Diffuse pollution associated with the mining sectors in South Africa: a first-order assessment.

Internationally it has become recognised that diffuse source water pollution from mining activities severely affects the degradation of water quality especially with regards to acidification and metal loading. South Africa is facing major problems with regard to the management and treatment of contaminated mine water. Very little has been published for South Africa about the quantities and qualities of diffuse source water pollution by the mining industry. Furthermore the available information has not yet been compiled into a consolidated overview that presents the total picture. Some of the problems that limit the use of the available information and would necessitate further processing to normalise the data, derive from the fact that the investigations producing the information were done at different times, to different levels of detail and using different approaches. A further complicating factor is that data for some mining commodities may not be available and may necessitate further investigation. The overview of the quantities and qualities of non-point source effluent production by different sectors needs to be interpreted in terms of the effect the effluent can be expected to have on receiving water quality (both surface and groundwater). It would thus be necessary to categorise waste types according to their effect on water quality and synthesise the data to obtain an estimate of the threat that different sectors and sub-sectors pose to receiving water quality.

Assessment of point and non-point pollution associated with the power generation sector in South Africa.

Access to water and water availability remains a key factor in ensuring the sustainability of development in Southern Africa. The need for guidelines to improve management of this valuable resource, and to regulate pollutant discharge, is therefore of national interest. A new and growing threat to our natural water resources is non-point source (NPS) pollution. The important distinction between point pollution and NPS pollution is that the latter is difficult to identify and the entry point of contamination to resources is diffuse and not limited to a single location. NPS pollution associated with power generation includes, but is not limited to, atmospheric deposition resulting from emissions (air and water), leachate from coal storage piles and runoff from impervious areas which are covered with dust fallout from coal and ash handling operations. Emissions of primary concern are sulfur, nitrogen and mercury.

Chemical characterisation of organic electron donors for sulfate reduction for potential use in acid mine drainage treatment.

The production of acid mine drainage (AMD) containing high amounts of sulfate, heavy metals and low pH is of increasing concern. AMD is highly corrosive and results in economic and environmental problems. Organic electron donors for sulfate reduction were chemically characterised for potential use in AMD treatment. This was done in a process to develop a correlation between chemical composition and the capacity to drive sulfate reduction. Potential organic electron donors for sulfate reduction were chemically characterised in terms of dry matter content, ash content, total Kjeldahl nitrogen, lignin content, cellulose content, crude fat, crude fibre, in vitro digestibility, water-soluble carbohydrates, total non-structural carbohydrates and starch content. The chemical composition of the organic electron donors was then compared to results obtained from pilot plant studies where the organic electron donors for sulfate reduction were evaluated in terms of sulfate reduction. The chemical composition of the carbon source severely impacted its capacity to drive sulfate reduction and may be used to assist in predicting the sulfate reduction capacity of a carbon source. Organic electron donors for sulfate reduction high in protein content and low in lignin content or high in carbohydrate and crude fat content increased the capacity of a carbon source to drive sulfate reduction. The higher the fibre content of a carbon source, the lower the capacity to drive sulfate reduction. No correlation could be drawn between % dry matter, % ash content and sulfate reduction for the organic electron donors tested. Chemical characterisation can be used to assist in predicting sulfate reduction capacity of organic electron donors.

[Cortico-subcortical electrophysiological study during the effects of benzodiazepines in patients with panic disorders]. / Estudio electrofisiológico córtico-subcortical durante los efectos de benzodiacepinas en pacientes con trastornos de pánico.

INTRODUCTION: Tribute to Robert Heath, M.D. a pioneer in human implanted corticosubcortical microelectrodes. OBJECTIVES: We evaluate retrospective electroencephalography (EEG), local evoked potentials (LEP) and extracellular unitary activity (EUA) of patients with diagnosis of panic disorder in association of simple partial seizures. These patients had presences or absence of agoraphobia. They received treatment with clonazepam or diazepam. PATIENTS AND METHODS: Ten patients with implanted corticosubcortical were divided in two groups. The five patients of group A were treated with clonazepam and the five patients of group B with diazepam. RESULTS: Panic attacks showed EEG thetha activity, increased amplitude of the negative phase of LEP, and an increase in the frequency of EUA in cortico-subcortical organizations. This changes occurred in all organizations with exception of the inhibitory reticular substance. Panic disorder produced abundance of repetitive epileptiform discharges that could precipitate convulsive crisis. Both benzodiazepines were efficacious although results with clonazepam were observed earlier: at 7 to 14 days. Benzodiazepines increased corticosubcortical EEG beta activity, decreased amplitude of negative phase of LEP, and diminution in the frequency of EUA. This changes occurred with exception on the inhibitory reticular system. We postulate: a) That panic disorder hyperexcitability at the cortico-subcortical neuronal level may be the result of gabergic dysfunction, or alteration in neuroinhibitory mechanism through GABAA receptors, and through GABAB neuromodulator receptors, and b) That there is a direct correlation between GABA inhibitory basic mechanism and electroencephalographic beta activity. CONCLUSIONS: Panic disorder produces neuronal hyperexcitability by gabergic dysfunction both benzodiazepines were efficacious in treatment.

Antiretroviral antibodies: implications for schizophrenia, schizophrenia spectrum disorders, and bipolar disorder.

BACKGROUND: Some retroviral antigens share structural homology within a group of related retroviruses. It is possible that antibodies directed against one virus may cross-react with antigens from a different virus in the group. METHODS: Using this principle, the human immunodeficiency virus 1 (HIV-1) Western blot assay was used as an available source of human retroviral antigens to screen serum samples from an archived collection to ascertain whether there was an association between serum antiretroviral antibodies and mental illnesses. RESULTS: A statistically significant proportion (28/54, 52%) of patients suffering from psychiatric disorders had serum antibodies that recognized at least one antigen present on the blot, culminating in indeterminate HIV-1 tests. The majority of the reactive samples were directed against the HIV-1 group antigens p24 and p17. These findings contrast with those of nonpsychiatric patients, who had 4/16 (25%) indeterminate blots. CONCLUSIONS: The results suggest exposure to retroviral antigens related to those of HIV-1 in subpopulations of schizophrenic, schizophrenic spectrum disorder, and bipolar disorder patients.

Antiseptal brain antibody in IgG of schizophrenic patients.

On the hypothesis that schizophrenia is an immunological disorder in which antibody is produced against a unique antigen sequestered principally or exclusively in the septal region of the brain, we used crossed-immunoelectrophoresis (CIE) to evaluate reactivity of a gamma G immunoglobulin (IgG) fraction from serum of schizophrenic patients and nonschizophrenic control subjects with homogenates of tissues of septal region, hippocampus, vermal cerebellum, frontal cortex, and liver of rhesus monkeys. When IgG fractions of unmedicated schizophrenic patients and schizophrenic patients who had received neuroleptic medication for less than 24 hr were tested against septal region homogenate, a precipitin arc was identified, indicating a positive result, with more than 95% of the fractions. In contrast, IgG fractions of schizophrenic patients who had received neuroleptic medication for more than 24 hr were rarely positive. When schizophrenic fractions that tested positive against septal region homogenate were tested against homogenates of the other tissues, they were negative. Fractions of all nonschizophrenic control subjects were negative against all homogenates.

Kappa opiate receptor agonists: effects on behavior and on brain function and structure in rhesus monkeys.

In the present study several drugs that are predominantly agonists of kappa receptors were tested in rhesus monkeys prepared with deep and surface brain electrodes. The administration of two benzomorphan derivatives and of ethylketocyclazocine induced acute behavioral effects resembling catatonia concomitant with generalized spike and slow-wave electroencephalographic activity at widespread brain sites, that lasted for about 1 hr. After administration of one to three doses of these agonists (the benzomorphan derivatives to five monkeys and the ethylketocyclazocine to two monkeys), chronic recording changes developed, characterized by continuous high-amplitude spiking activity focal at the anterior septal region and periaqueductal gray of the mesencephalon. They increased in intensity with the passage of time, the monkeys having been followed as long as 5 months without further drug administration. Light microscopy and electron microscopy showed no structural abnormalities in the monkey brains at the sites of altered recordings, although occasional dendritic atrophy was noted at all cortical and subcortical brain sites examined. Chronic recording changes did not develop in a monkey that received U-50,488H on eight occasions. And none of the electrode-implanted monkeys that served as controls (having received no kappa agonists) developed recording changes. The sites affected by the active kappa agonists were those at which abnormal activity has been correlated with psychotic behavior. The ability of the kappa agonists to induce a lasting physiologic change without corresponding structural change at those focal sites implicated in schizophrenia may prove a useful probe in further investigations into the cause of schizophrenia and its ultimate treatment.

Subcortical EEG changes in rhesus monkeys following experimental hyperextension-hyperflexion (whiplash).

A controlled study, involving EEG recordings from the scalp and chronically implanted electrodes in the cortex (ECoG), as well as from selected subcortical nuclei, was undertaken to investigate the neurophysiologic effects on rhesus monkeys following experimental whiplash (hyperextension of the head and neck). Sixteen animals, equally divided into four groups, were studied through the following protocol: (1) two animals within each group were whiplashed and then electrodes were implanted into the brain of one; (2) the second two animals were implanted with deep electrodes and then one was whiplashed. Weekly EEG follow-ups showed hippocampal spiking in three of the four whiplashed and then electrode-implanted animals and in one of implanted and then whiplashed animals 6 to 8 weeks postwhiplash. Several results deserve attention. (1) The "whiplash syndrome" owes part of its symptoms to EEG disturbances in the brain. (2) Prior to the onset of spiking, ie, 6 to 8 weeks postwhiplash, practically all scalp, cortical, and subcortical EEG recordings were normal. (3) When hippocampal EEG spiking did take place, only normal and mildly abnormal changes were seen in either the electrocorticogram (ECoG) or scalp electroencephalogram (EEG). (4) The growth and development of this trauma-induced hippocampal spiking followed the classic sequence for the spread of an epileptogenic focus. (5) This apparent subclinical form of posttraumatic epilepsy may be due to the combined effects of the whiplash plus the subcortical electrode placements further decreasing the already well-known, low-spiking threshold of the hippocampi.

Finite element analysis of current pathways with implanted electrodes.

A technique for numerical solution to complex electric field distribution problems has been devised. The specific application for which it was developed is the analysis of current density and isopotential line spacing from implanted neurostimulation electrodes. Three configurations of cerebellar stimulation electrodes in clinical use were studied for current spread to regions distant from the cerebellum using a planar model of the human head, neck, and upper torso in mid-saggital section. It was found that an array of cathodes on the superior cerebellar surface and an array of anodes on the inferior cerebellar surface causes significant current spread to the brainstem, a prediction confirmed by clinical observation in patients with previously implanted electrodes of this configuration. Results modelling other electrode configurations are also presented, along with a study of the effects of possible inaccuracies in available impedance data for neural tissue.