Biomedical subjects

K Barnhart

Publications and source records attributed to K Barnhart.

23 records · Page 2Linked to original sources

PubMed1995

Attitudes and practice of couples regarding sexual relations during the menses and spotting.

To determine attitudes and practices regarding sexual relations during menstruation and vaginal spotting, a cross-sectional descriptive survey was performed at the Instituto de Investigaciones Materno Infantil, Universidad de Chile, Santiago, Chile. A total of 287 women and 206 men were randomly selected from an urban population. Attitudes, beliefs, and practices regarding sexual relations during vaginal bleeding were surveyed and stratified by educational level and other demographic characteristics. Overall, 70% of women and 72% of men were found to avoid sexual relations during menstruation. Fifty-four percent of women and 60% of men avoided sexual relations during vaginal spotting. Women with higher education (technical or university) were less likely to avoid sexual intercourse compared to those with a lower educational level (basic or secondary education) during menstruation (73% vs. 57%) and vaginal spotting (69% vs. 34%). Men with a higher educational level (university) avoided intercourse less frequently when their partner was spotting (48% vs. 64%). As many methods of contraception affect a woman's menstrual cycle, they therefore may affect the intimacy of a couple. Counseling and education regarding the menstrual cycle and expected alterations by a contraceptive method may reduce any negative impact of a contraceptive device on a couple's sexual life.

Adult↗

PubMed1994

Prompt diagnosis of ectopic pregnancy in an emergency department setting.

OBJECTIVE: To evaluate quantitative hCG measurements and transvaginal ultrasound in the diagnosis of ectopic pregnancy in patients presenting to the emergency department. METHODS: A discriminatory zone for detecting the presence or absence of an intrauterine pregnancy by transvaginal ultrasound was established prospectively. Women presenting to the emergency department were evaluated prospectively using a diagnostic algorithm consisting of clinical examination, quantitative serum hCG, and transvaginal ultrasound. Finally, ectopic pregnancies diagnosed over a 22-month period were evaluated prospectively. RESULTS: All viable intrauterine pregnancies were identified in those subjects with hCG levels of 1500 mIU/mL (First International Reference) or greater. One thousand two hundred sixty-three subjects were evaluated prospectively; 59.8% were diagnosed with intrauterine pregnancy, 26.8% with spontaneous abortion, and 7.8% with ectopic pregnancy. At presentation, 13.2% of intrauterine pregnancies were diagnosed by clinical examination, whereas 82.9% were diagnosed by transvaginal ultrasound. Only 4% of normal intrauterine pregnancies were not confirmed on initial visit. Of 205 ectopic pregnancies diagnosed, 81.5% were hemodynamically stable; of these, 49.1% were diagnosed on initial presentation. Of all ectopics, 59% never reached an hCG level of 1500 mIU/mL and 35.8% had an hCG lower than the level at presentation. This protocol diagnosed ectopic pregnancies with a sensitivity of 100% and a specificity of 99.9%. CONCLUSION: A protocol of quantitative hCG levels (available within hours of presentation to an emergency department) combined with transvaginal ultrasound is effective in diagnosing ectopic pregnancy.

Chorionic Gonadotropin↗

PubMed1993

Increased frequency of obstructive airway abnormalities with long-term tracheostomy.

Eighty-one patients with long-term tracheostomy tubes (mean duration, 4.9 months) were examined via fiberoptic bronchoscopy prior to decannulation. Obstructive airway lesions were observed in 54 patients (67 percent). All tracheal lesions were anatomically located proximal to the stoma. No cuff lesions were observed. The two most commonly observed lesions were tracheal granuloma (60 percent) and tracheomalacia (29 percent). Less frequently observed lesions were tracheostenosis (14 percent) and vocal cord and laryngeal dysfunction (8 percent). As a result of the high frequency of tracheal abnormalities, especially that for tracheal granuloma which has not been previously reported (to our knowledge), we recommend that all decannulation candidates undergo anatomic examination of the airways.

Adult↗

PubMed1991

Site-specific 1,N6-ethenoadenylated single-stranded oligonucleotides as structural probes for the T4 gene 32 protein-ssDNA complex.

Bacteriophage T4 gene 32 protein (g32P) is a DNA replication accessory protein that binds single-stranded (ss) nucleic acids nonspecifically, independent of nucleotide sequence. G32P contains 1 mol of Zn(II)/mol of protein monomer, which can be substituted with Co(II), with maintenance of the structure and activity of the molecule. The Co(II) is coordinated via approximately tetrahedral ligand symmetry by three Cys sulfur atoms and therefore exhibits intense S(-)----Co(II) ligand to metal charge-transfer (LMCT) transitions in the near ultraviolet [Giedroc, D. P., et al. (1986) Proc. Natl. Acad. Sci. U.S.A. 83, 8452-8456]. A series of fluorescent 1,N6-ethenoadenosine (epsilon A)-containing oligonucleotides conforming to the structure (5'----3') d[(Tp)m epsilon A(pT)l-m-1] where 0 less than or equal to m less than or equal to l - 1 and length (l) six or eight nucleotides have been evaluated as dynamics probes and potential fluorescence energy transfer donors to Co(II) in mapping the spatial proximity of the (fixed) intrinsic metal ion and a variably positioned epsilon A-base in a series of protein-nucleic acid complexes. We provide spectroscopic evidence that the epsilon A-oligonucleotides bind to g32P-(A + B) with a fixed polarity of the phosphodiester chain. A Trp side chain(s) makes close approach to a epsilon A base positioned toward the 3' end of a bound l = 8 oligonucleotide. Six oligonucleotides of l = 8 and m = 0, 1, 3, 5, 6, or 7 were investigated as energy transfer donors to Co(II) at 0.1 M NaCl, pH 8.1, 25 degrees C upon binding to Co(II)-substituted or Zn(II) g32P-(A + B), i.e., in the presence and absence of an energy acceptor, respectively. Detectable quenching of the epsilon A-fluorescence by the Co(II)-LMCT acceptors was found to occur in all epsilon A-oligonucleotide-protein complexes, yielding energy transfer efficiencies (E) of 0.43, 0.31, 0.26, 0.26, 0.28, and 0.41 for l = 8 and m = 0, 1, 3, 5, 6, and 7 epsilon A-oligonucleotides, respectively. The two-dimensional distances R (in A) were found to vary as follows: d[epsilon A(pT)7] (m = 0), 16.0 (15.5-16.9); d[Tp epsilon A(pT)6] (m = 1), 17.7 (16.9-19.1); d[(Tp)3 epsilon A(pT)4] (m = 3), 20.7 (19.5-22.1); d[(Tp)5 epsilon A(pT)2] (m = 5), 20.5 (19.5-21.9); d[(Tp)6 epsilon ApT] (m = 6), 19.0 (18.0-20.4); and d[(Tp)7 epsilon A] (m = 7), 18.6 (17.8-19.8).(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine↗

PubMed1990

Overexpression, purification, and characterization of recombinant T4 gene 32 protein22-301 (g32P-B).

Gene 32 protein (g32P), the replication accessory protein from bacteriophage T4, is a zinc metalloprotein which binds with high cooperativity to single-stranded (ss) nucleic acids. The basic N-terminal 21 amino acids (termed the "B" domain) is required for highly cooperative (omega approximately 500) binding of g32P monomers to ss nucleic acids. As part of our studies to systematically evaluate the structural features of the B domain important for cooperative binding, a homogeneous source of g32P which binds noncooperatively to nucleic acids (omega = 1) and is devoid of contamination by native g32P is needed. Herein, we describe large-scale overexpression and purification of recombinant g32P lacking the tryptic N-terminal B domain (residues 1-21), designated g32P-B, as well as its physiochemical and nucleic acid binding properties. G32P-B is readily purified from the soluble fraction of Escherichia coli BL21 (DE3) transformed with the plasmid pT7g32-B.wt which contains the g32P-B coding sequences under inducible transcriptional control of T7 RNA polymerase. Anion exchange, ssDNA-cellulose and phenyl-Sepharose chromatographies give rise to highly homogeneous g32P-B, free of contaminating nucleic acid. Recombinant g32P-B has the expected N-terminal primary structure and contains stoichiometric Zn(II). It also has the expected globular structure as shown by 1H NMR spectroscopy, hydrodynamic measurements, and the ability to selectively remove the carboxyl-terminal "A" domain to form the trypsin-resistant g32P-(A + B) DNA-binding core fragment. Quantitative ss nucleic acid binding experiments of g32P-B to poly(dT) (0.05 M NaCl, pH 8.1, 20 degrees C) show that all equilibrium binding isotherms can be fit with omega = 1 and Kobs = 5.2 (+/- 1.6) x 10(5) M-1, with a moderate electrostatic component to the binding free energy, delta log Kobs/delta log[NaCl] = -3.0 +/- 0.2. Under identical solution conditions, g32P-(A + B) derived from g32P-B binds to poly(dT) noncooperatively as expected, but with an approximately 80-fold higher apparent affinity, Kobs = 4.0 (+/- 2.0) x 10(7) M-1, and detectable enhanced salt sensitivity, delta log Kobs/delta log[NaCl] = -3.9 +/- 0.3. As the salt concentration is raised, the relative difference in Kobs between the g32P-(A + B) and g32P-B is gradually reduced such that extrapolation of the log-log plots to 1 M Na+ standard state gives similar Kobs within experimental error. Qualitatively similar observations are also found upon binding to the ribohomopolymer, poly(U).(ABSTRACT TRUNCATED AT 400 WORDS)

Chromatography, Gel↗