Biomedical subjects

Xia Li

Publications and source records attributed to Xia Li.

At least 163 records · Page 9Linked to original sources

PubMed2003

[Identification of the two subtypes of latent autoimmune diabetes in adults by glutamic acid decarboxylase 65 antibody titers].

OBJECTIVE: To compare the clinical characteristics between type 2 diabetes and latent autoimmune diabetes in adults (LADA) and to define the two distinct types of LADA with different glutamic acid decarboxylase antibody (GADA) titers. METHODS: Sera of 750 patients with an initial diagnosis of type 2 diabetes mellitus (T2DM) were screened for GADA with radioimmunoprecipitation assay. The distribution and frequency of different GADA indices were described. Two hundred and ninety five patients were further studied and divided into four groups (T2DM; GADA index < 0.05; index > or = 0.5 and index > or = 0.05 but < 0.5) to compare the age of onset, body mass index, level of major component of adult hemoglobin (HbA1c) and C peptide as well as the rates of hypertension, hyperlipidemia and chronic complications. RESULTS: A total of 64 antibody-positive patients were identified. Compared with T2DM, these patients had younger age of onset, lower C peptide level (fasting C peptide 500 pmol/L vs 414 pmol/L, P < 0.01), lower body mass index (23.2 kg/m(2) vs 21.2 kg/m(2), P < 0.01) and also lower rates of hypertension (48.7% vs 31.7%, P < 0.05) and hyperlipidemia (60.2% vs 38.5%, P < 0.01). However, only the patients with high GADA titer had reduced beta cell function as compared with T2DM and low titer patients. Their diabetic complications were less than those of T2DM. Low GADA titer (index 0.05 - < 0.5) patients were similar to T2DM patients, except that they were prone to ketoacidemia. CONCLUSION: Two clinically distinct types of LADA can be identified by GADA titers. High titer GADA (GADA > or = 0.5) patients have more resemblance to insulin dependent diabetes and can be regarded as LADA-type 1 diabetes, while low titer GADA patients (0.05 - < 0.5) have clinical and metabolic phenotype of type 2 diabetes and can be regarded as LADA-type 2 diabetes.

Adult↗

PubMed2003

Apolipoprotein E genotype in patients with Alzheimer's disease.

OBJECTIVE: To explore the frequency and significance of ApoE gene polymorphisms in patients with sporadic Alzheimer's disease (AD). METHODS: Single nucleotide polymorphisms of the ApoE gene were analyzed in 32 cases of AD and 26 controls, using PCR and gene sequencing. RESULTS: The single nucleotide polymorphism of ApoE gene 462C/G was significantly associated with AD (P < 0.05). CONCLUSIONS: The 462C/G polymorphism might be a specific genotype in Chinese patients with sporadic AD.

Aged↗

PubMed2003

[A primary investigation on disseminated histoplasmosis in Hubei].

OBJECTIVE: To investigate the epidemiologic features of disseminated histoplasmosis (PDH) in Hubei province. METHODS: Bone marrow smears of 12 patients diagnosed as Kala-azer in Hubei province including 4 patients in Jingsan, 2 patients in Shashi and each 1 in Yichang, Jinmen, Zhongxiang, Luotian, Xianning and Guanghua respectively were re-examed under microscope. Peripheral blood and bone marrow smears of several patients were detected. After inoculated the bone marrow, peripheral blood, liver and spleen tissue of patients in MLI, the single colony was trans-inoculated in BHIB, SDA and CMA and incubated at 25 degrees C and 35 degrees C. Bone marrow, peripheral blood and bacterial fluid of yeast-phase Histoplasma capsulatum (H.cap) were injected into the abdominal cavity of Kunming mice and nude mice. When symptoms and signs developed, the spleen tissue was separated, then observed under microscope and cultured. Mycelium-phase and Yeast-phase H.cap were inoculated in urase and gelatin medium, then incubated at 25 degrees C and 35 degrees C. Histoplasmin was injected subcutaneously into patients, and then followed for 48 - 72 hours. Amphotericin B was selected to treat the PDH patients. RESULTS: Moriform cell cluster and sausage-shaped cell were not observed in mononuclear-macrophages in the bone marrow smears from 12 patients. Leishman-Donovan body was found only in one patient. There wasn't kinetoplast in the cellular plasm of spores in 11 patients and no transeptae was found. The reaction of H.cap to urease was positive and H.cap did not liquefy the gelatin. It appeared to be mycelium-phase at 25 degrees C but no penicillus and catenulate conidia was found. The characteristic denticle macroconidia was observed but produced red coloring matter. It also appeared to be yeast-phase at 35 degrees C. Yeast-phase spores were observed under microscope. No sausage-shaped spore and transeptae were identified. H.cap could be acquired in the spleen tissue in Kunming mice and nude mice. Bacterium forms, characteristics under microscope and biochemical reaction of mycelium-phase and yeast-phase H.cap were different from some other kinds of dimorphic fungi such as Penicillium marneffei and Histoplasm duboisii etc. CONCLUSION: There were scattered epidemics of PDH in Hubei province. The detection rate of PDH was higher in the southeast area then in the northwest area. The golden standards of clinic diagnosis were mycological culture and inoculation to animals. Amphotericin B was necommended as the first choice for treatment.

Adolescent↗

PubMed2003

Glutamic acid decarboxylase 65 autoantibody levels discriminate two subtypes of latent autoimmune diabetes in adults.

OBJECTIVE: To compare the clinical characteristics between type 2 diabetes mellitus (T2DM) and latent autoimmune diabetes in adults (LADA) with different titers of glutamic acid decarboxylase autoantibody (GADA) and to define the two distinct subtypes of LADA. METHODS: Sera of 750 patients with an initial diagnosis of T2DM from central south of China were screened for GADA using a radioligand assay. The distribution and frequency of GADA levels were described. Two hundred and ninety-five patients were divided into the T2DM group (n = 233) and the LADA group (n = 62) to compare the age of onset, body mass index, HbA(1c), C-peptide, hypertension, dyslipidemia and chronic diabetic complications. Furthermore, LADA patients with different GADA titers were subdivided to analyze the same indexes as the above. RESULTS: The prevalence of LADA (defined as GADA > or = 0.05, namely GADA positive) was 9.7% in the 750 initially diagnosed type 2 diabetic patients. Compared with T2DM, LADA patients were younger at their ages of onset, had lower C-peptide and body mass index, and also had less cases with hypertension and with dyslipidemia. However, only patients with high titer of GADA had poorer beta cell functions and less diabetic complications compared to T2DM and low GADA titer of LADA patients. Patients with low GADA titer were similar to T2DM patients, except that they were prone to develop ketosis more frequently. CONCLUSIONS: Two clinically distinct subtypes of LADA can be identified by GADA levels in patients initially-diagnosed as type 2 diabetes. Patients with high titer of GADA (GADA > or = 0.5) subsequently develop more insulin dependency, which are classified as LADA-type 1; while those with lower GADA titer (0.05 < or = GADA < 0.5) and having clinical and metabolic phenotypes of type 2 diabetes are classified as LADA-type 2.

Adult↗

PubMed2003

[Latent autoimmune diabetes in adults: an update].

Latent autoimmune diabetes in adults (LADA), presenting with a similar phenotype of type 2 diabetes at early stage, belongs to the slowly progressive subtype of autoimmune type 1 diabetes. LADA differs from classic juvenile-onset type 1 diabetes in which its autoimmune destructive process of islet beta-cells is much slower, so LADA may serve as a human model of autoimmune type 1 diabetes. Although no international standardized criteria for the diagnosis of LADA has been established, it should be noted that LADA has some specific features in clinical characteristics, susceptible genotypes, cellular and humoral immune markers, as well as islet pathology. Presence of islet autoantibodies is necessary for the diagnosis of LADA. Early insulin intervention may preserve residual islet beta-cell function in LADA. The different pathological manifestations of LADA with different autoantibody titers can help throw light on the autoimmune process, laying foundation of prevention or even cure of type 1 diabetes.

Adult↗

PubMed2003

[Metabolic syndrome and latent autoimmune diabetes in adults].

OBJECTIVE: To investigate the prevalence of metabolic syndrome (MS) in latent autoimmune diabetes in adults (LADA) and to study the positivity of glutamic acid decarboxylase autoantibody (GADA) in diabetic patients with MS. METHODS: Sera of 598 patients with an initial diagnosis of type 2 diabetes (T2DM) were screened for GADA with radioligand assay. These patients were divided into LADA and T2DM groups according to the titers of GADA to compare the prevalence of MS; the proportions of LADA in diabetic patients with and without MS were studied. We also compared the clinical characteristics of LADA patients with and without MS. RESULTS: About 23.7% of the LADA patients had MS. In patients with MS, the prevalence of LADA was 10.0%, of which approximately 95% had low GADA titers, that was, belonging to LADA-type 2. Compared with LADA patients with MS, LADA without MS were similar to classical type 1 diabetes and had features of low body weight, tendency to develop ketosis and impaired islet cell function. CONCLUSION: About 23.7% patients with MS are found in LADA patients. The GADA levels in LADA patients with and without MS are significantly different, which may need different therapeutic strategies.

Adolescent↗

PubMed2003

[Effects of different feeding methods on the iodine status of the infants during the weaning period].

OBJECTIVE: To investigate the iodine levels of urine from 1 month old breast-fed infants and the ones of milk and urine from the lactating women, and to observe the effects of different feeding methods (breast-feeding, mixed-feeding, bottle-feeding) on the iodine status of the infants during the weaning period in Beijing. METHODS: From March, 2001 to March, 2002, the iodine levels of urine from 97 breast-fed infants 1 month of age and the ones in milk and urine from lactating women were measured and compared. The infants followed up were divided into 3 groups (breast-fed, mixed and bottle-fed) until 6 months old. Their iodine levels of urine were measured and compared with the ones of 1 month of age. RESULTS: The median value of urine iodine from breast-fed 1 month old infants was 183 micro g/L, suggesting that the infants with breast-fed had good iodine nutritional status. The median value of urine iodine from lactating women was 122 micro g/L, significantly lower than the value of milk iodine, 201 micro g/L (P < 0.001). which suggests that the lactating women were iodine deficient but could provide infants iodine adequately through breast feeding. Compared with 1 month af age, the urine iodine levels of 6 months old infants with breast-feeding increased (P < 0.001), the ones with bottle-feeding decreased significantly (P < 0.001) and the mixed-feeding group did not change (P > 0.05). The differences among 3 groups were significant (P < 0.005), the urine iodine levels of infants of both breast-feeding and mixed-feeding groups were higher than the ones of bottle-feeding. The breast-feeding group was the highest one among three groups. CONCLUSION: The breast-fed infants were nourished with iodine, but the lactating women were iodine deficient. Accompanied the decrease of the amount of breast milk, the iodine levels of infants urine decreased during the weaning period, some bottle-feeding infants were iodine deficient.

Bottle Feeding↗

PubMed2002

Native states of adenylate kinase are two active sub-ensembles.

There are two kinds of conformational forms of adenylate kinase (AK) in equilibrium in solution with different ANS-binding properties. Furthermore, the nature of AP(5)A inhibition suggests also that the native forms of AK for binding with different substrates pre-exist in the absence of substrates. In the present study, a kinetics approach was used to explore the native forms distinguished by ANS-binding properties and by the nature of AP(5)A inhibition. The results revealed that the native forms distinguished by ANS probe are two conformational sub-ensembles. Both sub-ensembles are active and consist of a series of forms, which pre-exist in solution and can bind with different substrates. The K(m) values of N(1) for AMP, ADP and MgATP are larger than that of N(2), indicating that the N(2) sub-ensemble is more specific for binding substrates. This is consistent with the previous observation that the activity of N(2) is about 1.8-fold of that of N(1).

Adenylate Kinase↗

PubMed2002

Mitochondrial recycling of ascorbic acid from dehydroascorbic acid: dependence on the electron transport chain.

Mitochondria can regenerate ascorbic acid from its oxidized forms, which may help to maintain the vitamin both in mitochondria and in the cytoplasm. In this work, we sought to determine the site and mechanism of mitochondrial ascorbate recycling from dehydroascorbic acid. Rat skeletal muscle mitochondria incubated for 3 h at 37 degrees C with 500 microM dehydroascorbic acid and energy substrates maintained ascorbate concentrations more than twice those observed in the absence of substrate. Succinate-dependent mitochondrial reduction of dehydroascorbic acid was blocked by inhibitors of mitochondrial Complexes II and III. Neither cytochrome c nor the outer mitochondrial membrane were necessary for the effect. The ascorbate radical was generated by mitochondria during treatment with dehydroascorbic acid and was abolished by ferricyanide, which does not penetrate the mitochondrial inner membrane. Together, these results show that energy substrate-dependent ascorbate recycling from dehydroascorbic acid involves an externally exposed portion of mitochondrial complex III.

Animals↗

PubMed2002

Uptake, recycling, and antioxidant actions of alpha-lipoic acid in endothelial cells.

Alpha-lipoic acid, which becomes a powerful antioxidant in its reduced form, has been suggested as a dietary supplement to treat diseases associated with excessive oxidant stress. Because the vascular endothelium is dysfunctional in many of these conditions, we studied the uptake, reduction, and antioxidant effects of alpha-lipoic acid in cultured human endothelial cells (EA.hy926). Using a new assay for dihydrolipoic acid, we found that EA.hy926 cells rapidly take up and reduce alpha-lipoic acid to dihydrolipoic acid, most of which is released into the incubation medium. Nonetheless, the cells maintain dihydrolipoic acid following overnight culture, probably by recycling it from alpha-lipoic acid. Acute reduction of alpha-lipoic acid activates the pentose phosphate cycle and consumes nicotinamide adenine dinucleotide phosphate (NADPH). Lysates of EA.hy926 cells reduce alpha-lipoic acid using both NADPH and nicotinamide adenine dinucleotide (NADH) as electron donors, although NADPH-dependent reduction is about twice that due to NADH. NADPH-dependent alpha-lipoic acid reduction is mostly due to thioredoxin reductase. Pre-incubation of cells with alpha-lipoic acid increases their capacity to reduce extracellular ferricyanide, to recycle intracellular dehydroascorbic acid to ascorbate, to decrease reactive oxygen species generated by redox cycling of menadione, and to generate nitric oxide. These results show that alpha-lipoic acid enhances both the antioxidant defenses and the function of endothelial cells.

Antioxidants↗

PubMed2002

[Isolation, cultivation and identification of stem cells from cerebral cortex of mouse embryo].

OBJECTIVE: To isolate, cultivate and identify the neural stem cells from the cortex of embryo mouse in vitro for the further related research. METHODS: Cerebral hemisphere of mouse fetuses were taken out. Suspension of cerebral cells was made. Neural stem cells were identified by immunofluorescent cytochemistry to the primary culture. Neural stem cells were isolated and cultured in special culture medium using single-cell clone culture technique. After the stem cells were stably cultured successively for 20 generations, nestin, glial fibrillary acidic protein, beta-tublin, and galactosidase (Galc) were detected by indirect immunofluorescence cytochemistry. RESULTS: The stem cells isolated from the cerebral hemisphere of mouse embryo with positive expression of nestin could be passaged in vitro for at least 20 generations. Inoculated on the coverglass with poly-1-ornithine and cultured in medium containing serum, the stem cells were induced to differentiate. The cells differentiated from these stem cells showed green fluorescence by GFAP fluorescent staining, red fluorescence by beta-tublin fluorescent staining, or green fluorescence by Galc fluorescent staining. CONCLUSION: The stem cells from cortex of mouse embryo can be successfully isolated and cultured in vitro. The stem cells can be passaged in series and possessed the potential of multi-directional differentiation and express the specific antigens of neuron, astrocytes, and oligodendrocytes. Thus they can be used for further experimental study.

Animals↗

PubMed2002

[Effects of recombinant human bone morphogenic protein-2 and hyaluronic acid on invasion of brain glioma in vivo].

OBJECTIVE: To investigate the effects of recombinant human bone morphogenic protein-2 (rhBMP-2) and hyaluronic acid (HA) on the invasion and metastasis of rat brain glioma in vivo. METHODS: C6 rat glioma cells were transfected with the plasmid vector named pEGFP-N3 which contained an enhanced green fluorescent protein (EGFP) gene. The stable cell clones which expressed EGFP protein were stereotactically injected into the brain parenchyma of SD rats in order to establish a xenotransplanted tumor model. After rhBMP-2 and HA were administered in the xenotransplanted tumor model at different dosages, their effects on glioma invasion and metastasis were observed by pathology, flow cytometry fluoresclnec, and electronmicvoscopy. RESULTS: EGFP-transfected C6 glioma cells gave off green fluorescence in vivo and in vitro. Area with tumor and area without tumor could be easily distinguished by fluorescence microscopy. Even distant micrometastasis and invasion at single-cell level could be detected. 10 microliter rhBMP-2 of the concentration of 5 microgram/ml inhibited C6 tumor invasion, while 10 microliter hyaluronic acid of the concentration of 100 microgram/ml evidently promoted the tumor invasion. CONCLUSION: EGFP-transfected C6 cells can be transplanted into rats' brain so as to establish an excellent experimental animal model in the research on invasion and metastasis of brain glioma in vivo. RhBMP-2 inhibits tumor invasion, while HA evidently promotes its invasion.

Animals↗

PubMed2002

Genetic, physical, and comparative map of the subtelomeric region of mouse Chromosome 4.

The subtelomeric region of mouse chromosome (Chr) 4 harbors loci with effects on behavior, development, and disease susceptibility. Regions near the telomeres are more difficult to map and characterize than other areas because of the unique features of subtelomeric DNA. As a result of these problems, the available mapping information for this part of mouse Chr 4 was insufficient to pursue candidate gene evaluation. Therefore, we sought to characterize the area in greater detail by creating a comprehensive genetic, physical, and comparative map. We constructed a genetic map that contained 30 markers and covered 13.3 cM; then we created a 1.2-Mb sequence-ready BAC contig, representing a 5.1-cM area, and sequenced a 246-kb mouse BAC from this contig. The resulting sequence, as well as approximately 40 kb of previously deposited genomic sequence, yielded a total of 284 kb of sequence, which contained over 20 putative genes. These putative genes were confirmed by matching ESTs or cDNA in the public databases to the genomic sequence and/or by direct sequencing of cDNA. Comparative genome sequence analysis demonstrated conserved synteny between the mouse and the human genomes (1p36.3). DNA from two strains of mice (C57BL/6ByJ and 129P3/J) was sequenced to detect single nucleotide polymorphisms (SNPs). The frequency of SNPs in this region was more than threefold higher than the genome-wide average for comparable mouse strains (129/Sv and C57BL/6J). The resulting SNP map, in conjunction with the sequence annotation and with physical and genetic maps, provides a detailed description of this gene-rich region. These data will facilitate genetic and comparative mapping studies and identification of a large number of novel candidate genes for the trait loci mapped to this region.

Animals↗

PubMed2002

Catalase-dependent measurement of H2O2 in intact mitochondria.

Mitochondria generate potentially damaging amounts of superoxide and H2O2 during oxidative metabolism. Although many assays are available to measure mitochondrial H2O2 generation, most detect H2O2 that has escaped the organelle. To measure H2O2 within mitochondria that contain catalase, we have developed an assay based on the ability of H2O2 to inhibit catalase in the presence of 3-amino-1,2,4-triazole. The assay is simple to perform, does not require expensive instrumentation, and is specific for H2O2. Results from this assay show that H2O2 generation in rat heart mitochondria reflects the activity of the electron transport chain. Further, liver mitochondria prepared from selenium-deficient rats have increased succinate-stimulated rates of H2O2 generation. This indicates that mitochondrial selenoenzymes are important for H2O2 removal. It also demonstrates the utility of this assay in measuring H2O2 release from mitochondria that do not contain catalase. The assay should be useful for study of both superoxide-dependent H2O2 generation in situ, and the role of endogenous mitochondrial catalase in H2O2 removal.

Journal Article↗

PubMed2002

Photosynthetic characteristics and tolerance to photo-oxidation of transgenic rice expressing C(4) photosynthesis enzymes.

The photosynthetic characteristics of four transgenic rice lines over-expressing rice NADP-malic enzyme (ME), and maize phosphoenolpyruvate carboxylase (PC), pyruvate,orthophosphate dikinase (PK), and PC+PK (CK) were investigated using outdoor-grown plants. Relative to untransformed wild-type (WT) rice, PC transgenic rice exhibited high PC activity (25-fold increase) and enhanced activity of carbonic anhydrase (more than two-fold increase), while the activity of ribulose-bisphosphate carboxylase/oxygenase (Rubisco) and its kinetic property were not significantly altered. The PC transgenic plants also showed a higher light intensity for saturation of photosynthesis, higher photosynthetic CO(2) uptake rate and carboxylation efficiency, and slightly reduced CO(2) compensation point. In addition, chlorophyll a fluorescence analysis indicates that PC transgenic plants are more tolerant to photo-oxidative stress, due to a higher capacity to quench excess light energy via photochemical and non-photochemical means. Furthermore, PC and CK transgenic rice produced 22-24% more grains than WT plants. Taken together, these results suggest that expression of maize C(4) photosynthesis enzymes in rice, a C(3) plant, can improve its photosynthetic capacity with enhanced tolerance to photo-oxidation.

Journal Article↗

PubMed2002

Experiment and observation on invasion of brain glioma in vivo.

Research on invasion and metastasis of glioma in vivo was performed by implanting C6 glioma cells transfected with enhanced green fluorescent protein (EGFP) gene into the brain of SD rats. Firstly, C6 glioma cells were transfected with a plasmid vector (pEGFP-N3) containing the EGFP gene. Stable EGFP-expressing clones were isolated and examination for these cells by flow cytometry and electron microscope was done. Secondly, EGFP-expressing cells were stereotactically injected into the brain parenchyma of SD rats to establish xenotransplanted tumor. Four weeks later rats were killed and continuous brain sections were examined using fluorescence microscopy after adjacent sections were examined by immunohistochemistry or routine hematoxylin and eosin staining for the visualization and detection of tumor cell invasion. Xenotransplanted tumor was primarily cultured to determine the storage of EGFP gene in vivo. The results showed that EGFP-transfected C6 glioma cells maintained stable high-level EGFP expression in the central nervous system during their growth in vivo. EGFP fluorescence clearly demarcated the primary tumor margin and readily allowed for the visualization of distant micrometastasis and invasion on the single-cell level. Small locally invasive foci, including those immediately adjacent to the leading invasive edge of the tumor, were virtually undetectable by routine hematoxylin and eosin staining and immunohistochemistry. These results suggested that EGFP-transfected C6 cells can be visualized by fluorescence microscopy after intracranial implantation. This model is an excellent experimental animal model in research on invasion and metastasis of brain glioma in vivo.

Animals↗

PubMed2002

Voluntary ethanol consumption by mice: genome-wide analysis of quantitative trait loci and their interactions in a C57BL/6ByJ x 129P3/J F2 intercross.

Consumption of ethanol solutions by rodents in two-bottle choice tests is a model to study human alcohol intake. Mice of the C57BL/6ByJ strain have higher ethanol preferences and intakes than do mice of the 129P3/J strain. F2 hybrids between these two strains were phenotyped using two-bottle tests involving a choice between water and either 3% or 10% ethanol. High ethanol preferences and intakes of the B6 mice were inherited as additive or dominant traits in the F2 generation. A genome screen using these F2 mice identified three significant linkages. Two loci, on distal chromosome 4 (Ap3q) and proximal chromosome 7 (Ap7q), strongly affected 10% ethanol intake and weakly affected 3% ethanol intake. A male-specific locus on proximal chromosome 8 (Ap8q) affected 3% ethanol preference, but not indexes of 10% ethanol consumption. In addition, six suggestive linkages (on chromosomes 2, 9, 12, 13, 17, and 18) affecting indexes of 3% and/or 10% ethanol consumption were detected. The loci with significant and suggestive linkages accounted for 35-44% of the genetic variation in ethanol consumption phenotypes. No additive-by-additive epistatic interactions were detected for the primary loci with significant and suggestive linkages. However, there were a few modifiers of the primary linkages and a number of interactions among unlinked loci. This demonstrates a significant role of the genetic background in the variation of ethanol consumption.

Alcohol Drinking↗

PubMed2002

Human immunodeficiency virus type 1 enters brain microvascular endothelia by macropinocytosis dependent on lipid rafts and the mitogen-activated protein kinase signaling pathway.

Brain microvascular endothelial cells (BMVECs) present an incomplete barrier to human immunodeficiency virus type 1 (HIV-1) neuroinvasion. In order to clarify the mechanisms of HIV-1 invasion, we have examined HIV-1 uptake and transcellular penetration in an in vitro BMVEC model. No evidence of productive infection was observed by luciferase, PCR, and reverse transcriptase assays. Approximately 1% of viral RNA and 1% of infectious virus penetrated the BMVEC barrier without disruption of tight junctions. The virus upregulated ICAM-1 on plasma membranes and in cytoplasmic vesiculotubular structures. HIV-1 virions were entangled by microvilli and were taken into cytoplasmic vesicles through surface invaginations without fusion of the virus envelope with the plasma membrane. Subsequently, the cytoplasmic vesicles fused with lysosomes, the virions were lysed, and the vesicles diminished in size. Upon cell entry, HIV-1 colocalized with cholera toxin B, which targets lipid raft-associated GM1 ganglioside. Cholesterol-extracting agents, cyclodextrin and nystatin, and polyanion heparin significantly inhibited virus entry. Anti-CD4 had no effect and the chemokine AOP-RANTES had only a slight inhibitory effect on virus entry. HIV-1 activated the mitogen-activated protein kinase (MAPK) pathway, and inhibition of MAPK/Erk kinase inhibited virus entry. Entry was also blocked by dimethylamiloride, indicating that HIV-1 enters endothelial cells by macropinocytosis. Therefore, HIV-1 penetrates BMVECs in ICAM-1-lined macropinosomes by a mechanism involving lipid rafts, MAPK signaling, and glycosylaminoglycans, while CD4 and chemokine receptors play limited roles in this process.

Blood-Brain Barrier↗