-related development.

[A 'psychogenic psychosis' turns out to be a subarachnoid haemorrhage. A case study]. / Een 'psychogene psychose' blijkt een subarachnoïdale bloeding te zijn.

A 50-year-old woman is admitted to the emergency ward by reason of her psychotic state. Because she has a history of psychiatric problems and has been previously diagnosed as having borderline personality disorder it is assumed that she has had a brief psychogenic psychosis. When the psychosis recurs and the symptoms increase in intensity the patient is given a computerized tomography brain scan. The scan reveals a subarachnoid haemorrhage. In discussing this case history we try to interpret the symptoms of this neurological disorder against the background of the premorbid psychiatric diagnosis. We supplement our interpretation with data from case histories reported in the literature.

Enemy at the gates: Rapid defensive trait diversification in an adaptive radiation of lizards.

Adaptive radiation (AR), the product of rapid diversification of an ancestral species into novel adaptive zones, has become pivotal in our understanding of biodiversity. Although it has widely been accepted that predators may drive the process of AR by creating ecological opportunity (e.g., enemy-free space), the role of predators as selective agents in defensive trait diversification remains controversial. Using phylogenetic comparative methods, we provide evidence for an "early burst" in the diversification of antipredator phenotypes in Cordylinae, a relatively small AR of morphologically diverse southern African lizards. The evolution of body armor appears to have been initially rapid, but slowed down over time, consistent with the ecological niche-filling model. We suggest that the observed "early burst" pattern could be attributed to shifts in vulnerability to different types of predators (i.e., aerial versus terrestrial) associated with thermal habitat partitioning. These results provide empirical evidence supporting the hypothesis that predators or the interaction therewith might be key components of ecological opportunity, although the way in which predators influence morphological diversification requires further study.

Loss of the presynaptic vesicle protein synaptophysin in hippocampus correlates with cognitive decline in Alzheimer disease.

We tested the hypothesis that synaptic defects in the hippocampus of individuals with Alzheimer disease (AD) correlate with the severity of cognitive impairment. Three postmortem groups were studied: controls with normal and stable cognition; cognitively intact subjects with senile plaque densities diagnostic for possible AD (p-AD) and neurofibrillary changes characteristic of early AD (Braak stage III); and individuals with definite AD and neurofibrillary changes typical of incipient to severe AD (Braak stage III, V, or VI). Synaptophysin (a presynaptic vesicle protein) levels were quantified by immunoblotting of synaptic membrane fractions isolated from hippocampus, entorhinal cortex, caudate nucleus, and occipital cortex. Average synaptophysin levels were reduced in hippocampus when comparing definite AD to controls (55%, p < 0.0001), p-AD to control (25%, p < 0.005), and definite AD to p-AD (30%, p < 0.05), but levels in entorhinal cortex, occipital cortex, and caudate nucleus were either unchanged or less significantly altered than in hippocampus. By univariate analysis, hippocampal synaptophysin levels correlated with neuropsychological measurements, including Mini-mental state examination scores (r = 0.83, p < 0.0001) and Blessed scores (r = 0.74, P < 0.001), and with senile plaque densities (r = 0.89, p < 0.0001). We conclude that synaptic abnormalities in the hippocampus correlate with the severity of neuropathology and memory deficit in individuals with AD, and that this defect may predate neuropsychological evidence for cognitive impairment early in AD.

Stereological analysis of cerebral atrophy in human immunodeficiency virus-associated dementia.

Brain atrophy is a common finding in patients with AIDS, but the relationship of atrophy to HIV-associated dementia is unclear. We used unbiased, stereological methods on postmortem brain specimens to estimate volumes of different brain regions in patients prospectively diagnosed with and without HIV-associated dementia. Thirty HIV-seropositive (9 without AIDS/without dementia, 6 with AIDS/without dementia, 15 with AIDS/with dementia) and 7 HIV-seronegative controls were studied using the technique of point counting and Cavalieri's principle of volume estimation. There was a significant reduction in the mean neocortical volume (15%, p = 0.032) in the group with AIDS when compared to the seronegative controls, and this difference was accentuated when comparing only the group with HIV-associated dementia to the seronegatives (neocortex: 18%, p = 0.020). There were no significant differences between the AIDS groups with and without HIV-associated dementia, although there was a trend for smaller volumes in the most severely demented patients. There were no differences in white matter volumes between groups. In conclusion, patients dying with AIDS and particularly those with HIV-associated dementia, show significant neocortical atrophy when compared to seronegative controls. The lack of a significant difference in cerebral atrophy between HIV-seropositive patients with and without dementia suggests that atrophy may be a more generalized phenomenon of AIDS as opposed to a specific marker for HIV-associated dementia.

Cognitive decline strongly correlates with cortical atrophy in Alzheimer's dementia.

Alzheimer's disease (AD) is characterized by progressive dementia and distinct neuropathology at autopsy. In order to test the relationship between dementia severity and loss of brain volumes, we prospectively documented the neurological/medical health of 26 male and 26 female controls and AD cases, and evaluated a subset of controls and AD cases using the Mini Mental State Examination (MMSE). At autopsy, Consortium to Establish a Registry for Alzheimer's Disease (CERAD) criteria confirmed diagnoses in 33 AD cases and 19 controls, and using unbiased stereology we quantified total volumes of cortical gray matter, subcortical grey matter including white matter, and forebrain. For ages of death between 50 to 100 years, controls showed minor cortical atrophy in the absence of cognitive decline. Cortical atrophy in AD cases was 20 to 25% greater than that in controls; AD patients dying at older ages showed less severe cortical atrophy than those dying at younger ages. Across all AD cases there was a strong correlation between cognitive performance on the Mini Mental State Examination and cortical volume loss. These findings confirm fundamental differences in the temporal patterns of cortical volume loss in aging and AD, and support cortical degeneration as the primary basis for cognitive decline in AD.

Hippocampal neuron and synaptophysin-positive bouton number in aging C57BL/6 mice.

A loss of hippocampal neurons and synapses had been considered a hallmark of normal aging and, furthermore, to be a substrate of age-related learning and memory deficits. Recent stereological studies in humans have shown that only a relatively minor neuron loss occurs with aging and that this loss is restricted to specific brain regions, including hippocampal subregions. Here, we investigate these age-related changes in C57BL/6J mice, one of the most commonly used laboratory mouse strains. Twenty-five mice (groups at 2, 14, and 28-31 months of age) were assessed for Morris water-maze performance, and modern stereological techniques were used to estimate total neuron and synaptophysin-positive bouton number in hippocampal subregions at the light microscopic level. Results revealed that performance in the water maze was largely maintained with aging. No age-related decline was observed in number of dentate gyrus granule cells or CA1 pyramidal cells. In addition, no age-related change in number of synaptophysin-positive boutons was observed in the molecular layer of the dentate gyrus or CA1 region of hippocampus. We observed a significant correlation between dentate gyrus synaptophysin-positive bouton number and water-maze performance. These results demonstrate that C57BL/6J mice do not exhibit major age-related deficits in spatial learning or hippocampal structure, providing a baseline for further study of mouse brain aging.

Stereological analysis of astrocyte and microglia in aging mouse hippocampus.

Recent evidence suggests neuroglia-mediated inflammatory mechanisms may stimulate neurodegenerative processes in mammalian brain during aging. To test the hypothesis that the number of microglia and astrocytes increase in the hippocampus during normal aging, unbiased stereological techniques were used to estimate total cell number in hippocampal subregions (CA1, dentate gyrus and hilus) of male C57BL/6J mice of different ages: 4-5 months, 13-14 months and 27-28 months. Immunocytochemical visualization for microglia and astrocytes were via Mac-1 and GFAP antibody, respectively. Estimates of total microglia and astrocyte number were assessed using the optical fractionator. No statistically significant age differences were found in the numbers of microglia or astrocytes in the hippocampal regions sampled. These findings suggest that age-related increases in the total numbers of hippocampal microglia and astrocytes is not causal for observed age-related increases in cytokine response.

Estrogens modulate experimentally induced apoptosis of granule cells in the adult hippocampus.

Estrogens are known to have broad effects on neuronal plasticity, but their specific role in neuronal cell death has not been determined. In the present study, we investigated the effects of beta-estradiol on an experimental model of apoptosis of granule cells of the dentate gyrus, i.e., apoptosis induced by intraventricular injection of the microtubule polymerization inhibitor colchicine. Cell death was characterized with multiple methods, including TUNEL and DNA electrophoresis. Nonrandom digestion of DNA was observed within 8-10 hours after colchicine injection, followed by condensation and fragmentation of granule cell nuclei and extensive anterograde degeneration of mossy fibers/terminals in 2 days. We compared the outcomes of the above-described manipulation in ovariectomized or sham-operated rats and animals treated daily with beta-estradiol or vehicle. Animals were lesioned with colchicine or vehicle 2 weeks after ovariectomy or sham operation. Beta-estradiol or vehicle was administered for 1 week prior to lesion and was continued for a further 2 weeks. Total numbers and densities of granule cells in different animal groups were counted by stereology in various anteroposterior levels of the hippocampus. Our results show that ovariectomy intensifies colchicine-induced granule cell apoptosis, which is ameliorated by exogenous beta-estradiol. In doses that ameliorate the adverse effect of ovariectomy, exogenous beta-estradiol appears to have no effect of preventing granule cell death in animals with intact ovaries; i.e., an estrogen excess is not more neuroprotective than physiological levels of these hormones. Taken together, our results indicate that estrogen deprivation increases the vulnerability of hippocampal neurons to injury and may predispose to neurological diseases occurring after menopause.

Spectrum of clinical and electrophysiologic features in HNPP patients with the 17p11.2 deletion.

OBJECTIVE: To study the clinical and electrophysiologic features of a large series of carriers of the 17p11.2 deletion. BACKGROUND: The 17p11.2 deletion is associated in most patients with recurrent acute nerve palsies, which is the typical presentation of hereditary neuropathy with liability to pressure palsies (HNPP). Nevertheless, a few other phenotypes have been reported. METHODS: On the basis of clinical and electrophysiologic data, the authors conducted a retrospective study of 99 individuals with the 17p11.2 deletion referred to their neurogenetic department between 1993 and 1997. RESULTS: In addition to the typical presentation of HNPP, they describe five other phenotypes in 15 patients: recurrent positional short-term sensory symptoms, progressive mononeuropathy, Charcot-Marie-Tooth disease-like polyneuropathy, chronic sensory polyneuropathy, and chronic inflammatory demyelinating polyneuropathy-like, recurrent subacute polyneuropathy; and 14 asymptomatic patients. In all the deletion carriers, regardless of their phenotype and by the second decade, the authors found a characteristic, multifocal electrophysiologic neuropathy consisting of a diffuse increase in distal motor latencies contrasting with normal or moderately reduced motor nerve conduction velocities, a diffuse reduction in sensory nerve action potential, and multiple focal slowing of nerve conduction at the usual sites of entrapment. The key diagnostic criterion is a bilateral slowing of sensory and motor nerve conduction at the carpal tunnel with at least one abnormal parameter for motor conduction in one peroneal nerve. CONCLUSION: The authors confirm the clinical phenotypic heterogeneity of the 17p11.2 deletion and suggest that electrophysiologic examination is a reliable tool for screening suspected HNPP patients in its various clinical presentations.

Macrophagic myofasciitis associated with inclusion body myositis: a report of three cases.

We describe three patients with macrophagic myofasciitis and inclusion body myositis. All patients fulfilled diagnostic criteria for inclusion body myositis and myopathologic criteria for macrophagic myofasciitis. In the three cases macrophagic myofasciitis complicated the evolution of a known and painless inclusion body myositis and was diagnosed in a repeated deltoid biopsy because of the appearance of myalgia during the course of inclusion body myositis in all cases. The unexpected appearance of myalgia during the course of painless inclusion body myositis must arouse the suspicion of an association of another inflammatory muscle disease, macrophagic myofasciitis.

Effects of estrogen and raloxifene on neuroglia number and morphology in the hippocampus of aged female mice.

Hormone replacement therapy with the gonadal steroid estrogen or synthetic agents such as raloxifene, a selective estrogen receptor modulator, may affect cellular function in brains of postmenopausal women. In vitro studies suggest that 17beta estradiol and raloxifene can alter the microglial and astrocyte expression of immuno-neuronal modulators, such as cytokines, complement factors, chemokines, and other molecules involved in neuroinflammation and neurodegeneration. To directly test whether exogenous 17beta estradiol and raloxifene affect the number of glial cells in brain, C57BL/6NIA female mice aged 20-24 months received bilateral ovariectomy followed by s.c. placement of a 60-day release pellet containing 17beta estradiol (1.7 mg), raloxifene (10 mg), or placebo (cholesterol). After 60 days, numbers of microglia and astrocytes were quantified in dentate gyrus and CA1 regions of the hippocampal formation using immunocytochemistry and design-based stereology. The results show that long-term 17beta estradiol treatment in aged female mice significantly lowered the numbers of astrocytes and microglial cells in dentate gyrus and CA1 regions compared with placebo. After long-term treatment with raloxifene, a similar reduction was observed in numbers of astrocytes and microglial cells in the hippocampal formation. These findings indicate that estrogen and selective estrogen receptor modulators can influence glial-mediated inflammatory pathways and possibly protect against age- and disease-related neuropathology.

Length measurement: new developments in neurostereology and 3D imagery.

Quantification of linear biological structures has important applications in neuroscience; for example, the length of neurotransmitter-specific axonal innervation or length of dendritic processes within particular brain structures. Until recently, however, there have been practical limitations in the application of stereological tools for the unbiased estimation of object length on tissue sections. The recent development of efficient new approaches allows for the wider application of theoretically unbiased sampling and estimation techniques that are devoid of the assumptions and models of earlier methods. In this review, we outline the historical background and recent advances in the estimation of total length for biological objects on tissue sections, including a practical method to estimate the length of cholinergic fibers using newly developed methods. These newer methods also take advantage of three-dimensional image datasets and virtual probes, techniques that may have wider application in quantitative morphometry.

Length measurement: new developments in neurostereology and 3D imagery.

Quantification of linear biological structures has important applications in neuroscience; for example, the length of neurotransmitter-specific axonal innervation or length of dendritic processes within particular brain structures. Until recently, however, there have been practical limitations in the application of stereological tools for the unbiased estimation of object length on tissue sections. The recent development of efficient new approaches allows for the wider application of theoretically unbiased sampling and estimation techniques that are devoid of the assumptions and models of earlier methods. In this review, we outline the historical background and recent advances in the estimation of total length for biological objects on tissue sections, including a practical method to estimate the length of cholinergic fibers using newly developed methods. These newer methods also take advantage of three-dimensional image datasets and virtual probes, techniques that may have wider application in quantitative morphometry.

Absolute number and size of pigmented locus coeruleus neurons in young and aged individuals.

Significant loss of noradrenergic neurons of the locus coeruleus in aging and Alzheimer's disease has been reported. The interpretation of these analyses, however, is problematic because of the model- and assumption-based nature of conventional sampling and estimation techniques. In the present study, unbiased stereological methods were used to estimate the total number and mean cell volume of pigmented neurons of the locus coeruleus in the brains of young and aged nondemented persons. No side-to-side differences are seen, and there is no change in pigmented cell number or size in the locus coeruleus of nondemented older persons as compared with that of young individuals. In light of previous studies that show severe locus coeruleus cell loss in Alzheimer's disease, these data support further critical investigations into the possible protective role of noradrenaline in normal cognitive functions and emphasize the importance of avoiding methodological bias in quantitative neuroanatomical studies.

Notch3 mutations in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a mendelian condition causing stroke and vascular dementia.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited condition whose key features include recurrent subcortical ischemic events, migraine attacks and vascular dementia in association with diffuse white-matter abnormalities seen on neuroimaging. Pathologic examination shows multiple small deep cerebral infarcts, a leukoencephalopathy and a nonatherosclerotic nonamyloid angiopathy involving mainly the media of small cerebral arteries. To progress in understanding the pathophysiological mechanisms of this condition, we undertook the identification of the mutated gene. We mapped the CADASIL gene on chromosome 19p13.1. More than 120 families have been referred to our lab. Genetic linkage analysis of 33 of these families allowed us to reduce the size of the genetic interval to less than 1 cM and to demonstrate the genetic homogeneity of this condition. In the absence of any candidate gene, we undertook positional cloning of this gene. We identified, within the CADASIL critical region, the human Notch3 gene, whose sequence analysis revealed deleterious mutations in CADASIL families co-segregating with the affected phenotype. These data establish that this gene causes CADASIL. Identification of the CADASIL gene will provide a valuable diagnostic tool for clinicians and could be used to estimate the prevalence of this underdiagnosed condition. It should help in the understanding of pathophysiological mechanisms of CADASIL and vascular dementia.

What counts in brain aging? Design-based stereological analysis of cell number.

The advent and implementation of new design-based stereological techniques allows the quantification of cell number without the assumptions required when obtaining areal densities. These new techniques are rapidly becoming the standard for quantifying cell number, particularly in aging studies. Recently, studies using stereological techniques have failed to confirm earlier findings regarding age-associated neural loss. This newly emerging view of retained cell number during aging is having a major impact on biogerontology, prompting revaluation of long-standing hypotheses of age-related cell loss as causal for age-related impairments in brain functioning. Rather than focus on neuronal loss as the end-result of a negative cascade of neuronal injury, research has begun to consider that age-related behavioral declines may reflect neuronal dysfunction (e.g., synaptic or receptor loss, signal transduction deficits) instead of neuronal death. Here we discuss design-based stereology in the context of age-related change in brain cell number and its impact on consideration of structural change in brain aging. Emergence of this method of morphometrics, however, can have relevance to many areas of gerontological research.