21 results on '"Joseph K. Hwang"'
Search Results
2. Cesarean delivery rates and indications in pregnancies complicated by diabetes
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Kelsey L W, Olerich, Vivienne L, Souter, Emily E, Fay, Ronit, Katz, and Joseph K, Hwang
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Pediatrics, Perinatology and Child Health ,Obstetrics and Gynecology - Abstract
Rates of pregestational (PGDM) and gestational diabetes (GDM), and their associated pregnancy complications, are rising. Pregnancies complicated by diabetes have increased cesarean delivery (CD) rates; however, there are limited data regarding the current rates of, and contributing factors to, these deliveries. The Robson Ten Group Classification System (TGCS) is a clinically relevant, standardized framework that can be used to evaluate and analyze cesarean rates. The objective of this study was to evaluate rates of, and indications for, intrapartum, unplanned CD among pregnancies complicated by diabetes, compared to normoglycemic (NG) pregnancies, in a large United States birth cohort.This retrospective cohort study used chart-abstracted data on births between 24 and 42 weeks' gestation at 17 hospitals that contributed to the Obstetrical Care Outcome Assessment Program database between 01/2016 and 03/2019. The CD rate for NG pregnancies, and pregnancies complicated by gestational and PGDM was calculated and compared using the Robson TGCS. The indications for intrapartum CD in patients with term, singleton, vertex gestations without a prior cesarean were then analyzed. Univariate and multivariate logistic regression models were used to compare the cesarean rate and indications for CD, between the diabetic groups and the NG group. Results were adjusted for maternal age, BMI, neonatal birth weight, and insurance status, as well as clustering by hospital.A total of 86,381 pregnant people were included in the study cohort. Of these 76,272 (88.3%) were NG, 8591 (9.9%) had GDM, and 1518 (1.8%) had PGDM. Compared to NG patients, overall cesarean rates were higher in patients with GDM (40.3% vs. 29.7%; aOR 1.25, 95%CI 1.18-1.31) and PGDM (60.0% vs. 29.7%; aOR 2.53, 95%CI 2.04-3.13). This finding remained true when the cohort was restricted to term, singleton, vertex laboring patients without a prior cesarean; compared to NG patients, the cesarean rate was higher in patients with GDM (17.4% vs. 12.2%, aOR 1.37, 95%CI 1.29-1.45) and PGDM (26.0% vs. 12.2%, aOR 2.55, 95%CI 2.00-3.25). The cesarean rate for fetal indications was similar in the GDM (5.7%) and NG (4.4%) groups, while those patients with PGDM had a significantly higher rate (10.4%; aOR 2.01, 95%CI 1.43-2.83). Similarly, the rate of cesarean for labor dystocia in patients with PGDM was significantly higher than in NG patients (16.9% vs. 7.0%, and aOR 2.28, 95%CI 1.66-3.13) while patients with GDM had an intermediate rate (10.6% vs. 7.0%, aOR 1.49, 95%CI 1.40-1.57).The CD rate is significantly higher in pregnancies complicated by diabetes, particularly pregestational, compared to NG pregnancies. Despite controlling for maternal factors and birth weight, pregnancies complicated by diabetes are more likely to undergo an unplanned intrapartum cesarean secondary to labor dystocia than their NG counterparts, but only pregnancies complicated by PGDM have an increased risk of cesarean for fetal indications. More research is needed to understand whether this higher cesarean rate is due to factors intrinsic to diabetes in laboring patients or is due to a difference in the way clinicians manage diabetics in labor.
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- 2022
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3. Disease severity, pregnancy outcomes, and maternal deaths among pregnant patients with severe acute respiratory syndrome coronavirus 2 infection in Washington State
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Valerie Larios, Timothy Mitchell, Vera Schulte, Nena Barnhart, Andrew Chang, Jasmine Rah, Rebecca Resnick, Erica M Lokken, Sarah Hendrickson, Sylvia M LaCourse, Catherine M. Albright, Jessica S. Sheng, Jeroen Vanderhoeven, Sharilyn Emhoff, Karen Archabald, Emily M. Huebner, Anne Erickson, Kristina M. Adams Waldorf, Lori Kelley, Stephen A. McCartney, Stephen Erickson, Rita J. Hsu, Brahm Coler, Carolyn R. Kline, Chad Thomas, Washington State Covid in Pregnancy Collaborative, Brittany Bergam, Christie L. Walker, G. Gray Taylor, Victoria Larios, Kristin Retzlaff, Benjamin J. S. al-Haddad, Alisa Kachikis, Nicole M Kretzer, Joseph K. Hwang, Shani Delaney, Bettina W. Paek, and Kimberly K. Ma
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Adult ,Washington ,medicine.medical_specialty ,coronavirus ,Rate ratio ,medicine.disease_cause ,Severity of Illness Index ,Cohort Studies ,03 medical and health sciences ,Young Adult ,0302 clinical medicine ,Pregnancy ,Internal medicine ,Obstetrics and Gynaecology ,Case fatality rate ,medicine ,Humans ,pneumonia ,case-fatality ,030212 general & internal medicine ,Coronavirus ,Retrospective Studies ,030219 obstetrics & reproductive medicine ,business.industry ,SARS-CoV-2 ,maternal mortality ,Mortality rate ,Original Research: Obstetrics ,Infant, Newborn ,Pregnancy Outcome ,Obstetrics and Gynecology ,COVID-19 ,preterm birth ,medicine.disease ,Comorbidity ,fetus ,Maternal Death ,Maternal death ,Female ,business ,Cohort study - Abstract
BACKGROUND: Evidence is accumulating that coronavirus disease 2019 increases the risk of hospitalization and mechanical ventilation in pregnant patients and for preterm delivery. However, the impact on maternal mortality and whether morbidity is differentially affected by disease severity at delivery and trimester of infection are unknown. OBJECTIVE: This study aimed to describe disease severity and outcomes of severe acute respiratory syndrome coronavirus 2 infections in pregnancy across the Washington State, including pregnancy complications and outcomes, hospitalization, and case fatality. STUDY DESIGN: Pregnant patients with a polymerase chain reaction-confirmed severe acute respiratory syndrome coronavirus 2 infection between March 1, 2020, and June 30, 2020, were identified in a multicenter retrospective cohort study from 35 sites in Washington State. Sites captured 61% of annual state deliveries. Case-fatality rates in pregnancy were compared with coronavirus disease 2019 fatality rates in similarly aged adults in Washington State using rate ratios and rate differences. Maternal and neonatal outcomes were compared by trimester of infection and disease severity at the time of delivery. RESULTS: The principal study findings were as follows: (1) among 240 pregnant patients in Washington State with severe acute respiratory syndrome coronavirus 2 infections, 1 in 11 developed severe or critical disease, 1 in 10 were hospitalized for coronavirus disease 2019, and 1 in 80 died; (2) the coronavirus disease 2019-associated hospitalization rate was 3.5-fold higher than in similarly aged adults in Washington State (10.0% vs 2.8%; rate ratio, 3.5; 95% confidence interval, 2.3-5.3); (3) pregnant patients hospitalized for a respiratory concern were more likely to have a comorbidity or underlying conditions including asthma, hypertension, type 2 diabetes mellitus, autoimmune disease, and class III obesity; (4) 3 maternal deaths (1.3%) were attributed to coronavirus disease 2019 for a maternal mortality rate of 1250 of 100,000 pregnancies (95% confidence interval, 257-3653); (5) the coronavirus disease 2019 case fatality in pregnancy was a significant 13.6-fold (95% confidence interval, 2.7-43.6) higher in pregnant patients than in similarly aged individuals in Washington State with an absolute difference in mortality rate of 1.2% (95% confidence interval, -0.3 to 2.6); and (6) preterm birth was significantly higher among women with severe or critical coronavirus disease 2019 at delivery than for women who had recovered from coronavirus disease 2019 (45.4% severe or critical coronavirus disease 2019 vs 5.2% mild coronavirus disease 2019; P
- Published
- 2020
4. 185 Cesarean section rates by induction of labor indication in diabetic pregnancies
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Kelsey Olerich, Emily E. Fay, and Joseph K. Hwang
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medicine.medical_specialty ,business.industry ,Obstetrics ,Section (typography) ,Obstetrics and Gynecology ,Medicine ,Induction of labor ,business - Published
- 2021
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5. Higher severe acute respiratory syndrome coronavirus 2 infection rate in pregnant patients
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Michela Blain, Catherine M. Albright, Chad Thomas, Kristin Retzlaff, Victoria Larios, Stephen A. McCartney, Sarah Hendrickson, Alisa Kachikis, Anne Erickson, Nicole M Kretzer, Valerie Larios, Sharilyn Emhoff, Joseph K. Hwang, Sylvia M LaCourse, Andrew Chang, Jasmine Rah, Lori Kelley, G. Gray Taylor, Bettina W. Paek, Shani Delaney, Rebecca Resnick, Jessica S. Sheng, Christie L. Walker, Kimberly K. Ma, Jeroen Vanderhoeven, Karen Archabald, Rebecca Gourley, Nena Barnhart, Carolyn R. Kline, Kristina M. Adams Waldorf, Emily M. Huebner, Stephen Erickson, Rita J. Hsu, Erica M Lokken, Vera Schulte, Timothy Mitchell, Brahm Coler, and Brittany Bergam
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education.field_of_study ,Pregnancy ,medicine.medical_specialty ,030219 obstetrics & reproductive medicine ,business.industry ,Obstetrics ,Public health ,Population ,Obstetrics and Gynecology ,Rate ratio ,medicine.disease ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Pacific islanders ,030212 general & internal medicine ,Young adult ,Risk factor ,education ,business ,Cohort study - Abstract
Background During the early months of the coronavirus disease of 2019 (COVID-19) pandemic, risks to pregnant women of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection were uncertain. Pregnant patients can serve as a model for the success of the clinical and public health response during public health emergencies as they are typically in frequent contact with the medical system. Population-based estimates of SARS-CoV-2 infections in pregnancy are unknown due to incomplete ascertainment of pregnancy status or inclusion of only single centers or hospitalized cases. Whether pregnant women were protected by the public health response or through their interactions with obstetrical providers in the early pandemic is poorly understood. Objective(s) To estimate the SARS-CoV-2 infection rate in pregnancy and examine disparities by race/ethnicity and English-language proficiency in Washington State. Study design Pregnant patients with a polymerase chain reaction (PCR)-confirmed severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection diagnosed between March 1-June 30, 2020 were identified within 35 hospitals/clinic systems capturing 61% of annual deliveries in Washington State. Infection rates in pregnancy were estimated overall and by Washington State Accountable Community of Health (ACH) region and cross-sectionally compared to SARS-CoV-2 infection rates in similarly aged adults in Washington State. Race/ethnicity and language used for medical care among the pregnant patients were compared to recent data from Washington State. Results A total of 240 pregnant patients with SARS-CoV-2 infections were identified during the study period with 70.7% from minority racial and ethnic groups. The principal findings in our study are: 1) The SARS-CoV-2 infection rate in pregnancy was 13.9/1,000 deliveries (95% confidence interval [CI], 8.3-23.2) compared to 7.3/1,000 (95%CI 7.2-7.4) in 20-39 year old adults in Washington State (Rate Ratio [RR] 1.7, 95%CI 1.3-2.3), 2) the SARS-CoV-2 infection rate reduced to 11.3/1000 (95%CI 6.3-20.3) when excluding 45 cases of SARS-CoV-2 detected through asymptomatic screening (RR 1.3, 95%CI 0.96-1.9), 3) the proportion of SARS-CoV-2 cases in pregnancy among most non-white racial/ethnic groups was 2-4 fold higher than the race and ethnicity distribution of women in Washington State who delivered live births in 2018, and 5) the proportion of SARS-CoV-2 infected pregnant patients receiving medical care in a non-English language was higher than estimates of limited English proficiency in Washington State (30.4% versus 7.6%). Conclusions The SARS-CoV-2 infection rate in pregnant people was 70% higher than similarly aged adults in Washington State, which could not be completely explained by universal screening at delivery. Pregnant patients from nearly all racial/ethnic minority groups and patients receiving medical care in a non-English language were overrepresented. Pregnant women were not protected from COVID-19 in the early months of the pandemic with the greatest burden of infections occurring in nearly all racial/ethnic minority groups. This data coupled with a broader recognition that pregnancy is a risk factor for severe illness and maternal mortality strongly suggests that pregnant people should be broadly prioritized for COVID-19 vaccine allocation in the U.S. similar to some states.
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- 2021
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6. 224: Cesarean birth rates in pregestational diabetic pregnancies
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Kristin Sitcov, Joseph K. Hwang, Kelsey Olerich, Vivienne Souter, Emily E. Fay, and Ian Painter
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medicine.medical_specialty ,Cesarean Birth ,Obstetrics ,business.industry ,medicine ,Obstetrics and Gynecology ,business - Published
- 2020
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7. Clinical characteristics of 46 pregnant women with a severe acute respiratory syndrome coronavirus 2 infection in Washington State
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Nena Barnhart, Sylvia M LaCourse, Shani Delaney, Michela Blain, Jessica S. Sheng, Chad Thomas, Christie L. Walker, Stephen A. McCartney, Kristin Retzlaff, Alisa Kachikis, Anne Erickson, Joseph K. Hwang, Nicole M Kretzer, Jeroen Vanderhoeven, Gail H. Deutsch, Bettina W. Paek, Kimberly K. Ma, Jasmine Rah, Rebecca Resnick, Emily M. Huebner, Carolyn R. Kline, Erica M Lokken, Jeff Munson, and Kristina M. Adams Waldorf
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Pregnancy ,Pediatrics ,medicine.medical_specialty ,business.industry ,Obstetrics and Gynecology ,Retrospective cohort study ,Disease ,Overweight ,medicine.disease ,Asymptomatic ,Intensive care unit ,law.invention ,law ,Obstetrics and Gynaecology ,medicine ,Etiology ,Maternal death ,medicine.symptom ,business - Abstract
Background The impact of the coronavirus disease 2019 (Covid-19) on pregnant women is incompletely understood, but early data from case series suggest a variable course of illness from asymptomatic or mild disease to maternal death. It is unclear whether pregnant women manifest enhanced disease similar to influenza viral infection or whether specific risk factors might predispose to severe disease. Objective To describe maternal disease and obstetrical outcomes associated with Covid-19 disease in pregnancy to rapidly inform clinical care. Study Design Retrospective study of pregnant patients with a laboratory-confirmed severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection from six hospital systems in Washington State between January 21, 2020 and April 17, 2020. Demographics, medical and obstetric history, and Covid-19 encounter data were abstracted from medical records. Results A total of 46 pregnant patients with a SARS-CoV-2 infection were identified from hospital systems capturing 40% of births in Washington State. Nearly all pregnant individuals with a SARS-CoV-2 infection were symptomatic (93.5%, n=43) and the majority were in their second or third trimester (43.5%, n=20 and 50.0%, n=23, respectively). Symptoms resolved in a median of 24 days (interquartile range 13-37). Seven women were hospitalized (16%) including one admitted to the intensive care unit. Six cases (15%) were categorized as severe Covid-19 disease with nearly all patients being either overweight or obese prior to pregnancy, asthma or other co-morbidities. Eight deliveries occurred during the study period, including a preterm birth at 33 weeks to improve pulmonary status in a woman with Class III obesity. One stillbirth occurred of unknown etiology. Conclusions Nearly 15% of pregnant patients developed severe Covid-19, which occurred primarily in overweight or obese women with underlying conditions. Obesity and Covid-19 may synergistically increase risk for a medically-indicated preterm birth to improve maternal pulmonary status in late pregnancy. Collectively, these findings support categorizing pregnant patients as a higher risk group, particularly for those with chronic co-morbidities.
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- 2020
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8. Is the Shirodkar a Better Technique for Ultrasound Indicated Cerclages? [9O]
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Gene Ta-Chung Lee, Jordan McColm, Kathryn Lindsay, Jennifer Brooks, and Joseph K. Hwang
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business.industry ,Ultrasound ,Obstetrics and Gynecology ,Medicine ,business ,Nuclear medicine - Published
- 2019
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9. Maternal microbiome - A pathway to preterm birth
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Indira U. Mysorekar, Angela E. Vinturache, Bo Jacobsson, Cynthia Gyamfi-Bannerman, and Joseph K. Hwang
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0301 basic medicine ,Placenta ,Cervix Uteri ,Bioinformatics ,03 medical and health sciences ,0302 clinical medicine ,Pregnancy ,Medicine ,Humans ,Microbiome ,Intestinal Mucosa ,Pregnancy outcomes ,Preterm delivery ,030219 obstetrics & reproductive medicine ,business.industry ,Microbiota ,Human microbiome ,Mouth Mucosa ,Infant mortality ,030104 developmental biology ,medicine.anatomical_structure ,Metagenomics ,Pediatrics, Perinatology and Child Health ,Immunology ,Vagina ,Dysbiosis ,Premature Birth ,Research questions ,Female ,business - Abstract
Despite great medical advances in preventing maternal and infant mortality in the past century, one issue remains unresolved: why do so many women give birth prematurely? A major new field of human microbiome studies has begun to shed light on the impact of microbes (of both the commensal and pathogen varieties) on pregnancy outcomes. Recent advances in next-generation sequencing and metagenomic analysis have revealed that maternal microbiomes at a variety of niches including the oral, vaginal, gut, cervical, and even the placenta itself govern pregnancy outcomes. In this review, we describe how alterations in the microbial biomasses impact preterm birth and we discuss the major research questions concerning the cause and/or interdependent relationships between microbiome, infection, and preterm delivery.
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- 2016
10. Sonographic prenatal diagnosis of congenital Marfan syndrome
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Joseph K. Hwang and Rachel M Bender
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musculoskeletal diseases ,Marfan syndrome ,congenital, hereditary, and neonatal diseases and abnormalities ,History ,Pediatrics ,medicine.medical_specialty ,business.industry ,Severe disease ,Prenatal diagnosis ,Limiting ,medicine.disease ,Computer Science Applications ,Education ,Surgery ,Prenatal screening ,Family planning ,Medicine ,Disease management (health) ,business ,De novo mutations - Abstract
Congenital Marfan syndrome is a rare and severe disease of the newborn, causing devastating and often fatal effects on the cardiovascular, pulmonary, and musculoskeletal systems. Familial mutations of FBN1 have been studied and identified in Marfan syndrome, but the congenital variant is often due to de novo mutations, limiting the diagnostic capabilities of genetic screening. Ultrasound is essential for early diagnosis and management, yet few cases of sonographic diagnosis have been cited in the literature. This report outlines one such case of congenital Marfan syndrome diagnosed at 24-week ultrasound. Further detailed reports should aim to improve screening, diagnosis, and treatment of congenital Marfan syndrome to advance options in family planning and disease management.
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- 2012
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11. Progenitor cell maintenance requires numb and numblike during mouse neurogenesis
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Yuh Nung Jan, Joseph K. Hwang, Kaiyong Zou, Weimin Zhong, and Pétur Henry Petersen
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Nervous system ,Time Factors ,Cellular differentiation ,Nerve Tissue Proteins ,Biology ,Nervous System ,Mice ,medicine ,Animals ,Drosophila Proteins ,Cell Lineage ,Progenitor cell ,Alleles ,Progenitor ,Mice, Knockout ,Motor Neurons ,Multidisciplinary ,Cell Death ,Stem Cells ,Neurogenesis ,Intracellular Signaling Peptides and Proteins ,Cell Differentiation ,Anatomy ,Neural stem cell ,Cell biology ,Juvenile Hormones ,medicine.anatomical_structure ,NUMB ,Stem cell ,Cell Division ,Gene Deletion - Abstract
Neurons in most regions of the mammalian nervous system are generated over an extended period of time during development. Maintaining sufficient numbers of progenitors over the course of neurogenesis is essential to ensure that neural cells are produced in correct numbers and diverse types. The underlying molecular mechanisms, like those governing stem-cell self-renewal in general, remain poorly understood. We report here that mouse numb and numblike (Nbl), two highly conserved homologues of Drosophila numb, play redundant but critical roles in maintaining neural progenitor cells during embryogenesis, by allowing their progenies to choose progenitor over neuronal fates. In Nbl mutant embryos also conditionally mutant for mouse numb in the nervous system, early neurons emerge in the expected spatial and temporal pattern, but at the expense of progenitor cells, leading to a nearly complete depletion of dividing cells shortly after the onset of neurogenesis. Our findings show that a shared molecular mechanism, with mouse Numb and Nbl as key components, governs the self-renewal of all neural progenitor cells, regardless of their lineage or regional identities.
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- 2002
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12. A recombinogenic targeting method to modify large-inserts for cis -regulatory analysis in transgenic mice: construction and expression of a 100-kb, zebrafish Hoxa-11b-lacZ reporter gene
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Janet L. Carr, Frank H. Ruddle, Joseph K. Hwang, Cooduvalli S. Shashikant, Jaya Bhargava, Chi-hua Chiu, Günter P. Wagner, and Chris T. Amemiya
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Homeodomain Proteins ,Regulation of gene expression ,Reporter gene ,biology ,Transgene ,Genetic Vectors ,DNA, Recombinant ,Gene Expression Regulation, Developmental ,Mice, Transgenic ,Zebrafish Proteins ,biology.organism_classification ,Molecular biology ,Mice ,Exon ,Lac Operon ,Shuttle vector ,Genes, Reporter ,Gene Targeting ,Gene expression ,Genetics ,Animals ,Gene ,Zebrafish ,Developmental Biology - Abstract
The identification of cis-sequences responsible for spatiotemporal patterns of gene expression often requires the functional analysis of large genomic regions. In this study a 100-kb zebrafish Hoxa-11b-lacZ reporter gene was constructed and expressed in transgenic mice. PAC clone 10-O19, containing a portion of the zebrafish HoxA-b cluster, was captured into the yeast-bacterial shuttle vector, pPAC-ResQ, by recombinogenic targeting. A lacZ reporter gene was then inserted in-frame into exon 1 of the zfHoxa-11b locus by a second round of recombinogenic targeting. Expression of the zfHoxa-11b-lacZ reporter gene in 10.5 d.p.f. transgenic mouse embryos was observed only in the posterior portion of the A-P axis, in the paraxial mesoderm, neural tube, and somites. These findings demonstrate the utility of recombinogenic targeting for the modification and expression of large inserts captured from P1/PAC clones.
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- 2000
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13. PSEUDOANEURYSM OF THE UTERINE ARTERY
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Joseph K. Hwang, A. Zimon, Ray O. Bahado-Singh, and David L. Principe
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Adult ,medicine.medical_specialty ,Duplex ultrasonography ,medicine.medical_treatment ,Pseudoaneurysm ,Aneurysm ,medicine.artery ,medicine ,Humans ,cardiovascular diseases ,Embolization ,Uterine artery ,Ultrasonography ,Pregnancy ,Vascular disease ,business.industry ,Uterus ,Obstetrics and Gynecology ,Puerperal Disorders ,medicine.disease ,Surgery ,Radiography ,cardiovascular system ,Suprapubic pain ,Female ,Radiology ,business ,Aneurysm, False - Abstract
Background: Preexisting aneurysms in several arterial locations have been associated with an increased risk of rupture in pregnancy. We report a rare case of uterine artery pseudoaneurysm that presented during the puerperium. Case: A 31-year-old woman had moderate suprapubic pain on postpartum day 8. The diagnosis of uterine artery aneurysm was made by duplex Doppler sonography and confirmed by arteriography. It was successfully treated by embolization of the left uterine artery. Conclusion: In a rare case of pseudoaneurysm of the uterine artery, the complications of pregnancy-related aneurysmal rupture were prevented by prompt sonographic diagnosis and embolization therapy.
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- 1999
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14. Carbon-13 and proton spin relaxation in methane in the gas phase
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Joseph K. Hwang, T. Zia, N.C. Smith, Cynthia J. Jameson, and A.K. Jameson
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Light nucleus ,Crystallography ,Virial coefficient ,Chemistry ,Carbon-13 ,General Engineering ,Angstrom ,Physical and Theoretical Chemistry ,Atomic physics ,Spin relaxation ,Gas phase - Abstract
The dominance of the spin-rotation mechanism in the relaxation of both the {sup 13}C and the {sup 1}H nuclear spins in {sup 13}CH{sub 4} in various buffer gases has been established. Cross sections for changes in the rotational angular momentum vector of CH{sub 4} molecules in collisions with various molecules have been obtained as a function of temperature from the measured spin relaxation times of {sup 13}C or {sup 1}H or both. At 300 K these cross sections are 18.8 {plus minus} 0.5 {angstrom}{sup 2} (CH{sub 4}-CH{sub 4}), 16.3 {plus minus} 0.3 {angstrom}{sup 2} (CH{sub 4}-N{sub 2}), 15.8 {plus minus} 0.2 {angstrom} (CH{sub 4}-CO), 24 {plus minus} 1 {angstrom}{sup 2} (CH{sub 4}-CO{sub 2}), 15 {plus minus} 1 {angstrom}{sup 2} (CH{sub 4}-Ar), 18.3 {plus minus} 0.6 {angstrom}{sup 2} (CH{sub 4}-Kr), 22.4 {plus minus} 0.2 {angstrom}{sup 2} (CH{sub 4}-Xe), 24 {plus minus} 1 {angstrom}{sup 2} (CH{sub 4}-HCl), 25 {plus minus} 1 {angstrom}{sup 2} (CH{sub 4}-CF{sub 4}), 34.5 {plus minus} 1.1 {angstrom}{sup 2} (CH{sub 4}-SF{sub 6}), and 24.0 {plus minus} 0.8 {angstrom}{sup 2} (CH{sub 4}-SiH{sub 4}).
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- 1991
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15. 19F nuclear spin relaxation by intermolecular magnetic dipole coupling. CF4and SiF4in oxygen gas
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Joseph K. Hwang, A. Keith Jameson, and Cynthia J. Jameson
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Dipole ,Nuclear magnetic resonance ,Spin polarization ,Chemistry ,Intramolecular force ,Intermolecular force ,Relaxation (NMR) ,Spin–lattice relaxation ,General Physics and Astronomy ,Physical and Theoretical Chemistry ,Spin (physics) ,Magnetic dipole ,Molecular physics - Abstract
The 19F spin relaxation in CF4 in oxygen gas and in SiF4 in oxygen gas has been measured as a function of density, temperature, and magnetic field. The spin–rotation (intramolecular) and the nuclear spin dipole–electron spin dipole interactions (intermolecular) are the dominant mechanisms. The field dependence of the dipolar relaxation rates is characterized for CF4–O2 and SiF4–O2, and compared with those for other spherical top‐O2 systems. Agreement of theoretical estimates with the observed field dependence is satisfactory. The temperature dependences of the collision efficiencies for the CF4–O2 and SiF4–O2 intermolecular relaxation have been determined. The magnitudes are found to be roughly three times that for hard spheres.
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- 1991
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16. Dilation and evacuation of a single fetus after midtrimester PROM in previable twin pregnancy
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Joseph K. Hwang, Brian C. Brost, and William J. Watson
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Adult ,medicine.medical_specialty ,Fetal Membranes, Premature Rupture ,medicine.medical_treatment ,Twins ,Prom ,Risk Assessment ,Ultrasonography, Prenatal ,Multiple Gestation ,Dilatation and Curettage ,Young Adult ,Pregnancy ,medicine ,Humans ,Dilation and evacuation ,Twin Pregnancy ,Retrospective Studies ,business.industry ,Obstetrics ,Pregnancy Outcome ,Obstetrics and Gynecology ,medicine.disease ,Pregnancy Reduction, Multifetal ,female genital diseases and pregnancy complications ,Surgery ,Pregnancy Trimester, Second ,Pediatrics, Perinatology and Child Health ,Umbilical cord prolapse ,Gestation ,Female ,Pregnancy, Multiple ,business ,Premature rupture of membranes ,Follow-Up Studies - Abstract
Midtrimester premature rupture of membranes (PROM) is an unusual complication of multiple gestation that most often results in poor obstetric outcome. Presented are four cases of twin pregnancy complicated by preterm PROM and umbilical cord prolapse at 16 to 21 weeks' gestation. After a period of expectant management, dilation and evacuation of only the presenting fetus was performed with careful ultrasound guidance, to attempt delayed interval delivery. This resulted in pregnancy prolongation of 42 to 133 days for the remaining cotwins. Dilation and evacuation of a single demised fetus in twin pregnancy complicated by PROM and cord prolapse can be accomplished with favorable clinical outcome.
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- 2008
17. D & E of a single fetus after midtrimester PROM in previable twin pregnancy
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Joseph K. Hwang, Brian C. Brost, William J. Watson, Norman Davies, and Carl H. Rose
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Fetus ,medicine.medical_specialty ,Obstetrics ,business.industry ,medicine ,Obstetrics and Gynecology ,Prom ,business ,Twin Pregnancy - Published
- 2006
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18. Cross sections for the anisotropic interaction of NNO with various molecules
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Joseph K. Hwang, Cynthia J. Jameson, A. Keith Jameson, and Nancy C. Smith
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Range (particle radiation) ,Angular momentum ,Argon ,Xenon ,Chemistry ,Krypton ,Relaxation (NMR) ,General Physics and Astronomy ,chemistry.chemical_element ,Molecule ,Physical and Theoretical Chemistry ,Atomic physics ,Anisotropy - Abstract
Cross sections for the relaxation of the rotational angular momentum vector of the NNO molecule on collision with CO, Ar, CO2, NNO, Kr, CF4, and Xe, have been measured by 15N spin relaxation in 15N15NO molecules. The relaxation times of the two nuclei are in a ratio 1.86, independent of density, collision partner, or temperature. Except for Ar and CO, the cross sections are larger than the hard sphere cross sections and their temperature dependences range from T−0.8 to T−1.0.
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- 1988
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19. Nuclear spin relaxation by intermolecular magnetic dipole coupling in the gas phase.129Xe in oxygen
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Joseph K. Hwang, Cynthia J. Jameson, and A. Keith Jameson
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Chemistry ,Intermolecular force ,Relaxation (NMR) ,Spin–lattice relaxation ,General Physics and Astronomy ,chemistry.chemical_element ,Magnetic field ,NMR spectra database ,Spin–spin relaxation ,Xenon ,Physical and Theoretical Chemistry ,Atomic physics ,Nuclear Experiment ,Magnetic dipole - Abstract
The nuclear spin relaxation times (T1) of 129Xe in xenon–O2 gas mixtures have been measured as a function of temperature and density at different magnetic fields. This system is used to characterize the intermolecular dipolar relaxation of nuclear spins in the gas phase. An empirical Boltzmann‐averaged collision cross section associated with the collision‐induced transitions between 129Xe nuclear spin states is obtained as a function of temperature.
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- 1988
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20. Proton relaxation in methane with oxygen gas
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Joseph K. Hwang, A. Keith Jameson, and Cynthia J. Jameson
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chemistry.chemical_classification ,Proton ,General Engineering ,Champ magnetique ,Photochemistry ,Diatomic molecule ,Methane ,chemistry.chemical_compound ,chemistry ,Relaxation (physics) ,Physical and Theoretical Chemistry ,Oxygen gas ,Spin relaxation ,Inorganic compound ,Nuclear chemistry - Published
- 1989
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21. Competition of intra- and intermolecular spin relaxation mechanisms for SF6 in oxygen gas
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Joseph K. Hwang, Cynthia J. Jameson, A. Keith Jameson, and Diane Dabkowski
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Chemistry ,Stereochemistry ,Intermolecular interaction ,Intermolecular force ,General Engineering ,Spin–lattice relaxation ,Physical chemistry ,Champ magnetique ,Physical and Theoretical Chemistry ,Oxygen gas ,Spin relaxation - Abstract
Mesure des temps de relaxation de 19 F dans SF 6 dans l'oxygene, en fonction de la densite de O 2 et de la temperature dans trois champs magnetiques. Mise en evidence de la possibilite de separation en deux mecanismes: relaxation spin-rotation (intramoleculaire) et interaction dipole-dipole (intermoleculaire). Determination de la dependance du mecanisme de relaxation dipolaire vis-a-vis du champ et de la temperature
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- 1988
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