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.

A Combination of Short and Simple Surfactant Protein B and C Analogues as a New Synthetic Surfactant: In Vitro and Animal Experiments.

PURPOSE: Pulmonary surfactants for preterm infants contain mostly animal-derived surfactant proteins (SPs), which are essential for lowering surface tension. We prepared artificial pulmonary surfactants using synthetic human SP analogs and performed in vitro and in vivo experiments. MATERIALS AND METHODS: We synthesized peptide analogues that resemble human SP-B (RMLPQLVCRLVLRCSMD) and SP-C (CPVHLKRLLLLLLLLLLLLLLLL). Dipalmitoylphosphatidylcholine (DPPC), phosphatidylglycerol (PG), and palmitic acid (PA) were added and mixed in lyophilized to render powdered surfactant. Synsurf-1 was composed of DPPC:PG:PA:SP-B (75:25:10:3, w/w); Synsurf-2 was composed of DPPC:PG:PA:SP-C (75:25:10:3, w/w); and Synsurf-3 was composed of DPPC:PG:PA:SP-B:SP-C (75:25:10:3:3, w/w). We performed in vitro study to compare the physical characteristics using pulsating bubble surfactometer and modified Wilhelmy balance test. Surface spreading and adsorption test of the surfactant preparations were measured. In vivo test was performed using term and preterm rabbit pups. Pressure-volume curves were generated during the deflation phase. Histologic findings were examined. RESULTS: Pulsating bubble surfactometer readings revealed following minimum and maximum surface tension (mN/m) at 5 minutes: Surfacten® (5.5±0.4, 32.8±1.6), Synsurf-1 (16.7±0.6, 28.7±1.5), Synsurf-2 (7.9±1.0, 33.1±1.6), and Synsurf-3 (7.1±0.8, 34.5±1.0). Surface spreading rates were as follows: Surfacten® (27 mN/m), Synsurf-1 (43 mN/m), Synsurf-2 (27 mN/m), and Synsurf-3 (27 mN/m). Surface adsorption rate results were as follows: Surfacten® (28 mN/m), Synsurf-1 (35 mN/m), Synsurf-2 (29 mN/m), and Synsurf-3 (27 mN/m). The deflation curves were best for Synsurf-3; those for Synsurf-2 were better than those for Surfacten®. Synsurf-1 was the worst surfactant preparation. Microscopic examination showed the largest aerated area of the alveoli in the Synsurf-3 group, followed by Synsurf-1 and Surfacten®; Synsurf-2 was the smallest. CONCLUSION: Synsurf-3 containing both SP-B and SP-C synthetic analogs showed comparable and better efficacy than commercially used Surfacten® in lowering surface tension, pressure-volume curves, and tissue aerated area of the alveoli.

Decreased Cystatin C-Estimated Glomerular Filtration Rate Is Correlated with Prolonged Hospital Stay in Transient Tachypnea of Newborn Infants.

BACKGROUND: Transient tachypnea of the newborn (TTN) is a benign disorder with a variable clinical course that often leads to hospitalization. The aim of this study was to assess and validate the relationship between the serum cystatin C level and symptom duration in infants with TTN. METHODS: Forty newborns presenting with TTN and who had undergone serum cystatin C (Cys C) tests on the first day of admission to the Kyung Hee University Hospital (Seoul, Korea) from 2009 to 2013 were included. The serum Cys C level, creatinine (Cr) level, estimated glomerular filtration rate (eGFR), and tachypnea duration were correlated retrospectively. RESULTS: The median gestation period was 37.8 ± 3.8 weeks and the mean birth weight was 3.2 ± 0.4 kg. Tachypnea duration was 3.3 ± 2.0 days. Serum Cys C and Cr levels were 1.7 ± 0.2 mg/L and 0.8 ± 1.2 mg/dL, respectively. Tachypnea duration was significantly positively correlated with the serum levels of Cys C and significantly negatively correlated with Cys C-based eGFR (p = 0.016), but was not significantly correlated with the serum Cr level or Cr-based eGFR. When tachypnea duration was compared between infants with Cys C level <1.6 mg/L (n = 15; Group A) and infants with Cys C level ≥ 1.6 mg/L (n = 25; Group B), the symptom duration was significantly shorter in Group A infants (p = 0.011). CONCLUSION: Tachypnea duration was shorter with higher Cys C-based eGFR in infants with TTN.

Development of a Synthetic Surfactant Using a Surfactant Protein-C Peptide Analog: In Vitro Studies of Surface Physical Properties.

PURPOSE: Pulmonary surfactant (PS) replacement has been the gold standard therapy for neonatal respiratory distress syndrome; however, almost all commercial PSs contain animal proteins. We prepared a synthetic PS by using a human surfactant protein (SP) analog and evaluated its in vitro properties. MATERIALS AND METHODS: A peptide sequence (CPVHLKRLLLLLLLLLLLLLLLL) of human SP-C was chosen to develop the peptide analog (SPa-C). The new synthetic SP-C PS (sSP-C PS) was synthesized from SPa-C, dipalmitoyl phosphatidylcholine, phosphatidyl glycerol, and palmitic acid. Physical properties of the sSP-C PS were evaluated by measuring the maximum and minimum surface tensions (STs), surfactant spreading, and adsorption rate. In addition, we recorded an ST-area diagram. The data obtained on sSP-C PS were subsequently compared with those of purified natural bovine surfactant (PNBS), and the commercial product, Surfacten®. RESULTS: The sSP-C PS and Surfacten® were found to have maximum ST values of 32-33 mN/m, whereas that of PNBS was much lower at 19 mN/m. The minimum ST values of all three products were less than 10 mN/m. The values that were measured for the equilibrium ST of rapidly spreading sSP-C PS, Surfacten®, and PNBS were 27, 27, and 24 mN/m, respectively. The surface adsorptions were found to be the same for all three PSs (20 mN/m). ST-area diagrams of sSP-C PS and Surfacten® revealed similar properties. CONCLUSION: In an in vitro experiment, the physical properties exhibited by sSP-C PS were similar to those of Surfacten®. Further study is required to evaluate the in vivo efficacy.

Reference intervals of serum cystatin C/creatinine ratio of 30 postnatal days in neonates.

BACKGROUND: A number of recent reports have suggested that the cystatin C/creatinine (CysC/Cr) ratio might be a useful biomarker of renal function in pediatric patients. In this study we investigated the reference intervals of the serum CysC/Cr ratio for neonates including very low birth weight infants. CASE-DIAGNOSIS/TREATMENT: A total of 883 blood samples were collected from 246 neonates during the first 30 days of life for the concurrent measurement of serum CysC and Cr levels. Infants with symptoms or signs of acute kidney injury, systemic illness, congenital anomaly, or renal pathology were excluded. The association between serum CysC/Cr ratio and the subgroups of patients was also analyzed. Reference intervals of serum CysC/Cr ratio were determined according to the postnatal age and post-conceptional age (PCA). CysC/Cr ratio level increased according to PCA, except in the first three postnatal days. The serum CysC/Cr ratio correlated positively with gestational age at birth, birth weight, postnatal age, and PCA, and negatively with serum CysC and Cr (P < 0.001). CONCLUSIONS: Reference levels of serum CysC/Cr ratio were determined according to postnatal age and PCA. As the serum CysC/Cr ratio is dependent on several clinical parameters, these should be considered when assessing the serum CysC/Cr ratio in neonates.

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.

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.

Two cases of female hydrocele of the canal of nuck.

The processus vaginalis within the inguinal canal forms the canal of Nuck, which is a homolog of the processus vaginalis in women. Incomplete obliteration of the processus vaginalis causes indirect inguinal hernia or hydrocele of the canal of Nuck, a very rare condition in women. Here, we report 2 cases of hydrocele of the canal of Nuck that were diagnosed with ultrasonography in both cases and magnetic resonance imaging in 1 case to confirm the sonographic diagnosis. High ligation and hydrocelectomy were conducted in both patients. In 1 patient, 14 months later, the occurrence of contralateral inguinal hernia was suspected, but did not require surgery. The other patient had a history of surgery for left inguinal hernia 11 months before the occurrence of right hydrocele of the canal of Nuck. In both cases, the occurrence of an inguinal hernia on the contralateral side was noted.

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.

Ghrelin suppresses tunicamycin- or thapsigargin-triggered endoplasmic reticulum stress-mediated apoptosis in primary cultured rat cortical neuronal cells.

Ghrelin functions as a neuroprotective agent and rescues neurons from various insults. However, the molecular mechanisms underlying ghrelin neuroprotection remains to be elucidated. An accumulation of unfolded proteins in the endoplasmic reticulum (ER) leads to ER stress and then induces ER stress-mediated cell death. Here, we report that acylated ghrelin inhibited tunicamycin- or thapsigargin-triggered ER stress-induced apoptotic cell death in primary rat cortical neurons. An analysis using a specific inhibitor of phosphatidylinositol-3-kinase (PI3K), LY294002, showed that ghrelin prevented apoptosis via the activation of PI3K signaling pathway. Ghrelin suppressed tunicamycin- or thapsigargin-induced upregulation and nuclear translocation of C/EBP homologous protein (CHOP). Ghrelin also inhibited tunicamycin or thapsigargin induction of PRK-like ER kinase (PERK), eukaryotic translation initiation factor-2α (eIF2α) and activating transcription factor (ATF) 4. Exposure of cells to tunicamycin or thapsigargin resulted in nuclear translocation of forkhead box protein O1 (Foxo1), which was reduced by pretreatment with ghrelin. The protective effect of ghrelin was accompanied by an increased phosphorylation of Akt and glycogen synthase kinase (GSK)-3ß. Furthermore, ghrelin phosphorylated and inactivated pro-apoptotic BAD and Foxo1. In addition, phospho-Akt was translocated to the nucleus in response to ghrelin and PI3K inhibition by LY294002 prevented ghrelin-induced effect on phospho-Akt localization. Our study suggests that suppression of CHOP activation via the inhibition of PERK/eIF2α/ATF4 pathway and prevention of Foxo1 activation and nuclear translocation may contribute to ghrelin-mediated neuroprotection during ER stress responses. Our data also suggest that PI3K/Akt-mediated inactivation of GSK-3ß, BAD and Foxo1 may be associated with the anti-apoptotic effect of ghrelin.