Impaired trunk stability in individuals at high risk for Parkinson's disease

Background

The search for disease-modifying treatments for Parkinson''s disease advances, however necessary markers for early detection of the disease are still lacking. There is compelling evidence that changes of postural stability occur at very early clinical stages of Parkinson''s disease, making it tempting to speculate that changes in sway performance may even occur at a prodromal stage, and may have the potential to serve as a prodromal marker for the disease.

Methodology/Principal Findings

Balance performance was tested in 20 individuals with an increased risk of Parkinson''s disease, 12 Parkinson''s disease patients and 14 controls using a cross-sectional approach. All individuals were 50 years or older. Investigated groups were similar with respect to age, gender, and height. An accelerometer at the centre of mass at the lower spine quantified sway during quiet semitandem stance with eyes open and closed, as well as with and without foam. With increasing task difficulty, individuals with an increased risk of Parkinson''s disease showed an increased variability of trunk acceleration and a decrease of smoothness of sway, compared to both other groups. These differences reached significance in the most challenging condition, i.e. the eyes closed with foam condition.

Conclusions/Significance

Individuals with an increased risk of Parkinson''s disease have subtle signs of a balance deficit under most challenging conditions. This preliminary finding should motivate further studies on sway performance in individuals with an increased risk of Parkinson''s disease, to evaluate the potential of this symptom to serve as a biological marker for prodromal Parkinson''s disease.     

McMaster's pioneer in evidence-based medicine now spreading his message in England.

Dr. David Sackett, formerly of McMaster University and now at Oxford University in England, is considered one of the pioneers of the evidence-based medicine movement. This article looks at his colleagues'' assessment of Sackett''s contributions to medicine and at Sackett''s own views on his lengthy career.     

Blood gas analysis: effect of air bubbles in syringe and delay in estimation.

Two common sources of error in blood pH and blood gas analysis were studied. The effect of delay in estimation was studied in 10 volunteers and 40 patients. Syringes were stored at 0 degree C, (crushed ice), 4 degrees C (refrigerator) and 22 degrees C (room temperature). The pressure of oxygen (PO2) fell significantly by 20 minutes at 4 degrees C and 22 degrees C but did not change significantly at 0 degree C for up to 30 minutes. Blood pH, pressure of carbon dioxide (PCO2), and base excess did not change significantly for up to 30 minutes at 4 degrees C and 22 degrees C and up to 60 minutes at 0 degrees C. The effect of air bubbles in the syringe was studied by leaving a single bubble or froth in contact with the blood for one to five minutes in 40 patients. Po2 rose significantly after two minutes'' contact with froth and two minutes'' contact with the air bubble, and PCO2 fell significantly after three minutes'' contact with the air bubble. Size of the bubble had little effect on rates of change. Blood pH, bicarbonate, TCO2, and base excess did not change significantly after up to five minutes'' contact. For accurate estimation of PO2 and PCO2 it is necessary to avoid frothing, to expel all air bubbles within two minutes, and to inject the sample into the machine within 10 minutes or store the syringe in crushed ice. The requirements for blood pH and base excess measurement are less exacting.     

Surgical audit: Comparison of the work load and results of two hospitals in the same district.

Surgical audit is being undertaken to monitor and compare (by computer) the type of patient, work load, and results of two similar surgical units. Both units are in the City and Hackney District of London, one at St Bartholomew''s Hospital and the other at Hackney Hospital. During 1978, 736 patients were admitted by the unit at St Bartholomew''s Hospital and 902 by the unit at Hackney. At St Bartholomew''s 70% of admissions were elective compared with 49% at Hackney, where 86% of patients lived within the district compared with only 36% at St Bartholomew''s. The wound was the commonest site for complications, infection affecting 9% of those at Hackney and 6% at St Bartholomew''s, despite identical antibiotic policies. There were six post-operative deaths at St Bartholomew''s and 32 at Hackney. In both hospitals the length of stay was similar, 50% of patients being discharged within one week and 80% within two weeks. As a result of the audit a vigorous venous thrombosis prophylactic regimen has been instituted, and at Hackney the anaesthetic department has been strengthened and a new intensive care unit opened.     

Traumatic vasospastic disease in chain-saw operators.

Raynaud''s phenomenon is commonly induced in chain-saw operators by vibration; the hand guiding the tool is the more severely affected. The condition tends to persist after use of the chain-saw is stopped but compensation is rarely sought. Among 17 cases of Raynaud''s phenomenon in lumberjacks the condition was found to be related to use of the chain-saw in 14, 10 of whom had to give up their work in colder weather because the disease was so disabling. Two criteria essential to establish the condition as vibration-induced Raynaud''s phenomenon are the presence of symptoms for at least 2 years and a history of at least 1 year''s constant use of the chain-saw. Careful physical examination and simple tests of vascular function will provide objective evidence of permanent damage by which the patients may be classified and compensated.     

Gloger's rule in plants: The species and ecosystem levels

Gloger''s rule posits that darker birds are found more often in humid environments than in arid ones, especially in the tropics. Accordingly, desert-inhabiting animals tend to be light-colored. This rule is also true for certain mammalian groups, including humans. Gloger''s rule is manifested at 2 levels: (1) at the species level (different populations of the same species have different pigmentation at different latitudes), and (2) at the species assembly level (different taxa at a certain geography have different pigmentation than other taxa found at different habitats or latitudes). Concerning plants, Gloger''s rule was first proposed to operate in many plant species growing in sand dunes, sandy shores and in deserts, because of being white, whitish, or silver colored, based on white trichomes, because of sand grains and clay particles glued to sticky glandular trichomes, or because of light-colored waxes. Recently, Gloger''s rule was shown to also be true at the intraspecific level in relation to protection of anthers from UV irradiation. While Gloger''s rule is true in certain plant taxa and ecologies, there are others where “anti-Gloger” coloration patterns exist. In some of these the selective agents are known and in others they are not. I present both Gloger and “anti-Gloger” cases and argue that this largely neglected aspect of plant biology deserves much more research attention.     

AIDS in children

The application of medical quality assurance principles to ambulatory patient care using the traditional methods of medical chart audit, process review, and physician education has yielded generally disappointing results in improving patient care and physician performance. Newer methods assist physicians by providing patient and medical reference data at the time of a patient''s visit. Techniques for tracking treatment outcomes and patients'' test results and for providing instructions to patients may improve both care and patients'' and physicians'' satisfaction.This feature appears regularly in THE WESTERN JOURNAL OF MEDICINE. It is intended to cover recent developments in a broad range of issues that will have an impact—either directly or indirectly—on clinical practice. Occasionally the seminars may include informed speculation about likely future developments.     

Effect of a training programme to reduce stress in carers of patients with dementia.

OBJECTIVE--To reduce the psychological stress and improve the skills in coping of people who care for relatives with dementia. DESIGN--Assessment and suitability of carers by questionnaire; assessment of patients and carers in a hospital outpatient clinic; allocation to groups according to date of application to study. Linkage of groups of four carers and programme coordinator by telephone conference calls over 12 months after programmes. Reassessment at three, six, 12, and, for those in the "wait list" group, 18 months. SETTING--The programmes were conducted in the psychiatry unit of a Sydney teaching hospital. SUBJECTS--Eligible patients were less than 80 years old, had mild to moderate dementia, and lived at home with their carer. Of the 96 patient-carer pairs in the study, 33 were in the dementia carers'' programme group, 31 were in the memory retraining group, and 32 were in the wait list group. INTERVENTIONS--Carers in the dementia carers'' programme received training in coping with the difficulties of looking after patients with dementia while the patients had sessions in subjects such as memory retraining. In the memory retraining programme patients were admitted and received the patient component of the carers'' programme while their carers had 10 days'' respite. In the wait list group carers waited six months before undertaking the carers'' programme. MAIN OUTCOME MEASURES--Effect of the programmes on carers'' general health questionnaire scores and the rate of placement of patients in institutions. RESULTS--At 12 months'' follow up the carers'' programme had resulted in significantly lower psychological stress among carers than the memory retraining programme (mean (SD) general health questionnaire scores at 0 months were 6.31 (6.23) and 3.60 (6.25) respectively, and at 12 months were 4.69 (5.58) and 7.40 (9.39); p less than 0.05.) In the wait list group distress scores remained stable, even after the carers and patients had undertaken the carers'' programme. Patients deteriorated over 12 months regardless of group allocation, but at 30 months, allowing for patients who died and could not be included in the analysis, 65% of patients in the carers'' programme group were still living at home compared with 26% in the memory retraining programme group. CONCLUSION--The intensive intervention programme described for carers of patients with dementia can reduce the psychological morbidity of the carer and delay the placement of the patient in an institution without increasing the use of health services by either patient or carer.     

Results of case-control study of leukaemia and lymphoma among young people near Sellafield nuclear plant in West Cumbria.

OBJECTIVE--To examine whether the observed excess of childhood leukaemia and lymphoma near the Sellafield nuclear plant is associated with established risk factors or with factors related to the plant. DESIGN--A case-control study. SETTING--West Cumbria health district. SUBJECTS--52 Cases of leukaemia, 22 of non-Hodgkin''s lymphoma, and 23 of Hodgkin''s disease occurring in people born in the area and diagnosed there in 1950-85 under the age of 25 and 1001 controls matched for sex and date of birth taken from the same birth registers as the cases. MAIN OUTCOME MEASURES--Antenatal abdominal x ray examinations, viral infections, habit factors, proximity to and employment characteristics of parents at Sellafield. RESULTS--Expected associations with prenatal exposure to x rays were found, but little information was available on viral illnesses. Relative risks for leukaemia and non-Hodgkin''s lymphoma were higher in children born near Sellafield and in children of fathers employed at the plant, particularly those with high radiation dose recordings before their child''s conception. For example, the relative risks compared with area controls were 0.17 (95% confidence interval 0.05 to 0.53) for being born further than 5 km from Sellafield 2.44 (1.04 to 5.71) for children of fathers employed at Sellafield at their conception, and 6.42 (1.57 to 26.3) for children of fathers receiving a total preconceptual ionising radiation dose of 100 mSv or more. Other factors, including exposure to x rays, maternal age, employment elsewhere, eating seafood, and playing on the beach did not explain these relationships. Focusing on Seascale, where the excess incidence has predominantly been reported, showed for the four out of five cases of leukaemia and one case of non-Hodgkin''s lymphoma whose fathers were employed at Sellafield and for whom dose information was obtained that the fathers of each case had higher radiation doses before their child''s conception than all their matched control fathers; the father of the other Seascale case (non-Hodgkin''s lymphoma) was not employed at the plant. These results seem to explain statistically the geographical association. For Hodgkin''s disease neither geographical nor employment associations with Sellafield were found. CONCLUSIONS--The raised incidence of leukaemia, particularly, and non-Hodgkin''s lymphoma among children near Sellafield was associated with paternal employment and recorded external dose of whole body penetrating radiation during work at the plant before conception. The association can explain statistically the observed geographical excess. This result suggests an effect of ionising radiation on fathers that may be leukaemogenic in their offspring, though other, less likely, explanations are possible. There are important potential implications for radiobiology and for protection of radiation workers and their children.     

Light microscope autoradiography of ribosomal DNA amplification in Xenopus laevis

A technique for the isolation of very high molecular weight rDNA¹ from the ovary of Xenopus laevis is described. Tritiated rDNA was prepared by this method from ovaries at the amplification stage, and spread on slides for light microscope autoradiography. The average molecular weight of the spread DNA was greater than 180×10⁶ daltons. Unlike chromosomal DNA grain tracks, rDNA tracks after 2 or 4 hours of labelling were not tandemly arranged. By allowing ovaries to equilibrate gradually with exogenous precursors, tracks showing a single gradient of grain density were produced, indicating that replication was proceeding in one direction at these sites. Bidirectional initiations, if they occur at all during amplification, are rare. The rate of rDNA chain growth is 10.5 μ/hour at 23° C, which is the same as the rate for chromosomal DNA synthesis in X. laevis. After 24 hours some tracks are over 200 μ long, suggesting that replication at a site may be continuous for at least this period. Although they do not distinguish between several alternative mechanisms, the results are compatible with a rolling circle mechanism for gene amplification.     

Penetration and Development of Meloidogyne hapla in Resistant and Susceptible Alfalfa Under Differing Temperatures

Studies were conducted to examine under differing temperatures (12, 16, 20, 24, 28, and 32 C) the penetration anti development of Meloidogyne hapla in resistant lines ''298'' and ''Nev. Syn XX'', and susceptible ''Lahontan'' and ''Ranger'' hardy-type alfalfas. The results indicated that resistance to M. hapla was similar to that previously described for M. incognita in nonhardy alfalfa. Although initial penetration in resistant seedlings was similar to that of susceptible seedlings, nematode larvae failed to establish and develop in root tissues and nematode numbers subsequently declined. In susceptible seedlings, nematode development proceeded rapidly, and egg production began after 5 weeks. Temperature had little influence on the nematode development except to slow the response at the lower temperatures. Other studies were conducted to verify a previously reported immune (no penetration) reaction to M. hapla by the ''Vernal'' selection ''M-4''. When compared to the resistant (penetration without nematode development) Vernal selection ''M-9'' under differing temperatures (20, 24, 28, and 32 C), each selection was equally penetrated by M. hapla but at a lower level than in susceptible Ranger cuttings. Generally, no root galling was observed in either M-4 or M-9; however, very slight galling was found 35 days after inoculation on about 50% of these cuttings when grown at 32 C.     

Epidemiology of Alzheimer's presenile dementia in Scotland, 1974-88.

OBJECTIVE--To describe the epidemiology of presenile Alzheimer''s disease in Scotland from 1974 to 1988. DESIGN--Retrospective review of hospital records of patients aged less than 73 years admitted to psychiatric hospital with various diagnoses of dementia. Diagnoses were classified by National Institute for Communicative Disorders and Stroke and Alzheimer''s Disease and Related Disorders Association Criteria and the Hachinski score. Completeness of the study sample was evaluated by scrutiny of neurology outpatient and general hospital records. SETTING--All general psychiatric hospitals in Scotland. SUBJECTS--All patients with onset of dementia aged 40-64. MAIN OUTCOME MEASURES--Probable and broad Alzheimer''s disease, sex of patient, age at onset. RESULTS--5874 psychiatric hospital records, 129 neurology outpatient records, and 89 records from non-psychiatric hospitals were examined. 317 patients met criteria for probable Alzheimer''s disease, 569 met criteria for broad Alzheimer''s disease, and 267 met those for multi-infarct dementia. Minimal incidences per 100,000 population aged 40-64 years were 22.6 (95% confidence interval, 20.2 to 25.2) and 40.5 (38.9 to 42.3) per 100,000 for probable and broad Alzheimer''s disease. In the 1981 census year the annual incidence of probable Alzheimer''s disease was 1.6 (1.0 to 2.6). Women were at greater risk with incidence rates for probable Alzheimer''s disease of 28.2 (24.5 to 32.4) per 100,000 compared with 16.5 (13.8 to 19.8) per 100,000 for men. The incidence per 100,000 for multi-infarct dementia was greater in men (25.1, 23.3 to 27.1) than women (13.4, 12.1 to 14.8). CONCLUSION--Female sex seems to be positively associated with development of Alzheimer''s disease before age 65 years.     

Immune response in human subjects at high altitude

Levels of immunoglobulins were determined in persons exposed to high altitude. The individuals studied included high altitude natives, sea level residents at high altitude for 2 years, and recent arrivals at high altitude. Increased IgG and IgA levels were found in high altitude natives and sea level residents at high altitude for 2 years when compared with sea level residents. In recent arrivals marked increase of IgG and IgG levels and slight rise in IgM was seen. Recent arrivals who suffered from high altitude pulmonary oedema showed marked elevation of IgG, IgM, and IgA. Immunoglobulin responses to both primary and secondary TAB inoculation were of a higher magnitude and more sustained at high altitude than at sea level.     

Evolution of scaling emergence in large-scale spatial epidemic spreading

Background

Zipf''s law and Heaps'' law are two representatives of the scaling concepts, which play a significant role in the study of complexity science. The coexistence of the Zipf''s law and the Heaps'' law motivates different understandings on the dependence between these two scalings, which has still hardly been clarified.

Methodology/Principal Findings

In this article, we observe an evolution process of the scalings: the Zipf''s law and the Heaps'' law are naturally shaped to coexist at the initial time, while the crossover comes with the emergence of their inconsistency at the larger time before reaching a stable state, where the Heaps'' law still exists with the disappearance of strict Zipf''s law. Such findings are illustrated with a scenario of large-scale spatial epidemic spreading, and the empirical results of pandemic disease support a universal analysis of the relation between the two laws regardless of the biological details of disease. Employing the United States domestic air transportation and demographic data to construct a metapopulation model for simulating the pandemic spread at the U.S. country level, we uncover that the broad heterogeneity of the infrastructure plays a key role in the evolution of scaling emergence.

Conclusions/Significance

The analyses of large-scale spatial epidemic spreading help understand the temporal evolution of scalings, indicating the coexistence of the Zipf''s law and the Heaps'' law depends on the collective dynamics of epidemic processes, and the heterogeneity of epidemic spread indicates the significance of performing targeted containment strategies at the early time of a pandemic disease.     

Aflatoxin in human and camel milk in Abu Dhabi,United Arab Emirates

During an initial survey, using thin layer chromatography, 10 of 64 samples of mothers’ breast milk, collected from donors at the Corniche Maternity Hospital and the Al-Nehyan Clinic for Maternity and Childhood, were found to contain Aflatoxin M₁ at concentrations ranging from 0.3 to 1.3 ng mL^?1. A second survey using HPLC showed Aflatoxin M₁ at concentrations ranging from 7 to 23 pg mL^?1 in all of the 15 samples collected. 6 of 20 samples of camel milk collected from several sources in Abu Dhabi were also found to contain Aflatoxin M₁ at levels ranging from 0.25 to 0.8 ng mL^?1.     

Optimum Initial Inoculum Levels for Evaluation of Resistance in Tomato to Meloidogyne spp. at Two Different Soil Temperatures

The effects of Meloidogyne incognita or M. javanica at five initial inoculum levels of 20, 100, 200, 1,000, and 2,000 eggs and infective juveniles per seedling on ''Floradade,'' ''Nemarex,'' ''Patriot,'' and ''PI 129149-2(sib)-5'' tomatoes maintained at 25 or 32.5 C were studied. The number of egg masses on roots of the susceptible cultivar Floradade was similar for both species of root-knot nematodes at either 2.5 or 32.5 C soil temperatures. At 25 C, very low numbers of egg masses were produced by both species of root-knot nematodes on Nematex, Patriot, and Lycopersicon peruvianum PI 129149-2(sib)-5. At 32.5 C, the best inoculum level for assessing resistance in these tomato genotypes was 200 eggs and infective juveniles per seedling. With 28 days of incubation, this temperature and inoculum level produced quantitative differences in resistance for both species of Meloidogyne.     

Impact of Planting 'Bell', a Soybean Cultivar Resistant to Heterodera glycines, in Wisconsin

Although the soybean cyst nematode (SCN), Heterodera glycines, has been known to exist in Wisconsin for at least 14 years, relatively few growers sample for SCN or use host resistance as a means to manage this nematode. The benefit of planting the SCN-resistant cultivar Bell on a sandy soil in Wisconsin was evaluated in 1992 and 1993. A range of SCN population densities was achieved by planting 11 crops with varying degrees of susceptibility for 1 or 2 years before the evaluation. Averaged over nematode population densities, yield of ''Bell'' was 30 to 43% greater than that of the susceptible cultivars, ''Corsoy 79'' and ''BSR 101''. Counts of cysts collected the fall preceding soybean were more predictive of yield than counts taken at planting. Yields of all three cultivars were negatively related (P < 0.001) to cyst populations. Fewer (P < 0.01) eggs were produced on ''Bell'' than on the susceptible cultivars. The annual (fall to fall) change in cyst population densities was dependent on initial nematode density for all cultivars in 1992 and for the susceptible cultivars in 1993. Yield reductions induced by the SCN under the conditions of this study indicate that planting a SCN-resistant cultivar in Wisconsin can be beneficial if any cysts are detected.     

Role of patients' view of their illness in predicting return to work and functioning after myocardial infarction: longitudinal study.

OBJECTIVE--To examine whether patients'' initial perceptions of their myocardial infarction predict subsequent attendance at a cardiac rehabilitation course, return to work, disability, and sexual dysfunction. DESIGN--Patients'' perceptions of their illness were measured at admission with their first myocardial infarction and at follow up three and six months later. SETTING--Two large teaching hospitals in Auckland, New Zealand. SUBJECTS--143 consecutive patients aged under 65 with their first myocardial infarction. MAIN OUTCOME MEASURES--Attendance at rehabilitation course; time before returning to work; measures of disability with sickness impact profile questionnaire for sleep and rest, social interaction, recreational activity, and home management; and sexual dysfunction. RESULTS--Attendance at the rehabilitation course was significantly related to a stronger belief during admission that the illness could be cured or controlled (t = 2.08, P = 0.04). Return to work within six weeks was significantly predicted by the perception that the illness would last a short time (t = 2.52, P = 0.01) and have less grave consequences for the patient (t = 2.87, P = 0.005). Patients'' belief that their heart disease would have serious consequences was significantly related to later disability in work around the house, recreational activities, and social interaction. A strong illness identity was significantly related to greater sexual dysfunction at both three and six months. CONCLUSIONS--Patients'' initial perceptions of illness are important determinants of different aspects of recovery after myocardial infarction. Specific illness perceptions need to be identified at an early stage as a basis for optimising outcomes from rehabilitation programmes.     

Cocaine-Induced Changes in NMDA Receptor Signaling

Addictive states are often thought to rely on lasting modification of signaling at relevant synapses. A long-standing theory posits that activity at N-methyl-d-aspartate receptors (NMDARs) is a critical component of long-term synaptic plasticity in many brain areas. Indeed, NMDAR signaling has been found to play a role in the etiology of addictive states, in particular, following cocaine exposure. However, no consensus is apparent with respect to the specific effects of cocaine exposure on NMDARs. Part of the difficulty lies in the fact that NMDARs interact extensively with multiple membrane proteins and intracellular signaling cascades. This allows for highly heterogeneous patterns of NMDAR regulation by cocaine in distinct brain regions and at distinct synapses. The picture is further complicated by findings that cocaine effects on NMDARs are sensitive to the behavioral history of cocaine exposure such as the mode of cocaine administration. This review provides a summary of evidence for cocaine-induced changes in NMDAR expression, cocaine-induced alterations in NMDAR function, and cocaine effects on NMDAR control of intracellular signaling cascades.     

A DNA binding motif coordinating synthesis and degradation in proofreading DNA polymerases.

The functional significance of the conserved motif ''YxGG/A'', located between the 3''-5'' exonuclease and polymerization domains of eukaryotic-type DNA polymerases, has been studied by site-directed mutagenesis in phi29 DNA polymerase. Single substitutions at this region were obtained, and 11 phi29 DNA polymerase mutant derivatives were overproduced in Escherichia coli and purified to homogeneity. Nine mutants showed an altered polymerase/3''-5'' exonuclease balance on a template/primer DNA structure, giving rise to three different mutant phenotypes: (i) favored polymerization (high pol/exo ratio); (ii) favored exonucleolysis (low pol/exo ratio); and (iii) favored exonucleolysis and null polymerization. Interestingly, these three different phenotypes could be obtained by mutating a single amino acid at the ''YxGG/A'' motif. All different phenotypes could be directly related to defects in DNA binding at a particular active site. Thus, a high pol/exo ratio was related to a poor stability at the 3''-5'' exonuclease active site. On the contrary, a low pol/exo ratio or null polymerization capacity was related to a poor stability at the polymerization active site and either a normal or an increased accessibility to the exonuclease active site. These results allow us to propose that this motif, located in the connecting region between the N-terminal and C-terminal domains, has a primary role in DNA binding, playing a critical role in the coordination or cross-talk between synthesis and degradation.