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Biomedical subjects

S Li

Publications and source records attributed to S Li.

At least 487 records · Page 27Linked to original sources
PubMed2000

CYP11B2 expression in rat liver and the effect of spironolactone on hepatic fibrogenesis.

OBJECTIVE: In consideration of the hypothetical possibility that locally produced aldosterone is likely to take an active part in fibrogenesis of the liver, we undertook the present study to investigate the expression of aldosterone synthase gene CYP11B2 in rat liver and the curative effect of spironolactone on fibrosis of the liver. METHODS AND MATERIALS: 160 Wistar rats weighing about 250 g were divided into four groups as follows: model group, spironolactone group, malotilate group and control group. After 2, 4, 6, 8 and 10 weeks, the animals were sacrificed. Morphological examination was based on microscopic and electron microscopic findings. The area of collagen was examined by an Image Analyse System (Leica). By means of reverse transcriptase-polymerase chain reaction and in situ hybridization, the expression of CYP11B2 was detected. RESULTS: The expression of CYP11B2 mRNA, which was localized in the endoplasm of fat-storing cells, was upregulated when fibrogenesis occurred. The grade of fibrosis and the area of collagen in the spironolactone group were less than those in the model group before the 6th week (p < 0.05). After the 6th week, there was no significant difference between the spironolactone group and the model group (p > 0.05). CONCLUSIONS: The expression of CYP11B2 mRNA is upregulated in fibrotic liver. Spironolactone can partly have a fibrogenesis-inhibiting effect in the early stage of CCl(4)-induced hepatic fibrogenesis.

Animals↗
PubMed2000

Essential contribution of intron sequences to Ca(2+)-dependent activation of c-fos transcription in pituitary cells.

In pituitary cells, c-fos transcription induced by releasing hormones and growth factors results from enhanced initiation of transcription, and sustained elongation of transcripts beyond the first intron. We studied the regulatory role of the first intron of the mouse c-fos gene for the control of its transcription in rat pituitary cells. We showed that the intron contains a block to elongation which is relieved by physiological activators TRH and EGF. By expressing luciferase under the control of the c-fos promoter including the first intron in reporter gene constructs, we demonstrate enhancement of TRH and EGF transcriptional stimulation by intron sequences. Further analysis of Ca(2+) signalling-depending transcription showed that the intron contains control elements in addition to the block to elongation, and that sequences in the first intron can mediate Ca(2+)-stimulated transcription also with a minimal or the SV40 promoter, irrespective of the presence or absence of the intronic block site. Within the c-fos promoter the serum response element and the cAMP response element play a permissive role in Ca(2+)- and cAMP-enhanced transcription of intron containing reporter genes. Specific binding of nuclear proteins to a consensus enhancer binding site (Sp1) within the first intron of c-fos was demonstrated, which might reflect one of the mechanisms that link Ca(2+) and intron sequences to c-fos expression. These findings point towards important functions of intronic sequences in gene transcription control.

Animals↗
PubMed2000

Epidermal growth factor receptor expression in neurofibromatosis type 1-related tumors and NF1 animal models.

We have found that EGF-R expression is associated with the development of the Schwann cell-derived tumors characteristic of neurofibromatosis type 1 (NF1) and in animal models of this disease. This is surprising, because Schwann cells normally lack EGF-R and respond to ligands other than EGF. Nevertheless, immunoblotting, Northern analysis, and immunohistochemistry revealed that each of 3 malignant peripheral nerve sheath tumor (MPNST) cell lines from NF1 patients expressed the EGF-R, as did 7 of 7 other primary MPNSTs, a non-NF1 MPNST cell line, and the S100(+) cells from each of 9 benign neurofibromas. Furthermore, transformed derivatives of Schwann cells from NF1(-/-) mouse embryos also expressed the EGF-R. All of the cells or cell lines expressing EGF-R responded to EGF by activation of downstream signaling pathways. Thus, EGF-R expression may play an important role in NF1 tumorigenesis and Schwann cell transformation. Consistent with this hypothesis, growth of NF1 MPNST lines and the transformed NF1(-/-) mouse embryo Schwann cells was greatly stimulated by EGF in vitro and could be blocked by agents that antagonize EGF-R function.

Animals↗
PubMed2000

Protective factors against suicidal acts in major depression: reasons for living.

OBJECTIVE: Over 30,000 people a year commit suicide in the United States. Prior attempted suicide and hopelessness are the most powerful clinical predictors of future completed suicide. The authors hypothesized that "reasons for living" might protect or restrain patients with major depression from making a suicide attempt. METHOD: Inpatients with DSM-III-R major depression were assessed for depression, general psychopathology, suicide history, reasons for living, and hopelessness. Of the 84 patients, 45 had attempted suicide and 39 had not. RESULTS: The depressed patients who had not attempted suicide expressed more feelings of responsibility toward family, more fear of social disapproval, more moral objections to suicide, greater survival and coping skills, and a greater fear of suicide than the depressed patients who had attempted suicide. Scores for hopelessness, subjective depression, and suicidal ideation were significantly higher for the suicide attempters. Reasons for living correlated inversely with the combined score on these measures, considered an indicator of "clinical suicidality." Neither objective severity of depression nor quantity of recent life events differed between the two groups. CONCLUSIONS: During a depressive episode, the subjective perception of stressful life events may be more germane to suicidal expression than the objective quantity of such events. A more optimistic perceptual set, despite equivalent objective severity of depression, may modify hopelessness and may protect against suicidal behavior during periods of risk, such as major depression. Assessment of reasons for living should be included in the evaluation of suicidal patients.

Adaptation, Psychological↗
PubMed2000

Perimenopause and the quality of life.

The purposes of this study are to describe the frequency and distress of symptoms associated with perimenopause, to examine the changes in the quality of life (QOL) related to perimenopause, and to examine the relationships between symptoms associated with perimenopause and the QOL. A cross-sectional, correlational design was employed. Two hundred fourteen perimenopausal women completed the Women's Health Assessment Scale (WHAS) and the Quality of Life Scale. It was found that vasomotor symptoms were not central to the list of symptoms associated with perimenopause. More women reported psychosomatic complaints as opposed to vasomotor complaints. Compared to the premenopausal period, women during perimenopause experienced slightly, yet significantly decreased, levels of QOL. Multiple regression analysis demonstrated that the psychosomatic symptom category was the sole predictor of the QOL during perimenopause. In summary, psychosomatic symptoms occur most frequently and are most distressful for perimenopausal women in this study. It may be important to manage psychosomatic symptoms to improve the QOL for perimenopausal women.

Adult↗
PubMed2000

Mediating factors in dietary change: understanding the impact of a worksite nutrition intervention.

This report, based on 1,795 participants in the Next Step Trial, examines how a dietary intervention program affected mediating factors for dietary change. The model tested whether intervention increased predisposing (skills, knowledge, and beliefs) and enabling (social support and norms) factors for change and advanced participants into action and maintenance stages of change. The intervention significantly increased both predisposing factors for dietary change and the likelihood of moving into or remaining in action and maintenance stages of change. Changes in predisposing and enabling factors and stage of change at follow-up (regardless of stage at baseline) were associated with significant dietary change. Changes in mediating variables explained between 34% and 55% of the effects of the dietary intervention. These results support the value of measuring mediating factors as part of dietary intervention evaluations and suggest that interventions that target norms and eating environments in addition to skills and knowledge may further increase intervention effectiveness.

Adult↗
PubMed2000

Jones-matrix analysis with Pauli matrices: application to ellipsometry

The coherency matrix formalism based on Pauli matrices is applied to analyze a general ellipsometer that is described by Jones matrices. Here the Jones matrices are represented as sums of appropriate coefficients times the Pauli matrices and the identity matrix, and intensities are represented as traces of coherency matrices. This approach allows us not only to treat partial polarizations explicitly but also to take advantage of various identities to reduce to algebra the operations necessary for system analysis. A general expression is obtained for the intensity transmitted through a polarizer-sample-compensator-analyzer (PSCA) ellipsometer. This general expression is applied to an ideal PSCA ellipsometer, and then the results are reduced to describe several simpler but commonly used configurations. The results provide insight regarding general capabilities and limitations and allow us to compare different ellipsometer systems directly. Finally, this expression is extended to include artifacts, the explicit representation of which allows a complete determination of their defects.

Journal Article↗
PubMed2000

Validation of a single-item measure of usual physical activity.

The purpose of this study was to assess the reliability and validity of a single-item measure of Usual Physical Activity and to assess its usefulness as a physical activity tool for perimenopausal women. 188 perimenopausal women participated (age: M = 47 yr., SD = 3; range = 40-55). Data were collected using the Women's Health Assessment Scale, the Physical Activity Questionnaire, the Perimenopause-related Quality of Life Scale, a health history and demographic questionnaire, and the rater. Scores were stable over a 2-wk. interval. Convergent validity was supported by a correlation of .66 between ratings on Usual Physical Activity and the Physical Activity Questionnaire. Concurrent validity was supported by the association of the rating of Usual Physical Activity with three parameters of Body Mass Index, psychosomatic symptoms, and perimenopause related quality of life, known to be associated with physical activity. Highly active women had a lower Body Mass Index than less active and inactive women. Active women tended to report fewer and less distressing psychosomatic symptoms and better quality of life. These findings support the use of rating of Usual Physical Activity to classify perimenopausal women into categories of physical activity.

Adult↗
PubMed2000

Differences in protein kinase C and estrogen receptor alpha, beta expression and signaling correlate with apoptotic sensitivity of MCF-7 breast cancer cell variants.

Widespread use of MCF-7 human breast cancer cells as a model system for breast cancer has lead to variations in these cells between different laboratories. Although several reports have addressed these differences in terms of proliferation and estrogenic response, differences in sensitivity to apoptosis have just begun to be described. Based on the possible differences in apoptotic sensitivity that may arise due to the existence of MCF-7 cell variants, we determined the relative sensitivity of MCF-7 cell variants from three established laboratories (designated M, L and N) to known inducers of apoptosis. Consistent with our previous studies we demonstrate that differences exist among these variants in regards to tumor necrosis factor alpha (TNF)-induced cell death and inhibition of proliferation in a dose-dependent manner. To establish if the difference in apoptotic susceptibility was specific to TNF, the three MCF-7 cell variants were tested for their response to other known inducers of apoptosis: okadaic acid, staurosporine and 4-hydroxy-tamoxifen. Viability and DNA fragmentation analysis revealed a similar pattern of resistance to apoptosis by all agents in the MCF-7 M variant. The MCF-7 L variant was resistant to okadaic acid and 4-hydroxy-tamoxifen but not staurosporine. In contrast, MCF-7 N cells were sensitive to induction of apoptosis by all agents. The role of both protein kinase C (PKC) and estrogen signaling in the regulation of cell survival prompted investigation of these pathways as a mechanism for differential sensitivity of MCF-7 cell variants to apoptosis. While both estrogen receptor alpha (ERalpha) and ERbeta were expressed in MCF-7 M and N cells, the absence of ERbeta in MCF-7 L cells correlated with decreased estrogen responsiveness of the L variant. Variations in estrogenic responsiveness and PKC isoform expression may account for the enhanced susceptibility of both the L and N variants to staurosporine.

Apoptosis↗
PubMed2000

Immunochemical detection of molds: a review.

Molds are widely distributed in nature and cause deterioration of foods and feeds. Their mycotoxins can adversely affect human and animal health. Suitable assays for molds, therefore, are required to implement control and regulatory strategies and to develop appropriate feeding regimens for mold-infested feeds. Many different types of mold assays have been used, most of which are not reproducible or accurate. However, the immunoassays, particularly enzyme-linked immunosorbent assays (ELISAs), can be especially useful. Among these, assays that detect the water-soluble extracellular secretions of fungi, the exoantigens, are generally able to detect fungi at the genus or species level, whereas the heat-stable polysaccharides tend to be specific for one or more genus of fungi. Several species and genus (genera)-specific ELISAs have been developed using monoclonal or polyclonal antibodies against exoantigens and heat-stable polysaccharides from a wide range of fungi, including Aspergillus, Penicillium, and Fusarium species. Other assays have been developed that nonspecifically detect mold in food or feed, some using antibodies against a mixture of antigens from different fungi. These assays are highly sensitive, are easy to perform, and provide an index of the amount of mold present in the sample. Further refinement of these assays should facilitate their widespread use by food and feed processors, regulatory agencies, taxonomists, and research scientists.

Animals↗
PubMed2000

Worrisome histologic alterations following fine-needle aspiration of benign parotid lesions.

OBJECTIVE: To describe the histologic changes associated with preoperative fine-needle aspiration biopsies of benign parotid lesions and the features that distinguish these changes from malignant neoplasms. MATERIALS AND METHODS: Ten benign parotid lesions with a recent history of preoperative fine-needle aspiration were selected, including pleomorphic adenoma (4 cases), oncocytic adenoma (3 cases), myoepithelioma (1 case), Warthin tumor (1 case), and lymphoepithelial cyst (1 case). RESULTS: A spectrum of histologic alterations were observed. Alterations included squamous cell metaplasia (8 cases), infarction and necrosis (4 cases), subepithelial stromal hyalinization (3 cases), acute and chronic hemorrhage and inflammation with multinucleated giant cells (all cases), granulation tissue with subsequent fibrosis (all cases), cholesterol cleft formation (1 case), pseudoxanthomatous reaction (1 case), pseudocapsular invasion (1 case), and microcystic degeneration (2 cases). In cases with exuberant squamous metaplasia, necrosis, or subepithelial stromal hyalinization, a diagnosis of squamous cell carcinoma or low-grade mucoepidermoid carcinoma was seriously considered. CONCLUSIONS: Knowledge of a previous fine-needle aspiration procedure and awareness of its effects on histology of the subsequent parotidectomy specimens are necessary to avoid potential misdiagnosis.

Adolescent↗
PubMed2000

Essentiality of intron control in the induction of c-fos by glucose and glucoincretin peptides in INS-1 beta-cells.

Glucose controls long-term processes in the pancreatic beta-cell such as metabolic enzymes gene expression, cell growth, and apoptosis. Such control is likely mediated via the expression of immediate-early response genes since several of these genes including c-fos are strongly induced by glucose in the beta-cell line INS-1, provided costimulation with cAMP-raising glucoincretin hormones. This study addresses the mechanism of c-fos gene activation by glucose. Glucose in the presence of chlorophenylthio-cAMP generated a low threefold induction of the c-fos/basic luciferase reporter gene, which includes only the c-fos promoter. In contrast, the c-fos/intron construct containing the first intron in addition to promoter elements showed a pronounced 16-fold induction, comparable to the increased c-fos mRNA accumulation. Similar observations were made with glucose in combination with the glucoincretins glucagon-like peptide 1, glucose-dependent insulinotropic polypeptide, and pituitary adenylyl cyclase-activating peptide 38. Deletion of a 119 bp region in intron 1 that includes a transcriptional arrest site did not affect the inductive process. In contrast, a 534 bp deletion comprising a major part of the intron reduced the induction by 75%. At the promoter level, mutating the cAMP response element reduced by more than 60% the transcriptional activation whereas mutating the serum response element had no effect. Inhibitors of protein kinase A and Ca(2+)/calmodulin-dependent protein kinases each reduced by 50% the reporter gene activation and together fully prevented the glucose-glucoincretin effect. In conclusion, the strong induction of c-fos by glucose and glucoincretins results from Ca(2+) and cAMP signaling pathways addressing both the CRE in the promoter and essential response element(s) in the first intron that are unrelated to the transcription arrest site.

Base Sequence↗
PubMed2000

Brassica vegetables increase and apiaceous vegetables decrease cytochrome P450 1A2 activity in humans: changes in caffeine metabolite ratios in response to controlled vegetable diets.

Induction or inhibition of biotransformation enzymes, enzymes that activate or detoxify numerous xenobiotics, is one mechanism by which vegetables may alter cancer risk. Using a randomized crossover design, we examined the effect of various vegetable diets on cytochrome P450 (CYP) 1A2, N-acetyltransferase 2 (NAT2) and xanthine oxidase activity in humans. Men and women, non-smokers, on no medication and 20-40 years of age ate four 6-day controlled diets: basal (vegetable-free) and basal with three botanically defined vegetable groups. Enzyme activities were determined by measuring urinary caffeine metabolite ratios after a 200 mg caffeine dose on the last day of each feeding period. Mean CYP1A2 activity for 19 men and 17 women (least squares means adjusted for sex, GSTM1 genotype, urine volume and feeding period) with basal, brassica, allium and apiaceous vegetable diets differed significantly (P </=ISOdia</= 0. 0005) by diet, irrespective of the caffeine metabolite molar ratio used to describe CYP1A2 activity; brassica vegetables increased (P <0.04) and apiaceous vegetables decreased (P </=ISOdia</= 0.02) activity compared with the basal and allium diets. There was no effect of diet on NAT2 and xanthine oxidase activities and none of the subjects differed by GSTM1 genotype. These results demonstrate that while one vegetable subgroup induces human CYP1A2 activity, another subgroup inhibits it. This points to a complex association between consumption of a typical diet of various vegetables and biotransformation enzyme activities in humans, an association that may be difficult to interpret in observational studies.

Adult↗
PubMed2000

Modulation of human glutathione S-transferases by botanically defined vegetable diets.

Glutathione S-transferases (GSTs) conjugate activated xenobiotics with glutathione; thus, GST induction may improve detoxification and excretion of potentially harmful compounds. Using a randomized cross-over design, we tested the hypothesis that, in humans, serum GST-alpha concentration (GST-alpha) and GST activity increase with vegetable consumption and that this effect is GSTM1 genotype dependent. Twenty-one men (10 GSTM1-null and 11 GSTM1+) and 22 women (15 GSTM1-null and 7 GSTM1+), nonsmokers, 20-40 years of age and not on medications, ate four 6-day controlled diets: basal (vegetable-free), and basal supplemented with three botanically defined groups of vegetables (i.e., brassica, allium, and apiaceous). Fasting blood samples, collected on the last 2 days of each feeding period, were analyzed for GST-alpha, serum GST activity [against 1-chloro-2,4-dinitrobenzene (CDNB) and 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl)] and peripheral-lymphocyte GST-mu activity (against trans-stilbene oxide). The brassica, but not allium or apiaceous, vegetable diets (relative to the basal diet) increased GST-alpha by 26% (P = 0.005) and GST (NBD-Cl) activity by 7% (P = 0.02) in the GSTM1-null individuals, particularly the women. Apiaceous vegetable supplementation decreased GST-alpha in the GSTM1+ men (P = 0.03). Among the GSTM1+ women, both brassica and the allium diets increased GST-mu activity by 18% (P = 0.02) and 26% (P = 0.001), respectively. The vegetable diets had no effect on GST (CDNB) activity, irrespective of GSTM1 genotype or sex. These results demonstrate that GSTM1 genotype has a significant effect on GST responses to diet and that brassica vegetables are most effective at inducing GST-alpha, whereas both brassica and allium vegetables induce GST-mu. GST responses were more pronounced in women than men, but it is not clear from this study whether this is a dose-per-body-weight or a sex-specific effect.

Adult↗
PubMed2000

High dose, alternate day corticosteroids for systemic onset juvenile rheumatoid arthritis.

OBJECTIVE: To determine the safety and efficacy of high dose alternate day (qod) prednisone as therapy in acute systemic onset JRA (SOJRA). METHODS: A retrospective chart review was performed of all active patients with SOJRA at our institutions who began high dose qod prednisone (n = 20; 9 male, 11 female; mean age of onset 6.5 yrs, range 1.2-18.6). Patients were followed for at least one year after initiation of high dose qod prednisone. Disease activity (fever, rash, active joint count, complete blood cell count, erythrocyte sedimentation rate, ESR) and possible side effects of treatment were assessed at each visit. RESULTS: Within a mean of 2.1 months (range 1-5), systemic features (fever, rash, serositis, coagulopathy) in all patients had resolved and there was significant improvement in laboratory indices of disease activity. Doses ranged from 1 to 5.8 mg/kg qod (actual doses: 50-400 mg qod), with a mean of 3.2 mg/kg. No patient had to restart daily prednisone. The only major side effect was the development of mild cataracts in one patient. Height standard deviation scores (SDS) remained within normal range in all but 2 patients. Clinical improvement was maintained in all patients, as measured by lack of systemic symptoms, and decreased active joint count. Repeated measures of analysis of variance revealed significant improvement in all laboratory tests (white blood cell count, hemoglobin, platelet count, ESR) measured at 0, 6, and 12 months (p < 0.001). Nine of the 20 patients continued qod prednisone more than 12 months beyond the study period (mean 5.2 yrs, range 3-8). The only additional side effects were a vertebral crush fracture in one patient and possible avascular necrosis in another. Height SDS did not change significantly over the 3 year period after the initiation of qod prednisone (p > 0.05). CONCLUSION: High dose qod prednisone appears to be effective in controlling the systemic features of SOJRA and was well tolerated. Side effects attributable to corticosteroids, including growth suppression, were minimal.

Adolescent↗
PubMed2000

The level of HIV infection of macrophages is determined by interaction of viral and host cell genotypes.

The outcome of HIV infection in vivo and in vitro depends on the interaction of viral and cellular genotypes. Analysis of infection of blood monocyte-derived macrophages by primary HIV strains shows that approximately one-third of 32 isolates was consistently high-replicating, one-third was consistently low-replicating, and one-third was dependent on the donor of the macrophages (i.e., variable). HIV isolates from patients with AIDS showed enhanced replication within macrophages and predominant use of CCR5 for entry, although 13% did use CXCR4. Tissue isolates from brain and CSF showed an enhanced ability to infect 1-day-old monocytes compared with blood isolates from patients with AIDS. The ability of primary isolates to infect neonatal or adult monocytes maturing into macrophages or placental macrophages correlated directly with the extent of CCR5 expression. Studies of macrophages from pairs of identical twins and unrelated donors showed genetic control over CCR5 expression, which was independent of the CCR5delta32 genotype. Furthermore, these studies showed a marked host-cell genetic effect on the variable primary HIV strains. Although CCR5 was essential for the entry of most primary isolates, it was not the essential "bottleneck" determining productivity of infection. The location of this bottleneck in the HIV replication cycle differs according to viral strain and host-cell donor, but it was exerted before the stage of reverse transcription in 80-90% of cases. Such host-cell genetic factors may affect viral load in vivo where macrophages are the predominant target cells.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Two hundred and seventeen cases of winter diseases treated with acupoint stimulation in summer.

217 cases of chronic bronchitis and asthma were clinically treated and analyzed for the effects of combining electric stimulation with topical application of drug on acupoints. The results suggested that the combined therapy was superior to unitary therapy (P < 0.05). It is indicated that the combined therapy has a good curative effect in both short- and long-terms.

Acupuncture Points↗