Deaths related to the inhalation of volatile substances in Texas: 1988-1998.

Analysis of death certificates in Texas from 1988 to 1998 showed that the characteristics of 144 Texans for whom inhalants were mentioned as a contributing cause of death are different from those Texans who report use of inhalants in surveys and from persons who died from inhalant abuse in Virginia. While Texas surveys show little difference in prevalence of use between white and Hispanic adolescents or between boys and girls, Texas death data indicate inhalant use is also a problem among adult white males. The mean age of decedents was 25.6 years (SD 9.8 years), and ages ranged from 8 to 62 years. There were 92% males, 81% whites, and 17% Hispanics. Of the death certificates, 35% mentioned Freon, and 25% mentioned chlorinated hydrocarbons. Of those with the mention of Freon, 42% were students (mean age 16.4 years), and 37% were mechanics, installers, and repairers (mean age 27.4 years), occupations in which Freon can be readily available. Of the chlorinated hydrocarbon deaths, 49% were students (mean age 17.5 years), and 51% were from other occupations (mean age 27.4 years). Research on drug use and the workplace is not extensive, and the effects of inhalant intoxication can be a serious problem in the workplace. Prevention campaigns need to inform the public that inhalant abuse is not just a problem among youngsters, and intervention services for adult abusers should be provided within the context of employee assistance programs.

Methods for estimating the number of "hard-core" drug users.

This article reviews methods used to estimate the number of "hard-core" drug users. Synthetic estimation methods include the population projection method, which extrapolates from areas where prevalence is known to other areas, and the principal component method, which uses relationships observed among multiple indicators to obtain a single indicator of drug use. Small area estimations project risk estimates developed from small area surveys to larger areas, and capture-recapture methods provide reliable estimates only if the underlying assumptions are met. In making estimates, researchers should understand the limitations of the data and changes in drug use patterns. The challenge for future research is to refine each method and then to combine the strengths of each to produce the best estimates possible.

Two lectin genes differentially expressed in Dolichos biflorus differ primarily by a 116-base pair sequence in their 5' flanking regions.

Previous studies in our laboratory have shown that the Dolichos biflorus plant contains two similar lectins, a seed lectin and a stem and leaf lectin called DB58, that are present at different stages in the plant's life cycle. We have now established that each of these lectins is encoded by a separate gene by isolating these lectin genes from a library of D. biflorus nuclear DNA. Restriction mapping and nucleotide sequencing analyses show that the seed lectin and DB58 genes are located in the same transcriptional orientation within 3-kilobase pairs of one another. The lectin genes contain no introns and show greater than 90% nucleotide sequence identity in their protein coding and untranslated regions. This sequence similarity extends to both the 5' and 3' flanking regions of the genes; the major exception is that a 116-base pair segment located at position -215 to -100 from the transcription start site of the seed lectin gene is missing in the 5' flanking region of the DB58 gene. The possible significance of this segment with respect to the differential expression of these genes is discussed.

Mechanism of autooxidation for hemoglobins and myoglobins. Promotion of superoxide production by protons and anions.

Several hemoglobins and bovine myoglobin are shown to undergo autooxidation reactions promoted by anions. The reduced protein in the presence of oxygen and anion yields the anion complex of the oxidized (Met) species and a second product that is almost certainly superoxide. The second product can be detected by its reduction of cytochrome c3+ at the same rates and in the same amount as the Met species. Anions are increasingly effective as promoters in the same order as their strengths as nucleophiles, e.g. Cl- less than F- less than OCN- less than SCN- less than N3- less than CN-. Rates are directly proportional to anion concentrations. A linear dependence of rate upon [H+] is also observed and can be related to the protonation of a strongly acidic group. Globin from hemoglobin A and hemes with altered 2,4-substituents gave reconstituted hemoglobins that autooxidize at rates that decrease with the electron-withdrawing power of the substituent: acetyl greater than vinyl greater than hydrogen greater than ethyl. Changes in rate with globin structure can be interpreted in terms of steric access to the ligand binding site; the more sterically restricted is the site, the slower is the reaction. The effects of [O2] on the rate vary with the degree of saturation with O2. At high O2 levels (e.g. from saturation to the point where 5% deoxyHbA and 95% oxyHbA are present), a decrease in [O2] results in an increase in the rate of azide-promoted autooxidation. At O2 levels with from 5 to 75% deoxyHbA, the rate remains nearly constant. At still lower levels with oxyHbA less than 25%, the rate decreases as [O2] is lowered. Exposure to CO reduces the rate. The reaction mechanism for anion-induced autooxidation must provide for the stoichiometric formation of a cytochrome c3%-reducing species (presumably, superoxide), the anion acting as a nucleophile in the rate-determining step, the facilitation by protons, the sensitivity of the rate to the electronegativity of heme iron, and the varied effects of [O2] upon the rate. These findings can not be fully accommodated by mechanisms in which the Met species forms either via dissociative loss of superoxide from the oxy species followed by anion binding or via displacement of protonated dioxygen from oxyheme upon nucleophilic attack of the anion at heme iron. A consistent mechanism is the reaction of protonated deoxy species with the anion followed by the reaction of Fe2+-anion complex with O2 to give Fe3+-anion and (formula, see text). Here, the deoxy rather than oxy species is involved in Fe2+ oxidation to Fe3+; O2 can serve as one-electron acceptor but not while serving as an iron-bound ligand. A precise non-iron site for electron transfer from ferrous porphyrin to O2 remains unlocated but a process involving the porphyrin pi-system has analogy in simple heme, flavin, or other organic donor reactions with O2 that yield superoxide...

Geodynamics--where are we and what lies ahead?

The introduction and evolution of the plate tectonics hypothesis during the past two decades has sparked the current renaissance of research in the earth sciences. An outgrowth of active geophysical and geological exploration of the oceans, the plate tectonics model has come under intense scrutiny by geologists, geochemists, and geophysicists who have attempted to apply the model to the origin and growth of continents, the generation of oceanic and continental crust, and the nature of the lithosphere, asthenosphere, and underlying mantle with respect to their evolution through time and to the driving mechanism or mechanisms for plate tectonics. The study of other terrestrial planets and moons has been helpful in understanding the earth model. The unequal distribution of geological features, both in the continents and oceans, emphasizes the need for ongoing studies of international scope such as the recently completed International Geodynamics Project and its successor, the International Lithosphere Program, both stressing studies related to the dynamics of the lithosphere.

An infrared study of NO bonding to heme B and hemoglobin A. Evidence for inositol hexaphosphate induced cleavage of proximal histidine to iron bonds.

Five- and six-coordinate nitrosyl hemes have been prepared and their infrared, electron paramagnetic resonance (EPR), and visible-Soret spectra compared with the corresponding spectra for nitrosyl hemoglobin A (Hba-NO) determined both in the presence and the absence of inositol hexaphosphate (IHP). The five- and six-coordinate NO complexes prepared from either dipyridine or pyridine carbonyl protoheme dimethyl ester had N-O stretch bands (nuno) near 1675 and 1625 cm-1, respectively. These frequencies are sensitive to change in solvent (nuno decreased as the dipole moment of the solvent increased) and, with six-coordinate species, to changes in trans ligand. However, these solvent and trans ligand effects were small compared with the difference (ca. 50 cm-11) between five- and six -coordinate species. The nature of the trans ligand affected the relative proportions of the two...