Differences in weight gain in relation to race, gender, age and education in young adults: the CARDIA Study. Coronary Artery Risk Development in Young Adults

Copper/zinc (Cu/ZnSOD) and manganese (MnSOD) superoxide dismutases which catalyze the dismutation of toxic superoxide anion, O(2-)-, to O2 and H2O2, play a major role in protecting cells from toxicity of oxidative stress. However, cells overexpressing either form of the enzyme show signs of toxicity, suggesting that too much SOD may be injurious to the cell. To elucidate the possible mechanism of this cytotoxicity, the effect of SOD on DNA and RNA strand scission was studied. High purity preparations of Cu/ZnSOD and MnSOD were tested in an in vitro assay in which DNA cleavage was measured by conversion of phage phi X174 supercoiled double-stranded DNA to open circular and linear forms. Both types of SOD were able to induce DNA strand scission generating single- and double-strand breaks in a process that required oxygen and the presence of fully active enzyme. The DNA strand scission could be prevented by specific anti-SOD antibodies added directly or used for immunodepletion of SOD. Requirement for oxygen and the effect of Fe(II) and Fe(III) ions suggest that cleavage of DNA may be in part mediated by hydroxyl radicals formed in Fenton-type reactions where enzyme-bound transition metals serve as a catalyst by first being reduced by superoxide and then oxidized by H2O2. Another mechanism was probably operative in this system, since in the presence of magnesium DNA cleavage by SOD was oxygen independent and not affected by sodium cyanide. It is postulated that SOD, by having a similar structure to the active center of zinc-containing nucleases, is capable of exhibiting non-specific nuclease activity causing hydrolysis of the phosphodiester bonds of DNA and RNA. Both types of SOD were shown to effectively cleave RNA. These findings may help explain the origin of pathology of certain hereditary diseases genetically linked to Cu/ZnSOD gene.     

Ion transporters and receptors in cDNA libraries from lens and cornea epithelia

PURPOSE: To construct tissue-specific cDNA libraries containing copies of genes of ion transporting and receptor proteins in lens and cornea epithelia. To screen the libraries for the cDNA of these molecules and to deduce the protein sequence from the cDNA sequence. METHOD: Lens and corneal cDNA libraries are not commercially available and are difficult to prepare from microdissected single animal eyes or cadaver human eyes due to the small amount of tissue. To overcome these problems, we refined an approach for preparing high efficiency, non-PCR amplified plasmid cDNA libraries, where only nanogram quantities of poly (A) RNA are required. Plasmids were electrotransformed into DH10B bacteria and routinely yielded >10(6) independent colonies with typically >90% recombinants. Randomly selected colonies were subjected to colony PCR analysis to determine the libraries average insert size (typically approximately 1-kb). Primers to known genes were used in PCR amplification to check for representation of the genes in the cDNA libraries. RESULTS: Using libraries from rabbit cornea epithelium and endothelium, cultured human lens epithelium, and alphaTN4 cells, we have found the libraries to contain the cDNA for 3 common housekeeping proteins expected to be at high copy numbers in all cells. In addition, we identified 22 rare proteins and for many we determined the complete coding regions. These include K+ channels, Cl- channels, Ca++ channels, Na+ channels, three exchangers, the Na+-HCO3- cotransporter, and three kinds of receptors. CONCLUSION: Cornea and lens libraries have been constructed from single cornea or lens preparations. The libraries often contain the cDNA sequences for ion transporting and receptor proteins which are expected to be relatively rare in these cells. Many of these cDNA's have now been sequenced and the encoded proteins identified.     

Memory for emotional trait adjectives in clinically depressed youth

An experiment was conducted to examine memory for emotional trait adjectives in depressed children and adolescents. Two groups of children and adolescents, clinically depressed participants and non-clinical controls, were compared on computerized versions of recall and recognition memory tasks. Three groups of words (positive trait adjectives, negative trait adjectives, and categorized neutral words) were used in the experiment. Results showed that the depressed group recalled significantly more negative adjectives than positive adjectives, whereas the control group recalled the same number of positive and negative adjectives. This effect was predicted by the association between age and level of depression, with the depression-related bias becoming stronger with age. Signal detection analysis revealed that the depressed group did not show any bias in the recognition task. The findings are discussed with respect to cognitive theories of depression with consideration of the developmental implications.     

Angiographically defined primary angiitis of the CNS: is it really benign?

Children with B-progenitor cell acute lymphoblastic leukemia whose lymphoblasts at diagnosis accumulate high levels of methotrexate (MTX) and MTX polyglutamates (MTXPGs) appear to have a good prognosis. This has been attributed to increased sensitivity of their blast cells to MTX. However, the proportion of children who are cured of B-progenitor cell acute lymphoblastic leukemia exceeds the number whose lymphoblasts accumulate high MTXPG levels. We report that lymphoblasts from patients with < 50 chromosomes who have translocations that involve the short arm of chromosome 12 accumulate low levels of MTXPGs. These patients appear to have an excellent survival because none of 14 patients with translocations affecting 12p has relapsed, 26-79 months following diagnosis.     

Uptake of suramin by human microvascular endothelial cells

BACKGROUND: There are many causes of ulcer of the lower limb. In the elderly, venous ulcers and arteriosclerosis often coexist; for this reason pressure bandages might be contraindicated for the risk of precipitating a potentially critical arterial flow. In this work, the conditions which allow a safely treatment with pressure bandage in the elderly are evaluated. MATERIAL AND METHOD: Eleven self-sufficient elderly, with venous ulcerations to one leg only, and ankle pressure/omeral pressure between 0.92 and 0.86 were treated with elastic bandaging of the leg. RESULTS: All patients completed the treatment, with healing of the ulcer obtained in 3-8 months time. So far none of them relapsed. CONCLUSIONS: In the elderly, in selected cases, when Pc/Po > 0.86, pressure bandages can be safely applied to heal the ulcer, without running the risk of endangering arterial circulation.     

Identification of functional exonic splicing enhancer motifs recognized by individual SR proteins

Using an in vitro randomization and functional selection procedure, we have identified three novel classes of exonic splicing enhancers (ESEs) recognized by human SF2/ASF, SRp40, and SRp55, respectively. These ESEs are functional in splicing and are highly specific. For SF2/ASF and SRp55, in most cases, only the cognate SR protein can efficiently recognize an ESE and activate splicing. In contrast, the SRp40-selected ESEs can function with either SRp40 or SRp55, but not with SF2/ASF. UV cross-linking/competition and immunoprecipitation experiments showed that SR proteins recognize their cognate ESEs in nuclear extract by direct and specific binding. A motif search algorithm was used to derive consensus sequences for ESEs recognized by these SR proteins. Each SR protein yielded a distinct 5- to 7-nucleotide degenerate consensus. These three consensus sequences occur at higher frequencies in exons than in introns and may thus help define exon-intron boundaries. They occur in clusters within regions corresponding to naturally occurring, mapped ESEs. We conclude that a remarkably diverse set of sequences can function as ESEs. The degeneracy of these motifs is consistent with the fact that exonic enhancers evolved within extremely diverse protein coding sequences and are recognized by a small number of SR proteins that bind RNA with limited sequence specificity.     

Oscillatory-sensitization model of repeated drug exposure: cocaine's effects on shock-induced hypoalgesia

1. The authors have recently proposed that the sensitization produced by repeated exposure to drugs or stress may give way to an alternating pattern of increases and decreases in the response to each subsequent exposure (i.e., oscillate), as the limits of the physiological system are approached. 2. Evidence for oscillation has been obtained for 6 drug/non-drug stressors and 9 neurochemical or endocrine endpoints. This paper extends the model to a behavioral outcome. 3. In the first experiment, rats were given 0, 1, 2 or 3 pretreatments with cocaine hydrochloride (COC; 12 mg/kg i.p.), separated by 1-week intervals, and then were tested for footshock-induced hypoalgesia (5-sec, 2-mA), as measured by withdrawal latencies from a hot-plate. 4. The second experiment replicated the first and extended the pretreatment sequence to 5 COC injections. 5. In both experiments, shock significantly increased latencies over the no-shock controls. COC enhanced shock-induced hypoalgesia and this sensitization reached its maximum after 2 COC pretreatments. Thereafter, oscillation developed such that the sensitization was attenuated by 3 as compared to 2 COC injections, enhanced by 4 injections, and reattenuated after 5 COC pretreatments. 6. These data complement other findings by demonstrating that the oscillation model extends to a stress-induced behavioral outcome.