Evaluating Novel SP-B and SP-C Synthetic Analogues for Pulmonary Surfactant Efficacy

Pulmonary surfactants, a complex assembly of phospholipids and surfactant proteins such as SP-B and SP-C, are critical for maintaining respiratory system functionality by lowering surface tension (ST) and preventing alveolar collapse. Our study introduced five synthetic SP-B peptides and one SP-C peptide, leading to the synthesis of CHAsurf candidates (CHAsurf-1 to CHAsurf-5) for evaluation. We utilized a modified Wilhelmy balance test to assess the surface tension properties of the surfactants, measuring spreading rate, surface adsorption, and ST-area diagrams to comprehensively evaluate their performance. Animal experiments were performed on New Zealand white rabbits to test the efficacy of CHAsurf-4B, a variant chosen for its economic viability and promising ST reduction properties, comparable to Curosurf®. The study confirmed that higher doses of SP-B in CHAsurf-4 are associated with improved ST reduction. However, due to cost constraints, CHAsurf-4B was selected for in vivo assessment. The animal model revealed that CHAsurf-4B could restore alveolar structure and improve lung elasticity, akin to Curosurf®. Our research highlights the significance of cysteine residues and disulfide bonds in the structural integrity and function of synthetic SP-B analogues, offering a foundation for future surfactant therapy in respiratory disorders. This study's findings support the potential of CHAsurf-4B as a therapeutic agent, meriting further investigation to solidify its role in clinical applications.

Birth Rate Transition in the Republic of Korea: Trends and Prospects

BACKGROUND

In Korea, the birth rate is declining at an alarming pace. This study aimed to investigate the changes and trends in the population count, number of births, and birth rate in Korea, in the past and future.

METHODS

Data regarding the total number of births, crude birth rate, and total fertility rate were collected from the "Statistics Korea Census" of the national statistical portal, census report, and Statistics Korea's "2020 Population Trend Survey for 1981-2020, provisional results of birth and death statistics." We used the Organisation for Economic Co-operation and Development 2019 Family Database for the TFR. To develop a better understanding of the data in this study, we classified it according to the modern history of Korea.

RESULTS

The changes and trends in the number of births and fertility rate in Korea, after liberation, were due to the birth control policy that restricted births. In Korea's low fertility society, which began in the mid-2000s, the fertility rate dropped to below 0.84 in 2020, despite policies to improve the quality of the population. The death toll has reached 300,000, entering an era of population decline.

CONCLUSION

As we enter the era of population decline, we are in a direction that will cause various socioeconomic problems, from demographic problems to future population decline.

Trends in Birth Weight and the Incidence of Low Birth Weight and Advanced Maternal Age in Korea between 1993 and 2016

BACKGROUND

As the aging society progresses, the average age of mothers is also increasing. Advanced maternal age has been known to be associated with perinatal outcomes, as well as birth weight (BW). In this study, we aimed to investigate the perinatal factors associated with low birth weight infants (LBWIs) using birth statistics of the Korean population.

METHODS

Birth statistics between 1993 and 2016 from the Korean Statistical Information Service were reviewed. We investigated 12,856,614 data points, which included the number of births, BWs, percentage of preterm births and LBWIs, multiple pregnancies, and maternal age.

RESULTS

The proportion of LBWIs delivered by mothers of advanced maternal age has gradually increased since 1993. In addition, the proportion of older mothers (≥ 35 years old) giving birth to LBWIs has increased over the years. Average BW has a negative correlation with the ratio of preterm births, LBW, multiple births, and advanced maternal age. The mean BW also has a negative correlation with maternal age.

CONCLUSION

This study shows that the average BW continues to decline, and the incidence of LBWIs is increasing in Korea since 1993. This study also revealed that several perinatal factors, including percentage of preterm births, LBWIs, multiple births, and maternal age influence the mean BW. Although this study did not investigate the effects of decreasing mean BW on perinatal health, future research is worth discussing.

Association of Surfactant Protein with Expression of Hoxa5 and Hoxb5 in Rabbit Fetal Lung

Hox genes regulate organ formation and identity of the embryo, and expressed in specific temporo-spatial patterns in the developing embryo. We compared the expression levels of the Hoxa5, Hoxb5, surfactant protein (SP)-A, and SP-B genes in immature and mature rabbit fetal lung tissues, and to uncover roles for Hoxa5, Hoxb5, SP-A, and SP-B. Cesarean sections were performed after rabbits were divided into two groups of 30-31 days of gestation (term group, n = 24) and 26-27 days of gestation (preterm group, n = 24). mRNA levels of Hoxa5, Hoxb5, SP-A, and SP-B were compared by quantitative reverse transcriptase polymerase chain reaction, and protein expression of Hoxa5 and Hoxb5 was compared by western blot analysis. Fetal lung tissue histology was observed by hematoxylin and eosin (H&E) staining. The relative expression ratios of SP-A and SP-B mRNA in the term to preterm groups were 2.45:1 and 2.94:1, respectively. Hoxb5 mRNA and protein levels decreased in the term group, with a relative expression ratio of 0.48:1 and 0.50:1, however, Hoxa5 mRNA and protein levels increased in the term group with a relative expression ration of 2.99:1 and 2.33:1, respectively, for the term to preterm groups. Moreover, a significant positive correlation was found between the expression of Hoxa5 and SP-A, SP-B in the term group. Hoxa5 gene may be essential for the expression of SP-A and SP-B in term rabbits. The Hoxb5 gene may be an important factor for lung maturation in preterm rabbits.

Percentile Distributions of Birth Weight according to Gestational Ages in Korea (2010-2012)

The Pediatric Growth Chart (2007) is used as a standard reference to evaluate weight and height percentiles of Korean children and adolescents. Although several previous studies provided a useful reference range of newborn birth weight (BW) by gestational age (GA), the BW reference analyzed by sex and plurality is not currently available. Therefore, we aimed to establish a national reference range of neonatal BW percentiles considering GA, sex, and plurality of newborns in Korea. The raw data of all newborns (470,171 in 2010, 471,265 in 2011, and 484,550 in 2012) were analyzed. Using the Korean Statistical Information Service data (2010-2012), smoothed percentile curves (3(rd)-97(th)) by GA were created using the lambda-mu-sigma method after exclusion and the data were distinguished by all live births, singleton births, and multiple births. In the entire cohort, male newborns were heavier than female newborns and singletons were heavier than twins. As GA increased, the difference in BW between singleton and multiples increased. Compared to the previous data published 10 years ago in Korea, the BW of newborns 22-23 gestational weeks old was increased, whereas that of others was smaller. Other countries' data were also compared and showed differences in BW of both singleton and multiple newborns. We expect this updated data to be utilized as a reference to improve clinical assessments of newborn growth.

Changes in Survival Rate for Very-Low-Birth-Weight Infants in Korea: Comparison with Other Countries

Recently the Korean Neonatal Network (KNN) was established in order to enhance treatment outcomes further through the registration of very-low-birth-weight infants (VLBWI) data. The present study was conducted on 2,606 VLBWI, 2,386 registered and 220 un-registered, in the KNN participating centers, with the objective of reporting on recent survival rates of VLBWI in Korea and verifying the changing trends in survival rates with data from the 1960s and beyond. The study also aimed to compare the premature infants' survival rate in Korea with those reported in neonatal networks of other countries. The recent survival rate of VLBWI increased more than twice from 35.6% in the 1960s to 84.8%, and the survival rate of the extremely low birth weight infants (ELBWI) increased by more than 10 times, indicating improvement of the survival rate in premature infants with lower birth weight and gestational age. Comparison of VLBWI between countries showed improved survival rates according to each birth weight group in Canada, Australia-New Zealand, and European countries with Japan at the head, but in terms of comparison based on gestational age, differences, except for Japan, have been reduced. Efforts to increase the survival rate of premature infants in Korea with low birth rate are inevitable, and they should be the foundation of academic and clinical development based on its network with advanced countries.

Changes in the cesarean section rate in Korea (1982-2012) and a review of the associated factors

Although Cesarean section (CS) itself has contributed to the reduction in maternal and perinatal mortality, an undue rise in the CS rate (CSR) has been issued in Korea as well as globally. The CSR in Korea increased over the past two decades, but has remained at approximately 36% since 2006. Contributing factors associated with the CSR in Korea were an improvement in socio-economic status, a higher maternal age, a rise in multiple pregnancies, and maternal obesity. We found that countries with a no-fault compensation system maintained a lower CSR compared to that in countries with civil action, indicating the close relationship between the CSR and the medico-legal system within a country. The Korean government has implemented strategies including an incentive system relating to the CSR or encouraging vaginal birth after Cesarean to decrease CSR, but such strategies have proved ineffective. To optimize the CSR in Korea, efforts on lowering the maternal childbearing age or reducing maternal obesity are needed at individual level. And from a national view point, reforming health care system, which could encourage the experienced obstetricians to be trained properly and be relieved from legal pressure with deliveries is necessary.

Early prophylactic versus late selective use of surfactant for respiratory distress syndrome in very preterm infants: a collaborative study of 53 multi-center trials in Korea

Pulmonary surfactant (PS) therapy was proven to be highly successful for the treatment of respiratory distress syndrome in premature infants. As a results, early prophylactic (EP) PS therapy has been introduced recently in Europe, the US and Korea. However, no multi-center study was compared EP and late selective (LS) PS therapies in Korea. We performed a retrospective multi-center study to compare the outcomes of EP and LS PS therapies in very preterm infants. We analyzed clinical morbidity and mortality for 1,291 infants in 2010 (LS group) and 1,249 infants in 2011 (EP group); the infants were born <30 weeks of gestation and had birth weight ≤1,250 g, and were chosen from 53 neonatal intensive care units in Korea. Compared to the LS group (22.5%), the overall mortality was better in the EP group (19.9%) and there was no increased need for retreatment.There were additional benefits in the EP group such as fewer associated complications. To the best of knowledge, our study is the first nationwide Korean study to compare the outcomes of EP and LS therapies, and it provides evidences that EP PS therapy is important in very preterm infants to improve for survival and reduce morbidities.

Duplicate publication rate decline in Korean medical journals

The purpose of this study was to examine trends in duplicate publication in Korean medical articles indexed in the KoreaMed database from 2004 to 2009, before and after a campaign against scientific misconduct launched by the Korean Association of Medical Journal Editors in 2006. The study covered period from 2007 to 2012; and 5% of the articles indexed in KoreaMed were retrieved by random sampling. Three authors reviewed full texts of the retrieved articles. The pattern of duplicate publication, such as copy, salami slicing (fragmentation), and aggregation (imalas), was also determined. Before the launching ethics campaign, the national duplication rate in medical journals was relatively high: 5.9% in 2004, 6.0% in 2005, and 7.2% in 2006. However, duplication rate steadily declined to 4.5% in 2007, 2.8% in 2008, and 1.2 % in 2009. Of all duplicated articles, 53.4% were classified as copies, 27.8% as salami slicing, and 18.8% as aggregation (imalas). The decline in duplicate publication rate took place as a result of nationwide campaigns and monitoring by KoreaMed and KoreaMed Synapse, starting from 2006.

Trends of breastfeeding rate in Korea (1994-2012): comparison with OECD and other countries

Breastfeeding has numerous benefits both for infants and mothers. WHO, UNICEF, and OECD report the breastfeeding rate (BR) and exclusive breastfeeding rate (EBR) at 3, 4, and 6 months of age for the international comparison. This article investigates the nationwide changes in BR and EBR in Korea from 1994 to 2012. EBR declined from 1994 to 2000, however progressively increased untill 2012. The latest data in 2012 revealed EBRs at 3, 4, and 6 months were 50.0%, 40.5%, and 11.4% respectively. The exclusive formula feeding rate (EFR) was highest in 2000 and gradually declined thereafter. In 2012, the EFRs at 3, 4 and 6 months were 21.7%, 26.5%, and 10.1%. In 2009, the EBRs at 3 and 6 months in the United States were 36.0% and 16.3% compared to 50.0% and 11.4% in Korea. In England, the EBRs were 17% and 12% in 2010. Amongst OECD countries, Hungary ranked highest EBRwith 95%, and Iceland, Norway, Slovak Republic, Australia, New Zealand followed. In conclusion, BRs were lowest in 2000, and there have been remarkable increases in BRs over the past 10 yr in Korea. Although BRs have been increasing, further efforts to increase BRs should be made continuously.

Decreased expression of surfactant protein genes is associated with an increased expression of Forkhead box M1 gene in the fetal lung tissues of premature rabbits

PURPOSE

Recently, Forkhead box M1 (FoxM1) was reported to be correlated with lung maturation and expression of surfactant proteins (SPs) in mice models. However, no study has been conducted in rabbit lungs despite their high homology with human lungs. Thus, we attempted to investigate serial changes in the expressions of FoxM1 and SP-A/B throughout lung maturation in rabbit fetuses.

MATERIALS AND METHODS

Pregnant New Zealand White rabbits were grouped according to gestational age from 5 days before to 2 days after the day of expected full term delivery (F5, F4, F3, F2, F1, F0, P1, and P2). A total of 64 fetuses were enrolled after Cesarean sections. The expressions of mRNA and proteins of FoxM1 and SP-A/B in fetal lung tissue were tested by quantitative reverse-transcriptase real-time PCR and Western blot. Furthermore, their correlations were analyzed.

RESULTS

The mRNA expression of SP-A/B showed an increasing tendency positively correlated with gestational age, while the expression of FoxM1 mRNA and protein decreased from F5 to F0. A significant negative correlation was found between the expression levels of FoxM1 and SP-A/B (SP-A: R=-0.517, p=0.001; SP-B: R=-0.615, p<0.001).

CONCLUSION

Preterm rabbits demonstrated high expression of FoxM1 mRNA and protein in the lungs compared to full term rabbits. Also, the expression of SP-A/B was inversely related with serial changes in FoxM1 expression. This is the first report to suggest an association between FoxM1 and expression of SP-A/B and lung maturation in preterm rabbits.

Current status of production and market of human vaccine products in Korea

Purpose

The goal of this study was to build basic information related to the production and market of human vaccine products in Korea, which can be an important indicator to provide basic data in practical use.

Materials and Methods

Statistical data were obtained from the Bank of Korea, Korea Health Industry Development Institute, Korea Pharmaceutical Traders Association, and Korea Pharmaceutical Manufacturers Association.

Results

Vaccines are the 10th ranked drugs in the classification of whole complete preparated drugs. The production output of vaccines in Korea was 392.2 billion KRW in 2011, comprising 2.83% of complete preparated drug production output (13 trillion 880.8 billion KRW) and 2.54% of medical-pharmaceutical product output (15 trillion 440.3 billion KRW). The market scale of vaccines in Korea was 710 billion KRW in 2011, with an annual average growth rate of 11% in the past 6 years, comprising 2% of vaccine market in the world. There was also a significant increase in essential vaccines and other preventive vaccines in a global scale.

Conclusion

Vaccines have the potential of becoming an emerging attractive industry. Based on the current analysis about the production of vaccine products and market scale, further development of the vaccine industry is expected in Korea.

Serum cystatin C during 30 postnatal days is dependent on the postconceptional age in neonates

BACKGROUND

Cystatin C (CysC) is a promising endogenous marker for renal function. However, the reference serum CysC level is not sufficiently studied in neonates. This study was conducted to investigate the reference level of serum CysC for neonates, including very low birth weight infants according to the postconceptional age (PCA).

METHODS

Serum CysC levels were measured in 883 blood samples (246 neonates including 127 premature infants). Infants with symptoms or signs of acute kidney injury, systemic illness, congenital anomaly, or renal pathology were excluded. CysC levels were analyzed for association between subgroups dichotomized by postnatal age and PCA.

RESULTS

Reference ranges of serum CysC were determined and a decreasing trend of CysC levels was observed as PCA increased, except for the first 3 postnatal days. CysC levels were negatively correlated with gestational age at birth, and PCA (P < 0.001), while positively correlated with postnatal age and serum creatinine (P < 0.001).

CONCLUSION

The reference level of serum CysC was determined according to postnatal age and PCA. As the reference CysC level was dependent on gestational age and PCA, consideration of these parameters is warranted when assessing CysC levels in neonates.

Medical papers related to keywords of vaccine and vaccination in KoreaMed database, Korea (1962-2012)

Purpose

To describe the present status and changing patterns of medical papers related to keywords of vaccine and vaccination published in Korea over the last 50 years, and provide basic data for future studies.

Materials and Methods

185,603 papers are registered in the medical database KoreaMed, which is run by Korean Association of Medical Journal Editors. Among these papers, a search with the keywords vaccine or vaccination revealed a total of 1,089 articles which were published on vaccine and/or vaccination during the period of September 2, 1962 to April 30, 2012. Our study endeavors to analyze these 1,089 articles.

Results

Only one article published with the keywords vaccine and/or vaccination was published in the 1960s, and the number of journals steadily increased starting from the 1970s (24 articles) to 2 times, 10 times, 20 times in the 1980s, 1990s, and the 2000s (585 articles), respectively. The articles were classified into reviews (20.2%), original articles with clinical study (40.7%), original articles with experimental study (24.6%), and case reports (8.2%). The review articles mainly dealt with an overview. The original articles with clinical study were on epidemiology, effect and immunogenicity, clinical trial. Original articles with experimental study were mainly comprised of complication and overview. Articles on vaccine, pathogen or disease topics were mostly microorganisms such as bacteria or viruses, and studies on anti-cancer vaccines or vaccines of specific diseases were sparse.

Conclusion

The above data reflects the clinical uses of vaccines in Korea and the history of vaccine studies. The number of vaccine-related articles is increasing rapidly since the first article was published in 1962. This implies that with the increase of studies of clinical trials, clinical uses and results and analyses of the results, articles relating to basic studies are also on the rise. We intend these findings to be of use to researchers in this active and expanding field.

Current status of registry of vaccine clinical trials conducted by Korean investigators in ClinicalTrials.gov, database of US National Institutes of Health

Purpose

PubMed is not only includes international medical journals but also has a registration site for the ongoing clinical trials, such as ClinicalTrials.gov, under the supervision of US National Institutes of Health. We analyzed current status of vaccine clinical trials conducted by Korean investigators in database of ClinicalTrial.gov.

Materials and Methods

As of October 2012, there are total of 72 trials found on registry of vaccine clinical trials conducted by Korean investigators in database of ClinicalTrial.gov. These trials were analyzed and classified by conditions of vaccine clinical trials, biologicals or drugs used in vaccine clinical trials, status of proceeding research, and list of sponsor and collaborators.

Results

Total 72 trials of vaccine clinical trials conducted by Korean investigators are classified by groups of infection (64 trials), cancer (4 trials), and others (4 trials). Infections group shown are as follows: poliomyelitis, pertussis, diphtheria, tetanus, and Haemophilus influenzae type b (10), influenza (9), human papillomavirus infection (8), pneumococcal vaccine (6), herpes zoster (4), smallpox (4), hepatitis B (4), etc. One trial of each in lung cancer, breast cancer, prostate cancer, and colorectal cancer are shown in cancer group. One trial of each in Crohn's disease, ulcerative colitis, renal failure, and rheumatoid arthritis are shown in other group.

Conclusion

Vaccine clinical trials conducted by Korean investigators in ClinicalTrial.gov reflects the current status of Korean research on vaccine clinical trials at the international level and can indicate research progress. It is hoped that this aids the development of future vaccine clinical trials in Korea.

Birth statistics of high birth weight infants (macrosomia) in Korea

Purpose

The authors analyzed the trend from the birth-related statistics of high birth weight infants (HBWIs) over 50 years in Korea from 1960 to 2010.

Methods

We used 2 data sources, namely, the hospital units (1960's to 1990's) and Statistics Korea (1993 to 2010). The analyses include the incidence of HBWIs, birth weight distribution, sex ratio, and the relationship of HBWI to maternal age.

Results

The hospital unit data indicated the incidence of HBWI as 3 to 7% in the 1960's and 1970's and 4 to 7% in the 1980's and 1990's. Data from Statistics Korea indicated the percentages of HBWIs among total live births decreased over the years: 6.7% (1993), 6.3% (1995), 5.1% (2000), 4.5% (2000), and 3.5% (2010). In HBWIs, the birth weight rages and percentage of incidence in infants' were 4.0 to 4.4 kg (90.3%), 4.5 to 4.9 kg (8.8%), 5.0 to 5.4 kg (0.8%), 5.5 to 5.9 kg (0.1%), and >6.0 kg (0.0%) in 2000 but were 92.2%, 7.2%, 0.6%, 0.0%, and 0.0% in 2009. The male to female ratio of HBWIs was 1.89 in 1993 and 1.84 in 2010. In 2010, the mother's age distribution correlated with low (4.9%), normal (91.0%), and high birth weights (3.6%): an increase in mother's age resulted in an increase in the frequency of low birth weight infants (LBWIs) and HBWIs.

Conclusion

The incidence of HBWIs for the past 50 years has been dropping in Korea. The older the mother, the higher was the risk of a HBWI and LBWI. We hope that these findings would be utilized as basic data that will aid those managing HBWIs.

Surfactant lavage therapy for meconium aspiration syndrome: a systematic review and meta-analysis

BACKGROUND

Lung lavage with diluted surfactant has emerged as an innovative treatment for meconium aspiration syndrome (MAS). However, the treatment effect has not yet been fully established.

OBJECTIVE

To investigate the effects of surfactant lavage therapy for MAS by a systematic meta-analysis.

METHODS

Relevant studies were identified by database searches in MEDLINE (from 1950), EMBASE (from 1980), and CENTRAL, up to June 2010, and by additional hand searches. Meta-analyses were separately conducted for randomized controlled trials (RCTs) and non-randomized controlled studies (NRSs). Risk of bias was assessed and clinical as well as statistical heterogeneities were also investigated in explaining the potential bias.

RESULTS

Two RCTs (87 patients) and eight NRSs (178 patients) were identified. From the results of the meta-analysis of RCTs, surfactant lavage significantly decreased death or the need for extracorporeal membrane oxygenation (RR 0.34, 95% CI 0.11, 0.99). An interventional benefit was indicated for other outcomes, although it was not statistically significant based only on the two RCTs. Results from the analysis of outcomes from NRSs are consistent with those from RCTs and demonstrated a beneficial effect, which could be considered as supporting evidence.

CONCLUSIONS

Lung lavage with diluted surfactant appeared to improve the clinical outcome in infants with MAS. Given that less than 100 infants were included in the two RCTs, the findings of this study may still be regarded as insufficient evidence. Further research will be needed to confirm the benefit as well as to refine the lavage technique.

Changes in the neonatal and infant mortality rate and the causes of death in Korea

Neonatal mortality rate (NMR) or infant mortality rate (IMR) are the rate of deaths per 1,000 live births at which babies of either less than four weeks or of one year of age die, respectively. The NMR and IMR are commonly accepted as a measure of the general health and wellbeing of a population. Korea's NMR and IMR fell significantly between 1993 and 2009 from 6.6 and 9.9 to 1.7 and 3.2, respectively. Common causes of infantile death in 2008 had decreased compared with those in 1996 such as other disorders originating in the perinatal period, congenital malformation of the heart, bacterial sepsis of newborns, disorders related to length of gestation and fetal growth, intra-uterine hypoxia, birth asphyxia. However, some other causes are on the increase, such as respiratory distress of newborn, other respiratory conditions originating in the perinatal period, other congenital malformation, diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism. In this study, we provide basic data about changes of NMR and IMR and the causes of neonatal and infantile death from 1983 to 2009 in Korea.

Decreasing trends of neonatal and infant mortality rates in Korea: compared with Japan, USA, and OECD nations

Neonatal mortality rate (NMR) and infant mortality rate (IMR) are two of the most important indices reflecting the level of public health of a country. In this review, we investigated changes in NMR and IMR in Korea and compared the results with those of Japan, USA, and OECD nations. During the past 20 yr, NMR and IMR have lowered remarkably from 6.6 and 9.9 in 1993 to 1.7 and 3.2 in 2009, respectively, in Korea. It is an impressive finding that Korean IMR (3.2 in 2009) is lower than the average of OECD nations (4.7 in 2008), and USA (6.3 in 2009), although higher than Japanese IMR (2.8 in 2009). The proportion of NMR among the IMR calculation decreased from 66.7% in 1993 to 53.1% in 2009. The reason the value of Korea was higher than Japan but lower than USA was speculated to be an aspect of the health care service system. Several suggestions in perinatal, neonatal and infantile health care such as establishment of perinatal care center, research network system, regionalization, and new policies for care of pre-term and high risk pregnancy, are elucidated to achieve further improvement on NMR and IMR in Korea.

Novel compound heterozygous mutations in the vitamin D receptor gene in a Korean girl with hereditary vitamin D resistant rickets

Hereditary vitamin D resistant rickets (HVDRR) is a rare genetic disorder caused by a mutation of vitamin D receptor (VDR) gene. A number of cases had been reported in many countries but not in Korea. We examined a three-year old Korean girl who had the typical clinical features of HVDRR including rickets, hypocalcemia, hypophosphatemia, elevated serum calcitriol level and secondary hyperparathyroidism. The girl and her father were both heterozygous for the 719C-to-T(I146T)---> c.437C > T(p.T1461) [corrected] mutation in exon 4, whereas she and her mother were both heterozygous for 754C-to-T (R154C)---> c.472 > T(p.R158C) [corrected] mutation in exon 5 of the VDR gene. In this familial study, we concluded that the girl had compound heterozygous mutations in her VDR gene which caused HVDRR. This is the first report of a unique mutation in the VDR gene in Korea.

Recent trends in neonatal mortality in very low birth weight Korean infants: in comparison with Japan and the USA

With regard to the outcome of intensive neonatal care, one of the most important concerns in neonatology is the mortality rate of very low birth weight infants (VLBWI; birth weight < 1,500 g) and extremely low birth weight infants (ELBWI; birth weight < 1,000 g). The present study was conducted to analyze and compare the mortality of VLBWI and ELBWI and neonatal care among Korean, Japanese, and American newborns. In Korea, the survival rates of VLBWI have increased significantly; they were 31.8% in the early 1960s, 65.8% in the early 1990s, 77.5% in 2002, 84.7% in 2007, and 85.7% in 2009. The survival rates of ELBWI have also increased; they were 8.2% in the early 1960s, 37.4% in the early 1990s, 56.1% in 2002, 67.7% in 2007, and 71.8% in 2009. The survival rates of VLBWI and ELBWI have significantly improved over the past 50 yr in Korea. However, the Korean survival rates of VLBWI and ELBWI are still lower than for similar groups in Japan and the USA. To achieve better outcomes that reach the level of these countries, the organization of perinatal care centers, nationwide neonatal perinatal research networks, and regionalization are needed in Korea.

Multiple births conceived by assisted reproductive technology in Korea

PURPOSE

The recent trends of multiple births (MBs) conceived by assisted reproductive technology (ART) in Korea were analyzed as well as the relationship with maternal age, especially advanced maternal age.

METHODS

Data were obtained from the Korean Statistical Information Service and annual ART reports from the ART committee of the Korean Society of Obstetrics and Gynecology.

RESULTS

MBs increased from the early 1990s; there was a 275% increase by 2008. The number of total live births was 448,153 and MBs accounted for 10,767; the MB rate was 24.0% in 2006. Among 2,326 deliveries conceived by ART, multiple deliveries accounted for 786 (33.8%). The total number of live births with ART was 3,125 and 1,585 (50.7%) of them were MBs. During 2006, 14.7% of the entire MBs in Korea were associated with ART. The proportion of women of advanced maternal age was much higher in the ART group than in the total live birth group.

CONCLUSION

MBs in women of advanced maternal age have been increasing in Korea with the use of ART. The results of this study showed that ART was a significant factor associated with the increase in MBs in Korea.

Recent trends in the incidence of multiple births and its consequences on perinatal problems in Korea

The aim of this study was to survey multiple birth data and to analyze the recent trends of multiple births and its consequences on perinatal problems in Korea from 1991 to 2008. Data were obtained from the Korean Statistical Information Service. The total number of multiple births showed increasing trends. The multiple birth rate was maintained within less than 10.0 for the decade from 1981 to 1990. However, it increased gradually to reach 27.5 in 2008. The maternal age for multiple births was higher than for total live births. The mean birth weight of the total live births was 3.23 kg; for the multiple births it was 2.40 kg in 2008. The incidence of low birth weight infants (LBWI) among total live births was 3.8% in 2000 and 4.9% in 2008. For multiple births it was 49.2% and 53.0% during the same years. The incidence of preterm births among total live births was 3.8% in 2000 and 5.5% in 2008; for the multiple births it was 38.3% and 51.5% during the same years. The incidence of multiple births and its consequences on perinatal problems (preterm, LBWI, and advanced-maternal age) have been increased steadily over the last two decades in Korea.

Effect of exogenous surfactant therapy on levels of pulmonary surfactant proteins A and D in preterm infants with respiratory distress syndrome

OBJECTIVES

To examine whether exogenous pulmonary surfactants (exPS) substitute for or merely supplement endogenous pulmonary surfactants (enPS) by looking at sequential changes in the surfactant proteins (SP) SP-A and SP-D in alveolar pools.

METHODS

Fourteen preterm infants with RDS treated with an artificial surfactant were compared to five normal-term infants without RDS who were treated with artificial ventilation at birth.

RESULTS

Immediately after birth, SP-A and SP-D were essentially absent in the alveolar pools of the RDS group, but were present at normal levels in the controls. Treatment with exPS apparently stimulated enPS production.

CONCLUSIONS

In infants who responded well to exPS therapy, the SP concentration reached essentially normal levels within 48-72 h after birth.

Surfactant therapy for neonatal respiratory distress syndrome: a review of Korean experiences over 17 years

We undertook a multi-hospital collective study to evaluate outcomes of neonatal respiratory distress syndrome (RDS) patients treated with pulmonary surfactant (PS) over 17 yr in Korea (Group I; 1990/91, Group II; 1996, Group III; 2002, and Group IV; 2007). There were 60 neonates in Group I (16 hospitals), 1,179 in Group II (64), 1,595 in Group III (62), and 1,921 in Group IV (57). We adopted Bomsel's classification to evaluate initial chest radiographic findings, categorized RDS severities, and classified response types to PS therapy. Almost all cases were treated using a single dose in Groups I and II, but 19.5% received multiple-dose therapy in Group IV. In Group IV, Bomsel's stages III and IV composed 62.9% and initial severities of mild, moderate, and severe RDS were 23.0%, 42.0%, and 35.0%. More infants showed good response in Groups II, III, and IV than in Group I (71.7%, 66.8%, and 69.2% vs. 58.3%). Complications and mortality rate were lower in Group IV than in Groups I, II, and III (mortality rate: 14.3% vs. 40.0%, 30.0%, and 18.7%). We conclude that PS therapy in neonates with RDS had a remarkable impact on improving clinical course and outcomes over 17 yr in Korea.

Duplicate Publications in Korean medical journals indexed in KoreaMed

Duplicate publication is considered unethical. It has several negative impacts. To estimate the frequency and characteristics of duplicate publications in Korean medical journals, we reviewed some portion of Korean journal articles. Among 9,030 articles that are original articles indexed in KoreaMed from January to December 2004, 455 articles (5%) were chosen by random sampling. PubMed, Google scholar, KMbase, and KoreaMed were searched by two librarians. Three authors reviewed titles, abstracts, and full text of index articles and suspected articles independently. Point of disagreement were reconciled by discussion. Criteria for a duplicate publication defined by editors of cardiothoracic journals and International Committee of Medical Journal Editors were used. A total of 455 articles were evaluated, of which 27 (5.93%) index articles were identified with 29 duplicate articles. Among 27 index articles, 1 was quadruple publication and 26 were double publications. Of 29 duplicated articles, 19 were classified as copy, 4 as fragmentation, and 6 as disaggregation. The proportion of duplicate publications in Korean medical journals appears to be higher than expected. Education on publication ethics to researchers is needed.