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 Published and recent unpublished in vitro tests have shown o-chlorobenzylidenemalononitrile to be both clastogenic and mutagenic.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.

Quantitation of hemoglobins Bart's, H, Portland-I, Portland-II and constant spring by anion-exchange high-performance liquid chromatography

We introduce a new high-performance liquid chromatographic procedure that uses a specific anion-exchange column for the separation of hemoglobin (Hb) Bart's (gamma 4), Hb H (beta 4), Hb Portland-I (zeta 2 gamma 2), Hb Portland-II (zeta 2 beta 2), and the abnormal Hb Constant Spring (alpha 2 extended beta 2) in cord blood and adult red cell lysates. The method provides quantitative data for Hb Bart's in cord blood that correlate well with the alpha-globin gene status of the babies and can be used for an initial identification of alpha-thalassemic conditions. Quantitation of Hb Bart's from cord blood samples that are collected on filter paper and submitted as dried blood spots is unreliable. The separation of Hb H and Hb Bart's allows an evaluation of the synthesis of these two hemoglobin components in patients with Hb H disease.

Beta-thalassemia intermedia in two Turkish families is caused by the interaction of Hb Knossos [beta 27(B9)Ala----Ser] and of Hb City of Hope [beta 69(E13)Gly----ser] with beta (0)-thalassemia

We have studied a few members of two Turkish families, who had a beta-thalassemia of the intermediate type. An abnormal hemoglobin was found in both families, which when present in association with beta(0)-thalassemia was considered to be the primary cause for the increased severity of the disease. In the first family this variant was Hb Knossos [beta 27(B9)Ala----Ser] which occurred together with the frameshift in codon #8 type of beta(0)-thalassemia. This compound heterozygosity, observed for the first time in the Turkish population was characterized by a considerable increase in Hb F production, mainly of the G gamma type, as expected for a chromosome with haplotype IV. In the second family, the variant was Hb City of Hope [beta 69(E13)Gly----Ser] which was present in combination with an unknown type of beta-thalassemia. The increase in Hb F production in the compound heterozygote was minimal. Reversed phase high performance liquid chromatography and the DNA amplification-synthetic oligonucleotide probe procedure were major tools in identifying the different abnormalities.

Tumor promoting activities of ethylphenylacetylurea and diethylacetylurea, the ring hydrolysis products of barbiturate tumor promoters phenobarbital and barbital, in rat liver and kidney initiated by N-nitrosodiethylamine

The ring hydrolysis products of the multi-tissue tumor promoting barbiturates, phenobarbital (PB) and barbital (BB), were fed to F344/NCr male rats previously given a single initiating injection of N-nitrosodiethylamine. Ethylphenylacetylurea (EPAU) and diethylacetylurea (EEAU), derived, respectively, from PB and BB, both promoted development of hepatocellular adenomas, but were much weaker in this respect than PB. Both acetylureas were also selective inducers of P-450IIB1-mediated benzyloxyresorufin O-dealkylase activity, but both were much less potent inducers than PB. Neither EPAU nor EEAU had an effect on tumor development in the thyroid, unlike both PB and, as shown previously, BB. EEAU, but not EPAU, strongly promoted development of renal cortical epithelial tumors. The opening of the barbiturate heterocyclic ring and the subsequent decarboxylation to yield the dialkylacetylurea analogs thus resulted in compounds displaying a marked reduction in liver tumor promoting activity. EEAU appears to possess an ability to promote renal neoplasms similar to that of its parent compound, BB. Ring opening appears to be accompanied by loss of promoting activity for thyroid follicular epithelium.

Hb natal or alpha 2(minus Tyr-Arg) beta 2: a high oxygen affinity alpha chain variant with a deleted carboxy-terminus resulting from a TAC----TAA (Tyr----terminating codon) mutation in codon alpha 140

The discovery is reported of a fast-moving alpha chain variant (Hb Natal) which is characterized by a shortened alpha polypeptide chain because of the deletion of the Tyr-Arg carboxy-terminal residues. Through amplification of appropriate segments of DNA and hybridization with synthetic oligonucleotide probes, it was possible to detect a C----A mutation in codon 140 of the alpha 2 globin gene, which causes a change in the codon for tyrosine to a terminating codon. Hb Natal or alpha 2 (minus Tyr-Arg) beta 2 has a high affinity for oxygen without a Bohr effect and heme-heme interaction. These results provide direct evidence for the importance of the tyrosine residue at alpha 140 in the oxygenation-deoxygenation process.

Inclusion body beta-thalassemia trait in a Swiss family is caused by an abnormal hemoglobin (Geneva) with an altered and extended beta chain carboxy-terminus due to a modification in codon beta 114

We have analyzed the sequence of the beta globin gene of a chromosome that is linked to the occurrence of an inclusion body beta-thalassemia characterized in the heterozygote by moderate anemia, severe red cell abnormalities, splenomegaly, inclusion body formation, elevated Hb A2 levels, and an increased in vitro alpha/beta chain synthetic ratio. The data indicate a change in codon 114 from CTG (Leu) to -GG that resulted in a frameshift and the presumed synthesis of an abnormal beta chain that is 156 residues long with a completely different C-terminal amino acid sequence. The change in codon 114 gives a -GGGCCC- sequence that creates a new ApaI site; the resulting 2.6-kilobase fragment has been observed in all subjects with this thalassemia condition. Protein structural analyses failed to demonstrate any trace of the abnormal beta chain, even in reticulocytes and nucleated red cells that were isolated by density gradient centrifugation. The inclusion bodies appear to contain mainly normal alpha chains. It is assumed that the structure of the beta-Geneva chain prevents it from combining with normal alpha chains; this results in a rapid breakdown of the abnormal protein during the early stages of red cell maturation and an accumulation of free alpha chains.

Distribution pattern of cell bodies and fibers with neurotensin-like immunoreactivity in the cat hypothalamus

Neurotensin is widely distributed in the central and peripheral nervous systems. Extensive radioimmunoassay and immunohistochemical studies in rats show that the neurotensin immunoreactive perikarya and fibers are most prominent in the hypothalamus. Radioimmunoassay studies have suggested that the levels of neurotensin in the hypothalamus of cats may be six times higher than that of rats. We studied the distribution pattern of neurotensin immunoreactivity within the hypothalamus of the cat by avidin-biotin modification immunohistochemical methods: (1) to define its distribution pattern within the hypothalamus, and (2) to compare our findings with the patterns that have been described in rats. Results show that neurotensin immunoreactive cell bodies and fibers are most prominent in the rostral and intermediate regions of the cat hypothalamus. Cell bodies with neurotensin-like immunoreactivity are seen maximally in the medial preoptic region, the infundibular nucleus, and the lateral hypothalamus. The neurotensin positive fibers are dense in the periventricular regions of the entire rostro-caudal extent of the hypothalamus. This pattern of distribution of neurotensin immunoreactivity is similar to that described in rats. The suprachiasmatic nuclei of the cat hypothalamus, however, contained a significant number of neurotensin immunoreactive cell bodies, an observation not noted in the rat hypothalamus. The neurotensin immunoreactive neurons were more numerous in the lateral hypothalamus than has been reported in rats, but the paraventricular nucleus of the hypothalamus in cats contained fewer neurotensin immunoreactive perikarya. The presence of neurotensin immunoreactive perikarya in the suprachiasmatic nucleus and the apparent increase in the number of neurotensin immunoreactive neurons in the lateral hypothalamus may account for the increased levels of neurotensin reported in cats. Neurotensin has been speculated to play a role in nociception, thermoregulation, and control of arterial pressure by acting as a hormone or a neurotransmitter. Details of the pattern of colocalization of neurotensin with that of other neuropeptides and neurotransmitters will aid in our understanding of its role in these functions.

P-450 enzyme induction by 5-ethyl-5-phenylhydantoin and 5,5-diethylhydantoin, analogues of barbiturate tumor promoters phenobarbital and barbital, and promotion of liver and thyroid carcinogenesis initiated by N-nitrosodiethylamine in rats

Male F344/NCr rats, 6 wk old, were fed 500 ppm of phenobarbital (PB) or equimolar doses of either 5-ethyl-5-phenylhydantoin (EPH) or 5,5-diethylhydantoin (EEH) in diet for 2 wk and hepatic cytochrome P-450-mediated alkoxyresorufin O-dealkylase and aminopyrine N-demethylase activities were determined. Both PB and EPH greatly increased P-450-mediated enzyme activities in rat liver while EEH was ineffective. To evaluate the hydantoins as tumor promoters, 5-wk-old male F344 rats were given a single i.p. injection of 75 mg N-nitrosodiethylamine/kg body weight. Beginning 2 wk later, they were placed either on normal diet or diet containing 500 ppm of PB or equimolar doses of EPH or EEH for the remaining experimental period. Control groups received an i.p. injection of saline followed by each of the test diets. Animals were sacrificed at either 52 or 78 wk. PB and EPH significantly enhanced the development of hepatocellular foci and hepatocellular adenomas at 52 wk and hepatocellular carcinomas at 78 wk in N-nitrosodiethylamine-initiated rats. Neither the incidence of hepatocellular neoplasms nor the number and size of hepatocellular foci was significantly increased by EEH. At 78 wk, both PB and EPH enhanced the development of thyroid follicular cell neoplasms in N-nitrosodiethylamine-initiated rats while no such enhancement was observed with EEH. Thus, EPH, a long-acting sedative/anticonvulsant, like the structurally similar PB, promoted hepatocellular and thyroid follicular cell carcinogenesis and induced the PB-inducible form(s) of cytochrome P-450 (P-450b) in rats. In contrast, EEH unlike barbital failed to promote hepatocellular and thyroid follicular cell carcinogenesis and also failed to induce PB-inducible form(s) of cytochrome P-450 in rats.

Some rare hemoglobin variants with altered oxygen affinities; Hb linkoping [beta 36(C2)Pro----Thr], Hb Caribbean [beta 91(F7)Leu----Arg], and Hb Sunnybrook [beta 36(C2)Pro----Arg]

A few rare hemoglobin variants with altered functional properties have been observed in Canadian subjects with either an erythrocytosis or mild anemia. These variants were Hb Alberta [beta 101(G3)Glu----Gly], Hb Linkoping [beta 36(C2)Pro----Thr], a new variant Hb Sunnybrook [beta 36(C2)Pro----Arg], and Hb Caribbean [beta 91(F7)Leu----Arg]. Short clinical descriptions of the subjects are given, the characterization of the variants is described in detail (except for Hb Alberta), while data from some functional analyses are provided. Comparisons with previously published data have been made and the unusual chromatographic property of two abnormal beta chains in a reversed phase high performance liquid chromatographic system is reviewed.

Hb Las Palmas or alpha 2 beta 2(49)(CD8)Ser----Phe, a mildly unstable hemoglobin variant

A new hemoglobin variant with a Ser----Phe substitution at position beta 49(CD8) was discovered in two members of a family living in the Canary Islands, Spain. Detection was by polyacrylamide gel electrophoresis and by reversed phase high performance liquid chromatography. The variant, which constituted 43% and 45%, respectively, in the two heterozygotes, was slightly unstable. Its presence did not affect hematological values though there was a mild reticulocytosis.

Hb Duan [alpha 75(EF4)Asp----Ala], Hb Westmead [alpha 122(H5)His----Gln], and alpha-thalassemia-2 (-4.2 Kb deletion) in a Chinese family

Detailed data are presented concerning the relative amounts of Hb A and two alpha chain variants (Hb Duan with alpha 75 Asp----Ala, and Hb Westmead with alpha 122 His----Gln), and the occurrence of an alpha-thalassemia-2 heterozygosity in five members of a small Chinese family. The three children who have the three abnormalities inherited the alpha-Duan and alpha-thalassemia-2 heterozygosities from their father, and the alpha-Westmead heterozygosity from their mother. The base substitution which leads to the synthesis of the alpha-Duan chain occurred at codon 75 of the alpha 1 globin gene of the chromosome which also carried the alpha-thalassemia-2 deletion; the concentration of alpha-Duan (37% of total alpha) is similar to that observed for other alpha chain variants, linked to an alpha-thalassemia-2 condition.

Convolutional reconstruction algorithm for fan beam concave and convex circular detectors

A modified convolution-backprojection reconstruction algorithm for a circular detector with an arbitrary radius of curvature has been derived for fan-beam geometries. The algorithm reduces to conventional fan-beam algorithms for flat detectors and for curved detectors having whose radii of curvature coincident with the X-ray tube focal spot. The algorithm substitutes a power series of convolution integrals in place of a single convolution integral. Computer simulations have verified the validity of the algorithm for a detector that curves away from the X-ray source. In this case, it has been demonstrated that good reconstructions are obtained when only a few of the terms of the power series are retained. The development of this algorithm represents a first step toward a cone-beam reconstruction algorithm that eventually will be used for an image-intensifier-based computerized-tomography volume imager being developed in the authors' laboratory.