Neurobehavioral deficits, histoarchitectural alterations, parvalbumin neuronal damage and glial activation in the brain of male Wistar rat exposed to Landfill leachate.

Concerns about inappropriate disposal of waste into unsanitary municipal solid waste landfills around the world have been on the increase, and this poses a public health challenge due to leachate production. The neurotoxic effect of Gwagwalada landfill leachate (GLL) was investigated in male adult Wistar rats. Rats were exposed to a 10% concentration of GLL for 21 days. The control group received tap water for the same period of the experiment. Our results showed that neurobehavior, absolute body and brain weights and brain histomorphology as well as parvalbumin interneurons were severely altered, with consequent astrogliosis and microgliosis after 21 days of administrating GLL. Specifically, there was severe loss and shrinkage of Purkinje cells, with their nucleus, and severe diffused vacuolations of the white matter tract of GLL-exposed rat brains. There was severe cell loss in the granular layer of the cerebellum resulting in a reduced thickness of the layer. Also, there was severe loss of dendritic arborization of the Purkinje cells in GLL-exposed rat brains, and damage as well as reduced populations of parvalbumin-containing fast-spiking GABAergic interneurons in various regions of the brain. In conclusion, data from the present study demonstrated the detrimental effects of Gwagwalada landfill leachate on the brain which may be implicated in neuropsychological conditions.

Cryptococcus neoformans seropositivity and some haematological parameters in HIV seropositive subjects.

BACKGROUND: Cryptococcus neoformans is an opportunistic fungal pathogen that causes meningitis worldwide and may be fatal in immunocompromised subjects. In Nigeria, cases have been reported with prevalence between 4 and 13.1% in Human Immunodeficiency virus (HIV) patients depending on the study subjects. This study was designed to assess the prevalence of cryptococcosis, CD4+T cell counts and possible effect on haematological parameters in HIV seropositive subject in Nnewi, South-Eastern Nigeria. METHOD: A total of four hundred and twenty-nine (429) subjects were recruited for the study. Of these, two hundred and ninety (290) were HIV positive and one hundred and thirty-nine (139) were HIV seronegative subjects recruited from the voluntary counseling and testing (VCT) unit and HIV care clinic at Nnamdi Azikiwe University Teaching Hospital Nnewi, Anambra State, Nigeria. Their ages were between 18-80 years. One hundred and thirty nine (139) apparently healthy HIV seronegative subjects were recruited as controls. Blood samples were taken for C. neoformans by Antigen lateral flow assay (CrAgLFA), HIV testing, CD4+T cell, platelet and Full blood count (FBC). RESULTS: Our results show that of the two hundred and ninety (290) who were HIV positive subjects investigated for cryptococcosis, 4 (1.4%) tested positive for CrAg of whom 1(25%) were male and 3(75%) were female. All those with cryptococcosis had their CD4 count below 200 cells/µL, three of them were on ART and one was not. There were significant differences in the CD4 counts (P<0.05) between those infected and not infected with C. neoformans. None of the control group tested positive to cryptococcosis. CONCLUSION: Widespread use of anti-retroviral therapy may have reduced C. neoformans infection. However, the threat remains and there may be a possibility that women may be a more vulnerable population.

Evolution, development, and initial function of the mammalian neocortex: response of the germinal zones to endothermy.

In the mouse the release of neocortical neurons from the periventricular germinal layers of the forebrain commences towards the ventral margin of the lateral pallium at the level of the interventricular foramen and is propagated from there across the lateral wall of the hemisphere. In the adult cortex the origin of the gradient corresponded to the ventral portion of the somatotopic map of the body, that is, to the area representating structures derived from the embryonic branchial arches, namely, the peri-oral region and laryngo-pharyngeal masticatory apparatus. Branchial arch nerves also innervate the fore- and mid-gut and all the related exocrine and endocrine glands. This suggests that the mammalian neocortex evolved from a visceral integration area in a positionally equivalent area in the pallium of a reptilian ancestor which expanded in relation to extensive changes taking place in the visceral and branchial systems of the body during the transition from reptilian ectothermy to mammalian endothermy. The practical problem facing early mammals was to acquire and process the extra energy required to sustain a continuously high metabolic rate. Improvements to the food processing capabilities of the visceral and branchial systems and the expansion of their neural control were important components in the conglomerate of changes required to sustain the increased energy demands of endothermic tissues. Endothermy also bestowed the ability to sustain greater numbers of metabolically expensive neurons and this, in turn, required an appropriate response from the cell production mechanisms in the periventricular germinal layers.

Modulation of the cell cycle contributes to the parcellation of the primate visual cortex.

An as-yet unresolved issue in developmental neurobiology is whether the discrete areas that form the mammalian cortex emerge from a uniform cortical plate or whether they are already specified in the germinal zone. A feature of the primate striate cortex is that the number of neurons per unit area is twice that of anywhere else in the cerebral cortex. Here we take advantage of this unique structural feature to investigate whether the extra striate cortical cells are due to increased neuron production during neurogenesis. We labelled precursors undergoing terminal cell division with 3H-thymidine and allowed them to migrate to the cortical plate. Cell counts revealed that their rate of production in the germinal zone of striate cortex is higher than in that given rise to extrastriate cortex. Also, we used 3H-thymidine pulse injections to investigate cell cycle dynamics and found that this phase of increased production of striate cortical cells is associated with changes in the parameters of the cell cycle. These results show that cortical area identity is at least partially determined at the level of the ventricular zone.

Experimental reproduction of the runting-stunting syndrome of broiler chickens.

A model for the reproduction of the runting-stunting syndrome (RSS) of broiler chickens is described. In this model, groups of at least 90 day-old broiler chickens were inoculated (per os) with various tissue homogenates or virus preparations. During the first week post-inoculation, birds were examined for the development of histopathological changes in their intestines. At day 14 post-inoculation, the remaining birds were weighed and tested for elevations in plasma amylase activity and examined for the development of pancreatic atrophy. Bacteria-free intestinal and pancreatic homogenates from chickens of different ages, taken from flocks which developed RSS, regularly induced a lower mean live-weight in treated birds. Of these, only intestinal homogenates prepared from 5-day-old birds induced intestinal lesions, lowered mean live-weight and increased the incidence of both elevated plasma amylase activity and pancreatic atrophy. These changes were more marked in birds exposed to short periods of sub-optimal temperatures during the first week post-inoculation. An ultracentrifuged pellet prepared from this intestinal homogenate, was also found to induce an increased incidence of pancreatic atrophy in treated birds. These studies suggest that the causative agent(s) of RSS is an as yet unidentified virus, and that the effects of this infection are greater in birds subjected to stress, such as sub-optimal temperature exposure, within the first week of hatch.

Antibodies to pollen exines.

A polyclonal antiserum and monoclonal antibodies have been prepared to purified pollen exines of Calocedrus decurrens Florin. The location of the antigen is in the exine, as shown by light-and electron-microscopic immunocytochemistry. The greatest reduction in antibody binding follows treatment of the exine with chemicals known to alter sporopollenin. These results provide evidence that sporopollenin is antigenic. Exines of ten species of gymnosperms and angiosperms also bound the polyclonal antiserum, indicating similarity of sporopollenin structure.

The application of the ELISA to the diagnosis and control of avian encephalomyelitis.

An ELISA for measuring serum antibody against avian encephalomyelitis virus (AEV) was evaluated for its application to the diagnosis and control of avian encephalomyelitis (AE). A scoring system was developed for this ELISA (AE ELISA-Index) so that the overall level of antibody in the flock could be presented in a single, convenient number. During suspected outbreaks of disease thought to have been caused by AEV infection, the AE ELISA-Index increased in sequential serum samples. High levels of antibody against AEV were measured in 13 flocks experiencing egg productivity problems. Variable levels of antibody activity against infectious bronchitis virus (IBV) were also observed in 11 of these flocks. The AE ELISA-Index was correlated with the embryo susceptibility test. Application of the AE ELISA has indicated that natural exposure to the virus does not occur in all flocks, and vaccination failures were detected sufficiently early for revaccination to be administered before the onset of lay.

Gyrus formation in the cerebral cortex of the ferret. II. Description of the internal histological changes.

The internal changes within a developing gyrus of the ferret cerebral cortex were studied by recording (i) the changing length and direction of the radial tissue lines and (ii) the emergence of the tangential banding of the classical six cortical layers. Together these lines provided a coordinate net whose deformations during development gave an indication of the differential growth occurring within a gyrus. The changes in these features suggested that a gyrus was initiated by an area of local growth appearing in the subplate and then in the suprajacent segment of cortical plate. During subsequent growth there was tangential spreading of the more mature tissue at the gyral crown while at the site of the future sulci the cortical plate remained immature and growth was retarded. During later stages the majority of tangential growth occurred in the parasulcal area. At this site a very much thinner cortex was generated from a segment of cortical plate of the same depth and degree of nuclear crowding as elsewhere, implying that growth here was resolved into tangential spreading. The cells and fibres of the deeper cortical layers of the sulcal cortex eventually became tangentially orientated suggesting that they subserved a commissural function between the columnar systems of adjacent gyri. At the scale prevailing in the ferret, gyrus formation was seen as a configuration which tended to conserve both the total length of the cortical columns and the depth of the individual cortical layers.

Immunofluorescent screening of monoclonal antibodies to surface antigens of animal and plant cells bound to polycarbonate membranes.

We have developed an immunofluorescent screening method in which animal or plant cells are immobilized without fixation on polycarbonate (Nuclepore) membranes. The technique does not involve centrifugation, and virtually no cells are lost during processing. Direct microscopic analysis of antibody binding provides an extremely sensitive and reproducible screening system for hybridoma supernatants.

Gyrus formation in the cerebral cortex in the ferret. I. Description of the external changes.

The external features of gyrus formation in the postnatal ferret cerebral cortex are described and correlated with certain internal changes. The observations indicate that gyri are formed by longitudinal and radial expansion of the cortical compartment occurring between relatively fixed areas which form the sulcal floors. The gyri were initially rounded with open sulci and the cerebrum had a rectangular outline when seen in lateral and dorsal view. By adult life the hemisphere had been subjected to considerable moulding by the growing skull, so that the frontal pole of the cerebrum became pointed while the sulcal walls became closely opposed and the gyral crowns flattened.

Cell production gradients in the developing ferret isocortex.

The accumulation of cells within the cortical plate was studied in ferrets at two developmental ages. A survey method based on the presumed radial organisation of cortical neuron production was used to sample variations in cell production along the rostrocaudal and laterodorsal axes of the brain. The resulting cell counts confirmed the presence of a gradient of cortical plate formation, with a rostrolateral focus. These findings were discussed in relation to some recent teratological studies on brain development in ferrets, where there has been a lack of normative data.

Absence of a role for selenium deficiency in the runting syndrome of broiler chickens in Australia.

The role of selenium deficiency in the etiology of the runting-stunting syndrome (RSS) of broiler chickens in Australia was investigated. Commercial broiler chickens maintained on selenium-deficient developed signs consistent with selenium deficiency of exudative diathesis and markedly reduced plasma glutathione peroxidase activity, but they did not develop pancreatic atrophy and fibrosis or elevated plasma amylase activity, which are the other lesions associated with RSS. Supplementation of the diets of birds from a RSS-susceptible flock with a mixture of selenium, vitamin E, cysteine, and sulfate had no effect on the incidence of runting in the treated birds. In field outbreaks of RSS there were no observable differences between affected and unaffected birds in the concentration of selenium in tissue samples. Furthermore, evidence is presented which suggests that in cases of RSS, pancreatic atrophy and elevations in plasma amylase precede reductions in plasma glutathione peroxidase activity.

Enzyme-linked immunosorbent assay for determining specific immunoglobulin M in infections caused by Leptospira interrogans serovar hardjo.

An automated enzyme-linked immunosorbent assay detecting specific immunoglobulin M in infections with Leptospira interrogans serovar hardjo was evaluated on 69 patients. The test was sensitive and simple to perform, requiring a single dilution of test serum, with data expressed as units of antibody activity interpolated from a reference serum pool.

Differential growth of the cell production systems in the lateral wall of the developing mouse telencephalon.

Three major cell production systems were identified in the lateral wall of the mouse telencephalon. These were morphologically evident as the medial and lateral elevations and the pallial crescent. Each was originally derived from a small, circumscribed, subset of ventricular cells. These formed the parent populations of large and proliferatively complex precursor pools which gave rise to the large numbers and considerable variety of neuron populations of the telencephalon. An attempt was made to identify the major neuron groups derived from each system by using the ventricular cell processes as a guide to the site of neuron origin. The proliferative changes occurring in the two elevations, the variety of their neuronal output, the early loss of a radial structure and the diversity of the final adult configurations were considered to represent a more complex series of changes than the corresponding events in the cortical tissue, which was generated from the pallial crescent where neurons accumulate within an adaptation of the original radial structure. It was considered that the number and complexity of the changes in the genome required to produce and organise such subcortical diversity was of a greater order of magnitude than those evident in the cortical areas. It was suggested that the genesis of the mammalian basal telencephalon should be considered as one of the major evolutionary achievements in the conglomerate of changes which occurred during the transition from the reptilian to the mammalian grade of organisation in the forebrain.

Measurement of antibodies to infectious avian encephalomyelitis virus by ELISA.

An enzyme-linked immunosorbent assay (ELISA) for the measurement of antibody to avian encephalomyelitis virus (AEV) is described. The wells of microtitre trays were coated with antibody to AEV, to which was bound a partially purified AEV preparation as an immunosorbent. The assay described is specific, in that antibody activity was not detectable in specific-pathogen-free (SPF) chickens except following inoculation with AEV. Inoculation of SPF chickens with a number of other viruses did not induce a detectable response. Furthermore, there was agreement between the ELISA and virus neutralisation test in terms of the rank order of a number of test sera and in the positive/ negative classification of sera. Both ELISA and virus neutralisation were capable of detecting an antibody response within 9 days of primary vaccination indicating that the ELISA was of comparable sensitivity to virus neutralisation. The amount of antibody in a sample was estimated relative to a reference serum preparation, and the results recorded as units of antibody activity. Using this method of data expression it has been possible to demonstrate that these assays are reproducible with little within-assay (co-efficient of variation = 5.6%) or between-assay (co-efficient of variation = 9.8%) variation for the mid-range sample.

A localised growth zone in the wall of the developing mouse telencephalon.

In sections of the prenatal mouse brain, sites of maximum area increase of the lateral ventricle were mapped onto reconstructions of the ventricular surface. This was done by identifying areas of ventricular layer where mitotic density was high and the adjacent intermediate layer either absent or thinly populated with neurons. It was assumed that in these areas, cell division was producing ventricular cells rather than neurons and that they were therefore gaining in area, whereas sites against which neurons were accumulating were either ceasing to increase in area or at least were increasing more slowly. Such an area occupied a zone at the junction between the medial and lateral telencephalic walls. The zone was eliminated during development in a rostrocaudal direction. It is suggested that modulation of growth along this zone may be an important factor in fashioning the form of the ventricular cavity.

Pancreatic degeneration in broilers with runting and stunting syndrome.

A number of plasma biochemical parameters were examined in five outbreaks of runting in broiler chickens. In four of the five outbreaks, runts showed consistent elevations in plasma amylase activity and reductions in glutathione peroxidase activity. In two of the five outbreaks the plasma vitamin E concentration was reduced, as was the activity of plasma alkaline phosphatase. A highly significant number of runted chickens were found to have pancreatic degeneration, elevated plasma amylase activity and reduced plasma glutathione peroxidase activity, compared with non-runted chickens. The implications of these changes are discussed in relation to the aetiology of runting and stunting syndrome and, in particular, the possible involvement of selenium.

Histogenesis of the mesocortical area of the mouse telencephalon.

The histogenesis of the mesocortex of the mouse telencephalon was studied by plotting the progress of neuron release on reconstructions of the medial pallial wall. Histological changes were correlated with cell birth date using data obtained from autoradiographs of mice pulse-labelled with tritiated thymidine during the prenatal period of neuron birth. It was found that neuron release for this area began rostrally at about E12-E13 and spread rapidly from this origin in a caudal direction across the medial wall. Neurons accumulating in the intermediate layer were at first more or less equally spaced. About E14, neurons in the outer intermediate layer began to line up to form a 'mesocortical plate'. This plate was formed from older nuclei and therefore overlay a deeper intermediate layer composed of younger cells. The mesocortex continued to develop by progressive withdrawal of younger cells from the deep intermediate layer into more superficial layers of the definitive cortex. In most of the mesocortical area, however, this original pattern was superseded by release of neuron generations which migrated directly to the outer intermediate layer to form a plate of densely packed immature neurons. This population was continuous with a similar population forming the isocortical plate of the lateral telencephalic wall. It was postulated that the wave of neuron birth and release which gave rise to the isocortical plate was propagated beyond the isocortical boundary into mesocortical territory as far as the boundaries of the subiculum, indusium griseum and anterior hippocampal rudiment.