Biomedical subjects

S Lee

Publications and source records attributed to S Lee.

At least 415 records · Page 23Linked to original sources

PubMed2000

High-level, stable expression of blood group antigens in a heterologous system.

The detection and identification of blood group antibodies in patients is crucial for successful allogeneic blood transfusions. Current methods are highly subjective and rely on red blood cells (RBCs), which simultaneously express many blood group antigens, have a short shelf-life, and carry potential biohazard risks. To overcome these problems, we have used the approach of expressing individual blood group antigen-bearing proteins in a heterologous system. We report here the high-level surface expression of type I (Knops), type II (Kell), and type III/multi-pass (Duffy) membrane proteins that carry blood group antigens in mouse erythroleukaemic (MEL) cells using a vector containing the beta-globin locus control region. Importantly, the antigens expressed were detected specifically by a panel of patients' sera containing alloantibodies at sensitivities that are comparable to antigen-positive RBCs. Furthermore, in contrast to other mammalian expression systems, antigen expression was stable following freezing and thawing of the cell lines. Thus, this system has the potential both to replace the current use of RBCs by providing a one step method to detect and identify blood group antibodies and to allow the automation of antibody identification for the clinical laboratory.

Animals↗

PubMed2000

Disordered eating in three communities of China: a comparative study of female high school students in hong kong, Shenzhen, and rural hunan.

OBJECTIVE: To examine disordered eating and its psychological correlates among female high school students in three Chinese communities that lay on a gradient of socioeconomic development in China. METHOD: 796 Chinese students from Hong Kong, Shenzhen, and rural Hunan completed a demographic and weight data sheet, the Eating Attitudes Test (EAT-26), a Body Dissatisfaction Scale (BDS), the Beck Depression Inventory (BDI), and the Rosenberg Self-Esteem Scale (RSES). RESULTS: Compared to students in Hunan and to a lesser extent students in Shenzhen, students from Hong Kong were slimmer, but desired a lower body mass index (BMI), reported more body dissatisfaction, exhibited a more typical EAT-26 factor structure, scored higher on the "fat concern and dieting" factor, and constituted more EAT-26 high scorers. Multiple regression analyses indicated that BDS was the most significant predictor of fat concern at each site, but this effect was strongest in Hong Kong. Hunan students had significantly higher BDI scores but lower fat concern than Shenzhen and Hong Kong students. DISCUSSION: The consistent gradient of fat concern across the three communities gives credence to the view that societal modernization fosters disordered eating in women, possibly via the gendered social constraints that accompany it. It is also expressive of the marked socioeconomic heterogeneity within China nowadays. The predictable rising rate of eating disorders that follows global change will pose a growing public health challenge to Asian countries.

Adolescent↗

PubMed2000

The single neurofilament subunit of the lamprey forms filaments and regulates axonal caliber and neuronal size in vivo.

Neurofilaments (NFs) are composed of a heteropolymer of three related subunits in mammalian neurons, where they are a major component of the cytoskeleton in large neurons and are thought to regulate axonal diameter. NFs in the lamprey, while ultrastructurally and functionally indistinguishable from mammalian NFs, are polymers of a single subunit protein, NF180. In this study, we use the simplicity of lamprey NFs and the accessibility of the lamprey central nervous system (CNS) to examine the effects of overproducing NFs in an identified giant neuron in vivo, and thus to elucidate the role of NFs in regulating neuronal size and axonal caliber in the vertebrate CNS. We show that overexpression of NF180 tagged with a variant of Green Fluorescent Protein (EYFP) in identified lamprey neurons (ABCs) and in human neuroblastoma (NB2a) cells results in the assembly of exogenous NF180 into ultrastructurally normal NFs that are tightly packed and unphosphorylated. These accumulate in the somata of NB2a cells and produce somatic swelling by 3 days post-transfection. NF180 overexpression in lamprey ABCs in vivo causes exogenous NFs to accumulate in ABC axons, somata, and dendrites, and induces a significant increase in axonal diameter without increasing axonal NF packing density. Overexpression of EYFP alone has none of these effects. We conclude that NF180 normally plays a critical role in determining axonal caliber in ABCs and may influence neuronal size in situations where NFs accumulate in the soma, such as after axonal injury.

Animals↗

PubMed2000

Hypophosphorylated neurofilament subunits undergo axonal transport more rapidly than more extensively phosphorylated subunits in situ.

Axonal transport of neurofilaments (NFs) has long been considered to be regulated by phosphorylation. We present evidence that in optic axons of normal mice, the rate of NF axonal transport is inversely correlated with the NF phosphorylation state. In addition to 200 kDa NF-H and 145 kDa NF-M, axonal cytoskeletons from CNS contained a range of phospho-variants of NF-H migrating between 160-200 kDa, and of NF-M migrating at 97-145 kDa. While 160 kDa phospho-variants of NF-H have been well characterized, we confirmed the identity of the previously-described 97 kDa species as a hypophospho-variant of NF-M since (1) pulse-chase metabolic labeling confirmed the 97 kDa species to be a new synthesis product that was converted by phosphorylation over time into a form migrating at 145 kDa, (2) the 97 kDa protein reacted with multiple NF-M antibodies, including one specific for hypophosphorylated NF-M, and (3) dephosphorylation converted NF-M isoforms to 97 kDa. Autoradiographic analyses following metabolic radiolabeling demonstrated that hypophosphorylated NF-H and NF-M isoforms underwent substantially more rapid transport in situ than did extensively phosphorylated isoforms, while NF-H subunits bearing a developmentally delayed C-terminal phospho-epitope transported at a rate slower than that of total 200 kDa NF-H. Differential transport of phospho-variants also highlights that these variants are not homogeneously distributed among NFs, but are segregated to some extent among distinct, although probably overlapping, NF populations, indicating that axonal NFs are not homogeneous with respect to phosphorylation state.

Animals↗

PubMed2000

Induction of Alzheimer-specific Tau epitope AT100 in apoptotic human fetal astrocytes.

In Alzheimer's and other neurodegenerative diseases, hyperphosphorylated tau accumulates in affected neuronal and glial cells in the form of paired helical filaments (PHFs). This tau binds antibody AT100, which recognizes the double phosphorylation site (Thr212/Ser214) that is not present in normal biopsy tau. In primary cultures, highly enriched (>98%) in astrocytes of human fetal brain, three polypeptides of 52, 64, and 70 kD showed immunoreactivity with tau antibodies against non-phosphorylated epitopes, accounting for 88, 12, and <1%, respectively, of the total reactivity. All three polypeptides were phosphorylated at the PHF-1 epitope but not at the epitopes Tau-1, 12E8, AT8, and AT100. Treatment of cultures with okadaic acid resulted in apoptosis characterized by the blebbing of the plasma membrane, condensation of nuclear chromatin, and fragmentation of the nucleus. This treatment also resulted in a 3- to 5-fold increase in the content of both tau protein and phosphorylation. The increases were observed in all phosphorylation sites examined, and included the AT100 site. The AT100 site has been proposed to be generated by protein kinase B/Akt and Cdc2. Since okadaic acid can induce an AD-like hyperphosphorylated state of normal tau in primary cultures of human brain cells, a simple cellular model is available permitting study of self-aggregation of tau and phosphorylation events characteristic of neurodegeneration.

Alternative Splicing↗

PubMed2000

Entamoeba histolytica: deletion of the GPI anchor signal sequence on the Gal/GalNAc lectin light subunit prevents its assembly into the lectin heterodimer.

Adherence and cytotoxicity of Entamoeba histolytica require the function of a heterodimeric galactose and N-acetylgalactosamine (Gal/GalNAc)-specific lectin. The lectin heavy subunit (Hgl) contains a carbohydrate recognition domain and mediates inside-out cell signaling via its cytoplasmic tail. The function of the lectin light subunit (Lgl) is unknown. The lectin has a unique mechanism of membrane association: Hgl is transmembrane but Lgl is glycosylphosphatidylinositol (GPI) anchored. The role of the GPI anchor signal sequence in heterodimer assembly was tested. Epitope-tagged Lgl with or without the GPI anchor addition signal was expressed in E. histolytica trophozoites. Tagged Lgl did not assemble with Hgl into a lectin heterodimer in the absence of the GPI addition signal. Consistent with previous results that only the Hgl subunit mediates adherence, the monomeric Lgl without the GPI anchor signal lacked Gal/GalNAc-binding activity.

Animals↗

PubMed2000

Increased activity of the hypothalamic-pituitary-adrenal axis of rats exposed to alcohol in utero: role of altered pituitary and hypothalamic function.

Prenatal exposure to ethanol (E) enhances the offspring's ACTH and corticosterone responses to stressors. Here, we determined the role of increased pituitary responsiveness and/or PVN neuronal activity in this phenomenon. Pregnant rats were exposed to E vapors during days 7-18 of gestation, and we compared the responses of their 55- to 60-day-old offspring (E rats) to those of control (C) dams. PVN mRNA levels of the immediate early genes (IEGs) c-fos and NGFI-B, which were low under basal conditions in all groups, showed a peak response 15 min after shocks and 45 min after LPS treatment. These responses were significantly enhanced in E, compared to C offspring of both genders. CRF, but not VP hnRNA levels were also significantly higher in the PVN of shocked E offspring. Resting median eminence content of CRF and VP, and pituitary responsiveness to CRF, were unchanged, while responsiveness to VP was marginally increased in females. These results indicate that prenatal alcohol selectively augments the neuronal activity of hypothalamic CRF perikarya.

Adrenocorticotropic Hormone↗

PubMed2000

Lung isolation for the prevention of air embolism in penetrating lung trauma. A case report.

PURPOSE: To illustrate a new airway and ventilatory management strategy for patients with unilateral penetrating lung injury. Emphasis is placed on avoiding positive pressure ventilation (PPV)-induced systemic air/gas embolism (SAE) through traumatic bronchiole-pulmonary venous fistulas. CLINICAL FEATURES: A 14-yr-old male, stabbed in the left chest, presented with hypovolemia, left hemopneumothorax, an equivocal acute abdomen, and no cardiac or neurological injury. In view of the risk of SAE, we did not ventilate the left lung until any fistulas, if present, had been excised. After pre-oxygenation, general anesthesia was induced and a left-sided double-lumen tube (DLT) was placed to allow right-lung ventilation. Bronchoscopy was performed. The surgeons performed a thorascopic wedge resection of the lacerated lingula. Upon completion of the repair, two-lung ventilation was instituted while the ECG, pulse oximetry, PETCO2, and blood pressure were monitored. Peak inflation pressure was increased slowly and was well tolerated up to 50 cm H2O. The patient's intravascular status was maintained normal. CONCLUSION: Patients with lung trauma are at risk of developing SAE when their lungs are ventilated with PPV. In a unilateral case, expectant non-ventilation of the injured lung until after repair is recommended.

Adolescent↗

PubMed2000

Viral double-stranded RNAs of Eimeria spp. of the domestic fowl: analysis of genetic relatedness and divergence among various strains.

Genetic relatedness was examined among putative viral double-stranded RNA (dsRNA) genomes of Eimeria acervilina, E. maxima, and E. necatrix using Northern hybridization. No cross-hybridization was found among these dsRNAs, revealing little sequence homology, if any. In addition, dsRNAs from eight E. acervulina strains collected from different localities in the United States were also examined for genetic relatedness. The putative viral dsRNAs from these eight strains, including the Guelph strain, hybridized with one another to varying degrees, indicating that they are related but divergent.

Animals↗

PubMed2000

Perirolandic hypoperfusion on single-photon emission computed tomography in term infants with perinatal asphyxia: comparison with MRI and clinical findings.

We describe the findings on single-photon emission computed tomography (SPECT) in patients with perinatal asphyxia at term, with perirolandic cortico-subcortical changes on MRI, and to correlate them with clinical features. SPECT of 7 patients was obtained after injection of 185-370 MBq of Tc-99m-ECD (ethyl cysteinate dimer). The patients had spastic quadriplegia (7/7) with perinatal asphyxia (6/7) at term (7/7). The results were correlated with the MRI findings. Hypoperfusion of the perirolandic cortex was clearly seen on SPECT in all patients, even in two with subtle changes on MRI. SPECT demonstrated a more extensive area of involvement than MRI, notably in the cerebellum (in 4), the thalamus (in 7) and basal ganglia (in 5), where MRI failed to show any abnormalities.

Asphyxia Neonatorum↗

PubMed2000

The mouse Kell blood group gene (Kel): cDNA sequence, genomic organization, expression, and enzymatic function.

The human Kell blood group system is important in transfusion medicine, since Kell is a polymorphic protein and some of its antigens can cause severe reactions if mismatched blood is transfused, while maternal alloimmunization may lead to fetal and neonatal anemia. In humans, Kell is an Mr 93,000 type II membrane glycoprotein with endothelin-3-converting enzyme activity that is linked by a single disulfide bond to another protein, XK, that spans the membrane ten times. An absence of XK leads to clinical symptoms termed the McLeod syndrome. We determined the cDNA sequence of the mouse Kell homologue, the organization of the gene, expression of the protein and its enzymatic function on red cells. Comparison of human and mouse Kell cDNA showed 80% nucleotide and 74% amino acid sequence identity. Notable differences are that the mouse Kell protein has eight probable N-linked carbohydrate side chains, compared to five for human Kell, and that the mouse homologue has one more extracellular cysteine than human Kell protein. The mouse Kell gene (Kel), like its human counterpart, is similarly organized into 19 exons. Kel was located to proximal Chromosome 6. Northern blot analysis showed high expression in spleen and weaker levels in testis and heart. Western blot analysis of red cell membrane proteins demonstrated that mouse Kell glycoprotein has an apparent Mr of 110,000 and, on removal of N-linked sugars, 80,000. As in human red cells, Kell is disulfide-linked to XK and mouse red cells have endothelin-3-converting enzyme activity.

Amino Acid Sequence↗

PubMed2000

HSP16.6 is involved in the development of thermotolerance and thylakoid stability in the unicellular cyanobacterium, Synechocystis sp. PCC 6803.

The low molecular weight (LMW) heat shock protein (HSP), HSP16.6, in the unicellular cyanobacterium, Synechocystis sp. PCC 6803, protects cells from elevated temperatures. A 95% reduction in the survival of mutant cells with an inactivated hsp16.6 was observed after exposure for 1 h at 47 degrees C. Wild-type cell survival was reduced to only 41%. HSP16.6 is also involved in the development of thermotolerance. After a sublethal heat shock at 43 degrees C for 1 h and subsequent challenge exposure at 49 degrees C for 40 min, mutant cells did not survive, while 64% of wild-type cells survived. Ultrastructural changes in the integrity of thylakoid membranes of heat-shocked mutant cells also are discussed. These results demonstrate an important protective role for HSP16.6 in the protection of cells and, in particular, thylakoid membrane against thermal stress.

Cell Membrane↗

PubMed2000

Granular cell tumor of the male breast: report of a case.

We treated a 35-year-old male with a granular cell tumor in the right breast. Physical examination revealed a solid, flattened, round 3.2 x 2.5-cm mass with an irregular surface, covering skin fixation and right axillary lymphadenopathy. Mammography revealed a well-demarcated high-density mass with a minimal starburst appearance. Ultrasonography revealed a hypoechoic, nonhomogeneous mass with an acoustic shadow. Several enlarged lymph nodes in the right axilla were removed at the time of breast tumor excision. Histologically, the tumor featured nests of round or polygonal cells with abundant eosinophilic cytoplasmic granules and small round nuclei, and the enlarged lymph nodes in the right axilla exhibited no metastasis. Immunohistochemically, there was positive staining for S-100 protein, neuron-specific enolase, and vimentin. The tumor also stained for macrophage CD-68, alpha1-antichymotrypsin, and myoglobin. These immunohistochemical findings suggested the tumor cells to be undifferentiated mesenchymal cells which demonstrated the properties of neurogenic cells and histiocytes.

Adenocarcinoma↗

PubMed2000

Effects of intraoperative blood flow on the early patency of radiocephalic fistulas.

The purpose of this study was to find the correlation between intraoperative blood flow and early patency of the radiocephalic fistula. Between March 1998 and March 1999, 50 radiocephalic arteriovenous fistulas were constructed in 41 patients. Intraoperative blood flow measurements were made 10 min after completion of the vascular anastomoses with 3-4 mm handheld flow probes. Patients were followed until failure of fistula or 3 months after the first hemodialysis with these fistulas. Intraoperative blood flow as well as age, gender, presence of diabetes, size of cephalic vein, thrill on the fistula, and flow of radial artery were correlated with early patency. The mean intraoperative blood flow was 174.7 +/- 13.2 mL/min and ranged from 50 to 500 mL/min; it was the only significant parameter that determined early patency of the radiocephalic fistula. Fistulas with flow <160 mL/min (10 of 25) had a higher failure rate than those with flow >160 mL/min (4 of 25), which was statistically significant (p < 0.01). All of the patients with flow <70 mL/min (5 of 5) failed to maintain patency within a month. However, the other variables were not correlated with early patency. We conclude that intraoperative blood flow is a reliable parameter that determines the early patency of radiocephalic fistulas.

Adult↗

PubMed2000

Efficacy of newer medications for treating depression in primary care patients.

PURPOSE: Several medications have recently been introduced for the treatment of depression. We reviewed the literature to summarize their efficacy in the treatment of depression in adult patients in primary care settings. METHODS: We searched the literature published from 1980 to January 1998 using the Cochrane Collaboration Depression Anxiety and Neurosis Group's specialized registry of 8,451 clinical trials, references from trials and 46 pertinent meta-analyses, and consultation with experts. We included randomized controlled trials of at least 6 weeks' duration that measured clinical outcomes and compared one of 32 newer medications with another newer antidepressant, an older antidepressant, a placebo, or a psychosocial intervention for the treatment of depressed patients in primary care settings. The primary outcome was response rate, defined as the proportion of patients experiencing a 50% or greater improvement in depressive symptoms. RESULTS: There were 28 randomized controlled trials involving 5,940 adult primary care patients with major depression, depression requiring treatment, dysthymia, or mixed anxiety depression. Newer agents, including selective serotonin re-uptake inhibitors, serotonin norepinephrine inhibitors, reversible inhibitors of monoamine oxidase, and dopamine antagonists, were usually compared with tricyclic agents. Average response rates were 63% for newer agents, 35% for placebo, and 60% for tricyclic agents. Newer agents were significantly more effective than placebo [risk ratio = 1.6; 95% confidence interval (CI), 1.2 to 2.1), but similar to tricyclic agents (risk ratio = 1.0; 95% CI, 0.9 to 1.1). Response rates were similar in the different types of depressive disorders, except that two small trials in frail older patients showed no significant effects of newer agents compared with placebo. Dropout rates as a result of adverse effects were 8% with newer agents and 13% with tricyclic agents (P <0.05). CONCLUSIONS: In primary care settings, newer antidepressants are more effective than placebo and have similar efficacy compared with tricyclic agents in the acute treatment of depression. Dropout rates as a result of adverse effects are lower with newer compared with tricyclic agents. Future studies should compare the effectiveness of different therapies among primary care patients with less severe depression and greater medical and psychiatric comorbidity.

Antidepressive Agents, Second-Generation↗

PubMed2000

Cation-binding sites of subtilisin Carlsberg probed with Eu(III) luminescence.

Two Ca(2+)-binding sites of subtilisin Carlsberg are studied by monitoring static and time-resolved luminescence of selectively substituted Eu(3+) at each site, and they are found to be characteristically quite different from each other. Compared with the coordination sphere of free Eu(3+), two sites are very similar to each other, so that both have a well-defined binding structure with low coordination symmetry. However, compared with the weak site, the strong site is relatively more polar, more symmetrical, and more easily accessible. Furthermore, despite the absence of water reported in the x-ray crystal structure (, Eur. J. Biochem. 166:673-692), one water molecule is found to exist in the coordination sphere of the strong site in aqueous solution. Thus it is suggested that in solution the Ca(2+) bound in the strong site forms an additional coordination bond to a solvent or substrate molecule.

Bacillus↗

PubMed2000

Stress, coping, and depression in non-ulcer dyspepsia patients.

Thirty adults with upper gastrointestinal symptoms in the absence of structural organic disease diagnosed with non-ulcer dyspepsia (NUD) were compared to 30 healthy adults who had visited the hepatobiliary clinic for medical evaluation of non-organic complaints without NUD. Medical investigation in both groups were negative. Before independent gastrointestinal physicians conducted diagnostic evaluations, all subjects were evaluated for anxiety and depressive symptoms, stressful life events, coping style, and social support. The measures included Symptom Checklist 90-Revised (SCL-90-R), Beck Depression Inventory (BDI), Spielberger State-Trait Anxiety Inventory (STAI), Ways of Coping Checklist, and Interpersonal Support Evaluation List, and a self-report questionnaire, which measured the quantity of perceived stressful life events. The NUD patients reported significantly more symptoms of depression, more perceived stressful life events, less problem-focused coping, and less social support than the control subjects. Depressive symptoms were negatively correlated with interpersonal support, whereas, problem-focused coping was positively correlated with interpersonal support in the NUD patients. The two groups did not differ significantly in terms of anxiety and emotion-focused coping. The implications of these findings for the diagnosis and treatment of NUD are discussed.

Adaptation, Psychological↗

PubMed2000

The Kell blood group system: Kell and XK membrane proteins.

Two membrane proteins express the antigens that comprise the Kell blood group system. A single antigen, Kx, is carried on XK, a 440-amino acid protein that spans the membrane 10 times, and more than 20 antigens reside on Kell, a 93-kd, type II glycoprotein. XK and Kell are linked, close to the membrane surface, by a single disulfide bond between Kell cysteine 72 and XK cysteine 347. Although primarily expressed in erythroid tissues, Kell and XK are also present in many other tissues. The polymorphic forms of Kell are due to single base mutations that encode different amino acids. Some Kell antigens are highly immunogenic and may cause strong reactions if mismatched blood is transfused and severe fetal anemia in sensitized mothers. Antibodies to KEL1 may suppress erythropoiesis at the progenitor level, leading to fetal anemia. The cellular functions of Kell/XK are complex. Absence of XK, the McLeod phenotype, is associated with acanthocytic red blood cells (RBCs), and with late-onset forms of muscular dystrophy and nerve abnormalities. Kell, by homology, is a member of the neprilysin (M13) family of membrane zinc endopeptidases and it preferentially activates endothelin-3 by specific cleavage of the Trp21-Ile22 bond of big endothelin-3.

Amino Acid Transport Systems, Neutral↗