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Biomedical subjects

J M Chang

Publications and source records attributed to J M Chang.

At least 37 records · Page 2Linked to original sources
PubMed2000

Differentiation of obstructive from non-obstructive small bowel dilatation on CT.

PURPOSE: to find a useful decision procedure for the differentiation of obstructive from non-obstructive small bowel (SB) dilatation on the computed tomography (CT). MATERIALS AND METHODS: four criteria were divided into different degrees and evaluated. These include: (A): continuity (non-continuous, continuous); (B): transition zone (absent, gradual, abrupt); (C): prestenotic SB fluid (minimal, about one-fourth, one-half, and three-fourths, nearly complete); and (D): colonic contents (minimal, moderate, considerable). One hundred fifty-three examinations, 86 obstructive and 67 non-obstructive, were analyzed using chi(2)-square tests to determine the relationship of each criterion to the presence of small bowel obstruction (SBO), whether the proportions of various degrees of these criteria differed significantly among the obstructive and non-obstructive subgroups, and to classify the criteria with a tree-based model (calculated by the computer) for the development of a useful decision procedure. RESULTS: in each of the four criteria, the trend of probability of obstruction was statistically significant (P=0.0000). The proportions of most, except two, of the various degrees of different criteria in the obstructive and non-obstructive subgroups differed significantly (P<0.01). The obstruction tends to have a continuou dilatation, an abrupt transition, more prestenotic SB fluids, and less colonic contents. The results of classification by a tree-based model were 76 true-positive, ten false-negative, six false-positive, and 61 true-negative. The sensitivity was 88%; specificity was 91%; positive predictive value was 93%; negative predictive value was 86%; and the overall accuracy was 90%. CONCLUSION: by analyzing the above four criteria together, a useful tree-based model can be developed and utilized as a supplemental decision procedure for the differentiation of obstructive from non-obstructive SB dilatation. The accuracy can be further promoted if the factor of a recognized pathologic condition is taken into consideration.

Decision Trees↗
PubMed2000

In vivo effect of endothelin-1 on plasma calcium and parathyroid hormone concentrations.

We have previously reported an in vitro inhibitory effect of endothelin-1 (ET-1) on parathyroid hormone (PTH) secretion. In the present experiment, ET-1 was infused into rabbits to study the in vivo effect of ET-1 on the changes in calcium, magnesium, PTH and calcitonin concentrations. Femoral arteries and veins of anesthetized male rabbits were cannulated to monitor vital signs, blood sampling and infusion of the agents being studied. Infusion of ET-1 (1, 5, 10 and 20 ng/kg per min) induced a dose-dependent decline in plasma ionized calcium concentrations from 6.68+/-0.26 to 5.50+/-0.46 mg/dl (P<0.05) and a decrease in calcitonin concentrations from 48.6+/-6.5 to 32.5+/-4.7 pg/ml. PTH concentrations increased from 58.3+/-10.2 to 159.4+/-22.1 pg/ml. In a separate experiment, calcium gluconate solution was simultaneously infused to keep calcium concentrations steady, thereby proving a calcium 'clamp'. In normal calcium concentration, ET-1 infusion gradually decreased PTH concentrations from 71.4+/-8.6 to 38.0+/-6.2 pg/ml. We further infused sodium citrate solution to decrease the calcium concentration (2.0 mg/dl less) and calcium gluconate solution was infused to keep calcium concentrations steadily less than normal. PTH concentrations were initially stimulated by the induction of hypocalcemia (68.1+/-11.2 to 135.6+/-8.5 pg/ml), but decreased by ET-1 infusion (135.6+/-8.5 to 85.1+/-15.2 pg/ml). Plasma magnesium concentrations did not change significantly throughout the entire study and calcitonin concentrations were not significantly changed during the calcium clamp studies. Serum phosphate and 1,25-(OH)(2) vitamin D(3) concentrations were also measured, but they also did not change significantly. In conclusion, ET-1 exhibited an in vivo acute hypocalcemic action, independent of calcitonin. It also directly decreased PTH secretion if serum calcium concentrations were kept steady. The above findings are consistent with the results of our previous in vitro experiment.

Animals↗
PubMed2000

High prevalence of selective immunoglobulin A deficiency in peritoneal dialysis patients.

We encountered two hemodialysis (HD) patients with recurrent infections and complete immunoglobulin A deficiency (IgAD). To survey the possibility of a similar occurrence in other populations, we conducted the present study. We used nephelometry to examine the levels of immunoglobulins G (IgG), A (IgA), and M (IgM) in 42 continuous ambulatory peritoneal dialysis (CAPD) patients, 246 HD patients, 56 chronic renal failure (CRF) patients, and 250 normal adults. Four CAPD patients (9.5%) and five HD patients (2.0%) were found to be completely IgA deficient (IgA < 6.67 mg/dL). Peritoneal dialysis patients therefore had a significantly higher prevalence of IgAD compared with HD and CRF patients. The underlying diseases leading to dialysis therapy in the IgAD patients varied. Their dialysis durations also varied. The occurrence rate of peritonitis in CAPD patients with IgAD was no higher than in patients without IgAD. The clinical significance of IgAD was focused on mucosal immunity, but the exact prevalence of infection was difficult to define. However, these patients' medical records did suggest more frequent respiratory tract infections and cellulitis events than did the records of patients without IgAD. Two PD patients with IgAD died of pneumonia. Immunodiffusion and indirect ELISA methods were used to detect the presence of auto-antibodies, successfully identifying them in three patients. Further research is needed to study other mechanisms of IgAD.

Adolescent↗
PubMed1999

The peptide ligands mediating positive selection in the thymus control T cell survival and homeostatic proliferation in the periphery.

Positive selection to self-MHC/peptide complexes has long been viewed as a device for skewing the T cell repertoire toward recognition of foreign peptides presented by self-MHC molecules. Here, we provide evidence for an alternative possibility, namely, that the self-peptides controlling positive selection in the thymus serve to maintain the longevity of mature T cells in the periphery. Surprisingly, when total T cell numbers are reduced, these self-ligands become overtly stimulatory and cause naive T cells to proliferate and undergo homeostatic expansion.

Animals↗
PubMed1999

Short- and long-term uses of calcium acetate do not change hair and serum zinc concentrations in hemodialysis patients.

Calcium acetate (CaAc) acutely decreases absorption of concomitantly administered zinc gluconate (Hwang et al., AJKD 1992), but its long-term effect on zinc metabolism has not been studied. This study is intended to elucidate whether use of CaAc as phosphate binder on a daily basis affects zinc status in hemodialysis (HD) patients. Effects of CaAc on serum zinc were studied in 44 HD patients for 8 weeks (short-term). In 10 of these patients, the changes of serum and hair zinc were followed for 8 months (long-term). The daily dose of CaAc contained 25.35 mmol elemental calcium. Serum and hair zinc concentrations were measured by atomic absorptiometry. Our results were as follows: (i) in the short-term study, serum zinc concentrations did not show a significant difference compared to the baseline; (ii) in the long-term study, serum zinc concentrations showed no significant difference between different time points (11.0+/-0.5 in the beginning, 11.9+/-0.4 after 2 months, 11.4+/-0.4 after 4 months and 11.3+/-0.5 micromol/L after 8 months, n=10). However, these values were all significantly lower than in the normal controls (15.7+/-0.5 micromol/L, n=16); (iii) hair zinc content was not significantly different from the baseline level (2.7+/-0.1 in the beginning, 2.4+/-0.1 after 2 months, 2.6+/-0.2 after 4 months, 3.1+/-0.1 micromol/g hair, and from that of normal controls, 2.7+/-0.2 micromol/g hair). In conclusion, daily application of CaAc does not significantly interfere with zinc absorption and storage in HD patients. However, the comparable hair zinc content in the presence of decreased serum zinc concentrations indicates that the metabolic processing of zinc in HD patients is different from that of normal individuals.

Calcium↗
PubMed1998

Medullary cystic disease: a family study.

Medullary cystic disease of the kidney is characterized by progressive tubulointerstitial disease with medullary cyst formation and secondary glomerular sclerosis. We treated a patient with chronic renal failure and investigated the family history of renal disease. The patient, an 18-year-old woman, was admitted due to poor appetite and fatigue for several months. Findings on physical examination were normal except for a pale conjunctiva. Urinalysis revealed only mild proteinuria with clear sediment. The hemogram showed normocytic normochromic anemia with hemoglobin 86 g/L. The patient was azotemic and her creatinine clearance rate was 10.7 mL/min. Renal sonography showed contraction of both kidneys with a marked increase in cortical echogenicity. One small cyst was found in the medullary area. Computed tomography (CT) and magnetic resonance imaging revealed several medullary cysts. Percutaneous renal biopsy showed focal and periglomerular sclerosis, marked tubular atrophy, and interstitial fibrosis. Ten of her family members were examined for renal function, and by sonography and CT. Five had medullary cysts, and three of the five showed abnormal renal function. Medullary cystic disease should be considered in the differential diagnosis of patients with renal disease and a positive family history.

Adolescent↗
PubMed1998

A patient of primary hyperparathyroidism with full-blown bone changes simulating malignancy.

The two most common causes of hypercalcemia are malignancy and primary hyperparathyroidism (1 degree HPT). The radiographic presentations and the histological findings on bone biopsy are important for differential diagnosis of underlying diseases. We report a patient with hypercalcemia who presented unusual bone manifestations. A 43 y/o woman was admitted due to right femoral fracture. X-ray on the right tibia revealed several osteolytic cystic lesions with sclerotic rims. Blood biochemistry showed anemia, impaired renal function and hypercalcemia. Multiple osteolytic lesions on the skull and bilateral forearms were also noted. Malignancy, such as multiple myeloma or metastatic cancer was suspected. However, this was excluded because of the absence of M-component on serum protein electrophoresis and the negative finding of plasma cells or other malignant cell on bone biopsy examination. Abdominal sonography demonstrated bilateral medullary nephrocalcinosis. The final diagnosis of 1 degree HPT was made, based on the findings of classic pathological pictures (brown tumor) and the markedly elevated intact parathyroid hormone (1267.4 pg/ml) level. Sonography on the neck and 201Tl/99mTc parathyroid subtraction scan localized a left lower parathyroid tumor and fine needle aspiration confirmed the parathyroid origin. Diagnosis of 1 degree HPT could only be made from recurrent urolithiasis and X-ray picture of osteitis fibrosa cystica in the past. This patient presented the full-blown skeletal changes which are uncommonly seen nowadays. The characteristic sclerotic rims suggesting increased bone formation provides a further important clue for differential diagnosis of 1 degree HPT from other malignancies with osteolytic bone lesions.

Adult↗
PubMed1997

Percutaneous transsplenic catheterization of the portal venous system.

PURPOSE: To evaluate the safety and feasibility of transsplenic portal vein catheterization. MATERIAL AND METHODS: Under ultrasonic guidance, percutaneous transsplenic splenic vein catheterization was performed in 17 patients. Two of the patients had minimal and 5 moderate ascites. In 11 patients, the platelet counts were over 50000/mm3 and the coagulation time normal or mildly prolonged, while 6 patients had either platelet counts of less than 50000/mm3 or moderately prolonged coagulation level. RESULTS: Transsplenic portal catheterizations were successfully performed in 16 of the 1/patients (one failed because of small splenic size). Procedure-related complications occurred in 3 patients with 2 requiring one unit of packed RBC transfusion. The third patient accumulated minimal fluid in the left pleural space. Imaging studies within one week of the procedure were made in 8 patients. These examinations revealed an intrasplenic hematoma in 2 patients. One patient had a small amount of hemoperitoneum. No major complications occurred. CONCLUSION: Transsplenic portal venous catheterization is a safe and feasible procedure.

Adult↗
PubMed1997

Treatment of PermCath-related sepsis in uremic patients.

Patients who use PermCath as the vascular access for long-term hemodialysis are occasionally confronted with catheter-related infections. Recently, we have treated 17 patients suffering from PermCath-related sepsis. The clinical presenting features were leukocytosis in 14/17, high fever and shaking chill during dialysis in 12/17, and signs of exit site infection in 3/17. No shock was found. All patients received clinical evaluation to exclude infection sources other than from blood and inside the catheter, such as pulmonary, genitourinary, hepatobiliary and cutaneous systems. Blood drawn from both PermCath and peripheral vein was sent for bacterial culture. Bacterial culture of the blood samples from PermCath revealed Staphylococcus sp. in 7/17, Pseudomonas sp. in 5/17, Enterobacter sp. in 4/17, Streptococcus sp. in 1/17. Fourteen blood samples from peripheral vein showed positive culture results identical to those from PermCath, but negative study were noted in three other patients. The patients were divided into two treatment groups: Group I: systemic antibiotics without PermCath removal in 7, Group II: "locked-in" retention in addition to systemic anti-biotics in 10. Antibiotics were empirically chosen according to bacteriological studies. In the "locked-in" retention treatment, antibiotics were retained into both the inflow and outflow PermCath lumens in the exact volume of each lumen for 24 hours. The antibiotics solutions were replaced on a daily basis. The same antibiotics were also given intravenously. Duration of treatment depended on clinical progression and follow-up blood culture results and ranged between 13 and 24 days. The schedule of dialysis was not changed through the period of PermCath-related sepsis. The sepsis was cured in all group II cases but not in 2 of group I and resulted in mortality in these 2 patients. The PermCaths were preserved in 5/7 in group I with two mortality cases and all except one preserved in group II patients without mortality. We suggested that "locked-in" retention in addition to systemic antibiotics is the treatment of choice for the patients with PermCath-related sepsis. This method also preserves the functional integrity of PermCath, which is the lifeline vascular access of the patients with exhausted native vessels.

Aged↗
PubMed1997

Interaction between extracellular calcium and endothelin-1 influences parathyroid hormone secretion from bovine parathyroid cells through the increase in intracellular calcium.

Endothelin-1 (ET-1) secretion from bovine parathyroid cells (bPTCs) responds to the changes in extracellular calcium concentrations ([Ca2+]c) and ET-1 inhibits parathyroid hormone (PTH) secretion. However, the effect from the interaction between [Ca2+]e and ET-1 on PTH secretion is unknown. To clarify these issues, a bPTC suspension was used to study the regulation of ET-1 secretion by subtle changes in [Ca2+]e and PTH secretion by the interaction between [Ca2+]e and ET-1. We added [Ca2+]e at varying concentrations, 0.5-2.0 mM, to the bPTC medium to define the relationship between [Ca2+]e and ET-1 secretion and found that the ET-1 secretion was inversely regulated by [Ca2+]e with a low [Ca2+]e stimulating, and a high [Ca2+]e inhibiting ET-1 secretion. It is even suppressed to an undetectable level at a [Ca2+]e of > 1.5 mM. Further, we worked to determine how the interaction between ET-1 and [Ca2+]e influences PTH secretion. ET-1 > or = 10(-10) M, inhibited PTH secretion in a dose-dependent manner and significantly inhibited PTH secretion at a low or normal [Ca2+]e. At an ET-1 concentration of > or = 10(-10) M, the 'calcium-PTH' relation showed significant changes in physiological responses. The effect of ET-1 on intracellular calcium concentrations ([Ca2+]i) of bPTCs was studied using the fura 2 fluorescence method. We found that increasing doses of ET-1 induced a progressive increase in [Ca2+]i of bPTCs. Our results suggest that ET-1 secretion is inversely regulated by [Ca2+]e. ET-1 can inhibit PTH secretion and alter the parathyroid secretion pattern to various calcium stimuli. ET-1 also elevates [Ca2+]i and this may be a part of the intracellular signaling mechanisms involved in the inhibition of PTH secretion from bPTCs.

Animals↗
PubMed1997

Intravenous repletion of phosphorus deficiency in the chronic renal failure patients with severe hypophosphatemia.

Severe hypophosphatemia is a potentially life-threatening medical condition and might lead to a fatal outcome in critically ill patients. The situation is further complicated by the co-morbid renal failure. We evaluated the efficacy and safety of the intravenous phosphate repletion in 15 renal failure patients with severe hypophosphatemia. Six patients with advanced renal failure and nine patients under maintenance hemodialysis, 7 males and 8 females, aged between 42 and 83 years old, were found to have serum phosphate level < 1.2 mg/dL from various medical conditions and were treated with intravenous phosphate infusion. The phosphate solution prepared from sodium dihydrogen phosphate (NaH2PO4), containing 13 mg/ml phosphate and 0.5 meq/ml sodium, in the dosage 2.5-3.0 mg phosphate/Kg body weight, was administered through the central venous lins every 6-8 hours. The infusion was discontinued once serum phosphate level reached 5.0-5.5 mg/dL. Serum ionized calcium, phosphate and intact parathyroid hormone levels were serially followed at different intervals, respectively. The hemodialyzed uremic patients received their dialysis treatment as scheduled. All patients survived the hypophosphatemic period and regained normal phosphate levels after repletion. The amount of phosphate administered to reach the target level ranged between 3438 and 9150 mg and the duration of treatment varied between six and seventeen days. Hypocalcemia (< 4.2 mg/dL) was noted at eight occasions during the whole treatment period but none was symptomatic. Eleven patients recovered from the offending illness. However, four patients expired due to reasons not directly consequent to and temporally remote from hypophosphatemia. We conclude that prompt repletion of severe hypophosphatemia and phosphate deficiency with relatively slower rate of NaH2PO4 solution intravenous infusion is a safe and effective mode of treatment for renal failure and uremic patients. The longer treatment period allowed the administered minerals full equilibration. The risk of hyperkalemia is avoided and the sodium/volume load can be eliminated by dialysis.

Adult↗
PubMed1997

Peritoneoscintigraphy using Tc-99m MAA for diagnosis of diaphragmatic disruption in a peritoneal dialysis patient.

Massive hydrothorax is an infrequent but well-recognized complication of continuous ambulatory peritoneal dialysis (CAPD), and is often regarded as a contraindication to its use. We describe here a patient with massive hydrothorax that appeared during CAPD. Peritoneoscintigraphy was performed to demonstrate the clinical suspicion of a pleuroperitoneal communication and the pleurodesis using tetracycline was commenced and this allowed the successful continuance of CAPD.

Female↗
PubMed1996

Azygos blood flow in cirrhosis: measurement with MR imaging and correlation with variceal hemorrhage.

PURPOSE: To evaluate magnetic resonance (MR) measurement of azygos blood flow (ABF) in assessment of risk of variceal hemorrhage in cirrhosis. MATERIALS AND METHODS: ABF in 50 patients with cirrhosis and 20 healthy control subjects was evaluated with phase-contrast cine MR imaging at the transaxial subcarinal plane. Group 1 included nine patients with cervical-drainage varices draining into brachiocephalic vein; group 2 included 41 patients with varices draining into azygos vein and was subdivided as group 2A, 15 patients with variceal hemorrhage, and group 2B, 26 without variceal hemorrhage. RESULTS: Azygos flow rate and velocity were increased in patients compared with that in control subjects. ABF in group 2A was faster than that in group 2B (cutoff, 15 cm/sec; sensitivity, 80%; specificity, 89%). Group 1 had ABF close to that of group 2B, but variceal hemorrhage occurred in seven of nine patients in group 1 versus 15 of 41 patients in group 2 (78% vs 37%; P = .029). CONCLUSION: Patients with cirrhosis with cervical-drainage varices or ABF greater than 15 cm/sec may have higher risk for variceal hemorrhage.

Azygos Vein↗
PubMed1996

Major causes of diabetic death at one hospital.

Death certificates filed between 1987 and 1990 at the Kaohsiung Medical College Hospital (KMCH) were reviewed to investigate causes of diabetic death. During this period, 1,383 patients expired at KMCH, of which 151 had diabetes mellitus. The major causes of death in these 151 diabetic patients were infection in 25.8%, cardiovascular disease in 18.5%, cerebrovascular disease in 11.3%, uremia in 8.6% and diabetic ketoacidosis in 1.3%, while diabetes was reported as the contributory or underlying cause of death. Malignancy in 12.0%, liver disease in 5.3%, trauma in 1.3% and upper gastroenteral bleeding in 0.7%, likewise, were among the leading causes of death irrespective of underlying diabetes. However, cause of death in 15.2% of these diabetic patients was undetermined. Our analysis revealed that infection and cardiocerebrovascular disease were the leading problems contributing to diabetic death. Therefore, reducing the risk of infection by strict glycemic control, intensive medical intervention in infection and the proper prevention of diabetic angiopathy-related risk factors and complications are imperative for the reduction of diabetic mortality in our patients.

Cardiovascular Diseases↗
PubMed1996

CT and MRI findings of eclampsia and their correlation with neurologic symptoms.

BACKGROUND: To evaluate the brain lesions of eight eclamptic patients with computed tomogram (CT) and magnetic resonance imaging (MRI) and correlate their radiologic lesions with the neurologic symptoms. METHODS: We recorded and followed up the neurologic presentations of eight eclamptic patients. They received brain CT and MRI the first two days after the development of seizures, then follow-up study of the brain lesions with MRI. Correlation of their radiologic brain lesions with neurologic presentations was also done. RESULTS: Radiologic studies of these patients showed hypoxic-ischemic brain lesions and brain edema involving the temporo-parieto-occipital junctions; these lesions were bilateral and relatively symmetrical in distribution. Other involved regions of the brain included the basal ganglia, periventricular white matter, internal and external capsules and scattered lesions involving various lobes. Almost all the radiologic brain lesions had had total resolution in the follow-up MRI study. Besides generalized tonic-clonic seizure, the other neurologic presentations included headache, blurred vision, and dizziness. CONCLUSIONS: Although the brain lesions involved many regions, the temporo-parieto-occipital junction is the most frequently involved area. The incidence of appearance of brain lesions in radiologic study is greatly affected by the temporal relationship of the scan to the development of seizure. Visual disturbance and headache have a good correlation with radiologic findings, i.e. occipital lobe involvement and diffuse brain edema, respectively. However, some of the other neurologic presentations do not have comparable radiologic lesions.

Adolescent↗
PubMed1996

Experience with transjugular intrahepatic portosystemic shunts for gastroesophageal variceal bleeding.

BACKGROUND: Variceal bleeding is a major life-threatening complication of cirrhosis of the liver. Transjugular intrahepatic portosystemic shunts (TIPS) have been accepted as an effective method for portal decompression. Experiences here with the use of TIPS for control of gastroesophageal variceal bleeding is presented. METHODS: Sixteen TIPS procedures were performed for 15 patients who suffered from intractable gastroesophageal variceal bleeding. Nine cases (60%) were hepatitis-related cirrhosis of liver, four (27%) were alcoholic liver cirrhosis and two were cryptogenic in origin. Liver function tests revealed four patients were Child-Pugh's classification A, five were B and six, C. Twelve cases had received failed endoscopic management of varices; and one patient had recurrent variceal bleeding after devascularization. TIPS procedure was performed electively in nine cases and, as an emergency in six cases. RESULTS: Fifteen of the 16 TIPS procedures attempted were successfully performed. The technically successful rate was 94% (15/16), but two cases with successful TIPS procedure expired at the end of the procedure from hypovolemic shock and acute respiratory distress, respectively; thus the completely successful rate was 81% (13/16), The initial bleeding control rate was 83% (5/6) for the six patients with active bleeding. Portal venous pressure was significantly decreased from 30.8 +/- 5.8 mmHg before TIPS to 21.7 +/- 6.0 mmHg after the procedure (P < 0.01) and the porto-systemic pressure gradient also significantly decreased from 23.0 +/- 3.6 mmHg to 11.9 +/- 2.7 mmHg after TIPS (P < 0.01). Recurrent variceal bleeding was noted in four patients (33%) and that was managed by percutaneous transluminal angioplasty (PTA) of shunt, placement of additional stent, second TIPS procedure and a devascularization operation. Hepatic encephalopathy was noted in three patients (25%) after TIPS. CONCLUSIONS: TIPS is an effective method to control variceal bleeding caused by portal hypertension, especially when endoscopic or surgical management has failed or is contraindicated.

Adult↗