Biomedical subjects

J H Lim

Publications and source records attributed to J H Lim.

At least 55 records · Page 3Linked to original sources

PubMed2000

Cloning and expression of a novel zinc finger gene, Fez, transcribed in the forebrain of Xenopus and mouse embryos.

We have identified and cloned a novel zinc finger gene, Fez (forebrain embryonic zinc-finger), as a potential downstream determinant of anterior neural plate formation in Xenopus. Fez was isolated as one of several neural-specific genes that was induced by the neuralizing factor, noggin (Smith and Harland, 1992. Cell 70, 829-840), in uncommitted ectoderm. Fez has an open reading frame comprising 466 amino acids, and contains six C(2)H(2) type zinc finger domains, which are highly conserved among Drosophila, zebrafish, mouse, and human. In Xenopus, the expression of Fez begins at stage 12 in the rostral end of the neural plate, and by stage 45, it is localized to several telencephalic regions, including the olfactory bulbs, nervus terminalis, and ventricular zone. The mouse homologue of Fez is similarly expressed in the mouse forebrain by embryonic day 11.

Amino Acid Sequence↗

PubMed2000

The distribution and requirements of microtubules and microfilaments in bovine oocytes during in vitro maturation.

Microtubules and microfilaments are major cytoskeletal components and important modulators for chromosomal movement and cellular division in mammalian oocytes. In this study we observed microtubule and microfilament organisation in bovine oocytes by laser scanning confocal microscopy, and determined requirements of their assembly during in vitro maturation. After germinal vesicle breakdown, small microtubular asters were observed near the condensed chromatin. The asters appeared to elongate and encompass condensed chromatin particles. At the metaphase stage, microtubules were observed in the second meiotic spindle at the metaphase stage. The meiotic spindle was a symmetrical, barrel-shaped structure containing anastral broad poles, located peripherally and radially oriented. Treatment with nocodazole did not inhibit germinal vesicle breakdown. However, progression to metaphase failed to occur in oocytes treated with nocodazole. In contrast, microfilaments were observed as a relatively thick uniform area around the cell cortex and overlying chromatin following germinal vesicle breakdown. Treatment with cytochalasin B inhibited microfilament polymerisation but did not prevent either germinal vesicle breakdown or metaphase formation. However, movement of chromatin to the proper position was inhibited in oocytes treated with cytochalasin B. These results suggest that both microtubules and microfilaments are closely associated with reconstruction and proper positioning of chromatin during meiotic maturation in bovine oocytes.

Actin Cytoskeleton↗

PubMed2000

Dysregulated production of interferon-gamma, interleukin-4 and interleukin-6 in early tuberculosis patients in response to antigen 85B of Mycobacterium tuberculosis.

Both interferon-gamma (IFN-gamma) and interleukin (IL)-4 expression in T cells and IL-6 expression in cells of the monocyte/macrophage lineage were monitored using antigen 85B (Ag85B) protein and purified protein derivative (PPD) antigen in the early stages of tuberculosis (TB). We showed that the levels of cell-associated IFN-gamma and IL-4 (mRNA and intracellular cytokine) in Ag85B-stimulated T cells were significantly depressed in TB patients compared with those in healthy tuberculin reactors. On the other hand, the capacity of peripheral blood mononuclear cells (PBMC) to produce IL-6 spontaneously ex vivo was enhanced in patients (P < 0. 001), but their corresponding capacities to respond to Ag85B were not significantly different from those of normal donors. After 2 months of antituberculosis therapy, the mean blastogenic responses of Ag85B-stimulated PBMC from seven TB patients were increased 6. 1-fold (P = 0.011). Furthermore, the proportions of both IFN-gamma- (P < 0.01) and IL-4- (P = 0.05) producing T cells were significantly increased. However, those of IL-6-producing cells were diminished in response to Ag85B (P = 0.05). Our results suggest that there may be an altered regulation of IFN-gamma, IL-4 and IL-6 to Ag85B in the early stages of TB.

Acyltransferases↗

PubMed2000

Choledochal cyst: comparison of MR and conventional cholangiography.

AIMS: To assess the diagnostic value of magnetic resonance (MR) cholangiography versus conventional cholangiography in patients with choledochal cyst and to determine whether MR cholangiography can be considered an alternative to conventional cholangiography. MATERIALS AND METHODS: Thirteen patients with choledochal cyst were examined by MR cholangiography and conventional cholangiograms. Magnetic resonance cholangiography employed T2-weighted axial and coronal fast spin-echo, single and multislab single-shot fast spin-echo sequences, including source images with maximum intensity projections. The diagnostic value of MR cholangiography and conventional cholangiograms was assessed and compared using the criteria of depiction of morphology, anomalous pancreaticobiliary duct union and demonstration of complications such as stones. A four-point diagnostic scale was applied to the delineation of the ductal anatomy with the Wilcoxon signed-ranks test and McNemar's test used for statistical analysis. RESULTS: The depiction of the choledochal cyst was significantly better with MR cholangiography than with conventional cholangiography (P = 0.03). The detection rate of an anomalous pancreaticobiliary duct union was not significantly different with either method (P = 0.641), nor was the detection rate of bile duct stones (P = 0.375). CONCLUSION: Magnetic resonance cholangiography provides data equivalent to or superior to those from conventional cholangiography in evaluating choledochal cyst. Magnetic resonance cholangiography is recommended as a non-invasive examination of choice for the evaluation of choledochal cyst.

Adult↗

PubMed2000

Ultra-rapid freezing of human multipronuclear zygotes using electron microscope grids.

Developmental capacity of human multipronuclear (PN) zygotes cryopreserved using an ultra-rapid freezing method and electron microscope (EM) grids was studied. Multipronuclear zygotes obtained from a human IVF programme were used as an alternative to normal 2PN zygotes; they were divided into 3PN or >or =4PN zygotes and their in-vitro development and cryo-injury were compared according to PN number. EFS30, which consisted of 30% ethylene glycol, 18% Ficoll, 0. 5 mol/l sucrose and 10% fetal bovine serum with added modified Dulbecco's phosphate buffered saline was used as the freezing solution. After ultra-rapid freezing and thawing 85.5% of multipronuclear zygotes survived. A comparison of cleavage rates between the control and cryopreserved groups showed no significant difference (3PN; 81.3 and 85.4% and > or =4PN; 90.0 and 95.7% respectively). Comparing the in-vitro development after thawing up to blastocyst formation on day 5 after IVF, the outcome of the frozen 3PN group (22.0%) was not different from that of control 3PN group (38.5%), while the outcome of the frozen > or =4PN group (4.5%) was significantly lower than that of control > or =4PN group (44.4%) (P < 0.05).

Cell Nucleus↗

PubMed2000

Depressed interleukin-12 (IL-12), but not IL-18, production in response to a 30- or 32-kilodalton mycobacterial antigen in patients with active pulmonary tuberculosis.

The secreted 30-kDa antigen (Ag) of Mycobacterium tuberculosis directly stimulates Th1-type protective cytokine responses in healthy tuberculin reactors but not in patients with active tuberculosis (TB). To examine the cytokine profiles attributable to Th1 suppression associated with active TB, interleukin-12 (IL-12), IL-18, and IL-10 production in response to a 30- or 32-kDa Ag in 16 patients with active pulmonary TB and 24 healthy controls was investigated by enzyme-linked immunosorbent assay. In TB patients, production of IL-12 p40, as well as gamma interferon (IFN-gamma), by 30- or 32-kDa Ag-stimulated peripheral blood mononuclear cells (PBMC) was significantly decreased compared with that in healthy tuberculin reactors. There were no significant differences in IL-18 production between patients and controls early during stimulation (16 h). However, PBMC from patients showed significantly enhanced IL-18 proteins after 96 h of stimulation. Similarly, higher IL-10 production was observed in the TB patients than in healthy tuberculin reactors. After 2 months of anti-TB therapy, the mean IFN-gamma and IL-12 p40 production and the mean blastogenic responses were significantly increased in PBMC in the 10 TB patients who were followed up. Our findings provide evidence that depressed IL-12 in response to the 30- or 32-kDa Ag is involved in the immunopathogenesis of human active pulmonary TB.

Acyltransferases↗

PubMed2000

Dysplastic nodules in liver cirrhosis: evaluation of hemodynamics with CT during arterial portography and CT hepatic arteriography.

PURPOSE: To evaluate the portal and arterial blood supplies to dysplastic nodules in the cirrhotic liver with computed tomography (CT) during arterial portography (CTAP) and CT hepatic arteriography (CTHA). MATERIALS AND METHODS: Nineteen histopathologically proved low-grade dysplastic nodules and 13 high-grade dysplastic nodules in 17 patients with liver cirrhosis were evaluated with CTAP and CTHA for the presence of portal and arterial blood supplies to the nodules. The nodules ranged from 0.4 to 4.5 cm in diameter (mean, 1.6 cm). RESULTS: The portal supply was present in 14 of the 19 (74%) low-grade dysplastic nodules and in seven of the 13 (54%) high-grade dysplastic nodules. The hepatic arterial supply was increased in four of the 19 (21%) low-grade dysplastic nodules, present in nine (47%), and absent in six (32%). The arterial supply was increased in four of the 13 (31%) high-grade dysplastic nodules, present in four (31%), and absent in five (38%). CONCLUSION: The portal and arterial supplies to the low- and high-grade dysplastic nodules were variable and inconsistent. Therefore, it is difficult to detect and characterize the dysplastic nodules on the radiologic images on the basis of the blood supply.

Adult↗

PubMed2000

Hepatocellular carcinoma: are combined CT during arterial portography and CT hepatic arteriography in addition to triple-phase helical CT all necessary for preoperative evaluation?

PURPOSE: To determine whether the combination of CT during arterial portography (CTAP) and CT hepatic arteriography (CTHA) provides an added benefit to triple-phase helical CT (THCT) alone in the preoperative evaluation of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Fifty-two consecutive patients with pathologically proved HCC underwent THCT (hepatic arterial, portal venous, and delayed phases) and combined CTAP and CTHA. Two radiologists reviewed the images in three sessions: first the THCT images alone, then with the CTAP images, and finally all three sets of images. RESULTS: There were 73 pathologically confirmed HCCs. Among 72 lesions considered as HCC at THCT, 69 were proved to be HCCs. Of the additional 37 nodules interpreted as HCC at CTAP, only one was confirmed as such. Among the additional 20 lesions presumed to be HCC at combined CTAP and CTHA, only two were proved to be HCCs. The sensitivity was 94% (69 of 73 lesions) at THCT, 96% (70 of 73) with additional CTAP, and 97% (71 of 73) with all three modalities. The positive predictive value was 96% (69 of 72) at THCT, 65% (70 of 107) with additional CTAP, and 80% (71 of 89) with all three modalities. CONCLUSION: The use of CTAP and CTHA, in addition to being invasive and costly, resulted in an unacceptably high false-positive rate without a substantial increase in sensitivity. Therefore, CTAP and CTHA are not recommended for preoperative evaluation of HCC; THCT alone is preferred.

Adult↗

PubMed2000

Detection of hepatocellular carcinomas and dysplastic nodules in cirrhotic livers: accuracy of helical CT in transplant patients.

OBJECTIVE: The purpose of this study was to evaluate the diagnostic efficacy of three-phase helical dynamic CT in the detection and characterization of hepatocellular carcinomas and dysplastic nodules in cirrhotic livers. SUBJECTS AND METHODS: Three-phase helical dynamic CT in 41 patients with liver cirrhosis was evaluated prospectively before orthotopic liver transplantation. The numbers of hepatocellular carcinomas and dysplastic nodules were assessed in the explanted livers and compared with pretransplantation CT findings. RESULTS: Examination of the explanted livers revealed 21 hepatocellular carcinomas in 15 patients and 23 dysplastic nodules in 10 patients. The size of the hepatocellular carcinomas was 0.6-5. 0 cm (mean, 1.9 cm), and that of the dysplastic nodules was 0.7-2.0 cm (mean, 1.0 cm). The use of helical dynamic CT enabled detection of 15 of 21 hepatocellular carcinomas (sensitivity, 71%) and nine of 23 dysplastic nodules (sensitivity, 39%). Patient sensitivity and specificity in the detection of hepatocellular carcinomas were 80% (12/15) and 96% (25/26), respectively, and for dysplastic nodules, 50% (5/10) and 97% (30/31), respectively. CONCLUSION: Three-phase helical dynamic CT is relatively insensitive for detection of hepatocellular carcinomas and dysplastic nodules in cirrhotic livers, especially for dysplastic nodules and hepatocellular carcinomas smaller than 2 cm.

Carcinoma, Hepatocellular↗

PubMed2000

Malignant papillary neoplasms of the intrahepatic bile ducts: CT and histopathologic features.

OBJECTIVE. We describe the CT and pathologic features of malignant papillary neoplasms of the intrahepatic bile ducts in 15 patients. CONCLUSION. CT is a useful technique for revealing intraductal lesions, although the findings are nonspecific and variable. When intraductal masses or nodules are seen with localized dilatation of the intrahepatic bile ducts on CT scans, malignant papillary neoplasms of the intrahepatic bile ducts should be included in the differential diagnosis.

Adult↗

PubMed2000

Ultrasound examination of gastrointestinal tract diseases.

With recent technical advances, increasing use of sonography in the initial evaluation of patients with abdominal disease may allow the detection of unexpected tumor within the abdominal cavity. Easiness of sonographic detection of bowel pathology, purposely or unexpectedly, warrants the inclusion of bowel loops during ultrasound examination when a patient complains of symptoms indicating diseases of the bowel. In patients complaining of acute abdominal symptoms or nonspecific gastrointestinal symptoms and showing signs such as abdominal pain, diarrhea, hematochezia, change of bowel habit, or bowel obstruction, sonography may reveal the primary causes and may play a definitive role in making a diagnosis. On ultrasonography, abnormal lesions may appear as fungating mass with eccentrically located bowel lumen (pseudokidney sign) or symmetrical or asymmetrical, encircling thickening of the colonic wall (target sign). In patients with mass or wall thickening detected on ultrasonography, additional work-up such as barium study, CT or endoscopy would be occasionally necessary for making a specific diagnosis.

Abdomen, Acute↗

PubMed1999

Inhibitory patterning of the anterior neural plate in Xenopus by homeodomain factors Dlx3 and Msx1.

Patterning of the embryonic ectoderm is dependent upon the action of negative (antineural) and positive (neurogenic) transcriptional regulators. Msx1 and Dlx3 are two antineural genes for which the anterior epidermal-neural boundaries of expression differ, probably due to differential sensitivity to BMP signaling in the ectoderm. In the extreme anterior neural plate, Dlx3 is strongly expressed while Msx1 is silent. While both of these factors prevent the activation of genes specific to the nascent central nervous system, Msx1 inhibits anterior markers, including Otx2 and cement gland-specific genes. Dlx3 has little, if any, effect on these anterior neural plate genes, instead providing a permissive environment for their expression while repressing more panneural markers, including prepattern genes belonging to the Zic family and BF-1. These properties define a molecular mechanism for translating the organizer-dependent morphogenic gradient of BMP activity into spatially restricted gene expression in the prospective anterior neural plate.

Animals↗

PubMed1999

Characterization of two new channel protein genes in Arabidopsis.

Aquaporins, small channel proteins, found in a variety of organisms are members of the major intrinsic protein (MIP) superfamily and have been shown to facilitate water transport when expressed in Xenopus oocytes. We isolated two Arabidopsis cDNAs, SIMIP and SITIP, that encode protein homologues of the MIP superfamily. SIMIP exhibits a high degree of sequence homology to PIP3 and MIP1, and thus may belong to the plasmamembrane intrinsic protein (PIP) subfamily, whereas salt-stress inducible tonoplast intrinsic protein (SITIP) is highly homologous to VM23 and gamma-TIP, and therefore may belong to the TIP subfamily. Expression studies revealed that the two genes showed a different expression pattern. The SIMIP gene was expressed in a tissue-specific manner, for example, its highest transcript level is found in flowers, relatively low levels in siliques, and very low level in leaves and roots. In contrast, SITIP was expressed in nearly equal amounts in all the tissues we examined. Also, the expression of SIMIP and SITIP showed a temporal regulation pattern. For example, the highest expression level was at 1 week after germination. In addition, the transcript levels of SIMIP and SMTIP were increased upon NaCl and ABA treatments. The biological function of the 2 genes were investigated using two NaCl stress-sensitive yeast mutant strains. The mutant yeast cells expressing these 2 genes were more resistant to high NaCl conditions. The results suggest that the proteins encoded by these genes may be involved in the osmoregulation in plants under high osmotic stress such as under a high salt condition.

Abscisic Acid↗

PubMed1999

Fas ligand and Fas are expressed constitutively in human astrocytes and the expression increases with IL-1, IL-6, TNF-alpha, or IFN-gamma.

Fas ligand (FasL) and Fas are mediators of apoptosis, which are implicated in the peripheral deletion of autoimmune cells, activation-induced T cell death, and cytotoxicity mediated by CD8+ T cells. Fas is also believed to be involved in several central nervous system diseases, but until now, the effector cells expressing FasL in the brain have not been identified. We investigated the expression levels of Fas and FasL with the stimulation of cytokines and the possible effector cells targeting Fas-bearing cells. Our data demonstrated that: 1) FasL is expressed constitutively on astrocytes taken from a fetus or an adult and that its expression increases when these cells are treated with IL-1, IL-6, or TNF-alpha in which the pretreatment of IFN-gamma triggers astrocytes to express more FasL; 2) astrocytes induce apoptosis in MOLT-4 cells through FasL; 3) Fas is also expressed constitutively and is up-regulated by IL-1, IL-6, or TNF-alpha in which the pretreatment of IFN-gamma triggers astrocytes to express more Fas; 4) apoptosis occurs when fetal astrocytes are treated with agonistic anti-Fas IgM Ab after culture with IFN-gamma and TNF-alpha; and 5) TNF-related apoptosis inducing ligand is up-regulated in fetal astrocytes with stimuli of IL-1 or TNF-alpha. These findings suggest a possible role of astrocytes in the induction of apoptosis in central nervous system diseases.

Adult↗

PubMed1999

Calcium-binding proteins: differential expression in the rat olfactory cortex after neonatal olfactory bulbectomy.

Calbindin, parvalbumin, and calretinin, members of EF-hand calcium-binding proteins, play important roles in buffering intracellular calcium ions. These proteins are localized in distinct populations of cells in the olfactory bulb (the primary sensory relay in the olfactory system) and its major synaptic target, the primary olfactory cortex (POC). In the present study, the postnatal expression of these calcium-binding proteins in layer III of POC was quantitatively examined 30 days after neonatal bulbectomy, a manipulation known to cause cell death and neurotransmitter changes. The numbers of both calbindin and parvalbumin-immunoreactive profiles showed significant increases (68% and 163%, respectively), while calretinin-immunoreactive profiles exhibited a 46% reduction. The data demonstrate that the expression of these calcium-binding proteins is regulated in part by the afferent input from the olfactory bulb. Furthermore, the resultant increase in calbindin and parvalbumin expression may provide neuroprotective support necessitated by possible alterations in intracellular calcium ions and other neurochemical factors that accompany neonatal bulb removal.

Animals↗

PubMed1999

Activity-dependent regulation of interleukin-1 beta immunoreactivity in the developing rat olfactory bulb.

Interleukin-1beta is a relatively small and abundant polypeptide that plays diverse roles in the central nervous system. In the present study, patterns of interleukin-1beta expression were observed in the olfactory bulbs of rats that had either undergone unilateral closure of the external naris or sham surgery on postnatal day 1 and then survived until postnatal day 30. Interleukin-1beta-immunoreactive fibers occupied distinct layers of the olfactory bulb. Dense immunostaining was found in the periglomerular and granule cell layers. Odor deprivation resulted in a noticeable reduction in interleukin-1beta immunoreactivity only in the periglomerular layer. The data demonstrate that interleukin-1beta is present abundantly in the bulbs, and that it can be regulated in an activity-dependent manner.

Animals↗

PubMed1999

The POU domain gene, XlPOU 2 is an essential downstream determinant of neural induction.

The POU domain gene, XlPOU 2, acts as a transcriptional activator during mid-gastrulation in Xenopus. Overexpression or misexpression of VP16-POU-GR, a fusion protein consisting of the strong activator domain of VP16 and the POU domain of XlPOU 2, results in ectopic expression of the neural-specific genes, nrp-1, en-2, and beta-tubulin. In contrast, overexpressing a dominant-inhibitory form of XlPOU 2 inhibits the chordin-induced neuralization of uncommitted ectoderm, and results in a loss of nrp-1 and en-2 expression in embryos. Furthermore, in uncommitted ectoderm, XlPOU 2 regulates the developmental neural program that includes a number of pre-pattern genes and at least one proneural gene, X-ngnr-1, thus playing a key role during neural determination.

Animals↗

PubMed1999

A 45-kDa cAMP-dependent phosphoprotein which is related to the product of Mst57Dc in Drosophila melanogaster.

In Drosophila, the catalytic subunit of cAMP-dependent protein kinase (PKA) is preferentially expressed in the brain and the male reproductive organs. Although the cAMP response element binding protein (CREB) is a major target of PKA in the brain, the target of PKA in the male reproductive organs has been unknown. In the present study, three cAMP-dependent phosphoproteins (referred to as pp45, pp20, and pp10) were detected in the lumen fluid of male accessory glands. They were tissue-specific secretory proteins that accumulated only after eclosion, and were transferred to females during mating as other secretory proteins of the accessory glands. Among them, the 45-kDa phosphoprotein was partially purified and characterized. The purified protein was phosphorylated in vitro by the catalytic subunit of PKA. The partial amino acid sequence of this 45-kDa phosphoprotein was identical to the predicted amino acid sequence of the Mst57Dc cDNA, which is a male accessory gland transcript.

Amino Acid Sequence↗