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Biomedical subjects

J Lambert

Publications and source records attributed to J Lambert.

At least 37 records · Page 2Linked to original sources
PubMed1997

The structural components of music perception. A functional anatomical study.

This work explores the cerebral structures involved in the appreciation of music. We studied six young healthy subjects (right handed, French, without musical talent), using a high resolution PET device (CTI 953B) and 15O-labelled water. In three tasks, we studied the effects of selective attention to pitch, timbre and rhythm; a final task studied semantic familiarity with tunes (considered as divided attention for pitch and rhythm). These four tasks were performed on the same material (a tape consisting of 30 randomly arranged sequences of notes). We selected a paradigm, without a reference task, to compare the activations produced by attention to different parameters of the same stimulus. We expected that the activations recorded during each task would differ according to the differences in cognitive operations. We found activations preferentially in the left hemisphere for familiarity, pitch tasks and rhythm, and in the right hemisphere for the timbre task. The familiarity task activated the left inferior frontal gyrus, Brodmann area (BA) 47, and superior temporal gyrus (in its anterior part, BA 22). These activations presumably represent lexico-semantic access to melodic representations. In the pitch task, activations were observed in the left cuneus/precuneus (BA 18/19). These results were unexpected and we interpret them as reflecting a visual mental imagery strategy employed to carry out this task. The rhythm task activated left inferior Broca's area (BA 44/6), with extention into the neighbouring insula, suggesting a role for this cerebral region in the processing of sequential sounds.

Adult↗
PubMed1997

Acute human immunodeficiency virus type 1 disease as a mononucleosis-like illness: is the diagnosis too restrictive?

The purpose of this study was to describe the frequency and duration of clinical features at the time of acute human immunodeficiency virus type 1 (HIV-1) disease in 218 patients with documented symptomatic primary HIV-1 infection. The mean duration of acute HIV-1 disease was 25.1 days (median, 20.0 days) and did not differ by gender, age, and risk factor. The frequency and mean duration of clinical features occurring in >50% of patients were as follows: fever, 77.1% and 16.9 days; lethargy, 65.6% and 23.7 days; cutaneous rash, 56.4% and 15 days; myalgia, 54.6% and 17.7 days; and headache, 50.9% and 25.8 days. Only 15.6% of patients presented with a typical mononucleosis-like illness (MLI) defined as fever, pharyngitis or sore throat, and cervical adenopathy, and 10% had no features of an MLI. A meningitis-like syndrome occurred in 20 patients (9.2%). Acute HIV-1 disease is more diverse than previously reported, and the absence of fever or other MLI features does not rule out acute HIV-1 disease.

Acute Disease↗
PubMed1997

Experimental reproduction of polymorphous light eruption and benign summer light eruption by whole-body UVA irradiation.

The entity 'benign summer light eruption' (BSLE) has been introduced to make a clinical subdivision in the heterogeneous group of polymorphous light eruptions (PLE). Provocation tests for PLE are not always easy to perform and require expensive apparatus. Our purpose was to evaluate a provocation test that could be readily done by a dermatologist with a UVA cabin. Provocation tests are currently required in order to obtain a financial contribution from the social security services in Belgium. In addition, we were interested in determining whether the results of the provocation test would permit us to differentiate between the clinical entities of BSLE and PLE. We studied the efficacy of whole-body UVA irradiation for BSLE and PLE patients. A total of 45 patients was tested, of whom 26 were diagnosed as having BSLE and 19 PLE. In the BSLE group, 24 patients (92%) presented lesions. In the PLE group, 15 patients (79%) had a reaction, but 3 had a positive UVB test. The mean dose to induce lesions was 65.96 J/cm2 for the BSLE group and 52.86 J/cm2 for the PLE group. We conclude that the whole-body UVA test is a high-performance provocation test for both BSLE and PLE patients although it cannot differentiate the two entities from one another.

Adolescent↗
PubMed1997

Sodium, blood pressure, and arterial distensibility in insulin-dependent diabetes mellitus.

We investigated 24-hour ambulatory blood pressure and arterial distensibility, a marker of biophysical vessel wall properties, in 32 normoalbuminuric type I diabetic patients and 32 healthy control subjects on diets containing 50 mmol and 200 mmol sodium per day. The increase in daytime diastolic blood pressure from 50 to 200 mmol sodium was significantly higher in the diabetic patients than in the control subjects (2.3+/-4.9 versus 0.2+/-3.7 mm Hg, P<.05). On a high sodium regimen, femoral artery distensibility was decreased in the diabetic patients compared with the control subjects (19.2+/-7.6 versus 24.1+/-9.3 10[-3]/kPa, P<.05). Angiotensin-converting enzyme inhibition in the diabetic patients on a high sodium diet decreased daytime diastolic blood pressure and increased femoral artery distensibility. The blood pressure decrease in response to angiotensin-converting enzyme inhibition correlated significantly with the blood pressure increase to sodium (for 24-hour systolic and diastolic blood pressure, r=.72, P<.001 and r=.76, P<.001). In addition, we found that in the diabetic patients on a high sodium diet, the renal blood flow response to exogenous angiotensin II was not bimodally distributed, as is the case in essential hypertension, in which a subgroup of the patients are characterized by sodium sensitivity of the blood pressure and an abnormal renal blood flow response to exogenous angiotensin II ("nonmodulator phenotype"). These results show that blood pressure in insulindependent diabetes mellitus is sodium sensitive, but that this is not related to the nonmodulator phenotype, and suggest that in IDDM a relatively high sodium intake may be a factor that predisposes to the development of diabetic vascular disease.

Adult↗
PubMed1997

The acute effect of hyperglycaemia on vessel wall properties.

Arterial distensibility is a marker of functional and structural vessel wall properties. A decreased distensibility is an important risk factor for cardiovascular disease. In insulin-dependent diabetes mellitus of short duration, arterial stiffness has been reported to be increased, decreased or the same as in healthy control subjects. The influence of acute hyperglycaemia on arterial stiffness is unclear and might be one of the factors responsible for the divergent results which have been observed. We investigated arterial distensibility locally in the carotid artery during hyper- and normoglycaemia using a glucose clamp technique. Eleven healthy normotensive men underwent both a hyperglycaemic and a euglycaemic clamp on separate days. Before and after 2 h of clamping, arterial diameter (D) and change in arterial diameter during the heart cycle (dD) were measured with a non-invasive vessel wall movement detector system. Blood pressure (BP), pulse pressure (dP) and heart rate (HR) were recorded with a semi-automated device. Distensibility coefficients (DC), reflecting the intrinsic vascular wall elasticity, and compliance coefficients (CC), reflecting the buffering capacity of the vessel, were calculated from D, dD and dP. (DC = 2*dD/ D*dP, CC = pi*dD*D/2*dP). There were no significant differences between the hyperglycaemic and the euglycaemic clamp for D, DC and CC. These results suggest that an acute systemic hyperglycaemia is not responsible for changes in diameter, distensibility and compliance of the carotid artery.

Carotid Arteries↗
PubMed1997

Understanding the intention of gay and bisexual men to take the HIV antibody test.

This study offers an explanation for the intention of 1,512 gay and bisexual men to be tested for the HIV antibody. Participants were recruited through 125 gay-identified venues (bars, bathhouses, community dances) across Canada. Self-administered questionnaires assessed respondents' intention to take the test in the next year, predictor variables (e.g., attitudes, the perceived social norm of the gay community, perceived behavioral control, and other constructs such as reasons for not being tested and importance of aspects of the test such as confidentiality), and sociodemographic variables. For this analysis, two groups were formed: men who had taken the HIV test in the past with negative or unknown results (Group A) and men who had not taken the test (Group B). The proportions of men who intended to take the test in the next year were 84.8% and 53.3% for groups A and B, respectively. For both groups, logistic regression indicated that the most important factors explaining intention were attitudes toward taking the test and perceived behavioral control. Additional variables specific to each group also contributed to explain intention. Thus, to enhance test-seeking among this population requires a consistent program of health education and facilitative policies.

AIDS Serodiagnosis↗
PubMed1997

Endothelium-dependent vasodilatation and distensibility of large arteries in chronic haemodialysis patients.

BACKGROUND: Cardiovascular mortality is increased in chronic haemodialysis (HD) patients and is not completely explained by common cardiovascular risk factors. Hyperhomocysteinaemia and chronic HD per se may play a role, because these factors may adversely affect endothelial function and distensibility of conduit arteries, which are important determinants of the risk of atherosclerosis, thrombosis and cardiac hypertrophy. METHODS: A vessel wall movement detector system was used to investigate endothelium-dependent, flow-mediated and endothelium-independent, glyceryl trinitrate-induced vasodilatation in the brachial artery and compliance and distensibility coefficients (CC and DC) in the common carotid artery in 28 chronic HD patients and 28 control subjects. RESULTS: Endothelium-dependent, but not endothelium-independent, vasodilatation was markedly reduced in the HD group (3.7 +/- 1.1 vs. 9.7 +/- 1.2%; P = 0.001). The DC was reduced only in a subgroup of patients aged < 50 years: 16.9 +/- 1.5 vs. 22.4 +/- 2.0 10(-3)/kPa (P = 0.032) and was not related to endothelium-dependent vasodilatation. CC did not differ between the groups. Plasma total homocysteine was elevated in the HD patients, but was neither related to endothelium-dependent vasodilatation, nor to DC. CONCLUSION: Chronic renal failure and (or) chronic haemodialysis are associated with impaired endothelium-dependent vasodilatation, which may reflect an increased susceptibility for the development of atherosclerosis and thrombosis.

Adult↗
PubMed1996

Agraphia in Alzheimer's disease: an independent lexical impairment.

This study was conducted to delineate the pattern of the writing impairments in 12 patients with Alzheimer type dementia. The patients performed writing tasks involving regular and irregular words and nonwords given by dictation as well as a decision test composed of printed words and pictures requiring phonologic, lexical, and semantic processing. Writing from dictation demonstrated a predominant, but nonisolated, lexical deficit. In order to better evaluate this lexical disorder, the correlation between the dictation writing scores and the decision task scores was analyzed. No significant correlation was found among scores for irregular words, phonologically plausible errors, and scores of the lexical or semantic decision tasks, but there was a significant correlation among scores for the nonwords, nonphonological spelling errors, and scores of the phonologic decision task using printed words. These results would suggest that the "lexical" deficit in agraphia, i.e., difficulty in retrieval or loss of the spelling representations of words, is independent of the lexical or semantic capacities involved in other modalities.

Aged↗
PubMed1996

Clinical and genetic study of chronic (types II and III) childhood onset spinal muscular atrophy.

We have conducted a retrospective study of 63 patients affected by chronic forms of spinal muscular atrophy (SMA) to better document the natural history of this disease. Thirty-nine patients had type II and 24 type III SMA. These patients had manual muscle testing (MMT) and forced vital capacity (FVC) studies done every six to 12 months over follow up period ranging from six to 140 months. A decline in FVC was seen in both types of SMA but there was no significant change in MMT in either group. Genetic studies were also done in a subset of 17 families (23 patients) included in this study. Homozygous deletions in the telomeric survival motor neuron (SMN) and the neuronal apoptosis inhibitory protein (NAIP) genes were observed in 100% and 11.8% of the patients tested respectively.

Adolescent↗
PubMed1996

Fatigue effects on muscle excitability.

Repeated isometric or shortening contractions of skeletal muscle cause muscle fatigue but several prior studies have reported an apparent absence of muscle fatigue when humans performed up to 70 lengthening contractions. We pursued the hypothesis that perhaps muscle excitability is a factor that aids force preservation with repeated eccentric actions. Soleus compound muscle action potential (M-wave) latency, peak-to-peak amplitude (PPA), duration, and area under the curve were examined in 12 subjects (mean age 24.3 y) over 4 testing days that included: no exercise, isometric exercise (neutral ankle angle), isokinetic (0.5 rad.s-1) concentric and eccentric exercise of the plantar flexors in the seated position on a Biodex dynamometer. Supramaximal shocks were delivered to the tibial nerve in the popliteal fossa at baseline (3 shocks, 1 min apart), during exercise (1 shock-after each of 5 bouts/10 contractions), and during 10-min recovery. From initial to final contractions, concentric, isometric, and eccentric fatigue was -32, -41 and + 2% (Condition by Trial Interaction, F2,22 = 25.1, p = 0.000). No changes occurred in latency or duration (p > 0.05), but PPA (Condition by Time interaction, F51,561 = 3.7, p = 0.000) increased during isometric and eccentric exercise and remained elevated during recovery. Area increased (F51,561 = 3.1, p = 0.000) significantly during all three exercise conditions and approximated baseline by minute 8 of recovery. It was concluded that although the potentiation of the action potential of individual muscle fibers seems to be the common mechanism underlying the increase in muscle excitability during plantar flexion exercise, it is possible that different factors could cause such a non-specific response.

Action Potentials↗
PubMed1996

Sexual risk and HIV-testing behaviour by gay and bisexual men in Canada.

Behavioural epidemiology is an important aspect of HIV research, particularly among marginalized populations where measurement of rates of infection have not been conducted. This Canadian study provides a country-wide analysis of the characteristics and behaviours of gay and bisexual men, and examines the influence of geographic, socio-demographic and lifestyle influences on sexual behaviour and test-seeking. A purposive sample of 4,803 men was recruited through gay-identified venues. In order to provide national representation seven sampling strata were defined. Data were collected by self-completed questionnaire. A three-level hierarchical logistic regression analysis is used to model two behaviours, unprotected anal intercourse and test-seeking. The results showed that, nationally, 22.9% of respondents reported at least one episode of unprotected anal intercourse in the previous 3 months, and 63% had been tested. Characteristics and behaviours of men varied across the country. Geographic differences appear to be less important in explaining unprotected anal intercourse than test-seeking. In conclusion, policy, programmes and social environment appear to exert an important influence on test-seeking, whereas cultural and psychosocial dimensions appear to have a greater influence on sexual behaviour.

AIDS Serodiagnosis↗
PubMed1996

Evaluation of two-point discrimination in children: reliability, effects of passive displacement and voluntary movements.

Two-point discrimination (2-PD) thresholds were studied at three sites (tip of index finger, thenar eminence, external malleolus) and under various testing conditions (dynamic vs static, with and without displacement of instrument on skin; and active vs passive, with and without voluntary movement of subject) in 47 healthy children between 6 and 13 years of age. Reliability was fair to moderate, with slightly better perception (learning effect) during the second testing session. The threshold values of these children were similar to those of adults. For the passive conditions, the threshold values were lower for dynamic than for static tests at all sites. For the active condition at the index finger, there were no differences between dynamic and static values and there was no active/passive main effect. It is concluded that: (1) the hand is more sensitive than the ankle, with the finger being the most sensitive area, (2) the 2-PD test procedure used was most reliable at the index finger and least reliable at the external malleolus and (3) displacement of the instrument on the skin can improve 2-PD threshold values in children but the discrimination thresholds are not changed by active movement of the subject.

Adolescent↗
PubMed1996

A survey of midwives in Quebec: what are their similarities and differences?

BACKGROUND: Until recently, Canada was the only industrialized country that had not legalized midwifery. In the province of Quebec the government adopted a law to evaluate midwifery in eight pilot projects before generalizing the practice. This study examined the similarities and differences among midwives in Quebec. METHODS: Using data from a 1991 mail survey, we compared 31 nurse-midwives, 12 professional midwives, and 27 lay midwives to assess professional background and opinions about selected maternity care issues and aspects of future midwifery practice, such as midwife training options, responsibilities, setting for midwifery care, relationship to other maternity caregivers, autonomy, and control over their profession. RESULTS: Midwives largely shared the same philosophy of care but had different viewpoints on two main professional aspects: compared with professional midwives and nurse-midwives, lay midwives preferred to deliver antepartum, intrapartum, and postpartum care at a client's home or an independent birthing center; like professional midwives, they rejected nursing as a prerequisite to midwifery training. Other interrelated personal, social, political, and legal factors were also associated with different beliefs. CONCLUSIONS: Despite the differences among the three groups, the process under way in Canada is to recognize a single profession of midwife. Creating a unified profession is a challenge that Canadian midwives with different backgrounds face in the 1990s.

Health Knowledge, Attitudes, Practice↗
PubMed1996

Greater initial adaptations to submaximal muscle lengthening than maximal shortening.

The purpose of this study was to compare the short-term strength and neural adaptations to eccentric and concentric training at equal force levels. Forty-two sedentary women (age = 21.5 yr) were ranked based on the initial quadriceps strength score, and trios of subjects were randomly assigned to either an eccentric (n = 14), a concentric (n = 14), or a nonexercising control group (n = 14). Training involved a total of 824 eccentric or concentric quadriceps actions at 1.05 rad.s-1 administered in four sets of 6-10 repetitions, four times per week for 6 wk. Before and after training, all subjects were tested for unilateral maximal isometric and eccentric and concentric actions at 1.05 rad.s-1 and for a 40-repetition eccentric and concentric fatigue series of the left and right quadriceps. Surface electromyographic activity of the vastus lateralis and medialis was monitored during testing. Concentric training increased concentric (36%, P < 0.05), isometric (18%, P < 0.05), and eccentric strength (13%), and eccentric training increased eccentric (42%, P < 0.05), isometric (30%, P < 0.05), and concentric (13%) strength. Eccentric training improved eccentric and isometric strength more (P < 0.05) than did concentric training. The electromyographic adaptations were greater with eccentric training. Cross-education was 6%, and neither training mode modified fatigability. The data suggest that training of the quadriceps muscle with submaximal eccentric actions brings about greater strength adaptations faster than does training with maximal-level concentric actions in women. This greater adaptation is likely to be mediated by both mechanical and neural factors.

Adaptation, Physiological↗