SEARCH · Search PubMed

Results for “LEAD”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,009 records · Page 56Linked to original sources

PubMed1977

Serial enzymatic hydrolysis of cell walls of two serotypes of yeast-form Histoplasma capsulatum with alpha(1 leads to 3)-glucanase, beta(1 leads to 3)-glucanase, pronase, and chitinase.

A serial enzymatic hydrolysis procedure for the partial lysis of Histoplasma capsulatum yeast-form cell walls was described, and its application for the differentiation of two serotypes was evaluated. Cell walls were serially digested with alpha(1 leads to 3)-glucanase and beta(1 leads to 3)-glucanse of Cladosporium resinae, then by Pronase, and then by chitinase. The walls of serotype 1, 2, 3 (61.5% digested) were not susceptible to alpha(1 leads to 3)-glucanse, and they contained 30.3% chitin, thus identifying the strain as chemotype 1 (chem 1). Serotype 1, 4 cells walls (51.6% digested) released 27.3% as glucose after treatment with alpha(1 leads to 3)-glucanse and contained 7.8% chitin, compatible with chemotype 2 (chem 2). In addition to quantitating the monomeric products of enzymolysis, I recovered soluble nondialyzable polysaccharide from the digests of both serotypes.

Cell Wall↗

PubMed1998

Migration and right atrial perforation of an Accufix atrial lead retention wire following partial lead removal during myomectomy.

A 36-year-old man with a history of hypertrophic obstructive cardiomyopathy presented to the emergency room with "stabbing" chest pain. He had undergone dual-chamber pacemaker implantation in 1993 using an atrial lead (Accufix; Telectronics; Englewood, Colo) and a myomectomy in 1996 during which the distal portion of the atrial lead was removed. Digital fluoroscopy revealed that the retention wire had migrated out of the remaining atrial lead and perforated the right atrium. The retention wire was successfully removed percutaneously. The need for complete removal of the retention wire in the Accufix lead at the time of open-heart surgery is emphasized.

Adult↗

PubMed1996

Using the current Brazilian value for the biological exposure limit applied to blood lead level as a lead poisoning diagnostic criterion.

In general, biological exposure limits are only used for the promotion and preservation of workers' health and are not applied for diagnostic purposes. However, the issue is controversial for certain types of occupational poisoning. This paper proposes the utilization of biological exposure limits currently applied to blood lead levels in Brazil as an important criterion for diagnosing occupational lead poisoning. The author argues that contrary to the traditional clinical criterion, one should deal with the diagnostic problem of lead poisoning from an epidemiological perspective, using the current Brazilian value for the biological exposure limit applied to blood lead level as an indicator of high relative risk.

Journal Article↗

PubMed2001

Inappropriate ICD therapy due to lead-related noise in an active fixation ICD lead.

INTRODUCTION: Despite advances in technology, problems with effective ventricular endocardial sensing continue to arise and to result in inappropriate implantable cardioverter defibrillator (ICD) therapies. METHODS AND RESULTS: The patient is a 79-year-old man with ischemic cardiomyopathy and ventricular tachycardia (VT) who received inappropriate ICD therapies due to lead-related noise detection. Noise was created by the distal helix, which was not fully deployed, intermittently contacting the internal guidepost of the lead (CPI, Guidant, model 0155). After the complete deployment of the helix the problem resolved and the pacing parameters remained stable. CONCLUSION: To our knowledge, this is the first confirmed case report of non-physiologic sensing secondary to the incompletely deployed helix of an active fixation defibrillation lead. A design flaw with this lead led to its redesign to avoid noise over-sensing.

Aged↗

PubMed1992

[High-resolution electrocardiography evaluation of late potentials. A comparison between Frank XYZ orthogonal leads and standard precordial electrocardiographic leads].

High-resolution electrocardiography has been used as a non-invasive method for the study of delayed potentials in order to evaluate the risk of the onset of ventricular arrhythmia first in ischaemic cardiopathy and then in various cardiopathies, generally using XYZ orthogonal derivations. The aim of this study was to compare the results obtained with those using standard precordial leads, in particular V4 and V6 leads. A group of 28 patients, males and females, aged between 15 and 55 years of age, was examined. All patients were suffering from different cardiopathies. Subjects with delayed right and left ventricular activation on the surface ECG tracing were excluded from the study. A 60-200 Hertz bandpass filter and time averaging of 300 consecutive complexes were used to analyse tracings. Dual recordings were performed for each patient. The following parameters were examined: total duration of filtered QRS complex and root-mean-square voltage of potentials in the last 40 msec of filtered QRS (RMS). In particular, the comparison between RMS using Frank's method and those obtained using V4 and V6 precordial leads provided a coefficient of correlation of r = 0.91 with p < 0.001 and r = 0.92 with p < 0.001 respectively, and the comparison between QRS obtained using the same method and that obtained using V4-V6 precordial leads gave a coefficient of correlation of R = 0.80, p < 0.001 and r = 0.77 and p < 0.001 respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMedDate not supplied

Diagnostic and therapeutic implications of ST-segment elevation in lead aVR of 12 lead ECG during chest pain.

'aVR' is usually not the preferred lead to diagnose myocardial infarction in clinical settings, it is rather a neglected lead in this context. We describe the case of a 44 year old male who presented with short duration chest pain and ST segment elevation in lead 'aVR'. His left heart catheterization showed left main stem equivalent disease and totally occluded right coronary artery. Patient underwent emergency coronary artery bypass-grafting with favorable outcome. This case highlights the significance of ST segment elevation in lead aVR during chest pain both in diagnosis and management of patients with acute coronary syndrome.

Adult↗

PubMed1996

Indirect measurement of tidal volume by multi-lead electrocardiograms: effect of filtering, deep breath, lead and posture.

We examined a new method for estimating tidal volume from the electrocardiogram (ECG) in order to dispense with the need for sensors used exclusively for tidal volume measurement. The direction of the vector loop in the QRS complex (DVL) was defined as the direction of the diagonal line of the rectangle which circumscribed the vector loop obtained from two orthogonal leads. Two leads of the ECG were transformed into the orthogonal leads using Einthoven's triangle. The peak-to-peak change in the direction (the change in the DVL) was highly correlated with tidal volume. Low-pass filtering of the ECG produced a better correlation between tidal volume and the change in the DVL, when the cutoff frequency was set at 20-45 Hz. A tidal volume of less than 1.21 was correlated more highly with the change in the DVL than a tidal volume of more than 1.21 A combination of leads I and III produced the best correlation between tidal volume and the change in the DVL, compared with other combinations. The posture of the subject had some effects on the slope of the linear regression between tidal volume and the change in the DVL.

Electrocardiography↗

PubMed2000

A meta-analysis for neurobehavioural results due to occupational lead exposure with blood lead concentrations <70 microg/100 ml.

The size of performance effects caused by exposure to inorganic lead was determined by a meta-analytical procedure. Twenty-two studies covering exposure conditions of <70 microg/100 ml blood lead concentration were considered as to whether the methods of recording performance deficits were comparable. As a consequence of different test procedures and insufficient documented test results only 13 tests out of 12 studies could be included in the analysis. For the tests Block Design, Logical Memory and Santa Ana performance deficits were found, which may be interpreted as 'small' effects in accordance with a convention for evaluating effect sizes. For the example of Block Design it could be shown that these effects are nevertheless serious. The extent of the exposure related decrease of performance was comparable with those changes of performance which can be expected during aging of up to 20 years. Subsequently, a blood lead concentration of 70 microg/100 ml cannot be considered as a safe limit against long-term decreases of psychological performance.

Adult↗

PubMed1997

Extensive lead exposure in children living in an area with production of lead-glazed tiles in the Ecuadorian Andes.

We have determined the concentrations of lead (Pb), cadmium (Cd), and mercury (Hg) in the blood of children living in two Andean villages in Ecuador with many family-owned cottage-type industries using Pb from discarded car batteries and occasionally, utility batteries containing Cd and Hg for the production of glazed tiles. The battery metals are ground together with water to a suspension, which is applied manually onto the tiles and then fused at about 1,200 degrees C in sawdust-fired kilns. Children aged 4-15 years were recruited from the schools with the assistance of the school-teachers. Children from homes with and without tile-glazing activities were to be included. Blood metal concentrations were determined by inductively coupled plasma mass spectrometry (ICP-MS). The children had extremely high blood lead concentrations (B-Pb), which ranged between 100 and 1,100 micrograms/l (median 510 micrograms/l, n = 82). Children from families engaged in tile-glazing production had significantly higher B-Pb (median 600 micrograms/l) than those living in homes with no such activity (median 210 micrograms/l), although the B-Pb of the latter were nonetheless clearly elevated. B-Cd and B-Hg were low (medians 0.25 microgram Cd/l and 1.6 micrograms Hg/l, respectively), indicating that the exposure from utility batteries containing Cd and Hg was low. The blood hemoglobin concentrations decreased significantly with rising B-Pb, indicating an effect on the heme synthesis. This was supported by a marked increase in the blood concentration of protoporphyrins with increasing B-Pb. It can be concluded that children from families with cottage industries producing glazed tiles are at risk for severe health effects due to high lead exposure.

Adolescent↗

PubMed1984

The relationship between air lead and blood lead in children: a critical review.

A review is given of community studies from which the relationship between air lead and blood lead in children of varying ages can be estimated. The review covers nineteen different studies which were carried out in ten different countries. The blood lead/air lead relationship is denoted with the symbol "alpha'. It is concluded that for children, a wide range of alpha-values can be estimated from the data in the different studies. Most values center on 3-5 rather than the 1-2 which is usually reported from adults. However, adjustment for confounders has been absent or incomplete in most, if not all studies. Most alpha-estimates thus have to be viewed with caution.

Adolescent↗

PubMed1990

Using unstimulated urinary lead excretion to assess the need for chelation in the treatment of lead poisoning.

To determine whether unstimulated urine samples could be used to identify children needing chelation therapy for lead poisoning, we compared urinary lead excretion with and without chelation. A convenience sample of 39 children was admitted to a pediatric clinical research center for therapeutic chelation. Urine was collected for 24 hours on 2 consecutive days. Edetate disodium calcium, 1000 mg/m2, was given intramuscularly in two divided doses on the second day. Significant correlations existed between urinary lead excretion (PbU) on the control day at 12- and 24-hour collection intervals and on the first day of chelation (p less than 0.0001). Published criteria for positive edetate disodium calcium provocative tests were used to calculate corresponding cutoff points for unstimulated 24-hour PbU. Resultant PbU values ranged from 10.4 to 35.6 micrograms (0.05 to 0.17 mumol). When PbU was expressed in terms of creatinine excretion, cutoff points of 0.06 and 0.19 microgram PbU/mg creatinine were determined, making possible the use of random unstimulated samples to assist in the identification of children in need of chelation.

Chelation Therapy↗

PubMed2006

The effect of covariance between the K alpha and the K beta lead peak concentrations on the uncertainty in the result of in vivo (109)Cd KXRF bone lead measurement.

The effect of covariance between the K alpha and K beta lead peak concentrations on the uncertainty in the (109)Cd K x-ray fluorescence measurement of lead in bone is addressed here. It is commonly believed that this covariance arises as a result of the mutual dependence of the ratios of x-ray to coherent amplitudes on the same coherent peak amplitude. Previous work assumes statistical independence between spectral quantities of interest, crudely estimates the uncertainties in the lead peak concentrations, and suggests that the effect of covariance on the measurement uncertainty is small and can be ignored. Consequently, the current method followed by most laboratories reports the measurement uncertainty as if the fluctuations in the measured peak concentrations were independent. The robustness of such assumption, however, is undermined by existing epidemiological data. This paper assesses the magnitude of the covariance effect, using a method based on the observed significant correlations between the ratios of x-ray to coherent peak amplitudes in series of repeat phantom measurements. The revised uncertainties following this approach can exceed the uncertainties estimated by the accepted method by as much as 40%, which suggests a much stronger effect of covariance on the measurement uncertainty than previously reported.

Analysis of Variance↗

PubMed1989

Blood-lead levels and children's behaviour--results from the Edinburgh Lead Study.

The effect of blood-lead on children's behaviour was investigated in a sub-sample of 501 boys and girls aged 6-9 years from 18 primary schools within a defined area of central Edinburgh. Behaviour ratings of the children were made by teachers and parents using the Rutter behaviour scales. An extensive home interview with a parent was also carried out. Multiple regression analyses showed a significant relationship between log blood-lead and teachers' ratings on the total Rutter score and the aggressive/anti-social and hyperactive sub-scores, but not the neurotic sub-score when 30 possible confounding variables were taken into account. There was a dose-response relationship between blood-lead and behaviour ratings, with no evidence of a threshold.

Aggression↗

PubMed1991

Detection and cellular localization of lead by electron probe analysis in the diagnosis of suspected lead poisoning in rhesus monkeys.

Lead poisoning of unknown source was diagnosed histologically in 2 rhesus monkeys (Macaca mulatta) by finding acid-fast intranuclear inclusion bodies in the epithelial cells of renal cortical tubules. The presence of lead in the inclusions was determined by scanning electron microscopy/energy dispersive x-ray analysis using sections from paraffin embedded tissues. This observation indicates the usefulness of this technique for the detection and cellular localization of lead in tissues, even from archival material.

Animals↗

PubMed1987

Unusually high circumpulpal lead concentrations as valid evidence of lead intoxication.

A case is reported of a 59-year-old male who had been employed continuously as a motor technician for 32 years. During the latter period of his employment he gradually developed a number of the signs and symptoms typically manifested by persons suffering from lead intoxication. Five years after the termination of his employment, the lead content in the circumpulpal dentine of 2 of his teeth was determined and found to be more than 7 times higher than that of the controls. Thus, the probability of lead intoxication is supported very strongly.

Dentin↗

PubMedDate not supplied

Environmental lead contamination and pediatric lead intoxication in an Andean Ecuadorian village.

Environmental lead (Pb) contamination was measured in samples of soil and locally grown food produce in a remote Ecuadorian village where Pb glazing of ceramics is the local cottage industry. The Pb concentration levels of local soil samples collected at varying distances from a cluster of backyard Pb baking kilns were 29,213 ppm (microg/g) at 0.001 km, 172 ppm at 0.005 km, 81 ppm at 0.01 km, 55 ppm at 1 km, 19 ppm at 2 km, and 1.4 ppm at 6 km, significantly higher than levels in control soil samples from non-Pb-glazing reference areas. Samples of locally grown food produce were also found to be Pb contaminated. Venous blood samples from 166 schoolchildren (ages 4 months to 15 years) in the study area and 56 children in the reference area showed mean blood lead levels of 40.0 microg/dl (SD: 24.5; range: 6.2. - 119.1 microg/dL) and 6.6 microg/dL (SD: 3.4; range: 1.9 - 18.1 microg/dL), respectively, which were significantly different (p = 0.0001). The Pb levels in milk from breastfeeding mothers ranged from 1.44 to 39 ng/g. Lead isotope ratios of the children's blood and of samples of village soil revealed a common Pb source or "fingerprint."

Adolescent↗

PubMed1974

Significance of plasma lead levels in normal and lead-intoxicated children.

Plasma lead (Pb) levels have been measured in normal and lead-intoxicated children, newborns, and children with sickle cell disease. The results in all groups were contant over a wide range of red cell Pb concentration. These results support the thesis that the red cell represents a large repository for Pb, maintaining plasma Pb concentration within closely defined limits, and that methods other than measurements of plasma Pb will be necessary to uncover a presumably dynamic transport system between red cell and plasma. Indeed, we have demonstrated in vitro that ionized calcium (Ca(2+)) lowers red cell Pb content according to a linear dose-response curve. Ca(2+) may thereby control Pb transport from red cell to plasma, and fluctuations in the concentration of Ca(2+) in serum and extracellular fluid may influence the toxic activities of Pb. In bone organ culture, changes in the concentration of Ca(2+) and phosphate in the medium alter the release of previously incorporated (210)Pb from fetal rat bones in response to parathyroid hormone (PTH). Therefore, both PTH and the ionic milieu of the medium apparently regulate bone Pb metabolism.We would expect that understanding further the dynamics of Pb transport in plasma and bone may lead to a more exact definition of the real hazards of low level Pb toxicity in children.

Anemia, Sickle Cell↗

PubMed1999

Is universal screening for lead in children indicated? An analysis of lead results in Augusta, Georgia in 1997.

Pediatricians have a dilemma about whether they should do universal or targeted screening for lead in children. In order to determine whether we should continue our institution's present policy of universal screening, we analyzed 962 lead samples obtained by routine screening in the calendar year 1997, 83 children (8.6%) had elevated levels (over 10 mcg/dl) by capillary samples; of the 57 children who had follow up tests by venipuncture, 35 had abnormal levels making the incidence of elevated leads in our screened children 3.6%. Most of the abnormal levels were in African-American children living in two downtown zip codes. Based on recent AAP recommendations, in our community, targeted screening should replace universal screening.

Child↗