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G C Liu

Publications and source records attributed to G C Liu.

83 records · Page 5Linked to original sources
PubMed1976

Measurement of squalene in human tissues and plasma: validation and application.

A method is described for accurate and reproducible measurement of squalene in plasma, feces, urine, bile, and tissue that depends on isolation by alumina column chromatography after mild saponification and on measurement by gas-liquid chromatography. Recoveries from all tissues exceeded 80% and from plasma 96%; losses were accurately corrected by appropriate additions of squalene as an overall recovery standard.

Adult↗
PubMed1975

Measurement of cholesterol synthesis in man by isotope kinetics of squalene.

A method for measuring the rate of total daily cholesterol synthesis in man has been developed through isotope kinetic studies of squalene biosynthesis after intravenous administration of [14C]mevalonic acid. Plasma squalene becomes rapidly labeled, reaching maximal specific activity approximately 100 min after mevalonate administration and then decays exponentially to reach undetectable levels in 12 hr. The rate of daily squalene synthesis equals the percent dose of mevalonate converted to cholesterol divided by the area under the specific activity curve of squalene; the fraction of the dose of mevalonate converted to cholesterol is calculated by the simultaneous injection of [3H]- and [14C] cholesterol in plasma. The premise that squalene and cholesterol synthetic rates are equivalent was tested. In seven patients it was found that the mean daily cholesterol synthesis rates estimated simultaneously by sterol balance and by sqyalene kinetic methods agreed within 8%. In addition, fractional conversions of mevalonic acid to cholesterol were highly correlated with cholesterol synthesis rates. Maximum estimates of the pool sizes and half-lives of metabolically "active" squalene also were obtained. This measurement of daily cholesterol synthesis by squalene kinetics minimizes patient inconvenience, is suitable for outpatient studies, and yields results in 4 weeks or less. Because of the rapidity of the rate of squalene synthesis, the results obtained reflect cholesterol synthesis over a period of less than 10 hr and are therefore uniquely applicable to unsteady state situations.

Adult↗
PubMedDate not supplied

MRI manifestations of gastrointestinal lymphoma.

The magnetic resonance (MR) images of 11 cases of gastrointestinal lymphoma are presented. The findings include irregularly thickened mucosal folds, irregular submucosal infiltration, annular constricting lesion, exophytic tumor growth, mesenteric masses, and mesenteric/retroperitoneal lymphadenopathy. The tumors were homogeneous and intermediate in signal intensity on T1-weighted images. Heterogeneously increased signal intensities were noted on T2-weighted images. There was mild to moderate enhancement after intravenous administration of gadolinium dimeglumine (Gd-DTPA). The submucosal tumor infiltration might be outlined between the strongly GD-DTPA-enhanced mucosa and the low-intensity muscular layer. In one case that received tumor resection, the pathological examination showed destruction of most parts of the muscular layer, and the MR images did not disclose the low-intensity muscular zone.

Adolescent↗
PubMedDate not supplied

MRI demonstration of peritoneal implants.

The magnetic resonance imaging (MRI) findings of 12 proven cases of peritoneal implants, mainly carcinomatosis, were reviewed for evidence of peritoneal seedings. The seeded sites include the pouch of Douglas, the ileocecal and retrocecal regions, the right and left paracolic gutters, Morison's pouch, the right subdiaphragmatic parietal peritoneum, the greater and lesser omentum, the gastrocolic, gastrosplenic, and phrenicocolic ligaments, the small bowel mesentery, the sigmoid and transverse mesocolons, and the small and large bowel walls. Sizes varied from less than 1 cm to omental cake and bulky tumors. The findings include linear or tiny nodular infiltrations of the omentum and subperitoneal fat (ligamentous, mesenteric, and mesocolic), focal or segmental wall thickenings, loss of unilateral colonic haustration with sacculation on the contralateral side, and nodular soft tissue masses along different locations of the peritoneal surfaces. Air was introduced via an antegrade or retrograde method to act as a gastrointestinal contrast agent and was found to be useful for delineating the seedings. As is true with computed tomography scan, miliary implants are also not detectable with MRI. The sensitivity and specificity of MRI in detecting peritoneal implants remain to be determined.

Abdominal Neoplasms↗
PubMedDate not supplied

MRI manifestations of gastrointestinal wall thickening.

The appearance of gastrointestinal wall thickening of various entities is demonstrated on magnetic resonance imaging (MRI). The entities include benign gastric ulcer, gastric carcinoma, pancreatic carcinoma with direct invasion of stomach, duodenal leiomyoma, radiation enteritis, peritonitis, colonic carcinoma, recurrent carcinoma at the gastrojejunal anastomosis with direct extension to the transverse colon, colocolic intussusception, sigmoid diverticulitis with pericolonic abscess and fistula into the urinary bladder, and lymphoma of the stomach, duodenum, small bowel, and colon. Air was introduced antegradedly or retrogradedly into the alimentary tract to act as a contrast agent. When the bowel was distended by air, the normal bowel wall was barely visible or even invisible. Abnormal focal or segmental wall thickening was outlined between the intraluminal air and extraluminal fat. In some instances, the thickenings were better demonstrated on coronal or sagittal sections. The proper muscular layer of the bowel has a low-signal intensity and was delineated between the thickened mucosa-submucosa and extramural fat. Interruption of this low-intensity zone might represent tumor invasion through the muscular layer.

Digestive System↗
PubMedDate not supplied

The diagnostic value of galactography in patients with nipple discharge.

To evaluate preoperative galactographic findings in the differentiation between the benign and malignant lesions in patients presenting spontaneous nipple discharge without mass. Of the 215 patients who have undergone the galactography, 181 cases with abnormal galactography had surgery performed. All galactrograms were reviewed and galactographic findings were correlated to the pathological results to determine diagnostic differentiation. Of the 181 cases we operated on, 112 cases were macroscopically bloody, with 30 cases having cancers (26.8%). Fifty-four cases with serous discharge had seven cancer cases (13.0%). No cancer cases with other color discharge were found. Of the 37 cancer cases, 11 cases had lesions located in the main mammary ducts (lactiferous duct and the segmental duct) (29.7%) and 26 cases had lesions in the peripheral ducts (the subsegmental duct and its branches) (70.3%) (P<.05). Of 113 cases with benign proliferative ductal lesions, 88 cases were located in the main mammary duct (77.9%) and 25 cases in the peripheral mammary duct (22.1%) (P<.05). Otherwise, 29 cancer cases (82.9%) had ductal obstructions and 28 cancer cases (75.7%) had irregular intraductal defects that appeared in the galactograms, which is different from the 113 benign proliferative ductal lesion cases that had 88 cases (71.7%) with ductal dilatation and 90 cases (79.6%) with lobular or smooth intraductal defects (P<.05). These results showed that the cancer cases had a higher rate of locating in the peripheral duct, irregular intraductal duct defects, and ductal obstruction, and a lower rate associated with ductal dilatation or torsion. The galactographic findings were evaluated using the tumor location, types of intraductal defects, ductal obstruction, and dilatation. Preoperative diagnostic galactography is useful in differentiating between the benign or malignant lesions in patients with spontaneous nipple discharge.

Adolescent↗
PubMedDate not supplied

Evaluation of galactography for nipple discharge.

Galactography is useful in the evaluation of spontaneous discharge from the nipple of a nonlactating breast. Without galactography, surgeons have relied on either masectomy or excision of the major duct system responsible for the discharge. From January 1989 to May 1996, 106 galactograms were performed with monofilament polypropylene suture guiding for duct cannulation in 105 cases. The discharge duct was identified by pre-operative galactography, followed by a selective excision of ductal-lobular unit. In all tissue specimens, the cause of the pathologic secretion was found histologically; most often, it was intraductal papilloma (42.6%). In 35.6% of the specimens, findings with a prospective significance (papillomatosis, hyperplasia, carcinoma) were discovered and further operative treatment was initiated. The color of the discharge allowed no prediction of the histological findings. The accuracy of galactography was 88.4%, 84.6%, and 77.4% in papilloma, cancer, and other benign lesions, respectively. It is better than physical examination and other tests. Galactography represents a useful test in the diagnostic workup of secretory breasts.

Adolescent↗
PubMedDate not supplied

Inflammatory/infectious diseases and neoplasms of colon. Evaluation with CT.

The purpose of this study is to review the computed tomography (CT) appearance of infectious and inflammatory diseases, and neoplasms of colon. Forty-five patients with 25 cases of colonic neoplasms and 20 cases of inflammatory and infectious diseases of colon were evaluated based on CT findings of colonic wall thickening (> 5 mm, soft tissue density versus pure wall edema or both), length of the involved segment (short (< or = 5 cm) versus long segment), pericolic infiltration, mesenteric infiltration, lateroconal fascial thickening, mechanical ileus, ascites, contiguous terminal ileum involvement, distribution of the diseased colon, and abscess formation. The results were compared using chi-square test or Fisher's exact test. Our results showed that colonic wall thickening of soft tissue density with or without edema and pure bowel wall edema were the two statistically significant findings in differential diagnosis of colon (p < 0.05). We concluded that CT is a good imaging tool to make differential diagnosis between infectious/ inflammatory diseases and neoplasms.

Adenocarcinoma↗
PubMedDate not supplied

Dynamic contrast-enhanced subtraction and delayed MRI of gastric tumors: radiologic-pathologic correlation.

PURPOSE: Our goal was to determine whether dynamic MR subtraction images could be used to detect and stage gastric tumors. METHOD: Dynamic MR subtraction images were prospectively performed in 20 patients without gastric lesions and in 39 patients with gastric tumors. The flat- or depressed-type early gastric cancers were excluded. The MR findings were assessed for layered pattern of the normal gastric wall, detectability of tumors, enhanced pattern of tumor, and depth of the tumor invasion. Surgical specimens were obtained from 30 of the patients with tumors, and histopathologic sections were made in the dynamic MR scanning direction. RESULTS: The three-layered structure of the normal gastric wall was apparent in more of the dynamic MR subtraction images (60%) than of the nonsubtraction images (30%) in the control group. All 39 gastric tumors were detected by MRI. The intact inner layers overlying stromal tumors and outer layers interrupted by advanced gastric cancers were clear on the subtracted images. MRI accurately T-staged 88% of the gastric cancers. CONCLUSION: Dynamic MR subtraction images can be used to identify gastric tumors and to stage gastric cancers.

Adult↗
PubMedDate not supplied

The Hound of the Baskervilles effect: natural experiment on the influence of psychological stress on timing of death.

OBJECTIVE: To determine whether cardiac mortality is abnormally high on days considered unlucky: Chinese and Japanese people consider the number 4 unlucky, white Americans do not. DESIGN: Examination of cardiac and non-cardiac mortality on and around the fourth of each month in Chinese and Japanese subjects and white controls. SETTING: United States. SUBJECTS: All Chinese and Japanese (n=209 908) and white (n=47 328 762) Americans whose computerised death certificates were recorded between the beginning of January 1973 and the end of December 1998. MAIN OUTCOME MEASURES: Ratio of observed to expected numbers of deaths on the fourth day of the month (expected number was estimated from mortality on other days of the month). RESULTS: Cardiac mortality in Chinese and Japanese people peaked on the fourth of the month. The peak was particularly large for deaths from chronic heart disease (ratio of observed to expected deaths = 1.13, 95% confidence interval 1.06 to 1.21) and still larger for deaths from chronic heart disease in California (1.27, 1.15 to 1.39). Within this group, inpatients showed a particularly large peak on the fourth day(1.45, 1.19 to 1.81). The peak was not followed by a compensatory drop in number of deaths. White controls, matched on age, sex, marital status, hospital status, location, and cause of death, showed no similar peak in cardiac mortality. CONCLUSIONS: Our findings of excess cardiac mortality on "unlucky" days are consistent with the hypothesis that cardiac mortality increases on psychologically stressful occasions. The results are inconsistent with nine other possible explanations for the findings-for example, the fourth day peak does not seem to occur because of changes in the patient's diet, alcohol intake, exercise, or drug regimens.

China↗