[Effect and mechanism of human adipose-derived stem cell exosomes on diabetic peripheral neuropathy]

Objective: To investigate the changes of artemin protein expression in diabetic peripheral neuropathy (DPN) and to explore the regulatory effect of human adipose-derived stem cell (ADSC) exosomes on the change of artemin protein expression. Methods: This research was a prospective observational clinical research combined with experimental research. Thirteen DPN patients (9 males and 4 females, aged 32 to 68 years) who were admitted to the First Affiliated Hospital of Air Force Medical University (hereinafter referred to as our hospital) from May 2022 to October 2023 and met the inclusion criteria were selected as DPN group, and 5 non-diabetes patients (4 males and 1 female, aged 29 to 61 years) who were admitted to our hospital in the same period of time and met the inclusion criteria were selected as control group. The toe nerve or sural nerve tissue in the abandoned tissue after debridement or amputation of patients in the two groups was collected. The pathological changes of nerve tissue were observed after hematoxylin-eosin staining; the protein expressions of S100β and artemin in nerve tissue were observed after immunofluorescence staining, and the artemin protein expression was quantified; the protein and mRNA expressions of artemin were detected by Western blotting and real-time fluorescent quantitative reverse transcription polymerase chain reaction, respectively (the sample number in DPN group and control group was 13 and 5, respectively). Twelve male C57BL/6 mice aged 3 to 5 days were collected to isolate Schwann cells, and the cells were divided into conventional culture group cultured routinely, high glucose alone group (cultured with high concentration of glucose solution only), and high glucose+exosome group (cultured with high concentration of glucose solution and extracted human ADSC exosomes). After 24 hours of culture, the cell proliferation activity was detected by cell counting kit 8 (n=6). After 48 hours of culture, the protein expression of artemin was detected by Western blotting (n=3). Results: Compared with those in control group, the neural supporting cells decreased and the inflammatory cells increased in the nerve tissue of patients in DPN group, showing typical manifestations of nerve injury. Immunofluorescence staining showed that compared with those in control group, the nuclei was more, and the protein expression of S100β was lower in nerve tissue of patients in DPN group. The protein expression of artemin in nerve tissue of patients in DPN group was 71±31, which was significantly lower than 1 729±62 in control group (t=76.92, P<0.05). Western blotting detection showed that the protein expression of artemin in nerve tissue of patients in DPN group was 0.74±0.08, which was significantly lower than 0.97±0.06 in control group (t=5.49, P<0.05). The artemin mRNA expression in nerve tissue of patients in DPN group was significantly lower than that in control group (t=7.65, P<0.05). After 24 hours of culture, compared with that in conventional culture group, the proliferation activities of Schwann cells in high glucose alone group and high glucose+exosome group were significantly decreased (P<0.05); compared with that in high glucose alone group, the proliferation activity of Schwann cells in high glucose+exosome group was significantly increased (P<0.05). After 48 hours of culture, compared with those in conventional culture group, the protein expressions of artemin of Schwann cells in high glucose alone group and high glucose+exosome group were significantly decreased (P<0.05); compared with that in high glucose alone group, the protein expression of artemin of Schwann cells in high glucose+exosome group was significantly increased (P<0.05). Conclusions: The protein expression of artemin in nerve tissue of DPN patients is lower than that in normal nerve tissue, which may be related to the reduction of proliferation activity of Schwann cells by high glucose. Human ADSC exosomes may improve the proliferation activity of Schwann cells by increasing artemin protein expression, thereby delaying the progression of DPN.

[Research advances on the role of Schwann cells in diabetic peripheral neuropathy]

Diabetic peripheral neuropathy (DPN) is one of the common chronic complications of diabetes, resulting in neuropathy of spinal nerve, cranial nerve, and vegetative nerve. Diabetic distal symmetric multiple neuropathy is the most representative lesion of DPN, including symptoms of bilateral limbs pain, numbness, and paresthesia, etc. DPN is one of the main reasons causing diabetic foot ulcer (DFU). Schwann cells (SCs) are the primary glia cells of the peripheral nervous system, which play very important role in repairing after nerve injury. As the target cells of chronic hyperglycemia, SCs' functions, including the formation of myelin sheath, the secretion of neurotrophic factors, energy supplying for the axon, and the guidance of axon regeneration, etc., are damaged under the action of high glucose. The destroyed functions of SCs can inhibit the repair of damaged nerves and accelerate the progress of DPN. Therefore, if the damage of high glucose to SCs can be effectively reduced, it will provide a new way for the treatment of DPN and DFU and reduce the morbidity of DFU. This review focuses on the function of SCs and its relationship with DPN.

[Effects of the anterolateral thigh chimeric perforator flaps in repairing complex wounds of foot and ankle]

Objective: To investigate the effects of anterolateral thigh chimeric perforator flap in repairing complex wounds of foot and ankle. Methods: A retrospective observational study was conducted. From May 2018 to June 2022, 23 patients who met the inclusion criteria were admitted to the First Affiliated Hospital of Air Force Medical University to repair complex wounds of foot and ankle with anterolateral thigh chimeric perforator flaps, including 15 males and 8 females, aged from 20 to 66 years. The wounds were all accompanied by bone exposure and defects, and were complicated with varying degrees of infection. All patients underwent debridement and continuous vacuum sealing drainage treatment for 1 week in stage Ⅰ, with the skin and soft tissue defect area after debridement being 10 cm×5 cm to 22 cm×7 cm. In stage Ⅱ, the anterolateral thigh chimeric perforator flap was used to cover the defective wound, of which the muscle flap was used to fill the deep invalid cavity of the ankle joint or cover bone and internal fixation exposures, and the skin flap was used to cover the superficial wound, with the area of the skin flap ranging from 11 cm×6 cm to 23 cm×8 cm, and the area of the muscle flap ranging from 4.0 cm×2.5 cm to 8.0 cm×5.0 cm. The survival of the flap was observed after operation. During follow-up, the color, texture, appearance, and complications of the flap were observed, the function of ankle joint and its range of dorsiflexion motion and plantar flexion motion were measured, and the scar hyperplasia and muscular hernia in donor area were observed. Results: Ecchymosis and epidermal necrosis occurred at the tip of the flap in 1 patient on 5 days after operation and healed after dressing change for 1 week; the other flaps of patients survived successfully. After 6 to 40 months of follow-up, the color, texture, and shape of flaps were good, but 1 patient was not satisfied with the shape of the flap because of flap swelling; the ankle joint movement was basically normal, the dorsiflexion motion was 15-30°, and the plantar flexion motion was 20-45°; the scar hyperplasia in the donor area of the flap was not obvious, and no muscular hernia occurred. Conclusions: The anterolateral thigh chimeric perforator flap can effectively fill the deep invalid cavity of ankle joint and cover the superficial wound at the same time, with minimal damage to the donor site. So it is an ideal flap for repairing the complex wounds of foot and ankle.

[A prospective randomized controlled study of antibiotic bone cement in the treatment of diabetic foot ulcer]

Objective: To investigate the clinical effects and related mechanism of antibiotic bone cement in treating diabetic foot ulcer (DFU). Methods: A prospective randomized controlled study was conducted. From August 2020 to August 2022, 24 patients with DFU who met the inclusion criteria were admitted to the First Affiliated Hospital of Air Force Medical University. According to the block randomization, the patients were divided into 2 groups, with 12 patients in each group. In antibiotic bone cement group, there were 7 male and 5 female patients, aged (64±8) years, with the ulcer area of (41±21) cm2. In silver sulfadiazine group, there were 8 male and 4 female patients, aged (62±8) years, with the ulcer area of (38±19) cm2. Under the condition of ensuring the patency of at least one main inferior genicular artery in each patient, the continuous vacuum sealing drainage was performed for 3-5 days after thorough debridement. Thereafter, the wounds in antibiotic bone cement group were treated with gentamicin-laden bone cement, and the wounds in silver sulfadiazine group were treated with silver sulfadiazine cream for dressing change. After 3 weeks of dressing change, the wound was covered with split-thickness skin graft from the lateral thigh on the affected side. Before debridement and after 3 weeks of dressing change, the blood flow intensities of wound tissue and normal skin tissue in foot were measured using laser Doppler flowmeter, and then, the percentage of relative blood flow intensity of wound and the change rate of blood flow intensity were calculated. After 3 weeks of dressing change, the wound margin tissue was taken, the number of CD31-positive neovascular and the vascular morphology were observed and detected by immunohistochemical staining, the morphology of blood vessels surrounded by CD31 and α-smooth muscle actin (α-SMA) double-positive cells was observed by immunofluorescence staining, the cell proliferation activity was evaluated by immunofluorescence staining (denoted as the ratio of Ki67 positive cells), and the protein expression of vascular endothelial growth factor receptor 2 (VEGFR2) was detected by Western blotting. The skin graft survival was observed 3-5 days after skin grafting, and the wound healing time was recorded. Data were statistically analyzed with independent sample t test and Fisher's exact probability test. Results: The percentages of relative blood flow intensity of wounds of patients before debridement were similar between the two groups (P>0.05). After 3 weeks of dressing change, the percentage of relative blood flow intensity of wounds and the change rate of blood flow intensity of patients in antibiotic bone cement group were (44.7±2.0)% and (129±12)%, respectively, which were significantly higher than (28.3±1.2)% and (41±8)% in silver sulfadiazine group (with t values of 24.15 and 20.97, respectively, P<0.05). After 3 weeks of dressing change, compared with those in silver sulfadiazine group, the number of CD31-positive neovascular in the wound margin tissue of patients in antibiotic bone cement group was significantly increased (t=33.81, P<0.05) with larger diameter and more regular arrangement, the vascular wall continuity surrounded by CD31 and α-SMA double-positive cells was better, and the ratio of Ki67 positive cells and protein expression of VEGFR2 were significantly increased (with t values of 40.97 and 47.38, respectively, P<0.05). On post skin grafting day 3-5, all the patients in antibiotic bone cement group and 8 patients in silver sulfadiazine group had good skin graft survival, while 4 patients in silver sulfadiazine group showed spotted/patchy skin graft necrosis, which were cured after corresponding treatment. The wound healing time of patients in antibiotic bone cement group was (47.1±2.9) d, which was significantly shorter than (58.8±2.3) d in silver sulfadiazine group (t=10.86, P<0.05). Conclusions: Compared with silver sulfadiazine, clinical application of antibiotic bone cement for treating DFU has the characteristics of accelerating wound healing and better reconstruction of local blood flow, which may be closely related to the fact that antibiotic bone cement promoted the local angiogenesis effectively in the wound through enhancing the expression of VEGFR2.

MicroRNA-363-3p/p21(Cip1/Waf1) axis is regulated by HIF-2α in mediating stemness of melanoma cells

Melanoma is a malignant tumor. The acquisition of stemness of melanoma cells aggravates the malignant transformation, which can be regulated by microRNAs (miRNAs, miR). MiR-363-3p is a key tumor-related miRNA, but its role in stemness and melanoma cells is still unknown. Presently, miR-363-3p, induced by hypoxia inducible factor (HIF)-2α, played a positive role in the stemness of melanoma cells. The levels of miR-363-3p and HIF-2α were upregulated in melanoma cell lines. Overexpression of HIF-2α significantly increased the levels of miR-363-3p. However, both HIF-2α knockdown and miR-363-3p inhibition inhibited the levels of the stemness markers (CD133, CD271, Jarid1B, and Nanog). Furthermore, the levels of miR-363-3p and HIF-2α were upregulated in fluorescence activated cell sorting (FACS)-sorted CD271high/+ cells. Whereas miR-363-3p depletion reduced the proportion and the spheroidization of the CD271high/+ cells, decreased the levels of CD133, CD271, Jarid1B and Nanog with restrained proliferative activity of CD271high/+ cells. Additionally, miR-363-3p was confirmed a key downstream of HIF-2α. Intriguingly, cyclin-dependent kinase inhibitor 1A [CDKN1A, p21(Cip1/Waf1)], a key inhibitor of S-phase DNA synthesis and cell cycle progression, was confirmed a target gene of miR-363-3p by luciferase reporter gene assay. The protein levels of CD133, CD271, Jarid1B and Nanog were upregulated with enhanced proliferative activity of CD271high/+ cells by inhibition of p21 in melanoma cells. In conclusion, miR-363-3p is induced by HIF-2α to promote the stemness of melanoma cells via inhibiting p21. The present study provides novel insights that HIF-2α/miR-363-3p/p21 signaling may be a potential target of research and therapy of melanoma.

Stillinger-Weber potential for elastic and fracture properties in graphene and carbon nanotubes

This paper presents a new framework for determining the Stillinger-Weber (SW) potential parameters for modeling fracture in graphene and carbon nanotubes. In addition to fitting the equilibrium material properties, the approach allows fitting the potential to the forcing behavior as well as the mechanical strength of the solid, without requiring ad hoc modification of the nearest-neighbor interactions for avoiding artificial stiffening of the lattice at larger deformation. Consistent with the first-principles results, the potential shows the Young's modulus of graphene to be isotropic under symmetry-preserving and symmetry-breaking deformation conditions. It also shows the Young's modulus of carbon nanotubes to be diameter-dependent under symmetry-breaking loading conditions. The potential addresses the key deficiency of existing empirical potentials in reproducing experimentally observed glass-like brittle fracture in graphene and carbon nanotubes. In simulating the entire deformation process leading to fracture, the SW-potential costs several factors less computational time compared to the state-of-the-art interatomic potentials that enables exploration of the fracture processes in large atomistic systems which are inaccessible otherwise.

Adaptive semantic tag mining from heterogeneous clinical research texts

OBJECTIVES

To develop an adaptive approach to mine frequent semantic tags (FSTs) from heterogeneous clinical research texts.

METHODS

We develop a "plug-n-play" framework that integrates replaceable unsupervised kernel algorithms with formatting, functional, and utility wrappers for FST mining. Temporal information identification and semantic equivalence detection were two example functional wrappers. We first compared this approach's recall and efficiency for mining FSTs from ClinicalTrials.gov to that of a recently published tag-mining algorithm. Then we assessed this approach's adaptability to two other types of clinical research texts: clinical data requests and clinical trial protocols, by comparing the prevalence trends of FSTs across three texts.

RESULTS

Our approach increased the average recall and speed by 12.8% and 47.02% respectively upon the baseline when mining FSTs from ClinicalTrials.gov, and maintained an overlap in relevant FSTs with the base- line ranging between 76.9% and 100% for varying FST frequency thresholds. The FSTs saturated when the data size reached 200 documents. Consistent trends in the prevalence of FST were observed across the three texts as the data size or frequency threshold changed.

CONCLUSIONS

This paper contributes an adaptive tag-mining framework that is scalable and adaptable without sacrificing its recall. This component-based architectural design can be potentially generalizable to improve the adaptability of other clinical text mining methods.

Synergy between Kaposi's sarcoma-associated herpesvirus (KSHV) vIL-6 and HIV-1 Nef protein in promotion of angiogenesis and oncogenesis: role of the AKT signaling pathway

Kaposi's sarcoma-associated herpesvirus (KSHV) is the cause of Kaposi's sarcoma (KS), which is the most common AIDS-associated malignancy. KS is characterized by neovascularization and spindle cell proliferation. The interaction between HIV-1 and KSHV has a central role in promoting the aggressive manifestations of KS in AIDS patients; however, the pathogenesis underlying AIDS-related KS (AIDS-KS) remains unknown. Herein, we examined the potential of HIV-1 negative factor (Nef) to impact KSHV viral interleukin-6 (vIL-6)-induced angiogenesis and tumorigenesis. In vitro experiments showed that exogenous Nef penetrated vIL-6-expressing endothelial cells. Both internalized and ectopic expression of Nef in endothelial cells and fibroblasts synergized with vIL-6 to promote vascular tube formation and cell proliferation. Using a chicken chorioallantoic membrane (CAM) model, we demonstrated that Nef synergistically promotes vIL-6-induced angiogenesis and tumorigenesis. Animal experiments further showed that Nef facilitates vIL-6-induced angiogenesis and tumor formation in athymic nu/nu mice. Mechanistic studies indicated that Nef synergizes with vIL-6 to enhance angiogenesis and tumorigenesis by activating the AKT pathway in the CAM model, as well as nude mice. LY294002, a specific inhibitor of phosphatidylinositol-3-kinase (PI3K), significantly impaired the ability of Nef to promote vIL-6-induced tumorigenesis in an allograft model of nude mice. Our data provide first-line evidence that Nef may contribute to the pathogenesis underlying AIDS-KS in synergy with vIL-6. These novel findings also suggest that targeting the PI3K/AKT signal may be a potentially effective therapeutic approach in AIDS-KS patients.

Changes in water and beverage intake and long-term weight changes: results from three prospective cohort studies

OBJECTIVE

To examine the long-term relationship between changes in water and beverage intake and weight change.

SUBJECTS

Prospective cohort studies of 50013 women aged 40-64 years in the Nurses' Health Study (NHS, 1986-2006), 52987 women aged 27-44 years in the NHS II (1991-2007) and 21988 men aged 40-64 years in the Health Professionals Follow-up Study (1986-2006) without obesity and chronic diseases at baseline.

MEASURES

We assessed the association of weight change within each 4-year interval, with changes in beverage intakes and other lifestyle behaviors during the same period. Multivariate linear regression with robust variance and accounting for within-person repeated measures were used to evaluate the association. Results across the three cohorts were pooled by an inverse-variance-weighted meta-analysis.

RESULTS

Participants gained an average of 1.45 kg (5th to 95th percentile: -1.87 to 5.46) within each 4-year period. After controlling for age, baseline body mass index and changes in other lifestyle behaviors (diet, smoking habits, exercise, alcohol, sleep duration, TV watching), each 1 cup per day increment of water intake was inversely associated with weight gain within each 4-year period (-0.13 kg; 95% confidence interval (CI): -0.17 to -0.08). The associations for other beverages were: sugar-sweetened beverages (SSBs) (0.36 kg; 95% CI: 0.24-0.48), fruit juice (0.22 kg; 95% CI: 0.15-0.28), coffee (-0.14 kg; 95% CI: -0.19 to -0.09), tea (-0.03 kg; 95% CI: -0.05 to -0.01), diet beverages (-0.10 kg; 95% CI: -0.14 to -0.06), low-fat milk (0.02 kg; 95% CI: -0.04 to 0.09) and whole milk (0.02 kg; 95% CI: -0.06 to 0.10). We estimated that replacement of 1 serving per day of SSBs by 1 cup per day of water was associated with 0.49 kg (95% CI: 0.32-0.65) less weight gain over each 4-year period, and the replacement estimate of fruit juices by water was 0.35 kg (95% CI: 0.23-0.46). Substitution of SSBs or fruit juices by other beverages (coffee, tea, diet beverages, low-fat and whole milk) were all significantly and inversely associated with weight gain.

CONCLUSION

Our results suggest that increasing water intake in place of SSBs or fruit juices is associated with lower long-term weight gain.

Granulation of anaerobic sludge in the sulfate-reducing up-flow sludge bed (SRUSB) of SANI(®) process

This study reports on anaerobic sludge granulation in a laboratory-scale sulfate-reducing up-flow sludge bed (SRUSB) in a novel sulfate reduction, autotrophic denitrification and nitrification integrated (SANI(®)) process for treatment of saline sewage. Granulation occurred in 30 d and reached full development in 90 d. The sulfate-reducing granules grew up to around 1 mm after 90 d with 21 mL/g SVI5 (sludge volume index measured after 5 min) and the biomass concentration reached 29 g/L after 4 months' operation. The reactor removed 89% chemical oxygen demand (COD) and reduced 75% sulfate within 1 h of hydraulic retention time, under a COD loading rate of up to 6.4 kg COD/(m(3) · d).

Phosphorus release and uptake during start-up of a covered and non-aerated sequencing batch reactor with separate feeding of VFA and sulfate

This study explored a sulfur cycle-associated biological phosphorus (P) removal process in a covered and non-aerated sequencing batch reactor (SBR) fed with volatile fatty acid (VFA) and sulfate separately. During the 60-day start-up, both phosphate release and uptake rates increased, while poly-phosphate cyclically increased and decreased accordingly. The P-release and P-uptake rates were associated with VFA uptake and sulfate reduction. The average ratio of potassium to phosphate during the P-uptake and P-release was also determined to be 0.29-0.31 mol K/mol P, which is close to a reported value (0.33) for biological phosphorus removal. All this evidence confirmed there was biological P removal in this reactor, in which metabolism could be different from conventional biological P removal.

The support of matrix accumulation and the promotion of sheep articular cartilage defects repair in vivo by chitosan hydrogels

OBJECTIVE

Chitosan has been widely used as an injectable scaffold in cartilage tissue engineering due to its characteristic biocompatibility and biodegradability. In this study, chitosan was used in its hydrogel form as a scaffold for chondrocytes that act to reconstruct tissue-engineered cartilage and repair articular cartilage defects in the sheep model. This study aims to find a novel way to apply chitosan in cartilage tissue engineering.

METHODS

Temperature-responsive chitosan hydrogels were prepared by combining chitosan, beta-sodium glycerophosphate (GP) and hydroxyethyl cellulose (HEC). Tissue-engineered cartilage reconstructions were made in vitro by mixing sheep chondrocytes with a chitosan hydrogel. Cell survival and matrix accumulation were analyzed after 3 weeks in culture. To collect data for in vivo repair, reconstructions cultured for 1 day were transplanted to the freshly prepared defects of the articular cartilage of sheep. Then at both 12 and 24 weeks after transplantation, the grafts were extracted and analyzed histologically and immunohistochemically.

RESULTS

The results showed that the chondrocytes in the reconstructed cartilage survived and retained their ability to secrete matrix when cultured in vitro. Transplanted in vivo, the reconstructions repaired cartilage defects completely within 24 weeks. The implantation of chitosan hydrogels without chondrocytes also helps to repair cartilage defects.

CONCLUSIONS

The chitosan-based hydrogel could support matrix accumulation of chondrocytes and could repair sheep cartilage defects in 24 weeks. This study showcased the success of a new technique in its ability to repair articular cartilage defects.

Protective immune responses elicited in mice by immunization with formulations of poly(lactide-co-glycolide) microparticles

Parenteral administration of microparticle encapsulated DNA elicits immune responses to the encoded antigens. Experiments were performed to test whether the addition of certain lipophilic agents to such formulations enhanced the activity of a beta-galactosidase (beta-gal) DNA vaccine. Addition of either taurocholic acid (TA) or monomethoxy polyethylene-glycol-distearoylphosphatidylehanolamine (PEG-DSPE) increased the efficiency of DNA encapsulation. Immunization of mice with encapsulated DNA formulations containing either compound significantly increased the number of antibody positive responders over that achieved with non-lipid containing particles. Moreover, responding animals demonstrated trends towards higher antibody titers and increased T cell responses. Tumor protection against the CT26.CL25 tumor cell line was demonstrated with lipid and non-lipid containing formulations. These results are the first demonstration of protection obtained by parenteral administration of PLG encapsulated DNA vaccines.

Bullous amyloidosis: the mechanism of blister formation revealed by electron microscopy

BACKGROUND

Few electron microscopic studies of blister lesions in bullous amyloidosis have been reported, and the mechanism of blister formation remains to be elucidated. This study was designed to examine the nature of bullous amyloidosis ultrastructurally, and clarify the pathogenesis of blister formation.

METHODS

We examined a 47-year-old woman with IgD-lambda type myeloma, suffering from bullous lesions on her hands and feet caused by trauma or rubbing. Light and electron microscopic studies were performed.

RESULT

Ultrastructurally, amyloid deposits aggregated under the lamina densa. Keratinocyte protrusions penetrated the dermis through the gap in the lamina densa and enfolded amyloid deposits. Amyloid globules were found in enlarged intercellular spaces of keratinocytes. Desmosomes were sparsely distributed in some areas of the epidermis.

CONCLUSION

These results indicate that keratinocytes enfold the amyloid globules and take them in the intercellular space of epidermis, and that the breakdown of the lamina densa and widening of the intercellular space between keratinocytes induce skin fragility. Trauma or rubbing of her hands and feet appears to act as the localized precipitating factor of blister formation in bullous amyloidosis.

Biological potency of microsphere encapsulated plasmid DNA

We evaluated the utility of three in vitro methods to monitor the biological potency of PLGA encapsulated DNA. For each assay we also determined whether the biological activity was influenced by the structural profile of DNA isomers. Collectively, the results indicate that all three methods can be used to evaluate the biological activity of DNA extracted from PLGA microspheres, but they are differentially sensitive to the structural changes of plasmid DNA that can occur during microencapsulation and microsphere storage. More specifically, mammalian cell transfection followed by an enzyme assay affords an accurate determination of DNA potency over time and is less influenced by DNA isoform than bacterial transformation. Cell-free transcription/translation systems can also be utilized, and the results of this assay are influenced by DNA isoform. Finally, bacterial transformation was found to be more sensitive to DNA isoform than the other assay methods.

Heat-shock protein 70 can replace viral protein R of HIV-1 during nuclear import of the viral preintegration complex

Heat-shock proteins (Hsp's) are a family of molecular chaperones that contribute to protection from environmental stress. In this report, we demonstrate that a member of this family, Hsp70, facilitates nuclear import of HIV-1 preintegration complexes (PICs). The mechanism of this activity appears to be similar to the one used by Vpr, an HIV-1 protein regulating viral nuclear import and replication in macrophages. Indeed Hsp70 stimulated binding of HIV-1 matrix antigen to GST-karyopherin alpha fusion protein and rescued nuclear import of a Vpr-defective HIV-1 strain in vitro. Binding studies with truncated forms of GST-karyopherin alpha demonstrated that both Vpr and Hsp70 bind to a region in the amino-terminal part of the karyopherin alpha molecule. This region appears to be distinct from the binding sites for two other karyopherin alpha cargoes, basic-type NLS-containing proteins and transcription factor STAT-1. Vpr competed with Hsp70 for binding to karyopherin alpha. These results suggest the presence of a novel regulatory site on karyopherin alpha which is used by Hsp70 and Vpr to stimulate interaction between the HIV-1 PIC and karyopherin alpha and thus promote viral nuclear import.

Effects of cigarette smoke extract on E-cadherin expression in cultured airway epithelial cells

To investigate whether the change of E-cadherin (ECD) expression plays a role in the injury and repair of airway epithelial cells (AEC) caused by smoking, porcine AECs were cultured by using an enzyme-dispersed method. After exposure of the AECs to cigarette smoke extract (CSE), the ECD expression in the cells was detected by using immunocytochemistry and in situ hybridization. The results showed that ECD was distributed on the plasma membrane at the cell junctions of AECs. After exposure to 20% CSE, the membranous ECD expression was decreased, the cytoplasmic ECD expression was increased (P < 0.01) as the exposure time went on. But the content of ECD mRNA in the AECs did not chang. It suggests that the change of ECD expression is regulated at the posttranslational level and plays a role in the injury and repair of AEC caused by smoking.

Comparison of process parameters for microencapsulation of plasmid DNA in poly(D,L-lactic-co-glycolic) acid microspheres

Poly(D,L-lactic-co-glycolic) acid (PLGA) microspheres containing plasmid DNA encoding the firefly luciferase gene were prepared using the water-in-oil-in-water (w/o/w) double emulsion and solvent evaporation method. In this study, we investigated the effects of three process parameters on DNA microencapsulation: (1) emulsification method used to generate the primary emulsion, (2) water/oil ratio during formation of the first emulsion, and (3) surfactant concentration used in the preparation of the second emulsion. The resulting formulations were also analyzed for microsphere size, encapsulation efficiency, and kinetics of DNA release. We found that although each process alteration resulted in encapsulation of biologically active, structurally intact DNA, the surfactant and water/oil ratio significantly affected the size, release kinetics and encapsulation efficiency of plasmid DNA.

[Effect of cigarette smoke extract on E-cadherin expression of airway epithelial cells]

OBJECTIVE

To explore the possible mechanism of injury by smoking, and the effect of cigarette smoke extract (CSE) on E-cadherin (ECD) expression in airway epithelial cells (AEC) was observed.

METHODS

Mouse trachea and pig AEC were cultured in vitro. After CSE exposure, the expression of ECD in AECs was evaluated using immunohistochemical stain and image analysis.

RESULTS

ECD was distributed on the plasma membrane at the cell junctions of AECs. At 12th and 24th hour after CSE exposure, the ECD expression on membrane decreased, whereas the cytoplasmic expression increased (P < 0.01) as compared with the normal controls. The expression at 24th hour was higher than that at 12th hour (P < 0.01).

CONCLUSIONS

CSE decreases the membranous expression of ECD in AECs, but increases the cytoplasmic expression. The change of ECD expression may mediate the airway epithelial injuries by smoking.

The CLAVATA1 receptor-like kinase requires CLAVATA3 for its assembly into a signaling complex that includes KAPP and a Rho-related protein

The CLAVATA1 (CLV1) and CLAVATA3 (CLV3) genes are required to maintain the balance between cell proliferation and organ formation at the Arabidopsis shoot and flower meristems. CLV1 encodes a receptor-like protein kinase. We have found that CLV1 is present in two protein complexes in vivo. One is approximately 185 kD, and the other is approximately 450 kD. In each complex, CLV1 is part of a disulfide-linked multimer of approximately 185 kD. The 450-kD complex contains the protein phosphatase KAPP, which is a negative regulator of CLV1 signaling, and a Rho GTPase-related protein. In clv1 and clv3 mutants, CLV1 is found primarily in the 185-kD complex. We propose that CLV1 is present as an inactive disulfide-linked heterodimer and that CLV3 functions to promote the assembly of the active 450-kD complex, which then relays signal transduction through a Rho GTPase.

The Interfacial Polarization-Induced Electrorheological Effect

The Wagner theory, which describes the interfacial polarization in heterogeneous systems, was employed to model the electrorheological (ER) effect under the presumption that the shear stress increment is induced by the interfacial polarization. The currently observed experimental facts, such as the yield stress of some ER fluids, decreases with the applied field frequency increasing or the environment temperature decreasing, while that of other fluids increases with the frequency decreasing or temperature increasing; the strongest ER effect is usually observed in the suspension with the dispersed particle conductivity around 10(-7) S/m; the particle dielectric loss tangent of a good ER fluid usually is above 0.10 at 1000 Hz; and the fluid with a high conductive particle usually has a short response time, can be satisfactorily understood with the extended Wagner model. The Wagner-polarization-induced maximum yield stress of a heterogeneous-type ER fluid is estimated around 7 kPa under the presumption that the dielectric constants of the solid particle and the liquid medium are 10 and 2, respectively, the particle volume fraction is 35%, and the applied electric field strength is 3 kV/mm. It is concluded that the ER effect may substantially correlate with the Wagner polarization, which would help in understanding the mechanism of the ER effect and would provide a strategy for designing high performance ER fluids. Copyright 1998 Academic Press.

Correlation of the Dielectric Properties of Dispersed Particles with the Electrorheological Effect

The dc field rheological properties and frequency dependent dielectric properties of a set of electrorheological (ER) fluids composed of oxidized polyacrylonitrile or aluminosilicate materials dispersed in silicone oil were examined in this paper. Our experimental investigations show that there is a complicated relationship between the dielectric properties of dispersed particles and the ER effect. The dielectric loss of dispersed particles, which has not attracted much attention in previous work, was found to play a considerable role in ER response. The large dielectric loss tangent, experimentally around 0.10 at 1000 Hz, is found to be needed for a strong ER effect. A good ER solid material should first have large dielectric loss, and then the higher the dielectric constant, the stronger the ER effect. The large dielectric loss would facilitate the turning of dispersed particles, and the high dielectric constant would maintain the fibrillation structure stable and strong. Two processes, the particle turning process and the particle polarization process, are thought to be involved in ER activity. Our findings, in connection with the Wagner model, can better explain why the strongest ER effect occurs at particle conductivity of 10(-7) S/m; why the shear stress of some ER fluids decreases with frequency while with others the shear stress increases with frequency; and why trace water can enhance the ER effect considerably, which would help in understanding the mechanism of the ER effect. Too large a dielectric loss is thought to be unfavorable for the ER effect, and its suitable range is worth further study. The results also present a method of designing high performance ER fluids, which would significantly promote development of electrorheology and its application in industrial areas.

Microstructure-Confined Mechanical and Electric Properties of the Electrorheological Fluids under the Oscillatory Mechanical Field

The dynamic properties of two kinds of aluminosilicate-based electrorheological (ER) fluids were investigated under on-state and off-state electric fields. The dynamic responsive (frequency sweep spectrum and strain sweep spectrum) differences between these two ER suspensions were found under the off-state electric field, whereas similarities were observed once an external electric field was applied. Their dc conductances under an oscillatory mechanical field and their mechanical strengths under an oscillatory electric field were also examined. The periodically varied dc current in an oscillatory mechanical field and the decreased shear stress in an ac field were both found in these ER suspensions. The different in situ microstructures of these two ER fluids suggested on the basis of the percolation model, as well as their different response times measured experimentally, were presented to understand the experimental observations. Our results have a direct implication concerning the practical application of ER fluids.

The Conductivity Confined Temperature Dependence of Water-Free Electrorheological Fluids

The shear stresses and the current densities of four sorts of water-free ER fluids, two oxidized polyacrylonitriles-based and two aluminosilicates-based, were investigated at elevated and reduced temperatures in order to elucidate the operating mechanism. The complicated relationships among the mechanical properties, the current density, and temperature were especially addressed. The Wagner model was introduced to interpret our observations, instead of the commonly used conductivity model. It is found that the conductivity of the dispersed particles determines the temperature dependence of the shear stress and the current density of an ER fluid. Our findings have direct implication for the design of industrially required ER fluids and would be significant for ER applications.