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PubMed1977

Hemoglobin S Travis: a sickling hemoglobin with two amino acid substitutions [beta6(A3)glutamic acid leads to valine and beta142 (h20) alanine leads to valine).

Hb S Travis is a previously undescribed sickling hemoglobin with two amino acid substitutions in the beta chain: beta6 Glu leads to Val and beta142 Ala leads to Val. The beta6 Glu leads to Val mutation imparts to Hb S Travis the characteristic properties of sickling hemoglobin, namely its association with erythrocyte sickling, the insolubility of the hemoglobin in the reduced form, and a minimum gelling concentration value identical to Hb S. Unlike Hb S, Hb S Travis exhibits an increased oxygen affinity and a decreased affinity for 2,3-bisphosphoglycerate and inositol hexakisphosphate. In addition, the variant hemoglobin's tendency to autoxidize and its mechanical precipitability suggest that there are conformational differences between Hb S and Hb S Travis.

Alanine↗
PubMed1994

Clinical surveillance of an active fixation, bipolar, polyurethane insulated pacing lead, Part I: The atrial lead.

Since 1989, 168 Telectronics model 330-801 active fixation, polyurethane insulated atrial leads (Accufix) have been implanted at the Mayo Clinic. There were four (2.4%) acute lead related complications, (i.e., perforation, microdislodgment, and pericarditis). Over a median follow-up time of 7.6 months (up to 2.7 years), there were 14 (8.3%) chronic complications, including 1 instance (0.6%) of definite lead failure. Most of these complications were early (within the first month) and transient. Four patients (2.4%) required reoperation for chronic complications. During follow-up, 23% of the examined patients had high pacing thresholds, most at about 3 months after implantation, necessitating high-output programming. The exact mechanism and natural history of this phenomenon should be further investigated.

Adolescent↗
PubMed1995

Instantaneous lead entrapment: an unusual complication of nonthoracotomy implantation of an endocardial defibrillation lead.

Nonthoracotomy implantation of implantable cardioverter defibrillators is performed with transvenous leads that are similar to pacemaker leads and are subject to the same potential problems. We report an unusual complication of lead placement in which an electrode immediately became entrapped in the superior rim of the tricuspid valve, resisting all efforts at removal.

Aged↗
PubMed1999

Atrial sensing and AV synchrony in single lead VDD pacemakers: a prospective comparison to DDD devices with bipolar atrial leads.

INTRODUCTION: Single lead VDD pacing has offered an alternative to DDD systems in patients with isolated AV block. Up to now, however, the relative performance of these pacemaker systems was not systematically compared. METHODS AND RESULTS: Three hundred sixty patients who received either a VDD pacemaker (n = 180) or a DDD device (n = 180) with a bipolar atrial lead were investigated prospectively for a mean period of 30 +/- 13 months. Pacemaker function was analyzed by telemetry, Holter monitoring, and exercise ECG. Time of implantation and fluoroscopy was significantly lower with VDD devices (44.3 +/- 5.1 min vs 74.4 +/- 13.5 min and 4.6 +/- 2.5 min vs 10.3 +/- 5.6 min in DDD pacemakers, respectively). Intermittent atrial undersensing occurred in 23.3% of patients with a VDD pacemaker and in 9.4% with DDD devices (NS). The incidence of atrial tachyarrhythmias did not differ between the VDD (6.7%) and the DDD group (6.1%). Sinus node dysfunction developed in 1.9% of patients, but the vast majority (85.7%) of patients were asymptomatic. There was a tendency for a higher rate of operative revisions in the DDD group (6.1% vs 3.3% in VDD pacemakers, P = 0.15). Cumulative maintenance of AV-synchronized pacing mode was 94.9% in patients with VDD pacemakers and 92.1% with DDD devices (NS). CONCLUSION: With the benefit of a simpler implant procedure, long-term outcome of single lead VDD pacing is equivalent to DDD pacing in patients with AV block and preoperative normal sinus node function.

Aged↗
PubMed1997

Lead Exposure among Adult Temporary Residents in Eastern Europe: Should Blood Lead Levels Be Monitored?

Background: The risk of lead exposure among temporary residents in Eastern Europe is unknown. We monitored blood lead levels (BLLs) of Peace Corps Volunteers serving in Albania, Bulgaria, the Czech Republic, Hungary, Poland, Romania, and Slovakia from June 1991 through June 1994. Methods: BLLs were analyzed before the Volunteers left the United States (Sample 1), at mid-service (median of 15 months in-country, Sample 2), and at end-of-service (median of 22 months in-country, Sample 3). Results: Among 425 study participants who provided at least one follow-up blood sample, BLLs were significantly higher at Samples 2 and 3 compared to the U.S. baseline (paired t-test, p<.0001); however, the mean increase in BLL was only 1.0 ug/dL (range = -9.6 to 10.7). Overall, 74% of Volunteers experienced an increase in BLLs, 24% a decrease in BLLs, and 2% no change in BLLs at Sample 3 compared to their U.S. baseline. The highest increases in BLLs were among Volunteers in Albania, Bulgaria, and Romania (analysis of variance, p<.0001). In addition, men had higher mean increases in BLLs at Samples 2 and 3 compared to women (t-test, p=.017 and.029). Conclusions: The risk of significant lead exposure among our study population was low, and monitoring of BLLs among adult short-term residents in Eastern Europe does not seem to be indicated.

Journal Article↗
PubMed1981

Comparative evaluation of the IBM (12-lead) and Royal Infirmary (orthogonal three-lead) ECG computer programs.

A comparison of two computer programs for ECG interpretation was undertaken. Twelve-lead ECGs from 300 patients with various clinical abnormalities were interpreted at the National Institutes of Health using version 1 of the IBM program and corresponding orthogonal three-lead ECGs were analyzed by the Glasgow Royal Infirmary (GRI) program. Interpretations were compared with respect to the clinical documentation, wherever possible, and with each other directly in the case of diagnostic statements for which non-ECG documentation was not available. The two programs had a similar performance in determining abnormalities such as myocardial infarction and ventricular hypertrophy. However, with respect to conduction defects and ST-T-wave statements, certain discrepancies between the two program performances were revealed. There were 222 disagreements between various diagnostic statements. GRI was judged correct in 119 of these disagreements and IBM in 70. In these 189 cases the disagreement could most often be accounted for by different criteria and/or algorithms in the two programs or by the use of different ECG lead sets. The remaining 33 disagreements had to be classified as inconclusive.

Cardiomegaly↗
PubMed1982

Radiobiological studies with therapeutic neutron beams generated by p+ leads to Be or d+ leads to Be.

Mammalian cells cultured in vitro were used to study the radiobiological characteristics of neutron beams generated by 43 MeV protons on beryllium or 25 MeV deutrons on beryllium. For an unfiltered beam of neutrons generated by 43 MeV p+ leads to Be the relative biological effectiveness was found to be 8-12% higher at a depth of 2 cm than at a depth of 12 cm due to the presence of a large component of low-energy neutrons. The addition of a hydrogenous filter 4 cm thick preferentially removed the low-energy neutrons from the beam and, as a result, the neutron RBE was independent of depth. There was no significant difference in the oxygen enhancement ratio between the filtered neutrons produced by 43 Mev p+ leads to Be and neutrons produced by 25 MeV d+ leads to Be; for both beams the OER value was about 1.6.

Animals↗
PubMed1991

Influence of activation origin, lead number, and lead configuration on the noninvasive electrophysiologic detection of cardiac allograft rejection.

An improved method of cardiac allograft surveillance, less invasive than endomyocardial biopsy (EMB), is required as the scope of cardiac transplantation increases. The correlation between changes in telemetrically recorded intramyocardial electrograms and the degree of rejection was examined. The electrophysiological parameter assessed was the unipolar peak-to-peak amplitude (UPPA), defined as the magnitude of the first, fast negative deflection of the QRS complex in unipolar electrograms. A canine model of intrathoracic heterotopic cardiac transplantation was employed in which each graft was instrumented with four unipolar intramyocardial electrodes (two left ventricle [LV] and two right ventricle [RV]) connected to two telemetric pacemakers. Immunosuppression was begun at operation and continued for a variable period of time following the acquisition of control data (postoperative days 6-10). Graft status was monitored via biweekly EMB. Intramyocardial electrograms were recorded from each lead during sinus rhythm and 36 atrial and ventricular pacing protocols on a daily basis. The daily UPPA was calculated for each rhythm sequence and expressed as percent of control UPPA. EMBs were qualitatively graded and assigned a quantitative rejection score (0 = none; 3 = severe). Criteria for rejection were rejection score (RS) greater than or equal to 0.66 or daily UPPA less than 85% control. Eight animals were included for study and, in all animals, rejection was documented. A total of 30 EMBs were obtained; in 11 EMBs rejection was present by histological criteria. Analysis of grouped UPPA data from all four leads revealed a sensitivity and specificity of 91% and 84%, respectively, in the detection of rejection. Analysis of grouped sinus UPPA data from the two LV leads revealed a sensitivity of 94% and 91%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Studies on the effect of inflammation on rat liver and serum sialyltransferase. Evidence that inflammation causes release of Gal beta 1 leads to 4GlcNAc alpha 2 leads to 6 sialyltransferase from liver.

Turpentine induced inflammation has been shown to elevate liver sialyl- and galactosyltransferase activities (Turchen, B., Jamieson, J.C., Huebner, E., and van Caeseele, L. (1977) Can. J. Zool. 55, 1567-1571; Lombart, C., Sturgess, J., and Schachter, H. (1980) Biochem. Biophys. Acta 629, 1-12). We now report that serum sialyl-, but not galactosyltransferase activities are significantly elevated in turpentine inflammation. A liver slice system is used to demonstrate that liver releases large amounts of sialyltransferase activity into medium after inflammation, whereas only a low level of galactosyltransferase activity is released. Studies with rat and human asialo-alpha 1-acid glycoprotein as acceptors, coupled with the use of lactose to confirm the nature of the linkages formed, showed that Gal beta 1 leads to 4GlcNAc alpha 2 leads to 6 sialyltransferase is released from liver in turpentine inflammation and is mainly responsible for the elevated sialyltransferase activity found in serum. The alpha 2 leads to 6 sialyltransferase is exhibiting the properties of a typical acute phase reactant.

Animals↗
PubMed1980

[Partial trisomy (10pter leads to 10q21) and partial monosomy (21pter leads to 21q21) due to a reciprocal balanced familial translocation (10;21)(q21;q21) (author's transl)].

A newborn infant is reported with a karyotype showing a partial trisomy 10 (10pter leads to 10q21) and a partial monosomy 21 (21pter leads to 21q21) due to a reciprocal balanced familial translocation t(10;21)(q21;q21). This is the first case of partial trisomy 10 for the segment 10pter leads to 10q21.

Chromosome Aberrations↗
PubMed1986

Slow, natural reduction in blood lead level after chelation therapy for lead poisoning in childhood.

Lead poisoning is treated with chelating agents. We report the natural decline of blood lead (Pb-B) concentration after treatment(s) (1967 to 1972) in 74 patients whose maximal Pb-B level ranged from 100 to 471 micrograms/dL (4.83 to 22.73 mumol/L). These longitudinal data (range, nine to 17 years) disclose a predictable decrease in Pb-B levels after treatment that is independent of the maximal Pb-B level before therapy. The correlation between age in months and the logarithm of the Pb-B level was significant, and the equation defined by the regression line allows one to predict Pb-B levels at specific ages after chelation therapy. It is important to recognize the slow, natural decline of Pb-B levels after chelation therapy once the level is stable and below 70 micrograms/dL (3.38 mumol/L). Multiple repeated courses of calcium disodium edetate are unlikely to influence the natural decline of the Pb-B level in asymptomatic children.

Chelating Agents↗
PubMed1980

Abnormal distribution of lead in amyotrophic lateral sclerosis--reestimation of lead in the cerebrospinal fluid.

The lead concentration in CSF was determined by flameless atomic absorption spectrophotometry in 16 ALS patients and 22 control cases. The mean values were 0.69 +/- 0.55 (ALS) and 0.41 +/- 0.37 (controls), P < 0.01. This confirms our earlier findings of raised CSF lead levels in ALS but the present values are lower than previously reported for both ALS patients and controls.

Adult↗
PubMed1987

Lead in ancient human bones and its relevance to historical developments of social problems with lead.

Concentrations of metabolic lead in buried ancient bones are obscured by replacement of calcium in apatite by excessive amounts of soil moisture Pb. Concentrations of metabolic barium in bones are affected in a similar way. Added soil Pb and Ba, expressed as log(Pb/Ca) versus log(Ba/Ca) among various bones at a given burial site, are positively covariant, with about 5-fold more soil Pb added for each unit of added soil Ba. The typical natural metabolic Ba/Ca ratio in contemporary people can be measured unambiguously because it as unaffected by industrial pollution. It applies to ancient people because it has not changed historically. The intercept of the covariance curve for buried bones of a given ancient population at the known metabolic Ba/Ca ratio indexes the corresponding metabolic Pb/Ca ratio in bones of that population. Lead levels which prevailed in Romans appear to have been similar to those in contemporary people, which are approximately 1000-fold above natural levels in humans determined by this method in ancient Peruvians. This indicates that studies of natural biochemical reactions in cells free of industrial Pb should be made, because most present biochemical knowledge is founded on data obtained from systems polluted with Pb 1000 to 100000-fold above natural levels. The 5000 year history of smelting Pb by humans indicates that a system of education fostered by genetically common lower brain center functions operated on hundreds of successive generations in a context of cultural changes invoked by feedback from developments in engineering technologies to give rise to the difference between present typical and prehistoric natural levels of Pb in humans. Archaeological and anthropological studies of early developments in writing, music and metallurgy by ancient Peruvians and Persian peoples should be combined with PET-scan studies of their descendants to discover if, as preliminary archaeological data suggest, the two ancient populations differed on a genetic basis in higher brain functions, yet are indistinguishable as metallurgical engineers. This would demonstrate that higher centers of the human brain did not exercise guiding control, through hundreds of generations, over those developments of engineering technologies which resulted in the extreme pollution of the earth's biosphere with poisonous Pb.

Barium↗
PubMed1981

Effect of phenobarbital on the distribution and excretion of lead in rats acutely poisoned with lead.

Lead (Pb) distribution and excretion after lead injection in rats treated with phenobarbital was examined to investigate the mechanism of the mitigation of Pb toxicity by phenobarbital treatment. Male rats were given 30 mg/kg of phenobarbital s.c. daily for 5 days, and 24 h later a single i.p. injection of 50 mg/kg Pb. The amount of Pb in the liver, red blood cells and heart increased markedly after Pb injection in rats treated with phenobarbital, whereas it decreased in lungs and remained unchanged in kidneys. The excretion of Pb via urine and feces was also suppressed by phenobarbital. From these results, it may be concluded that phenobarbital increased accumulation of Pb in the liver, and suppressed the transfer of Pb to other organs.

Animals↗
PubMed1991

Need for the lead mobilization test in children with lead poisoning.

We evaluated the recommendation of the Centers for Disease Control, that children with moderate lead poisoning undergo the lead mobilization test (LMT) to determine the need for a full course of chelation treatment. Current criteria for selection for this test include a blood Pb concentration (bPb) between 25 and 55 micrograms/dl and an erythrocyte protoporphyrin level greater than 35 micrograms/dl. To determine whether the eligibility criteria could be refined to a smaller group of patients, we compared bPb determinations obtained on the day of the LMT in 198 children with moderate Pb poisoning to the results of the LMT. We found that children with bPb less than 25 micrograms/dl were unlikely to respond to the test dose of calcium disodium ethylenediamine tetraacetate with a Pb diuresis (24/25 patients had low urinary Pb excretion on the LMT). In contrast, 88% of children with bPb greater than or equal to 40 micrograms/dl were likely to excrete sufficient Pb to indicate the need for a full course of chelation. We conclude that the LMT is indicated for children with bPbs between 25 and 40 micrograms/dl. Children with bPb between 40 and 55 micrograms/dl may receive chelation therapy without having an LMT, if the performance of the LMT is not practical. Patients with levels less than 25 micrograms/dl should be followed clinically and removed from further Pb exposure.

Chelating Agents↗
PubMed1982

Tissue distribution of lead in rat pups nourished by lead-poisoned mothers.

Lead accumulation was studied in rats treated with Pb through the dam's milk from birth to weaning. Dams of experimental litters received lead acetate in drinking water, while dams of control litters received a sodium solution. Fluid consumption by dams and pup weight were monitored daily. No differences were seen in the dams' fluid consumption or in mortality or growth rate of pups. Rats were sacrificed after 5, 10, 16, or 21 d of Pb treatment, or 3 and 3.5 mo after weaning. Samples of heart, brain, liver, kidney, intestine, and bone were solubilized in concentration nitric acid and analyzed for Pb by atomic absorption spectrophotometry. Nitric acid digests of blood samples from pups 10 and 21 d old and from animals allowed a Pb-free period of 3-3.5 mo after treatment were also analyzed for Pb concentration. Levels of Pb in all tissues analyzed progressively increased during the first 10 d of treatment. After the Pb-free period only bone Pb concentration remained elevated. The results indicate that treatment of lactating dams is an efficient method of producing chronic Pb exposure of rat pups. The results also provide a means of comparing studies of Pb toxicity in which different treatment paradigms are used.

Animal Population Groups↗
PubMed2004

Current pediatric and maternal lead levels in blood and breast milk in Andean inhabitants of a lead-glazing enclave.

Prenatal and postnatal lead (Pb) exposure may induce neurodevelopmental disabilities in children. As part of an ongoing health-monitoring study, blood lead (PbB) levels were compared in 90 children tested in 2003 (current group) and 166 children tested between 1996 and 2000 (reference group) in Ecuadorian Andean villages with high Pb contamination. The mean PbB level for children in the reference group was 40 microg/dL (range, 6.2-119.1), and significantly higher than the mean PbB level of 25.5 microg/dL (range, 2.1-94.3) for the current group (t test, P = 0.0001). An analysis of variance revealed no significant main effects for age and gender and no significant interaction between age and gender for the current group but a significant age by gender interaction for the reference group (F = 5.96, P = 0.01). Regression analysis revealed a significant correlation (r = 0.258, P = 0.01) between PbB level and age for males but not for females in the reference group. The Pb levels in breast milk from nursing mothers ranged from 0.4-20.5 microg/L (mean, 4.6), and the PbB levels in the breastfeeding mothers ranged from 4.5-35.2 microg/dL (mean, 17.1). The PbB levels of mother-infant pairs ranged from 4.6-27.4 microg/dL for mothers and 3.9-33.5 microg/dL for infants. The results showed significantly reduced PbB levels in children in the study area and suggest that a Pb education and prevention program contributed to the current reduction in Pb intoxication.

Adolescent↗
PubMed1994

Home abatement and blood lead changes in children with class III lead poisoning.

We studied the effect of home abatement on blood lead (PbB) levels in children from central Massachusetts who had not undergone chelation therapy and whose homes were abated between 1987 and 1990, when stricter abatement guidelines were enacted. One hundred and thirty-two children with a mean preabatement PbB of 25.9 micrograms/dL (1.25 mumol/L) were studied: their mean postabatement PbB (up to 1 year later) was 21.1 micrograms/dL (1.02 mumol/L) (P < .001). This reduction correlated with preabatement PbB; 32 of 33 (97%) with preabatement PbB > or = 30 micrograms/dL (> or = 1.45 mumol/L) were lower postabatement, and 64 of 79 (81%) with PbB 20 to 29 micrograms/dL (0.97-1.40 mumol/L) were lower. However, in children with preabatement PbB < 20 micrograms/dL (< 0.97 mumol/L), only seven of 20 (35%) were lower postabatement and, in fact, there was a significant rise in PbB from 16.8 to 19.3 micrograms/dL (0.81 to 0.93 mumol/L) (P = 0.05). Continued improvement in home abatement technology is needed if that strategy is to be effective in achieving the lower PbB levels now mandated in the 1991 Centers for Disease Control guidelines. Primary prevention of the initial blood lead level elevation remains the most desirable strategy.

Age Factors↗