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Biomedical subjects

S Lu

Publications and source records attributed to S Lu.

At least 37 records · Page 2Linked to original sources
PubMed2001

VEGF expression in skin warts. Relevance to angiogenesis and vasodilation.

Verrucae vulgaris (skin warts) are benign proliferative lesions which are generally associated with human papillomavirus type 2 (HPV-2) infection. Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen able to induce angiogenesis and vasodilation. Our previous findings indicate that these two processes take place during the formation of skin warts. The purpose of this study was to determine whether VEGF expression in these lesions was associated with HPV infection, angiogenesis or vasodilation. To this end, paraffin-embedded specimens of skin warts which were either negative for HPV-1, -2, -3 and -4 (HPV-; n = 18), or positive for HPV-2 (HPV+; n = 21) were compared with histologically normal perilesional skin (n = 13). Serial sections were stained with antibodies to von Willebrand Factor (vWF) and to VEGF. Vascularity was quantified by point counting vWF-positive blood vessels. Small and large vessels were quantified separately, using a cut-off value of 50 microm diameter. VEGF expression in the epidermis was estimated by consensus of two independent observers according to three indices: (1) percentage of cells stained, (2) intensity of the staining, and (3) product of area and intensity (final score). Results were analysed by nonparametric tests. Similar levels of VEGF were found in specimens of normal skin, HPV- and HPV+ warts, irrespective of the index used. There was no significant correlation between VEGF expression and vascularity values for either small or large vessels. These results indicate that, on its own, VEGF expression is not associated with angiogenesis, vasodilation or HPV infection in skin warts. The presence of VEGF in normal skin suggests that it may play a role in tissue homeostasis.

Blood Vessels↗
PubMed2001

Abnormal DNA-binding of transcription factors in minimal change nephrotic syndrome.

The activation of transcription factors such as nuclear factor kappaB (NF-kappaB) and activator protein 1 (AP-1) plays an important role in regulating the expression of target genes, including those for cytokines involved in pathogenesis of minimal change nephrotic syndrome (MCNS). The therapeutic effects of glucocorticoids depend on the glucocorticoid receptor (GR) acting on gene transcription and interacting with certain transcription factors. To explore the role of transcription factors in the pathogenesis of MCNS and the therapeutic effects of glucocorticoids, we examined the DNA-binding abilities of NF-kappaB, AP-1, and GR in peripheral blood mononuclear cells (PBMC) from 6 children with MCNS and 6 healthy controls by electrophoretic mobility shift assay (EMSA). NF-kappaB and AP-1 DNA-binding abilities were significantly increased both at baseline and after stimulation by phorbol 12-myristate 13-acetate (TPA) in PBMC from MCNS patients compared with controls, but declined to normal levels after treatment with dexamethasone (DEX). GR DNA-binding abilities were significantly reduced at baseline and after treatment with TPA, but were enhanced markedly by DEX. There were strong correlations between urinary protein and the baseline DNA binding ability of NF-kappaB or AP-1, or GR. These results suggested that the abnormal activation of NF-kappaB and AP-1 and the reduction of GR DNA-binding abilities may be involved in the pathogenesis of MCNS. Inhibition of NF-kappaB and AP-1 and enhancement of GR DNA-binding abilities by DEX may form the molecular basis of the effects of glucocorticoids in MCNS.

Child↗
PubMed2001

Regulation of intestinal apolipoprotein A-I synthesis by dietary phosphatidylcholine in newborn swine.

Phospholipid (PL) from both dietary sources and biliary secretions may be important in the regulation of intestinal apolipoprotein (apo) synthesis. We previously demonstrated the up-regulation of apo A-I secretion by phosphatidylcholine (PC) in a newborn piglet intestinal epithelial cell line. We hypothesized that dietary PC increases small intestinal apo A-I synthesis in vivo in the newborn piglet. Two-day-old female swine were fed by gavage for 48 h. Diets consisted of a formula containing 51% of calories as triacylglycerol providing 180 kcal/kg/24 h. The experimental group (+PC, n = 7) received 1 g/L added soybean PC, and the control group (-PC, n = 7) received no added PC. At the end of the study period, jejunal apo A-I, B, and A-IV synthesis was measured, and apo A-I mRNA levels were quantitated. Jejunal mucosal PL content and serum lipids and apo B and A-I levels were measured. Jejunal apo A-I synthesis was almost twice as high in the +PC group as compared to the -PC group with no difference in apo A-I mRNA levels. Jejunal content of PL was higher in the +PC group than in the -PC group. There were no differences in jejunal apo B and A-IV synthesis or serum levels of lipids and apo-lipoproteins between the two groups. Dietary PC supplementation in newborn swine up-regulated jejunal apo A-I synthesis. Apo A-IV synthesis, which is sensitive to fatty acid flux, was not significantly increased, which suggests a specific effect of PC on apo A-I synthesis. Lumenal PC may be important in the regulation of intestinal apo A-I synthesis in the neonate.

Animals↗
PubMed2001

Use of oral montelukast in the treatment of asthma.

Montelukast, a new leukotriene modifier, has several benefits in the treatment of asthma in adults and children including improved relief of asthma symptoms, rapid onset, a safety profile comparable with placebo, and oral, once-daily dosing means excellent adherence.

Acetates↗
PubMed2001

Arthritis induced in rats with nonimmunogenic adjuvants as models for rheumatoid arthritis.

Rat models are useful for studies of the pathogenesis of rheumatoid arthritis (RA) since rats are extraordinarily sensitive to induction of arthritis with adjuvants. Injection of not only the classical complete Freund's adjuvant but also mineral oil without mycobacteria and pure adjuvants such as pristane and squalene, induce severe arthritis in many rat strains. Models like pristane-induced arthritis in rats are optimal models for RA since they fulfill the RA criteria including a chronic relapsing disease course. Arthritogenic adjuvants like pristane, avridine, squalene and mineral oil are not immunogenic since they do not contain major histocompatibility complex (MHC) binding peptides. Nevertheless, the diseases are MHC-associated and dependent on the activation of alphabetaTCR (T-cell receptor)-expressing T cells. However, it has not been possible to link the immune response to joint antigens or other endogenous components although immunization with various cartilage proteins induce arthritis but with different pathogeneses. To unravel the mechanisms behind adjuvant-induced arthritis, a disease-oriented genetic approach is optimal. Several loci that control onset of arthritis, severity and chronicity of the disease have been identified in genetic crosses and most of these have been confirmed in congenic strains. In addition, many of these loci are found in other autoimmune models in the rat as well as associated with arthritis in mice and humans.

Adjuvants, Immunologic↗
PubMed2001

Recombinant Mycobacterium tuberculosis protein associated with mammalian cell entry.

The ability to gain entry and resist the antimicrobial intracellular environment of mammalian cells is an essential virulence property of Mycobacterium tuberculosis. A purified recombinant protein expressed by a 1362 bp locus (mce1) in the M. tuberculosis genome promoted uptake into HeLa cells of polystyrene latex microspheres coated with the protein. N-terminus deletion constructs of Mce1 identified a domain located between amino acid positions 106 and 163 that was needed for this cell uptake activity. Mce1 contained hydrophobic stretches at the N-terminus predictive of a signal sequence, and colloidal gold immunoelectron microscopy indicated that the corresponding native protein is expressed on the surface of the M. tuberculosis organism. The complete M. tuberculosis genome sequence revealed that it contained four homologues of mce (mce1, mce2, mce3, mce4) and that they were all located within operons composed of genes arranged similarly at different locations in the chromosome. Recombinant Mce2, which had the highest level of identity (67%) to Mce1, was unable to promote the association of microspheres with HeLa cells. Although the exact function of Mce1 is still unknown, it appears to serve as an effector molecule expressed on the surface of M. tuberculosis that is capable of eliciting plasma membrane perturbations in non-phagocytic mammalian cells.

Antibodies, Bacterial↗
PubMed2001

Thyroid stimulating hormone downregulates vascular endothelial growth factor expression in FRTL-5 cells.

We studied the regulation of the expression of vascular endothelial growth factor (VEGF) by TSH in monolayer cultures of rat thyroid FRTL-5 cell lines. The VEGF mRNA synthesis was significantly inhibited by TSH as well as dibutyryl cyclic adenosine monophosphate (cAMP) in a dose-dependent manner in FRTL-5 cells. This observation is contrary to previously published results using the thyroid follicular culture system. Our results suggest that the direct effect of TSH/cAMP is to inhibit the VEGF synthesis in monolayer cells.

Animals↗
PubMed2001

Comparison of AIDS progression and survival in persons with pulmonary versus extrapulmonary tuberculosis in Los Angeles.

The objective of this research was to compare the demographics, acquired immune deficiency syndrome (AIDS) progression, and survival in persons with AIDS with pulmonary tuberculosis (PTB) versus extrapulmonary tuberculosis (EPTB), because there are limited population-based data on this topic. A population-based longitudinal study with 3 years of follow-up was performed. Data were collected every 6 months from medical records of persons with AIDS and TB treated at private and public medical facilities throughout Los Angeles County (LAC). Participants included a population-based sample of 216 persons with AIDS and PTB and 166 persons with AIDS and EPTB (including 113 persons with both PTB and EPTB), with an AIDS diagnosis reported in 1993. Compared to persons with AIDS with PTB, persons with AIDS and EPTB were 2.2 times more likely to be Latino than white (95% confidence intervals [CIs]: 1.2, 4.0) and 1.7 times more likely to be foreign-born (95% CIs: 1.1, 2.5). Compared to persons with AIDS with PTB, persons with AIDS and EPTB had similar antiretroviral and PCP prophylaxis use; lower CD4 counts at time of AIDS diagnosis (p = 0.0004); no differences in CD4 counts over the total follow-up period (p = 0.4); higher rates of total opportunistic infections (OIs) (incidence density ratio [IDR] = 2.0; 95% CIs: 1.6, 2.4); and comparable survival curves (p = 0.07). Persons with AIDS and EPTB had a more complicated medical course with lower CD4 counts at time of AIDS diagnosis and more OIs over the follow-up period than persons with AIDS and PTB, however the survival profiles for the two groups were comparable.

AIDS-Related Opportunistic Infections↗
PubMed2001

Structural analysis of free and enzyme-bound amaranth alpha-amylase inhibitor: classification within the knottin fold superfamily and analysis of its functional flexibility.

The three-dimensional structure of the amaranth alpha-amylase inhibitor (AAI) adopts a knottin fold of abcabc topology. Upon binding to alpha-amylase, it adopts a more compact conformation characterized by an increased number of intramolecular hydrogen bonds, a decreased volume and in addition a trans to cis isomerization of Pro20. A systematic analysis of the 3-D structural databanks revealed that similar proteins and domains share with AAI the characteristic presence of proline residues, many of which are in a cis backbone conformation. As these proteins fulfil a variety of functional roles and are expressed in very different organisms, we conclude that the structure of the knottin fold, including the propensity of the cis bond, are the result of convergent evolution.

Algorithms↗
PubMed2001

A new algorithm for linear and nonlinear ARMA model parameter estimation using affine geometry.

A linear and nonlinear autoregressive (AR) moving average (MA) (ARMA) identification algorithm is developed for modeling time series data. The new algorithm is based on the concepts of affine geometry in which the salient feature of the algorithm is to remove the linearly dependent ARMA vectors from the pool of candidate ARMA vectors. For noiseless time series data with a priori incorrect model-order selection, computer simulations show that accurate linear and nonlinear ARMA model parameters can be obtained with the new algorithm. Many algorithms, including the fast orthogonal search (FOS) algorithm, are not able to obtain correct parameter estimates in every case, even with noiseless time series data, because their model-order search criteria are suboptimal. For data contaminated with noise, computer simulations show that the new algorithm performs better than the FOS algorithm for MA processes, and similarly to the FOS algorithm for ARMA processes. However, the computational time to obtain the parameter estimates with the new algorithm is faster than with FOS. Application of the new algorithm to experimentally obtained renal blood flow and pressure data show that the new algorithm is reliable in obtaining physiologically understandable transfer function relations between blood pressure and flow signals.

Algorithms↗
PubMed2001

A new algorithm for autoregression moving average model parameter estimation using group method of data handling.

A new algorithm for autoregresive moving average (ARMA) parameter estimation is introduced. The algorithm is based on the group method of data handling (GMDH) first introduced by the Russian cyberneticist, A. G. Ivakhnenko, for solving high-order regression polynomials. The GMDH is heuristic in nature and self-organizes into a model of optimal complexity without any a priori knowledge about the system's inner workings. We modified the GMDH algorithm to solve for ARMA model parameters. Computer simulations have been performed to examine the efficacy of the GMDH and comparison of the GMDH is made to one of the most accurate and one of the most widely used algorithms, the fast orthogonal search (FOS) and the least-squares methods, respectively. The results show that in some cases with noise contamination and incorrect model order assumptions, the GMDH performs better than either the FOS or the least-squares methods in providing only the parameters that are associated with the true model terms.

Algorithms↗
PubMed2001

The ability of an oligomeric human immunodeficiency virus type 1 (HIV-1) envelope antigen to elicit neutralizing antibodies against primary HIV-1 isolates is improved following partial deletion of the second hypervariable region.

Partial deletion of the second hypervariable region from the envelope of the primary-like SF162 virus increases the exposure of certain neutralization epitopes and renders the virus, SF162DeltaV2, highly susceptible to neutralization by clade B and non-clade B human immunodeficiency virus (HIV-positive) sera (L. Stamatatos and C. Cheng-Mayer, J. Virol. 78:7840-7845, 1998). This observation led us to propose that the modified, SF162DeltaV2-derived envelope may elicit higher titers of cross-reactive neutralizing antibodies than the unmodified SF162-derived envelope. To test this hypothesis, we immunized rabbits and rhesus macaques with the gp140 form of these two envelopes. In rabbits, both immunogens elicited similar titers of binding antibodies but the modified immunogen was more effective in eliciting neutralizing antibodies, not only against the SF162DeltaV2 and SF162 viruses but also against several heterologous primary HIV type 1 (HIV-1) isolates. In rhesus macaques both immunogens elicited potent binding antibodies, but again the modified immunogen was more effective in eliciting the generation of neutralizing antibodies against the SF162DeltaV2 and SF162 viruses. Antibodies capable of neutralizing several, but not all, heterologous primary HIV-1 isolates tested were elicited only in macaques immunized with the modified immunogen. The efficiency of neutralization of these heterologous isolates was lower than that recorded against the SF162 isolate. Our results strongly suggest that although soluble oligomeric envelope subunit vaccines may elicit neutralizing antibody responses against heterologous primary HIV-1 isolates, these responses will not be broad and potent unless specific modifications are introduced to increase the exposure of conserved neutralization epitopes.

AIDS Vaccines↗
PubMed2001

Regulation of apolipoprotein secretion by long-chain polyunsaturated fatty acids in newborn swine enterocytes.

Long-chain polyunsaturated fatty acids (LC-PUFA) are important in the development of the immature nervous system, and adding these fatty acids to infant formula has been proposed. To determine the effect of n-3 LC-PUFA on apolipoprotein secretion and lipid synthesis in newborn swine enterocytes, differentiated IPEC-1 cells were incubated for 24 h with docosahexaenoic acid (DHA; 22:6) or eicosapentaenoic acid (EPA; 20:5) complexed with albumin at a fatty acid concentration of 0.8 mM or albumin alone (control) added to the apical medium. Oleic acid (OA; 18:1) was used a control for lipid-labeling studies. Both DHA and EPA reduced apolipoprotein (apo) B secretion by one-half, whereas EPA increased apo A-I secretion. The increased apo A-I secretion occurred primarily in the high-density lipoprotein fraction. These changes in apoprotein secretion were not accompanied by significant changes in synthesis. Modest decreases in apo B mRNA levels were observed for DHA and EPA, whereas there were no changes in apo A-I mRNA abundance. EPA reduced cellular triacylglycerol labeling by one-half, and DHA and EPA decreased cellular phospholipid labeling compared with OA. Labeled triacylglycerol secretion was decreased 75% by EPA, and DHA doubled labeled phospholipid secretion. If present in vivo, these effects should be considered before supplementing infant formula with these fatty acids.

Animals↗
PubMed2001

Morphometric analysis of myelinated axons in the human vagus nerve.

Myelinated axons of the human vagus nerve were analyzed morphometrically on 30 cadavers (16 males and 14 females). The result showed that the transverse area and perimeter of myelinated axons decreased with age, although the total number of their axons did not change.

Adult↗
PubMed2001

Morphometric analysis of the human tibial nerve and the ageing process.

We analysed numbers and sizes of the human tibial nerve branch innervating the soleus muscle. The material was taken from 13 cadavers aged from 67 to 98 years. A linear regression analysis disclosed a significant age-related decrease in the mean number per unit area and the mean transverse area of axons. Such decreases with age may indicate atrophy and loss of motoneurons. Our results could help in understanding the correlation between morphology and function during the ageing process.

Aged↗
PubMed2001

Development of the human gracilis nucleus: a morphometric evaluation.

The development of the human gracilis nucleus was studied on serial sections of the brain of 9 fetuses and neonates at 18-40 weeks of gestation, a two-month-old infant and a 63-year-old adult using a microscope with a drawing tube and an image-analyzing computer system. A morphometric evaluation revealed that the human gracilis nucleus, whose neurons were distinguished from glia from 18 weeks of gestation onward, showed a gradual development in terms of the columnar volume, neuronal size and number, and revealed two kinds of phenomenon: a normal process which occur in the development of the fetus, viz. natural cell death (also called apoptosis), and a phenomenon due to yet unknown causes regarding a discrepancy between the number of neurons and the neuropil index.

Apoptosis↗