The Effect of the Mechanical Properties of the 3D Printed Gelatin/ Hyaluronic Acid Scaffolds on hMSCs Differentiation Towards Chondrogenesis

BACKGROUND@#Tissue engineering, including 3D bioprinting, holds great promise as a therapeutic tool for repairing cartilage defects. Mesenchymal stem cells have the potential to treat various fields due to their ability to differentiate into different cell types. The biomimetic substrate, such as scaffolds and hydrogels, is a crucial factor that affects cell behavior, and the mechanical properties of the substrate have been shown to impact differentiation during incubation. In this study, we examine the effect of the mechanical properties of the 3D printed scaffolds, made using different concentrations of cross-linker, on hMSCs differentiation towards chondrogenesis. @*METHODS@#The 3D scaffold was fabricated using 3D bioprinting technology with gelatin/hyaluronic acid (HyA) biomaterial ink. Crosslinking was achieved by using different concentrations of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methlymorpholinium chloride n-hydrate (DMTMM), allowing for control of the scaffold’s mechanical properties. The printability and stability were also evaluated based on the concentration of DMTMM used. The effects of the gelatin/HyA scaffold on chondrogenic differentiation was analyzed by utilizing various concentrations of DMTMM. @*RESULTS@#The addition of HyA was found to improve the printability and stability of 3D printed gelatin/HyA scaffolds.The mechanical properties of the 3D gelatin/HyA scaffold could be regulated through the use of different concentrations of DMTMM cross-linker. In particular, the use of 0.25 mM DMTMM for crosslinking the 3D gelatin/HyA scaffold resulted in enhanced chondrocyte differentiation. @*CONCLUSION@#The mechanical properties of 3D printed gelatin/HyA scaffolds cross-linked using various concentrations of DMTMM can influence the differentiation of hMSCs into chondrocytes.

Low-Dose Ionizing γ-Radiation Promotes Proliferation of Human Mesenchymal Stem Cells and Maintains Their Stem Cell Characteristics

Mesenchymal stem cells (MSCs), which are multipotent and have self-renewal ability, support the regeneration of damaged normal tissue. A number of external stimuli promote migration of MSCs into peripheral blood and support their participation inwound healing. In an attempt to harness the potential beneficial effects of such external stimuli, we exposed human MSCs (hMSCs) to one such stimulus-low-dose ionizing radiation (LDIR)-and examined their biological properties. To this end, we evaluated differences in proliferation, cell cycle, DNA damage, expression of surface markers (CD29, CD34, CD90, and CD105), and differentiation potential ofhMSCs before and after irradiation with γ-rays generated using a ¹³⁷ CSirradiator.At doses less than 50 mGy, LDIR had no significant effect on the viability or apoptosis of hMSCs. Interestingly, 10 mGyofLDIR increased hMSC viability by 8% (p<0.001) comparedwith non-irradiatedhMSCs.At doses less than 50 mGy, LDIR did not induceDNA damage, including DNA strand breaks, or cause cellular senescence or cell-cycle arrest. Surface marker expression and in vitro differentiation potential of hMSCs were maintained after two exposures to LDIR at 10 mGy per dose. In conclusion, a two-dose exposure to LDIR at 10 mGy per dose not only facilitates proliferation of hMSCs, it alsomaintains the stem cell characteristics of hMSCswithout affecting their viability.These results provide evidence for the potential ofLDIRas an external stimulus for in vitro expansion of hMSCs and application in tissue engineering and regenerative medicine.

Korean Multicenter Study of Te tanus Antibody Titer (KoMUST)

PURPOSE: We determine the Korean antibody titer and positive rate of tetanus by using a with qualitative test (ELISA) and a quantitative test (TQS(R)). METHODS: This study was prospective collecting study with uncontolled patients who were admitted in 21 Emergency Departments during 3 months in South Korea. We measured TQS(R) and collected the serum with a centrifuge for 5 groups, which was classified with age: 2~10 years (I), 11~20 years (II), 21~30 years (III), 31~40 years (IV), 41~60 years (V), in each hospital. The freezed serum and the protocol with TQS(R) results were taken at the Soonchunhyang University Bucheon hospital to be analyzed. RESULTS: The number of enrolled patients was 1816 (male 58%). The positive rate of TQS(R) was 835 patients (46%), and there was no relation with region or sex. In sex and age, there was a definitive decline in the group III fort males and females. The results of ELISA was showed that 62.8% (> 0.15 IU/ml) and 52.2% (> 0.2 IU/ml) had protective levels of tetanus antibody. The proportion decreased to approximately 43% and 18% among persons 40~60 years of age at each level of antibody titers. By region and population, there was no statistical relationship with TQS(R) and ELISA, but previous military service was associated with a higher prevalence of protective antibodies to tetanus (p<0.001). CONCLUSIONS: A substantial portion of adults in South Korea do not have antibody levels that are protective against tetanus. Also, the mean level of tetanus antibody titers was definitively lower than those of other developed conturies and consistently decreased with aging. Therefore, an adult formulation diphteria and tetanus toxoid every 5 or 10 years is recommended for all adults between 20 and 60 years of age after being tested with TQS(R) in South Korea.

Study of Potential Organ and Tissue Donation in the Emergency Room

BACKGROUND: It is well known that the final treatment for human organ failure is transplantation. However, in reality, the number of donors of organs is insufficient compared to the number of patients waiting for transplantation. Identification of potential organ and tissue donors is important to transplantation. The status of patients having a possibility for transplantation among the patients who visited the emergency room was reviewed, and the status of donations of organs after determination of brain death in the emergency room was reviewed. The present study was performed in order to seek methods of increasing the rate of procurement of organs. METHODS: The records of patients who visited the emergency medical center of the present hospital from January 1, 1998, to December 31, 1999, were retrospectively analyzed. The patients were classified into three groups by interviewing the doctors in charge. Group I were those who were determined to be dead upon arrival at the hospital, Group II were those who left the hospital because of death or who were hospitalized in an irrecoverable state, and Group III were those who were determined to have died during the treatment in the emergency room. RESULTS: The results of this study showed that the number of potential donors of organs among the total 33,783 patients who visited the emergency room during this time was 299 patients, including 91 patients in Group 1, 89 patients in Group 2, and 119 patients in Group 3. Among them, 137 patients were excluded as their ages were not proper, and 62 patients were excluded due to medically unsuitable diseases. The remaining 100 patients were understood to be potential organ-donating patients. Among them, 98 cases were lost as approach to transplantation was not accomplished, and only 2 cases were successful transplantations in the emergency room. The reasons for the deaths of the potential organ donors included 49 cases of trauma, 15 cases of cardiac disease, 8 cases of respiratory disease, 7 cases of cerebral vascular disease, and 11 other cases. CONCLUSION: Most patients that could be determined to be brain dead were lost without recognition of the possibility of transplantation. Although many potential organ-donating patients were seen, the actual rate of procurement of organs was very low. These results imply that it is necessary to have transplantation programs in emergency rooms in order to find patients with possible brain death and to raise the awareness and training of people engaged in medicine and of people in general. Increasing the rate of organ procurement requires that criteria for non-heart-beating donation be established and then applied in the emergency room, bearing in mind the possibility of transplantation from the time of initial treatment as serious patients. The criteria for predicting potential brain death should be prepared for prior to the determination of brain death, as presented by KONOS(Korean Network for Organ Sharing).

The Study of Changes in Arterial Blood Gas Finding with Time Interval

BACKGROUND: Arterial blood gas analysis are highly susceptible to preanalytic error due to improper method of obtaining or handling the blood sample before analysis. The error in measurement of blood gas analysis are loss of CO2 by exposure to atmospheric air, effect of anticoagulant itself, temperature difference between the experimental subject and the measuring electrode and metabolic change which occur between blood sampling and measurement. METHOD: To study the effect of the delay in estimation of blood gas and drawn blood on values of blood gas partial pressure and pH. Blood sample were divided into 2 groups according to the method of storage, group I stored at 24~25degrees C(room temperature) under anaerobic condition. ;group II stored at 0~4degrees C(refrigerator) under anaerobic condition. The samples were analyzed by time interval through 180 minutes in each group. RESULTS: The result were as follows: 1) PaO2 decreased significantly after 10 mins in group I, whereas it decreased significantly after 20 mins in group II. 2) PaO2 increased significantly after 20 mins in group I, whereas it increased significantly after 120 mins in group II. 3) pH decreased significantly after 60 mins in group I, whereas it decreased significantly after 120 mins in group II. 4) No significant changes of bicarbonate and SaO2 were noted in each group CONCLUSION: From above results, it would be advisable to analyze the sample in a short period of time or to store in a refrigerator when the measuring will be delayed. So we highly recommend that blood gas analysis should be performed as soon as possible after sampling, especially within 10 minutes.

The Clinical Study of Vibrio vulnificus Infection Occurred in the Region of the Southwest Coast

BACKGROUND: V. vulnificus infection is found between May and October when the man who has hepatic disorder or immunity disorder eats raw shellfish and it causes the systemic symptoms such as sudden fever, chilling, shock and stupor and local skin lesions like blob and necrosis. This disease has 46~61% of fatality rate in spite of intensive treatment. This study conducts the examination of history, epidemic study, ingesting raw fish and bacteriologic investigation in the patients with similar clinical symptoms to the above and examines the diagnostic correlations. METHOD: It is conducted with 31 cases who admitted at emergency medical center of Chosun University Hospital from May of 1995 to September of 1998 and are suspected to have V. vulnificus infection. It analyze bacteriologic examination, the survey of residence, eating raw shellfish, hepatic disorder, alcohol drinking habits and skin lesion. RESULTS: 1)the rate of male and female is 15.5:1 and in the age, 18 cases are in fifties, seven ale in fifties and six are over sixties. 2) Clinically, V. vulnificus is detected in 20 of 31 cases which is suspected to have V. vulnificus i18c1ion and it is not detected in 5 cases. Other bacteria are detected in 6 cases and they include staphylococcus aureus, pseudomonas species, beta hemotytic streptococcus and E-coil. 3) In local distribution, Kohung has 10 cases, Shinan and Mokpo have six, Haenam and Kangjin have aye, Yongkwang and Muan have five, Naju and Yongam have five and Kwangju has one. 4) Eating fishes and raw shellfishes is found in 31 cases. In the kind of shellfishes, eating raw clam is 10 cases, raw thin-shelled surf calm is 8 cases, raw oyster is 5 cases and sliced raw fish is 4 cases and pickled sea floods ate 4 cases. 5) The cases with hepatic disorder are 23 and 15 Gases with heavy alcohol dunking Carrier are included. The cases with Diabetic Mellitus are four and those with pulmonary tuberculosis are two. Two cases have not basal diseases. 6) On the opinion of skin lesion, 20 cases show vesicular necrosis, 7 cases have dendriform erythema, 3 cases have papule and one case doesn't show clear skin lesion. CONCLUSION: When V. vulnificus infection is detected, it is fatal and those who have hepatic disorder or heavy alcohol drinking habit must avoid eating fishes and shellfishes raw in summer. It is important to have emergency treatment for the patient whose V. vulnificus infection is suspected. It is considered that the administration of initial antibiotics is effective by generalizing the clinical symptom, epidemic opinion and patient history even before the results of bacteriologic confirmed.

Analysis of predictive factors in the Assessment of Mear-drowning in Children

Drowning is the second most common cause of accidental death of children in Korea. But the study of near-drowning is very rare in Korea. The purpose of our study is to determine the factors that may influence survival on the basis of submersion time, consciousness state upon admission to hospital, the kinds of water, laboratory findings and neurological outcomes. The survey was performed by a retrospective cohort study on 28 near drowning victims of less than 15 years of age who were admitted to the emergency room in the Chosun University Hospital between May 1988 & May 1997. The results were as follows 1) Sex distribution was 22 males and 6 females. 2) Submersion time was (5 minutes in 9 cases, 5-9 minutes in 6 cases,10-14 minutes in 5 cases,15-19 minutes in 3 cases, > or =20 minutes in 5 cases. 3) Comatose patients upon arrival were 6/7 cases in the death group(86%) and 2/21 cases in the improved group(10%). they had unfavorable outcomes(P<0.05). 4) The first pH value was mean 7.02)0.12 in the death group and mean 7.31 +/-0.13 in the improved group. there was a statistically significant difference between the death and the improved group(P<0.05). 5) The patients who had increased blood glucose concentration were all 7 cases in the death group and 12/22 cases in the improved group(54%). The mean blood glucose concentration was mean 424.7235.6mg/dl in the death group and mean 140.182.7mg/dl in the improved group. There was a statistically significant difference between the death and the improved group(P<0.05). 6) The patients who had pulmonary edema upon arrival were all 7 cases in the death group and 1/21 cases in the improved group(18%). They had unfavorable outcomes(P<0.05). 7) The patients who had been submerged more than 15 minutes were all 7 cases in the death group and 6/21 cases in the improved group(5%). They had unfavorable outcomes(P<0.05). We conclude that pediatric victims of near-drowning can be assigned to high or low likelihoods of unfavorable outcomes with the use of five variables, comatose mentation upon arrival, decreased initial blood pH, increased initial blood glucose concentration, pulmonary edema, and maximum submersion time estimated longer than fifteen minutes. This prediction rule may be useful if it can be validated in another cohort.

One Case of Quadriplegia Resulted from Cervical Penetration Wound

A case of quadriplegia resulted from cervical penetrating wound was admitted to chosun university hospital intensive care unit, and undergone steroid therapy and antibiotics therapy. On the 6th hospital day, the septic complication was developed and it proved to be bacterial meningitis by CSF examination. Broad spectrum antibiotics was administered immediately after the diagnosis and the patient was monitored carefully. The bacterial meningitis was improved and no other serious complication was developed. The patient was discharged with permanent neurologic deficit, quadriplegia.