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Biomedical subjects

K C Li

Publications and source records attributed to K C Li.

At least 19 recordsLinked to original sources
PubMed2002

Cervical intraepithelial neoplasia is associated with increased polyamine oxidase and diamine oxidase concentrations in cervical mucus.

OBJECTIVE: The aim of this study was to establish whether reactive oxygen species, generated during oxidation of amines, catalyzed by polyamine oxidase (PAO) and diamine oxidase (DAO) in cervical secretions may play a role in the etiology of cervical cancer. METHODS: Cervical mucus was obtained from women attending the gynecological outpatient department: 139 with and 154 without cytological evidence of cervical intraepithelial neoplasia were recruited. The mucus was freeze dried in liquid nitrogen, weighed, and later resuspended for assay of PAO and DAO concentrations using a chemiluminescence method. The two groups were compared by group sequential analysis using PEST3 software. RESULTS: Patients with a colposcopic diagnosis of a high-grade squamous intraepithelial lesion (SIL) had significantly higher enzyme activities than control cases (L(N)PAO 1.37 (0.37) versus 1.18 (0.35): Student t test: P < 0.001; L(N)DAO 1.37 (0.36) versus 1.15 (0.37): Student t test: P < 0.001). CONCLUSION: It is probable that this rise in enzyme activity precedes cytological changes and plays some part in the etiology of cervical cancer, as the cells that undergo premalignant change are normally squamous in origin, whereas mucus is a product of columnar epithelium. Higher enzyme activity in patients with SIL than in controls may be a reflection of higher risk of exposure to amine substrates in semen through multiple sexual partners.

Amine Oxidase (Copper-Containing)↗
PubMed2001

Validation of in vivo MR measurement of oxygen saturation after resuscitation with a hemoglobin-based oxygen carrier in a rabbit model.

RATIONALE AND OBJECTIVES: The authors tested whether noninvasive magnetic resonance (MR) oximetry is accurate in the in vivo measurement of oxygen saturation in a stroma-free, hemoglobin-based oxygen carrier (HBOC). MATERIALS AND METHODS: A central venous catheter was placed in the inferior vena cava (IVC) of 10 New Zealand white rabbits (weight range, 2.5-3.2 kg). Each rabbit underwent removal of 20% of blood volume followed by resuscitation with 10 mL/kg of bovine HBOC-200. Oxygen saturation of the blood mixture was measured in vivo at the IVC with MR oximetry, with separate in vitro calibration for each animal. Blood drawn from the IVC was measured with ex vivo oximetry, which was used as the standard of reference. The in vivo and ex vivo measurements were compared. RESULTS: There was no significant difference (P > .1) between measurements obtained with MR oximetry and ex vivo oximetry. The results with in vivo MR oximetry demonstrated excellent correlation with those from ex vivo oximetry (r = 0.99) over a wide range of physiologic oxygen saturation values (16.7%-74.9%) in venous blood. CONCLUSION: Noninvasive in vivo MR measurement of oxygen saturation is valid for whole blood mixed with stroma-free hemoglobin. Therefore, MR oximetry may be clinically useful for assessing the oxygenation status in patients resuscitated with a HBOC.

Animals↗
PubMed2000

Involvement of spinal protein kinase C in induction and maintenance of both persistent spontaneous flinching reflex and contralateral heat hyperalgesia induced by subcutaneous bee venom in the conscious rat.

To further study the roles of spinal protein kinase C (PKC) in induction and maintenance of both the persistent spontaneous nociception and the contralateral heat hyperalgesia induced by subcutaneous (s.c.) bee venom injection, the effects of intrathecal (i.t.) treatment with a PKC inhibitor, chelerythrine chloride (CH), were evaluated in conscious rats. Pre-treatment i.t. with CH at three doses of 0.01, 0.1 and 1 nmol produced a dose-dependent suppressive effect on the flinching reflex with the inhibitory rates of 39, 48 and 59%, respectively, when compared with the pre-saline control group. Post-treatment i.t. with the drug at the highest dose used (1 nmol) also resulted in a 42% suppression of the flinching reflex compared with the control. Moreover, pre-treatment i.t. with CH at three doses of 0.01, 0.1 and 1 nmol also produced 12, 22 and 48% inhibition of the contralateral heat hyperalgesia in the pre-saline control group. Post-treatment i.t. with the drug at the highest dose used (1 nmol) also resulted in a 35% reversal effect on the established contralateral heat hyperalgesia. The present result suggests that activation of PKC in the spinal cord contributes to the induction and maintenance of both peripherally-dependent persistent spontaneous pain and contralateral heat hyperalgesia which is dependent upon central sensitization.

Animals↗
PubMed2000

ICAM-1 expression in autoimmune encephalitis visualized using magnetic resonance imaging.

The expression of leukocyte adhesion molecules in the intact brains of mice with experimental autoimmune encephalitis (EAE) was visualized by Magnetic Resonance Imaging (MRI) through the use of a new, target-specific MR contrast agent. Antibody-conjugated paramagnetic liposomes (ACPLs) were designed to achieve in vivo targeting of molecules expressed on vascular endothelium, while providing sufficient signal enhancement at these sites for detection by MRI. ACPLs targeted to intercellular adhesion molecule-1 (ICAM-1), an endothelial leukocyte receptor upregulated on cerebral microvasculature during EAE, were administered to diseased mice. Fluorescence microscopy confirmed that fluorescently-tagged ACPLs were localized to central nervous system (CNS) microvasculature in a pattern consistent with ICAM-1 upregulation described immunohistochemically. High resolution MRI of mouse brains ex vivo demonstrated that ACPL binding conferred significant enhancement of signal intensity (SI) as compared to control images. These results suggest that ACPLs can be used as MRI contrast agents to visualize specific molecules expressed on vascular endothelium during disease.

Animals↗
PubMed2000

The clinical value of ferric ammonium citrate: a positive oral contrast agent for T1-weighted MR imaging of the upper abdomen.

This study was undertaken to determine whether ferric ammonium citrate (FAC), a positive magnetic resonance (MR) contrast agent, is of clinical value in demonstrating or excluding pathology of the upper gastrointestinal tract. A retrospective review was performed of pre- and post-FAC studies of MR examinations in 203 patients from phase II and III clinical trials in whom final diagnoses had been established based on the results of biopsy, surgery, or independent imaging procedures. Two independent reviewers made randomized and blinded assessments of the stomach, duodenum, and pancreas. FAC significantly increased the certainty of diagnosis for normal studies of the stomach and duodenum for both readers (P < 0.001) and for abnormal studies of the stomach for one reader (P = 0.004). FAC also significantly increased the certainty of diagnosis for normal pancreas for one reader (P < 0.001). FAC significantly (P < 0.001) increased accuracy and specificity for diagnoses involving the stomach and duodenum for both readers and for one reader for the pancreas. There was significant improvement in sensitivity for gastric diagnoses (P = 0.013) for one reader but not for the duodenum or pancreas. We conclude that FAC is helpful in demonstrating and excluding upper gastrointestinal pathology on MR.

Administration, Oral↗
PubMed1999

Power Doppler imaging of acute renal transplant rejection.

PURPOSE: We evaluated the usefulness of power Doppler imaging (PDI) in diagnosing acute renal-transplant rejection. METHODS: Twenty-eight patients underwent 33 renal-transplant biopsies for suspected acute rejection. Patterns of renal parenchymal vascularity revealed by PDI in patients with abnormal biopsy results were compared with patterns in a group who had normal biopsy results. PDI examinations were reviewed retrospectively by 2 independent radiologists who had no knowledge of the biopsy results. A PDI diagnosis of acute rejection required marked vascular pruning in both the cortex and medulla. PDI results then were compared with transplant-biopsy results. RESULTS: The sensitivity and specificity of PDI for diagnosing acute renal-transplant rejection were 40% and 100%, respectively. None of the patients with negative biopsy results had PDI abnormalities. The negative predictive value of PDI was 33%, and the positive predictive value was 100%. CONCLUSIONS: In our study, an abnormal sonogram was highly predictive of acute transplant rejection. However, a normal sonogram did not exclude the possibility of rejection.

Acute Disease↗
PubMed1999

Differentiation of hepatic malignancies from hemangiomas and cysts by T2 relaxation times: early experience with multiply refocused four-echo imaging at 1.5 T.

The purpose of this study was to examine hepatic lesions with a sequence designed to yield improved T2 measurements and evaluate the clinical utility of these measurements in distinguishing malignant from benign disease. Using a modified Carr-Purcell sequence incorporating features designed to compensate for imperfections in the imaging system, including a train of refocusing pulses emitted in an MLEV pattern oriented in composite fashion along all three coordinate axes, and a single spatially selective pulse placed immediately before a spiral readout, 14 benign lesions and 13 malignant lesions were evaluated prospectively with a conventional 1.5 T imager. The maximum, minimum, and mean T2 values of malignant lesions, hemangiomas, and cysts exceeded corresponding published values from spin-echo and echoplanar studies. The mean T2 value of the malignant lesions differed significantly (P < 0.0001) from those of hemangiomas and cysts. All malignant lesions and all benign lesions were distinguishable by their T2 values, which had ranges of no greater than 118.6 msec and no less than 134.3 msec, respectively. This early experience suggests that improved T2 measurements can facilitate the differentiation of hepatic malignancies from hemangiomas and cysts.

Carcinoma, Hepatocellular↗
PubMed1999

In vivo flow-independent T2 measurements of superior mesenteric vein blood in diagnosis of chronic mesenteric ischemia: a preliminary evaluation.

RATIONALE AND OBJECTIVES: The authors attempted to determine whether the T2 relaxation time of superior mesenteric vein (SMV) blood would decrease in patients with chronic mesenteric ischemia after a meal. MATERIALS AND METHODS: Thirty-two patients without chronic mesenteric ischemia and eight patients with symptomatic chronic mesenteric ischemia underwent magnetic resonance (MR) imaging. All examinations were performed with a 1.5-T unit, a modified Carr-Purcell-Meiboom-Gill sequence, final section-selective pulse of 180 degrees, and spiral readout gradients. Measurements of SMV blood T2 were obtained after at least 6 hours of fasting and 15 and 35 minutes after ingestion of 240 mL of a liquid nutritional supplement. Maximal change of the SMV blood T2 was expressed as a percentage of the fasting T2 in all patients. RESULTS: In control patients, SMV blood T2 increased postprandially by 9.4% +/- 1.3 (95% confidence level; range, 6.8%-11.9%) (data range, -7.3% to 25.6%) compared with fasting T2. In symptomatic patients, SMV blood T2 decreased postprandially by 15.8% +/- 2.2 (95% confidence level; range, -20.1% to -10.7%) (data range, -7.9% to -25.3%). The difference between the two groups was statistically significant (P < .0001 by Student unpaired t test). CONCLUSION: Measurement of SMV blood T2 is a promising test for chronic mesenteric ischemia diagnosis. Therefore, conversion of T2 measurements to estimate oxygen saturation may not be necessary for all cases of this clinical indication.

Adult↗
PubMed1999

Advances in imaging techniques for the diagnosis of focal hepatic lesions.

In the past few years, tremendous advances have been made in the fields of ultrasound, computed tomography, magnetic resonance imaging and contrast agent development. The purpose of this article is to highlight the important developments in imaging techniques that can be used for detection and characterization of focal hepatic lesions.

Aged↗
PubMed1999

New approaches to the investigation of focal hepatic lesions.

In the past few years, tremendous advances have been made in the fields of magnetic resonance imaging, computed tomography and ultrasonography. These include the development of novel contrast agents and new approaches to image acquisition and processing. This review provides an overview of the state-of-the-art of imaging investigation of focal hepatic lesions and highlights some of the most exciting emerging technologies.

Diagnosis, Differential↗
PubMed1999

A comprehensive approach using MR imaging to diagnose acute segmental mesenteric ischemia in a porcine model.

OBJECTIVE: Acute mesenteric ischemia is a lethal disease that lacks a noninvasive diagnostic test. We evaluated the abilities of contrast-enhanced MR angiography, MR oximetry, and real-time interactive MR imaging to diagnose segmental mesenteric ischemia in a porcine model. MATERIALS AND METHODS: Segmental mesenteric ischemia was created by subselective Gelfoam embolization of the mesenteric circulation in eight pigs. Conventional digital subtraction angiography (DSA), MR oximetry, and real-time interactive MR imaging of the small bowel were performed before and after embolization. Changes in the perfusion pattern seen on DSA established the regions of true ischemia. Postembolization DSA and MR angiography were compared with this gold standard. RESULTS: Both MR angiography and DSA had high sensitivity (91% and 100%, respectively) for detecting ischemic regions. The difference was not statistically significant (p > .2). MR angiography yielded lower specificity than DSA (80% and 90%, respectively; p < .01). After embolization, the oxygen saturation in the superior mesenteric vein (SMV) dropped significantly (p < .005). After embolization, the SMV also showed oxygen saturation significantly lower than that in the inferior vena cava (p < .005). In two of the animals, segmental hypomotility of the small bowel was observed. CONCLUSION: MR oximetry is capable of detecting oxygen desaturation caused by segmental ischemia. A loss of oxygen saturation in the SMV relative to that in the inferior vena cava provides a convenient marker of mesenteric ischemia. Contrast-enhanced MR angiography has sensitivity and specificity approaching those of DSA. Both MR techniques hold promise for the detection of acute mesenteric ischemia.

Angiography, Digital Subtraction↗
PubMed1999

Effects of formalin on bacterial growth in mink feed, feed consumption and reproductive performance of adult mink, and growth of mink kits.

Feed that is typically used on commercial mink ranches is an ideal environment for bacterial growth because of the raw animal by-products used as ingredients. Recently, formaldehyde was approved for use as an antimicrobial agent in poultry feed. Experiments in our laboratory were carried out to investigate the effects of incorporating different concentrations of formalin into the feed of mink on the growth of gram-negative and gram-positive bacteria. Feed containing 0, 550 or 1100 ppm formalin was kept refrigerated for up to 7 d and the number of colony forming units of gram-negative and gram-positive bacteria derived from the feed was determined each day. Colony forming units in the formalin-treated feed were significantly fewer than colony forming units in untreated feed. In the second trial, feed containing the same concentrations of formalin was maintained at 30 C for 24 h and cultured bacterial colonies were counted at 0, 12 or 24 h of feed incubation. Both concentrations of formalin were effective in significantly reducing the number of colony forming units. A feed consumption trial determined if mink (Mustela vison) preferred formalin-treated feed to non-treated feed kept refrigerated for up to 7 d. Consumption of feed treated with 1100 ppm formalin was significantly lower than consumption of the non-treated feed on d 1, 2, 4 and 5, but body weight was not affected. A long-term feeding trial determined the effects of formalin on mink reproduction, early growth of offspring and quality of fur. Mink were fed formalin at concentrations of 0, 550 or 1100 ppm for approximately 140 d beginning 1 mo prior to mating until kits were weaned at 6 w of age. Mating success was not affected by consumption of formalin-treated diets, but kit survival at birth was adversely affected in mink consuming 1100 ppm formalin. Hemoglobin concentration, hematocrit, mean corpuscular volume, and mean corpuscular hemoglobin were significantly decreased in 6-w-old kits, but there were no significant differences in any of these parameters between the kits exposed to 0 and 550 ppm formalin. In a second phase, some kits and their dams were continued on their respective dietary treatments from weaning through pelting (approximately 220 and 320 d, respectively). At pelting, hematocrits and hemoglobin concentrations for the kits fed 1100 ppm formalin were significantly less compared to the control and 550 ppm formalin groups. There were no significant differences in body weights among female kits or adult female mink. The body weights of male kits in the 1100 ppm formalin group became significantly less than the body weights of male kits in the control and 550 ppm formalin groups as the trial progressed. The quality of fur was highest for mink in the control group and lowest for mink in the 1100 ppm formalin group. While dietary 1100 and 550 ppm formalin were effective in suppressing bacterial growth in the feed of mink, the deleterious effects of 1100 ppm formalin on kit survival, hematologic parameters, body weight, and quality of fur preclude formalin use at this concentration.

Animal Feed↗
PubMed1999

Adequacy and pitfalls of G6PD deficiency counseling in Hong Kong.

Glucose-6-Phosphate-Dehydrogenase (G6PD) deficiency is common in Hong Kong with an incidence of 4.5% in male and 0.36% in female (Lo et al. 1996).The Neonatal Screening Unit of Clinical Genetic Service started its territory-wide neonatal screening program for G6PD deficiency and congenital hypothyroidism in 1984 (Lam et al, 1986). Because of insufficient manpower and resource, we have been giving health counseling on the phone to parents of G6PD deficient babies and then refer them to nearby maternal and child health centres for monitoring of jaundice. The disease, mode of inheritance, recurrence risk and the precaution against certain medicines (Chan 1996) and chemicals are explained. The purpose (Lam, 1994) is to reassure the parents that their G6PD deficient babies can be as normal as everyone and that they can have normal life. Nevertheless, it has not been established whether telephone counseling has any effect on the affected family in the form of psychological trauma (Marteau, 1989; Fyro, 1987; Li et al, 1996) or significant influence on the decision on future reproduction. This study tried to evaluate the service from the parents' point of view by 1) gathering information on parents' awareness and perception of G6PD deficiency, 2) determination of parents' attitude towards the telephone counseling, and 3) finding out the effect of G6PD deficiency on parents' decision on future reproduction. Over 300 parents were contacted by telephone, and were asked to respond to questions on a questionnaire . The telephone interview focused on parents' understanding of G6PD deficiency, their attitude towards this disease and the possible effect on future reproduction decision. Results showed that over 90% of cases that we had counseled attended the maternal and child health centres. Most of them accepted the presence of G6PD deficiency in their family which did not affect their decision on future pregnancy. Telephone counseling failed to establish a helping relationship with the parent as face to face counseling was more personal. The findings revealed that though telephone counseling had its shortcoming it served the target group effectively. Telephone counseling is still the method of choice for the G6PD deficiency counseling in this locality.

Adolescent↗
PubMed1998

Detection of tumor angiogenesis in vivo by alphaVbeta3-targeted magnetic resonance imaging.

Angiogenesis, the formation of new blood vessels, is a requirement for malignant tumor growth and metastasis. In the absence of angiogenesis, local tumor expansion is suppressed at a few millimeters and cells lack routes for distant hematogenous spread. Clinical studies have demonstrated that the degree of angiogenesis is correlated with the malignant potential of several cancers, including breast cancer and malignant melanoma. Moreover, the expression of a specific angiogenesis marker, the endothelial integrin alphaVbeta3, has been shown to correlate with tumor grade. However, studies of tumor angiogenesis such as these have generally relied on invasive procedures, adequate tissue sampling and meticulous estimation of histologic microvessel density. In the present report, we describe a novel approach to detecting angiogenesis in vivo using magnetic resonance imaging (MRI) and a paramagnetic contrast agent targeted to endothelial alphaVbeta3 via the LM609 monoclonal antibody. This approach provided enhanced and detailed imaging of rabbit carcinomas by directly targeting paramagnetic agents to the angiogenic vasculature. In addition, angiogenic 'hot spots' not seen by standard MRI were detected. Our strategy for MR imaging of alphaVbeta3 thus represents a non-invasive means to assess the growth and malignant phenotype of tumors.

Animals↗
PubMed1998

Description of Songshupsylla, a new subgenus of Macrostylophora (Siphonaptera: Ceratophyllidae), with a discussion of its species groups.

The new subgenus Songshupsylla is erected to include certain species heretofore included in Macrostylophora s. lat. Ewing, 1929. The subgenus is further divided into 2 species groups according to their morphological characters and geographical distribution in the Paleartic and Oriental Regions. Brief descriptions of these species groups and the names of the Chinese taxa are given.

Animals↗