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Biomedical subjects

K F Lee

Publications and source records attributed to K F Lee.

At least 37 records · Page 2Linked to original sources
PubMed2002

The synthesis and fate of glycodelin in human ovary during folliculogenesis.

The ontogeny of glycodelin in human ovarian follicles during folliculogenesis was studied. Glycodelin immunoreactivity began to be detected in the granulosa cells and thecal cells of late secondary follicles. Immunoreactivity was also found in both the luteinized granulosa cells and cumulus cells obtained from women undergoing the assisted reproduction treatment. However, only the luteinized granulosa cells, and not the cumulus cells, expressed glycodelin mRNA. Results also showed that the cumulus cells took up radiolabelled glycodelin and partially deglycosylated some of it. Glycodelin (and a partially deglycolsylated form of glycoldelin) appeared to complex with two cytoplasmic or membrane components of the cumulus cells. The data also demonstrated that ZIF-1, a glycoprotein isolated from human follicular fluid, was immunologically similar to glycodelin. In conclusion, we suggest that glycodelin is synthesized in the granulosa cells of ovarian follicles at late secondary follicle stage. It then may be released into the follicular fluid from where it is taken up and partially modified by the cumulus cells.

Binding, Competitive↗
PubMed2002

Submandibular Castleman's disease.

Castleman's disease is a rare benign lymphoid tumour of unknown aetiology, which usually appears as a solitary mediastinal mass. We report an unusual case of Castleman's disease, an asymptomatic submandibular mass in the lower jaw, and we discuss the computed tomography appearance.

Castleman Disease↗
PubMed2001

A compendium of gene expression in normal human tissues.

This study creates a compendium of gene expression in normal human tissues suitable as a reference for defining basic organ systems biology. Using oligonucleotide microarrays, we analyze 59 samples representing 19 distinct tissue types. Of approximately 7,000 genes analyzed, 451 genes are expressed in all tissue types and designated as housekeeping genes. These genes display significant variation in expression levels among tissues and are sufficient for discerning tissue-specific expression signatures, indicative of fundamental differences in biochemical processes. In addition, subsets of tissue-selective genes are identified that define key biological processes characterizing each organ. This compendium highlights similarities and differences among organ systems and different individuals and also provides a publicly available resource (Human Gene Expression Index, the HuGE Index, http://www.hugeindex.org) for future studies of pathophysiology.

Cluster Analysis↗
PubMed2001

Distinct roles of nerve and muscle in postsynaptic differentiation of the neuromuscular synapse.

The development of chemical synapses is regulated by interactions between pre- and postsynaptic cells. At the vertebrate skeletal neuromuscular junction, the organization of an acetylcholine receptor (AChR)-rich postsynaptic apparatus has been well studied. Much evidence suggests that the nerve-derived protein agrin activates muscle-specific kinase (MuSK) to cluster AChRs through the synapse-specific cytoplasmic protein rapsyn. But how postsynaptic differentiation is initiated, or why most synapses are restricted to an 'end-plate band' in the middle of the muscle remains unknown. Here we have used genetic methods to address these issues. We report that the initial steps in postsynaptic differentiation and formation of an end-plate band require MuSK and rapsyn, but are not dependent on agrin or the presence of motor axons. In contrast, the subsequent stages of synaptic growth and maintenance require nerve-derived agrin, and a second nerve-derived signal that disperses ectopic postsynaptic apparatus.

Agrin↗
PubMed2001

Gas extravasation complicating laparoscopic extraperitoneal inguinal hernia repair.

Carbon dioxide can extravasate from the abdominal cavity during insufflation and result in pneumomediastinum, pneumothorax, and subcutaneous emphysema. We report a case of unilateral pneumothorax with pneumomediastinum and subcutaneous emphysema after laparoscopic extraperitoneal bilateral inguinal hernia repair. Additionally, we discuss the pathophysiology, diagnostic work-up, and management of this malady. Because of the natural resolution of CO2 pneumothoraces, observation for asymptomatic patients is appropriate, whereas tube thoracostomy should be reserved for symptomatic patients. It is utmost importance to determine the etiology of gas extravastion and consider other complications such as airway or esophageal injury or pulmonary barotrauma.

Abdomen↗
PubMed2001

Establishment and characterization of an immortalized human oviductal cell line.

Human oviductal cells stimulate embryo development in vitro partly by the production of embryotrophic glycoproteins. The identity of these glycoproteins is not yet known mainly because oviductal samples are limited and that the cultured parental oviductal cells cannot produce sufficient amount of embryotrophic factors for characterization. In this study, human oviductal epithelial cells (OE) were immortalized by HPV 16 E6/E7 open reading frame (ORF) by retroviral expression. The characteristics of this immortalized cell line (OE-E6/E7) were compared to the parental OE. HPV 16 E6/E7 DNA was found only in OE-E6/E7 but not in OE. Human oviduct-specific glycoprotein, estrogen receptors, and cytokeratin were found in both cell types. Both OE and OE-E6/E7 possessed telomerase activities but the former had much lower activity. OE-E6/E7 also produced glycoproteins with chromatographic behavior similar to the embryotrophic glycoproteins derived from OE. These results showed that OE-E6/E7 retained a number of characteristics of OE. The development of preimplantation mouse embryo was significantly better after coculture with OE-E6/E7 when compared to medium alone culture in term of blastulation rates (52% vs. 32%) and blastocyst diameter (113.0 +/- 2.07 microm vs. 83.9 +/- 5.23 microm). This immortalized cell line can be used as a continuous and stable in vitro system for the study of the oviductal embryotrophic activity. Mol. Reprod. Dev. 59: 400-409, 2001.

Animals↗
PubMed2001

Quantification of transforming growth factor beta1 (TGFbeta1) mRNA expression in mouse preimplantation embryos and determination of TGFbeta receptor (type I and type II) expression in mouse embryos and reproductive tract.

We hypothesized that transforming growth factor beta1 (TGFbeta(1)) and its receptors play a role in the interaction between the preimplantation embryo and the reproductive tract. To investigate this hypothesis, TGFbeta 1 mRNA in mouse embryos was quantified by competitive reverse transcription-polymerase chain reaction using an RNA mimic. TGFbeta 1 was first detected in the unfertilized oocyte, disappeared after fertilization and was expressed again at the 2-cell stage (4410 +/- 1330 transcripts/embryo). Its expression increased gradually, peaked at the 8-cell stage (58 600 +/- 17 300 transcripts/embryo) and declined rapidly after the morula stage reaching a concentration of 1520 +/- 546 transcripts/embryo at the blastocyst stage. The mRNA levels of TGFbeta 1 at the 8-cell and morula stages were significantly higher than that at other cell stages (P < 0.05). The expression of TGF receptors in embryos and in the reproductive tract was also investigated. Both TGFbeta(1) type I (ALK-5) and type II TGFbeta receptors were detected in embryos from 1-cell to blastocyst stage by immunohistochemistry. Northern hybridization and immunohistochemistry showed a constant expression of both TGFbeta receptors in the oviduct from day 1 to day 4 of pregnancy, whilst in the uterus there was a marked increase in the expression of TGFbeta type I receptor on day 3. Expression of TGFbeta type II receptor in the uterus remained unaltered throughout the study period. This study has shown that preimplantation mouse embryos produce TGFbeta(1) and that both the embryos and the reproductive tract are responsive to TGFbeta(1) in the preimplantation period.

Activin Receptors, Type I↗
PubMed2001

A comparative study of gene expression in murine embryos developed in vivo, cultured in vitro, and cocultured with human oviductal cells using messenger ribonucleic acid differential display.

The objectives of this study were to compare the mRNA expression patterns in early mouse embryos in different culture conditions by differential display reverse transcription-polymerase chain reaction (DDRT-PCR). Embryos developed in vivo, cultured in vitro, and cocultured with human oviductal epithelial cells were studied at the 2-cell, 4-cell, 8-cell/morula, and blastocyst stages. Messenger RNA profiles were displayed by DDRT-PCR using downstream T11VV (V = A, C, or G) and upstream decamer primers. Total cDNA banding patterns were highly conserved in the three groups studied. Some fragments are unique in different culture conditions. Thirteen out of the 40 selected differentially expressed clones were characterized. The DNA sequence analyses of these clones displayed high sequence homology with cDNA sequences in the mouse expressed sequence tag database. Using semiquantitative RT-PCR, we confirmed differential expression of these DD amplicons in the three groups of embryos. The temporal expression of some of the selected DD amplicons during preimplantation development were studied in the three groups of embryos. In conclusion, DDRT-PCR is an effective tool for contrasting gene expression patterns and characterizing mRNA transcripts in mouse embryo.

Animals↗
PubMed2001

Mice that lack corticotropin-releasing factor (CRF) receptors type 1 show a blunted ACTH response to acute alcohol despite up-regulated constitutive hypothalamic CRF gene expression.

BACKGROUND: The purpose of this work was to determine the influence of acute alcohol treatment, injected intraperitoneally, on the hypothalamic-pituitary-adrenal axis of mice that lack type 1 receptor for corticotropin-releasing factor (CRFR1). METHODS: CRFR1-deficient (CRFR1-/-), heterozygous (CRFR1+/-), and wild-type (CRFR1+/+) mice were generated and maintained under standard conditions. Homozygous, heterozygous, and wild-type offspring were identified by polymerase chain reaction analysis of tail DNA. Experiments were performed on 9- to 16-week-old male and female mice. All blood samples were obtained by rapid decapitation of conscious mice conducted between 10 AM-12 PM. Blood sample collection was completed within 20 to 30 sec of disturbing the animals, and all samples were terminal. Preliminary experiments were conducted to determine the time-course of the ACTH and hypothalamic responses to alcohol in all three groups of mice, and a single time point (30 min and 2 hr, respectively), corresponding to peak responses, was chosen to measure the corresponding parameters in all subsequent studies. RESULTS: In vehicle-injected animals, basal ACTH and corticosterone levels were statistically comparable in heterozygotes and mice with a null allele for the CRFR1 gene, although values of this latter hormone were slightly lower in the mutants. Alcohol (4.0 g/kg) elicited the expected significant (p < 0.01) increase in plasma ACTH and corticosterone levels in heterozygous mice. These responses were virtually abolished or markedly decreased, respectively, in CRFR1-deficient animals. As previously reported, constitutive CRF mRNA levels were elevated in the paraventricular nucleus (PVN) of the hypothalamus in mice that lacked CRFR1, compared to wild-type control mice. Interestingly, this was not the case for transcripts of the immediate early gene NGFI-B. When measured 2 hr after alcohol, PVN NGFI-B gene expression was significantly (p < 0.01) increased in both control and mutant mice, as were CRF mRNA levels in mutant mice, but the hypothalamic responses of the mutants were larger (p < 0.01) than those of the control mice. This difference may be due, at least in part, to the lack of steroid feedback in the mutants. CONCLUSION: These results indicate that although the intraperitoneal injection of alcohol remains capable of eliciting PVN CRF neuronal activation in mice that lack CRFR1, the ACTH and corticosterone responses are significantly blunted, a phenomenon believed to be due to the lack of CRFR1 in the pituitary of these animals.

Adrenocorticotropic Hormone↗
PubMed2001

Emergency laparoscopic orchidectomy for torsion of intra-abdominal testis: a case report.

Torsion of an intraabdominal testis is a rare cause of acute abdominal pain. With a history of undescended testis, it is difficult to establish the diagnosis and to exclude other emergency abdominal conditions without a laparotomy. The following case report illustrates the usefulness of laparoscopy as a diagnostic as well as a therapeutic tool in such a condition.

Adult↗
PubMed2001

Myxoma of the gingiva: a case report and literature review.

Soft tissue myxomas of the oral and para-oral tissue are extremely rare. Only two cases of myxoma of gingiva have been reported in the literature. The histogenesis of these lesions remains obscure. We report a case of gingival myxoma in a 37-year-old man. A firm ovoid soft tissue mass measuring 1.5 x 1.2 x 1 cm in size was noted at the mesio-lingual gingiva of a partially impacted right mandibular third molar. Radiographic examination revealed an impacted mandibular third molar with normal radiographic bony consistency of the mandible. Excisional biopsy was performed with no evidence of recurrence after 8 months. Histological examination showed stromal mass composed of myxoid-like fluid in fibrovascular stroma and scanty inflammatory cell infiltration, suggesting myxomas of the oral soft tissues and jaws. Immunohistochemical stains with S-100 protein, desmin and smooth muscle specific actin yielded negative results, and those with alcian blue, periodic-acid-Schiff, mucicarmine, vimentin and reticulin were positive. Tumor cells of mesenchymal origin without neurogenic or muscular derivations and myxoid matrix composed of acid mucopolysaccharides in this lesion further confirmed the diagnosis of myxoma. Periodontal ligament origin cannot be completely excluded due to tumor location and its association with an impacted molar. However, further study is necessary to clarify the origin and histogenesis of these lesions.

Adult↗
PubMed2000

Molecular cloning and expression analysis of human glycogen synthase kinase-3 alpha promoter.

Human glycogen synthase kinase-3 alpha (GSK-3 alpha) is a serine/threonine kinase that phosphorylates a variety of cytoplasmic and nuclear proteins. It also phosphorylates components of the neuronal cytoskeleton including tau and neurofilament heavy chain. Hyperphosphorylated tau is found in neurofibrillary tangles, a hallmark of Alzheimer's disease and aberrant phosphorylation of neurofilament heavy chain is observed in motor neuron disease. Alterations in GSK-3 alpha activity may therefore contribute to the disease process in these disorders. As a first step to understand the transcriptional regulation of GSK-3 alpha, a 2-kb (p-1751/+243) DNA fragment upstream of the GSK-3 alpha initiation codon was obtained from a YAC clone and characterised. Using primer extension assays, a putative transcriptional start site was located to a G nucleotide 244 bp upstream of the ATG codon. Several transcription factor-binding sites were identified on the promoter region, but no TATA-like element was located close to the start site. Deletion mutants of the 2-kb DNA fragment were generated and fused to a promoterless chloramphenicol acetyltransferase (CAT) gene. Transfection study in a neuroblastoma cell line revealed the 1-kb (p-719/+243) fragment carried strong promoter activity, while the 2-kb construct that contains an Alu-like sequence was only 50% active.

Alu Elements↗
PubMed2000

Suppression subtractive hybridization identifies genes expressed in oviduct during mouse preimplantation period.

Fertilization and development of mouse embryos occur in the ampullae of oviduct. Various growth factors and embryotrophic factors produced by the oviductal cells have been demonstrated to enhance embryo development in vitro. As a step towards understanding the genetic changes of mouse oviduct during mouse embryos preimplantation period, we adopted suppression subtractive hybridization (SSH) to establish four subtracted cDNA libraries to identify (1) oviduct-expressing genes, and (2) genes that may support embryo development in vivo. Using this method, we isolated 82, 88, 99, and 109 clones from four mouse libraries prepared from 0 (day 0), 24 (day 1), 48 (day 2), and 72 h (day 3) post-human chorionic gonadotropin (hCG) treated mice. Reverse dot-blot analysis confirmed that 25 (day 0), 24 (day 1), 40 (day 2), and 29 (day 3) clones were highly expressed in mouse oviduct when compared to other tissues. DNA sequence analysis identified genes encoding mouse oviduct-specific glycoprotein (MOGP), actin-binding protein 280, and several viral genes. Northern analysis confirmed that the genes were mainly expressed in oviduct, with some viral genes also expressed in uterus. About 9% of these oviduct expressing clones (11/118) were novel. We further demonstrated that one of the novel clones ODEG0-17 was expressed in the oviduct during early embryo preimplantation period and rarely in other tissues by RT-PCR. Our results show that SSH is a powerful method applicable to identifying tissue-specific transcripts on fertilization and development.

Animals↗
PubMed2000

p75 is important for axon growth and schwann cell migration during development.

Mice lacking the low-affinity neurotrophin receptor p75 have multiple peripheral neural deficits. Here we examined the developmental nature of these deficiencies. Peripheral axons in p75 -/- embryos were severely stunted and poorly arborized from embryonic day 11.5 (E11.5) to E14.5. In vitro, neurite outgrowth from the dorsal root ganglia was significantly decreased in the p75 -/- embryos at E12.5, suggesting that stunted axonal growth in the embryo may result in part from defects in neurite elongation. Additionally, Schwann cell marker S100beta immunoreactivity was decreased or absent along the growing axons of the ophthalmic branch from the trigeminal ganglia in p75 -/- embryos. Electron microscopy studies of the axons of the trigeminal ganglion at E13.5 revealed that in the p75 mutant embryo, nerve bundles were highly impaired and that coverage of the growing axons by Schwann cell cytoplasm was substantially reduced. In vitro, Schwann cell migration from the dorsal root ganglia was significantly decreased in the p75 -/- embryos at E12.5, suggesting that the lack of S100beta staining and Schwann cell coverage in the p75 mutant results from a deficit in Schwann cell migration. These results provide evidence that p75 is important in the developing embryo for regulating axon growth and arborization and for Schwann cell migration.

Animals↗
PubMed2000

Induction of postnatal schwann cell death by the low-affinity neurotrophin receptor in vitro and after axotomy.

Schwann cells express the low-affinity neurotrophin receptor (p75), but no role for either the neurotrophins or their cognate receptors in Schwann cell development has been established. We have found that Schwann cells isolated from postnatal day 1 (P1) or P2 mice that were p75-deficient exhibited potentiated survival compared to wild-type cells after growth factor and serum withdrawal. There was, however, no disparity in the survival of p75-deficient and wild-type Schwann cells isolated at embryonic day 15, suggesting that the death-inducing effects of p75 are developmentally regulated. A comparable degree of cell death was also observed in the sciatic nerves of both wild-type and p75-deficient mice at P1. However, 24 hr after axotomy, there was a 13-fold increase in the percentage of apoptotic nuclei in the distal nerve stumps of the transected sciatic nerves of neonatal wild-type but not p75-deficient mice. The expression of both the p75 and nerve growth factor (NGF) genes was upregulated after axotomy in neonatal wild-type nerves. Collectively, these results suggest that NGF-mediated activation of p75 is likely to be an important mediator of Schwann cell apoptosis in the context of peripheral nerve injury.

Age Factors↗