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Biomedical subjects

M K Oh

Publications and source records attributed to M K Oh.

At least 37 records · Page 2Linked to original sources
PubMed2000

Health care service use and sexual communication: past experience and future intention of high-risk male adolescents.

High-risk male adolescents were surveyed to collect data to be used to develop strategies to enhance communication with their partners about sexually transmitted diseases (STDs). Participants were concerned about acquiring an STD from their partner, and reported an increased likelihood of communicating about STD-related issues when confidential health care was available.

Adolescent↗
PubMed2000

Opportunistic urine ligase chain reaction screening for sexually transmitted diseases in adolescents seeking care in an urban emergency department.

STUDY OBJECTIVE: Neisseria gonorrhoeae and Chlamydia trachomatis are the most common bacterial sexually transmitted diseases (STDs) in sexually active youth and many infections are asymptomatic or unrecognized. This study used ligase chain reaction assays for determination of prevalence of gonococcal and chlamydial infections in adolescents seeking care at an urban emergency department. METHODS: An unlinked prevalence study was performed with ligase chain reaction tests on voided urine specimens from a convenience sample of adolescents 14 years or older who sought care at the Children's Hospital of Alabama ED. Demographic data and data on care provided in the ED were determined from retrospective chart review of those patients whose urine specimens were tested. RESULTS: Of 282 urine specimens screened, 13.5% (38) yielded positive findings on ligase chain reaction testing for either or both pathogens (20 [7%] positive for N gonorrhoeae, 23 [8%] positive for C trachomatis). In the context of acute care, gonorrhea or chlamydial infection was diagnosed in 5 (1.8%). STD prevalence did not vary significantly by age. Only 39% (15/38) of patients with infections detected by ligase chain reaction testing received potentially effective antibiotics as a result of their urgent care evaluation. CONCLUSION: Many adolescents use the ED for nonurgent care and unsuspected STDs are often missed. Urine ligase chain reaction testing is a sensitive, noninvasive means of detecting STDs by which unsuspected adolescent STD cases can be detected in an ED setting.

Adolescent↗
PubMed2000

High prevalence of asymptomatic STDs in incarcerated minority male youth: a case for screening.

BACKGROUND AND OBJECTIVES: To assess STD prevalence among a sample of incarcerated minority male youth in a southern US city. METHODS: A consecutive entrant, cross-sectional study of 284 minority males 14 to 18 years was performed. All adolescents were screened for gonorrhea and chlamydia using ligase chain reaction tests. RESULTS: Eighteen percent of youth were identified as having either gonorrhea, chlamydia, or both. Approximately 84% of those with sexually transmitted diseases (STDs) self-reported having no symptoms. Failure to use condoms in the past month was significantly associated with a positive test result for STDs (odds ratio = 1.9, 95% CI = 1.1-3.3). CONCLUSIONS: The findings indicate an urgent need for routine STD screening and STD-prevention programs for adolescent males in detention facilities. A study of 284 detained black male adolescents revealed 18% prevalence of gonorrhea, chlamydia, or both. Approximately 84% of those with sexually transmitted diseases self-reported not having symptoms.

Adolescent↗
PubMed1999

Engineered isoprenoid pathway enhances astaxanthin production in Escherichia coli.

The isoprenoid pathway is a versatile biosynthetic network leading to over 23,000 compounds. Similar to other biosynthetic pathways, the production of isoprenoids in microorganisms is controlled by the supply of precursors, among other factors. To engineer a host that has the capability to supply geranylgeranyl diphosphate (GGPP), a common precursor of isoprenoids, we cloned and overexpressed isopentenyl diphosphate (IPP) isomerase (encoded by idi) from Escherichia coli and GGPP synthase (encoded by gps) from the archaebacterium Archaeoglobus fulgidus. The latter was shown to be a multifunctional enzyme converting dimethylallyl diphosphate (DMAPP) to GGPP. These two genes and the gene cluster (crtBIYZW) of the marine bacterium Agrobacterium aurantiacum were introduced into E. coli to produce astaxanthin, an orange pigment and antioxidant. This metabolically engineered strain produces astaxanthin 50 times higher than values reported before. To determine the rate-controlling steps in GGPP production, the IDI-GPS pathway was compared with another construct containing idi, ispA (encoding farnesyl diphosphate (FPP) synthase in E. coli), and crtE (encoding GGPP synthase from Erwinia uredovora). Results show that the conversion from FPP to GGPP is the first bottleneck, followed sequentially by IPP isomerization and FPP synthesis. Removal of these bottlenecks results in an E. coli strain providing sufficient precursors for in vivo synthesis of isoprenoids.

Alkyl and Aryl Transferases↗
PubMed1999

Toward predicting metabolic fluxes in metabolically engineered strains.

Predicting metabolic fluxes of a genetically engineered organism is an important step toward rational pathway design. However, because of various regulatory mechanisms, which are complex, often ill-characterized, and sometimes undiscovered, predicting metabolic fluxes using kinetic simulation is difficult. We propose to incorporate regulatory constraints in flux calculation to allow prediction of the steady-state fluxes without complete kinetics. The regulatory constraint, in its linear form, is derived from the dynamic metabolic control theory and involves the flux control coefficients. It is shown that with these constraints, the responses to metabolic perturbation can be predicted. Conversely, the regulatory constraints and the control coefficients can be determined by comparing the experimental data with the prediction. Therefore, this approach may offer a practical direction toward prediction of fluxes for metabolically engineered organisms.

Bioreactors↗
PubMed1998

Urine-based screening of adolescents in detention to guide treatment for gonococcal and chlamydial infections. Translating research into intervention.

OBJECTIVES: To determine the utility of urine-based ligase chain reaction assays for Neisseria gonorrhoeae and Chlamydia trachomatis in (1) the acceptability of such testing to adolescent detainees, (2) the potential use of these tests for identifying asymptomatic infections, and (3) the effectiveness of this approach for ensuring treatment of infected adolescents. DESIGN: Cross-sectional screening and verification of treatment for infected cases. SUBJECTS: Adolescents admitted to a short-term juvenile detention center. MAIN OUTCOME MEASURES: Neisseria gonorrhoeae and C trachomatis infection rates, and timing and location of treatment for infected patients. RESULTS: Refusal rate was 1.5%. Of 263 participants, 46 (17.5%) were female subjects. Chlamydia trachomatis infections were identified in 28.3% of the female and 8.8% of the male subjects. Neisseria gonorrhoeae infections were present in 13.1% of the female and 2.8% of the male subjects. Overall, 37 participants (14%) were positive for N gonorrhoeae, C trachomatis, or both, only one of whom had symptoms. Almost 70% (25/36) of asymptomatic infected subjects were treated within 28 days of screening. A treatment was documented in 36 of the 37 infected youth, including 20 who were followed up and treated after release from the detention center, by 6 months after testing. CONCLUSION: Urine ligase chain reaction tests were effective for identifying and guiding treatment of unsuspected N gonorrhoeae and C trachomatis infections in teenagers admitted to a short-term detention center where traditional swab specimens may be difficult to obtain.

Adolescent↗
PubMed1998

Medical status of adolescents at time of admission to a juvenile detention center.

PURPOSE: To examine the medical status and history of health care utilization of adolescents at the time of their admission to a juvenile detention facility. METHODS: Data were collected over an 18-month period on all detainees admitted for the first time to a juvenile detention facility in a major southeastern city in the United States. Information was gathered through a private, confidential interview completed by a medical social worker and a physical examination by a physician. Information was obtained regarding past medical history, complaints at the time of admission, health care utilization, and physical examination. RESULTS: Approximately 10% of teenagers admitted to a detention facility have a significant medical problem (excluding drug/alcohol abuse, or uncomplicated sexually transmitted diseases) that requires medical follow-up. The majority of these conditions were known to the adolescent at the time of admission. Only a third of adolescents admitted to the detention facility reported a regular source of medical care, and only about 20% reported having a private physician. A majority of all the detainees had already fallen behind in or dropped out of school. More than half of the families of the adolescents with a medical problem appeared to be unable or unwilling to assist in ensuring proper medical follow-up. CONCLUSIONS: A significant percentage of adolescents entering a detention facility have a medical problem requiring health care services. Detention facilities offer an opportunity to deliver and coordinate medical care to high-risk adolescents. Programs linking public and private health care providers with the correctional care system may provide juveniles with an acceptable option for obtaining needed health care services.

Adolescent↗
PubMed1997

Procreative experiences and orientations toward paternity held by incarcerated adolescent males.

PURPOSE: To describe the procreative experiences and the attitudes related to paternity held by a sample of incarcerated adolescent males. METHODS: All adolescent males who were admitted to a long-term correctional facility between July 1994 and October 1994 were asked to participate in a confidential, face-to-face interview. RESULTS: One hundred twenty-five incarcerated adolescents agreed to participate in the study. Over one-quarter (25.6%) of the respondents reported having ever gotten a girl pregnant; 40.6% of fathers reported having caused more than one pregnancy. A majority of respondents believed that fathering a child would be desirable, that they would be capable of being a father to a child, and that they could be responsible for the baby and mother. Fathers were more likely than nonfathers and black respondents were more likely than white respondents to report that they, their parents, and their friends would be pleased were they to get girls pregnant. Black respondents were more likely than white respondents to believe that they could be a good father to a child. CONCLUSIONS: The general perceptions that fathering a child as a teenager is desirable and that they could be good fathers to their children will make the prevention of pregnancy and parenting difficult in this population. Incarcerated adolescents should be educated about parenting prevention using interventions that take into consideration their attitudes and perceptions of teenage parenting.

Adolescent↗
PubMed1997

High prevalence of Chlamydia trachomatis infections in adolescent females not having pelvic examinations: utility of PCR-based urine screening in urban adolescent clinic setting.

PURPOSE: To determine utility of polymerase chain reaction (PCR)-based urine screening for Chlamydia trachomatis in the care of adolescent females in an urban clinic. METHODS: Females > or = 15 years of age attending an adolescent clinic were approached consecutively. Each enrollee was interviewed to determine the primary reason(s) for the clinic visit and was queried about genitourinary symptoms. Nonsterile voided urine specimens were tested for C. trachomatis using PCR-based analysis. Endocervical C. trachomatis cultures were obtained from the subjects who had a pelvic examination. Main outcome measures were chlamydia infection rates in clinic attendees whether a pelvic examination was performed or not. RESULTS: A total of 315 (99.4%) of 317 patients approached agreed to participate. Overall, 47 (14.9%) patients had positive urine PCR tests. The chlamydia infection rate detected by urine PCR was 22.1% (19 of 86) among those who had pelvic examinations performed and 12.2% (28 of 229) among those who did not (p = .03; odds ratio 2.04; 95% confidence interval 1.02, 4.06). Sixty percent (28 of 47) of chlamydia infections identified during the study period were identified by the urine screening test. CONCLUSION: Urine screening was accepted by vast majority of female adolescents attending the clinic irrespective of reason for the clinic visit, and was highly effective in identifying unsuspected C. trachomatis infections, particularly among girls attending the clinic for reasons unrelated to reproductive health care and as an interim screening tool for adolescent family-planning clients.

Adolescent↗
PubMed1996

Sexual contact tracing outcome in adolescent chlamydial and gonococcal cervicitis cases.

BACKGROUND AND OBJECTIVE: Treatment of sex partners is an essential part of sexually transmitted diseases (STD) control. This study examined the efficacy of contact tracing via patient self-referral in gonococcal and chlamydial cervicitis cases among adolescents, compared with the effectiveness of provider-referral. STUDY DESIGN: Adolescent females with culture-proven chlamydial or gonococcal cervicitis were the study subjects. This cohort study was done in an urban non-STD clinic setting. The subjects chose either provider-notification or self-notification method to inform their sex partner(s) in 2 months preceding the interview date. RESULTS: Two hundred and sixty-five eligible subjects (91% African-American, 9% white) were identified. One hundred and ninety-eight sex contacts were reported by 165 (62%) cases; no contact was elicited in the remaining 100 (38%). The follow-up data revealed that 129/198 (66%) contacts were informed: 63 contacts by 61 index cases, 54 contacts of 47 cases by the case manager, 9 by both methods, and 3 by unspecified means. History of treatment was obtained in 54 contacts, including 37% (23/63) of patient-notified contacts and 50% (27/54) of provider-notified contacts; these 54 contacts constituted 42% of informed contacts, or 27% of all named contacts. The mean number of sexual contacts treated per index case was 0.58 (27/47) for the provider-referral groups and 0.38 (23/61) for the self-referral groups. Successful contact tracing was documented in 19.3% (51/265) of all index cases, resulting in treatment of 54 contacts. CONCLUSION: This study demonstrates the need for more effective partner treatment strategies in adolescent STD cases.

Adolescent↗
PubMed1996

Risk for gonococcal and chlamydial cervicitis in adolescent females: incidence and recurrence in a prospective cohort study.

PURPOSE: This study attempted to determine the incidence and risk for gonococcal and chlamydial cervicitis among sexually active urban adolescent females. METHODS: The study design is a prospective cohort study. A cohort of 216 sexually active females were followed with repeat sexually transmitted diseases screening for 12-24 months. Subjects positive on any retest (FU) were compared with those who remained negative on all FU. Subjects were interviewed for history and screened for endocervical gonococcal and chlamydial infection. RESULTS: The number of visits per patient ranged from 2 to 9 (median, 3). The initial Chlamydia trachomatis and Neisseria gonorrhoeae rates were 23.2 and 11.6%, respectively. The cumulative FU positive rates were 20.8% for C. trachomatis and 17.1% for N. gonorrhoeae. Although the initial gonococcal infection was a significant risk for a subsequent infection by C. trachomatis (p = .05) and N. gonorrhoeae (p = .001), the initial C. trachomatis status was not predictive of subsequent infections. The number of partners was not predictive of subsequent infections with either. In the entire study period, 86 patients had at least one episode of C. trachomatis and N. gonorrhoeae infection was confirmed in 52; 20 patients had recurrent cervicitis. During the study, 101 episodes of C. trachomatis and 68 episodes of N. gonorrhoeae infections were identified. Those with recurrent cervicitis (9.3%) were responsible for 33% of all cervicitis episodes identified during the study. CONCLUSIONS: Adolescents in our study were at high risk for cervicitis, particularly as a result of C. trachomatis. Risk for subsequent C. trachomatis cervicitis was the same among initially positive and negative groups. Our data underscore the importance of repeat screening for sexually transmitted infections and treatment of contacts of adolescent females.

Adolescent↗
PubMed1993

Single dose of azithromycin for the treatment of genital chlamydial infections in adolescents.

We compared a single 1 gm dose of azithromycin with the standard 7-day course of doxycycline for the treatment of uncomplicated chlamydial genital infection in sexually active adolescents. Seventy-three adolescents (65 female) with a cervical or urethral culture positive for Chlamydia trachomatis were enrolled in the study; 46 received azithromycin and 27 received doxycycline. Follow-up evaluations were done 1, 2, and 4 weeks after treatment with azithromycin or initiation of treatment with doxycycline. There were four treatment failures (8.7%) among the patients who received azithromycin and four in the doxycycline-treated group (14.8%); all were female. Six of these girls (three treated with azithromycin and three with doxycycline) gave histories of unprotected intercourse with an untreated partner and were probably reinfected. Almost half the patients were clinically symptom free. The clinical response rate for the remaining patients with symptoms was 97.4% at 4 weeks. Nineteen percent of the azithromycin-treated patients and 33.3% of those treated with doxycycline had mild to moderate drug-related side effects, which were predominantly gastrointestinal. We conclude that treatment with a single oral dose of azithromycin appears to be as safe and efficacious as a 7-day course of doxycycline for the treatment of uncomplicated genital chlamydial infection in adolescents.

Administration, Oral↗
PubMed1991

Cytomegalovirus infection in sexually active adolescents.

To determine whether cytomegalovirus (CMV) infection in teenage girls is related to sexual activity, 254 girls 12-18 years old (mean, 15.8) attending a contraceptive counseling clinic were studied. Participants were screened for Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis, and serum antibody to CMV was determined. Demographic and sexual history data were collected by interview. The mean number of lifetime sex partners was 2.2; 173 (68%) were seropositive. Race, greater than 3 years of sexual activity, and greater than 2 lifetime sex partners were significant risk factors for CMV infection (odds ratios [OR], 1.8-4.7; P less than .05). Using logistic regression analysis, a composite sexual activity variable was the most important risk factor for CMV infection (OR, 4.8; P = .003), followed by race (OR, 3.4; P = .004) and a sexually transmitted disease composite variable (OR, 2.4; P = .016). Sexual activity is an important risk factor for CMV infection in adolescent girls.

Adolescent↗
PubMed1989

Chlamydia trachomatis cervical infection and oral contraceptive use among adolescent girls.

This study examines the relationship between oral contraceptive use and Chlamydia trachomatis cervical infection in women less than 19 years of age. The clinical and epidemiologic data of 73 (19.4% prevalence rate) girls with chlamydial infection were analyzed, with special attention given to contraceptive use. The findings were compared with data from 303 girls who were chlamydia negative to assess the relationship between oral contraceptive use and C. trachomatis infection. Use of an oral contraceptive for 6 months or longer was associated with chlamydial infection (p = 0.005; odds ratio = 2.41; 95% confidence interval 1.53-3.29). Oral contraceptive use was not associated with an increased rate of Neisseria gonorrhoeae or Trichomonas vaginalis infection. Association of oral contraceptive use with chlamydial infection remained significant after adjustments were made for confounding variables in a logistic regression process (p = 0.013). This study suggests that oral contraceptive use may promote chlamydial infection of the cervix or enhance the detection of the C. trachomatis from the cervix in this population.

Adolescent↗
PubMed1988

Sexually transmitted diseases and sexual behavior in urban adolescent females attending a family planning clinic.

Specimens from the lower genital tract of 102 sexually active urban adolescent females were tested for the common sexually transmitted diseases (STDs). The results were correlated with concomitant clinical, demographic, and historic data. Forty-one percent (42/102) were infected with one or more of the following organisms: Chlamydia trachomatis (26/102), Trichomonas vaginalis (13/102), Neisseria gonorrhoeae (10/102), yeast (6/102), condyloma (5/102), and herpes simplex virus (1/44). Mixed infections were found in 13%. Fifty-nine percent were negative for any infectious agents. The presence of genitourinary symptoms were of no value in predicting an STD. The rate of positive physical findings was significantly higher in the STD-positive group than in the negative group (p = 0.03), but 28% of the STD-negative group had positive physical findings, and 50% of the STD-positive group had normal physical findings. A history of genitourinary complaints or presence of physical findings was not predictive of a positive STD culture. Oral contraceptive use of more than six months appears to be a risk factor for an STD. No other factors, including the number of sexual partners, were significantly correlated with the presence of an STD. This study supports the need for routine screening of sexually active urban adolescent girls for an STD.

Adolescent↗
PubMedDate not supplied

Gene expression profiling by DNA microarrays and metabolic fluxes in Escherichia coli.

DNA microarray technology was applied to detect differential transcription profiles of a subset of the Escherichia coli genome. A total of 111 E. coli genes, including those in central metabolism, key biosyntheses, and some regulatory functions, were cloned, amplified, and used as probes for detecting the level of transcripts. An E. coli strain was grown in glucose, acetate, and glycerol media, and the transcript levels of the selected genes were detected. Despite extensive studies on E. coli physiology, many new features were found in the regulation of these genes. For example, several genes were unexpectedly up-regulated, such as pps, ilvG, aroF, secA, and dsbA in acetate and asnA and asnB in glycerol, or down-regulated, such as ackA, pta, and adhE in acetate. These genes were regulated with no apparent reasons by unknown mechanisms. Meanwhile, many genes were regulated for apparent purposes but by unknown mechanisms. For example, the glucose transport genes (ptsHI, ptsG, crr) in both acetate and glycerol media were down-regulated, and the ppc, glycolytic, and biosynthetic genes in acetate were also down-regulated because of the reduced fluxes. However, their molecular mechanisms remain to be elucidated. Furthermore, a group of genes were regulated by known mechanisms, but the physiological roles of such regulation remain unclear. This group includes pckA and aspA, which are up-regulated in glycerol, and gnd and aspA, which are down- and up-regulated, respectively, in acetate. The DNA microarray technology demonstrated here is a powerful yet economical tool for characterizing gene regulation and will prove to be useful for strain improvement and bioprocess development.

Carbon↗
PubMedDate not supplied

Directed evolution of metabolically engineered Escherichia coli for carotenoid production.

We have previously introduced a reconstructed isoprenoid pathway into Escherichia coli that exhibits amplified biosynthetic flux to geranylgeranyl diphosphate (GGPP), a common isoprenoid precursor. It was shown that GGPP synthase is an important rate-controlling enzyme in this reconstructed isoprenoid pathway. In this investigation, we applied directed evolution to GGPP synthase from Archaeoglobus fulgidus to enable the enhanced production of carotenoids in metabolically engineered E. coli. Eight mutants were isolated, and the best one increased lycopene production by 100%. Among the mutants that were isolated, mutation points were clustered in four "hot regions". The "hottest" region is located in the sequence upstream of the coding region, which presumably improves the expression level of the enzyme. The other three are within the coding sequence and are believed to improve the enzyme-specific activity in E coli. These results demonstrate that modulating both enzymatic expression and specific activity are important for optimizing the metabolic flux distribution.

Base Sequence↗