Characterization of CYP2D6 Pharmacogenetic Variation in Sub-Saharan African Populations

Cytochrome P450 2D6 (CYP2D6) is a key enzyme in drug response owing to its involvement in the metabolism of ~ 25% of clinically prescribed medications. The encoding CYP2D6 gene is highly polymorphic, and many pharmacogenetics studies have been performed worldwide to investigate the distribution of CYP2D6 star alleles (haplotypes); however, African populations have been relatively understudied to date. In this study, the distributions of CYP2D6 star alleles and predicted drug metabolizer phenotypes-derived from activity scores-were examined across multiple sub-Saharan African populations based on bioinformatics analysis of 961 high-depth whole genome sequences. This was followed by characterization of novel star alleles and suballeles in a subset of the participants via targeted high-fidelity Single-Molecule Real-Time resequencing (Pacific Biosciences). This study revealed varying frequencies of known CYP2D6 alleles and predicted phenotypes across different African ethnolinguistic groups. Twenty-seven novel CYP2D6 star alleles were predicted computationally and two of them were further validated. This study highlights the importance of studying variation in key pharmacogenes such as CYP2D6 in the African context to better understand population-specific allele frequencies. This will aid in the development of better genotyping panels and star allele detection approaches with a view toward supporting effective implementation of precision medicine strategies in Africa and across the African diaspora.

CYP2B6*6 and CYP2B6*18 Predict Long-Term Efavirenz Exposure Measured in Hair Samples in HIV-Positive South African Women

Long-term exposure to efavirenz (EFV) measured in hair samples may predict response to antiretroviral treatment (ART). Polymorphisms in CYP2B6 are known to alter EFV levels. The aim of this study was to assess the relationship between CYP2B6 genotype, EFV levels measured in hair, and virological outcomes on ART in a real-world setting. We measured EFV levels in hair from HIV-positive South African females who had been receiving EFV-based treatment for at least 3 months from the South African Black (SAB) (n = 81) and Cape Mixed Ancestry (CMA) (n = 53) populations. Common genetic variation in CYP2B6 was determined in 15 individuals from each population using bidirectional Sanger sequencing. Prioritized variants (n = 16) were subsequently genotyped in the entire patient cohort (n = 134). The predictive value of EFV levels in hair and selected variants in CYP2B6 on virological treatment outcomes was assessed. Previously described alleles (CYP2B6*2, CYP2B6*5, CYP2B6*6, CYP2B6*17, and CYP2B6*18), as well as two novel alleles (CYP2B6*31 and CYP2B6*32), were detected in this study. Compared to noncarriers, individuals homozygous for CYP2B6*6 had ∼109% increased EFV levels in hair (p = .016) and CYP2B6*18 heterozygotes demonstrated 82% higher EFV hair levels (p = .0006). This study confirmed that alleles affecting CYP2B6 metabolism and subsequent EFV exposure are present at significant frequencies in both the SAB and CMA populations. Furthermore, this study demonstrated that the use of hair samples for testing EFV concentrations may be a useful tool in determining long-term drug exposure in resource-limited countries.

Modified diadenosine tetraphosphates with dual specificity for P2Y1 and P2Y12 are potent antagonists of ADP-induced platelet activation

BACKGROUND

Diadenosine 5',5'''-P(1),P(4)-tetraphosphate (Ap(4)A), a natural compound stored in platelet dense granules, inhibits ADP-induced platelet aggregation. Ap(4)A inhibits the platelet ADP receptors P2Y(1) and P2Y(12), is a partial agonist of P2Y(12), and is a full agonist of the platelet ATP-gated ion channel P2X1. Modification of the Ap(4)A tetraphosphate backbone enhances inhibition of ADP-induced platelet aggregation. However, the effects of these Ap(4)A analogs on human platelet P2Y(1), P2Y(12) and P2X1 are unclear.

OBJECTIVE

To determine the agonist and antagonist activities of diadenosine tetraphosphate analogs towards P2Y(1), P2Y(12), and P2X1.

METHODS

We synthesized the following Ap(4)A analogs: P(1),P(4)-dithiotetraphosphate; P(2),P(3)-chloromethylenetetraphosphate; P(1)-thio-P(2),P(3)-chloromethylenetetraphosphate; and P(1),P(4)-dithio-P(2),P(3)-chloromethylenetetraphosphate. We then measured the effects of these analogs on: (i) ADP-induced platelet aggregation; (ii) P2Y(1)-mediated changes in cytosolic Ca(2+); (iii) P2Y(12)-mediated changes in vasodilator-stimulated phosphoprotein phosphorylation; and (iv) P2X1-mediated entry of extracellular Ca(2+).

RESULTS

Ap(4)A analogs with modifications in the phosphate backbone inhibited both P2Y(1) and P2Y(12), and showed no agonist activity towards these receptors. The dithio modification increased inhibition of P2Y(1), P2Y(12), and platelet aggregation, whereas the chloromethylene modification increased inhibition of P2Y(12) and platelet aggregation, but decreased P2Y(1) inhibition. Combining the dithio and chloromethylene modifications increased P2Y(1) and P2Y(12) inhibition. As compared with Ap(4)A, each modification decreased agonist activity towards P2X1, and the dual modification completely eliminated P2X1 agonist activity.

CONCLUSIONS

As compared with Ap(4)A, tetraphosphate backbone analogs of Ap(4)A have diminished activity towards P2X1 but inhibit both P2Y(1) and P2Y(12) and, with greater potency, inhibit ADP-induced platelet aggregation. Thus, diadenosine tetraphosphate analogs with dual receptor selectivity may have potential as antiplatelet drugs.

Psychiatric genetics in South Africa: cutting a rough diamond

Psychiatric disorders place a considerable healthcare burden on South African society. Incorporating genetic technologies into future treatment plans offers a potential mechanism to reduce this burden. This review focuses on psychiatric genetic research that has been performed in South African populations with regards to obsessive-compulsive disorder, schizophrenia and bipolar disorder. Preliminary findings from these studies suggest that data obtained in developed countries cannot necessarily be extrapolated to South African population groups. Psychiatric genetic studies in South Africa seem to involve relatively low-cost methodologies and only a limited number of large national collaborative studies. Future research in South Africa should therefore aim to incorporate high-throughput technologies into large scale psychiatric studies through the development of collaborations. On a global level, the vast majority of psychiatric genetic studies have been performed in non-African populations. South Africa, as the leading contributor to scientific research in Africa, may provide a foundation for addressing this disparity and strengthening psychiatric genetic research on the continent. Although the elucidation of the genetic architecture of psychiatric disorders has proved challenging, examining the unique genetic profiles found in South African populations could provide valuable insight into the genetics of psychiatric disorders.

Improving the quality of outpatient care for older patients with diabetes: lessons from a comparison of rural and urban communities

OBJECTIVE

Our goal was to compare the quality of diabetic care received by patients in rural and urban communities.

STUDY DESIGN

We performed a retrospective analysis of claims data captured by the Medicare program.

POPULATION

We included all fee-for-service Medicare patients 65 years and older living in the state of Washington who had 2 or more physician encounters for diabetes care during 1994.

OUTCOME MEASURES

The outcomes were the extent to which patients received 3 specific recommended services: glycated hemoglobin determination, cholesterol measurement, and eye examination.

RESULTS

A total of 30,589 Medicare patients (8.4%) were considered to have diabetes; 29.1% lived in rural communities. Generalists provided most diabetic care in all locations. Patients living in small rural towns received almost half their outpatient care in larger communities. Patients living in large rural towns remote from metropolitan areas were more likely to have received the recommended tests than patients in all other groups. Patients who saw an endocrinologist at least once during the year were more likely to have received the recommended tests.

CONCLUSIONS

Large rural towns may provide the best conditions for high-quality care: They are vibrant, rapidly growing communities that serve as regional referral centers and have an adequate-but not excessive-supply of both generalist and specialist physicians. Generalists provide most diabetic care in all settings, and consultation with an endocrinologist may improve adherence to guidelines.

Effects of stress management on pain behavior in rheumatoid arthritis

OBJECTIVE

To examine the effects of stress management training on pain behavior exhibited by persons with rheumatoid arthritis (RA) and the relationship of change in pain behavior with certain patient characteristics as well as change in self-reported levels of pain.

METHODS

Patients with RA (n = 131) were randomly assigned to 1 of 3 groups: a stress management group, an attention control group, or a standard care control group. The stress management and attention control groups received a 10-week intervention followed by a 15-month maintenance phase.

RESULTS

The 3 groups did not differ significantly in the change in pain behavior at any of the assessment periods. However, persons with RA who had less disease activity tended to exhibit positive changes in pain behavior over time. Changes in self-reported pain were not significantly related to changes in pain behavior.

CONCLUSION

The results indicate that stress management interventions do not reduce total pain behaviors exhibited by persons with RA. Changes in pain behaviors appear to be related to disease activity, age, and disease duration, but not to changes in self-reported measures of pain.

Stress management in rheumatoid arthritis: what is the underlying mechanism?

OBJECTIVE

To test whether change in cognitive-behavioral variables (such as self-efficacy, coping strategies, and helplessness) is a mediator in the relation between cognitive behavior therapy and reduced pain and depression in persons with rheumatoid arthritis (RA).

METHODS

A sample of patients with RA who completed a stress management training program (n = 47) was compared to a standard care control group (n = 45). A path analysis testing a model including direct effects of comprehensive stress management training on pain and depression and indirect effects via change in cognitive-behavioral variables was conducted.

RESULTS

The path coefficients for the indirect effects of stress management training on pain and depression via change in cognitive-behavioral variables were statistically significant, whereas the path coefficients for the direct effects were found not to be statistically significant.

CONCLUSION

Decreases in pain and depression following stress management training are due to beneficial changes in the arenas of self-efficacy (the belief that one can perform a specific behavior or task in the future), coping strategies (an individual's confidence in his or her ability to manage pain), and helplessness (perceptions of control regarding arthritis). There is little evidence of additional direct effects of stress management training on pain and depression.

In vitro antimicrobial activities of novel anilinouracils which selectively inhibit DNA polymerase III of gram-positive bacteria

The 6-anilinouracils are novel dGTP analogs that selectively inhibit the replication-specific DNA polymerase III of gram-positive eubacteria. Two specific derivatives, IMAU (6-[3'-iodo-4'-methylanilino]uracil) and EMAU (6-[3'-ethyl-4'-methylanilino]uracil), were substituted with either a hydroxybutyl (HB) or a methoxybutyl (MB) group at their N3 positions to produce four agents: HB-EMAU, MB-EMAU, HB-IMAU, and MB-IMAU. These four new agents inhibited Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus faecalis, and Enterococcus faecium. Time-kill assays and broth dilution testing confirmed bactericidal activity. These anilinouracil derivatives represent a novel class of antimicrobials with promising activities against gram-positive bacteria that are resistant to currently available agents, validating replication-specific DNA polymerase III as a new target for antimicrobial development.

Novel nonsubstrate inhibitors of human thymidine phosphorylase, a potential target for tumor-dependent angiogenesis

Thymidine phosphorylase/platelet-derived endothelial cell growth factor (TP/PD-ECGF) is an enzyme involved in thymidine metabolism and homeostasis, and its catalytic activity appears to play an important role in angiogenesis. Here we describe the cloning and expression of a His-tagged human TP/PD-ECGF and its assay with uracil and thymine analogues. We present the design, synthesis, and biological evaluation of novel 6-(phenylalkylamino)uracil derivatives which, at micromolar concentrations, inhibit both catabolic and anabolic reactions of human TP in vitro. These base analogues are not converted by the enzyme into the nucleoside form, thus representing pure nonsubstrate inhibitors of the enzyme.

The effect of the doctor-patient relationship on emergency department use among the elderly

OBJECTIVES

This study sought to determine the rate of emergency department use among the elderly and examined whether that use is reduced if the patient has a principal-care physician.

METHODS

The Health Care Financing Administration's National Claims History File was used to study emergency department use by Medicare patients older than 65 years in Washington State during 1994.

RESULTS

A total of 18.1% of patients had 1 or more emergency department visits during the study year; the rate increased with age and illness severity. Patients with principal-care physicians were much less likely to use the emergency department for every category of disease severity. After case mix, Medicaid eligibility, and rural/urban residence were controlled for, the odds ratio for having any emergency department visit was 0.47 for patients with a generalist principal-care physician and 0.58 for patients with a specialist principal-care physician.

CONCLUSIONS

The rate of emergency department use among the elderly is substantial, and most visits are for serious medical problems. The presence of a continuous relationship with a physician--regardless of specialty--may reduce emergency department use.

A confirmatory factor analysis of the Center for Epidemiologic Studies Depression Scale in rheumatoid arthritis patients: additional evidence for a four-factor model

OBJECTIVE

To examine the factor structure of the Center for Epidemiologic Studies Depression Scale (CES-D) in a sample of patients with rheumatoid arthritis (RA), testing all of the alternative models suggested by the previous evidence.

METHODS

The CES-D was administered to a group of RA patients (n = 685) during a structured telephone interview. The telephone interview was repeated 6 months later (n = 537) and 12 months later (n = 453). Confirmatory factor analyses were conducted to test alternative models.

RESULTS

The correlated 4-factor model and the second-order 4-factor model were the best fitting models.

CONCLUSION

The factor structure of the CES-D previously found in the general population was replicated in an RA sample. The results are consistent with previous evidence of criterion contamination in the CES-D when used in an RA sample and provide support for the view that a single summary score may not be the most informative index of the CES-D.

Sensitivity of bacteriophage RB69 DNA polymerase to N2-(p-n-butylphenyl)-2'-deoxyguanosine nucleotides

The response of bacteriophage RB69 DNA polymerase to N2-(p-n-butylphenyl)-2'-deoxyguanosine 5'-triphosphate (BuPdGTP), related nucleotides and non-nucleoside inhibitors was measured and compared to values obtained for the closely related DNA polymerase from bacteriophage T4. Both enzymes showed similar responses to inhibitors in terms of Ki values and the ability to utilize BuPdGTP as a substrate. These results provide the relevance of using the recent crystal structure of RB69 DNA polymerase for analysis of BuPdGTP/B family DNA polymerase interactions.

Inhibitors of DNA polymerase III as novel antimicrobial agents against gram-positive eubacteria

6-Anilinouracils are selective inhibitors of DNA polymerase III, the enzyme required for the replication of chromosomal DNA in gram-positive bacteria (N. C. Brown, L. W. Dudycz, and G. E. Wright, Drugs Exp. Clin. Res. 12:555-564, 1986). A new class of 6-anilinouracils based on N-3 alkyl substitution of the uracil ring was synthesized and analyzed for activity as inhibitors of the gram-positive bacterial DNA polymerase III and the growth of gram-positive bacterial pathogens. Favorable in vitro properties of N-3-alkyl derivatives prompted the synthesis of derivatives in which the R group at N-3 was replaced with more-hydrophilic methoxyalkyl and hydroxyalkyl groups. These hydroxyalkyl and methoxyalkyl derivatives displayed K(i) values in the range from 0.4 to 2.8 microM against relevant gram-positive bacterial DNA polymerase IIIs and antimicrobial activity with MICs in the range from 0.5 to 15 microg/ml against a broad spectrum of gram-positive bacteria, including methicillin-resistant staphylococci and vancomycin-resistant enterococci. Two of these hydrophilic derivatives displayed protective activity in a simple mouse model of lethal staphylococcal infection.

Molecular modeling and synthesis of inhibitors of herpes simplex virus type 1 uracil-DNA glycosylase

We recently reported the properties of the first selective inhibitors of herpes simplex virus type 1 (HSV1) uracil-DNA glycosylase (UDG), an enzyme of DNA repair that has been proposed to be required for reactivation of the virus from latency. 6-(4-Octylanilino)uracil (octAU) was the most potent inhibitor among a series of 6-(4-alkylanilino)uracils, acting in the micromolar range and without effect against human UDG. A 28.5-kDa catalytic fragment of HSV1 UDG has been crystallized in the presence of uracil, and the structure was recently solved. We have used the coordinates of this structure in order to study interaction of our inhibitors with the enzyme, and a model of binding between octAU and UDG has been derived. Starting with the optimized model, the activity of several octAU analogues was predicted, and the values compared favorably with experimental results found for the synthetic compounds. Several hydrophilic derivatives were predicted and found to be active as UDG inhibitors. These compounds will be useful to determine if UDG, like the viral thymidine kinase, is required for reactivation of HSV1 from latency in nerve cells.

6-Anilinouracil-based inhibitors of Bacillus subtilis DNA polymerase III: antipolymerase and antimicrobial structure-activity relationships based on substitution at uracil N3

6-Anilinouracils (6-AUs) are dGTP analogues which selectively inhibit the DNA polymerase III of Bacillus subtilis and other Gram-positive bacteria. To enhance the potential of the 6-AUs as antimicrobial agents, a structure-activity relationship was developed involving substitutions of the uracil N3 position in two 6-AU platforms: 6-(3,4-trimethyleneanilino)uracil (TMAU) and 6-(3-ethyl-4-methylanilino)uracil (EMAU). Series of N3-alkyl derivatives of both 6-AUs were synthesized and tested for their ability to inhibit purified B. subtilis DNA polymerase III and the growth of B. subtilis in culture. Alkyl groups ranging in size from ethyl to hexyl enhanced the capacity of both platforms to bind to the polymerase, and with the exception of hexyl, they also significantly enhanced their antimicrobial potency. N3 substitution of the EMAU platform with more hydrophilic hydroxyalkyl and methoxyalkyl groups marginally enhanced anti-polymerase III activity but enhanced antibacterial potency severalfold. In sum, the results of these studies indicate that the ring N3 of 6-anilinouracils can tolerate substituents of considerable size and structural variety and, thus, can be manipulated to significantly enhance the antibacterial potency of this novel class of polymerase III-specific inhibitors.

Hospital choice of Medicare beneficiaries in a rural market: why not the closest?

As part of a larger study of hospital choice, the travel patterns of more than 12,000 Medicare beneficiaries residing in three overlapping rural areas were examined. During 1986 these Medicare beneficiaries were admitted to one of 53 hospitals in an area that encompassed parts of Minnesota, North Dakota, and South Dakota. Information on ZIP code of residence, closest hospital, and hospital of admission were used to analyze hospital choices of the Medicare rural elderly residing in this area. To summarize their travel patterns, the admitting hospital was categorized based on whether it was urban or rural, its size and whether or not it was the closest facility. Findings indicated that 60 percent of these rural Medicare beneficiaries used hospital services at their closest rural hospital, regardless of its size. However, 79 percent of those whose closest hospital was larger than 75 beds used it, while only 54 percent of those whose closest rural hospital was fewer than 75 beds obtained services there. Overall, 30 percent of those residing in this rural market area went to an urban hospital. These patterns appeared to reflect an evaluation by the physician and/or individual of the relative attractiveness of the local hospital versus alternatives available, as well as the individual's characteristics. Travel patterns varied by the beneficiary's age as well as his or her relative complexity of illness, as measured by a Disease Staging methodology. Findings have implications for the provision and financing of hospital services in rural areas.

Synthesis and molecular modeling of novel HSV1 uracil-DNA glycosylase inhibitors

In a recent paper the first selective inhibitors of HSV1 uracil-DNA glycosylase (UDG) acting in the micromolar range have been reported. A 28.5 kDa catalytic fragment of HSV1 UDG has been crystallized in the presence of uracil, and the structure was recently solved. Starting with the optimized model of binding between 6-(4'-n-octylanilino)uracil (octAU) and UDG some new derivatives have been predicted to be active. In vitro studies with the novel synthetized compounds confirm the plausibility of the model and define the structure features for UDG inhibitors.

Synthesis and biochemical study of N2-(p-n-butylphenyl)-2'-deoxyguanosine 5'-(alpha,beta-imido)triphosphate (BuPdGMPNHPP): a non-substrate inhibitor of B family DNA polymerases

BuPdGMPNHPP was synthesized and assayed as a non-incorporable inhibitor of B family DNA polymerases. The derivative was synthesized by preparation of the imidophosphorane of BuPdG followed by reaction with orthophosphate using the imidazolide method. BuPdGMPNHPP inhibited human DNA polymerase alpha and T4 DNA polymerase 10 and 3.5-times more potently than BuPdGTP, respectively, and was not a substrate for either enzyme. BuPdGMPNHPP acts as an active site affinity probe that could find use in co-crystallization trials of B family DNA polymerases.

The role of leucine residues in the structure and function of a leucine zipper peptide inhibitor of paramyxovirus (NDV) fusion

To investigate the molecular mechanisms involved in paramyxovirus-induced cell fusion, the function and structure of synthetic peptide analogs of the sequence from the leucine zipper region (heptad repeat region 2) of the Newcastle disease virus fusion protein (F) were characterized. As previously reported (Young et al., Virology, 238, 291), a peptide with the sequence ALDKLEESNSKLDKVNVKLT (amino acids 478-497 of the F protein) inhibited syncytia formation after transfection of Cos cells with the hemagglutinin-neuraminidase and F protein cDNAs. A peptide analog which had an alanine residue in place of the first leucine residue in the zipper motif (ALDKAEESNSKLDKVNVKLT) retained inhibitory activity but less than the original peptide. Further loss in activity was observed in a peptide in which two of the leucine residues were replaced with alanine (ALDKAEESNSKADKVNVKLT), and a peptide which had all leucine residues in the zipper motif replaced with alanine (ALDKAEESNSKADKVNVKLT) had no inhibitory activity. The three-dimensional conformations of these peptides in aqueous solution were determined through the use of nuclear magnetic spectroscopy and molecular modeling. Results showed that while the wild-type peptide formed a helix with properties between an alpha-helix and a 3(10) helix with leucine residues aligned along one face of the helix, progressive substitution of leucine residues with alanine resulted in the progressive loss of helical structure. The results suggest that alterations of leucine residues in the zipper motif disrupt secondary structure of the peptide and that this structure is critical to the inhibitory activity of the peptide.

Age, depressive symptoms, and rheumatoid arthritis

OBJECTIVE

To examine the relationship between age and depression in persons with rheumatoid arthritis (RA).

METHODS

Two separate outpatient cohorts of persons with RA were studied. In both studies, the Center for Epidemiological Studies Depression Scale was administered to all subjects, and the prevalence of depressive symptoms was determined by age group. In the second study, data on additional measures of disease activity, pain, life stress, and coping were collected for use in multiple linear regression analyses.

RESULTS

In both samples, a significant correlation between age and depression was found; younger persons (age < or = 45 years) with RA were significantly more depressed, even after controlling for potentially confounding variables such as sex, marital status, antidepressant medication, arthritis medication, functional class, and disease duration.

CONCLUSION

The findings show that younger persons with RA are at higher risk for depressive symptoms than their older counterparts.

Analysis of a peptide inhibitor of paramyxovirus (NDV) fusion using biological assays, NMR, and molecular modeling

To investigate the molecular mechanisms involved in paramyxovirus-induced cell fusion, the function and structure of a peptide with a 20-amino-acid sequence from the leucine zipper region (heptad repeat region 2) of the Newcastle disease virus fusion protein (F) were characterized. A peptide with the sequence ALDKLEESNSKLDKVNVKLT (amino acids 478-497 of the F protein) was found to inhibit syncytia formation after virus infection and after transfection of Cos cells with the HN (hemagglutinin-neuraminidase) and F protein cDNAs. Using an F protein gene that requires addition of exogenous trypsin for cleavage, it was shown that the peptide exerted its inhibitory effect prior to cleavage. The three-dimensional conformation of the peptide in aqueous solution was determined through the use of NMR and molecular modeling. Results showed that the peptide formed a helix with properties between an alpha-helix and a 3(10)-helix and that leucine residues aligned along one face of the helix. Side chain salt bridges and hydrogen bonds likely contributed to the stability of the peptide secondary structure. Analysis of the aqueous solution conformation of the peptide suggested mechanisms for specificity of interaction with the intact F protein.

Structural studies by 1H NMR of a prototypic alpha-helical peptide (LYQELQKLTQTLK) and homologs in trifluoroethanol/water and on sodium dodecyl sulfate micelles

The 1H NMR-determined structure and dynamics of a synthetic, amphiphilic alpha-helical peptide, PH-1.0 (LYQELQKLTQTLK), and several homologs were compared in 50% trifluoroethanol-d2 (TFE-d2)/H20 and in sodium dodecyl-d25 sulfate (SDS-d25) micelles. The peptides were designed to test the influence on secondary structure of placement of favored and disfavored residues relative to a "longitudinal, hydrophobic strip-of-helix" defined by the repeating leucines. PH-1.0 was highly ordered as an alpha-helix in 50% TFE-d2/H20 and in SDS-d25 micelles. Homologs PH-1.1, in which L1 was replaced by T, and PH-1,4, in which L12 was replaced by T. were found to be partially helical in both media. Calculated structures in SDS-d25 revealed that the helix of PH-1.1 was slightly disordered at the N-terminus, but that of PH-1.4 was completely disordered at the C-terminus. Examination of distributions of hydrophobic residues in protein structures revealed that, when [symbol: see text] = LIVFM and [symbol: see text] = nonLIVFM, the pattern [symbol: see text] is favored and [symbol: see text] is disfavored in alpha-helices. Several analogs of PH-1.0 incorporating these patterns were studied. Peptide PH-1.12 (LYQELQKLLQTLK) retained alpha-helical structure in both 50% TFE-d2/H20 and in SDS-d25 micelles. However, although PH-1.13 (LYQELQKLTLTLK) was fully helical in 50% TFE, it was helical only through residue 6 in SDS micelles. Two homologs containing an additional loop of the helix and repeats of favored (PH-5.0, NYLQTLLETLKTLLQK) or suppressed LL patterns (PH-5.11, NYLQTLETLKLTQK) gave similar results, i.e. the latter peptide was helical only through residue 6 in SDS micelles. The degree of local order in these SDS micelle-adsorbed peptides correlates to placement of hydrophobic residues in motifs which are favored or disfavored in proteins in general and in alpha-helices specifically.

The importance of enhancing self-efficacy in rheumatoid arthritis

OBJECTIVE

To examine relationships among changes in self-efficacy and changes in other clinically relevant outcome measures.

METHOD

Subjects (n = 44) were participants in a prospective, randomized stress-management study followed over 15 months. Outcome measures included self-efficacy, depression, pain, health status, and disease activity.

RESULTS

Correlational analyses revealed significant associations between changes in self-efficacy (particularly total self-efficacy) and changes in selected measures of depression, pain, health status, and disease activity. The observed associations were not due to changes in medication regimen or to nonadherence to the stress-management program.

CONCLUSIONS

Evidence is provided that induced changes in self-efficacy following a stress-management program were significantly related to other clinically important outcome measures.

Synthesis and effect of nonhydrolyzable xanthosine triphosphate derivatives on prenylation of Rab5D136N

A novel and convenient method for nucleoside triphosphate synthesis was applied to the preparation of potentially nonhydrolyzable xanthosine triphosphate derivatives. The N-methylimidazolide of xanthosine 5'-monophosphate reacted rapidly with methylenediphosphonic acid and imidodiphosphonic acid to give xanthosine 5'-(beta, gamma-methylene)triphosphate and xanthosine 5'-(beta, gamma-imido)triphosphate, respectively, in good yields. Both compounds inhibited the xanthosine-diphosphate-dependent prenylation of a mutant of Rab5, Rab5D136N, the nucleotide specificity of which had been converted from GTP to xanthosine triphosphate. The results indicate that xanthosine 5'-(beta, gamma-methylene)triphosphate and xanthosine 5'-(beta, gamma-imido)triphosphate bound to the mutant protein with similar affinities and were not hydrolyzed under the assay conditions. These novel derivatives may be useful tools for the study of the role of individual GTPases mutated to xanthosine triphosphate specificity in the background of other GTP-binding proteins.

Effect of 9-(4-hydroxybutyl)-N2-phenylguanine (HBPG), a thymidine kinase inhibitor, on clinical recurrences of ocular herpetic keratitis in squirrel monkeys

9-(4-Hydroxybutyl)-N2-phenylguanine (HBPG) is a new viral thymidine kinase inhibitor that we tested for the ability to prevent recurrences of herpetic keratitis. Eighteen squirrel monkeys (Saimiri scuireus) were infected in both corneas with the Rodanus strain of herpes simplex virus type 1 (HSV-1). All corneas showed typical dendritic keratitis 3 days after infection, followed by spontaneous healing. On day 21, the monkeys were randomized into two coded groups and ocular examinations were begun. One group received intraperitoneal (i.p.) injections of HBPG, 150 mg/kg, in a corn oil suspension every 8 h, and the other group received i.p. injections of the corn oil vehicle only. On day 22, recurrences were induced by reducing the temperature of the room in the late afternoon so that a low of 18 degrees C was achieved during the night. After the morning treatment, room temperature was raised to the normal ambient temperature (24-27 degrees C), and treatment was discontinued. Treatment was reinstituted on day 27, the room temperature was lowered again on day 28, and treatment was again discontinued as before. Third and fourth cycles of treatment and cold stress were begun on days 34 and 69. Ocular examinations were continued until day 73, at which point the code was broken. We found that the HBPG treatment significantly reduced the number of corneas with recurrences during the treatment periods, compared with recurrences in untreated, cold-stressed animals (P = 0.01).

A biopsychosocial model of disability in rheumatoid arthritis

OBJECTIVE

To test and cross-validate a model using disease activity, pain, and helplessness to predict future psychological and physical disability in persons with rheumatoid arthritis (RA) across time.

METHODS

Measures of disease activity, pain, helplessness, psychological function, and physical function were collected from 63 males with RA at baseline, 3 months, and 6 months. Path analytic methods were used to examine longitudinal relationships among these variables.

RESULTS

Path analysis revealed that pain and helplessness were significant mediators of the relationship between disease activity and future disability in RA; the predictive model withstood two cross-validations.

CONCLUSION

The findings suggest that pain and helplessness are key biopsychosocial variables that affect the development of disability in RA.

Risk factors for depression in rheumatoid arthritis

OBJECTIVE

To identify risk factors for the development of depression in persons with rheumatoid arthritis (RA).

METHODS

Subjects were divided into depressed versus nondepressed groups on the basis of the Center for Epidemiologic Studies-Depression Scale; a range of psychological, pain-related, disease-related, and demographic variables were analyzed to predict depression. Both cross-sectional and longitudinal predictive models were examined.

RESULTS

A series of analyses, including multiple logistic regression, found that the optimal predictors of depression in RA were average daily stressors, confidence in one's ability to cope, and degree of physical disability. The model was successfully cross-validated on separate data sets (i.e., same subjects at different time points).

CONCLUSION

All of the identified risk factors for depression in RA are preventable to some extent and, therefore, should be addressed in comprehensive, rheumatology team care.

1H NMR studies of prototypical helical designer peptides. A comparative study of the amide chemical shift dependency on temperature and polypeptide sequence

A series of designer alpha-helical peptides with hydrophobic residues located at different positions along the sequence (PH-1.0 = LYQELQKLTQTLK, PH-1.19 = LYQELQKLTQTFK, PH-1.12 = LYQELQKLLQTLK, PH-1.13 = LYQELQKLTLTLK, PH-1.4 = LYQELQKLTQTTK) were analyzed using one- and two-dimensional NMR methods (TOCSY and NOESY). The central feature of these designer peptides is the incorporation of a maximal hydrophobic strip which may play a role in antigen processing and the nucleation of alpha-helices in proteins (J. Immunol. 145, 899, 1990). Using the 2D-NMR, sequence specific assignments and NOE connectivities were determined in all peptides when dissolved in H2O/TFE mixtures. NOE connectivities indicated that all these peptides are helical in this medium. An unusually large number of NOEs was found for all these designer peptides. This is in accord with ultracentrifugation studies that showed that PH-1.0 forms a trimer in 50% H2O/TFE mixtures. Other peptides in the series behave in similar manner as PH-1.0. The structural differences among these peptides was addressed using the backbone amide chemical shift temperature coefficients, [symbol: see text], and the differences between the observed and random coil values, delta delta HN. The delta delta HN patterns along the peptide sequence are consistent with those expected for amphiphilic alpha-helices, where most delta delta HN values are below zero. However, no significant differences among the peptides in this series can be detected on the delta delta HN patterns, with the exception of PH-1.12. The [symbol: see text] values reveal differences among the peptides of the series. The patterns of [symbol: see text] along the peptide sequences are similar to that found for delta delta HN for PH-1.0, PH-1.19 and PH-1.4. The other peptides in the series, PH-1.12 and PH-1.13, showed different patterns for [symbol: see text]. The latter parameter was used to evaluate the helicity of this series of peptides. According to this parameter the relative helicity of this series is as follows: PH-1.12 > PH-1.0 > PH-1.4 > PH-1.19 > PH-1.13 The NMR data shown here correlated well with the helical propensities predicted for polypeptide sequences using statistical arguments (Proc. Natl. Acad. Sci. USA, 90, 9100, 1993).

9-(4-Hydroxybutyl)-N2-phenylguanine (HBPG), a thymidine kinase inhibitor, suppresses herpes virus reactivation in mice

In cells of the nervous system, which have little or no cellular thymidine kinase, the pharmacologic inhibition of viral thymidine kinase may prevent the reactivation of herpes virus, which requires phosphorylated thymidine for replication. We tested a newly synthesized inhibitor of viral thymidine kinase, 9-(4-hydroxybutyl)-N2-phenylguanine (HBPG) for its capacity to suppress the reactivation of herpes simplex virus type 1 (HSV-1) in vivo. Mice, latently infected with McKrae strain HSV-1, were treated with intraperitoneal injections of HBPG in a corn oil vehicle (200 mg/kg every 3 h for a total of ten doses), and subjected to hyperthermic stress to stimulate viral reactivation immediately before the third treatment. Three h after the last treatment, the mice were sacrificed, and the presence of infectious virus was determined by culture of ocular surface swabs and trigeminal ganglionic homogenates. Additionally, viral DNA in ganglionic extracts was analyzed by quantitative PCR. Controls included latently infected, stressed animals receiving injections of corn oil vehicle only, and latently infected, drug- and vehicle-treated, unstressed animals. HBPG had a statistically significant inhibitory effect on hyperthermia-induced viral reactivation. Homogenates of trigeminal ganglia and ocular surface swabs from HBPG-treated animals were less likely to contain infectious virus than those of infected, vehicle-treated, stressed controls (P < 0.005, ANOVA). Unstressed controls showed no reactivation. Quantitation of viral DNA in ganglionic extracts demonstrated a 100-fold reduction in the amount of viral DNA in the ganglia of HBPG-treated animals, compared with vehicle-treated controls (P < 0.05, ANOVA). The results indicate that HBPG has an inhibitory effect when given systemically for the suppression of herpes virus reactivation in mice.

Nucleotide probes of DNA polymerases

The modified nucleotides, N2-(p-n-butylphenyl)dGTP and 2-(p-n-butylanilino) dATP and related compounds have been developed as inhibitor-probes of B family DNA polymerases. Synthetic approaches to these compounds are summarized. The nucleotides are potent, non-substrate inhibitors of DNA polymerase a. In contrast, they inhibit other members of the family with less potency but act as substrates for these enzymes. Modelling of the inhibitor: enzyme binding mechanism has been done based on the known structure of E. coli DNA polymerase I, and site-directed mutagenesis experiments to evaluate this mechanism are proposed.

Specific and effective interaction of a guanine nucleotide analogue with small G proteins

G proteins are molecular switches that use a cycle of GTP binding and hydrolysis to regulate a wide variety of cellular biochemical processes. Because the functional state of these proteins is allosterically determined by bound guanine nucleotides, a nucleotide analogue with protein specificity might have pharmacological or biochemical value. The binding of [alpha-32P]GTP to four small G proteins immobilized on nitrocellulose was competed by a series of analogues with modifications at multiple sites. One analogue, N2-(p-n-butylphenyl)guanosine 5'-(beta,gamma-difluoromethylene)triphosphate, had a approximately 40-fold higher affinity for one small G protein than for two of the others. Systematic analysis of each modification in the synthetic nucleotide revealed that specificity was conferred by the carbon substitution in the beta,gamma-phosphoanhydride bond. These observations were then extended to purified proteins of known sequence in solution by filtration binding studies with H-ras and rab5. Ras was 9-fold more discriminant between guanosine-5'-(beta,gamma-difluoromethylene)triphosphate and guanosine-5'-O-(3-thiotriphosphate) than was rab5, and the Q79L GTPase-defective mutant of rab5 was 6-fold more discriminant than wild-type rab5. Guanosine-5'-(beta,gamma-difluoromethylene)triphosphate protected a 20-kDa fragment of rab5 from tryptic proteolysis with greater efficacy than guanosine-5'-O-(3-thiotriphosphate) or guanosine-5'-(beta,gamma-imido)triphosphate despite its lower affinity, and GMP stabilized a conformation indistinguishable from apo-rab5. These results identify a synthetic guanine nucleotide analogue with differential affinity for closely related G proteins, determine the atomic substitution in the analogue that confers specificity, demonstrate discrimination by the analogue between wild-type and a point-mutant G protein, and establish efficacy of the analogue in inducing conformational change of a target protein disproportionate to the affinity of the interaction.

Effects of stress management on clinical outcomes in rheumatoid arthritis

OBJECTIVE

To examine the effects of stress-management training on clinical outcomes in persons with rheumatoid arthritis (RA).

METHODS

Patients with RA (n = 141) were randomly assigned to 1 of 3 groups: a stress management group, an attention control group, or a standard care control group. The stress management and the attention control groups received a 10-week intervention followed by an additional 15-month maintenance phase.

RESULTS

The stress management group showed statistically significant improvements on measures of helplessness, self-efficacy, coping, pain, and health status. Selected beneficial effects were still detectable at the 15-month followup evaluation.

CONCLUSION

The data indicated that stress management interventions are capable of producing important clinical benefits for persons with RA.

The implications of depression for pain and disability in rheumatoid arthritis

Depression in rheumatoid arthritis (RA) affects many, but by no means all, persons with the disease. There is evidence that depression bears a significant relationship to pain in RA, although the causal direction is not entirely clear. Likewise, there is strong evidence that depression is a major contributor to the RA disability. Therefore, prevention, early diagnosis, and aggressive treatment of depression are needed to minimize the disability associated with RA.

Herpes simplex virus type 1 (HSV-1) uracil-DNA glycosylase: functional expression in Escherichia coli, biochemical characterization, and selective inhibition by 6-(p-n-octylanilino)uracil

The Herpes simplex virus type 1 (HSV-1) uracil-DNA glycosylase (UDG) is encoded by the UL2 gene. The translation from the first putative start codon of UL2 predicts a polypeptide of 334 residues, while the translation from the second start codon predicts a polypeptide of 244 residues. We have cloned and expressed the two forms of UDG, by means of the prokaryotic expression vector pMAL-c2, and both of them were enzymatically active. Furthermore, the enzymatic properties of the recombinant UDGs and of the enzyme purified from HSV-1-infected cells were similar. The two UDG polypeptides have molecular weights of 27 and 37 kDa, respectively. The 37-kDa form of recombinant UDG is consistent with the reported molecular mass of 37 kDa for the enzyme purified from HSV-1-infected cells. Both recombinant UDGs were as sensitive as UDG purified from HSV-1-infected cells to 6-(p-n-octylanilino)uracil, the most potent of a series of uracil analogs that inhibit the viral enzyme.

Inhibition of herpes simplex virus type 1 helicase-primase by (dichloroanilino)purines and -pyrimidines

Herpes simplex virus type 1 (HSV1) encodes a heterotrimeric helicase-primase comprised of the products of three of the seven DNA replication-specific genes. Several dihalo-substituted derivatives of N2-phenylguanines and 2-anilinoadenines weakly inhibited the intrinsic DNA-dependent NTPase activity of the HSV1 helicase-primase, and these compounds inhibited the DNA-unwinding activity of the enzyme. The primase activity of the enzyme was strongly inhibited by 3,4- and 3,5-dichloroanilino derivatives of adenine and 2-aminopyrimidines. These compounds and nucleoside analogs of 2-(3,5-dichloroanilino)purines inhibited viral DNA synthesis in HSV1-infected HeLa cells in culture but also inhibited cellular DNA synthesis, likely as a result of inhibition of cellular primase and/or DNA polymerases.

Haloanilino derivatives of pyrimidines, purines, and purine nucleoside analogs: synthesis and activity against human cytomegalovirus

2-Anilinopurines and 6-anilinopyrimidines bearing 3,4- or 3,5-dichloro substituents in the anilino ring inhibited virus-specific DNA synthesis by human cytomegalovirus (HCMV)-infected human embryonic lung (HEL) cells in culture. In general, active compounds had moderate to low selectivity for viral vs host cell DNA synthesis. Nucleoside and acyclonucleoside analogs of 2-(3,5-dichloroanilino)purines inhibited both HCMV and cellular DNA synthesis at similar concentrations. 2-Amino-4-chloro-6-(3,5-dichloroanilino)pyrimidine and several related compounds inhibited HCMV growth in yield reduction assays at concentrations that were nontoxic to HEL cells.

Synthesis, properties, and pharmacokinetic studies of N2-phenylguanine derivatives as inhibitors of herpes simplex virus thymidine kinases

Two series of selective inhibitors of herpes simplex virus types 1 and 2 (HSV1,2) thymidine kinases (TK) have been developed as potential treatment of recurrent virus infections. Among compounds related to the potent base analog N2-[m-(trifluoromethyl)phenyl]guanine (mCF3-PG), none was a more potent inhibitor than mCF3PG itself. Compounds related to the nucleoside N2-phenyl-2'-deoxyguanosine (PhdG), but with alkyl, hydroxyalkyl, and related substituents at the 9-position in place of the glycosyl group of PhdG, retained significant but variable inhibitory potencies against the HSV TKs. The most potent inhibitor of HSV1 TK among 9-substituted derivatives, 9-(4-hydroxybutyl)-N2-phenylguanine (HBPG), was a competitive inhibitor with respect to the substrate thymidine but was not itself a substrate for the enzyme. Water solubilities and 1-octanol:water partition coefficients for the 9-substituted N2-phenylguanines were linearly but oppositely related to the sum of hydrophobic fragmental constants (sigma f) of the 9-substituents. Four of the inhibitors were given as solutions to mice by iv and ip routes, and the time course of their plasma concentrations was determined by HPLC analysis of the parent compounds. HBPG was completely absorbed by the ip route, and the plasma concentration could be prolonged by use of suspension formulations. HBPG is a candidate for animal trials of the ability of TK inhibitors to prevent recurrent herpes virus infections.

Kinetic studies with N2-phenylguanines and with L-thymidine indicate that herpes simplex virus type-1 thymidine kinase and thymidylate kinase share a common active site

It is known that the Herpes simplex virus type 1 (HSV-1)-encoded thymidine kinase (TK) co-purifies with an associated thymidylate kinase (TMPK) activity and that thymidylate (TMP) inhibits the phosphorylation of thymidine by the HSV-1 TK. Here we demonstrate that: (i) TMP phosphorylation catalysed by the viral TMPK is competitively inhibited by thymidine (TdR) with a Ki equal to its Km as substrate for the viral TK; (ii) L-thymidine (L-TdR), the enantiomer of the naturally occurring D-TdR and a substrate for the HSV-1 TK [Spadari, Maga, Focher, Ciarrocchi, Manservigi, Arcamone, Capobianco, Caruso, Colonna, Iotti and Garbesi (1992) J. Med. Chem. 35, 4214-4220], is a powerful inhibitor of the HSV-1 TMPK activity with a Ki value identical with its Km as a substrate for the viral TK; (iii) both viral TK and TMPK activities are inhibited, in a competitive way and with identical Ki values, by novel, non-substrate inhibitors of HSV-1 TK, N2-phenylguanines; (iv) L-TdR is phosphorylated to L-TMP by the viral TK, but L-TMP is not phosphorylated to L-TDP by the viral TMPK activity; and (v) L-TMP inhibits competitively and with identical potencies the phosphorylation of TdR and TMP catalysed respectively by the HSV-1 TK and TMPK activities. In conclusion, our data demonstrate that both TK and TMPK activities encoded by HSV-1 share a common active site which is very tolerant in accepting modified nucleosides, but cannot readily accommodate modified nucleoside monophosphates.

Inhibitor analysis of calf thymus DNA polymerases alpha, delta and epsilon

Quantitative effects of inhibitors of the replicative DNA polymerases (pol) alpha, delta and epsilon from calf thymus are reported under similar assay conditions. Carbonyldiphosphonate was a competitive inhibitor of pols delta and epsilon, with 4- to 6-fold selectivity compared to pol alpha. Aphidicolin inhibited pols alpha and delta with 6- to 10-fold selectivity compared to pol epsilon. The 'butylphenyl' nucleotides, BuPdGTP and BuAdATP, inhibited pol alpha with at least 1000-fold selectivity compared to pols delta and epsilon. The use of these inhibitors under similar assay conditions permits the discrimination of the three enzymes.

Identification, partial purification and inhibition by guanine analogues of a novel enzymic activity which phosphorylates guanosine to GMP in the protozoan parasite Eimeria tenella

From oocysts of the protozoan parasite Eimeria tenella, responsible for avian coccidiosis, we have partially purified and characterized a novel enzymic activity which specifically phosphorylates guanosine to GMP. The enzyme is able to use several phosphate donors, in the order: acetyl phosphate (Ac-P) > ATP > UTP > CTP > phosphoribosyl pyrophosphate (PRPP) > dUTP > or = dATP. The low specificity of this enzyme for the phosphate donor suggested that it be named guanosine phosphotransferase (GPTase). This enzyme is biochemically distinct from the previously described adenosine kinase (AK) and hypoxanthine/xanthine/guanine phosphoribosyltransferase (HXGPRTase), and may enable the parasite to synthesize guanine nucleotides under conditions of imbalance between adenine and guanine nucleotides. Because of its possible role in the purine salvage pathways, we have studied the effect of several guanine and guanosine analogues, recently synthesized in our laboratory, on the activity of GPTase in vitro. GPTase is specifically inhibited in the micromolar range by several substituted N2-phenylguanine bases. These results indicate that, as previously found for AK and HXGPRTase, GPTase could be a potential target for antiparasitic chemotherapy.

Analysis of inhibitors of bacteriophage T4 DNA polymerase

Bacteriophage T4 DNA polymerase was inhibited by butylphenyl nucleotides, aphidicolin and pyrophosphate analogs, but with lower sensitivities than other members of the B family DNA polymerases. The nucleotides N2-(p-n-butylphenyl)dGTP (BuPdGTP) and 2-(p-n-butylanilino)dATP (BuAdATP) inhibited T4 DNA polymerase with competitive Ki values of 0.82 and 0.54 microM with respect to dGTP and dATP, respectively. The same compounds were more potent inhibitors in truncated assays lacking the competitor dNTP, displaying apparent Ki values of 0.001 and 0.0016 microM, respectively. BuPdGTP was a substrate for T4 DNA polymerase, and the resulting 3'-BuPdG-primer:template was bound strongly by the enzyme. Each of the non-substrate derivatives, BuPdGDP and BuPdGMPCH2PP, inhibited T4 DNA polymerase with similar potencies in both the truncated and variable competitor assays. These results indicate that BuPdGTP inhibits T4 DNA polymerase by distinct mechanisms depending upon the assay conditions. Reversible competitive inhibition predominates in the presence of dGTP, and incorporation in the absence of dGTP leads to potent inhibition by the modified primer:template. The implications of these findings for the use of these inhibitors in the study of B family DNA polymerases is discussed.

Herpes simplex virus type 1 uracil-DNA glycosylase: isolation and selective inhibition by novel uracil derivatives

We have purified Herpes simplex type 1 (HSV1) uracil-DNA glycosylase from the nuclei of HSV1-infected HeLa cells harvested 8 h post-infection, at which time the induction of the enzyme is a maximum. The enzyme has been shown to be distinct from the host enzyme, isolated from HeLa cells, by its lack of sensitivity to a monoclonal antibody to human uracil-DNA glycosylase. Furthermore, several uracil analogues were synthesized and screened for their capacity to discriminate between the viral and human uracil-DNA glycosylases. Both enzymes were inhibited by 6-(p-alkylanilino)uracils, but the viral enzyme was significantly more sensitive than the HeLa enzyme to most analogues. Substituents providing the best inhibitors of HSV1 uracil-DNA glycosylase were found to be in the order: p-n-butyl < p-n-pentl = p-n-hexyl < p-n-heptyl < p-n-octyl. The most potent HSV1 enzyme inhibitor, 6-(p-n-octylanilino)uracil (OctAU), with an IC50 of 8 microM, was highly selective for the viral enzyme. Short-term [3H]thymidine incorporation into the DNA of HeLa cells in culture was partially inhibited by OctAU, whereas it was unchanged when 6-(p-n-hexylanilino)uracil was present at concentrations that completely inhibited HSV1 uracil-DNA glycosylase activity. These compounds represent the first class of inhibitors that inhibit HSV1 uracil-DNA glycosylase at concentrations in the micromolar range. The results suggest their possible use to evaluate the functional role of HSV1 uracil-DNA glycosylase in viral infections and re-activation in nerve cells.

Chemical and enzymatic incorporation of N2-(p-n-butylphenyl)-2'-deoxyguanosine into an oligodeoxyribonucleotide

An 18mer oligodeoxyribonucleotide containing a N2-(p-n-butylphenyl)-2'-deoxyguanosine (BuPdG) residue at the 3' end has been synthesized by both chemical and enzymatic methods. Chemical synthesis involved attachment of 5'-DMT-BuPdG as the 3'-H-phosphonate to uridine-controlled pore glass (CPG), followed by extension via H-phosphonate chemistry. After oxidation of the backbone, deprotection of bases, and removal from CPG, the uridine residue was removed by periodate cleavage and beta-elimination. The resulting oligomer 3'-phosphate was digested with alkaline phosphatase to give the free BuPdG-18mer. E.coli DNA polymerase I (Klenow) incorporated BuPdGTP at the 3' end of the corresponding 17mer primer annealed to a complementary 29mer template, and the properties of this product were identical to those of chemically synthesized BuPdG-18mer. E.coli DNA polymerase I (Klenow) was unable to extend the BuPdG-18mer, and the 3' to 5' exonuclease activity of the enzyme was unable to remove the modified nucleotide.

Predicting hospital choice for rural Medicare beneficiaries: the role of severity of illness

Previous research has confirmed that desirable hospital attributes as well as increased distance, or travel time, have an impact on hospital choice. These studies have become increasingly sophisticated in modeling choice. This study adds to the existing literature by estimating the effect of both hospital and individual characteristics on hospital choice, using McFadden's conditional logit model. Some patient characteristics have not previously been accounted for in this type of analysis. In particular, the effect of a patient's complexity of illness (as measured by Disease Staging) on the choice of hospital is taken into account. The data consist of over 12,000 Medicare discharges in three overlapping rural market areas during 1986. The hospital choice set was aggregated into seven groups of urban and rural hospitals. Results indicate that rural Medicare beneficiaries tend to choose hospitals with a large scope of service and with teaching activity over those with a lower scope of service and no teaching activity, holding other factors constant. Distance is a deterrent to hospital choice, especially for older Medicare beneficiaries. The more complex cases tend to choose larger urban and rural hospitals over small rural hospitals more often than less complex cases do.

Sterility testing of antimicrobial-containing injectable solutions prepared in the pharmacy

The need for sterility testing of antimicrobial-containing injectable solutions is discussed and specific testing methods are described. Despite their antimicrobial activity, antimicrobial-containing injectable drug products are not necessarily self-sterilizing and can become contaminated. In addition to practicing aseptic technique, pharmacists must perform end-product sterility testing on intravenous solutions to ensure their sterility. The United States Pharmacopeia provides guidelines for the performance and validation of two sterility test methods: membrane filtration and direct transfer to culture media. Membrane filtration is the method of choice for sterility testing of many antimicrobial-containing injectable solutions. After the test article is filtered, the membrane is rinsed with sterile fluid to remove residual antimicrobial agent, cut into two portions, and immersed in two types of culture medium. Visible turbidity of a sample within the appropriate incubation period indicates the presence of a contaminating microorganism. Closed filtration systems minimize false-positive results. In the direct transfer method, samples of the test article are directly inoculated into vessels of culture media, and antimicrobial activity is eliminated by dilution or by deactivation with chemical or enzymatic agents. Sterility testing as well as aseptic technique is needed to ensure the sterility of antimicrobial-containing injectable solutions.

Photocatabolism of Aromatic Compounds by the Phototrophic Purple Bacterium Rhodomicrobium vannielii

The phototrophic purple non-sulfur bacterium Rhodomicrobium vannielii grew phototrophically (illuminated anaerobic conditions) on a variety of aromatic compounds (in the presence of CO 2 ). Benzoate was universally photocatabolized by all five strains of R. vannielii examined, and benzyl alcohol was photocatabolized by four of the five strains. Catabolism of benzyl alcohol by phototrophic bacteria has not been previously reported. Other aromatic substrates supporting reasonably good growth of R. vannielii strains were the methoxylated benzoate derivatives vanillate (4-hydroxy-3-methoxybenzoate) and syringate (4-hydroxy-3,5-dimethoxybenzoate). However, catabolism of vanillate and syringate led to significant inhibition of bacteriochlorophyll synthesis in R. vannielii cells, eventually causing cultures to cease growing. No such effect on photopigment synthesis in cells grown on benzoate or benzyl alcohol was observed. Along with a handful of other species of anoxygenic phototrophic bacteria, the ability of the species R. vannielii to photocatabolize aromatic compounds indicates that this organism may also be ecologically significant as a consumer of aromatic derivatives in illuminated anaerobic habitats in nature.