Spatial distribution of iron oxidation in the aerobic cells of the Wheal Jane Pilot Passive Treatment Plant.

The wetland cells of the Wheal Jane Pilot Passive Treatment Plant (PPTP) were designed to promote aerobic oxidation and precipitation of iron which could exceed a concentration of 100 mg l-1 in the raw mine water. The largest investment of land area was to the wetland (also called aerobic) cells and it was important to understand the processes of oxidation and precipitation of iron so that the performance of this part of the pilot passive treatment plant (PPTP) could be managed efficiently. The results of a high-resolution sampling programme on the distribution of Fe(II) within the first wetland cell of each treatment system are described. Comparison of inflow and outflow concentrations of iron adequately described the performance of the lime-dosed (LD) system. However, precipitation of iron in the anoxic limestone drain (ALD) and lime-free systems (LFS) was more efficient. On average, about 90% of the iron present in the inflow was removed using only 50% and 33% of the first aerobic cells of the ALD and LFS systems, respectively. As the concentration of iron approached 20 mg l-1, the rate of oxidation slowed considerably. This was probably due to be due to low pH levels caused by hydrolysis of Fe(III). With the introduction of passive pH control mechanisms, there was capacity to increase the volume of mine water treated by the ALD and LDS systems by 10 and 15 times, respectively, but it is uncertain as to whether or not other aspects of the passive treatment system would have sufficient capacity to deal with the increased volumes of mine water.

Effects of nicotine and tobacco smoke on the electrical activity of the cerebral cortex and olfactory bulb.

1. Effects of nicotine, cigarette smoke and carbon monoxide have been compared in the cat encéphale isolé preparation, exhibiting a synchronized electrocorticogram (ECoG) and behavioural sleep.2. 2 ml samples of smoke, containing approximately 7 mug nicotine (approximately 2 mug nicotine/kg for a 3 kg cat), introduced into the lungs at 30 s intervals from a smoking simulator, caused desynchronization of the ECoG and behavioural arousal.3. Effects of smoke were matched in the same experiments by intravenous injections of nicotine, 2 mug/kg every 30 s.4. The use of specific nicotine antagonists, for example mecamylamine, and filters for removing nicotine, indicated the presence in smoke of other agents capable of exerting a pharmacological response.5. Cigarette smoke contains approximately 5.0% carbon monoxide. Introduced into the lungs of cats pretreated with mecamylamine (2 mg/kg), 2 ml samples of 5% carbon monoxide caused changes in the ECoG similar to those caused by smoke.6. Effects of nicotine or smoke were not modified by pretreatment with chlorpromazine (2.0-4.0 mg/kg). Atropine (0.3 mg/kg), however, prevented the cortical activation, but not the behavioural arousal.7. 2 ml samples of smoke applied to the nostrils caused the occurrence in the olfactory bulb of a discharge or burst of "induced" waves. This discharge was sometimes accompanied by a transient period of cortical activation.8. These studies demonstrate that in cats, nicotine is the principal pharmacological constituent of tobacco smoke as far as effects on the central nervous system are concerned, although other constituents of smoke may play a contributory role.

Changes in body temperature produced by cholinomimetic substances injected into the cerebral ventricles of unanaesthetized cats.

1. The effects on body temperature of a number of substances injected into a lateral cerebral ventricle were examined in the unanaesthetized cat.2. Nicotine (50 and 100 mug) caused a fall in body temperature ranging from 0.95-2.1 degrees C associated with skin vasodilatation, tachypnoea and panting. These responses were prevented by the intraventricular injection of hexamethonium or mecamylamine, but not of atropine or phentolamine.3. Carbachol (5 mug) caused a rise in temperature associated with skin vasoconstriction, piloerection and severe shivering. These effects were prevented by the intraventricular injection of atropine, but not of hexamethonium or mecamylamine.4. An acetylcholine/eserine mixture (10 mug of each) had no reproducible effect on body temperature. Because of the variability in the response, interaction studies with antagonist drugs were not performed.5. Hexamethonium (100 mug) or mecamylamine (100 mug) caused a prolonged rise in temperature, together with skin vasoconstriction, piloerection and intense shivering. Atropine (200 mug) was without effect on body temperature.6. Noradrenaline (100 mug) caused a fall in temperature with skin vasodilatation. The fall was converted to a rise with skin vasoconstriction, piloerection and vigorous shivering following an intraventricular injection of phentolamine (100 mug).7. These observations suggest the existence of cholinergic heat loss and heat gain mechanisms in the hypothalamic thermoregulatory pathways of the cat and the interaction studies with hexamethonium, mecamylamine and atropine, support the involvement of ;nicotinic' and ;muscarinic' receptors within the cholinergic thermoregulatory system.

Effects of nicotine on electrocortical activity and acetylcholine release from the cat cerebral cortex.

1. The effects of small amounts of nicotine on electrocortical activity and central acetylcholine (ACh) release have been studied on anaesthetized cats.2. The most common effect of nicotine given intravenously in a dose of 2 mug/kg every 30 sec for 20 min was to cause desynchronization of the electrocorticogram, indicating cortical activation, and an increase in the release of cortical ACh.3. A larger dose given less frequently (4 mug/kg every min for 20 min) caused, in some experiments, an increase and in others a decrease in cortical activity. Such changes were accompanied respectively by an increase or decrease in cortical ACh output.4. The amounts of nicotine that affected the electrocorticogram and ACh release are probably similar to those absorbed by the cigarette smoker who inhales.5. The effects of nicotine on the electrocorticogram were transient, but the effects on ACh were prolonged. This suggests that at least two pathways are involved in the nicotine response.

Copper toxicity: evidence for the conversion of cupric to cuprous copper in vivo under anaerobic conditions.

We have determined the toxicity to cells of Escherichia coli B of cupric copper applied under aerobic and anaerobic conditions in two ways. The growth of cells in liquid medium incorporating cupric copper shows differential inhibition, comparing aerobic and anaerobic conditions--toxicity being greater under anoxia. The growth of colonies upon agar plates incorporating cupric copper does not show such a differential effect. We conclude that colonies on plates are largely anoxic even when incubated aerobically. EPR spectra of cells obtained at various times after application of cupric copper under anoxic conditions indicate the conversion of a considerable proportion of the Cu(II) to a non-paramagnetic species, probably Cu(I). We demonstrate that Cu(I) is more toxic than Cu(II) to cells when applied under anoxic conditions and conclude that the difference in toxicity of Cu(II) applied to cells under aerobic and anaerobic conditions results from the greater extent of reduction of Cu(II) to Cu(I) under anaerobic conditions.

Frequency of attendance in general practice and symptoms before development of chronic fatigue syndrome: a case-control study.

BACKGROUND: Chronic fatigue syndrome (CFS) research has concentrated on infective, immunological, and psychological causes. Illness behaviour has received less attention, with most research studying CFS patients after diagnosis. Our previous study on the records of an insurance company showed a highly significant increase in illness reporting before development of CFS. AIM: To investigate the number and type of general practitioner (GP) consultations by patients with CFS for 15 years before they develop their condition. DESIGN OF STUDY: Case-control study in 11 general practices in Devon. SETTING: Forty-nine patients with CFS (satisfying the Centers for Disease Control criteria), 49 age, sex, and general practice matched controls, and 37 patients with multiple sclerosis (MS) were identified from the general practices' computerised databases. METHOD: The number of general practice consultations and symptoms recorded in three five-year periods (quinquennia) were counted before development of the patients' condition. RESULTS: The median number of consultations was significantly higher for CFS patients than that of matched controls in each of the quinquennia: ratios for first quinquennium = 1.88, P = 0.01; second quinquennium = 1.70, P = 0.005; last quinquennium = 2.25, P < 0.001. More CFS patients than controls attended for 13 of the 18 symptoms studied. Significant increases were found for upper respiratory tract infection (P < 0.001), lethargy (P < 0.001), and vertigo (P = 0.02). Similar results were found for CFS patients when compared with MS. CONCLUSIONS: CFS patients consulted their GP more frequently in the 15 years before development of their condition, for a wide variety of complaints. Several possibilities may explain these findings. The results support the hypothesis that behavioural factors have a role in the aetiology of CFS.

Effects of beach sand properties, temperature and rainfall on the degradation rates of oil in buried oil/beach sand mixtures.

Lysimeters located outdoors have been used to evaluate the decomposition of buried oily beach sand waste (OBS) prepared using Forties light crude oil and sand from different locations around the British coast. The OBS (5% oil by weight) was buried as a 12-cm layer over dune pasture sub-sand and overlain by 20 cm of dune pasture topsoil. Decomposition rates of oil residues averaged 2300 kg ha(-1) in the first year and the pattern of oil decomposition may be represented by a power curve. Oil decomposition was strongly related to the temperature in the OBS layer, but was also significantly affected by rainfall in the previous 12 h. The CO(2) flux at the surface of the treatment lysimeters followed the relationship [log(10) CO(2) (mg C m(-2) h(-1))=0.93+0.058x OBS temp. (degrees C)-0.042x12 h rain (mm)]. There was considerable variation in the rate of oil decomposition in sands collected from different sites. Sand from Askernish supported most microbial activity whilst sand from Tain was relatively inactive. The decomposition process appeared to cease when the sand became saturated with water, i.e. temporarily anaerobic. However, decomposition recommenced when the soil dried out. The fastest rate of decomposition occurred in sand from one of the two sites predicted to have high populations of hydrocarbon-degrading bacteria. Larger particle size and higher Ca content may also be significant factors governing the rate of decomposition.

A comparison of methods for nasal mast cell demonstration.

Nasal turbinates were studied from 14 rhinitis patients following surgical turbinectomy, and from five subjects at autopsy. Mast cell counts on turbinectomy specimens were compared following staining with toluidine blue or Alcian blue and safranin after fixation in either paraformaldehyde or neutral buffered formalin. Mast cell numbers were significantly greater in the superficial submucosa than in the epithelium or deep submucosa in both the rhinitis group and the autopsy subjects. The combination of PFA fixation and ABS staining gave maximum mast cell counts, revealed two morphological mast cell sub-types and gave optimal demonstration of nasal tissue. Nasal mast cells are thus not uniformly distributed, appear heterogeneous under light microscopy, are present in large numbers even in the elderly, and are best demonstrated using PFA fixation and ABS staining.