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Biomedical subjects

W J Soong

Publications and source records attributed to W J Soong.

At least 19 recordsLinked to original sources

Stability and peptide binding specificity of Btk SH2 domain: molecular basis for X-linked agammaglobulinemia.

X-linked agammaglobulinemia (XLA) is caused by mutations in the Bruton's tyrosine kinase (Btk). The absence of functional Btk leads to failure of B-cell development that incapacitates antibody production in XLA patients leading to recurrent bacterial infections. Btk SH2 domain is essential for phospholipase C-gamma phosphorylation, and mutations in this domain were shown to cause XLA. Recently, the B-cell linker protein (BLNK) was found to interact with the SH2 domain of Btk, and this association is required for the activation of phospholipase C-gamma. However, the molecular basis for the interaction between the Btk SH2 domain and BLNK and the cause of XLA remain unclear. To understand the role of Btk in B-cell development, we have determined the stability and peptide binding affinity of the Btk SH2 domain. Our results indicate that both the structure and stability of Btk SH2 domain closely resemble with other SH2 domains, and it binds with phosphopeptides in the order pYEEI > pYDEP > pYMEM > pYLDL > pYIIP. We expressed the R288Q, R288W, L295P, R307G, R307T, Y334S, Y361C, L369F, and 1370M mutants of the Btk SH2 domain identified from XLA patients and measured their binding affinity with the phosphopeptides. Our studies revealed that mutation of R288 and R307 located in the phosphotyrosine binding site resulted in a more than 200-fold decrease in the peptide binding compared to L295, Y334, Y361, L369, and 1370 mutations in the pY + 3 hydrophobic binding pocket (approximately 3- to 17-folds). Furthermore, mutation of the Tyr residue at the betaD5 position reverses the binding order of Btk SH2 domain to pYIIP > pYLDL > pYDEP > pYMEM > pYEEI. This altered binding behavior of mutant Btk SH2 domain likely leads to XLA.

Agammaglobulinaemia Tyrosine Kinase↗

Intratracheal oxygen administration during bronchoscopy in newborns: comparison between two different weight groups of infants.

BACKGROUND: The development of ultrathin fiberoptic bronchoscopy (FB) has made the examination of neonatal airways a practical possibility. The aim of this study was to assess the effects of intratracheal oxygen (ITO) administration on blood oxygenation and carbon dioxide (CO2) changes during FB in different body-weight infants. METHODS: Newborns suspected of having airway problems, but in a stable cardiopulmonary condition were studied. An ultrathin (outside diameter, 2.2 mm) fiberoptic bronchoscope that was modified by adding an external tube (internal diameter, 0.3 mm; outside diameter, 0.64 mm) to deliver oxygen was used. For ITO administration, a low oxygen flow rate of 0.1 l/kg/min was delivered directly into the trachea. Oxygenation and CO2 measurements were obtained at five different stages: 1) just before FB (baseline); 2) with the tip of the bronchoscope at the supralarynx; 3) with the tip at the carina without ITO; 4) with the tip at the carina with ITO; and 5) 15 minutes after FB. Forty infants were studied completely and divided into two groups according to their body weight: 1) the light-weight group (< 2,500 g), 21 infants; and 2) the heavy-weight group (> or = 2,500 g), 19 infants. RESULTS: In both groups, arterial blood oxyhemoglobin saturation and oxygen tension decreased significantly (p < 0.05) when the tip of the bronchoscope advanced from the nostril to the supralarynx, and further decreased (p < 0.01) when at the carina level. Small infants had greater decrements of both oxygenation measurements (p < 0.05) than the large infants. After ITO administration, both oxygenation measurements increased significantly (p < 0.001) and returned to baseline following FB. Both end tidal pressure of CO2 (P(ET)CO2) and arterial CO2 tension (PaCO2) significantly increased from the baseline when the FB tip was advanced from the supralarynx to the carina (p < 0.05). During ITO administration, the PaCO2 increased (p < 0.01) but the P(ET)CO2 decreased (p < 0.001). After FB, both CO2 measurements returned to baseline. The pH only decreased during ITO administration. CONCLUSIONS: We conclude that FB causes significant hypoxemia and hypercapnia in newborns, especially in underweight infants. Appropriate ITO can be considered a safe and beneficial technique for maintaining oxygenation during FB. P(ET)CO2 monitoring may mask true blood CO2 retention during ITO administration.

Birth Weight↗

High-frequency oscillatory ventilation in premature infants.

BACKGROUND: Although assisted ventilation has reduced the mortality rate of premature infants, pulmonary disease is still the major cause of morbidity and mortality in very low birth weight infants. We designed this study to evaluate the efficacy and safety of high-frequency oscillatory ventilation (HFOV) in premature infants and to compare the outcome for early intervention with HFOV versus conventional ventilation (CV). METHODS: From January, 1997, to June, 1998, we analyzed premature infants with respiratory failure who required mechanical ventilation and supplemental oxygen to support adequate gas exchange in our neonatal intensive care unit. Patients were eligible if their gestational age was less than 35 weeks or their birth weight was less than 1,751 g. A total of 35 neonates were enrolled in the study. Eighteen infants were treated with HFOV, and 17 infants were treated with CV. They were treated with early intervention of HFOV or CV, within 24 hours-of-age. Patients were excluded if a lethal congenital anomaly, bacteremia, hydrops fetalis, congenital diaphragmatic hernia or intubation only for apnea were noted. Data on demographics, gas exchange and outcome parameters were collected for each patient enrolled in the study. RESULTS: No differences were noted in the demographic features between the study groups. All of the enrolled patients suffered from variable grades of respiratory distress syndrome. A significantly shorter intubation period was found in the HFOV group compared with the CV group (2.8 +/- 1.5 days vs 8.8 +/- 9.4 days; p = 0.013). CONCLUSIONS: HFOV is a safe and effective therapy for premature infants with respiratory failure due to respiratory distress syndrome.

Female↗

Coxsackievirus B1 infection in infants less than 2 months of age.

Most of the neonatal enteroviral infections reported in the literature are associated with Coxsackievirus B2-B5 and echovirus 9 and 11. We report a retrospective Coxsackievirus B1 (CB1) infection in infants less than 2 months of age. Seventeen patients had aseptic meningitis and 8 had systemic sepsis (multi-organ involvement including meningitis, impaired liver function, and abnormality in coagulation). The symptoms and signs were nonspecific and could not be distinguished with bacterial infection on clinical grounds. Virus isolation was mandatory for diagnosis. Impaired liver function and coagulation profiles were noted in patients with systemic sepsis, but not in patients with meningitis only. CSF examination showed some uncommon features of viral meningitis: predominance of polymorphonuclear cells (PMN) was noted in 62.5% of patients and hypoglycorrhachia in 64% of patients. The patients with only meningitis recovered completely without any sequela. One of the eight patients with systemic sepsis died with case fatality rate 12.5%. Physicians should be aware of the possibility of CB1 virus infection in young infants during prevalent seasons. Specimens should be sent for viral culture in patients with meningitis and sepsis to make a definite diagnosis.

Age of Onset↗

Symptomatic patent ductus arteriosus in very low birth weight infants.

BACKGROUND: Premature neonatal survival rates have increased significantly. The diagnosis of patent ductus arteriosus (PDA) has also increased. In this paper, we present our experience of incidence, clinical features and outcome of the treatment of symptomatic PDA in very low birth weight infants. METHODS: From January 1990 to December 1995, 181 premature infants with birth weight less than 1,500 g were admitted to the Neonatal Intensive Care Unit (NICU) of Veterans General Hospital-Taipei. Thirty-seven were diagnosed to have symptomatic PDA. By reviewing hospital records, the clinical features and outcome of treatment of these infants were analyzed retrospectively. RESULTS: The incidence of symptomatic PDA was 20.9% and 21.4% in infants with birth weight less than or equal to 1,000 g, 1,001-1,500 g, respectively. The mean age at diagnosis of infants with symptomatic PDA was significantly less than those without symptoms (3.6 +/- 2.9 days vs 9.6 +/- 17.2 days, p = 0.044, 95% CI = 0.2-11.8). With fluid restriction and diuretic therapy, asymptomatic patients had a higher spontaneous ductal closure rate than symptomatic patients (58.3% vs 10.8%, p < 0.001, 95% CI = 17.9-77.1%). Thirty-two (97.0%) infants with symptomatic PDA responded to indomethacin therapy. However, four infants (12.1%) had recurrence. These four infants and a nonresponder received surgical ligation of the PDA and survived. There were four deaths. The reasons for death were respiratory failure in two, sepsis in one and necrotizing enterocolitis with intestinal perforation in one. CONCLUSIONS: Conservative medical management such as fluid restriction and diuretics are often adequate for asymptomatic PDA. However, since symptomatic PDA tends not to close spontaneously, patients should be treated with indomethacin if ductal shunting compromises cardiopulmonary function.

Ductus Arteriosus, Patent↗

Experiences with high-frequency oscillatory ventilation in premature infants with respiratory distress syndrome.

BACKGROUND: High-frequency oscillatory ventilation (HFOV) has been used in treating premature infants with respiratory distress syndrome who have a low incidence of ventilation-associated lung injury. Herein, we report our initial clinical experience in using HFOV to treat such infants. METHODS: From October 1996 to February 1997, 10 premature infants with severe respiratory distress syndrome treated with HFOV were retrospectively evaluated. Clinical course and laboratory data collected during treatment were analyzed. Parameters evaluated included patient survival rate, incidence of chronic lung disease and morbidity associated with HFOV usage. RESULTS: The mean gestational age was 29 +/- 2 weeks; mean birth weight, 1,182 +/- 342 g; and mean period of HFOV treatment, 3.4 +/- 1.9 days. One patient died of sepsis due to infective pancarditis. Two patients developed moderate chronic lung disease at 30 days post delivery and in one of these patients, the disease persisted at 36 weeks' of age. The overall survival rate was 90%. No patient developed air-leak syndrome during the course of treatment. CONCLUSIONS: Our initial experience demonstrated that using HFOV in treating premature infants with severe respiratory distress syndrome was safe and effective. The incidence of moderate to severe chronic lung disease or air-leak syndrome following HFOV was low.

Female↗

Stomach rupture associated with physical struggle in a child.

A 5-year-old girl with spontaneous rupture of the stomach was treated successfully with excision of the ischemic edges of the perforation with primary repair. In this case, vigorous resistance against medical measurement resulted in rupture of the stomach, which was already distended with a large amount of fluid and air. The child survived following immediate surgical intervention and intensive postoperative care.

Child, Preschool↗

The evaluation of percutaneous central venous catheters--a convenient technique in pediatric patients.

OBJECTIVE: To evaluate the feasibility and effectiveness of 3 different types of silastic catheters that were used for percutaneous central venous catheterization (PCVC) through peripheral veins. DESIGN AND SETTING: The study was prospective and consecutive for 6 years at a pediatric/neonatal intensive care unit and pediatric ward in Veterans General Hospital-Taipei, a university-affiliated medical center, in Taiwan, ROC. PARTICIPANTS AND INTERVENTIONS: The patients who had PCVC were consecutively enrolled from January 1988 to December 1993. Three types of silastic catheters were used. The classification was according to the caliber as small catheter (SC, 0.30 mm ID), mid-size catheter (MC, 0.51 mm ID) and large catheter (LC, 0.64 mm ID). The same insertion technique, catheter-through-needle, was used for all PCVC placements through the peripheral vein. After insertion, each catheter was connected to a conventional short cannula (24-, 22-, or 20-gauge) of compatible caliber, and then linked to the infusion system. RESULTS: 1318 PCVCs were used in 1126 consecutive patients, that included 754 SCs in 649 infants (among them 60.9% were less than 1500 g), 383 MCs in 319 toddlers, and 181 LCs in 158 children. Mean (SD) body weight at the time of catheter insertion was SC 1.7(0.9)kg, MC 12.1(6.5)kg and LC 19.3(7.6)kg. Overall, mean (SD) duration of these PCVC was 16.4(8.4) days. A significantly longer duration was noted in: (a) SC group with 19.7(10.4) days than the other two groups [MC 12.4(6.5) days, LC 11.2(5.0) days]; (b) patients with body weight equal to or less than 3.0 kg [18.7(8.6) versus 14.1(6.1); and (c) insertion sites other than external jugular vein (EJV) [18.8(9.7) versus 11.7(6.0)]. These PCVCs provided reliable venous access for multiple purposes such as hyperalimentation, venous access or sampling of blood, antibiotic therapy and chemotherapy. MC and LC were also used for monitoring the central venous pressure. Most of the time, SC and MC were inserted through the superficial peripheral vein of the scalp, neck and extremities, while LC was almost approached via the EJV. The overall success rate of insertion was 92.4% (1318/1427). No significant difference was observed among the different catheter groups [93.4% (754/807) in SC, 90.5% (383/423) in MC and 91.9% (181/197) in LC] and the different insertion sites. Within each group of PCVC, more than eighty percent of catheters were removed electively: 83.3% in SC, 89.6% in MC and 84.5% in LC. Probable catheter-related sepsis accounted for 2.7% (36/1, 318) of all PCVCs. With this study, the cost of each PCVC set is 3.0 US dollar. CONCLUSION: This study indicates that the use of three different calibers of silastic catheter is feasible and effective for PCVC in pediatric practice.

Body Weight↗

The application of a modified mini-flexible-fiberoptic endoscopy in pediatric practice.

BACKGROUND: The application of bronchoscopy in infants and small children is still restricted in most institutions because of their limited airways. The purpose of this study was to evaluate the usefulness of a modified mini (2.1 mm OD) flexible fiberoptic endoscope (FFE) in diagnosis and therapy of suspected pediatric airway problems. METHODS: A prospective two-year study was carried out in a tertiary care neonatal/pediatric intensive care unit and general ward in a children medical center of a university-affiliated hospital. The employed mini-FFE (Machida ENT-30 F III, Tokyo, Japan) was modified with the addition of an external silastic catheter (0.5 mm inward diameter, 0.9 mm outward diameter) for suctioning, oxygen delivery, and medications during study. RESULTS: Totally, 247 laryngoscopies and 212 bronchoscopies were performed in 207 patients without significant morbidity or any associated mortality. The age of patients ranged from 1 day to 10 years. About one-fifth of the procedures (larngoscopy 21.5%, 53/247; bronchoscopy 19.8%, 42/212) were performed in patients under the age of one month. Patient's body weight ranged from 650 g to 40 kg. About fifty-five percent of the procedures (laryngoscopy 55.1% 136/247; bronchoscopy 55.2%, 117/212) were performed in patients weighing less than 5 kg. The most common path of either laryngoscopy (94.3%, 233/247) or bronchoscopy (94.8%, 201/212) was through the nasal route. In 102 patients who had been demonstrated to have upper airway problems, 16 patients (15.7%) also proved to ahve significant lesion(s) below the glottis. CONCLUSIONS: This modified FFE is a safe and a valuable instrument that can serve as an important aid in the diagnosis and therapy as well as a guide for surgical intervention of respiratory tract disorders in small infants and children.

Bronchoscopes↗

The efficacy of different umbilical cord care regimens: an in vitro study on their drying and antimicrobial effect.

BACKGROUND: Topical regimens have been used for umbilical cord care for different purposes, but their drying efficacy has rarely been statistically analyzed. We designed an in vitro study with six regimens to determine which one can achieve the best drying and antimicrobial effects in umbilical cord care. METHODS: Twenty-seven umbilical cords were resected when babies were born. Each cord was cut into seven segments in appropriate length and randomly labeled to seven groups. Six regimens including 75% alcohol, 90% alcohol, tincture povidone-iodine, aqua povidone-iodine, Chinese herbs, and one powder agent (M) were used topically on six groups of umbilical cords once daily. The control group received no treatment. Daily weight of the cords was recorded for 7 days, and bacterial culture was performed on the sixth day. RESULTS: All study groups presented similar algebraic functional relationship between weight change and time. The drying effect occurred mostly within the first 3 days (weight loss 88.6%), especially on the first day (62.1%). Mean ratio of the final weight/initial weight was 10.2%. Significant day-by-day weight loss was noted from day 1 to day 5 (p < 0.001). Both aqua and tincture povidone-iodine groups showed not only satisfied drying effect but also significantly better antimicrobial effect than other groups. CONCLUSIONS: Povidone-iodine has both good drying and antimicrobial effects in umbilical cord care. As the topical use of povidone-iodine has been reported to relate to transient neonatal hypothyroidism, we suggest it to be used only as a good substitute if there are signs of umbilical cord infection.

1-Propanol↗

Non-traumatic injuries in childhood: an epidemiological survey.

BACKGROUND: Accident is the major cause of morbidity and mortality in childhood. The incidence of various non-traumatic injuries has increased due to proliferation of many chemical products and curiosity of little children, which needs our special attention for prevention. METHODS: Two hundred and sixty-six children were sent to the pediatric emergency room of Veterans General Hospital-Taipei from January 1990 to December 1993 with a diagnosis of non-traumatic injuries. Retrospective analysis of their medical records was performed. RESULTS: Household materials were the most common ingested material causing non-traumatic injuries, followed by drugs, foreign bodies and gases. The male to female ratio was 1.3:1. The children were most commonly 1 to 3 years of age (66.2%), especially between 13 to 24 months. Benzodiazepines, pesticides and coins were the most common causes in drug, household material and foreign body groups, respectively. Sixty-two percent of cases had symptoms, and the major presentations occurred in central nervous system. Ninety-two percent of non-traumatic injuries happened at home, and ninety-two percent of the events were accidental. Approximately thirty percent of patients needed hospitalization. Ultimately, two cases died and another three had severe sequelae. CONCLUSIONS: Boys at 1-3 years of age had the highest proportion among young victims of non-traumatic injuries especially via accidental ingestion or poisoning, and home was the most common site of event. Proper prevention with education to the parents and children is of the most importance to eliminate such injuries.

Accidents↗

Hemophilia A presenting with intracranial hemorrhage in neonate: a case report.

Intracranial hemorrhage (ICH) in a neonate is an uncommon presentation of hemophilia. Its occurrence is invariably preceded by mild-to-moderate head injury, unlike adult hemophiliacs in whom ICH occurs without prior head injury in half the cases. The bleeding event may follow a minor injury of labor (eg, prolonged second stage of labor or the use of forceps). In a recent experience at our hospital, a 6 D/O male baby with hemophilia A presenting with ICH after traumatic delivery was later found to have factor VIII deficiency. We suggest that prenatal management for suspected cases should take family history of bleeding disorders and carrier testing into consideration. Any term neonate with ICH should eliminate the possibility of hemophilia until proved otherwise. Some specific diagnostic and therapeutic recommendations to assist the clinician to evaluate an infant with ICH and prolonged PTT are discussed.

Cerebral Hemorrhage↗

Continuous positive airway pressure by nasal prongs in bronchiolitis.

Ten infants with evidence of impending respiratory failure from severe bronchiolitis were successfully treated with continuous positive airway pressure (NCPAP) with double nasal prongs. Their mean (SD) age was 6.7 (3.8) months and mean (SD) body weight was 7.1 (2.1) kg. Respiratory assessments were made immediately before and 2 hours after application of NCPAP. Clinical symptoms, signs, and arterial blood gases improved in all patients, with a significant fall in mean (SD) respiratory rate [71 (6) vs. 54 (9) per minute], mean (SD) heart rate (178(9) vs. 154(15) per minute], and mean (SD) partial pressure of arterial carbon dioxide [Paco2; 48.0 (13.9) vs. 42.4 (12.9) mmHg]. There was a significant rise in mean (SD) arterial blood pH [7.33 (0.05) vs. 7.37 (0.05)] and mean (SD) oxygenation ratio [Fio2/Pao2, 155 (25) vs. 175 (22)]. We believe NCPAP is an effective method, with numerous advantages in the treatment of severe bronchiolitis. Early application of NCPAP is suggested to avoid the need for mechanical ventilation.

Bronchiolitis↗

Hemolytic impact of central venous catheters on fresh whole blood.

An in vitro study was conducted to determine the degree of hemolysis of fresh whole blood, transfused at rates of 10, 20, and 40 ml per hour through three different sizes of central venous catheters by using the same piston-type syringe pump. The catheter lengths were 20 cm, 30 cm and 30 cm; the intraluminal calibers were 0.18 mm, 0.30 mm and 0.51 mm, respectively. A total of 20 healthy volunteers were enrolled as blood donors. Nine 20-ml aliquots of fresh whole blood were obtained from each donor. These samples were assigned to infuse through nine infusion combinations of three different-gauge catheters with each of three different speeds. Three hemolysis parameters which included red blood cell counts, hematocrit and plasma potassium of the effluent were measured and compared with those of the controls (preinfusion). The results showed no significant hemolysis during passage through any infusion system. It was concluded that fresh whole blood may be transfused at regular rates through these three fine-bore central venous catheters without fear of hemolysis.

Blood Transfusion↗