Past and future global transformation of terrestrial ecosystems under climate change.

Impacts of global climate change on terrestrial ecosystems are imperfectly constrained by ecosystem models and direct observations. Pervasive ecosystem transformations occurred in response to warming and associated climatic changes during the last glacial-to-interglacial transition, which was comparable in magnitude to warming projected for the next century under high-emission scenarios. We reviewed 594 published paleoecological records to examine compositional and structural changes in terrestrial vegetation since the last glacial period and to project the magnitudes of ecosystem transformations under alternative future emission scenarios. Our results indicate that terrestrial ecosystems are highly sensitive to temperature change and suggest that, without major reductions in greenhouse gas emissions to the atmosphere, terrestrial ecosystems worldwide are at risk of major transformation, with accompanying disruption of ecosystem services and impacts on biodiversity.

Rapid global ocean-atmosphere response to Southern Ocean freshening during the last glacial.

Contrasting Greenland and Antarctic temperatures during the last glacial period (115,000 to 11,650 years ago) are thought to have been driven by imbalances in the rates of formation of North Atlantic and Antarctic Deep Water (the 'bipolar seesaw'). Here we exploit a bidecadally resolved 14C data set obtained from New Zealand kauri (Agathis australis) to undertake high-precision alignment of key climate data sets spanning iceberg-rafted debris event Heinrich 3 and Greenland Interstadial (GI) 5.1 in the North Atlantic (~30,400 to 28,400 years ago). We observe no divergence between the kauri and Atlantic marine sediment 14C data sets, implying limited changes in deep water formation. However, a Southern Ocean (Atlantic-sector) iceberg rafted debris event appears to have occurred synchronously with GI-5.1 warming and decreased precipitation over the western equatorial Pacific and Atlantic. An ensemble of transient meltwater simulations shows that Antarctic-sourced salinity anomalies can generate climate changes that are propagated globally via an atmospheric Rossby wave train.A challenge for testing mechanisms of past climate change is the precise correlation of palaeoclimate records. Here, through climate modelling and the alignment of terrestrial, ice and marine 14C and 10Be records, the authors show that Southern Ocean freshwater hosing can trigger global change.

Humans rather than climate the primary cause of Pleistocene megafaunal extinction in Australia.

Environmental histories that span the last full glacial cycle and are representative of regional change in Australia are scarce, hampering assessment of environmental change preceding and concurrent with human dispersal on the continent ca. 47,000 years ago. Here we present a continuous 150,000-year record offshore south-western Australia and identify the timing of two critical late Pleistocene events: wide-scale ecosystem change and regional megafaunal population collapse. We establish that substantial changes in vegetation and fire regime occurred ∼70,000 years ago under a climate much drier than today. We record high levels of the dung fungus Sporormiella, a proxy for herbivore biomass, from 150,000 to 45,000 years ago, then a marked decline indicating megafaunal population collapse, from 45,000 to 43,100 years ago, placing the extinctions within 4,000 years of human dispersal across Australia. These findings rule out climate change, and implicate humans, as the primary extinction cause.

The aftermath of megafaunal extinction: ecosystem transformation in Pleistocene Australia.

Giant vertebrates dominated many Pleistocene ecosystems. Many were herbivores, and their sudden extinction in prehistory could have had large ecological impacts. We used a high-resolution 130,000-year environmental record to help resolve the cause and reconstruct the ecological consequences of extinction of Australia's megafauna. Our results suggest that human arrival rather than climate caused megafaunal extinction, which then triggered replacement of mixed rainforest by sclerophyll vegetation through a combination of direct effects on vegetation of relaxed herbivore pressure and increased fire in the landscape. This ecosystem shift was as large as any effect of climate change over the last glacial cycle, and indicates the magnitude of changes that may have followed megafaunal extinction elsewhere in the world.

Development of a structured clinical operative test (SCOT) in the assessment of practical ability in the oral surgery undergraduate curriculum.

Competence in undergraduate oral surgery involves assessment of the students' knowledge, practical skill and attitude. The assessment of practical skills can be achieved using a formative assessment method such as the structured clinical operative test (SCOT) which uses a checklist for the assessment of a clinical task. The aim of this study was primarily to determine whether SCOTs could be integrated into the oral surgery undergraduate course, and secondarily to collect feedback from both the students and the staff on this assessment. A validated checklist was used by trained examiners to assess the performance of 49 students in their second clinical year undertaking simple exodontia. Feedback was collected from the students by questionnaire and from the staff by interview. The SCOT was well received by both students and staff. The main problem highlighted by the students was the perceived inter-examiner variability and by the staff, the disruptive effect on the clinics. The checklist must be objective enough to prevent misinterpretation. Despite these limitations, the SCOT provides a more objective assessment and serves to highlight weaker students, allowing them to be targeted for closer supervision and instruction as well as providing the students with a tool to measure their progress in oral surgery. The use of peer assessment by students may alleviate the burden on the staff.

Millennial and orbital variations of El Niño/Southern Oscillation and high-latitude climate in the last glacial period.

The El Niño/Southern Oscillation (ENSO) phenomenon is believed to have operated continuously over the last glacial-interglacial cycle. ENSO variability has been suggested to be linked to millennial-scale oscillations in North Atlantic climate during that time, but the proposals disagree on whether increased frequency of El Niño events, the warm phase of ENSO, was linked to North Atlantic warm or cold periods. Here we present a high-resolution record of surface moisture, based on the degree of peat humification and the ratio of sedges to grass, from northern Queensland, Australia, covering the past 45,000 yr. We observe millennial-scale dry periods, indicating periods of frequent El Niño events (summer precipitation declines in El Niño years in northeastern Australia). We find that these dry periods are correlated to the Dansgaard-Oeschger events--millennial-scale warm events in the North Atlantic climate record--although no direct atmospheric connection from the North Atlantic to our site can be invoked. Additionally, we find climatic cycles at a semiprecessional timescale (approximately 11,900 yr). We suggest that climate variations in the tropical Pacific Ocean on millennial as well as orbital timescales, which determined precipitation in northeastern Australia, also exerted an influence on North Atlantic climate through atmospheric and oceanic teleconnections.

Assessing long-term pH change in an Australian river catchment using monitoring and palaeolimnological data.

Reviews of stream monitoring data suggest that there has been significant acidification (>1.0 pH unit at some sites) of Victorian streamwaters over the past 3 decades. To assess whether these declines are within the range of natural variability, we developed a diatom model for inferring past pH and applied it to a ca. 3500-yr diatom record from a flood plain lake, Callemondah 1 Billabong, on the Goulburn River, which has among the most substantial observed pH declines. The model has a jackkniffed r2 between diatom inferred and measured pH of 0.77 and a root mean square error of prediction of 0.35 pH units. In the pre-European period, pH was stable (range 6.5-6.7) for approximately 3000 yr. Since European settlement around 160 yr ago, diatom-inferred billabong pH has increased significantly by >0.5 units. We hypothesize that this increase in pH is related to processes associated with land clearance (e.g., increased base cation load and decreased organic acid load). There is no evidence of the recent monitored declines in the Callemondah record, which may indicate that that flood plain lakes and the main stream are experiencing divergent pH trends or that the temporal resolution in the billabong sediment record is insufficient to register recent declines.

Psychiatric symptoms and CAG repeats in neurologically asymptomatic Huntington's disease gene carriers.

The putative relationship between the psychiatric profile of a sample of neurologically asymptomatic Huntington's disease gene carriers and CAG repeats was investigated. The psychiatric assessments (by consultant psychiatrist and computerised battery) were undertaken before the genetic testing was carried out. In this way, the informational distortions caused by neurological and cognitive deficits were avoided. The hypothesis that there is a relationship between psychiatric and CAG repeats was tested by seeking direct correlations between psychiatric systems and CAG repeats, and also by correcting the correlation by the number of years above or below the estimated age of onset in Huntington's disease. Scores for irritability and cognitive failures were high in the sample. There was no correlation between any psychiatric variable and CAG repeats. Possible explanations for this lack of correlations are discussed.

Use of theatre time for dentoalveolar operations under general anaesthesia.

Efficient use of hospital resources is essential if waiting lists are to be reduced. We undertook this study because there seems to be little information on the use of theatre time for dentoalveolar surgery under general anaesthesia. The time taken for each sequence of events (from start of case, induction, operation to recovery, and so on) for each patient was recorded. Of the 30 lists examined, 22 lists (73%) finished on time or early, and 8 lists (27%) ran late. The time spent operating occupied less than 50% of theatre time available. The 'total time' for each case was increased (by about 10 minutes a patient) when a junior anaesthetist was anaesthetizing rather than a consultant. The overall time used per list was 79% with the remaining 21% of the list being 'unused'. Where these lists did over-run, then this was usually because the operation took longer, although grade of anaesthetist was a factor. We identified several areas in which efficiency could be improved.

Registration of Forensic Medical Practitioners. The expression of a standard.

The Council for the Registration of Forensic Practitioners (CRFP) has been set up, in the wake of high profile miscarriages of justice, to promote confidence in forensic practice in the UK. Its Governing Council consists of users, practitioners and lay members. It will publish a register of competent practitioners; set standards for them; and deal with practitioners whose fitness to practise is questioned. Registration will be based on an assessment of competence by peer review. Revalidation will follow every 4 years (the General Medical Council's new proposals involve a 5-year revalidation). There are significant advantages in these proposals for forensic medical practitioners over and above existing regulatory arrangements.

Evidence for specific cognitive deficits in preclinical Huntington's disease.

The performance of 54 subjects genetically at risk for Huntington's disease was examined in double-blind fashion on a series of computerized tests from the Cambridge Neuropsychological Test Automated Battery. None of the subjects exhibited clinical movement disorder characteristic of Huntington's disease. Of the 54 subjects, 22 were Huntington's disease mutation carriers and 32 were non-carriers. On a comprehensive battery of neuropsychological tests previously shown to be sensitive to the early stages of clinical Huntington's disease, Huntington's disease mutation carriers exhibited highly specific cognitive deficits. In particular, Huntington's disease mutation carriers performed significantly less well than non-carriers, matched for age and IQ, on tests of attentional set shifting and semantic verbal fluency. Furthermore, performance on these two tests was significantly correlated, even after partialling out the effects of age and IQ. It is suggested that these cognitive impairments relate to a common deficit in inhibitory control mechanisms, under the control of striatofrontal mechanisms, and that such a deficit is present in Huntington's disease mutation carriers prior to the onset of definite motor symptomatology. The implications for the nature of the cognitive decline seen in Huntington's disease, and possible future treatment strategies, are discussed.

Recommendations for education and training of genetic nurses and counsellors in the United Kingdom.

Genetic nurses and counsellors work as part of the professional team providing clinical genetic services from regional centres in the United Kingdom. The education and training needs of genetic nurses and counsellors have not previously been formally identified. The guidelines presented have been devised to equip practitioners to fulfil their professional role as defined in a previous study, by identifying objectives, educational pathways, and means of assessment. While academic courses provide an essential framework, experiential learning in a clinical setting is also considered a vital component of the preparation for practice.

The management of drooling in children and patients with mental and physical disabilities: a literature review.

Amongst the duties of the paediatric dentist is the provision of oral care to patients with the problem of drooling. Many, but certainly not all, of these patients have physical and/or learning disabilities. Various methods have been advocated for the management of drooling in the paediatric patient and older patients with disabilities, including behavioural programmes, biofeedback techniques, physiotherapy, biofunctional oral appliances, medication and surgery. It is of paramount importance that the patients and/or carers understand the advantages and disadvantages of any treatment method being considered. The paediatric dentist has an important role to play in explaining the different options to the patients and carers, and in implementing some treatment modalities, particularly non-surgical approaches. Referral to surgical specialists should be seen as 'a last resort' and suggested only if other treatment methods have been exhausted. If pharmacological or surgical treatment is carried out, careful monitoring for the development of dental caries and other problems is essential. The aim of this paper is to provide the paediatric dentist with concise overall knowledge of the causes of drooling and treatment options available.

Second-trimester maternal serum screening using alpha-fetoprotein, human chorionic gonadotrophin, and unconjugated oestriol: experience of a regional programme.

Over a 2-year period from January 1991 to December 1992, second-trimester maternal serum screening for Down's syndrome using alpha-fetoprotein (alpha FP), human chorionic gonadotrophin (hCG), and unconjugated oestriol (uE3) was made available to five health districts in East Anglia, with a total population of 1.2 million. Amniocentesis was offered when the risk of Down's syndrome at term was 1:200 or greater. 25,359 singleton pregnancies were screened, representing an uptake of 77 per cent. The recall rate for the 24 per cent of women who had not had a dating scan prior to the test was 9.4 per cent compared with 3.9 per cent for those who had been scanned (P < 0.0005). Seventy-five per cent (36/48) of Down's syndrome pregnancies were detected for a false-positive rate of 4.0 per cent. Twenty-five out of 36 of detected Down's syndrome pregnancies were dated by scan prior to sampling, and in the 11 remaining cases, the dates were confirmed by scan after a high-risk result was obtained. The exclusion of uE3 from the screening protocol would have reduced the detection rate to 52 per cent (25/48) for the same false-positive rate. Eighty-five per cent of women identified at high risk accepted the offer of an amniocentesis. Other fetal abnormalities detected were trisomy 18 (3), trisomy 13 (2), 45,X (6), 69,XXX (5), other chromosome abnormalities (9), open neural tube defects (26), hydrocephalus (7), abdominal wall defects (4), and steroid sulphatase deficiency (6).

Changes in social support and quality of life: a case study of a man with an enduring psychotic illness.

The Government's White Paper on community care has drawn attention to the importance of assessing changes in a person's well-being which occur as a consequence of clinical and social interventions. In the UK the evaluation of the quality of life of people with chronic mental illness is relatively new. This case study demonstrates the use of the 'Lancashire Quality of Life Profile' in routine clinical practice with reference to residential changes in the 'care programme' of a person with a long history of a severely disabling psychotic illness. The formulation and review of his care plan were determined by a network of agencies involved in his long term care.

Determination of intracellular free magnesium by nuclear magnetic resonance in human magnesium deficiency.

Magnesium (Mg) deficiency is a common clinical problem. As Mg is predominantly an intracellular cation and Mg deficiency may exist despite normal serum Mg (sMg) concentrations, we have utilized nuclear magnetic resonance (NMR) techniques in an attempt to measure intracellular free Mg (Mg2+) in red blood cells (RBC). Twenty normal subjects, 22 hypomagnesemic patients, and 17 normomagnesemic alcoholic patients were studied. Mean RBC Mg2+ in normal subjects (178 +/- 6.3 microM) was significantly greater than in hypomagnesemic patients (146 +/- 7.1 microM, p less than 0.002). RBC Mg2+ correlated with sMg concentration (r = 0.54, p less than 0.001). In addition, four normal subjects were given a low Mg diet for 3 weeks. There was a progressive fall in both the sMg concentration and RBC Mg2+ during Mg depletion, with a concomitant rise in retention of a parenterally administered Mg load. These data suggest that the determination of intracellular Mg2+ by NMR may be a useful research tool in assessing the effect of changes in Mg2+ on intracellular processes. Its utility in the clinical evaluation of disorders of Mg deficiency remains to be determined.

Disposition of metronidazole and its effects on sulphasalazine metabolism in patients with inflammatory bowel disease.

The pharmacokinetics of metronidazole were studied after oral and intravenous administration to seven patients with Crohn's disease and five patients with ulcerative colitis. The oral/intravenous availability ratio was 0.97 +/- 0.2 in the Crohn's patients and 0.90 +/- 0.1 in the colitics (mean +/- s.e. mean). Plasma clearance was 3.24 +/- 0.2 l h-1 and 4.1 +/- 0.5 l h-1, respectively. These differences were not statistically significant. Ten of the patients on long term sulphasalazine were studied to observe the effect of 2 weeks metronidazole therapy on plasma sulphapyridine concentration. The sulphapyridine concentration changed from 22.1 +/- 2.0 micrograms ml-1 to 15.95 +/- 4.5 micrograms ml-1 in the Crohn's patients and 26.0 +/- 6.0 micrograms ml-1 to 36.4 +/- 8.5 micrograms ml-1 in the colitis group, pre- and post-metronidazole. These differences were not statistically significant. These results suggest that metronidazole does not interfere with diazo-link splitting of sulphasalazine and that patients with Crohn's disease handle metronidazole in a similar manner to patients with colitis.