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At least 37 records · Page 2Linked to original sources
PubMed1979

"Proenamel leads to enamel leads to polypeptides": a concept.

Our laboratory is interested in determining the number of enamel protein gene products which characterize the ameloblast phenotype, and to what extent these proteins are degraded as a function of enamel maturation. Many investigators have reported a large number of heterogeneous proteins within the enamel matrix (Eggert, Allen and Burgess, 1973; Weidmann and Eyre, 1971). One explanation for this apparent heterogeneity may be the uncertain age of the analyzed enamel matrix; specimens may have undergone degradative processes associated with enamel maturation. To overcome this difficulty, our laboratory selected 26-day embryonic New Zealand White (NZW) rabbit incisor and molar tooth organs to isolate enamel protein(s). At this developmental stage it is possible to identify newly-secreted enamel matrix proteins.

Amelogenesis↗
PubMedDate not supplied

Renal effects of repeated administration of calcium disodium ethylenediaminetetraacetate during excessive exposure to lead in rats.

The renal effects of repeated administration of EDTA were studied in rats given 0.5% lead as lead acetate in drinking water for 24 weeks. Repeated treatment of lead toxic rats with EDTA during continuous exposure to lead reduced blood lead levels and brain and bone lead but not to a statistically significant level (p greater than 0.05). Liver lead concentration in the EDTA treated, lead exposed rats changed only slightly upward, but kidney lead levels decreased greatly when compared to lead exposed, non-EDTA treated rats, (group IV vs. group III), (p less than 0.05). Light and electron microscopy of kidneys of lead treated rats showed evidence of an early interstitial nephropathy characterized by peritubular fibrosis and variation in size of tubular cells. Nuclei of renal tubular cells of lead exposed rats had inclusion bodies, but these were not present in lead exposed, EDTA treated rats. The present study suggests that repeated treatment of rats with EDTA during continuous exposure to lead reduces renal lead concentration but does not significantly influence the progression of lead induced nephropathy.

Animals↗
PubMed2026

Comparison between measured and synthesized posterior lead electrocardiograms during percutaneous coronary intervention-induced myocardial ischemia.

BACKGROUND: Posterior/inferolateral myocardial ischemia is frequently underrecognized on standard 12&#x2011;lead electrocardiography (ECG). Synthesized posterior leads derived from the standard 12&#x2011;lead ECG have been proposed as an alternative to directly measured posterior leads; however, their accuracy under controlled ischemic conditions has not been fully validated. METHODS: We prospectively enrolled 26 consecutive patients undergoing percutaneous coronary intervention (PCI) in whom simultaneously recorded measured and synthesized posterior lead ECGs (V7-V9) were obtained during balloon-induced myocardial ischemia. ST-segment deviation was measured at the ST junction (STJ), 40&#xa0;ms (ST1), and 80&#xa0;ms (ST2) thereafter. Agreement between measured and synthesized posterior leads was assessed using Pearson correlation and Bland-Altman analyses. As an exploratory patient-level analysis, diagnostic performance was compared with reciprocal anterior ST-segment depression (V1-V4). RESULTS: Strong correlations were observed between measured and synthesized posterior lead ST-segment deviations (V7: r&#xa0;=&#xa0;0.89; V8: r&#xa0;=&#xa0;0.86; V9: r&#xa0;=&#xa0;0.83; all P&#xa0;<&#xa0;0.001). Bland-Altman analysis demonstrated minimal systematic bias (within &#xb1;0.004&#xa0;mV) and narrow limits of agreement. Synthesized posterior leads showed higher diagnostic performance than reciprocal anterior ST-segment depression (AUC 0.917 vs. 0.708), although the difference was not statistically significant (DeLong test, P&#xa0;=&#xa0;0.197). Using a 0.05&#xa0;mV threshold, synthesized posterior leads demonstrated 83.3% sensitivity, 100% specificity, and 96.2% overall accuracy. CONCLUSIONS: Synthesized posterior leads closely reproduced measured posterior lead ST-segment deviations during percutaneous coronary intervention (PCI)-induced myocardial ischemia, supporting the technical validity of posterior lead reconstruction. Larger prospective studies are warranted to determine whether synthesized posterior leads provide incremental diagnostic value beyond careful interpretation of the standard 12&#x2011;lead ECG.

Humans↗
PubMed1979

Effect of dietary supplementation of iron and ascorbic acid on lead toxicity in rats.

In our laboratory, the protective and therapeutic effects of surplus dietary iron and ascorbic acid on cadmium toxicity in rats have been studied and in this experiment, an effect of surplus iron and ascorbic acid on lead toxicity was examined. In young rats ingesting a diet containing 500 ppm of lead, growth retardation and anemia were observed. Suplementation of 400 ppm of iron and 1% of ascorbic acid to the lead containing diet prevented the growth depression and anemia and caused reductions of concentrations of lead in the kidney and tibia. Whereas, addition of 50 ppm of cadmium to the lead containing diet aggravated the growth retardation and anemia, but reduced the concentrations of lead in the kidney and tibia. Dietary supplementation of iron to the lead containing diet prevented the growth depression and anemia and reduced the accumulation of lead in the kidney, however the supplementation of ascorbic acid alone did not show any ameliolative effects. Rats were fed the lead containing diet and then transferred to the basal diet with or without iron and ascorbic acid. Recoveries from the growth retardation and anemia were not observed in rats within a week after the transfer to the non-lead diet with or without iron and ascorbic acid. These results suggest that iron prevents the growth depression and anemia in rats ingesting lead by an inhibition of lead asborption.

Animals↗
PubMed2026

Systematic multi-domain screening of lead-specific electrocardiographic features associated with sudden cardiac death.

UNLABELLED: Electrocardiogram (ECG) provides four-dimensional view to the electrical properties of the heart. We performed a comprehensive multi-domain screening to find the most significant lead-specific ECG features associated with sudden cardiac death (SCD). METHODS: We analyzed retrospective data from 21,176 consecutive patients undergoing coronary angiography in Tampere University Hospital between 2007 and 2018. 937 ECG variables provided by the 12SL algorithm were used for the analysis. From those, the significant lead-specific ECG variables were categorized into three subgroups: P-wave, QRS complex, and ST-segment/T-wave. The most significant (i.e., lowest P-value) independent lead-specific ECG variables were tested in multivariate analysis after filtering correlating variables with weaker associations with SCD. RESULTS: Among ventricular depolarization (QRS complex) variables, the strongest associations with SCD were observed for QRS intrinsicoid deflection (lead I) (p&#xa0;=&#xa0;4.6&#xa0;&#xd7;&#xa0;10-8), QRS peak-to-peak amplitude (lead aVR) (p&#xa0;=&#xa0;1.9&#xa0;&#xd7;&#xa0;10-5), and Q-wave amplitude (lead V1) (p&#xa0;=&#xa0;7.6&#xa0;&#xd7;&#xa0;10-6). Among repolarization (ST-segment and T-wave) variables, the strongest predictors of SCD were T-wave amplitude (lead aVR) (p&#xa0;=&#xa0;3.5&#xa0;&#xd7;&#xa0;10-7) and ST-segment end amplitude (lead aVL) (p&#xa0;=&#xa0;8.1&#xa0;&#xd7;&#xa0;10-5). The strongest associations with SCD among atrial depolarization (P-wave) variables were P-wave onset amplitude (lead V6) (p&#xa0;=&#xa0;3.1&#xa0;&#xd7;&#xa0;10-6), P'-wave amplitude (lead V2) (p&#xa0;=&#xa0;2.1&#xa0;&#xd7;&#xa0;10-5), and P-wave duration (lead V2) (p&#xa0;=&#xa0;2.4&#xa0;&#xd7;&#xa0;10-3). These variables remained significant in multivariate analysis alongside global ECG variables (e.g., heart rate, QRS duration, and LVH). CONCLUSION: Systematic screening and utilizing the full prognostic potential of the 12&#x2011;lead ECG reveal several key elements of the electrical properties of the heart that associate with SCD.

Humans↗
PubMed1979

Induction of myeloperoxidase deficiency in granulocytes in lead-intoxicated dogs.

Lead interferes with heme synthesis in erythrocytes and has a deleterious effect on red cell membranes. We measured myeloperoxidase (MPO) enzyme activity in the granulocytes of dogs fed increasing quantities of lead. Concurrently, iodination capability and in vitro bactericidal activity were measured. Blood lead levels were monitored. Three of 4 dogs poisoned with lead developed significant decreases in MPO enzyme activity in their granulocytes. The decline in MPO activity correlated with cumulative lead toxicity as judged by blood lead levels and clinical signs of lead poisoning. Iodination ability in all 4 dogs decreased with cumulative lead toxicity. After discontinuation of lead administration, recovery of granulocyte MPO activity preceded recovery of iodination ability. This observation suggests the possibility of separate effects of lead on iodination ability and MPO activity. Moderate impairment of bactericidal capacity developed in 3 of 4 dogs with severe lead poisoning. Clinical infections were not observed during the course of the study.

Animals↗