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Biomedical subjects

J J Chisolm

Publications and source records attributed to J J Chisolm.

At least 19 recordsLinked to original sources
PubMed1991

An evaluation of experimental practices for abatement of residential lead-based paint: report on a pilot project.

In this pilot study, we prospectively evaluated experimental practices for abating lead-based paint in six dwellings. These experimental abatements were based upon a new approach to abatement which reflects current understanding of low-level lead toxicity in children and the role of lead-contaminated dust as an important contributor to children's total body burden. Our previous study of traditional abatement practices in Baltimore showed them to be inadequate for reducing lead in both house dust and children's blood. Our experimental abatements resulted in significant reductions in house dust-lead levels (PbD) which persisted during 6-9 months of followup. Geometric mean PbD at floors, window sills, and window wells were respectively 5.6, 49.6, and 316.7 mg/m2 at preabatement, and respectively 0.6, 4.4, and 10.8 mg/m2 at 6-9 months. Experimental abatements involved (1) treatment of lead-painted surfaces above and below 4 ft from the floor, including interior and exterior components of windows; (2) sealing or covering of wooden floors; (3) procedures for containment of dust during abatement; and (4) a final cleanup using a high-efficiency particle air (HEPA) vacuum. We recommend that more research be done to further evaluate and compare the long-term efficacy of these and other abatement methodologies.

Dust↗
PubMed1990

Evaluation of the potential role of chelation therapy in treatment of low to moderate lead exposures.

In the overall long-term management of lead poisoning, chelation therapy can have short-term benefits; however, these benefits must be accompanied by drastic reduction in environmental exposure to lead if therapy is to have any long-term benefit. This discussion is limited to calcium disodium ethylenediaminetetraacetate (CaNa2EDTA), the chelating agent that has been the mainstay of treatment of lead poisoning for the past 38 years, and to meso-2,3-dimercaptosuccinic acid (DMSA), a new and promising oral chelating agent, which is an orphan drug and is currently classified as an investigational new drug by the U.S. Food and Drug Administration. With both drugs, multiple courses of treatment will be needed if any substantial reduction in body lead burden is to be achieved. A major limitation of CaNa2EDTA is the enormous diuresis of zinc that it produces. DMSA produces a comparable diuresis of lead, a greater decrease in blood lead, and has negligible influence on the urinary losses of zinc, copper, iron, and calcium. Limited experience to date in man has revealed no significant adverse side effects of DMSA. In animals, DMSA will promptly reduce the concentration of lead in brain and kidney, in particular. By contrast, similar 5-day courses of CaNa2EDTA do not produce any net reduction in brain lead. This is important, as the brain is the critical organ of the adverse effects of lead in children. If the efficacy of DMSA is to be comprehensively evaluated ethically in children, new and more sensitive neurochemical, electrophysiologic, or other markers must be developed.

Animals↗
PubMed1990

Health and environmental outcomes of traditional and modified practices for abatement of residential lead-based paint.

We evaluated traditional and modified practices for abating lead-based paint in homes of children with blood-lead concentrations (PbB) greater than 1.4 mumol/L (greater than 29 micrograms/dl). Traditional abatement resulted in acute increases in: 1) lead contaminated house dust (generally 3 to 6-fold over pre-abatement levels, but at abated sites typically 10 to 100-fold); and 2) the PbBs of nearly half of the occupant children. Modified practices represented modest short-term improvement compared to traditional practices but were also inadequate. By six months, it was clear that neither form of abatement resulted in long-term reductions of PbB or house dust lead levels, leaving children at continued risk of excessive exposure to lead and permanent adverse neurobehavioral effects. Windows were found to be high sources of lead contaminated house dust. Recommendations are made for improved abatement practices including more complete abatement of window units and more effective clean-up to remove lead-bearing dust. Thirteen million US children live in lead-painted dwellings. Research is needed to identify abatement strategies that will be practical and well suited to the current understanding of low-level lead toxicity.

Child↗
PubMed1987

Toxic lead exposure in the urban rock dove.

Thirteen adult urban rock doves (Columba livia), 12 captured alive and one found dead, were studied from the Baltimore zoo. The mean concentration of lead in the blood for the 12 live birds was 184.5 +/- 531.2 (range 10.5-1,870 micrograms/dl). Three of the 13 birds with high measured blood and tissue lead concentrations were found at necropsy with lead shot pellets in their gizzards. Correlations were not found between concentrations of lead in the blood and body weight or hematocrit. Conversely, high correlations were noted between concentrations of lead in the blood and measured liver and kidney concentrations (r = 0.946, P less than 0.01; r = 0.993, P less than 0.01, respectively). Numbers of intranuclear acid-fast inclusions per 10 consecutive fields (100x oil immersion lens) correlated well with measured kidney lead concentrations (r = 0.990, P less than 0.001).

Animals↗
PubMed1986

Lead toxicity masquerading as sickle cell crisis.

We recently saw a 12-year-old black boy with known sickle cell disease who had been seen many times for abdominal pain thought to be secondary to a vasoocclusive crisis. The patient eventually was admitted, after a seizure and the onset of obtundation. The etiology of his acute encephalopathy remained unclear until bone films of his knees fortuitously revealed "lead lines." The patient was treated and did well subsequently. This case emphasizes the importance of considering other diagnoses when a sickle cell patient presents with a crisis.

Anemia, Sickle Cell↗
PubMed1986

Lead exposure in an "urban" peregrine falcon and its avian prey.

Necropsy of a 7-yr-resident peregrine falcon (Falco peregrinis) from Baltimore showed a Pseudomonas infection involving the pharynx as the immediate cause of death. Concentrations of lead in liver and kidney measured 0.74 and 1.40 ppm, respectively. A survey of lead exposure was performed on 40 urban rock doves (Columbia livia). Thirteen additional rock doves were collected from sites removed from lead contamination and served as controls. The mean concentration of lead in the blood of the urban rock doves was 0.96 ppm (range 0.29-17.0 ppm) compared to 0.05 ppm (0.01-0.07 ppm) for control birds. Ninety-eight percent (39/40) of the urban rock doves had elevated concentrations of lead in their blood, while 27% (11/40) had sublethal concentrations. None of the control birds had increased concentrations of lead in their blood. Concentrations of lead in liver and kidney of 13 urban rock doves were 3.48 ppm and 9.53 ppm, respectively, compared to concentrations of 0.43 ppm and 0.50 ppm for four control rock doves. From these data a mean total concentration of lead per rock dove was calculated at 4.60 ppm for urban birds and 0.33 ppm for control birds.

Animals↗
PubMed1985

The relationship between the level of lead absorption in children and the age, type, and condition of housing.

A group of 184 preschool-aged children with pretreatment blood lead concentrations (PbB) greater than or equal to 50 micrograms/dl, who received inpatient chelation therapy, were followed prospectively as outpatients for 12 months after discharge. Of these, 160 were followed for 24-30 months. Serial PbB data were analyzed according to the type of housing to which each child was discharged. Following therapy, PbB stabilized by 3 months. Thereafter, highly significant differences (P less than 0.001) existed between those living in or visiting old houses in which lead-in-paint hazards had been abated according to local ordinances (m PbB = 38.5 micrograms/dl) and those discharged to "lead-free" public housing (m PbB = 28.8 micrograms/dl) or to recently, totally gutted and renovated old housing (m PbB = 28.7 micrograms/dl). During the period of study (1978-1982), no downward trend in PbB within housing groups was found during the first 12 months of follow-up. Of the 152 children discharged to old housing, 75 had 127 recurrences of PbB greater than or equal to 50 micrograms/dl. This emphasizes the need for close and prolonged follow-up in all cases. These data indicate that substantially improved methods of detection, classification, and abatement of lead hazards must replace traditional methods if lead exposure for young children in old housing is to be reduced to an acceptable level.

Child↗
PubMed1985

Erythrocyte porphobilinogen synthase activity as an indicator of lead exposure in children.

The European standardized method for measuring porphobilinogen synthase (PBGS, EC 4.2.1.24) activity in peripheral erythrocytes is widely used in epidemiological studies of low-level Pb absorption. We have modified it to include activation with dithiothreitol (DTT). In children with concentrations of Pb in whole blood ranging from 0.29 to 1.93 mumol/L, we found the following statistically significant correlations (r): blood Pb vs nonactivated PBGS activity = -0.773 (p less than 0.005); blood Pb vs DTT-activated PBGS activity = -0.265 (p less than 0.005); blood Pb vs the ratio of DTT-activated/nonactivated PBGS activity = +0.818 (p less than 0.005). At a DTT-activated/nonactivated PBGS activity ratio of 1, which indicates no Pb-dependent inhibition of PBGS, a corresponding blood Pb concentration of 0.24 mumol/L (50 micrograms/L) would be predicted. In individuals with hematological disorders, the DTT-activated/nonactivated ratio better predicted blood concentration of Pb than did the nonactivated PBGS activity, and largely compensated for the high variability in PBGS activity. We also describe techniques to minimize contamination by Zn and Pb and to stabilize enzyme activity during collection, transport, storage, and analysis of samples.

Adolescent↗
PubMed1985

Use of 2,3-dimercaptopropane-1-sulfonate in treatment of lead poisoning in children.

2,3-Dimercaptopropane-1-sulfonate (DMPS) is a water-soluble metal complexing agent. Administration to lead-poisoned children of 5-day courses of 200 or 400 mg of DMPS per m2 surface area per day given p.o. in divided doses resulted in a significant decline in the concentration of lead in blood. DMPS treatment did not significantly alter the concentrations of zinc or copper in plasma. Urinary excretion of lead, zinc and copper was increased by DMPS administration and these increases were sustained throughout the 5-day course of treatment. No significant changes in hepatic, renal or hematological function were found in DMPS-treated children and no side effects attributable to DMPS were noted. It is concluded that a 5-day course of DMPS given p.o. may be safe and effective in the treatment of asymptomatic lead poisoning in children.

Aspartate Aminotransferases↗
PubMed1977

Is lead poisoning still a problem?

Today, health professionals are concerned about whether asymptomatic or mildly symptomatic increases in lead absorption in preschool children is one of the important factors causing minimal brain dysfunction, which only becomes evident later during the school years. This concern arises, in part, because current screening data show that 5 to 10% of the children tested recently in the United States have a degree of increase in lead absorption sufficient to cause metabolic derangement in heme synthesis, but insufficient, with rare exception, to cause classical acute clinical symptoms of plumbism. These screening data are disturbing because similar increases in lead absorption in suckling (but not older) experimental animals have been shown in some studies to be followed by the delayed appearance of subtle deficits in learning ability and aberrations in behavior. Derangement of hemoglobin synthesis is the first adverse effect of increased lead absorption now detectable. Intervention on the basis of the first or critical effect of a toxic agent before more serious effects occur has advantages from the viewpoint of preventive medicine. Current CDC guidelines for prevention of childhood lead poisoning are based on this concept and recommend the use of micro-scale erythrocyte protoporphyrin tests in conjunction with micro blood lead tests for early detection of children with disturbed heme synthesis caused by lead.

Aminolevulinic Acid↗