Neurobehavioural testing in workers occupationally exposed to lead: systematic review and meta-analysis of publications

Although the toxic effects of lead on the central nervous system have been well described, the blood concentration at which lead begins to exert adverse effects remains the focus of debate. A meta-analysis of occupational studies was conducted evaluating the association between neurobehavioural testing results and moderate blood lead concentrations.

New reagents, reactions, and peptidomimetics for drug design

It has been a major focus in our laboratories to prepare novel reagents and peptidomimetic structures for drug design. We have designed and prepared novel guanidinylation reagents that can be employed in solution or as solid phase reagents. We and others have utilized the reagent 3-(diethoxyphosphoryloxy)-1,2,3-benzotriazin-4(3H)-one (DEPBT) for amide bond formation to couple sterically hindered structures. These couplings proceed with remarkably strong resistance to racemization. In the area of peptidomimetics, we have incorporated novel building blocks to create biologically active compounds. These building blocks include thioether and alkylamine bridges, beta-methylated, and beta,beta-dimethylated amino acid residues. These mimetic structures have been incorporated into specific target molecules such as opioids to obtain cyclic peptidomimetics with potent and selective biological activity.

Microsatellites in Zea - variability, patterns of mutations, and use for evolutionary studies

To evaluate the performance of microsatellites or simple sequence repeats (SSRs) for evolutionary studies in Zea, 46 microsatellite loci originally derived from maize were applied to diverse arrays of populations that represent all the diploid species of Zea and 101 maize inbreds. Although null phenotypes and amplification of more than two alleles per plant were observed at modest rates, no practical obstacle was encountered for applying maize microsatellites to other Zea species. Sequencing of microsatellite alleles revealed complex patterns of mutation including frequent indels in the regions flanking microsatellite repeats. In one case, all variation at a microsatellite locus came from indels in the flanking region rather than in the repeat motif. Maize microsatellites show great variability within populations and provide a reliable means to measure intraspecific variation. Phylogeographic relationships of Zea populations were successfully reconstructed with good resolution using a genetic distance based on the infinite allele model, indicating that microsatellite loci are useful in evolutionary studies in Zea. Microsatellite loci show a principal division between tropical and temperate inbred lines, and group inbreds within these two broad germplasm groups in a manner that is largely consistent with their known pedigrees.

Association of methylenetetrahydrofolate reductase polymorphism C677T and dietary folate with the risk of cervical dysplasia

Epidemiological studies have been inconsistent regarding a role for folate in the etiology of cervical dysplasia. Methylenetetrahydrofolate reductase (MTHFR) catalyzes the synthesis of 5-methyltetrahydrofolate, which is involved in the methylation of homocysteine to methionine. A common variant of this enzyme, resulting from a 677C-->T (Ala-->Val) substitution in the gene, has been shown to have reduced activity and is associated with mild hyperhomocysteinemia. A multiethnic case-control study was used to examine the association of dietary folate and MTHFR genotype with the odds ratios (ORs) for cervical dysplasia among women identified from several clinics on Oahu, Hawaii, between 1992 and 1996. We collected blood samples for DNA extraction, cervical smears for cytological diagnosis, exfoliated cervical cells for human papillomavirus (HPV) DNA testing, and personal interviews from 150 women with squamous intraepithelial lesions (SILs) and from 179 women with cytologically normal (Pap) smears. We found a positive, monotonic trend (P = 0.02) in the ORs for cervical SILs associated with the number of variant MTHFR T alleles, after multivariate adjustment. Women with the heterozygous CT genotype had twice the risk of cervical SILs [OR, 2.0; 95% confidence interval (CI), 1.1-3.7], and women with the homozygous TT genotype had almost three times the risk of SILs (OR, 2.9; 95% CI, 1.0-8.8) compared to women with the homozygous MTHFR CC genotype. The dietary intakes of folate, vitamin B(6), and vitamin B(12) were inversely related to the ORs for cervical SILs, after adjustment for HPV DNA and other confounders. The OR among women in the highest quartile compared with women in the lowest quartile of folate intake was 0.3 (95% CI, 0.1-0.7; P for trend = 0.002). Women with the variant T allele and folate intakes below the median were at significantly elevated risk of cervical SILs (OR, 5.0; 95% CI, 2.0-12.2) compared to women with CC alleles and folate intakes above the median. HPV infection was a strong risk factor for cervical dysplasia, particularly among women with the variant T allele (OR, 46.6; 95% CI, 15.9-136.2). All associations of MTHFR genotype with the ORs for cervical SILs were independent of other risk factors under study. These findings suggest that the MTHFR T allele and reduced dietary folate may increase the risk for cervical SILs.

A bicyclic and hsst2 selective somatostatin analogue: design, synthesis, conformational analysis and binding

A backbone bridged and disulfide bridged bicyclic somatostatin analogue, compound 1 (PTR-3205), was designed and synthesized by solid-phase methodology. The binding of compound 1 to the five different somatostatin receptors, expressed in CHO or COS-7 cells, indicate a high degree of selectivity towards hsstr2. The three-dimensional structure of this compound has been determined in DMSO-d(6) and in water by 1H NMR and by molecular dynamics simulations. Similar backbone conformations were observed in both solvents. We have established direct evidence that the backbone of this bicyclic somatostatin analogue assumes a 'folded' conformation in solution, where the lactam ring extends roughly in the plane of the beta-turn. The pharmacophoric region Phe-(D)-Trp-Lys-Thr of compound 1 is in accord with that of both the Veber compound L-363,301 (Merck) and sandostatin. We believe that the enhanced selectivity towards the hsst2 receptor, in comparison with other analogues, is due to its large hydrophobic region, composed of the lactam ring and the Phe side chains at positions 1 and 8.

Neonatal electroencephalogram does not predict cognitive and academic achievement scores at early school age in survivors of neonatal extracorporeal membrane oxygenation

Extracorporeal membrane oxygenation is an effective rescue treatment for severe cardiorespiratory failure in term or near-term neonates, although a wide range of neurologic sequelae have been noted in a substantial minority of survivors. The objective of the present study was to determine the value of the neonatal electroencephalogram (EEG) for predicting Wechler Preschool and Primary Scale of Intelligence-Revised (WPPSI-R), Wide Range Achievement Test, and Wide Range Assessment of Memory and Language scores at early school age in 66 testable survivors of extracorporeal membrane oxygenation who were not severely brain damaged. Technically satisfactory EEG recordings were obtained at least twice following admission to our nursery and prior to discharge. The EEGs were classified and graded according to standard criteria. The developmental test results of those who had only normal or mildly abnormal neonatal EEGs (group 1, n = 9) were compared with those who had at least one moderately or markedly abnormal recording (group 2, n = 57). School-age test and subtest scores were not statistically significantly worse in group 2 versus group 1 infants. No child in group 1 and five children in group 2 had WPPSI-R Full-Scale IQ scores of less than 70. Of the nine children in group 2 who had at least one markedly abnormal neonatal EEG recording (graded as burst suppression or as electrographic seizure), only two had abnormally low WPPSI-R Full-Scale IQ scores. We conclude that EEG recordings obtained during the neonatal course of neonates treated with extracorporeal membrane oxygenation do not predict cognitive and academic achievement test results in survivors at early school age who were testable and not severely brain damaged.

A bioactive somatostatin analog without a type II' beta-turn: synthesis and conformational analysis in solution

A cyclic somatostatin analog [structure: see text] (1) has been synthesized. Biological assays show that this compound has strong binding affinities to somatostatin hsst2 and hsst5 receptor subtypes (5.2 and 1.2 nM, respectively, and modest affinity to hsst4 (41.1 nM)). Our conformational analysis carried out in DMSO-d6 indicates that this compound exists as two structures arising from the trans and cis configurations of the peptide bond between Phe7 and N-alkylated Gly8. However, neither conformer exhibits a type II' beta-turn. This is the first report of a potent bioactive somatostatin analog that does not exhibit a type II' beta-turn in solution. Molecular dynamics simulations (500 ps) carried out at 300 K indicate that the backbone of compound 1 is more flexible than other cyclic somatostatin analogs formed by disulfide bonds.

Are the interpersonal and identity disturbances in the borderline personality disorder criteria linked to the traits of affective instability and impulsivity?

This study examines the degree to which two putative biologically influenced personality traits, affective instability and impulsive aggression, are associated with some of the interpersonal and intrapsychic disturbances of borderline personality disorder (BPD) and with choice of defense mechanism. In a sample of 152 personality disorder patients, affective instability and impulsive aggression were measured. Defense mechanisms were assessed in 140 of these patients using the Defensive Style Questionnaire (DSQ). The correlations between the traits of affective instability and impulsive aggression and the eight DSM-III-R criteria for borderline personality disorder and 20 DSQ defenses were examined. Affective instability was significantly correlated with the DSM-III-R criteria of identity disturbance, chronic emptiness or boredom, inappropriate anger, suicidality, and the affective instability criteria. It also was associated with the defenses of splitting, projection, acting out, passive aggression, undoing, and autistic fantasy. Impulsive aggression was related to unstable interpersonal relationships, inappropriate anger and impulsiveness and with the defense of acting out. It was negatively correlated with the defenses of suppression and reaction formation. A number of the interpersonal and experiential disturbances and defense mechanisms that are features of BPD are associated with the traits of affective instability and impulsive aggression among patients with personality disorders.

Suicide, impulsive aggression, and HTR1B genotype

BACKGROUND

Suicidality and impulsive aggression are partially heritable, and postmortem brain studies suggest that abnormalities in serotonin 1B may be associated with suicide. Studies of serotonin 1B "knockout" mice show an increase in aggressive behavior relative to wild-type mice.

METHODS

We assessed the relationship between genotype at the HTR1B locus and both suicide history and impulsive aggression in personality disorders.

RESULTS

The "G" allele of a polymorphic gene at the HTR1B locus was associated with a history of suicide attempts in white patients with personality disorders [chi(2)(1) = 9.3, p =.01, n = 90]. No relationship was found between HTR1B genotype and self-reported impulsive aggression.

CONCLUSIONS

This preliminary finding suggests that allelic variability at the HTR1B locus may be associated with the susceptibility to suicide attempts in patients with personality disorders.

Variability, Predictive Value, and Uses of the Beryllium Blood Lymphocyte Proliferation Test (BLPT): Preliminary Analysis of the Ongoing Workforce Survey

The beryllium blood lymphocyte proliferation test (BLPT) is used as a medical surveillance tool for assessment of persons at risk for developing clinical and subclinical chronic beryllium disease (CBD). Three laboratories, coded "A," "B," and "C," were used to perform the BLPTs, which involved two simultaneous tests on a split specimen. The intra-laboratory agreement analysis compared the first and the second test performed by the same laboratory. The interlaboratory agreement analysis compared test results performed by different laboratories on the same sample. The level of agreement was expressed as a kappa statistic. The positive predictive value (PPV) analysis compared BLPT results against the results of a bronchoscopy used to detect CBD. The data included 5483 records representing 3081 samples from 1510 persons. Intra-laboratory agreement was fair to moderate, with kappa values between 0.3 and 0.6. Inter-laboratory agreement was moderate (kappa = 0.5) for Labs A and B, moderate (kappa = 0.6) for Labs B and C, and poor (kappa = 0.2) for Labs A and C. A single unconfirmed abnormal test had a PPV for CBD of 39 percent, a confirmed (based on subsequent testing) abnormal test had a PPV for CBD of 45 percent, and a first-time double abnormal test had a PPV for CBD of 49 percent. Substantial inter- and intralaboratory disagreement exists between and within major laboratories that conduct this test.

CYP1A1, GSTM1, and GSTT1 polymorphisms and the risk of cervical squamous intraepithelial lesions in a multiethnic population

OBJECTIVE

In this investigation, we explored the hypothesis that genetic polymorphisms in the cytochrome P4501A1 (T3801C) and glutathione S-transferase classes mu and theta (GSTM1 and GSTT1) gene deletions promote the development of cervical dysplasia by moderating the activation and detoxification of polycyclic hydrocarbons and other compounds that influence oxidative stress and DNA adduct formation.

METHODS

A multiethnic, case-control study of 131 women with biopsy-confirmed cervical squamous intraepithelial lesions (SIL) and 180 controls with cytologically normal cervical (Pap) smears was conducted between 1992 and 1996 in Honolulu, Hawaii. We collected in-person interviews, a blood sample to extract genomic DNA, and an exfoliated cervical cell sample to determine the presence and type of human papillomavirus (HPV) using PCR dot-blot hybridization. Genotyping for the CYP1A1 MspI allelic variant and deletion of the GSTM1 and GSTT1 gene loci followed a PCR method.

RESULTS

Women who were homozygous, but not heterozygous, for the CYP1A1 MspI variant allele were at significantly increased risk of cervical SIL (odds ratio (OR) = 3.4; 95% confidence interval (CI) = 1.1-10.7) compared to women who were homozygous for the wild-type allele. Subjects with the GSTM1 null genotype had a nonsignificant elevated risk of cervical SIL (OR = 1.6; 95% CI = 0.8-3.0) compared to women with the gene present. No difference in the risk of cervical disease was associated with the GSTT1 null genotype. The combination of the CYP1A1 homozygous variant and the GSTM1 null genotypes increased the odds ratio for cervical SIL to 5.1 (95% CI = 1.3-20.7). There was no evidence for an interaction between genotype and exposure to tobacco smoke, alcohol drinking, or HPV DNA positivity.

CONCLUSIONS

These findings, although based on a small number of subjects, suggest that the CYP1A1 MspI polymorphism may be a susceptibility factor for early, premalignant changes in the cervical epithelium.

Evolution of nuclear- and mitochondrial-encoded subunit interaction in cytochrome c oxidase

Mitochondrial DNA (mtDNA)-encoded proteins function in eukaryotes as subunits of respiratory complexes that also contain nuclear DNA (nDNA)-encoded subunits. The importance of functional interactions between mtDNA- and nDNA-encoded proteins was previously demonstrated by testing the survivability of cybrid cells or individuals containing nDNA and mtDNA from different populations or species. This report focuses on the multisubunit respiratory complex cytochrome c oxidase (COX), made up of both mtDNA-encoded and nDNA-encoded subunits. A combination of evolutionary and crystallographic data is employed to determine whether rates of nonsynonymous substitutions have been higher, the same, or lower for residues in close proximity that are encoded by a different genome (nDNA or mtDNA). This determination is performed by simply taking the ratio, called the interaction ratio i, of the nonsynonymous substitution rate of the close-contact residues to the nonsynonymous substitution rate of the noncontact residues. We assume that the close-contact residues (which are more likely to interact) are functionally important and that, therefore, amino acid replacements among these residues cannot escape the scrutiny of natural selection. i = 1 indicates that the close-contact residues have been under neither greater purifying selection nor greater positive selection than the noncontact residues as a specific consequence of their being encoded by separate genomes. i < 1 indicates that the close-contact residues have been under greater purifying selection but less positive selection than have the noncontact residues. Conversely, i > 1 indicates that the close-contact residues have been under less purifying but greater positive selection than have the noncontact residues. i < 1 may be referred to as a constraining interaction; i.e., the close-contact residues compared with the noncontact residues appear to be under greater structural-functional constraints. On the other hand, i > 1 may be referred to as an optimizing interaction; i.e., apparently many different amino acid replacements are required to optimize this subunit's interaction with the other subunit. A major finding is that the nDNA-encoded residues in close physical proximity to mtDNA-encoded residues evolve more slowly than the other nuclear-encoded residues (and thus display a constraining interaction), whereas the mtDNA-encoded residues in close physical proximity to nDNA-encoded residues evolve more rapidly than the other mitochondrial-encoded residues (and thus display an optimizing interaction). A possible reason for this striking difference between the nuclear- and mitochondrial-encoded COX subunits in how their functional interaction evolves is discussed.

A Novel Traceless Resin-Bound Guanidinylating Reagent for Secondary Amines To Prepare N,N-Disubstituted Guanidines

[reaction: see text]. We report the development of a solid support-linked guanidinylating reagent. This reagent consists of a urethane-protected triflyl guanidine attached to the resin via a carbamate linker. It allows for rapid synthesis of guanidines from a variety of amines. It provides access to N-alkyl/aryl- or N,N-dialkylguanidines under mild conditions. Cleavage with 50% TFA produces target molecules in high yields and purity. The ability to guanidinylate secondary amines is a significant feature of this guanidinylating reagent.

Ovulation timing. Concepts and controversies

While the luteinizing hormone (LH) surge has long been accepted as the key event in the estrous cycle of the bitch, historically, there has been no practical way to identify it. In the past, the veterinary practitioner had to rely on general and/or subjective information received from vaginal cytology, physical examinations, and observations. With the recent development of in-clinic progesterone and LH assays, and the wider availability of laboratory quantitative progesterone assays, the LH surge can either be identified directly or estimated by the detection of changes in progesterone. As a result, ovulation time can now be predicted with high accuracy in a private practice setting.