The use of K X-ray fluorescence for measuring lead burden in epidemiological studies: high and low lead burdens and measurement uncertainty

X-ray fluorescence (XRF), a rapid, noninvasive, low-radiation-dose method of measuring bone lead content, has emerged as a promising tool for providing an integrated estimate of low-level lead accumulation in epidemiological studies. Our group has settled on an XRF instrument that utilizes K X-rays (K-XRF) and normalizes the measurement to bone calcium. The unit of measurement provided is in micrograms of lead/gram bone mineral, an accurate proxy for micrograms of lead/gram bone ash. An estimate of measurement uncertainty is generated from the counting statistics and is theoretically dependent on several factors, primarily duration of measurement and bone mass. Data from pilot studies of community-exposed adults and workers with varying degrees of occupational lead exposure demonstrated that the K-XRF instrument can easily distinguish between populations with occupational versus environmental lead exposures. Among all subjects, bone lead increased with age. Larger measurement uncertainty was significantly associated with being female, greater subject weight, and smaller lead burdens.

Knowledge of diagnosis and reproductive history among survivors of childhood plumbism

As part of a study of the long-term consequences of childhood plumbism, 35 survivors of lead poisoning in the period 1930 through 1944 were interviewed along with 22 controls matched for age, sex, and town of residence. Subjects were asked to recall all pregnancies they engendered (men) or carried (women), outcome, and intellectual development of resulting children. Matched female plumbism subjects reported a higher proportion of spontaneous abortion or stillbirths among pregnancies (relative risk = 1.60, 95% confidence interval [CI] = 0.6-4.0) and a higher proportion of learning disabilities among school-age children (relative risk = 3.0, 95% CI = 0.9-10.2) in comparison with their controls. There was no evidence of clustering of learning disabilities within families or confounding by parental educational level. These results suggest that women with a history of childhood lead poisoning may be at risk for having spontaneous abortions or stillbirths and having children who manifest significant learning disabilities.

Measurements of pertinent concentrations of oxygen in vivo

A new method able to measure the concentration of oxygen in complex biological systems, including in vivo, has been developed using low-frequency EPR and newly characterized free radicals that are very sensitive to the concentration of oxygen. The free radicals (fusinite and lithium phthalocyanine) are very stable in tissues (for at least 150 days), apparently nontoxic, and can reflect oxygen concentrations that are less than the Km of cytochrome oxidase (0.1 microM or lower). Their biological stability is indicated by the fact that repeated measurements with fusinite of the concentration of oxygen in skeletal muscle have been made in the same animal for more than 150 days without any change in sensitivity or signs of toxicity.

The use of K X-ray fluorescence for measuring lead burden in epidemiological studies: high and low lead burdens and measurement uncertainty

X-ray fluorescence (XRF), a rapid, noninvasive, low-radiation-dose method of measuring bone lead content, has emerged as a promising tool for providing an integrated estimate of low-level lead accumulation in epidemiological studies. Our group has settled on an XRF instrument that utilizes K X-rays (K-XRF) and normalizes the measurement to bone calcium. The unit of measurement provided is in micrograms of lead/gram bone mineral, an accurate proxy for micrograms of lead/gram bone ash. An estimate of measurement uncertainty is generated from the counting statistics and is theoretically dependent on several factors, primarily duration of measurement and bone mass. Data from pilot studies of community-exposed adults and workers with varying degrees of occupational lead exposure demonstrated that the K-XRF instrument can easily distinguish between populations with occupational versus environmental lead exposures. Among all subjects, bone lead increased with age. Larger measurement uncertainty was significantly associated with being female, greater subject weight, and smaller lead burdens.

[Studies on the mutagenicity of vesnarinone]

The mutagenicity of domestic Vesnarinone (OPC-8212) was studied by Ames test, micronucleus test of NIH mouse bone marrow and chromosome aberration assay in CHL cells. Negative results were obtained, which suggested that OPC-8212 did not induce prokaryotic cell gene mutation or chromosome damage both in vitro and in vivo.

A 50-year follow-up of childhood plumbism. Hypertension, renal function, and hemoglobin levels among survivors

A group of 192 subjects with well-documented lead poisoning in 1930 to 1942 were identified in this pilot study. Thirty-five of 72 survivors traced to a Boston area address and 22 age-, sex-, race-, and neighborhood-matched controls were recruited into a clinical study. One matched subject with plumbism had grossly abnormal renal function and an elevated blood lead level of an unclear cause. Among the remaining 21 matched pairs, the risk of hypertension was significantly higher in subjects with plumbism (relative risk, 7.0; 95% confidence interval, 1.2 to 42.3). Mean adjusted creatinine clearance rates for subjects with plumbism, however, were significantly higher than those of controls and supranormal in comparison to rates predicted for sex and age. Subjects with plumbism had significantly lower hemoglobin concentrations and hematocrit readings than the controls. Blood lead and serum creatinine levels were low for both groups. These results suggest that survivors of childhood lead poisoning have an increased risk of clinically significant hypertension developing in the setting of supranormal creatinine clearance rates.

The cytological and genetic characterisation of doubled haploid lines derived from triticale×wheat hybrids

Anther culture, when applied to hexaploid triticale×wheat hybrids, offers the opportunity to re-assort wheat D genome and rye R genome chromosomes into homozygous doubled haploid lines in a single generation. The characterisation of such lines is the first step in their utilisation in wheat improvement. Two lines, M24 and M25 from the cross of 'Beagle'×'Kedong 58', and one line, M27, from the cross 'Beagle'×'Jinghua No. 1' have been characterised using different methods including conventional cytology and chromosome banding, and by using marker systems for storage protein composition (glutenins and gliadins), isozymes (α-amylase, aminopeptidase, glutamate oxaloacetic transaminase (GOT)) and RFLP markers. The results from all approaches were consistent in proving that M24 is a whole chromosome 6R/6D substitution line, while M25 and M27 are whole chromosome 1R/1D substitution lines. The relative advantages and disadvantages of each method of identification are also discussed.

Effect of repeated occupational exposure to lead, cessation of exposure, and chelation on levels of lead in bone

A sensitive K-X-ray fluorescence (K-XRF) instrument was used to measure lead levels in the tibia and patella on a series of twelve subjects who had relatively well-documented histories of lead exposure and blood lead levels. For some subjects, K-XRF measurements were taken at multiple points in time, and before and after chelation with EDTA (ethylenediamine tetraacetic acid). Results confirm that K-XRF measured bone lead levels correspond to cumulative blood lead indices and not to current blood lead levels. Moreover, the data suggest that bone lead levels; (1) correspond to urinary lead following the EDTA mobilization test unless previous chelation has occurred; (2) rise initially after lead exposure ceases and blood lead levels decrease, probably from redistribution from soft tissue, and then fall; and (3) do not decrease with a 3- to 5-day course of therapeutic EDTA chelation. K-XRF levels in the patella were noted to decrease more rapidly than levels in the tibia after cessation of lead exposure, a finding that probably reflects the greater turnover of lead in trabecular bone than in cortical bone.

[A new serotype of Salmonella IIIb]

An enterobacterium culture, S3188, providing with Salmonella biological characteristics, except exhibiting indole positive reaction, was isolated from the intestinal content of reptile a snake. It utilized malonate, did not ferment dulcitol, it attacked lactose promptly, and ONPG positive. H antigens appeared diphasic. By cross agglutination and absorption tests, it was demonstrated that the antigenic formula of this strain is 53:1, Z13:e, n,(Z15)... It was found to be a new serotype of Salmonella IIIb.

X-ray fluorescence measurements of lead burden in subjects with low-level community lead exposure

A k-x-ray fluorescence (K-XRF) instrument that can measure in vivo bone lead at low levels was used on a population of 34 adults with no known history of excessive lead exposure. A questionnaire that gathered information relevant to occupational and environmental lead exposure was administered prior to the measurement. A 30-min measurement that produced an average estimated uncertainty of 6 mcg lead/g bone mineral was taken at the mid-tibial diaphysis for each subject. Eighteen subjects had bone lead levels below the measurement uncertainty. The remainder had bone lead levels ranging up to 21 mcg lead/g bone mineral. Bone lead levels were greater among older subjects. Among young adult subjects, bone lead levels greater than the measurement uncertainty were confined entirely to subjects who had grown up in housing that was estimated to have been build prior to 1955. Such a childhood environment is at high risk of fostering exposure to biologically absorbable lead through ingestion of lead paint-contaminated dust and lead pipe-contaminated water. We conclude that the K-XRF technique has the potential to distinguish between low levels of lead burden in epidemiologic studies.

Hemoglobin Birmingham and hemoglobin Galicia: two unstable beta chain variants characterized by small deletions and insertions

Two unstable hemoglobins (Hbs) causing rather severe hemolytic anemia have been characterized. The beta chain of Hb Birmingham, found in an adult black man, is characterized by the loss of -Leu-Ala-His-Lys- at positions 141, 142, 143, and 144 and their replacement by one Gln residue. These changes are the result of a deletion of nine nucleotides, namely two base pairs (bp) of codon 141, all of codons 142 and 143, and one bp of codon 144; the remaining CAG triplet (C from codon 141 and AG from codon 144) codes for the inserted glutamine. In the beta chain of Hb Galicia from a Spanish patient, His and Val at positions 97 and 98 are replaced by one Leu residue. This is due to an ACG deletion in codons 97 and 98, which causes the removal of one His and one Val residue, while the remaining CTG triplet (C from codon 97 and TG from codon 98) codes for the inserted leucine residue. Two mechanisms, namely slipped mispairing in the presence of short repeats, and misreading by DNA polymerase due to a local distortion of the DNA helix, are considered in explaining the origin of the small deletions.

Molecular characterization of beta-thalassaemia in 174 Greek patients with thalassaemia major

The mutations producing beta-thalassaemia in 174 Greek patients with thalassaemia major were investigated by dot-blot hybridization of oligonucleotide probes to genomic DNA amplified by the polymerase chain reaction procedure, by direct sequencing of amplified DNA, and by gene mapping. beta-thalassaemia in Greeks was found to be very heterogeneous at the molecular level as 17 different mutations were observed: 86.6% of the beta-thalassaemic genes, however, could be identified with five probes: IVS-I-110 (G----A) (42.5%), codon 39 (C----T) (17%), IVS-I-1 (G----A) (13.2%), IVS-I-6 (T----C) (7.2%) and IVS-II-745 (C----G) (6.9%). Several mutations which had not previously been reported in the Greek population and which occurred at an incidence of 2% or lower were observed in this study. The information obtained will facilitate the prenatal diagnosis of beta-thalassaemia in Greece.

Effects of ultraviolet radiation

Ultraviolet radiation from high-intensity sources has well-known acute effects on the eye and skin, consisting primarily of photokeratoconjunctivitis and sunburn, which are enhanced in the presence of photosensitizing agents. Long-term elevated exposure to low-level ultraviolet radiation is also responsible for an increased risk of squamous- and basal-cell carcinomas; probably responsible for an increased risk of cortical and posterior subcapsular cataracts, pterygium, and cutaneous melanoma and intraocular melanoma and possibly responsible for immunologic effects of clinical significance.

Tear gas--harassing agent or toxic chemical weapon?

Tear gas has gained widespread acceptance as a means of controlling civilian crowds and subduing barricaded criminals. The most widely used forms of tear gas have been o-chlorobenzylidenemalononitrile and omega-chloroacetophenone. Proponents of their use claim that, if used correctly, the noxious effects of exposure are transient and of no long-term consequences. The use of tear gas in recent situations of civil unrest, however, demonstrates that exposure to the weapon is difficult to control and indiscriminate, and the weapon is often not used correctly. Severe traumatic injury from exploding tear gas bombs as well as lethal toxic injury have been documented. Moreover, available toxicological data are deficient as to the potential of tear gas agents to cause long-term pulmonary, carcinogenic, and reproductive effects. Published and recent unpublished in vitro tests have shown o-chlorobenzylidenemalononitrile to be both clastogenic and mutagenic. Sadly, the nature of its use renders analytic epidemiologic investigation of exposed persons difficult. In 1969, eighty countries voted to include tear gas agents among chemical weapons banned under the Geneva Protocol. There is an ongoing need for investigation into the full toxicological potential of tear gas chemicals and renewed debate on whether their use can be condoned under any circumstances.

The use of chemical weapons. Conducting an investigation using survey epidemiology

The use of chemical weapons in conflict represents a breach of international law as well as a grave violation of human rights. Investigating allegations of their use often is difficult. A basic tool is the survey interview. Experience has shown that a rigorous epidemiologic approach should be taken. A primary emphasis should be designing the study so that consistency of responses can be analyzed to judge the validity of the testimony. Only when the testimony can withstand this scrutiny is it possible to surmise the possible identity of agents employed. Securing samples of the putative agent is of obvious importance. Two recent investigations are discussed herein, one conducted by US Army medical researchers on allegations of chemical weapons use against the Hmong in Laos and another mounted by us on allegations of poison-gas attack against the Iraqi Kurds.

Recombination of R-D chromosome in pollen plants cultured from hybrid of 6x Triticale x common wheat

Ninety-three pollen plants derived from the hybrid F1 of 6x Triticale x common wheat were observed cytologically. The rye chromosomes presented in these plants were identified by Giemsa-banding. Pollen plants having chromosome constitution 2n = 24 in haploids and 2n=46 in diploids were found to be predominant. The chromosome distributions of the R and D genome are different. R chromosomes distributed randomly and tended to full combination in offspring, but D chromosomes distributed non-randomly and tended to maintain intact.