Correlations of maternal buprenorphine dose, buprenorphine, and metabolite concentrations in meconium with neonatal outcomes.

For the first time, relationships among maternal buprenorphine dose, meconium buprenorphine and metabolite concentrations, and neonatal outcomes are reported. Free and total buprenorphine and norbuprenorphine, nicotine, opiates, cocaine, benzodiazepines, and metabolites were quantified in meconium from 10 infants born to women who had received buprenorphine during pregnancy. Neither cumulative nor total third-trimester maternal buprenorphine dose predicted meconium concentrations or neonatal outcomes. Total buprenorphine meconium concentrations and buprenorphine/norbuprenorphine ratios were significantly related to neonatal abstinence syndrome (NAS) scores >4. As free buprenorphine concentration and percentage free buprenorphine increased, head circumference decreased. Thrice-weekly urine tests for opiates, cocaine, and benzodiazepines and self-reported smoking data from the mother were compared with data from analysis of the meconium to estimate in utero exposure. Time of last drug use and frequency of use during the third trimester were important factors associated with drug-positive meconium specimens. The results suggest that buprenorphine and metabolite concentrations in the meconium may predict the onset and frequency of NAS.

Molecular dynamics study of a bilayer electron gas: single particle properties.

The single-particle dynamical properties of a strongly coupled, classical, symmetric electronic bilayer system have been investigated by molecular dynamics simulation. Results for the velocity correlation function, the single-particle scattering function, and their respective Fourier transforms have been calculated, and their behavior, as a function of the interlayer separation d, has been analyzed. The single-particle scattering function in particular, shows dramatic effects when the bilayer attains a staggered square lattice structure. This occurs when the interlayer separation is around 0.8a (a is the Wigner-Seitz radius), where our previous study showed a marked decrease in the diffusion coefficient.

Molecular dynamics study of diffusion in a bilayer electron gas.

Molecular dynamics simulations of strongly coupled, classical electronic bilayers, interacting through the Coulomb potential, have been produced and studied. Values of the plasma coupling parameter Gamma between 10 and 80 and interlayer separations d from 0.1 to 3.0, (in units of Wigner-Seitz radius), were considered. The simulation results were used to calculate the intralayer and interlayer pair correlation functions and self-diffusion of charged particles in this system. The variation of self-diffusion with Gamma and d has been analyzed, and it is found that for the largest value of Gamma, the diffusion coefficient does not increase monotonically with layer separation, but has a distinct minimum for values of d slightly less than 1.

Physical and functional interactions of human DNA polymerase eta with PCNA.

Human DNA polymerase eta (hPoleta) functions in the error-free replication of UV-damaged DNA, and mutations in hPoleta cause cancer-prone syndrome, the variant form of xeroderma pigmentosum. However, in spite of its key role in promoting replication through a variety of distorting DNA lesions, the manner by which hPoleta is targeted to the replication machinery stalled at a lesion site remains unknown. Here, we provide evidence for the physical interaction of hPoleta with proliferating cell nuclear antigen (PCNA) and show that mutations in the PCNA binding motif of hPoleta inactivate this interaction. PCNA, together with replication factor C and replication protein A, stimulates the DNA synthetic activity of hPoleta, and steady-state kinetic studies indicate that this stimulation accrues from an increase in the efficiency of nucleotide insertion resulting from a reduction in the apparent K(m) for the incoming nucleotide.

Structure of the catalytic core of S. cerevisiae DNA polymerase eta: implications for translesion DNA synthesis.

DNA polymerase eta is unique among eukaryotic polymerases in its proficient ability to replicate through a variety of distorting DNA lesions. We report here the crystal structure of the catalytic core of S. cerevisiae DNA polymerase eta, determined at 2.25A resolution. The structure reveals a novel polydactyl right hand-shaped molecule with a unique polymerase-associated domain. We identify the catalytic residues and show that the fingers and thumb domains are unusually small and stubby. In particular, the unexpected absence of helices "O" and "O1" in the fingers domain suggests that openness of the active site is the critical feature which enables DNA polymerase eta to replicate through DNA lesions such as a UV-induced cis-syn thymine-thymine dimer.

Fidelity and damage bypass ability of Schizosaccharomyces pombe Eso1 protein, comprised of DNA polymerase eta and sister chromatid cohesion protein Ctf7.

DNA polymerase eta (Poleta) functions in error-free bypass of ultraviolet light-induced DNA lesions, and mutational inactivation of Poleta in humans causes the cancer prone syndrome, the variant form of xeroderma pigmentosum (XPV). Both Saccharomyces cerevisiae and human Poleta efficiently insert two adenines opposite the two thymines of a cyclobutane pyrimidine dimer. Interestingly, in the fission yeast Schizosaccharomyces pombe, the eso1(+) encoded protein is comprised of two domains, wherein the NH(2) terminus is highly homologous to Poleta, and the COOH terminus is highly homologous to the S. cerevisiae Ctf7 protein which is essential for the establishment of sister chromatid cohesion during S phase. Here we characterize the DNA polymerase activity of S. pombe GST-Eso1 fusion protein and a truncated version containing only the Poleta domain. Both proteins exhibit a similar DNA polymerase activity with a low processivity, and steady-state kinetic analyses show that on undamaged DNA, both proteins misincorporate nucleotides with frequencies of approximately 10(-2) to 10(-3). We also examine the two proteins for their ability to replicate a cyclobutane pyrimidine dimer-containing DNA template and find that both proteins replicate through the lesion equally well. Thus, fusion with Ctf7 has no significant effect on the DNA replication or damage bypass properties of Poleta. The possible role of Ctf7 fusion with Poleta in the replication of Cohesin-bound DNA sequences is discussed.

Accuracy of lesion bypass by yeast and human DNA polymerase eta.

DNA polymerase eta (Pol eta) functions in the error-free bypass of UV-induced DNA lesions, and a defect in Pol eta in humans causes the cancer-prone syndrome, the variant form of xeroderma pigmentosum. Both yeast and human Pol eta replicate through a cis-syn thymine-thymine dimer (TT dimer) by inserting two As opposite the two Ts of the dimer. Pol eta, however, is a low-fidelity enzyme, and it misinserts nucleotides with a frequency of approximately 10(-2) to 10(-3) opposite the two Ts of the TT dimer as well as opposite the undamaged template bases. This low fidelity of nucleotide insertion seems to conflict with the role of Pol eta in the error-free bypass of UV lesions. To resolve this issue, we have examined the ability of human and yeast Pol eta to extend from paired and mispaired primer termini opposite a TT dimer by using steady-state kinetic assays. We find that Pol eta extends from mispaired primer termini on damaged and undamaged DNAs with a frequency of approximately 10(-2) to 10(-3) relative to paired primer termini. Thus, after the incorporation of an incorrect nucleotide, Pol eta would dissociate from the DNA rather than extend from the mispair. The resulting primer-terminal mispair then could be subject to proofreading by a 3'-->5' exonuclease. Replication through a TT dimer by Pol eta then would be more accurate than that predicted from the fidelity of nucleotide incorporation alone.

Role of DNA polymerase eta in the bypass of a (6-4) TT photoproduct.

UV light-induced DNA lesions block the normal replication machinery. Eukaryotic cells possess DNA polymerase eta (Poleta), which has the ability to replicate past a cis-syn thymine-thymine (TT) dimer efficiently and accurately, and mutations in human Poleta result in the cancer-prone syndrome, the variant form of xeroderma pigmentosum. Here, we test Poleta for its ability to bypass a (6-4) TT lesion which distorts the DNA helix to a much greater extent than a cis-syn TT dimer. Opposite the 3' T of a (6-4) TT photoproduct, both yeast and human Poleta preferentially insert a G residue, but they are unable to extend from the inserted nucleotide. DNA Polzeta, essential for UV induced mutagenesis, efficiently extends from the G residue inserted opposite the 3' T of the (6-4) TT lesion by Poleta, and Polzeta inserts the correct nucleotide A opposite the 5' T of the lesion. Thus, the efficient bypass of the (6-4) TT photoproduct is achieved by the combined action of Poleta and Polzeta, wherein Poleta inserts a nucleotide opposite the 3' T of the lesion and Polzeta extends from it. These biochemical observations are in concert with genetic studies in yeast indicating that mutations occur predominantly at the 3' T of the (6-4) TT photoproduct and that these mutations frequently exhibit a 3' T-->C change that would result from the insertion of a G opposite the 3' T of the (6-4) TT lesion.

Requirement of DNA polymerase eta for error-free bypass of UV-induced CC and TC photoproducts.

The yeast RAD30-encoded DNA polymerase eta (Poleta) bypasses a cis-syn thymine-thymine dimer efficiently and accurately. Human DNA polymerase eta functions similarly in the bypass of this lesion, and mutations in human Poleta result in the cancer prone syndrome, the variant form of xeroderma pigmentosum. UV light, however, also elicits the formation of cis-syn cyclobutane dimers and (6-4) photoproducts at 5'-CC-3' and 5'-TC-3' sites, and in both yeast and human DNA, UV-induced mutations occur primarily by 3' C to T transitions. Genetic studies presented here reveal a role for yeast Poleta in the error-free bypass of cyclobutane dimers and (6-4) photoproducts formed at CC and TC sites. Thus, by preventing UV mutagenesis at a wide spectrum of dipyrimidine sites, Poleta plays a pivotal role in minimizing the incidence of sunlight-induced skin cancers in humans.

Tamoxifen in the management of pseudoangiomatous stromal hyperplasia.

Pseudoangiomatous stromal hyperplasia (PASH) is a relatively uncommon histologic finding in breast specimens. The clinicopathologic spectrum of this disease entity can range from a focal nonsignificant microscopic finding to a dominant palpable breast mass. To confirm the diagnosis, a biopsy is required primarily to distinguish PASH from a low-grade angiosarcoma. The mammographic description of PASH is a round or ovoid, circumscribed or partially circumscribed mass. The sonographic feature is a hypoechoic mass. PASH is similar to a fibroadenoma in clinical and imaging features. Progressive breast enlargement associated with engorgement, cyclical breast pain, and burning sensation is of significant concern for some women. The management of the palpable mass and associated symptoms has included excisional biopsy, often leading to recurrent excisions and even mastectomy. This report documents an impressive response to tamoxifen in a patient with PASH presenting with breast enlargement, pain, and breast masses. To our knowledge, there are no reports on the use of tamoxifen or other selective estrogen receptor modulators in the management of this benign breast condition.

Buprenorphine and naloxone for heroin dependence.

The pharmacology of buprenorphine is unique because of its partial agonist profile at the mu-opioid receptor (ie, high affinity, low intrinsic activity and slow dissociation). This unique profile results in greater safety, less physical dependence, and greater flexibility in dose scheduling. Buprenorphine has been investigated in combination with the opioid antagonist, naloxone, with the goal of decreasing abuse, misuse, and diversion. When combined with naloxone in a sublingual tablet, buprenorphine has been shown to be effective 1) in retaining patients in treatment, 2) in reducing opioid use and craving, and 3) when dosed less-than-daily. The pharmacologic effects of buprenorphine are not altered by the addition of naloxone when administered to the population in an appropriate combination ratio. However, if taken intravenously by individuals dependent on short- or long-acting opioids a precipitated withdrawal syndrome is observed, which should reduce its abuse potential. This review discusses the rationale for development and evidence supporting the use of a buprenorphine/naloxone combination product. The buprenorphine/naloxone combination product should be considered for use in primary care office-based settings as a safe and effective treatment that is likely to increase the availability of agonist treatment for opioid dependence.

Localized pruritus: a presenting symptom of a spinal cord tumor in a child with features of neurofibromatosis.

Central nervous system (CNS) and spinal cord tumors are not uncommon in patients with neurofibromatosis (NF); however, it is impossible to select patients with NF who are at a particularly high risk. Localized pruritus may be a clue to the presence of a spinal cord or CNS tumor. This is the first report of an infant with features of NF, whose presenting symptom of a spinal cord tumor was localized symmetrical dermatomal itch. Moreover, we review the literature of localized pruritus in CNS and spinal cord tumors and peripheral nervous system conditions.

Efficient and accurate replication in the presence of 7,8-dihydro-8-oxoguanine by DNA polymerase eta.

Oxidative damage to DNA has been proposed to have a role in cancer and ageing. Oxygen-free radicals formed during normal aerobic cellular metabolism attack bases in DNA, and 7, 8-dihydro-8-oxoguanine (8-oxoG) is one of the adducts formed. Eukaryotic replicative DNA polymerases replicate DNA containing 8-oxoG by inserting an adenine opposite the lesion; consequently, 8-oxoG is highly mutagenic and causes G:C to T:A transversions. Genetic studies in yeast have indicated a role for mismatch repair in minimizing the incidence of these mutations. In Saccharomyces cerevisiae, deletion of OGG1, encoding a DNA glycosylase that functions in the removal of 8-oxoG when paired with C, causes an increase in the rate of G:C to T:A transversions. The ogg1Delta msh2Delta double mutant displays a higher rate of CAN1S to can1r forward mutations than the ogg1Delta or msh2Delta single mutants, and this enhanced mutagenesis is primarily due to G:C to T:A transversions. The gene RAD30 of S. cerevisiae encodes a DNA polymerase, Poleta, that efficiently replicates DNA containing a cis-syn thymine-thymine (T-T) dimer by inserting two adenines across from the dimer. In humans, mutations in the yeast RAD30 counterpart, POLH, cause the variant form of xeroderma pigmentosum (XP-V), and XP-V individuals suffer from a high incidence of sunlight-induced skin cancers. Here we show that yeast and human POLeta replicate DNA containing 8-oxoG efficiently and accurately by inserting a cytosine across from the lesion and by proficiently extending from this base pair. Consistent with these biochemical studies, a synergistic increase in the rate of spontaneous mutations occurs in the absence of POLeta in the yeast ogg1Delta mutant. Our results suggest an additional role for Poleta in the prevention of internal cancers in humans that would otherwise result from the mutagenic replication of 8-oxoG in DNA.

Bovine gingival lysate: a novel substrate for rapid diagnosis of autoimmune vesiculo-bullous diseases. A preliminary observation.

Immunoblot assays have been developed to characterize the autoantigens and to detect autoantibodies in muco-cutaneous autoimmune vesiculo-bullous diseases using different substrates. However the results have been inconsistent, because availability and standardization of different substrates has been a major problem. The aim of this study was to develop an immunoblot assay using bovine gingival lysate as substrate because it is easily and readily available as well as inexpensive. Sera from patients with different vesiculo-bullous diseases were studied. These included 25 patients with pemphigus vulgaris (PV), 8 with paraneoplastic pemphigus (PNP), 12 with pemphigus foliaceus (PF), 25 with bullous pemphigoid (BP), and 22 with cicatricial pemphigoid (CP). Serum samples from 40 normal human volunteers were also studied. The autoantibody titers were determined based on the binding pattern of each disease and compared to those obtained by routine indirect immunofluorescence (IIF). Our observations suggest that the titers from immunoblot assays were significantly higher than titers obtained by IIF (P<0.0001). When the autoantibody titers were compared using bovine gingival lysate and human epidermal lysate as substrate, statistically significant differences were not observed. The use of bovine gingival lysate as a substrate will facilitate the rapid and early serological diagnosis of patients with vesiculobullous diseases. It may also be of benefit to laboratory investigators studying these autoantibodies.

A one-year audit of topics and domains in the Journal of the American Medical Association and the New England Journal of Medicine.

BACKGROUND: The relative emphasis that major medical journals give to topic areas has a potential effect on priorities in patient care, policy decisions, and public awareness. We measured the distribution of topics in two journals, by disease categories and domains, over a calendar year. METHODS: All original investigations, reviews, editorials, and special articles published in 1998 by the Journal of the American Medical Association and the New England Journal of Medicine were classified by article type, disease category, and domain. The 12 domains ranged from basic science to health policy, and included primary and secondary prevention. RESULTS: The 1159 articles published in 1998 included 889 (77%) articles about specific diseases-590 falling within eight specialties-and 190 (16%) articles on generic topics. Eighty (7%) articles concerned the behaviors that cause disease. Primary prevention and screening were the subject of 71 (6%) and 29 (3%) articles, respectively. Most of these concerned uncommon issues in patient care. Although 27 (2%) articles dealt with essential health promotion (e.g., diet, exercise), and none included a study on how to help patients to exercise, stop smoking, or eat a healthy diet. In contrast, 451 (39%) articles concerned the diagnosis and treatment of patients with disease. CONCLUSIONS: The relative emphasis that journals gave to prevention during the sample period seems discordant with its importance to patients and public health. Potential explanations include poor volume and quality of submitted research and editorial concerns about importance and reader appeal.

Evidence for the involvement of nucleotide excision repair in the removal of abasic sites in yeast.

In eukaryotes, DNA damage induced by ultraviolet light and other agents which distort the helix is removed by nucleotide excision repair (NER) in a fragment approximately 25 to 30 nucleotides long. In humans, a deficiency in NER causes xeroderma pigmentosum (XP), characterized by extreme sensitivity to sunlight and a high incidence of skin cancers. Abasic (AP) sites are formed in DNA as a result of spontaneous base loss and from the action of DNA glycosylases involved in base excision repair. In Saccharomyces cerevisiae, AP sites are removed via the action of two class II AP endonucleases, Apn1 and Apn2. Here, we provide evidence for the involvement of NER in the removal of AP sites and show that NER competes with Apn1 and Apn2 in this repair process. Inactivation of NER in the apn1Delta or apn1Delta apn2Delta strain enhances sensitivity to the monofunctional alkylating agent methyl methanesulfonate and leads to further impairment in the cellular ability to remove AP sites. A deficiency in the repair of AP sites may contribute to the internal cancers and progressive neurodegeneration that occur in XP patients.

Sarcoidosis presenting as spiculated breast masses.

A 67-year-old woman sought medical treatment of cardiomyopathy, which had been diagnosed 2 years earlier; the causative factor was sarcoidosis. A screening mammogram revealed multiple spiculated masses in both breasts. A review of previous films obtained elsewhere showed that these masses had been increasing in prominence during the past 3 years. The patient had no visible axillary nodal abnormalities. Sarcoidosis was considered a diagnostic possibility, and a large-core needle biopsy was done with stereotactic guidance. The histological diagnosis was non-necrotizing granulomatous inflammation, consistent with sarcoidosis.

Fidelity of human DNA polymerase eta.

Xeroderma pigmentosum (XP) patients are highly sensitive to sunlight, and they suffer from a high incidence of skin cancers. The variant form of XP results from mutations in the hRAD30A gene, which encodes the DNA polymerase in humans, hPol(eta). Of the eukaryotic DNA polymerases, only human Pol(eta) and its yeast counterpart have the ability to replicate DNA containing a cis-syn thymine-thymine (T-T) dimer. Here we measure the fidelity of hPol(eta) on all four nondamaged template bases and at each thymine residue of a cis-syn T-T dimer. Opposite all four nondamaged template bases, hPol(eta) misincorporates nucleotides with a frequency of approximately 10(-2)-10(-3), and importantly, hPol(eta) synthesizes DNA opposite the T-T dimer with the same accuracy and efficiency as opposite the nondamaged DNA. The low fidelity of hPol(eta) may derive from a flexible active site that renders the enzyme more tolerant of geometric distortions in DNA and enables it to synthesize DNA past a T-T dimer.

Is cigarette smoking associated with impaired physical and mental functional status? An office-based survey of primary care patients.

OBJECTIVE: To examine the relationship between cigarette smoking and self-reported physical and mental functional status. DESIGN: Cross-sectional survey of 837 patients visiting 2 family-practice centers. Patients completed a self-administered survey about functional status, tobacco use, and demographic characteristics while waiting to be called back for their appointments. SETTING: An inner-city family practice clinic in Richmond, Virginia, and a more affluent suburban practice outside Washington, DC. MAIN OUTCOME MEASURES: Physical and mental functional status, as measured by the SF-36 (Medical Outcomes Trust, Boston, MA); current and former cigarette use; and demographic variables (age, gender, education, income). RESULTS: Among current smokers, self-reported functional status scores were significantly lower than those of nonsmokers in all SF-36 domains (p < or = 0.02), a pattern that was more dramatic for mental functional status domains (social function, vitality, emotional role limitations, mental health). In several SF-36 domains, a dose-response relationship between smoking and functional status was noted. After multivariate adjustment for demographic confounders and practice site, the statistical significance of these differences diminished considerably, but it remained significant for certain domains and for the overall difference across all domains (MANCOVA p = 0.017). CONCLUSIONS: Current smokers report lower functional status than nonsmokers, in physical and especially in mental domains. The meaning of this cross-sectional relationship is unclear without further longitudinal study. Smoking may be associated with other variables that have a causal role.