Biomedical subjects

K Lim

Publications and source records attributed to K Lim.

At least 19 recordsLinked to original sources

PubMed1997

The use of augmented-pressure colostography in imperforate anus.

Colostomy is recommended in most newborns with imperforate anus (IA), except those with low-type anorectal malformations (ARM). Accurate demonstration of the anatomy of any associated fistula between the rectum and the urogenital tract is essential for optimal surgical management. Augmented-pressure distal colostography is recommended to fulfill this requirement prior to definitive surgical repair of IA. We examined 12 cases of high or intermediate-type ARM using this technique, which clearly demonstrated the distal perineal anatomy. All were confirmed at posterior sagittal anorectoplasty.

Anal Canal↗

PubMed1997

The pattern of cytokine mRNA expression in ovarian endometriomata.

Intraovarian cytokines play a pivotal role in the normal growth and development of the ovarian follicle. The purpose of this study was to investigate the pattern of cytokine mRNA expression in ovarian endometriomata. A total of 10 patients with histologically confirmed endometriomata undergoing surgery formed the study group while nine patients undergoing sterilization with no evidence of a cyst in the ovary formed the control group. Biopsies of the ovary were obtained at surgery and stored in liquid nitrogen until processed by reverse transcription-polymerase chain reaction amplification to identify the presence of mRNA for interleukin (IL)-1, IL-2, IL-4, IL-6, IL-8, IL-10, IL-13, tumour necrosis factor-alpha (TNF-alpha), and interferon-gamma (IFN-gamma). IL-6 and IL-10 mRNA were expressed by nine and seven patients respectively in the endometriosis group compared with three and one patients in the control group; this difference was significant (P < 0.05). IL-1 alpha mRNA was expressed by seven of 10 patients with endometriosis but by only one of the control group; this was again significantly different (P < 0.04). Ovarian IL-2 and IL-4 mRNA were not expressed in either group. There was no significant difference in the expression of IL-8, IL-13, IFN-gamma and TNF-alpha mRNA in the two groups. These findings suggest that abnormal local expression of certain cytokines may contribute to the development of endometriomata.

Adult↗

PubMed1997

Evaluation of the reliability of computed tomographic criteria used in the diagnosis of round atelectasis.

The purpose of this controlled study was to determine the diagnostic accuracy of computed tomography (CT) in the diagnosis of round atelectasis (RA). We reviewed two groups of chest CT scans of 22 patients (with 24 masses). Group 1 scans represent 10 patients (12 masses) known to have RA, and Group 2 scans represent 12 patients with "RA look-alike" masses. Scans in both groups were selected for review by two of the authors and later independently reviewed by the other authors, who were blind to the actual diagnosis. Scans were rated for the presence/absence of 18 features ascribed to RA in the literature and assigned a percent probability of RA by each rater. Consensus was achieved for discordant ratings, and the individual percent probabilities were averaged to create a consensus probability. ROC curve analysis of the consensus percent probability showed that diagnostic accuracy significantly exceeded chance [area under curve (AUC) = 0.95, p < 0.001]. Of all the features of RA examined, the presence of converging bronchovascular markings discriminated best between RA and "RA look-alikes" (sensitivity 83%, specificity 92%, likelihood ratio 11). Presence of adjacent pleural thickening and pleural-based location were even more sensitive features of RA (100% each), but lacked specificity (33 and 67%, respectively; likelihood ratios 3 and 1.5, respectively). We conclude that (a) although the diagnostic accuracy of CT for RA was high in this series, radiographic diagnosis is imperfect and that (b) the presence of converging bronchovascular markings was the best discriminator between the two groups, but that no single CT feature permitted perfect discrimination.

Aged↗

PubMed1997

Dietary red pepper ingestion increases carbohydrate oxidation at rest and during exercise in runners.

The effects of dietary hot red pepper on energy metabolism at rest and during exercise were examined in long distance male runners 18-23 yr of age. A standardized meal was given on the evening prior to the experiment. The subjects had a meal (2720 kJ) with or without 10 g of hot red pepper for breakfast. During rest (2.5 h after meal) and exercise (pedaling for 1 h at 150 W, about 60% VO2max, using cycling ergometry), expired gasses and venous blood were collected. The meal with hot red pepper significantly elevated respiratory quotient and blood lactate levels at rest and during exercise. Oxygen consumption at rest was slightly but nonsignificantly higher in the hot red pepper meal at 30 min after the meal. Plasma epinephrine and norepinephrine levels were significantly higher in those who had only hot red pepper at 30 min after the meal. These results suggest that hot red pepper ingestion stimulates carbohydrate oxidation at rest and during exercise.

Adolescent↗

PubMed1997

Surgical treatment of breast cancer in New South Wales 1991, 1992.

BACKGROUND: The purpose of this study was to examine existing data on women diagnosed with breast cancer in New South Wales in 1991 and 1992 and to describe surgical treatments received on an inpatient basis. METHODS: Analyses were based on the linkage of two databases: the New South Wales Central Cancer Registry and the New South Wales Health Department's Inpatient Statistics Collection. Data were limited to women who were resident and treated in New South Wales. Main analyses were restricted to definitive surgical procedures. RESULTS: Thirty-six per cent of women treated surgically for breast cancer in 1991 had breast-conserving therapy. This had increased to 39% in 1992. There were substantial geographical variations in the use of breast-conserving therapy in New South Wales which could not be explained by patient characteristics. Age, degree of spread at diagnosis, and area health service/ health region were all found to have an independent association with the probability of having a mastectomy. CONCLUSIONS: Women with a localized degree of spread living in non-metropolitan areas (Health Regions) were almost twice as likely to have a mastectomy as compared with similar women who were resident in metropolitan areas (Area Health Services). The concentration of radiotherapy services may have contributed to the urban/rural variation in breast-conserving therapy in New South Wales, but it is also likely that some of the variations that were observed may be a reflection of the failure of clinicians to use best current practice.

Adult↗

PubMed1996

IL-16 inhibition of CD3-dependent lymphocyte activation and proliferation.

We have recently described the cDNA and predicted protein structure of a natural soluble CD4 ligand, IL-16. IL-16 is chemotactic for CD4+ T cells and induces functional IL-2 receptors in CD4+ T cells. The binding of IL-16 to CD4 results in activation of p56(lck), whose adaptor function is essential for the chemotactic response. Subsequently, increases in intracellular Ca2+ and phosphatidylinositol 1,4,5-trisphosphate occur, as does translocation of protein kinase C from cytosol to membrane. Because of the similarities between these signals and functions and those noted for the CD4 ligand HIV-1 gp120, we investigated the potential regulatory effects of IL-16 on CD3/TCR-mediated lymphocyte activation. Preincubation of human T cells with IL-16 up to 24 h before activation with plate-bound anti-CD3 Abs reduced T cell activation by 80%, as monitored by IL-2R expression and [3H]thymidine uptake. If IL-16 was added following anti-CD3 activation, no suppression was noted. The suppressive effects of preincubation with IL-16 were not rescued by the addition of rIL-2 and were not the result of priming for anti-CD3-induced apoptosis. In addition, IL-16 had no effect on surface expression of CD3 or CD4. However, IL-16 did reduce the magnitude of the anti-CD3-induced intracellular Ca2+ increase. These studies indicate that while the interaction of CD4 with its natural ligand, IL-16, results in Ag-independent chemotaxis and IL-2R expression, this pro-inflammatory state is associated with subsequent transient inhibition of responsiveness via the CD3/TCR complex.

Apoptosis↗

PubMed1996

Effect of O-glycosylated mucin on invasion and metastasis of HM7 human colon cancer cells.

Mucinous colorectal cancers have a poorer prognosis than colorectal cancers which produce a low amount of mucin, but the exact mechanism is not well understood. The present study was undertaken to elucidate the possible mechanisms of invasion and metastasis of colon cancer cells producing high levels of mucin using mucin glycosylation inhibitor, benzyl-alpha-N-acetylgalactosamine. The binding activity of treated HM7 cells to endothelial leukocyte adhesion molecule (ELAM-1) was significantly decreased and fixed cell binding of MoAb SNH-3 and 19-9 (specific for sialyl Le(x) and sialyl Le(a), respectively) was also significantly decreased. Metalloproteinase activity in conditioned medium and invasion of matrigel-coated porous filters by treated HM7 cells were decreased. However, there was no difference between control and treated HM7 cells in terms of matrix protein binding. These results suggest that O-glycosylated mucin is important in the invasive and metastatic properties of HM7 human colon cancer cells.

Acetylgalactosamine↗

PubMed1996

Pronase-based assay method for O6-methylguanine-DNA methyltransferase.

A new, simple, and rapid assay method for O6-methylguanine-DNA methyltransferase (MGMT) has been developed. When [methyl-3H] DNA radiolabeled with N-[methyl-3H]-N-nitrosourea was incubated together with tissue homogenate, [methyl-3H] group was transferred to the enzyme, forming S-[methyl-3H]cysteine. In contrast to the previous methods which determined the amount of [methyl-3H] group removed from [methyl-3H] DNA, the present method measured the amount of [methyl-3H] transferred to the enzyme. This has been done by hydrolyzing the radiolabeled enzyme with pronase which is a proteolytic enzyme with a broad substrate specificity. On pronase digestion, [methyl-3H]-labeled enzyme becomes soluble in trichloroacetic acid. The method is very simple and rapid, and the only expensive equipment required is a scintillation counter which is a relatively routine piece of equipment at present. More than a dozen samples can be processed within 4-5 h without any difficulty. This new method has been employed in the studies on organ distribution of MGMT of rat and mouse.

Animals↗

PubMed1996

Glucocorticoid regulation of androgen binding protein expression in primary Sertoli cell cultures from rats.

Glucocorticoids are known to inhibit testicular function, and its receptor is also localized in the Sertoli cells. To evaluate possible role of glucocorticoid in Sertoli cells, the effects of dexamethasone on the expression of androgen binding protein (ABP) have been investigated in primary Sertoli cell cultures. Dexamethasone increased ABP mRNA levels, with maximal stimulation reached at 36 hr. The induction of ABP mRNA was dependent on the low concentration (10(-8) and 10(-7) M) of dexamethasone but gradually reduced in the cells treated with high concentration (10(-6) and 10(-5) M). Dexamethasone-induced ABP mRNA level was no change in the cells after addition of cycloheximide but almost reduced by actinomycin-D pretreatment. Steady-state levels of ABP mRNA gradually increased in the Sertoli cells prepared from 14- and 21-days of age corresponding to rat puberty, and ABP mRNA was induced by dexamethasone. These results suggest that ABP gene is transcriptionally regulated by dexamethasone in primary Sertoli cell cultures.

Age Factors↗

PubMed1996

Alterations in CD4 dependence accompany T cell development and differentiation.

Several studies have indicated that the necessity for co-receptor engagement during T cell activation depends on the avidity of the TCR-MHC interaction under investigation. Using thymocytes, naive T cells and a long-term T cell line isolated from 2B4 TCR transgenic mice, we have examined the role of the CD4 co-receptor on cells expressing the identical TCR at multiple stages of T cell maturation. When anti-CD4 Fab fragments were used to block CD4-MHC class II interactions, we found decreasing CD4 dependence as T cells matured. As a second approach to examining the role of the CD4 co-receptor, we generated I-Ek mutants defective in CD4 interactions. In the course of this study, we identified a new potential site for CD4 interaction in the beta1 domain of I-Ek. The new beta1 mutation and a mutation in the previously described CD4 binding site in the beta2 domain both interfere with stimulation of 2B4 thymocytes, but not mature T cells. Together these data demonstrate that the role of the CD4 co-receptor depends on the state of maturation of the T cell.

Animals↗

PubMed1996

Soluble CD23 protein in the peritoneal fluid of patients with endometriosis.

Activated B cells are known to produce soluble CD23 protein (sCD23) from their membranes. We recently showed a higher concentration of sCD23 in the serum of patients with endometriosis. As the commonest site of endometriosis is the peritoneal cavity, we sought to evaluate the concentration of sCD23 in the peritoneal fluid of 47 fertile symptomatic women with endometriosis and 35 fertile women without endometriosis. Endometriosis was diagnosed by laparoscopy and confirmed by histopathology. There was a statistically significant difference between the sCD23 concentrations in the endometriosis and control groups (P < 0.05). When endometriosis was defined based on the revised American Fertility Society (AFS) Score, patients with mild (AFS 1 and II) but not severe (AFS III and IV) endometriosis showed a higher and significant difference in the concentration of sCD23 when compared with the controls (P < 0.05). There was no significant correlation between the peritoneal fluid concentration of sCD23 and the phase of the menstrual cycle. We conclude that the concentration of sCD23 is higher in the peritoneal fluid of patients with endometriosis when compared with the controls, suggestive of B cell activation in patients with endometriosis. Furthermore, mild endometriosis is immunologically more active than severe endometriosis as defined by the current classification.

Ascitic Fluid↗

PubMed1996

Effects of intermittent food restriction and refeeding on energy efficiency and body fat deposition in sedentary and exercised rats.

The effects of body weight cycling on energy metabolism and body fat accumulation were examined in sedentary and exercised rats. Ten rats were sacrificed before the experiment to obtain basal data, and then 90 rats were divided into three groups; control (CN), food restricted (FR) and weight cycling (WC). Food intake in rats of the FR group was restricted constantly to 70% of the intake of the CN group. The rats of WC group were subjected to four bouts of weight cycling consisting of 7-days food restriction followed by 7-days refeeding, but were fed the same total amount of dietary energy as that of the FR group throughout the experimental period. The rats of all groups were meal-fed twice a day. Half of the rats in each group were exercised by running on a treadmill (30 min/day) throughout the experimental period. The body weight, abdominal adipose tissue weight, body fat, body protein and energy restoration for the study in both sedentary and exercised groups were greater in the WC group than in the FR group. The resting metabolic rate of the WC group after four bouts of weight cycling was lower than that of the FR group in the sedentary rats, but this difference was not observed in the exercised rats. Also, the thermic effect of food (TEF) in the sedentary rats for 6 h after a meal was significantly less in the WC group as compared to that of the FR group. However, the TEF for the exercised rats was not different between the two groups. The serum insulin level, activities of lipogenic enzymes and lipoprotein lipase in adipose tissue for the sedentary rats of the WC group were higher than those of the FR group, but did not differ in the exercised rats. These results suggest that weight cycling increases body fat deposition and energy efficiency by decreasing energy expenditure, particularly the TEF, and that exercise training can alleviate the effects of weight cycling on the energy metabolism.

Adipose Tissue↗

PubMed1996

Role of the eosinophil in allergic reactions.

The eosinophil may have several functions in health and in the pathogenesis of allergic and other diseases. Some roles of the eosinophil are based on the acute, effector responses of this cell, its capacity to generate biologically active lipid mediators and release its granule contents, including its distinctive cationic proteins. Whilst the effector responses of eosinophils are important for their contribution to the acute pathogenesis of allergic diseases, a fuller understanding of the eosinophil requires evaluation of the role this cell may play at tissue sites, especially submucosal sites, where the cell is normally localized in the absence of disease. Moreover, for the long-lived, tissue-resident eosinophil, definition of the interactions that occur between the eosinophil and other immune cells is germane to understanding the functions of eosinophils both in acute and chronic diseases. Many allergic diseases are characterized by heightened accumulation of eosinophils and are chronic ongoing diseases.

Animals↗

PubMed1996

Children's understanding of the meaning and functions of verbal irony.

We investigated children's understanding of irony and sensitivity to irony's meanness and humor. In Study 1, 89 participants (5-6-year-olds, 8-9-year-olds, adults) heard ironic and literal criticisms, and literal compliments. Comprehension of irony emerged between 5 and 6 years of age. Ratings of humor increased with age; ratings of meanness did not (showing that all ages perceived irony as more muted than literal criticism). In Study 2, results from 135 participants (6-7-year-olds, 8-9-year-olds, and adults) replicated these findings and revealed the role of form and intonation. Thus, comprehension of irony emerges between 5 and 6 years of age, and sensitivity to the muting function develops prior to sensitivity to the humor function.

Age Factors↗

PubMed1995

Reduced level of octamer binding transcription factor (Oct-1) is correlated with H2B histone gene repression during differentiation of HL-60 cells by all-trans retinoic acid.

To gain insight on the role of transacting factors in the regulatory mechanism of H2B histone gene expression during the differentiation of HL-60 cells by all-trans retinoic acid (retinoic acid), the binding pattern of the nuclear proteins to various elements in the human H2B histone upstream region has been investigated with DNase I footprinting and DNA mobility shift assay. The level of H2B histone mRNA was markedly reduced at 48 hr in retinoic acid-treated HL-60 cells. The H2B histone mRNA was repressed in proportion to the concentration of retinoic acid. In DNase I footprinting analysis, a nuclear factor (octamer binding transcription factor, Oct-1) bound at -42 bp (ATTTGCAT) both before and after retinoic-acid-induced differentiation of HL-60 cells. One DNA-protein complex was formed by DNA mobility shift assay, and the level of Oct-1 decreased during retinoic-acid-induced differentiation. In the cycloheximide-treated HL-60 cells, the level of Oct-1 also reduced. These results suggest that the transcriptional repression of H2B histone gene during retinoic-acid-induced differentiation in HL-60 cells may be mediated by reduced level of Oct-1.

Base Sequence↗

PubMed1995

Molecular dynamics of the anti-fluorescein 4-4-20 antigen-binding fragment. 1. Computer simulations.

Two 174 ps molecular dynamics simulations of the solvated, 4-4-20 antigen-binding fragment (Fab) were performed: one with antigen (fluorescein) in the antigen-combining site and another with it removed. At the beginning of the second simulation, fluorescein was relocated from the antigen-combining site to a point outside the cutoff distance for nonbonded interactions by applying a "pulling force". Initially, the antigen-combining site collapsed when fluorescein was removed but gradually re-formed as the simulation progressed. In addition, several other differences were observed between the two simulations. These included (i) structural rearrangements of key contact residues in the antigen-combining site, (ii) significant differences in the degree of hydration of the antigen-combining site, (iii) a more acute elbow bend angle in the case of the unliganded form, and (iv) less correlated motions of amino acid residues in the unliganded form. These observations suggested that the Fab without fluorescein exhibited a greater degree of segmental flexibility than the Fab with fluorescein. Time-resolved fluorescence experiments were performed in order to validate this prediction, and the results are described in the following paper [Lim et al. (1995) Biochemistry 34, 6975-6984].

Antigens↗

PubMed1995

Molecular dynamics of the anti-fluorescein 4-4-20 antigen-binding fragment. 2. Time-resolved fluorescence spectroscopy.

Time-resolved fluorescence experiments were performed to investigate the dynamic aspects of the antigen-binding fragment (Fab) of a high-affinity monoclonal antibody (4-4-20) which binds the fluorescent hapten fluorescein. Both the unliganded Fab and a complex of the Fab with a nonfluorescent analog of fluorescein (fluoresceinamine, FLM) were examined. A fluorescence polarization probe [5-[[2-[(iodoacetyl)amino]ethyl]amino]naphthalene-1-sulfonic acid, AEDANS] was covalently attached to the C-terminus of the Fab. Experiments were performed at three different temperatures (10, 25, and 35 degrees C), and phase-modulation data sets were collected for five different molar ratios of FLM to Fab at each temperature. Global analyses were then used to extract values for fluorescence lifetime and rotational correlation time from these data. In the lifetime analysis the best fit was obtained when the emission of AEDANS was described by a Lorentzian distribution of lifetimes (tau = 15.6 ns, distribution width = 3.4 ns, both at 25 degrees C), which suggested that the probe experienced a heterogeneous environment. Anisotropy analyses suggested that two different rotational components were present. The first was attributed to the global motion of the Fab and exhibited a rotational correlation time (theta 1) of ca. 33 ns at 25 degrees C. This component was relatively unaffected by antigen binding. The second rotational component was attributed to the local or segmental motion within the Fab and exhibited a rotational correlation time (theta 2) of 1.1 ns at 25 degrees C. This value increased by more than 50% upon antigen binding, a result which was consistent with molecular dynamics simulations of the same Fab--fluorescein system [Lim & Herron (1995) Biochemistry 34, 6962-6974]. Furthermore, statistical analysis showed that this increase was significant at the 95% confidence level.

Amino Acid Sequence↗

PubMed1995

Follicle-stimulating hormone transiently induces expression of protooncogene c-myc in primary Sertoli cell cultures of early pubertal and prepubertal rat.

The protooncogene c-myc plays an important role in the regulation of cellular proliferation and differentiation. To evaluate the possibility that the protooncogene c-myc plays some roles in follicle-stimulating hormone (FSH)-dependent gene regulation of Sertoli cells, the effects of FSH on the expression of c-myc has been investigated in primary Sertoli cell cultures. FSH was no change to the c-myc mRNA level before 18 h, but transiently increased c-myc mRNA levels, with maximal stimulation reached in 18 h. The induction of c-myc was dependent on the concentration of FSH. Th c-myc mRNA was also increased after treatment with dibutyryl c-AMP and forskolin in primary Sertoli cell cultures. FSH-dependent c-myc mRNA levels were superinduced in cells treated for 3 h with cycloheximide but it was reduced by actinomycin-D pretreatment. Even in the absence of FSH in culture medium c-myc mRNA was clearly detectable in Sertoli cells from 8-day-old rats but hardly detectable in cells from 14 and 28 days of age. FSH stimulated c-myc mRNA expression in the primary Sertoli cells derived from only 8- and 14-day-old rats but had almost no effect in the 28-day-old rats. These results suggest that FSH induces c-myc mRNA levels in the primary Sertoli cells from prepubertal and early pubertal rats, and then transient expression of c-myc may be responsible for some roles in the regulation of FSH-dependent genes in Sertoli cells.

Animals↗