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Biomedical subjects

M K Chen

Publications and source records attributed to M K Chen.

At least 37 records · Page 2Linked to original sources
PubMed1997

Infradiaphragmatic extralobar pulmonary sequestration masquerading as an intra-abdominal, suprarenal mass.

Three infants were found to have infradiaphragmatic masses by prenatal ultrasound. Postnatal imaging studies confirmed the presence of these masses, which were suspected of being intra-abdominal malignancies (neuroblastoma). The other principal differential diagnosis was extralobar pulmonary sequestration (EPS). Intraoperative findings were consistent with EPS, which was confirmed by histologic examination. We present these three infants, review the literature, and discuss the evaluation and treatment of infradiaphragmatic EPS.

Abdominal Neoplasms↗
PubMed1997

Perinatal management of enteric duplication cysts of the tongue.

Intra-oral enteric duplication cysts are rare. We recently treated two infants with prenatally diagnosed large sublingual enteric duplication cysts. Antenatal aspiration of the cyst was attempted in one infant without success. Because of the potential for airway obstruction and respiratory distress at delivery, preparation for an immediate tracheostomy was made in case oral intubation was impossible. Fortunately, aspiration of the cyst provided adequate access to the oropharynx for intubation in both infants. The placental cord was not divided until the airway was secured to minimize the potential for anoxic injury. Complete excision of the cyst was subsequently done in one patient. The other infant had an initial marsupialization and laser ablation of the cyst mucosa but the cyst recurred. Cyst excision at 9 months of age resolved the problem. Pathological examination revealed columnar-lined mucosa consistent with enteric duplication cysts. An enteric duplication cyst may present as a large sublingual mass with potential for airway obstruction in the newborn infant. Antenatal diagnosis allows for the proper preparation of personnel and equipment in the management of these neonates during delivery. If the airway is compromised, aspiration of the cyst can be done to improve the access to the oropharynx for intubation. Preparation for emergent tracheostomy should be done before delivery in case oral intubation is not possible. Subsequent complete cyst excision is the treatment of choice.

Airway Obstruction↗
PubMed1997

Laparoscopic common duct exploration in a child with recurrent pancreatitis due to a primary fungus ball in the terminal common bile duct.

We report on a case of a fungus ball obstructing the distal common bile duct and causing recurrent pancreatitis in an otherwise healthy 3-year-old boy. Laparoscopic exploration of the common bile duct was performed using a 10 french rigid fiberoptic cystoscope and a Dormia basket. This is the first example of a primary fungus ball in common bile duct presenting as a pancreatitis and treated laparoscopically.

Acute Disease↗
PubMed1996

Laparoscopic evaluation and treatment of intestinal malrotation in infants.

Infants with intestinal malrotation present with bilious emesis and the diagnosis is generally obtained by an upper gastrointestinal barium study. Malrotation is suspected if the ligament of Treitz is not positioned to the left of the vertebral body. Barium enema may also be used to detect malrotation by noting the abnormal position of the cecum from its usual placement in the right lower quadrant, but this study is not as reliable due to the mobility of the cecum. Some infants may not have classic radiographic findings for malrotation, yet the contrast studies are not entirely normal. We recently treated two infants with recurrent vomiting whose UGI studies suggested intestinal malrotation. Laparoscopic exploration confirmed the diagnosis of malrotation. Laparoscopic correction (Ladd's procedure) of malrotation was carried out in one infant. The second infant underwent a traditional Ladd's procedure. The technique of laparoscopic Ladd's procedure is described. Laparoscopy may be used for the diagnosis and treatment of infants with intestinal malrotation. It may be especially helpful to verify the diagnosis in patients who do not have classic radiographic findings. Whether laparoscopy should be used in patients with midgut volvulus is debatable. Laparoscopic derotation of the volvulus in a setting where the bowel is markedly distended may be difficult and dangerous.

Female↗
PubMed1996

Complications of minimal-access surgery in children.

Minimal-access surgery (MAS) is rapidly becoming the surgical approach of choice for a variety of surgical disorders in adults, but its use in children remains a relative novelty. Most pediatric surgeons continue to harbor justifiable concerns about the morbidity of this modality owing to the cumbersome nature of the instruments and the technical difficulty associated with two-dimensional views. The purpose of this study was to determine the complication rate and the lessons learned from the use of MAS in performing a variety of procedures in a large series of children. To determine complications, the authors reviewed the medical records of all children (n = 636; age range, 1 month to 19 years) who underwent laparoscopy (LAP) or thoracoscopy (THO) during a 5-year period (January 1, 1990 through December 31, 1994). The follow-up ranged from 1 week to 45 months. THO was performed in 62 children. Conversion to thoracotomy occurred in eight children (13%), because of inability to localize the lesion (3), unresectibility (2), inadequate tissue sample (1), unsafe access (1), hypoxemia (1), or inadvertent esophagotomy (1). Postoperatively, two ventilator-dependent children had tension pneumothorax after lung resection and required chest tubes. LAP was performed on 574 children, with conversion to laparotomy occurring in 15 (2.6%), because of technical reasons (10) or intraoperative complications (5). The complication rate of LAP was 2% (12 of 574). Early in the experience, intraoperative complications that led to laparotomy included hemorrhage during appendectomy (2), cholecystectomy (1), and splenectomy (1); and esophagotomy during a fundoplication (1). Other technical problems in the postoperative period were a malpositioned Nissen fundoplication and a gastric volvulus after gastrostomy and Nissen fundoplication owing to improper gastrostomy tube position. In addition, two children had a hernia at the umbilical trocar site that had been used for contralateral inguinal exploration, and cellulitis developed in three patients when a gastrostomy tube was brought out through a trocar site. Other complications not specific to MAS included pelvic abscess after appendectomy (5); small bowel obstruction after jejunostomy catheter placement (1) and combined cholecystectomy/appendectomy (1); enterocolitis (1) and severe hyponatremia (1) after pull-through for Hirschsprung's disease; and pneumonia after splenectomy (1). The overall complication rate of MAS was 4% (26 of 626), and there were no deaths. The initial use of MAS was associated with technical errors, which decreased with experience. Based on this study, the authors recommend (1) routine placement of a thoracostomy tube in children after THO if they require postoperative ventilator support; (2) using the open hernia sac to place a 70 degrees telescope for contralateral inguinal exploration; and (3) not using a trocar site for gastrostomy tube placement in immune-suppressed patients. With appropriate training and experience, MAS can be used safely in children, for a wide variety of diseases, with minimal morbidity and mortality.

Adolescent↗
PubMed1996

Tracheal hamartoma: report of a child with a neck mass.

Tracheal hamartoma represents an oddity in children. Only one case was found in the English literature as a distal tracheal intraluminal lesion causing obstructive symptoms. All other reported cases were in older patients, who were presumed to have asthma or chronic obstructive pulmonary disease. The authors report on a 21-month-old girl who presented with an anterior neck mass fixed to the trachea. Imaging studies showed a lesion (2.5 x 2.3 x 1.7 cm) anterior to the right lobe of the thyroid, extending to the trachea posteriorly and down to the thoracic inlet inferiorly. The mass had a mixture of soft tissue densities with a focus of calcification. Results of thyroid studies were normal, and there was no adenopathy. Neck exploration showed a white, firm, lobulated mass fixed to the trachea, which was resected completely. The postoperative course was unremarkable. Histological studies showed a mixture of mature cartilage, fat, fibroconnective tissue, and spindle cells with myxoid degeneration, consistent with tracheal hamartoma. Based on a literature search, this is the first reported case of extraluminal tracheal hamartoma presenting as a neck mass in a pediatric patient.

Female↗
PubMed1995

The use of minimal access surgery in pediatric trauma: a preliminary report.

Minimal access surgery (MAS) is becoming an accepted modality in the management of adult trauma, but its use in children is rarely reported. Recently, we began using minimal access surgery to evaluate injured children. The purpose of this report is to review our preliminary experience with the use of laparoscopy and thoracoscopy in blunt and penetrating pediatric trauma. Eight children aged 2-14 years old were evaluated using MAS. Two children with blunt injuries had persistent abdominal pain despite normal radiologic studies. Laparoscopy documented a disrupted gallbladder and a small bowel perforation. Laparoscopy was also used to evaluate five hemodynamically stable children with penetrating wounds to the abdominal wall with potential peritoneal penetration. Only one child was converted to a laparotomy. Four were found to have either tangential penetrating wounds or nonbleeding solid organ injuries and were spared an open exploration. Two children with penetrating trauma with potential mediastinal injury were assessed with thoracoscopy. MAS was also used as a therapeutic modality in two children who had diaphragmatic lacerations repaired with an endoscopic "hernia" stapler. MAS accurately identified all injuries. All children were subsequently discharged without complications. We conclude that MAS is a safe and effective way to evaluate and manage hemodynamically stable children with both penetrating and blunt traumatic injuries.

Adolescent↗
PubMed1993

Influence of progressive tumor growth on glutamine metabolism in skeletal muscle and kidney.

OBJECTIVE: The effects of progressive malignant growth on glutamine metabolism in skeletal muscle and in kidney were investigated. SUMMARY BACKGROUND DATA: Fast-growing tumors consume considerable quantities of glutamine and lead to a decrease in circulating glutamine concentrations. METHODS: Experiments were performed at various stages of tumor growth in rats implanted subcutaneously with the non-metastasizing methylcholanthrene-induced (MCA) fibrosarcoma and in pair-fed non tumor-bearing controls. RESULTS: Tumor growth stimulated a twofold increase in hindquarter (muscle) glutamine release, which was not due to an increase in blood flow, but rather to a doubling in the fractional release rate. Consequently, a progressive decrease in skeletal muscle glutamine concentrations was observed over time. Simultaneously, the activity of glutamine synthetase (GS), the principal enzyme of de novo glutamine biosynthesis, increased more than twofold. This increase in muscle GS activity was accompanied by an increase in GS mRNA but the augmentation in GS expression apparently could not match the increased rate of efflux since muscle depletion developed. In rats with large tumors and severe glutamine depletion, GS activity was not elevated. Glutamine feeding increased muscle glutamine concentrations and glutamine synthetase specific activity. Although tumor growth led to the development of mild systemic acidemia, the classic renal adaptations normally observed, i.e., elevated glutaminase activity and accelerated renal glutamine utilization, were not present in acidotic tumor-bearing rats. Instead, renal GS activity was increased in tumor-bearing animals and ammoniagenesis was enhanced, in spite of a reduction in net renal glutamine uptake. CONCLUSIONS: These data suggest that marked alterations in muscle and renal glutamine handling occur in the host with cancer; the enhanced muscle glutamine release in conjunction with no increase in renal consumption is consistent with increased glutamine uptake in other organs, most likely the tumor itself and the liver.

Ammonia↗
PubMed1992

Cytokine regulation of intestinal glutamine utilization.

The effects of cytokines on intestinal glutamine metabolism were studied to gain further insight into the regulation of altered glutamine metabolism that occurs during severe infection. One hundred thirteen adult rats were given a single dose of interleukin-1 (IL-1, 50 micrograms/kg), tumor necrosis factor (TNF, 50 micrograms/kg or 150 micrograms/kg), or saline (controls), and flux studies were performed 4 or 12 hours later. Intestinal blood flow was not different between control and cytokine-treated animals at either time point. At the 4-hour time point, arterial glutamine fell by 16% to 21% in the cytokine-treated animals (p less than 0.05); at the 12-hour time point, the arterial glutamine concentration had returned to normal. Intestinal glutamine extraction decreased in the animals treated with IL-1 at both time points (4 hours: 13% +/- 1.3% in IL-1 versus 20% +/- 1.6% in controls, p less than 0.05; and 12 hours: 9% +/- 2% in IL-1 versus 17% +/- 2% in controls, p less than 0.05). Consequently, net intestinal glutamine uptake fell in the animals treated with IL-1 at both time points (p less than 0.05). Similarly, the activity of mucosal glutaminase, the principal enzyme of glutamine hydrolysis in the gut, fell by 50% in the 4-hour study (6.1 +/- 0.6 mumol/h/mg protein in IL-1 versus 9.6 +/- 0.8 mumol/h/mg protein in controls, p less than 0.01) and by 40% in the 12-hour study (5.4 +/- 0.5 mumol/h/mg protein in IL-1 versus 8.8 +/- 0.4 mumol/h/mg protein in controls, p less than 0.05). Concomitant with the aforementioned decrease in gut glutamine metabolism was a 25% incidence of positive blood cultures for gram-negative organisms in IL-1 treated rats studied at the 12-hour time point (p = 0.05 versus controls). In the doses administered and at the time points studied, TNF had no effects on the parameters of gut glutamine metabolism examined. The results indicate that IL-1 is a potential mediator of the alterations in gut glutamine metabolism observed in sepsis and endotoxemia.

Animals↗
PubMed1992

Mechanisms of accelerated hepatic glutamine efflux in the tumour-bearing rat.

The mechanisms potentially controlling the net release of glutamine by the liver that occurs in tumour-bearing rats were investigated. Studies were undertaken when the tumour comprised approximately 7% (15 +/- 2 g) of total body weight. Hepatic glutamine gradient ratios were calculated by dividing hepatic glutamine content by arterial blood glutamine concentration. Both sodium-dependent and sodium-independent hepatocyte carrier-mediated glutamine transport were evaluated employing hepatic plasma membrane vesicles (HPMVs). In TBR the hepatic glutamine gradient ratio doubled (P < 0.001) secondary to a 52% increase in hepatic content (P < 0.005) and a 16% decrease in circulating glutamine (P < 0.001). Sodium-dependent glutamine transport was increased in HPMVs from TBR secondary to a 24 +/- 4% increase in the maximal velocity of transport (Vmax; P < 0.01) without alteration in apparent transporter affinity (Km). Saturable sodium-independent carrier-mediated glutamine transport was increased in HPMVs from TBR over CONT to a much greater relative degree owing to a 2.7-fold increase in transport Vmax (P < 0.05) without a change in transport Km. The accelerated hepatic efflux of glutamine which characterizes malignant growth appears to be the result of both mass-action gradient phenomena and alterations at the level of hepatocyte membrane transport activity.

Animals↗
PubMed1992

Adaptive regulation in skeletal muscle glutamine metabolism in endotoxin-treated rats.

The effects of a single dose of endotoxin (7.5 mg/kg BW) on skeletal muscle glutamine metabolism were studied in vivo in rats to gain further understanding of the altered glutamine metabolism that characterizes sepsis and other catabolic diseases. In endotoxin-treated animals the arterial glutamine concentration fell early initially and then increased compared with control values. Twelve hours after treatment, the arteriovenous concentration difference for glutamine across the hindquarter doubled, resulting in a significant increase in net muscle glutamine release in endotoxin-treated rats. As a consequence, the muscle glutamine concentration fell in the endotoxin-treated animals by 25%-40%, an event that was apparent as early as two hours after endotoxin treatment. Skeletal muscle glutaminase activity, the major enzyme of glutamine breakdown, was unchanged by endotoxemia, but expression of glutamine synthetase mRNA and glutamine synthetase specific activity increased in a time-dependent fashion. The glutamine depletion that develops in skeletal muscle during endotoxemia is caused by accelerated muscle glutamine release rather than an increase in intracellular degradation or a fall in intracellular biosynthesis. The adaptive increase in glutamine synthetase expression that occurs requires de novo RNA and protein synthesis and may be designed to prevent complete depletion of the intracellular glutamine pool.

Adaptation, Physiological↗
PubMed1991

Endotoxin and renal glutamine metabolism.

The effect of endotoxin on renal glutamine metabolism and ammoniagenesis was investigated in vivo in the rat to gain further insight into the altered glutamine flow that characterizes critical illness. Studies were done 15 hours following a single dose of Escherichia coli lipopolysaccharide (10 mg/kg). Renal blood flow and arterial glutamine concentration were similar in control and study rats, but the kidney switched from an organ of slight glutamine uptake in controls (129 +/- 52 nmol/100 g of body weight per minute) to net release in the endotoxin-treated animals (-273 +/- 170 nmol/100 g of body weight per minute). Simultaneously, the specific activity of renal glutamine synthetase increased by almost 50% (374 +/- 40 nmol/mg of protein per hour in rats given endotoxin vs 253 +/- 12 nmol/mg of protein per hour in controls), while glutaminase was unchanged. Urinary ammonia excretion was reduced by 35% in the endotoxin-treated animals (47 +/- 6 mumol/12 h in endotoxin-treated animals vs 70 +/- 8 mumol/12 h in controls) despite a 10% fall in the arterial bicarbonate value. Endotoxin alters the net flux of glutamine across the kidney which appears to be partially regulated enzymatically. This may impair the kidneys' ability to maintain acid/base homeostasis.

Ammonia↗
PubMed1991

The effects of endotoxin on the splanchnic metabolism of glutamine and related substrates.

The effects of endotoxemia on glutamine metabolism by the splanchnic bed was studied in vivo in adult rats 12 hours following administration of E. coli LPS. Glutamine uptake by the portal-drained viscera fell in the endotoxin-treated animals while glucose uptake doubled. Simultaneously, hepatic glutamine uptake increased ten-fold owing to both an increase in hepatic blood flow and glutamine extraction from the bloodstream. Hepatic alanine uptake, oxygen consumption, and glucose release were also accelerated in endotoxemic rats. The increase in liver glutamine utilization was associated with increases in parenchymal DNA and glutathione levels and an increase in glutathione and urea release into the systemic circulation. This marked increase in metabolic activity occurred in animals with chemical evidence of hepatocellular injury and histologic evidence of hepatocyte necrosis. During endotoxemia the liver becomes the major organ of glutamine consumption. This accelerated utilization provides carbons for energy and gluconeogenesis, nitrogen for ureagenesis, and substrate for nucleotide and glutathione biosynthesis in order to support cell repair and detoxification reactions.

Alanine↗
PubMed1991

Glutamine metabolism by the endotoxin-injured lung.

The alterations in lung glutamine (GLN) metabolism that occurs in the endotoxin-injured lung were studied in rats and subsequently correlated with flux changes that occur in patients with the adult respiratory distress syndrome (ARDS). Measurements in animals were made at various time-points following the administration of endotoxin, while studies in surgical patients were done in a group of healthy controls, in patients with "early" sepsis who had normal chest x-ray films, and in patients with radiographic and physiologic evidence of ARDS. In healthy control rats, net amounts of GLN are released by the lungs into the systemic circulation. This release rate doubled 30 minutes after intravenous endotoxin (1,580 +/- 320 nmol GLN/100 g BW/min vs. 736 +/- 179 in controls, p less than 0.01) but glutamine synthetase activity was unchanged, suggesting an outpouring of cellular glutamine stores. Two hours after endotoxin treatment, this accelerated fractional release of glutamine by the lungs was no longer detected. By the 12-hour time-point, the lungs reversed to an organ of net glutamine balance (234 +/- 248 nmol/100 g BW/min, p less than 0.05 vs. controls and ENDO30 min) despite a more than two-fold increase in glutamine synthetase activity (p less than 0.01). Simultaneously, lung weights were increased by 21% (p less than 0.01) and histologic examination showed an interstitial infiltrate and pulmonary edema. Similar observations were made in humans; patients with "early" sepsis exhibited a marked increase in lung glutamine release, while patients with ARDS demonstrated glutamine balance across the lungs (4,030 +/- 910 nmol GLN/kg BW/min vs. 637 +/- 496 in ARDS, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Nutritional support of the surgical oncology patient.

Malnutrition is a common manifestation of cancer patients and has a significant negative impact on treatment and survival. The metabolic aberrations associated with tumor growth are complex, and nutritional repletion cannot always be accomplished with nutritional support. Ultimate survival depends upon the primary lesion. Oral nutrition should be used whenever patients can eat and are able to take in sufficient calories. Preoperative total parenteral nutrition (TPN) in well-nourished patients appears to be unwarranted at this time, but the efficacy of preoperative TPN in malnourished surgical patients is established. Patients undergoing radiotherapy and chemotherapy can also benefit from nutritional support when the appropriate patient population is selected. In patients who have a potentially treatable disease, their malnourished state should not be a contraindication to therapy, and every effort should be made to nutritionally support such patients.

Cachexia↗
PubMed1991

Survey on use of antimicrobial agents and bacterial resistance in Huashan Hospital.

A cross-section study was carried out to assess the general patterns in use of antimicrobial agents and the trends of bacterial resistance in Huashan Hospital. Of 2,400 patients whose charts were reviewed, 61% were given such drugs. 3,596 antibiotic courses were prescribed. Gentamicin was most frequently used. Results of the susceptibility test of 320 bacterial strains showed a high percentage of resistance against gentamicin, ampicillin, and chloramphenicol. Our findings suggest that antibiotic policies in the hospital need reappraising.

Adolescent↗
PubMed1986

The epidemiology of self-perceived fatigue among adults.

Psychological and other factors are examined individually and collectively in relation to self-perceived chronic fatigue among a national sample of adults. It is found that the lifestyle variable physical activity and such psychological variables as self-reported depression, anxiety, and emotional stress are highly associated with fatigue and are independently predictive of it. Adults who are physically inactive or who experience any psychological problems are at much higher risk of feeling fatigue than those who are physically active or free from psychological problems. Women are more likely to feel fatigued than men, and heavier women are more likely to feel fatigue than lighter ones. No difference in degree of fatigue was found between heavier and lighter men.

Adult↗