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Biomedical subjects

K Amar

Publications and source records attributed to K Amar.

15 recordsLinked to original sources
PubMed2006

Reduction in urea distribution volume over time in clinically stable dialysis patients.

We have previously shown that, assuming urea distribution volume (V) remains constant for 1 month, ionic dialysance (ID) allows the dialysis dose to be calculated without the need for blood sampling. The aim of this multicenter study was to verify whether the assumption of a constant V can be extended to 1 year. In clinically stable patients receiving thrice-weekly hemodialysis at 13 dialysis centers, V and Kt/V were assessed during three dialysis sessions at baseline and 1 year later using ID as dialyzer urea clearance and the single-pool urea kinetic model. Baseline albumin, hemoglobin, and C reactive protein were prespecified covariates for predicting the change in V over time. Of the 52 enrolled patients, 40 (25 males; age 63.0+/-13.5 years) completed the study. Baseline end-dialysis body weight (62.4+/-13.7 kg) showed a non-significant 1% reduction during follow-up (-0.6+/-2.8 kg; P=0.175), whereas V significantly decreased from 29.0+/-6.8 to 27.4+/-6.0 l (-1.6+/-3.0 l or 4.5%; P=0.002). The reduction in V was greater when baseline albumin was lower (P=0.001) and baseline V was higher (P=0.005). The single-pool K(t)/V calculated using baseline V underestimated the actual value by 0.07+/-0.16 (P=0.008). The slight underestimate of Kt/V during follow-up suggests that annual V evaluations may be sufficient for dialysis dose quantification as the only risk is underestimating the actually delivered dialysis dose. However, the relationship between baseline albumin and the reduction in V over time may have nutritional value, and suggests more frequent V evaluations.

Adolescent↗
PubMed2006

Patient re-training in peritoneal dialysis: why and when it is needed.

The aim of this multicenter, quantitative, observational study was to analyze compliance and re-training needs of patients on peritoneal dialysis (PD) through the assessment of patient knowledge (with a Patient Questionnaire; phase 1) and patient behavior (home visit with a Score Card; phase 2). A total of 353 patients from 11 Italian centers participated in the first phase and 191 patients from nine centers in the second phase. Overall, 66% of questions on the Patient Questionnaire were answered correctly. Correct answers were more frequent in females than males, in patients under 55 years of age, and in those with higher education. The lowest rate of correct answers involved questions related to diet and physical activity (67% and 51%, respectively). Data collected during the home visit showed that 25% of patients were partially compliant with their drug therapy. Twenty-three percent of patients were non-compliant with the exchange protocol procedures, with a significant association between compliance and the incidence of peritonitis, and 11% were non-compliant with the exit-site protocol procedures without a statistically significant correlation to peritonitis. By combining the two evaluations, we found that approximately one-third (29%) of patients needed reinforcement of knowledge and ability to correctly perform PD as related to infection control and 27% for the correct use of drugs. Looking at the combined evaluation of infection control and drug use, results showed that 47% of patients needed re-training. This need for re-training was greater for younger patients (less than 55 years old), patients with lower education degree and patients in the early or late phase of PD therapy (less than 18 months or more than 36 months). Gender and degree of autonomy had no effect on the need for re-training.

Aged↗
PubMed2004

Possible transmission of variant Creutzfeldt-Jakob disease by blood transfusion.

BACKGROUND: Variant Creutzfeldt-Jakob disease (vCJD) is a novel human prion disease caused by infection with the agent of bovine spongiform encephalopathy (BSE). Epidemiological evidence does not suggest that sporadic CJD is transmitted from person to person via blood transfusion, but this evidence may not apply to vCJD. We aimed to identify whether vCJD is transmissible through blood transfusion. METHODS: The national CJD surveillance unit reported all cases of probable or definite vCJD to the UK blood services, which searched for donation records at blood centres and hospitals. Information on named recipients and donors was provided to the surveillance unit to establish if any matches existed between recipients or donors and the database of cases of vCJD. Recipients were also flagged at the UK Office of National Statistics to establish date and cause of death. FINDINGS: 48 individuals were identified as having received a labile blood component from a total of 15 donors who later became vCJD cases and appeared on the surveillance unit's register. One of these recipients was identified as developing symptoms of vCJD 6.5 years after receiving a transfusion of red cells donated by an individual 3.5 years before the donor developed symptoms of vCJD. INTERPRETATION: Our findings raise the possibility that this infection was transfusion transmitted. Infection in the recipient could have been due to past dietary exposure to the BSE agent. However, the age of the patient was well beyond that of most vCJD cases, and the chance of observing a case of vCJD in a recipient in the absence of transfusion transmitted infection is about 1 in 15000 to 1 in 30000.

Blood Donors↗
PubMed2003

An exploratory study of the consistency of balance control and the mobility of people with Parkinson's disease (PD) between medication doses.

OBJECTIVE: To evaluate the consistency of balance control, mobility and perceived difficulties with functional tasks by people on carefully controlled anti-parkinsonian medication programmes, between doses on a single day and across days using standard clinical measures. DESIGN: Small group prospective study. SETTING: A hospital outpatient physiotherapy department. SUBJECTS: Subjects, recruited from a specialist Parkinson's disease (PD) clinic, had to be independently mobile, diagnosed with PD at least five years previously and on a stable drug regime. METHOD: Assessments (timed up and go, functional reach and a tap test) were completed 30 minutes prior to medication and hourly for 4 hours. They were repeated on a second day within a seven-day period. The self-assessment of functional disability was completed during the worst and best periods of the drug cycle. A general linear model (repeated measures analysis of variance) was used to analyse the data. RESULTS: Nine subjects (8 males) with PD (grade III Hoehn and Yahr, average duration of symptoms eight years), average age 72 years, were recruited to the study. Four subjects had worse Hoehn and Yahr scores (grade 4) during the worst phase of the L-dopa cycle. Balance and mobility data did not change significantly over the medication cycle. Tests on day 2 were similar to day 1 with only the tap test showing a significant mean difference (p = 0.02) (2.6, 95% confidence interval (CI) 0.5-4.8). Individuals perceived significantly greater difficulty (mean difference = 7.9, 95% CI 3.6-12.2) (p < 0.001) in achieving functional tasks at the end of dose than peak dose of the medication cycle. CONCLUSION: Measures of balance and mobility remained stable over the cycle. Fluctuations in the perception of difficulties with daily functional tasks were not accompanied by observed fluctuations in performance. The improvement in the mean of the tap test over the days could reflect a learning effect.

Aged↗
PubMed2001

Overview of restless legs syndrome.

Restless legs syndrome is a common movement and sleep disorder, which can significantly reduce quality of life. Restless legs syndrome is probably related to dopamine imbalance and may have a primary or secondary aetiology. It is greatly underdiagnosed, yet potentially treatable.

Anti-Anxiety Agents↗
PubMed1998

Are genetic factors important in the aetiology of leukoaraiosis? Results from a memory clinic population.

OBJECTIVE: To discover whether polymorphism in either the apolipoprotein E (ApoE) or angiotensin-converting enzyme (ACE) genes is associated with leukoaraiosis, white matter lesions visible on neuroimaging of the brain, which is commonly seen in dementia as well as some normal elderly subjects. DESIGN: Prospective study of consecutive patients attending our memory disorders clinic, to examine the relationship between leukoaraiosis and polymorphism of the ApoE and ACE genes. SETTING: Memory disorders clinic in Bristol, UK. PATIENTS: 182 patients attending the memory disorders clinic for investigation of possible dementia of whom 75% were suffering from dementia, 20% from memory impairment but no dementia and in 5% of whom a dementing illness was thought to be unlikely; 38% of all patients had visible white matter lesions and 16% had cerebral infarcts. MEASURES: Patients and/or carers who agreed to participate in the study had their ACE and ApoE genotype determined and their brain CT/MRI scans were assessed by a neuroradiologist, blind to the result of the genotyping, for the presence or absence of white matter low attenuation. RESULTS: There was a significant association between white matter lesions and the DD genotype (p < 0.05), but not the ApoE genotype. However, this relationship with the DD genotype was only significant for patients with a previous infarct. CONCLUSION: Homozygosity of ACE gene deletion polymorphism is a risk factor for white matter lesions when it is associated with cerebral infarction. This suggests that it may be possible to identify subjects who are at greater risk of developing white matter lesions and are at risk of cognitive impairment and possibly dementia.

Aged↗
PubMed1997

The presence of leuko-araiosis in patients with Alzheimer's disease predicts poor tolerance to tacrine, but does not discriminate responders from non-responders.

BACKGROUND: approximately one-third of patients with Alzheimer's disease (AD) respond favourably to the anticholinesterase tacrine, but the drug's usefulness is marred by a high incidence of side-effects. OBJECTIVE: to discover if AD patients with white matter low attenuation (WMLA) represents a subgroup that responds differently to tacrine from those with no WMLA. DESIGN: the results come from a combination of double-blind and open studies. Seventy-two AD patients prescribed tacrine in our centre were divided into two groups according to the presence or absence of WMLA on brain CT scans. We compared the rate of response to and withdrawal from tacrine between the groups. Response was defined as an improvement in the Mini-Mental State Examination score of three or more points at 3 months. RESULTS: 18 of the 72 patients were found to have WMLA. There was no significant difference in the proportion of patients responding to tacrine in each group (28.5% in those with WMLA and 31% in those without), but the rate of withdrawal from tacrine did differ: 11 patients with WMLA (61%) had to be withdrawn prematurely, compared with 14 patients (26%) in the group without evidence of WMLA (P = 0.015). CONCLUSION: AD patients with WMLA can still respond to tacrine, although the rate of withdrawal from treatment is much higher in such patients.

Alzheimer Disease↗
PubMed1996

The diagnosis of vascular dementia in the light of the new criteria.

Recently new criteria for diagnosing vascular dementia (VaD) have been suggested by (a) the State of California Alzheimer's Disease Diagnostic and Treatment Centres (ADDTC) and (b) the NINDS-AIREN group after an international workshop convened by the National Institute for Neurological Disorders and Stroke (NINDS), with support from the Association Internationale pour la Recherche et l'Enseignement en Neurosciences (AIREN). We have retrospectively applied the new criteria to two groups of patients who are thought by us to be suffering from VaD. The first group (20 patients) had a raised Hachinski Ischaemic Score, i.e. 7 or more (mean HIS = 9.5), and a second group (20 patients) with an HIS between 4 and 6 points (mean HIS = 4.9). In group 1, 19 patients fulfilled the ADDTC criteria for probable or possible VaD, compared with 16 patients who fulfilled the NINDS-AIREN criteria. In group 2, 11 patients fulfilled the ADDTC criteria for probable or possible VaD, compared with only five patients who fulfilled the NINDS-AIREN criteria. This suggests that the ADDTC criteria may be more sensitive than the NINDS-AIREN criteria and the HIS. However, post-mortem validation studies of the new criteria are needed to determine if the improved sensitivity of the ADDTC criteria is at the expense of their specificity.

Aged↗
PubMed1996

First steps in building ACME--an admission case-mix system for the elderly.

In the United Kingdom, specialists in Geriatric Medicine usually have a major role in treating acute medical problems of elderly people, in addition to running rehabilitation services and continuing care. The proportion of the different types of patients varies widely from service to service, however, making it difficult for clinicians to compare their performance with that of colleagues. Existing casemix measurement systems are usually designed to deal with a more homogeneous patient group (e.g. rehabilitation, long-stay care) and/or are too detailed for day-to-day use. We describe our attempts to devise a simple casemix system which would be of practical day-to-day use for individual specialists in Geriatric Medicine. We have classified patients according to (1) the acuteness and potential for recovery of their presenting illness and (2) their functional status (based on simple measures of mobility and cognitive impairment). These factors have been incorporated into a three-point score, CMIX, which was capable of explaining 19.5% of the variability in duration of stay in a prospective study of 400 new admissions in two centres. In contrast, age and sex explained only 1% of variability in these patients. The pattern of patient outcome also differed significantly between the three CMIX categories. We also propose a simple graphical method of classifying outcome which should prove useful for audit purposes even when our casemix system is not employed.

Activities of Daily Living↗
PubMed1996

The effect of white matter low attenuation on cognitive performance in dementia of the Alzheimer type.

The effect of leukoaraiosis or white matter low attenuation (WMLA) on cognitive function is not fully understood. We compared the neuropsychological performance of 37 Alzheimer's disease patients with WMLA on CT brain scans with a similar group of 31 Alzheimer's disease patients with no evidence of white matter lesions. Patients with WMLA performed significantly worse on tests of visuospatial function (Cube Analysis test, p = 0.004), and cognitive speed (Kenrick Digit Copying test, p = 0.05) compared to those with no visible white matter lesions. Patients with widespread WMLA performed generally worse in tests of cognitive function than those with frontal or a mixture of frontal and occipital WMLA. This was most significant in the areas of attention (forward digit span, p = 0.003), visual recognition (p = 0.004), and cognitive speed (p = 0.03). There is an association between impaired cognitive performance and the presence of WMLA in Alzheimer's disease patients, with WMLA probably contributing to the cognitive impairment. This is most evident in patients with widespread white matter lesions.

Aged↗
PubMed1996

Genetic determinants and renal mechanisms in essential hypertension.

Human essential hypertension is a polygenic disease whose phenotypic expression is modulated by the environment. Though the kidney could play a major role in the initiation and maintainment of hypertension, many questions remain open. Rat models of primary hypertension provided the substantial information with experiments on kidney cross-transplantation, showing that at least a portion of hypertension could be transplanted with the kidney in all strains where such an experiment has been carried out. Data consistent with those of rats have also been obtained in humans. Many abnormalities in kidney function and cell membrane ion transport have been described in hypertensive rats and humans, but the logical sequence of events from a genetic-molecular abnormality to a cellular abnormality which causes hypertension via a modification of kidney function is difficult to prove. We established this sequence in Milan hypertensive rats using a variety of experimental techniques such as the study of isolated kidney and renal cell function, cell membrane ion transport, cross-immunisation with membrane proteins, molecular biology, genetic crosses and manipulation. Such study led to the identification of a polymorphism in the cytoskeletal protein adducin. Recently, alpha-adducin variants have been associated to both primary hypertension and salt sensitive hypertension. Finally, recent findings strongly support the hypothesis that adducin variants may affect kidney function by modulating the overall capacity of the tubular epithelial cells to transport ions through both a modification in the assembly of actin cytoskeleton, and a modulation of sodium pump activity.

Animals↗
PubMed1995

The relationship between white matter low attenuation on brain CT and vascular risk factors: a memory clinic study.

In order to discover the prevalence of white matter low attenuation (WMLA) in the brain and its relationship to vascular risk factors in our Memory Disorders Clinic patients we assessed brain CT scans of 202 patients referred to our clinic between January 1991 and December 1992. One hundred patients (49.5%) had WMLA, and the prevalence increased with increasing severity of cognitive impairment. It was 12% in patients with no evidence of dementia, 32% in those with isolated memory loss, and 59%) in patients with possible or probable dementia. There was a correlation between WMLA and systolic blood pressure, heart disease, peripheral vascular disease, focal neurological signs on examination and central atrophy on CT. No correlation was found between WMLA and low blood pressure, blood glucose or cholesterol level. Our findings indicate that WMLA probably plays an important role in cognitive impairment, and that thromboembolic rather than haemodynamic factors are probably more important in its pathogenesis.

Aged↗
PubMed1995

Association of the alpha-adducin locus with essential hypertension.

Previous studies on genetic rat hypertension have shown that polymorphism within the alpha-adducin gene may regulate blood pressure. Adducin is a cytoskeletal protein that may be involved in cellular signal transduction and interacts with other membrane-skeleton proteins that affect ion transport across the cell membrane. There is a high homology between rat and human adducin and pathophysiological similarities between the Milan hypertensive rat strain and a subgroup of patients with essential hypertension. Thus, we designed a case-control study to test the possible association between the alpha-adducin locus and hypertension. One hundred ninety primary hypertensive patients were compared with 126 control subjects. All subjects were white and unrelated. Four multiallelic markers surrounding the alpha-adducin locus located in 4p16.3 were selected: D4S125 and D4S95 mapping at 680 and 20 kb centromeric, and D4S43 and D4S228/E24 mapping at 660 and 2500 kb telomeric. Alleles for each marker were pooled into groups. Comparisons between control subjects and hypertensive patients were carried out by testing the allele-disease association relative to the marker genotype. The maximal association occurred for D4S95 (chi 2(1) 13.33), which maps closest to alpha-adducin. These data suggest that a polymorphism within the alpha-adducin gene may affect blood pressure in humans.

Aged↗