Halting the upward trend in soluble phosphorus transported from a grassland catchment.

An upward trend in soluble reactive phosphorus (SRP) concentrations in Northern Ireland rivers leading to increased eutrophication has been reported for the last two decades. To identify if a similar trend could be observed in land drainage waters SRP and other P fractions were measured weekly from 1989 to 1997 in land drainage from a 9-ha grassland catchment in Northern Ireland that had a mean P surplus applied of 23.4 kg P ha(-1) yr(-1). Regressions of annual median concentrations of P fractions in land drainage waters against time for 1989 through to 1997 showed significant increases of SRP and soluble unreactive phosphorus (SUP) of 2.4 and 1.2 microg P L(-1) yr(-1), respectively. However, the annual flow-weighted concentrations and loads of all P fractions did not show significant increases with time. During the period 1998-2000 a change of management was introduced when only maintenance dressings of P were applied to the catchment according to Ministry of Agriculture, Fisheries and Food guidelines. This resulted in significant reductions in SRP concentrations in 2000 compared with 1997.

Changing perspectives on the importance of urban phosphorus inputs as the cause of nutrient enrichment in Lough Neagh.

The scale and chronology of the phosphorus (P) enrichment of Lough Neagh, a large hypertrophic lake, was assessed using, as enrichment proxies, published palaeocological studies on diatoms and chironomid head capsules preserved in the lake sediments and, from 1974, monitoring data from the lake and its inflowing rivers. Enrichment commenced in 1880, and the scale and chronology of the diatom and chironomid records were similar up to 1960, but in the 1960s, chironomid accumulation rates increased dramatically, whereas diatom rates remained unchanged. From subsequent lake monitoring, the absence of a diatom response after 1960 was attributed to silica limitation so that P could be considered as the driver of increased diatom production only up to 1960. Using a coefficient for the demand for P by diatoms of 4 microg P mg SiO(2)(-1), it was calculated that the increased diatom production between 1881 and 1961 required an increase in lake P of 26 microg P l(-1). This value is close to the predicted increase of 22.5 microg P l(-1) in the lake caused by inputs of P from sewage treatment works and septic tanks. There was no evidence that diffuse source P contributed to enrichment over this period. Enrichment up to 1960 appears modest in comparison to subsequent years. From 1961 to 1974, lake P was estimated to have increased by 62 microg P l(-1), but only 25 microg P l(-1) of this increase was attributable to greater loadings of P from urban and septic tank sources. The enrichment response of chironomids at this time was also much greater than expected from a regression-derived relationship between urban P inputs and chironomid accumulation rates suggesting additional sources of P. The larger than expected increase in lake P was attributed to the onset of a significant internal loading of P and the commencement of an increase in diffuse source loadings of P. River monitoring has shown that diffuse P has increased steadily since 1974, more than counterbalancing a 40% reduction in urban P loadings that has taken place since 1980. By the end of the 20th century urban sources contributed only 19.7% of inflow P to Lough Neagh but lake P was 145 microg P l(-1) compared to an estimated concentration of 20 microg P l(-1) in 1881. Failure to control diffuse P sources has therefore been instrumental in the continued increase of lake P in Lough Neagh.

Fertility of dairy cows in Northern Ireland.

A comprehensive database was established on the milk production and reproductive performance of dairy cows in 19 selected herds in Northern Ireland, varying in size, management system and genetic merit. Data were obtained for 2471 cows, 1775 of which calved in a second year, and 693 were culled from the herd for specific reasons. The estimated mean rate of heat detection (assessed by the interheat interval during the main breeding season) in all the herds was 71 per cent, with a range from 53 to 92 per cent The average conception rate to first insemination was 37.1 per cent (range 21 to 66 per cent). The average calving interval for the retained cows was 407.2 days (range 359 to 448 days). Twenty-eight per cent of the cows that calved were culled, with infertility being the largest single reason (26.8 per cent of the cows culled). There were major differences in reproductive performance between the herds, but heat detection rate, conception rate and calving interval did not appear to be affeded by a herd's genetic merit. The herds with shorter calving intervals were characterised by better heat detection efficiency (83 v 61 per cent, P<0.01), a shorter interval from calving to first insemination (74 v 97 days; P<0.05), a higher conception rate to first insemination (45 v 34 per cent, P>0.10) and a lower removal rate (23 v 37 per cent, P<0.01). Furthermore, the cows in these herds had lower body condition scores (BCS) in the dry period (3.0 v 3.3; P<0.05) but lost less body condition in early lactation (0.3 v 0.6 BCS units, P<0.05). These results show that dairy herd fertility in Northern Ireland is generally low and similar to that previously reported for England and the USA, but that in some herds changes in herd management practices improved the cows' fertility.

Assessing the effectiveness of regulatory controls on farm pollution using chemical and biological indices of water quality and pollution statistics.

Water quality was measured in 42 streams in the Colebrooke and Upper Bann catchments in Northern Ireland over the period 1990-1998. Despite ongoing pollution control measures, biological water quality, as determined by the invertebrate average score per taxon (ASPT) index, did not improve and there was no appreciable decline in recorded farm pollution incidents. However, the lack of decline in pollution incidents could reflect changes in detection policy, as a greater proportion of incidents were recorded from less polluting discharges such as farm-yard runoff. In contrast, there was an improvement during 1997 and 1998 in annual chemical water quality classification based on exceedence values (90th percentiles) for dissolved oxygen, ammonium and BOD concentrations. In 1998, 11.9% of streams were severely polluted compared to 26.2% in 1990, while the proportion classed as of salmonid water quality, increased from 40.5% in 1990 to 59.6% in 1998. Although water quality in 1996 did not improve relative to 1990 values, there was a notable increasing trend from 1990 in the numbers of samples taken during the summer which had good water quality with low ammonium (<0.6mgN l(-1)) and high dissolved oxygen (> 70% sat). The trend for samples with low BOD (<4 mgl(-1)) was more erratic, but an improvement was apparent from 1994. These improvements in chemical water quality suggest that point-source farm pollution declined after 1990. The fact that this was not reflected in stream biology may reflect the limited time scale for biological recovery. An important factor preventing biological recovery may be the high pollution capacity of manures and silage effluent, so that even reduced numbers of farm pollution incidents can severely perturb stream ecosystems. The intractable nature of farm pollution suggests that there is a need to consider an interactive approach to problem resolution involving both farmers and regulators.

The importance of catchment and lake processes in the phosphorus budget of a large lake.

Total phosphorus (P) river inputs and lake concentrations for the Neagh system in Northern Ireland are compared from the period 1974-1997. The main routes of P transfer between the lake water and the sediment are settlement of abiotic particles and planktonic diatoms, summer sediment release and re-sedimentation in the last months of the year. The annual river loading to the lake varied between 0.7 and 1.8 g P m(-2), and sediment release can be as much as 1.4 g P m(-2). A simple model evaluated the effect of sediment-water exchanges on the phosphorus available for spring phytoplankton growth. It showed that re-sedimentation of released P and washout over the winter greatly mitigated its effect. Correlation analysis demonstrated that the very large summer releases of sediment P were not related directly to the spring inputs from diatom settlement. No long-term trends in P release were seen.

Community-living nonagenarians in northern ireland have lower plasma homocysteine but similar methylenetetrahydrofolate reductase thermolabile genotype prevalence compared to 70-89-year-old subjects.

This cross-sectional study assessed relationships between plasma homocysteine, 'thermolabile' methylenetetrahydrofolatereductase (MTHFR) genotype, B vitamin status and measures of renal function in elderly (70-89 years) and nonagenarian (90+ years) subjects, with the hypothesis that octo/nonagenarian subjects who remain healthy into old age as defined by 'Senieur' status might show reduced genetic or environmental risk factors usually associated with hyperhomocysteinaemia. Plasma homocysteine was 9.1 micromol/l (geometric mean [GM]) for all elderly subjects. Intriguingly, homocysteine was significantly lower in 90+ (GM; 8.2 micromol/l) compared to 70-89-year-old subjects (GM; 9.8 micromol/l) despite significantly lower glomerular filtration rate (GFR) and serum B12 in nonagenarian subjects and comparable MTHFR thermolabile (TT) genotype frequency, folate and B6 status to 70-89-year-olds. For all elderly subjects, the odds ratio and 95% confidence intervals for plasma homocysteine being in the highest versus lowest quartile was 4.27 (2.04-8.92) for age <90 compared >90 years, 3.4 (1.5-7.8) for serum folate <10.7 compared >10.7nmol/l, 3.0 (0.9-10.2) for creatinine >140 compared <140 umol/l and 2.1 (1.0-4.4) for male sex. This study shows that plasma homocysteine does not invariably increase with age. Compared to similarly enlisted 70-89-year-olds, apparently well, mentally alert, community-living 90+ year olds approximating 'Senieur' status, show lower homocysteine, which is unexplained by renal function, TT genotype and B vitamin status, suggesting that lower homocysteine may be associated with survival.

Evaluation of problem solving and communication skills of persons with schizophrenia.

Although much research has shown positive outcomes of teaching problem solving and communication skills to persons with schizophrenia, the amount of research on the assessment of these two sets of skills has been modest. The current study demonstrates an effective model for their assessment and includes a previously neglected procedure to determine if subjects attended to the skill prompts. It replicates and expands prior findings on problem solving and communication skills. Results indicated that persons with schizophrenia were generally deficit in problem solving skills. Persons without schizophrenia seemed to use more behavioral information when deciding if a problem existed and they were better able to differentiate between appropriate and inappropriate solutions to problems. Persons with schizophrenia were found to be deficit in communication skills that facilitate interaction and showed a style that subordinated their wants to those of others.

Helplessness, self-efficacy, cognitive distortions, and depression in multiple sclerosis and spinal cord injury.

The aim of this study was to determine if learned helplessness, self-efficacy, and cognitive distortions would predict depression in a sample of 80 individuals with multiple sclerosis (MS) and 80 individuals with a spinal cord injury (SCI). As MS and SCI usually present with disparate disease courses and etiologies, a secondary objective was to determine if individuals with MS would exhibit greater levels of helplessness, cognitive distortions, and depression and lower levels of self-efficacy than those with SCI. Results indicated that helplessness and self-efficacy significantly predicted depression for both the MS and SCI groups after controlling for confounding variables. Cognitive distortions had no independent effect, indicating that cognitive distortions may have caused feelings of helplessness and low self-efficacy and, in this way, had indirect effects on depression. The MS group exhibited significantly greater levels of depression and helplessness and significantly lower levels of self-efficacy than the SCI group. It was hypothesized that it may have been the combination of an unpredictable course of disease activity and the possibility of being affected by MS in many different ways that produced greater feelings of depression, helplessness, and low self-efficacy in the MS group.

Dissimilatory nitrate reduction in anaerobic sediments leading to river nitrite accumulation.

Recent studies on Northern Ireland rivers have shown that summer nitrite (NO(inf2)(sup-)) concentrations greatly exceed the European Union guideline of 3 (mu)g of N liter(sup-1) for rivers supporting salmonid fisheries. In fast-flowing aerobic small streams, NO(inf2)(sup-) is thought to originate from nitrification, due to the retardation of Nitrobacter strains by the presence of free ammonia. Multiple regression analyses of NO(inf2)(sup-) concentrations against water quality variables of the six major rivers of the Lough Neagh catchment in Northern Ireland, however, suggested that the high NO(inf2)(sup-) concentrations found in the summer under warm, slow-flow conditions may result from the reduction of NO(inf3)(sup-). This hypothesis was supported by field observations of weekly changes in N species. Here, reduction of NO(inf3)(sup-) was observed to occur simultaneously with elevation of NO(inf2)(sup-) levels and subsequently NH(inf4)(sup+) levels, indicating that dissimilatory NO(inf3)(sup-) reduction to NH(inf4)(sup+) (DNRA) performed by fermentative bacteria (e.g., Aeromonas and Vibrio spp.) is responsible for NO(inf2)(sup-) accumulation in these large rivers. Mechanistic studies in which (sup15)N-labelled NO(inf3)(sup-) in sediment extracts was used provided further support for this hypothesis. Maximal concentrations of NO(inf2)(sup-) accumulation (up to 1.4 mg of N liter(sup-1)) were found in sediments deeper than 6 cm associated with a high concentration of metabolizable carbon and anaerobic conditions. The (sup15)N enrichment of the NO(inf2)(sup-) was comparable to that of the NO(inf3)(sup-) pool, indicating that the NO(inf2)(sup-) was predominantly NO(inf3)(sup-) derived. There is evidence which suggests that the high NO(inf2)(sup-) concentrations observed arose from the inhibition of the DNRA NO(inf2)(sup-) reductase system by NO(inf3)(sup-).

Influence of orthostatic hypotension in Parkinson's disease on plasma atrial natriuretic peptide.

The effect of orthostatic hypotension in Parkinson's disease (PD) on plasma atrial natriuretic peptide (ANP) was examined in fifteen individuals with PD without autonomic dysfunction (63-85 years), nine PD patients with autonomic dysfunction (orthostatic hypotension; systolic BP change > 20 mmHg after 5 min standing: 69-82 years) and 14 fit elderly volunteers (62-93 years). The mean ANP level was 42.2 pg/ml (range 16.8-89.2 pg/ml) in the PD group without autonomic dysfunction; 44.4 pg/ml (range 27.2-91.2 pg/ml) in the PD group with autonomic dysfunction; and 48.5 pg/ml (range 22.2-111.6 pg/ml) in the elderly group. There was no statistical difference in plasma atrial natriuretic peptide between all three groups. The mean change in blood pressure was -39 mmHg (systolic) and -18 mmHg (diastolic) between supine and standing in the group with orthostatic hypotension.

Assessing patients with HIV-associated dementia.

HIV-associated dementia may pose communication challenges to healthcare staff. It is essential to obtain an accurate assessment of the confusion in order to achieve a baseline from which to evaluate a patient. It is important to communicate in a way that conveys worth and value to the patient. The expertise of the multidisciplinary team should be drawn on when working with such patients.

Plasma atrial natriuretic peptide levels in elderly hypertensives: effects of blood pressure reduction with amlodipine.

Atrial natriuretic peptide (ANP) is a hormone of relatively recent discovery concerned with sodium homeostasis. Increased levels of ANP are found in the elderly and in hypertensives, but the mechanisms for this are unclear. This study determined the effect of amlodipine, a calcium antagonist, which is the only class of antihypertensive agent that has little or no influence on the renin-angiotensin system (Bauer and Reams, 1988) on plasma ANP in a group of 18 elderly hypertensives and a placebo (vit B complex) on a further group of 6 elderly hypertensives. The mean pre-treatment plasma ANP was 62.7 pg/ml (range 18-148.7 pg/ml) and 52.0 pg/ml (range 15.0-148.4 pg/ml) after treatment with amlodipine (not statistically significant). However, systolic blood pressure fell from a mean of 181.6 mmHg to 151.1 mmHg and diastolic blood pressure fell from a mean of 101.6 mmHg to 83.6 mmHg after treatment with amlodipine (statistically significant, P < 0.001). In the group treated with vit B complex, the mean plasma ANP level was 68.4 pg/ml (range 31.4-119.5 pg/ml) before treatment and 63.6 pg/ml (range 29.2-127.3 pg/ml) after treatment. This was not statistically significant and there was no significant change in blood pressure. These findings reinforce the theory that raised plasma ANP levels found in elderly hypertensives are a function of the aging process itself or of age-related physiological changes rather than the result of hypertension.

Plasma atrial natriuretic polypeptide in the elderly: age or hypertension?

The effect of age and raised blood pressure on the plasma concentration of atrial natriuretic peptide (ANP) was examined in 20 young (23-49 years), 20 elderly normotensive (71-80 years) and 20 elderly hypertensive (71-82 years, BP > 160/90 mmHg) individuals. Median plasma ANP was 27.6 pg/ml (range, 16.8-94.0 pg/ml) in the young group; 62.0 pg/ml (range, 28.6-124.3 pg/ml) in the elderly normotensive and 74.4 pg/ml (range,25.2-423.6 pg/ml) in the elderly hypertensive group. Plasma ANP rose significantly with age, but there was no difference between elderly normotensive and hypertensive groups.

Aorto-cutaneous fistula: a rare complication of aortic surgery.

Two cases of false aneurysm of the ascending aorta which presented with discharge of arterial blood from a sternal wound are discussed. The first presented 8 years after aortic valve surgery and was diagnosed by contrast enhanced computerised tomography of the thorax. The second presented 6 months following repair of an aortic dissection and the diagnosis was confirmed by thoracic magnetic resonance imaging. The diagnosis and surgical management of these cases are reviewed.

Function of cigarette smoking in relation to examinations.

Eighty-two college students took part in a study on motives underlying increases in cigarette smoking prior to examinations. One group was tested a month before, and a second group was tested the day before, the start of examinations. Measures were taken of current cigarette consumption, general anxiety, anxiety about forthcoming exams, the importance of sedative and stimulant smoking motives, hours spent revising and in other activities and amounts smoked during these activities. The results indicated that the students increased the hours they spent revising and there was a corresponding increase in the number of cigarettes smoked during this activity. They also reported an increase in the importance of stimulant smoking motives. Anxiety levels increased in the run up to exams but there was no increase in sedative smoking motives. The results raise the issue of whether any anxiolytic action of nicotine may be limited to acute stressors and also whether smokers' use of cigarettes to help them stay alert during revision translates into improved examination performance.

Entrapping of the clotted intra-aortic balloon in the descending aorta.

Percutaneous insertion of a catheter for intra-aortic balloon pumping (IABP) was introduced in 1979 by Bregman and Casarella and has become a popular technique. Rupture of the balloon, allowing clot to form inside it, is rare. When the clot is large, it may cause entrapping of the balloon. This is a potentially dangerous complication of IABP. We are aware of only one case report of this complication, by Aru and co-workers. The entrapping of the balloon in their report occurred at the site of insertion in the femoral artery. We report here a case in which the entrapping occurred in the descending aorta, and its removal required extensive exposure of the aortic bifurcation.

The effect of propranolol on the cerebral electrical response to deep hypothermia and total circulatory arrest in lambs.

Deep hypothermia with total circulatory arrest is an important technique in the surgical treatment of complex congenital heart defects. The effects of propranolol on cerebral electrical activity in lambs undergoing a 90-minute period of circulatory arrest after initial surface cooling to 26 degrees C and subsequent core cooling to 15 degrees C was studied by means of the cerebral function analyzing monitor. Five of the lambs were pretreated with intravenous propranolol 0.2 mg/kg (group I) and five acted as controls (group II). The surface cooling phase was associated with a continuous decrease in mean electroencephalographic voltage +/- standard error, which decreased from 82.8 +/- 11.8 microV at 37 degrees C to 31.6 +/- 2.4 microV at 26 degrees C in the control group compared with 75.0 +/- 7.4 microV and 63.2 +/- 9.2, respectively, in the propranolol group (p less than 0.05). During the rewarming phase, the latency to (1) initial appearance of electrical activity, (2) continuous recording with the cerebral function analyzing monitor, and (3) maximum voltage and frequency recovery was 2.0 +/- 1, 5.9 +/- 4, and 32.4 +/- 8 minutes in the propranolol group, which was significantly (p less than or equal to 0.01) shorter than in the control group (18.4 +/- 3, 38.2 +/- 5, and 111.0 +/- 9 minutes, respectively). These results suggest that pretreatment with propranolol may play an important part in the brain tolerance to deep hypothermia and circulatory arrest.