Contrast media algogenic potential in peripheral arteriography. Potentiation of bradykinin-induced pain in the rat

RATIONALE AND OBJECTIVES

Contrast media (CM) with minimal algogenic (pain causing) potential in animal models of peripheral arteriography are still able to produce vascular pain in humans; the poor predictive value of preclinical evaluation led us to develop a more sensitive method based on CM potentiation of bradykinin effects in the rat.

METHODS

Behavioral pain responses and histologic alterations of the arteries were determined after intrafemoral injection of bradykinin to saline- or CM-pretreated rats. Pain reactions were compared with those elicited by single and repeated CM injections.

RESULTS

Contrast media enhanced bradykinin-induced pain was dose dependent with the following potency order: iopamidol > iopromide > ZK 139129 > ZK 119095. Vasodilation and alterations of the arterial internal layer also were seen. Iopromide produced this sensitization at doses that did not elicit evident pain reactions per se.

CONCLUSION

The method proved to be a highly sensitive preclinical discriminant of CM algogenic potential.

A novel use of differential equations to fit exponential functions to experimental data

A procedure for fitting multi-exponential functions to experimental data is described. It is fast, requires no initial parameter estimates and is particularly suited to sums of several closely spaced exponentials. The method comprises the application of three well tried numerical techniques: (i) the signal is smoothed by representing it as an abbreviated Legendre series; (ii) the coefficients of a certain kind of differential equation are determined such that it's solution is the closest fit to the smoothed signal; and (iii) the amplitudes of the exponential components are determined, given the calculated values of the exponential rate constants. The method is computationally efficient, since determination of amplitudes and exponents involves the use of linear techniques, and therefore does not require multiple iterations, and the smoothed signal is contained in a handful of coefficients rather than as a lengthy time series. The severe ill-conditioning that is unavoidable in this problem is contained within the well-understood procedures of inverting a matrix and determining the roots of a polynomial. This method is particularly appropriate for analysis of data that may be modelled by a scheme of linked first-order reactions, describing for example the stochastic behaviour of ion channels, a chemical reaction, or the uptake and distribution of a drug within body compartments.

Insulin-like growth factor binding proteins: a review of methodological aspects of their purification, analysis and regulation

The reason why there are at least 6 distinct high affinity IGFBPs is obviously a great challenge for investigators to unravel. In order to undertake this challenge a wide range of techniques have now been developed for investigating IGFBPs. As the IGFBPs have been characterized it has become clear that they are complex multi-faceted molecules; the more tools that can be applied to examine them, the better are the chances for getting a complete picture. The return for the investment of all this technology is the hope that elucidation of the sophisticated system of IGFBPs will provide a much better understanding of how the pluripotential actions of the ubiquitous IGFs can be most appropriately regulated in a manner specific to each tissue and according to developmental and environmental conditions.

Factors affecting caries experience in French adolescents

Three hundred French 14-15-yr-old adolescents were randomly selected. They were examined clinically and caries experience was determined by using the DMFS index. The aim of this investigation was to evaluate children's habits using a self-administered questionnaire, to clarify the actual influence of well-known factors such as fluoride exposure, diet, oral hygiene and socioeconomic factors on caries experience and to stress those factors of primary importance. A multiple regression analysis revealed the variables which significantly contributed to explain DMFS scores in a final model: Age, sex, frequency of sweet consumption, use of standard or high fluoride toothpastes, bleeding during toothbrushing, living in St Yorre (F- = 0.45 mg/l). At a time when caries experience is decreasing, it seems that fluoride supply, snacking and oral hygiene are still independent and significant determinants of caries experience in French adolescents.

Childhood sexual abuse and mental health in adult life

The relationship between childhood sexual abuse and mental health in adult life was investigated in a random community sample of women. There was a positive correlation between reporting abuse and greater levels of psychopathology on a range of measures. Substance abuse and suicidal behaviour were also more commonly reported by the abused group. Childhood sexual abuse was more frequent in women from disrupted homes as well as in those who had been exposed to inadequate parenting or physical abuse. While elements in the individual's childhood which increased the risks of sexual abuse were also directly associated to higher rates of adult psychopathology, abuse emerged from logistic regression as a direct contributor to adult psychopathology. Severity of abuse reported was related to the degree of adult psychopathology. The overlap between the possible effects of sexual abuse and the effects of the matrix of disadvantage from which it so often emerges were, however, so considerable as to raise doubts about how often, in practice, it operates as an independent causal element. Further, many of those reporting childhood sexual abuse did not show a measurable long-term impairment of their mental health. Abuse correlated with an increased risk for a range of mental health problems, but in most cases its effects could only be understood in relationship to the context from which it emerged.

Association of anti-58 kDa endoplasmic reticulum antibodies with halothane hepatitis

We recently showed that when rats were administered the inhalation anesthetic halothane, a 58 kDa liver endoplasmic reticulum protein became covalently trifluoroacetylated by the trifluoroacetyl chloride metabolite of halothane. Although the 58 kDa protein showed 99% identity to that of the deduced amino acid sequence of a cDNA reported to correspond to phosphatidylinositol-specific phospholipase C-alpha, it did not have phosphatidylinositol-specific phospholipase C activity. It was concluded that the reported cDNA of phosphatidylinositol-specific phospholipase C-alpha actually encoded for the 58 kDa endoplasmic reticulum protein of unknown function. Other researchers have come to the same conclusion and have shown that the 58 kDa protein has protein disulfide-isomerase and protease activities. We now report that patients with halothane hepatitis have serum antibodies that react with both purified trifluoroacetylated and native rat liver 58 kDa proteins. These results suggest that when patients are exposed to halothane a human liver orthologue of the rat liver trifluoroacetylated-58 kDa protein is formed. In certain patients, this protein may become immunogenic and lead to the formation of specific antibodies and or specific T-cells, which may react with both trifluoroacetylated and native 58 kDa proteins, and ultimately be responsible, at least in part, for the hepatitis caused by halothane.

Halothane hepatitis patients have serum antibodies that react with protein disulfide isomerase

Clinical and laboratory evidence suggests that the fulminant liver failure sometimes associated with the inhalation anesthetic halothane may be an immune-mediated toxicity. Most importantly, the vast majority of patients with a clinical diagnosis of halothane hepatitis have serum antibodies, which react with one or more specific liver microsomal proteins that have been covalently altered by the trifluoroacetyl chloride metabolite of halothane. The serum antibodies are specific to halothane hepatitis patients and are not seen in sera of patients with other types of liver pathology. In this study, a 57-kD trifluoroacetylated liver microsomal neoantigen associated with halothane hepatitis and native 57-kD protein were purified from liver microsomes of halothane-treated and -untreated rats, respectively. When the purified trifluoroacetylated 57-kD and native 57-kD proteins were used as test antigens in an enzyme-linked immunosorbent assay, serum antibodies from halothane hepatitis patients (n = 40) reacted with both of these proteins to a significantly greater extent than did serum antibodies from control patients (n = 32). On the basis of its apparent monomeric molecular mass, isoelectric point and NH2-terminal amino acid and tryptic peptide sequences, the 57-kD protein has been identified as rat liver protein disulfide isomerase. Antibodies raised against rat liver protein disulfide isomerase also reacted with a protein of approximately 58-kD in human liver microsomes. The results of this investigation suggest that trifluoroacetylated protein disulfide isomerase is one of the immunogens associated with halothane hepatitis. In certain patients it might lead either to specific antibodies or, possibly, to specific T cells, which could be responsible for halothane hepatitis.

Estimated condom failure and frequency of condom use among gay men

OBJECTIVES

Condoms are designed to bar transmission of the human immunodeficiency virus (HIV), but they sometimes fail. This paper explores the effect of experience with condoms on condom failure among gay men.

METHODS

Risk of condom failure (breakage or slippage) on a single occasion is estimated for four sexual acts reported over 12 months by a sample of gay New York City men (n = 741). The estimation procedure assumes that each episode in which a condom is used is an independent event. Evidence is offered to support this assumption.

RESULTS

Risk of condom failure in a single episode was fairly high, particularly in anal intercourse, for men who had engaged in each act only a few times in the previous year. It declined rapidly with experience (e.g., to below 1% for receptive anal intercourse after about 10 episodes in the previous year). Condoms failed less often in oral than anal sex, but estimated risk of failure also decreased with experience.

CONCLUSIONS

Gay men should be especially cautious the first few times they use a condom; after moderate experience, however, they may expect a low risk of condom failure.

Crystal structure of the DsbA protein required for disulphide bond formation in vivo

Proteins that contain disulphide bonds are often slow to fold in vitro because the oxidation and correct pairing of the cysteine residues is rate limiting. The folding of such proteins is greatly accelerated in Escherichia coli by DsbA, but the mechanism of this rate enhancement is not well understood. Here we report the crystal structure of oxidized DsbA and show that it resembles closely the ubiquitous redox protein thioredoxin, despite very low sequence similarity. An important difference, however, is the presence of another domain which forms a cap over the thioredoxin-like active site of DsbA. The redox-active disulphide bond, which is responsible for the oxidation of substrates, is thus at a domain interface and is surrounded by grooves and exposed hydrophobic side chains. These features suggest that DsbA might act by binding to partially folded polypeptide chains before oxidation of cysteine residues.

Characterization of the binding defect in insulin-like growth factor binding protein-3 from pregnancy serum

During pregnancy, insulin-like growth factor (IGF) binding protein-3 (IGFBP-3) undergoes proteolysis, rendering it undetectable by radioligand binding techniques. This study examines the physical and functional defect in pregnancy IGFBP-3. Ternary complex formation has been measured by the binding of the acid-labile subunit of the circulating IGFBP-3 complex, which also requires IGF-I or IGF-II binding. IGF-depleted pregnancy IGFBP-3, prepared by size-exclusion chromatography at low pH, could not form a ternary complex in the presence of [Tyr60]IGF-I or of an IGF-I analogue extensively altered in the A-domain, whereas analogues altered in the C- or D-domains complexed as well as native IGF-I. After purification by immunoaffinity chromatography, non-pregnancy and pregnancy IGFBP-3 formed ternary complexes with IGF-I equally well, although the pregnancy-proteolysed protein appeared degraded to approximately 30 kDa. On analysis by affinity labelling, cross-linked ternary complexes containing non-pregnancy or pregnancy IGFBP-3 were predominantly 135-140 kDa, with an additional complex of 110-115 kDa in the pregnancy preparation. After reverse-phase h.p.l.c., affinity-isolated pregnancy IGFBP-3 was inactive, whereas the protein from non-pregnancy serum retained activity. Thus pregnancy-proteolysed IGFBP-3 is altered in its specificity for IGF analogues, and is more labile than non-pregnancy IGFBP-3, but shows little impairment in normal IGF binding or ternary complex formation.

Serum antibodies from halothane hepatitis patients react with the rat endoplasmic reticulum protein ERp72

Immunoblotting studies have previously shown that serum antibodies from halothane hepatitis patients react with several liver microsomal proteins that have been modified by the trifluoroacetyl halide metabolite of halothane. In this study, an 80-kDa protein recognized by the patients' antibodies has been purified from rat liver microsomes and characterized. When the purified trifluoroacetylated 80-kDa and native 80-kDa proteins were employed as test antigens in an enzyme-linked immunosorbent assay, serum antibodies from halothane hepatitis patients reacted with both of these proteins to a significantly greater extent than did serum antibodies from control patients. Amino acid sequence analyses of several hydrolytic peptide fragments of the 80-kDa protein showed that the protein was 99% identical to the deduced amino acid sequence of a murine cDNA of the luminal endoplasmic reticulum protein ERp72. These results indicate that trifluoroacetylated ERp72 in the liver of halothane hepatitis patients may induce immune responses against epitopes present on the covalently altered protein and those present on the native protein and may have a role in halothane hepatitis. In addition, immunoblot and immunohistochemical studies revealed that the 80-kDa protein was present in all tissues studied, but was in highest concentration in liver, adipose tissue, ovaries, and testes and was enriched in specific cells of some organs. In the future, these findings should help define the physiological function of ERp72.

The 5'-triphosphates of the (-) and (+) enantiomers of cis-5-fluoro-1-[2-(hydroxymethyl)-1,3-oxathiolane-5-yl]cytosine equally inhibit human immunodeficiency virus type 1 reverse transcriptase

The (-) enantiomer of cis-5-fluoro-1-[2-(hydroxymethyl)-1,3-oxathiolane-5-yl]cytosine is a potent inhibitor of human immunodeficiency virus type 1 in vitro. The 5'-triphosphates of the (-) and (+) enantiomers equally inhibited the production of full-length minus-strand DNA in an endogenous reverse transcriptase reaction, each competitively inhibited DNA synthesis, and each was used as a chain-terminating substrate.

Crystallographic binding studies on the allosteric inhibitor glucose-6-phosphate to T state glycogen phosphorylase b

Glucose-6-phosphate is an important allosteric inhibitor of glycogen phosphorylase b that restrains the enzyme in the inactive state in resting muscle. A crystallographic binding study by diffusion of glucose-6-phosphate into performed crystals of T state phosphorylase b has been carried out at 2.3 A resolution and the structure refined by restrained crystallographic least-squares and simulated annealing to give a crystallographic R-value of 0.203. The inhibitor binds at the AMP allosteric effector site at the subunit-subunit interface of the dimer. The phosphate groups of the glucose-6-phosphate and AMP occupy partially overlapping sites and make similar contacts to two arginine residues (Arg309 and Arg310) but in glucose-6-phosphate there is a contact to a third arginine (Arg242). The glucopyranose of glucose-6-phosphate and the adenine ribose of AMP occupy different positions. Including the contacts to the three arginine residues by the phosphate group, the glucose-6-phosphate makes a total of 11 hydrogen-bonds to the enzyme and all but one of these are to charged groups. The O-2 hydroxyl hydrogen-bonds to the main-chain carbonyl oxygen of Val40' from the other subunit and this interaction appears important for the allosteric response. There are substantial conformational changes both in the vicinity of the glucose-6-phosphate (involving for example Phe196 and Arg309) and at the subunit interface (involving residues 42' to 51' and 192 to 196). These shifts tighten the binding of the inhibitor and the interface. Comparison of the glucose-6-phosphate complex with the T state native phosphorylase b and the R state phosphorylase a structures shows that there is a graded response from T state glucose-6-phosphate complex through T state phosphorylase b to R state phosphorylase a that suggests that glucose-6-phosphate promotes a tight structure that is more "tensed" than native T state phosphorylase b. The results show how the same allosteric effector site can exhibit a tight binding site for the activator AMP in the R state structure and a tight binding site for glucose-6-phosphate in the modified T state structure.

Dimensions and form of dental arches in subjects with normal occlusions

To determine the main mandibular dental arch forms, 278 dental casts of untreated French adults with normal occlusions were examined. Six measurements of the mandibular dental arches were performed, and five independent ratios were determined. By following the k-means clustering method on the basis of these ratios and the use of polynomial functions of the sixth degree, five mandibular dental arch forms were defined, and an arch guide was developed. The proposed forms are relatively narrow in comparison with previous studies. No significant differences in their distributions were seen between male and female subjects. However, the dental arches of the women have smaller dimensions.

Mechanism of resistance of human immunodeficiency virus type 1 to 2',3'-dideoxyinosine

A molecular clone containing the wild-type reverse transcriptase (RT) coding region of human immunodeficiency virus type 1 (HIV-1) was constructed, and site-directed mutagenesis was used to introduce mutations--Leu74-->Val (L74V), T215Y, and the combination L74V/T215Y--into the RT coding region. The proteins were purified by immunoaffinity chromatography. Assays were performed with mutant and wild-type RT to determine substrate and inhibitor specificity. All three mutant enzymes catalyzed the incorporation of substrate 2'-deoxynucleoside 5'-triphosphates (dNTPs) as efficiently as wild-type HIV-1 RT. Small changes were observed in the Km values for dNTPs with all three mutant enzymes, while more significant changes were noted in sensitivity to nucleoside 5'-triphosphate analogues that inhibit the enzyme activity. Results suggest that altered substrate recognition by the HIV-1 RT is involved in the mechanism of resistance.

Nonexponential relaxation after ligand dissociation from myoglobin: a molecular dynamics simulation

Molecular dynamics simulations of myoglobin after ligand photodissociation show that the out-of-plane motion of the heme iron has a rapid subpicosecond phase followed by a slower nonexponential process involving more global protein relaxation. Individual trajectories show rather different behavior, suggesting there is an inhomogeneous component to the relaxation. The calculated time dependence of the iron motion over 100 ps is in excellent agreement with the frequency shift of band III of the heme group [see Lim, M., Jackson, T. A. & Anfinrud, P. A. (1993) Proc. Natl. Acad. Sci. USA 90, 5801-5804]. If that the barrier to rebinding depends on the out-of-plane iron position, the time dependence obtained from the simulation can explain the nonexponential room-temperature geminate recombination of NO.

Arachidonic acid stimulates glucose uptake in cerebral cortical astrocytes

Arachidonic acid (AA) has recently been shown to influence various cellular functions in the central nervous system. Here we report that AA increases, in a time- and concentration-dependent manner, 2-deoxy-D-[1-3H]glucose ([3H]2DG) uptake in primary cultures of astrocytes prepared from the cerebral cortex of neonatal mice. This effect is mimicked by an unsaturated fatty acid such as linolenic acid, while palmitic and arachidic acids, two saturated fatty acids, are inactive. Pharmacological agents that increase the endogenous levels of AA by stimulating AA release (melittin) or by inhibiting its reacylation (thimerosal) also promote [3H]2DG uptake by astrocytes. We also report that norepinephrine (NE) stimulates the release of [3H]AA from membrane phospholipids, with an EC50 of 3 microM; this effect is accompanied, with a temporal delay of approximately 4 min, by the stimulation of [3H]2DG uptake, for which the EC50 of NE is 1 microM. Since the cerebral cortex, the brain region from which astrocytes used in this study were prepared, receives a massive noradrenergic innervation, originating from the locus coeruleus, the effects of NE reported here further stress the notion that certain neurotransmitters may play a role in the regulation of energy metabolism in the cerebral cortex and point at astrocytes as the likely targets of such metabolic effects.

Attitudes to reducing violence towards women: punishment or prevention?

AIM

To investigate the attitudes of abused and nonabused women to reducing physical and sexual violence in the community.

METHOD

A random community sample of 3000 women was surveyed by postal questionnaire as part of the Otago Women's Health Survey. Seventy three percent (n = 1663) of those under 65 replied. As well as demographic, mental health and abuse information, responses to the question "what steps would you like to see taken to reduce the incidence of sexual and physical harm to women and children?" were analysed.

RESULTS

Education was the most favoured approach to reducing violence in the community, followed by increased punishment of the offender. Women who had experienced sexual abuse, particularly as children, were more likely to advocate measures other than punishment. Rural women, those without formal qualifications and those who were not abused were more likely to advocate increased punishment, or made no comment.

CONCLUSION

The finding that victims of sexual assault were likely to report a preference for prevention over punishment highlights the importance of representing the views of the community which appear to be at variance with more extreme views publicized in the media.

Effects of AIDS-related bereavement and HIV-related illness on psychological distress among gay men: a 7-year longitudinal study, 1985-1991

In this study we examined the influence of acquired immunodeficiency syndrome (AIDS)-related bereavement on psychological distress from 1985 through 1991. We predicted that this relation would be influenced by personal knowledge of human immunodeficiency virus (HIV) infection and symptoms consistent with HIV-related illness. Interview data collected each year on a cohort of 746 gay men included information on the deaths and illnesses of network members caused by AIDS, as well as on psychological distress, sedative use, HIV-related symptoms, and HIV infection status. Significant main effects of bereavement were found in each year after controlling for both losses occurring from 1 to 2 years previously and for AIDS and HIV health status. The intensity and duration of these bereavement effects diminished over time. Groups of men who were both bereaved and classified as having AIDS or were HIV positive reported the highest level of distress in every year compared with the 3 other groups.

Crystallization of DsbA, an Escherichia coli protein required for disulphide bond formation in vivo

DsbA is a 21 kDa protein that facilitates disulphide bond formation and is required for the correct folding and stability of a number of exported proteins in Escherichia coli. Crystals of oxidized DsbA have been obtained from polyethylene glycol 8000 (20 to 25%), 0.1 M-cacodylate buffer (pH 6.5) and 1% 2-methyl-2,4-pentanediol. Oxidation of the protein is critical for reproducibly obtaining high quality crystals. The resulting crystals diffract to 2 A and belong to the monoclinic space group C2 with cell dimensions a = 117.5 A, b = 65.0 A, c76.3 A, beta = 126.3 degrees with two molecules in the asymmetric unit.

Biochemical analysis of human immunodeficiency virus-1 reverse transcriptase containing a mutation at position lysine 263

Site-directed mutagenesis has been used to assess the importance of lysine 263 in substrate binding of human immunodeficiency virus-1 (HIV-1) reverse transcriptase. Previous studies have indicated that lysine 263 functions in the binding of 2'-deoxynucleoside 5'-triphosphate (dNTP) substrates (Basu, A., Tirumalai, R. S., and Modak, M. J. (1989) J. Biol. Chem. 264, 8746-8752). We studied this interaction directly by using site-specific mutagenesis to change lysine 263 to a serine. Highly purified mutant enzyme K263S bound natural dNTP substrates and primed polynucleic acid substrates with equal affinity when compared to the wild type reverse transcriptase. No difference was observed in the binding of 3'-azido-2',3'-dideoxythymidine 5'-triphosphate to the mutant reverse transcriptase on the basis of Km and Ki determinations. The serine substitution had no effect on RNase H activity. These results indicate that lysine 263 is not essential in the binding of substrates to HIV-1 reverse transcriptase.

Effects of AIDS-related bereavement and HIV-related illness on psychological distress among gay men: a 7-year longitudinal study, 1985-1991

In this study we examined the influence of acquired immunodeficiency syndrome (AIDS)-related bereavement on psychological distress from 1985 through 1991. We predicted that this relation would be influenced by personal knowledge of human immunodeficiency virus (HIV) infection and symptoms consistent with HIV-related illness. Interview data collected each year on a cohort of 746 gay men included information on the deaths and illnesses of network members caused by AIDS, as well as on psychological distress, sedative use, HIV-related symptoms, and HIV infection status. Significant main effects of bereavement were found in each year after controlling for both losses occurring from 1 to 2 years previously and for AIDS and HIV health status. The intensity and duration of these bereavement effects diminished over time. Groups of men who were both bereaved and classified as having AIDS or were HIV positive reported the highest level of distress in every year compared with the 3 other groups.