[Clinical characteristics of 42 children with focal atrial tachycardia originated from the right atrial appendage]

Objective: To investigate the feature and treatment of atrial tachycardia (AT) originated from right atrial appendage (RAA) in children. Methods: The data of 42 children with AT originated from RAA, who were admitted the First Hospital of Tsinghua University from January 2010 to September 2022 were analyzed retrospectively.The clinical characteristics, treatment and efficacy were analyzed. The children were divided into tachycardia cardiomyopathy group and normal cardiac function group. The differences in the ablation age and the heart rate during AT between two groups were compared by independent sample t-test. Results: Among 42 children, there were 20 males and 22 females. The age of onset was 2.7 (0.6, 5.1) years. Their age at radiofrequency ablation was (6.5±3.6) years, and the weight was (23.4±10.0) kg. Thirty-two children (76%) had sustained AT. The incidence of tachycardia cardiomyopathy was 43% (18/42). Compared to that of the normal cardiac function group, the ablation age and the heart rate at atrial tachycardia of the tachycardia cardiomyopathy group were higher ((8.1±3.8) vs. (5.3±3.1) years, t=-2.63, P=0.012; (173±41) vs. (150±30) beats per minute, t=-2.05, P=0.047. Thirty-eight children (90%) responded poorly to two or more antiarrhythmic drugs. The immediate success rate of radiofrequency ablation (RFCA) was 57% (24/42), and the AT recurrence rate was 17% (4/24). Twenty-two children underwent RAA resection, and their AT were all converted to sinus rhythm after the surgery. During the RAA resection, 10 cases of right atrial appendage aneurysm were found, 9/18 of which failed the RFCA. Conclusions: The AT originated from the RAA in children tend to present with sustained AT, respond poorly to antiarrhythmic drugs, and has a low success rate of RFCA as well as high recurrence rate. Resection of the RAA is a safe and effective complementary treatment.

Collagen changes in rabbit conjunctiva after conjunctival crosslinking

This study aims to determine the ultrastructural changes in collagen fibrils in rabbit conjunctiva after conjunctival crosslinking using riboflavin and ultraviolet A (UVA) light at an irradiation intensity of 45 mW/cm². Conjunctival crosslinking may increase conjunctival stiffness. The supertemporal quadrants of the right eyes of 24 adult rabbits were treated with a topical riboflavin solution (0.25%) before irradiation with UVA light at 45 mW/cm² for 4 min. After 3 weeks, the collagen fibrils in fibril bundles were examined by electron microscopy. Immunohistochemical staining was used to detect the expression levels of collagen I and collagen III in the rabbits' conjunctiva. The diameter of the collagen fibrils in the fibril bundles varied slightly, ranging from 30 to 60 nm in the conjunctival stroma of the control group. In the treatment group, the diameter of collagen fibrils ranged from 60 to 90 nm. The thickest collagen fibrils were observed in the treatment group (up to 90 nm in diameter). In contrast, those in the conjunctival stroma of the control group were considerably smaller (up to 60 nm in diameter). However, thicknesses of collagen fibrils displayed a unimodal distribution. Both collagen I and collagen III increased after treatment with riboflavin and UVA light irradiation at 45 mW/cm². The data indicate that in rabbits, conjunctival crosslinking with riboflavin and UVA light at 45 mW/cm² for 4 min is safe and does not induce ultrastructural alterations of the conjunctival cells. The conjunctival crosslinking with riboflavin and UVA light at 45 mW/cm² can increase the diameter of collagen fibrils, but the average densities of collagen I and collagen III have no statistical significance.

[Effectiveness investigation on left bundle branch area pacing in 10 infants and toddlers]

Objective: To explore the feasibility, safety and effectiveness of left bundle branch area pacing (LBBAP) in children aged ≤3 years. Methods: A total of 10 children aged ≤3 years who were diagnosed with brady arrhythmia in the First Hospital of Tsinghua University from September 2020 to September 2021 were retrospectively analyzed. All the children met the indication of permanent pacemaker implantation and underwent LBBAP successfully. The intraoperative data (pacing parameters, electrocardiogram and radiographic imaging), cardiac ultrasound data and clinical data during regular postoperative follow-up were recorded. The preoperative and postoperative data were compared using matched samples t test. Results: Ten children (aged (1.6±0.7) years with weight of (10.3±2.5) kg) underwent LBBAP successfully. The QRS wave duration on the postoperative electrocardiogram was (100±9) ms, and the percentage of ventricular pacing was (97±7)%. The postoperative follow-up period was 6 (6, 12) months. At 1 week after operation, the left ventricular end-diastolic diameter Z scores in these children reduced significantly compared with those before operation (1.3±0.6 vs. 3.6±1.1, t=9.37, P<0.001). During the follow-up period, cardiac function was normal and the last left ventricular ejection fraction was (66±4)% in all children. At the last follow-up, the pacing threshold of the 10 children was smaller than 1.0 V and was acceptable. Compared with the intraoperative baseline values, the pacing threshold was slightly higher ((0.8±0.1) vs. (0.5±0.1) V, t=-5.27, P=0.001). However, no significant difference was found regarding sensing threshold ((16±5) vs. (14±4) mV, t=-0.83, P=0.426) and impedance ((584±88) vs. (652±86) Ω, t=2.26, P=0.050). During follow-up, no electrode related complications were recorded. Conclusions: LBBAP is safe and effective for infants and toddlers. Narrow QRS pacing with stable pacing parameters and normal cardiac function could be achieved postoperatively.

[GnRH-a combined fertility-sparing re-treatment in women with endometrial carcinoma or atypical endomertial hyperplasia who failed to oral progestin therapy]

Objective: To analyze the clinical efficacy and pregnancy outcomes of gonadotropin-releasing hormone agonist (GnRH-a) based fertility-sparing re-treatment in women with endometrial carcinoma (EC) and atypical endometrial hyperplasia (AEH) who failed with oral progestin therapy. Methods: Forty cases with EC or AEH who failed to respond to oral progestin were included from January 2012 to December 2020 at Peking Union Medical College Hospital. Combination of GnRH-a with levonorgestrel-releasing intrauterine system (group GLI: a subcutaneous injection of GnRH-a every 4 weeks and LNG-IUS insertion constantly) or the combination of GnRH-a with aromatase inhibitor (group GAI: a subcutaneous injection of GnRH-a every 4 weeks and oral letrozole 2.5 mg, daily) were used for these patients. Histological evaluation were performed at the end of each course (every 3-4 months) by hysteroscopy and curettage. After the complete remission (CR), all patients were followed up regularly. Results: (1) Clinical characteristics:among the 40 patients with EC or AEH, the median age at diagnosis was 31 years (range: 22-40 years) and the median body mass index was 24.7 kg/m² (range: 18.9-39.5 kg/m²). (2) Efficacy of fertility-sparing re-treatment: 37 (92%, 37/40) patients achieved CR, 6 (6/7) in AEH and 31 (94%, 31/33) in EC patients. The CR rate was 93% (26/28) and 11/12 in group GLI and GAI, respectively. The median time to CR was 5 months (range: 3-12 months). At the end of the first therapy course, the CR rates in AEH and EC were 5/7 and 42% (14/33), at the second course, the CR rates were 6/7 and 82% (27/33), respectively. (3) Recurrence: after 25 months of median follow-up duration (range: 10-75 months), 8 (22%, 8/37) women developed recurrence, 1/6 in AEH and 7 (23%, 7/31) in EC patients, with the median recurrence time of 18 months (range: 9-26 months). Among them, two cases who had completed childbirth chose to receive hysterectomy directly. Six patients met the criteria of fertility-preserving therapy and received conservative treatment again and 5 (5/6) of them achieved CR. (4) Pregnancy: of the 37 patients with CR, 33 desired to conceive. Ten women attempted to get pregnancy spontaneously and 23 cases with assisted reproductive technology. Fourteen (42%, 14/33) patients became pregnant, including 9 (27%, 9/33) live births, 3 (9%, 3/33) missed abortions, and 2 (6%, 2/33) miscarriages at the second trimester. Conclusions: GnRH-a based fertility-sparing re-treatment in AEH or EC patients who failed with oral progestin therapy achieved good treatment effect and reproductive outcomes. It is an encouraging alternative regime for patients who failed with oral progestin therapy.

Macrophages Promote Growth of Squamous Cancer Independent of T cells

Oral cancers, primarily squamous cell carcinomas (SCCs), progress either slowly or aggressively. Here we assessed the role of macrophages in SCC behavior. We used mouse SCC cells derived from tumors harboring a Kras^G12D activation mutation and Smad4 deletion in keratin 15-positive stem cells and a human oral SCC cell line, FaDu, which has NRAS amplification and SMAD4 deletion. SCC cells were transplanted into immune-compromised or immune-competent (syngeneic) recipients. After tumors were established, we used clodronate liposomes to ablate macrophages. We found that the number of tumor-associated macrophages (TAMs) was not affected by the presence of T cells but differed considerably among tumors derived from different SCC lines. Clodronate significantly reduced TAMs and splenic macrophages, resulting in reduced SCC volumes. Tumors with clodronate treatment did not show decreased proliferation but did exhibit increased apoptosis and reduced vascular density. FLIP (Fas-associated via death domain-like interleukin 1β-converting enzyme inhibitory protein), an apoptosis inhibitor abundantly produced in tumor cells and TAMs, was reduced in tumor cells of clodronate-treated mice. Reduced FLIP levels correlated with reductions in phosphorylated nuclear NFκB p65 and NFκB inhibitor attenuated FLIP protein levels in SCC cells. Furthermore, TGFβ1 serum levels and pSmad3 were reduced in clodronate-treated mice, but their reductions were insufficient to reverse epithelial-mesenchymal transition or TGFβ-mediated angiogenesis in endothelial cells. Consequently, metastasis was not significantly reduced by macrophage reduction. However, reduced pSmad3 correlated with reduction of its transcriptional target, vascular endothelial growth factor A, in clodronate-treated tumor cells, which correlated with reduced vascular density in clodronate-treated tumors. Taken together, our study revealed that macrophages contribute to SCC expansion through interactions with tumor cells but are dispensable for SCC metastasis. Our study provides novel insights into understanding the contributions and limitations of TAMs in SCC progression.

[Results of microscopic examinations and blood slide re-examinations of malaria elimination evaluation in ten prefectures of Yunnan Province]

OBJECTIVE

To understand the laboratory technicians' abilities in blood slide making and reading in 10 prefectures of Yunnan Province which have passed the provincial malaria elimination evaluation, so as to provide the evidence for improving the malaria elimination surveillance and parasite examination.

METHODS

Thirty negative blood slides were randomly sampled to evaluate coating, dyeing and clean quality and reading results, and 4 laboratory technicians were sampled to evaluate their reading abilities from each prefecture level and its 2 subordinate counties (districts) respectively, and then the results were analyzed.

RESULTS

A total of 869 negative blood samples were evaluated. The coincidence rate was 100%. The proportions of good coating, dyeing and clean quality were 96.09%, 91.71% and 96.89%, respectively. Totally 576 blood slides were used to evaluate the reading ability. The number of correct reading was 505, and the correct rate was 87.67%. Among them, the Plasmodium vivax correct reading rate was 87.76%, the P. falciparum correct reading rate was 87.50%, and the correct reading rate of mixed infections was 47.62%. The laboratory technicians' ability to the mixed infections was significantly lower than the ability to the others (χ² = 37.169, P < 0.05), however, in the laboratory technicians' abilities, there was no significant difference among the center (s) for disease control and prevention, general hospitals and township hospitals (χ² = 2.782, P > 0.05), and the prefecture, county and township levels (χ² = 0.358, P > 0.05) .

CONCLUSIONS

The 10 prefectures have passed the provincial evaluation in blood slide making and microscopic examination skill indicators requested, but the medical and public health institutions at all levels still should further improve their laboratory technicians' abilities in blood slide making and microscopic examination skills.

A preliminary study on the establishment of an animal model of conjunctivochalasis

AIM

To explore a feasible method on the establishment of an animal model of conjunctivochalasis (CCH).

METHODS

Twelve clean-grade New Zealand white rabbits were divided into four groups (n=3/group): the control group (one received no interventions, and the others underwent subconjunctival injection of sterile water), the matrix metalloproteinases (MMPs) group (administered subconjunctival injection of MMP-3), the aging group (administered subcutaneous injection of D-galactose), the tumor necrosis factor-α (TNF-α) solution group (administered eye drops of TNF-α). Anterior segment photography, conjunctival tissue light microscopy and transmission electron microscopy (TEM) were performed after 12wk.

RESULTS

Among all groups, the MMPs group had the following changes: the looser connection between the inferior bulbar conjunctiva and sclera; the more disordered collagen fibers (Trichrome staining) and the broken elastic fibers (Aldehyde-fuchsin staining); the focal necrosis of fibroblasts (TEM).

CONCLUSION

Administration of MMPs may be a feasible method for the establishment of an animal model of CCH.

Mouse Models for Studying Oral Cancer: Impact in the Era of Cancer Immunotherapy

Model systems for oral cancer research have progressed from tumor epithelial cell cultures to in vivo systems that mimic oral cancer genetics, pathological characteristics, and tumor-stroma interactions of oral cancer patients. In the era of cancer immunotherapy, it is imperative to use model systems to test oral cancer prevention and therapeutic interventions in the presence of an immune system and to discover mechanisms of stromal contributions to oral cancer carcinogenesis. Here, we review in vivo mouse model systems commonly used for studying oral cancer and discuss the impact these models are having in advancing basic mechanisms, chemoprevention, and therapeutic intervention of oral cancer while highlighting recent discoveries concerning the role of immune cells in oral cancer. Improvements to in vivo model systems that highly recapitulate human oral cancer hold the key to identifying features of oral cancer initiation, progression, and invasion as well as molecular and cellular targets for prevention, therapeutic response, and immunotherapy development.

[Relationship between the Change Rules of Volatile Organic Compounds in Rat Muscle and Postmortem Interval]

OBJECTIVES

To explore the relationship between the change rules of volatile organic compounds （VOCs） in rat muscle and postmortem interval （PMI）.

METHODS

A total of 120 healthy rats were divided randomly into 12 groups （10 for each group）. After the rats were sacrificed by cervical dislocation, the bodies were kept at （25±1） ℃. Rat muscle samples were separately obtained at 12 PMI points, including 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 d. The VOCs in rat muscles were collected, detected and analyzed by headspace solid-phase microextraction （HS-SPME） coupled to gas chromatography-mass spectrometer （GC-MS）.

RESULTS

In total, 15 species of VOCs were identified, including 9 aromatic compounds, 3 sulfur compounds, 2 aliphatic acids and 1 heterocyclic compound. The species of VOCs increased with PMI： no species were detected within 1 day, 3 species were detected on day 2, 9 on day 3, 11 on day 4, 14 from day 5 to 7, and 15 from day 8 to 10. Total peak area of 15 species of VOCs was significantly correlated to PMI （adjusted R²=0.15-0.96）： the regression function was y=-17.05 x²+ 164.36 x-246.36 （adjusted R²=0.96） from day 2 to 5, and y=2.24 x+101.13 （adjusted R²=0.97） from day 6 to 10.

CONCLUSIONS

The change rules of VOCs in rat muscle are helpful for PMI estimation.

Expressions of matrix metalloproteinases 1 and 3 and their tissue inhibitors in the conjunctival tissue and fibroblasts cultured from conjunctivochalasis

AIM

To investigate the expression of matrix metalloproteinases 1 and 3 (MMP-1 and MMP-3) and their tissue inhibitors of metalloproteinases 1 and 3 (TIMP-1 and TIMP-3) in the conjunctiva of eyes with conjunctivochalasis (CCh).

METHODS

The conjunctival tissue was obtained from the CCh patients and controls, the MMPs/TIMPs expression concentration was determined by enzyme-linked immuno-sorbent assay (ELISA) and immunofluorescence staining. The expression levels of MMPs/TIMPs in the CCh fibro-blasts were determined by analyzing its concentration in the cellular supernatant that was abstracted from the in vitro cultured CCh fibroblasts.

RESULTS

MMP-1 and MMP-3 levels determined by ELISA were both significantly higher in the CCh group than that in the control group (P=0.042, 0.022, respectively), so was the levels of TIMP-1 (P=0.010). No significant difference in the expression of TIMP-3 in conjunctiva was found between the two groups (P=0.298). The expression of MMP-1 and MMP-3 were both up-regulated significantly in the CCh group (P=0.040, 0.001, respectively) on immuno-fluorescence staining. MMP-1 and MMP-3 expression in the fibroblasts were both significantly higher in the CCh group than that in the control group (P=0.027, 0.001, respectively), while neither the TIMP-1 nor TIMP-3 expression was significantly different between the two groups (P=0.421, 0.237, respectively).

CONCLUSION

The overexpression of MMP-1 and MMP-3 in conjunctival tissue and fibroblasts may play an important role in the pathogenesis and development of CCh.

Influences of high-voltage electrical burns on the pulmonary microcirculation in rabbits

This study was performed to investigate the effects of high-voltage electrical burns (HEB) on the pulmonary microcirculation in rabbits. Total of 120 rabbits were randomly divided into control and HEB group using a random number table. HEB model was developed with a voltage regulator and experimental transformer. Laser Doppler perfusion imager was utilized to monitor and quantify the blood perfusion in pulmonary microcirculation. The microvascular morphologic changes of the lung were observed using light microscopy and transmission electron microscope (TEM). The lung wet/dry weight ratio and the PaO2 were determined. The values of blood perfusion in rabbit pulmonary microcirculation in the HEB group were decreased at 5 min, but increased at 1 h after burn (P <  0.01) and then decreased gradually. Light microscopy reveals microthrombus formation in pulmonary venules and bleeding in venous capillaries in HEB group. We found the number of microvilli in the capillary endothelial cells decreased, the rough endoplasmic reticulum expanded and severe degranulation occurred, the mitochondrial cristae fused or disappeared, and severe edema surrounded the capillary endothelial cells by TEM. The values of lung wet/dry weight ratio were higher and the PaO2 were lower than that of before burn group (P <  0.01). These results demonstrated that microcirculatory disorders play a major role in the development of progressive lung damage after high-voltage electrical burns.

Effects of carbomer eye drops in combination with orthokeratology lens in treating adolescent myopia

To investigate the effects of carbomer eye drops (CED) during long-time wearing of overnight orthokeratology lens of adolescents with myopia, 260 teenagers with myopia treated in the Henan Provincial People’s Hospital from June 2012 to August 2014 and followed-up for more than 2 years were enrolled. All the patients underwent regular fitting of orthokeratology lens. They were divided into a CED (Vidisic) group (130 cases, 260 eyes treated with CED) and rewetting drops (RD) (Baushe and Lomb) group (130 cases, 260 eyes treated with RD). The effects in the two groups were observed. The incidence of corneal epithelial defects one day, one week and one month after treatment of the CED group was lower than that of the RD group, and the difference was statistically significant (P less than 0.05); the tear break up time (TBUT) of the CED group was higher than that of the RD group at different time points, and the difference had statistical significance (P less than 0.05); the difference of the value of Schirmer I test between the two groups had no statistical significance (P>0.05). It is concluded that carbomer eye drops can stabilize tear film and protect and repair corneal epithelium during the wearing of orthokeratology lens.

Construction and characterization of recombinant adenovirus carrying a mouse TIGIT-GFP gene

Recombinant adenovirus vector systems have been used extensively in protein research and gene therapy. However, the construction and characterization of recombinant adenovirus is a tedious and time-consuming process. TIGIT is a recently discovered immunosuppressive molecule that plays an important role in maintaining immunological balance. The construction of recombinant adenovirus mediating TIGIT expression must be simplified to facilitate its use in the study of TIGIT. In this study, the TIGIT gene was combined with green fluorescent protein (GFP); the TIGIT-GFP gene was inserted into a gateway plasmid to construct a TIGIT-GFP adenovirus. HEK 293A cells were infected with the adenovirus, which was then purified and subjected to virus titering. TIGIT-GFP adenovirus was characterized by flow cytometry and immunofluorescence, and its expression in mouse liver was detected by infection through caudal vein injection. The results showed the successful construction of the TIGIT-GFP adenovirus (5 x 10(10) PFU/mL). Co-expression of TIGIT and GFP was identified in 293A and liver cells; synthesis and positioning of TIGIT-GFP was viewed under a fluorescence microscope. TIGIT-GFP was highly expressed on liver cells 1 day (25.53%) after infection and faded 3 days (11.36%) after injection. In conclusion, the fusion of TIGIT with GFP allows easy, rapid, and uncomplicated detection of TIGIT translation. The construction of a TIGIT-GFP adenovirus, mediating TIGIT expression in vitro and in vivo, lays the foundation for further research into TIGIT function and gene therapy. Moreover, the TIGIT-GFP adenovirus is a helpful tool for studying other proteins (which could replace the TIGIT gene).

Efficacy of treatment for pterygium by autologous conjunctival transplantation and mitomycin C

BACKGROUND

The recurrence of pterygium after surgery is high. A variety of adjunctive treatment approaches have been developed to improve the clinical efficacy and many related articles have been published. This study aimed to determine the risk for postoperative pterygium recurrence comparing autologous conjunctival transplantation (ACT) versus mitomycin C (MMC).

METHODS

Relevant literature published until December 2010 in Medline, Embase, Cochrane, Cochrane library, Science Citation Index, and Google Scholar were searched. Qualified random clinical trial (RCT) studies on the comparison of recurrence rate of pterygium after ACT and MMC treatment were included in this study.

RESULTS

Eight RCTs with 663 eyes entered the final analysis. The recurrent rate of pterygium was 8.7% (30/343) for ACT and 18.75% (60/320) for MMC. Using fixed-effect meta analysis, we found that the recurrence was significantly lower after ACT than MMC treatment (odds ratio (OR) = 0.40, 95% confidence index (CI), 0.25 - 0.63, P < 0.0001). In sensitivity analyses, we employed random-effects model and excluded studies of low quality or studies in which MMC was administrated after the operation. All the sensitivity analyses confirmed that ACT led to lower recurrence rates than MMC. Sub-group analysis revealed that the recurrence rate was 20.2% (20/99) and 27.65% (26/94) for conjunctival autograft (CA) and MMC respectively, and no significant difference in the recurrence rate was detected (OR = 0.65, 95%CI 0.33 - 1.28, P = 0.22). However, we found that conjunctival limbal autograft (CLA) had lower recurrence rate than MMC (OR = 0.26, 95%CI 0.14 - 0.48, P = 0.0001).

CONCLUSION

CLA has better therapy efficacy against the recurrence of pterygium than MMC.

DNA methylation status in tissues of sheep clones

Genomic imprinting and DNA methylation play an important role in mammalian development. Many cloned animals showed heterogeneous DNA methylation profiles. However, there are fewer reports in cloned lambs because of a lack of genomic imprinting information. In this study, we investigated DNA methylation patterns in CpG islands and differentially methylated regions of putative imprinted gene Peg10 and imprinted genes Dlk1, Igf2R and H19 in cloned lambs. Five organs from two cloned lambs died shortly after birth and two normal controls were investigated. We observed normal DNA methylation profiles in cloned lambs. The imprinted genes Dlk1, Igf2R and H19 in livers, kidneys, hearts, muscles and lungs of the two cloned lambs exhibited relatively normal DNA methylation, except for Peg10 showing some differences between controls and cloned lambs. Our results indicate that somatic cell nuclear transfer-produced sheep exhibited relatively normal DNA methylation pattern and experienced normal DNA methylation reprogramming at imprinted loci.

Human papillomaviruses in oral carcinoma and oral potentially malignant disorders: a systematic review

OBJECTIVES

Human papillomavirus (HPV) in oral carcinoma (OSCC) and potentially malignant disorders (OPMD) is controversial. The primary aim was to calculate pooled risk estimates for the association of HPV with OSCC and OPMD when compared with healthy oral mucosa as controls. We also examined the effects of sampling techniques on HPV detection rates.

METHODS

Systematic review was performed using PubMed (January 1966-September 2010) and EMBASE (January 1990-September 2010). Eligible studies included randomized controlled, cohort and cross-sectional studies. Pooled data were analysed by calculating odds ratios, using a random effects model. Risk of bias was based on characteristics of study group, appropriateness of the control group and prospective design.

RESULTS

Of the 1121 publications identified, 39 cross-sectional studies met the inclusion criteria. Collectively, 1885 cases and 2248 controls of OSCC and 956 cases and 675 controls of OPMD were available for analysis. Significant association was found between pooled HPV-DNA detection and OSCC (OR = 3.98; 95% CI: 2.62-6.02) and even for HPV16 only (OR = 3.86; 95% CI: 2.16-6.86). HPV was also associated with OPMD (OR = 3.87; 95% CI: 2.87-5.21). In a subgroup analysis of OPMD, HPV was also associated with oral leukoplakia (OR = 4.03; 95% CI: 2.34-6.92), oral lichen planus (OR = 5.12; 95% CI: 2.40-10.93), and epithelial dysplasia (OR = 5.10; 95% CI: 2.03-12.80).

CONCLUSIONS

The results suggest a potentially important causal association between HPV and OSCC and OPMD.

Human papillomaviruses in oral carcinoma and oral potentially malignant disorders: a systematic review

OBJECTIVES

Human papillomavirus (HPV) in oral carcinoma (OSCC) and potentially malignant disorders (OPMD) is controversial. The primary aim was to calculate pooled risk estimates for the association of HPV with OSCC and OPMD when compared with healthy oral mucosa as controls. We also examined the effects of sampling techniques on HPV detection rates.

METHODS

Systematic review was performed using PubMed (January 1966-September 2010) and EMBASE (January 1990-September 2010). Eligible studies included randomized controlled, cohort and cross-sectional studies. Pooled data were analysed by calculating odds ratios, using a random effects model. Risk of bias was based on characteristics of study group, appropriateness of the control group and prospective design.

RESULTS

Of the 1121 publications identified, 39 cross-sectional studies met the inclusion criteria. Collectively, 1885 cases and 2248 controls of OSCC and 956 cases and 675 controls of OPMD were available for analysis. Significant association was found between pooled HPV-DNA detection and OSCC (OR = 3.98; 95% CI: 2.62-6.02) and even for HPV16 only (OR = 3.86; 95% CI: 2.16-6.86). HPV was also associated with OPMD (OR = 3.87; 95% CI: 2.87-5.21). In a subgroup analysis of OPMD, HPV was also associated with oral leukoplakia (OR = 4.03; 95% CI: 2.34-6.92), oral lichen planus (OR = 5.12; 95% CI: 2.40-10.93), and epithelial dysplasia (OR = 5.10; 95% CI: 2.03-12.80).

CONCLUSIONS

The results suggest a potentially important causal association between HPV and OSCC and OPMD.

Fabrication and characterization of elastomeric polyester/carbon nanotubes nanocomposites for biomedical application

A novel biodegradable polymer elastomer nanocomposite composing of poly(1,8-octanediol-citrate) (POC) polymer matrix and carbon nanotubes (CNTs) additive was successfully fabricated and systematically investigated using Fourier transform infrared (FT-IR), X-ray diffractometer (XRD), differential scanning calorimetry (DSC), tensile test, incubation and cytotoxicity tests. It was found that the addition of CNTs in POC elastomer did not result in any noticeable change in its chemical structure and the amorphous state. However, the tensile strength and elongation at break were greatly improved by the addition of CNTs in POC polymer matrix. It revealed that the swelling ratio and percentage of weight loss of POC/CNTs nanocomposite were lower, compared with the pure POC material. Moreover, the adsorption amount of bovine serum albumin (BSA) increased with an increase of the CNTs mass content in POC matrix revealing the enhanced hydrophilicity of POC/CNTs nanocomposites contributed by the carboxyl of the CNTs. Additionally, the cytotoxicity tests with L929 cell line revealed that the experimental POC/CNTs nanocomposites possessed good in vitro biocompatibility.

Suppression of PPN/MG61 attenuates Wnt/beta-catenin signaling pathway and induces apoptosis in human lung cancer

Wingless and int homologue (Wnt) family proteins have been shown to have important roles in the decision of cell fate and behavior at multiple stages during the development and tumorigenesis. One of the Drosophila segment polarity genes, porcupine (porc) gene, encodes an evolutionarily conserved endoplasmic reticulum membrane protein involving in the post-translational processing of the Wnt family proteins. Here, we report that human homologue of Drosophila porc gene, PPN/MG61, was abundantly expressed in human cancer cell lines, but not in normal cells. We also found that PPN/MG61 was overexpressed in primary lung cancer tissue samples, compared to their matched normal tissue samples. Furthermore, when we used small interfering RNA to knock down PPN/MG61 mRNA in lung cancer cells expressing the gene, we observed apoptosis induction, along with decreased activity of Wnt pathway in those lung cancer cells. These data suggest that PPN/MG61 may be a novel marker for human lung cancer and that post-translational modification of the Wnt signal molecules by PPN/MG61 may be important for the function of Wnt pathway in lung cancer.

Ca2+Cascade and Meiotic Resumption of the Caprine Primary Oocyte

In this study, we investigated the fluctuations of concentration of intracytoplasmic free Ca(2+) during in vitro maturation of caprine primary oocytes and its role in meiotic resumption. Oocytes that were extracted from caprine ovaries were cultured and allowed to mature in vitro to determine their developmental stages including germinal vesicle (GV), germinal vesicle breakdown (GVBD), metaphase of the first meiotic division (MI) and metaphase of the second meiotic division (MII). Intracytoplasmic free Ca(2+) turnovers of caprine oocytes at these different developmental stages were measured using the calcium fluorescent probe Fura-2/AM (C(44)H(47)N(3)O(24)) to investigate the dynamics of cytosolic free Ca(2+) during in vitro maturation of oocytes and the role of Ca(2+) in inducing the initiation of meiotic resumption of oocytes. Moreover, the oocytes were cultured in Ca(2+) culture medium and Ca(2+)-free culture medium to examine the effect of extracellular Ca(2+) on the oocyte maturation. The results indicated that Ca(2+) concentrations at GV, GVBD, MI and MII stages were 78.06, 147.41, 126.97 and 97.73 nmol/l, respectively, and that 86.30% of oocytes remained at the GV stage and no oocyte developed to MII in Ca(2+)-free culture medium, and 1.1% of oocytes stayed at the GV stage and 83.5% of oocytes developed to MII in Ca(2+) culture medium. These results suggest that the occurrence of GVBD and cell cycle progression to MI and MII stages are closely related to Ca(2+), and that extracellular Ca(2+) performs a specific function for the initiation of meiotic resumption in caprine oocytes.

Isolation and propagation of keratinocytes derived from Cashmere goat fetus

The study was conducted to isolate epidermal keratinocytes from Cashmere goat fetus with the aim to develop suitable conditions for keratinocyte cultivation and propagation. The methods developed for keratinocyte culture include (i) use of a feeder-layer of mitotically inactivated fibroblasts obtained from goat and mouse fetal skin, (ii) use of a substrate such as collagen IV, or (iii) without use of any substrate. Epidermal cell removal was established by enzymatically separating keratinocytes from 12 to 16 weeks aged fetal skin tissues treated with 0.125% trypsin solution overnight at 4 degrees C. The cells were maintained in all culture conditions with serum containing medium. Keratinocyte multiplication and proliferation were comparable in different culture conditions and the improved cellular attachment and growth have been obtained in cultures on feeder layers. Colony forming keratinocytes on feeder layer were heterogeneous in their growth potential. In feeder free conditions, high cellular density was required at plating for sub-cultivation as their poor attachment in culture dishes. This study reports the comparative efficacy of different culture conditions for keratinocyte isolation and in vitro propagation originating from Cashmere goat fetus.

In vitro growth and maturation of caprine oocytes

This study was conducted to culture in vitro caprine pre-antral follicles for determining the competence of growth and maturation of oocytes and establishing a suitable culture system for oocyte maturation from pre-antral follicles. Two different culture methods (microdrop and agar gel clot) were employed to culture caprine pre-antral follicles. The pre-antral follicles were isolated from prepubertal goat ovaries by treatment with collagenase and DNase. The isolated pre-antral follicles were cultured in basic culture medium for 9 days (for growth). And oocytes were cultured in maturation culture medium for another 2 days for maturation. The result demonstrated that the growth rate of oocytes cultured in microdrops was significantly (p < 0.05) higher than that in agar gel clots, whereas the viability of oocytes in microdrops was considerably (p < 0.05) lower than that in agar gel clots. The oocytes grew over 150 microm in diameter, and two of 151 oocytes cultured in microdrops yielded morphologically abnormal first polar bodies. However, the size of oocytes cultured in agar gel approached to 120 microm in diameter and no polar body was produced.

Separation, cultivation and biological characteristics of oral carcinoma-associated fibroblasts

OBJECTIVES

Carcinoma-associated fibroblasts (CAFs) have been suggested to regulate the initiation and progression of many types of solid tumors. The aim of the study was to separate, cultivate, identify oral CAFs, and to investigate their biological characteristics.

MATERIALS AND METHODS

The primary CAFs and normal fibroblasts (NFs) of the tongue were obtained by tissue culture. Then cells were dissociated by 0.25% trypsin and purified by curettage method combining with trypsinization. The cells were verified according to morphological observation and immunohistochemical staining of certain proteins. Multiple proliferation indexes and karyotype of the cells were assayed.

RESULTS

Third passage purified oral CAFs and NFs were attained successfully. The morphological characteristics of the CAFs changed significantly comparing to the NFs. The CAFs showed positive staining for vimentin, alpha-smooth muscle actin and matrix metalloproteinases-2. The proliferation and mitosis ability of the CAFs were significantly increased compared with the NFs (P < 0.05). No karyotypic abnormalities were found in the CAFs.

CONCLUSIONS

There were obvious differences in the biological characteristics between oral CAFs and NFs. The results may provide us an experimental foundation for further studies on the roles of CAFs in the initiation and progression of oral cancer.

Magnesium supplementation prevents chronic cyclosporine nephrotoxicity via adjusting nitric oxide synthase activity

INTRODUCTION

Nitric oxide synthase (NOS) is a protective factor for chronic cyclosporine nephrotoxicity by virtue of adjusting the production of nitric oxide (NO). The aim of this study was to explore the role of NOS in the effect of magnesium supplementation to prevent chronic cyclosporine nephrotoxicity.

METHODS

Rats maintained on a low-salt diet were divided into three groups: normal controls, cyclosporine group (CsA 15 mg x kg(-1) x d(-1) subcutaneously) and CsA + Mg2+ group (CsA subcutaneously and dietary supplementation with 0.6% Mg enriched by MgCl2). On day 28, plasma Mg2+, plasma creatinine, NOS activity, and NO content in renal tissue were examined. The renal expression of endothelial nitric oxide synthase (eNOS) and inducible nitric oxide synthase (iNOS) in kidneys was determined by an immunohistochemistry technique. The lesions of chronic cyclosporine nephrotoxicity were identified by HE and PAS stains as well as electron microscope.

RESULTS

After 28 days of CsA administration, characteristic histological lesions of chronic cyclosporine nephotoxicity were observed, including arteriolopathy, tubular atrophy and interstitial fibrosis. Giant mitochondria and microcalcifications were observed by electron microscopy. Simultaneously, constitutive nitric oxide synthase (cNOS) activity in kidneys was increased, but NO content did not increase correspondingly (P < .05) compared with normal controls. Dietary supplementation with Mg2+ ameliorated the CsA-induced histological lesions. cNOS activity was decreased to normal levels and NOS was increased (P < .05) compared with animals that only received CsA. CsA and magnesium supplementation did not change iNOS activity.

CONCLUSIONS

Dietary supplementation with Mg2+ seems to improve renal function and almost abolish CsA-induced histological lesions via altering the abnormal activation of cNOS in this model.

Inhibition of MD-1 expression by immunosuppressants or antisense oligodeoxynucleotides on skin allograft survival in mice

AIM

The aim of this study was to investigate the effects of inhibition of MD-1 expression using nonspecific immunosuppressants and specific antisense oligodeoxynucleotides (AS-ODNs) treatment on skin allograft survival in mice.

METHODS

C57BL/6 to Balb/c skin allograft model was used in all groups, followed by Cyclosporine (CsA), Tacrolimus (FK506), Mycophenolate Mofetil (MMF), and Sirolimus (SRL) intraperitaneally, as well as AS-ODNs intravenously. Recipients were humanely killed at 11 days after transplantation. MD-1 expression was determined using flow cytometric analysis (FACS). AlamarBlue was used to evaluate proliferation. And serum levels of interleukin (IL)-2 and IL-10 were detected using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared with saline controls, the mean survival times (MST) of skin allografts in all of the immunosuppressants and AS-ODNs treated groups were significantly prolonged (P < .05). CsA, MMF, and AS-ODNs inhibited MD-1 expression and lymphocyte proliferation, as well as decreased serum level of IL-2 and increased that of IL-10; FK506, treatment showed all the effects mentioned above but up-regulated the IL-10 level; SRL had no significant influence on either MD-1 expression or IL-2 and IL-10 level, although it equally suppressed the proliferation (P < .05 vs controls). The negative correlation between MD-1 expression and lymphocyte proliferation or IL-2 level was significant, as was the positive correlation between it and IL-10 level (P < .01).

CONCLUSIONS

CsA, FK506, MMF, and AS-ODNs can efficiently inhibit MD-1 expression. The effects of the immunosuppressants are seemingly associated with the down-regulation of the IL-2 serum level. MD-1 was theorized to play an important role in rejection promotion, although the precise relationship between it and allograft survival still remains ambiguous.

A direct continuous pH-spectrophotometric assay for arginine kinase activity

A direct and continuous spectrophotometric method was developed for determining arginine kinase (phosphoarginine synthesis) activity. Protons are produced during the phosphoarginine synthesis course, so adding the complex acid-base indicator to this solution and monitoring the decrease of absorbance of the solution at 575 nm will follow the arginine kinase activity. For this condition, one activity unit of arginine kinase was defined as 1 micromol H+ produced in 1 minute in the enzymatic reaction catalyzed by arginine kinase.

Kinetics of complexing activation by the magnesium ion on green crab (Scylla serrata) alkaline phosphatase

As with mammalian enzymes, green crab (Scylla serrata) alkaline phosphatase can be activated by Mg2+ through a time-dependent course. The activation is mainly a Vmax effect. Tsou's method was used to study the kinetic course of activation. The results show that the enzyme was activated by a complexing scheme that had not been previously identified: the enzyme first reversibly and quickly binds Mg2+ and then undergoes a slow reversible course to activation, with a relatively high activation energy (78 +/- 4 kJ/mol) and a slow conformational change. The activation reaction is a single molecule reaction, and the apparent activation rate constant is independent of Mg2+ concentration if the concentration is sufficiently high. The microscopic rate constants of activation and the association constant were determined from the measurements. The proposed scheme may also be applied to the Mg2+ activation mechanism for mammalian enzyme, to explain why the activation rate is time-dependent and not diffusion controlled. Substrate binding was also shown to affect the activation rate constant.

Folding pathway for partially folded rabbit muscle creatine kinase

Rabbit muscle creatine kinase (CK) was modified by 5,5'-dithio-bis(2-nitrobenzoic acid) accompanied by 3 M guanidine hydrochloride denaturation to produce a partially folded state with modified thiol groups. The partially folded CK was in a monomeric state detected by size exclusion chromatography, native-polyacrylamide gel electrophoresis, circular dichroism, and intrinsic fluorescence studies. After dithiothreitol (DTT) treatment, about 70% CK activity was regained with a two-phase kinetic course. Rate constants calculated for regaining of activity and refolding were compared with those for CK modified with various treatments to show that refolding and recovery of activity were synchronized. To further characterize the partially folded CK state and its folding pathway, the molecular chaperone GroEL was used to evaluate whether it can bind with partly folded CK during refolding, and 1-anilinonaphthalene-8-sulfonate was used to detect the hydrophobic surface of the monomeric state of CK. The monomeric state of CK did not bind with GroEL, although it had a larger area of hydrophobic surface relative to the native state. These results may provide different evidence for the structural requirement of GroEL recognition to the substrate protein compared with previously reported results that GroEL bound with substrate proteins mainly through hydrophobic surface. The present study provides data for a monomeric intermediate trapped by the modification of the SH groups during the refolding of CK. Schemes are given for explaining both the partial folding CK pathway and the refolding pathway.

Molecular mechanism for osmolyte protection of creatine kinase against guanidine denaturation

The effects of osmolytes, including dimethysulfoxide, sucrose, glycine and proline, on the unfolding and inactivation of guanidine-denatured creatine kinase were studied by observing the fluorescence emission spectra, the CD spectra and the inactivation of enzymatic activity. The results showed that low concentrations of dimethysulfoxide (< 40%), glycine (< 1.5 m), proline (< 2.5 m) and sucrose (< 1.2 m) reduced the inactivation and unfolding rate constants of creatine kinase, increased the change in transition free energy of inactivation and unfolding (Delta Delta G(u)) and stabilized its active conformation relative to the partially unfolded state with no osmolytes. In the presence of various osmolytes, the inactivation and unfolding dynamics of creatine kinase were related to the protein concentrations. These osmolytes protected creatine kinase against guanidine denaturation in a concentration-dependent manner. The ability of the osmolytes to protect creatine kinase against guanidine denaturation decreased in order from sucrose to glycine to proline. Dimethysulfoxide was considered separately. This study also suggests that osmolytes are not only energy substrates for metabolism and organic components in vivo, but also have an important physiological function for maintaining adequate rates of enzymatic catalysis and for stabilizing the protein secondary and tertiary conformations.

Chaperone-like activity of peptidyl-prolyl cis-trans isomerase during creatine kinase refolding

Porcine kidney 18 kD peptidyl-prolyl cis-trans isomerase (PPIase) belongs to the cyclophilin family that is inhibited by the immunosuppressive drug cyclosporin A. The chaperone activity of PPIase was studied using inactive, active, and alkylated PPIase during rabbit muscle creatine kinase (CK) refolding. The results showed that low concentration inactive or active PPIase was able to improve the refolding yields, while high concentration PPIase decreased the CK reactivation yields. Aggregation was inhibited by inactive or active PPIase, and completely suppressed at 32 or 80 times the CK concentration (2.7 microM). However, alkylated PPIase was not able to prevent CK aggregation. In addition, the ability of inactive PPIase to affect CK reactivation and prevent CK aggregation was weaker than that of active PPIase. These results indicate that PPIase interacted with the early folding intermediates of CK, thus preventing their aggregation in a concentration-dependent manner. PPIase exhibited chaperone-like activity during CK refolding. The results also suggest that the isomerase activity of PPIase was independent of the chaperone activity, and that the proper molar ratio was important for the chaperone activity of PPIase. The cysteine residues of PPIase may be a peptide binding site, and may be an essential group for the chaperone function.

Effects of acrylamide on creatine kinase from rabbit muscle

The mechanism of inhibition of creatine kinase (CK) by acrylamide (Acr) has been examined (in vitro). Within the concentration range of 0 to 1 M, Acr markedly inhibited CK and depleted the protein thiols. Both inactivation and thiol depletion were time- and Acr concentration-dependent. Addition of dithiothreitol (DTT) did not reactivate CK inactivated by Acr. However, CK with 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) pre-blocked thiols can be reactivated by DTT after incubation with Acr. The transition-state analogue also had a significant protective effect on CK against Acr inhibition. We conclude that thiol alkylation is a critical event in inactivation of CK by Acr. Furthermore, Acr binding to CK changed its surface charge, which may be the same effect for the toxicity of Acr towards other proteins.

Dissociation and unfolding of GCN4 leucine zipper in the presence of sodium dodecyl sulfate

The dissociation and unfolding behavior of the GCN4 leucine zipper has been studied using SDS titration. Circular dichroism (CD) spectra showed that the alpha-helix content of the leucine zipper (20 microM) decreased during the sodium dodecyl sulfate (SDS) titration. However, the alpha-helix content of the leucine zipper still remained significant in the presence of 1 mM SDS, with little change detected when the SDS concentration further increased to 2 mM. The dimer dissociation of the leucine zipper is also a co-operative process during SDS titration; with no dimer remaining when SDS concentration reached 1 mM, as shown by electrophoresis and the the theta(222)/theta(208) ratio. Our results indicate that SDS efficiently induces leucine zipper dimer dissociation with the monomers still partially folded. The experimental results provide important evidence for the previous model that partial helix formation precedes dimerization in coiled coil folding.

Unfolding and inactivation of fatty acid synthase from chicken liver during urea denaturation

The inactivation and conformational changes of the multifunctional fatty acid synthase (acyl-CoA:malonyl-CoA C-acyltransferase (decarboxylating, oxoacyl- and enoyl-reducing and thioester-hydrolyzing), EC 2.3.1.85) from chicken liver have been studied in urea solution. The results show that complete inactivation of the fatty acid synthase occurs before obvious conformational changes with regard to the overall, beta-ketoacyl reduction and acetoacetyl-CoA reduction reactions. Significant conformational changes indicated by the changes of the intrinsic fluorescence emission and the circular dichroism spectra occurred at higher urea concentrations. The kinetic rate constants for the two phase inactivation and unfolding reactions were measured and semilogarithmic plots of the activity versus time gave curves which could be resolved into two straight lines, indicating that both the inactivation and unfolding processes consisted of fast and slow phases as a first-order reaction. The results from Lineweaver-Burk plots indicated that urea is a competitive inhibitor for acetyl-CoA and malonyl-CoA, with K(m) increasing with increasing urea concentrations. However, urea is a noncompetitive inhibitor for NADPH, the substrate of the overall reaction and beta-ketoacyl reduction reaction, and acetylacetate, the substrate of the beta-ketoacyl reduction reaction. Activation by low concentrations of urea was observed although this activation was only temporarily induced in an early stage of inactivation. The aggregation phenomenon of the fatty acid synthase in a certain concentration range of urea (3-4 M) was also observed during unfolding. This result shows that this multifunctional enzyme unfolds with competition with misfolding in the folding pathway. Comparison of inactivation and conformational changes of the enzyme as well as aggregation imply that unfolding intermediates may exist during urea denaturation. The possible unfolding pathway of fatty acid synthase is also discussed in this paper.

Structure of human muscle creatine kinase

The crystal structure of human muscle creatine kinase has been determined by the molecular-replacement method and refined at 3.5A resolution. The structures of both the monomer and the dimer closely resemble those of the other known structures in the creatine kinase family. Two types of dimers, one with a non-crystallographic twofold symmetry axis and the other with a crystallographic twofold symmetry axis, were found to exist simultaneously in the crystal. These dimers form an infinite "double-helix"-like structure along an unusual long crystallographic 3(1) axis.

Direct visualization of the movement of the monomeric axonal transport motor UNC-104 along neuronal processes in living Caenorhabditis elegans

The formation and function of axons depends on the microtubule-based transport of cellular components from their sites of synthesis in the neuronal cell body to their sites of utilization at the axon terminus. To directly visualize this axonal transport in a living organism, we constructed transgenic lines of Caenorhabditis elegans that express green fluorescent protein fused to the monomeric synaptic vesicle transport motor, UNC-104. This UNC-104:: GFP construct rescued the Unc-104 mutant phenotype and was expressed throughout the nervous system. Using time-lapse confocal fluorescence microscopy, we were able to visualize fluorescent motor proteins moving in both directions along neuronal processes, some of which were identified definitely as axons and others as dendrites. Using kymograph analysis, we followed the movement of >900 particles. Most of them moved in one direction, but not necessarily at the same velocity. Ten percent of the observed particles reversed direction of movement during the period of observation, and 10% exhibited periods of movement interspersed with pauses. During episodes of persistent movement, particles moved at an average velocity of 1.02 microm/sec, which is close to the in vitro velocity of microtubule gliding driven by purified monomeric kinesin at high motor density. To our knowledge, this is the first direct visualization and analysis of the movement of specifically labeled microtubule motor proteins along axons in vivo.

Effect of two conserved amino acid residues on DREB1A function

Transcription factors of the DREBP subgroup and the EREBP subgroup contain conserved DNA-binding domains called AP2/EREBP domains, which specifically bind to DRE cis-element and GCC-box, respectively. The 14th and 19th amino acid residues of AP2/EREBP domains are absolutely conserved in the transcription factors of the DREBP subgroup as well as in the EREBP subgroup. However, these two residues of transcription factors of the DREBP subgroup are different from those of the EREBP subgroup. To assess the functional significance of these two residues in binding to the target sequence, the Val (14th residue) and Glu (19th residue) of the AP2/EREBP domain of DREB1A (a transcription factor of the DREBP subgroup) were mutated individually or doubly to Ala and Asp, respectively. This made the 14th and 19th amino acid residues of mutant DREB1A identical to the corresponding residues of transcription factors of the EREBP subgroup. Yeast in vivo analysis showed that: 1) on a selective medium plate of SD/His- Ura- Trp- + 30 mM approximately 60 mM 3-AT, the growth of yeast cells containing HIS and lacZ double reporter genes was normal in the transformation of the 19th singly mutated DREB1A, obviously inhibited in the transformation of the 14th singly mutated DREB1A, and seriously inhibited in the transformation of the 14th/19th doubly mutated DREB1A; 2) quantitative assay of beta-galactosidase activity showed that the intensities of lacZ expression decreased in the transformations of the 14th singly mutated and 14th/19th doubly mutated types. The experimental results revealed that the 19th site mutation did not affect the binding of the DREB1A transcription factor to the DRE cis-element; the 14th site mutation obviously inhibited their binding; and the double mutation of the 14th/19th sites seriously inhibited their binding. This suggests that the conserved Val (14th) and Glu (19th) residues are crucial in the regulation of the binding activity of DREB1A to the DRE cis-element.

[Estimates of breeding value of Inner Mongolia cashmere goats using animal model BLUP method]

In this study, single trait animal model of best linear unbiased prediction (BLUP) procedures was used to obtain estimates of 3,981 Inner Mongolia cashmere goats' breeding value for body weight and cashmere yield. The data were collected during 1989-1998 at Arbas cashmere goats farm, Etuoke banner, Inner Mongolia. Multiple traits of BLUP were used to get estimates of total breeding values (TBV) of all goats. The model included age and sex-herd-year as fixed effects, and individual additive effect and individual permanent environment as random effects. The selection based on breeding value and phenotypic value was compared. The results showed as following: (1) There was a large difference between weaning weight selection and TBV selection of ram lamb; (2) The difference between phenotypic selection and TBV selection of gimmer hogg reached a significant level (P < 0.01); (3) The difference between phenotypic selection and TBV selection of ram hogg reached a significant level (P < 0.01); (4) Rank correlation between body weight selection and body weight' EBV selection and that between cashmere yield selection and cashmere yield' EBV selection were not significant (P > 0.05). The study concluded precision of individual phenotypic selection was low and animal model BLUP was suitable to select Inner Mongolia cashmere goats. At last, this study gave a series of methods of selecting sires based on objective reality.

Aggregation of creatine kinase during refolding and chaperonin-mediated folding of creatine kinase

The course of refolding and reactivation of urea-denatured creatine kinase (ATP; creatine N-phosphotransferase, EC 2.7.3.2) has been studied in the absence and presence of molecular chaperonin GroEL. The enzyme was denatured in Tris--HCl buffer containing 6 M urea for 1 h. In the refolding studies, the denatured enzyme was diluted 60-fold into the same buffer containing GroEL or not for activity, turbidity, fluorescence measurements and polyacrylamide gel electrophoresis. The results show that the reactivation process is dependent of creatine kinase concentration in the concentration range 2.5--4 microM. The levels of activity recovery decrease with increasing enzyme concentration because of the formation of wrong aggregates. The molecular chaperonin GroEL can bind the refolding intermediate of creatine kinase and thus prevent the formation of wrong aggregates. This intermediate is an inactive dimeric form that is in a conformation resembling the 'molten globule' state.

Inhibition kinetics of green crab (Scylla serrata) alkaline phosphatase by zinc ions: a new type of complexing inhibition

The Tsou method was used to study the kinetic course of inactivation of green crab alkaline phosphatase by zinc ions. The results show that the enzyme was inactivated by a complexing scheme which has not been previously identified. The enzyme first reversibly and quickly binds Zn(2+) and then undergoes a slow reversible course to inactivation and slow conformational change. The inactivation reaction is a single molecule reaction and the apparent inactivation rate constant is for a saturated reaction being independent of Zn(2+) concentration if the concentration is sufficiently high. The microscopic rate constants of inactivation and the association constant were determined from the measurements.

Reactivation and refolding of rabbit muscle creatine kinase denatured in 2,2,2-trifluoroethanol solutions

The unfolding and refolding of creatine kinase (ATP:creatine N-phosphotransferase (CK), EC 2.7.3.2) during denaturation and reactivation by trifluoroethanol (TFE) have been studied. Significant aggregation was observed when CK was denatured at TFE concentrations between 10% and 40% (v/v). 50% TFE (v/v) was used to study the denaturation and unfolding of CK. The activity loss of CK was a very quick process, as was the marked conformational changes during denaturation followed by fluorescence emission spectra and far-ultraviolet CD spectra. DTNB modification and size exclusion chromatography were used to find that CK dissociated and was in its monomer state after denaturation with 50% TFE. Reactivation and refolding were observed after 80-fold dilution of the denatured CK into 0.05 M Tris-HCl buffer, pH 8.0. The denatured CK recovered about 38% activity following a two phase course (k(1)=4.82+/-0.41x10(-3) s(-1), k(2)=0.60+/-0.01x10(-3) s(-1)). Intrinsic fluorescence maximum intensity changes showed that the refolding process also followed biphasic kinetics (k(1)=4.34+/-0.27x10(-3) s(-1), k(2)=0.76+/-0.02x10(-3) s(-1)) after dilution into the proper solutions. The far-ultraviolet CD spectra ellipticity changes at 222 nm during the refolding process also showed a two phase course (k(1)=4.50+/-0.07x10(-3) s(-1), k(2)=1.13+/-0.05x10(-3) s(-1)). Our results suggest that TFE can be used as a reversible denaturant like urea and GuHCl. The 50% TFE induced CK denaturation state, which was referred to as the 'TFE state', and the partially refolded CK are compared with the molten globule state. The aggregation caused by TFE during denaturation is also discussed in this paper.

Two-phase unfolding pathway of ribonuclease A during denaturation induced by dithiothreitol

The dynamics of the unfolding process of bovine pancreatic ribonuclease A (RNase A) unfolded by dithiothreitol (DTT) at a low concentration of 1:30 were investigated in alkaline phosphate-buffered saline solutions at 303K and 313K by using proton nuclear magnetic resonance ((1)H NMR) spectra. Three NMR spectral parameters including Shannon entropy, mutual information, and correlation coefficient were introduced into the analysis. The results show that the unfolding process of RNase A was slowed to the order of many hours, and the kinetics of the unfolding pathway described by the three parameters is best fit by a model of two consecutive first-order reactions. Temperature greatly influences the rate constants of the unfolding kinetics with different temperature effects observed for the fast and the slow processes. The consistencies and the differences between the three sets of parameters show that they reflect the same relative denaturation pathway but different spectra windows of the unfolding process of RNase A. The results suggest that the unfolding process of RNase A induced by low concentrations of DTT is a two-phase pathway containing fast and slow first-order reactions.

Overexpression of plasminogen activator inhibitor type 2 in basal keratinocytes enhances papilloma formation in transgenic mice

The serpin plasminogen activator inhibitor (PAI) type 2 is expressed in differentiated epidermal keratinocytes. To explore its role in this tissue, we studied the impact of PAI-2 overexpression on epidermal differentiation and skin carcinogenesis. A mouse PAI-2-encoding transgene was targeted to basal epidermis and hair follicles under the control of the bovine keratin type 5 gene promoter. Two mouse lines were established, one of which strongly expressed the transgene and produced elevated levels of PAI-2 in the epidermis. Although it had no manifest impact on cellularity or differentiation of skin or hair follicles, PAI-2 overexpression rendered the mice highly susceptible to skin carcinogenesis induced by a single application of 7,12-dimethylbenz(a)anthracene (initiation) followed by twice weekly applications of 12-O-tetradecanoylphorbol-13-acetate [TPA (promotion)]. In transgenic mice, papillomas could be observed after 3 weeks of promotion; after 8 weeks, 94% (31 of 33) of transgenic mice had developed readily visible papillomas, whereas only 35% (7 of 20) of control mice (transgene-negative littermates) had barely detectable lesions. After 11 weeks, all but 1 (32 of 33) of the transgenic mice had papillomas as compared with only 65% (13 of 20) of control mice. After 11 weeks of promotion, application of TPA was terminated. In control mice, papillomas regressed and eventually disappeared; in transgenic mice, there was continued growth of papillomas, some of which further progressed to carcinomas. In contrast to massive apoptosis in regressing papillomas of control mice, only a few apoptotic cells were detected in transgenic papillomas after the cessation of TPA application. The effect of PAI-2 on papilloma formation did not appear to involve inhibition of the secreted protease urokinase-type plasminogen activator (uPA): PAI-2 accumulated predominantly in cells, and PAI-2 overexpression failed to alleviate a phenotype induced by uPA secretion, as demonstrated by a double transgenic strategy. In addition, in situ hybridization revealed that uPA mRNA is not expressed concomitantly with PAI-2 in developing papillomas. We conclude that overexpression of PAI-2 promotes the development and progression of epidermal papillomas in a manner that does not involve inhibition of its extracellular target protease, uPA, but appears to be related to an inhibition of apoptosis.

Reactivation kinetics of guanidine hydrochloride-denatured creatine kinase measured using the substrate reaction

Guanidine hydrochloride-denatured creatine kinase (CK) can very quickly form a dimer with reactivity when the denaturant is diluted into the reaction system in the presence of DTT or EDTA. Tsou's method and its applied equation [Tsou (1988), Adv. Enzymol. Rel. Areas Mol. Biol. 61, 381-436; Yang and Zhou (1998), Biochim. Biophys. Acta 1388, 190-198] were used to measure the kinetic reactivation rate constants and the reactivation degree for reassociated CK dimers. Partial reactivation (about 50% at best) occurred following a monophasic course during the substrate reaction when compared with previous time interval measurements. The reactivation degree increased with increasing DTT (0.1-5 mM) and EDTA (0.1-1 mM) concentrations. The apparent forward rate constants do not change with concentration, showing that the reactivation is a reversible first-order reaction, but not of complex formation type. However, the apparent forward rate constants do change with EDTA concentration, showing that the reactivation with EDTA is a reversible first-order reaction as well as of complex formation type. Excess DTT concentrations have an inhibitory effect, indicating that the excessive EDTA acts as a metal chealate not only for free Mg2+, but also for MgATP during the enzyme catalysis. This study shows that additional information about the reactivation of CK can be obtained from examining the substrate reaction. The possible refolding pathway of CK is discussed.

Effect of zinc ions on conformational stability of yeast alcohol dehydrogenase

Yeast alcohol dehydrogenase preparations were prepared with the conformational zinc ion removed (Apo-I YADH) and with both the conformational and catalytic zinc ions removed (Apo-II YADH). The unfolding of Apo-I YADH and Apo-II YADH during denaturation in urea solutions was then followed by fluorescence emission, circular dichroism, and second-derivative optical spectroscopies. Compared with the native enzyme, Apo-I YADH incurred some slight unfolding, and its stability against urea was markedly decreased, while Apo-II YADH incurred marked unfolding but contained residual ordered structure even at high urea concentrations. The results show that native YADH is more conformationally stable against urea denaturation than Apo-I YADH, indicating that the conformational Zn(2+) plays an important role in stabilizing the conformation of the YADH molecule. However, unfolding of the region around the conformational zinc ion is shown not to be the rate limited step in the unfolding of the molecule by the fact that the unfolding and inactivation rate constants of native and Apo-I YADH are the same. It is suggested that the catalytic zinc ion is more important in maintaining the structure of YADH. YADH lost its cooperative unfolding ability after the zinc ions were removed. The shape of the transition curves of Apo-I YADH suggests the existence of an unfolding intermediate. For both native and Apo-I YADH, inactivation occurs at much lower urea concentrations than that needed to produce significant conformational changes of the enzyme molecule. At urea concentration above 4 M, the inactivation rate constants are much higher than those of the fast phase of the reaction of unfolding. These results support the suggestion of flexibility at the active site of the enzyme (C. L. Tsou (1986) Trends Biochem. Sci., 11, 427-429; (1993) Science, 262, 308-381).

Effects of oxodiperoxovanadate (V) complexes on the activity of green crab (Scylla serrata) alkaline phosphatase

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme that catalyzes the nonspecific hydrolysis of phosphate monoesters. The effects of some pollutants in seawater on the activity of the enzyme will result in the loss of the biological function of the enzyme, which will affect the exuviating crab shell and threaten the survival of the animal. In the present paper, the effects of four oxodiperoxovanadate (V) complexes on the activity of green crab alkaline phosphatase have been studied. The results show that these vanadate derivatives can lead to reversible inactivation. The equilibrium constants for binding of inhibitors with the enzyme and/or the enzyme-substrate complexes have been determined. The results show that sodium (2,2;-bipyridine)oxodiperoxovanadate, pV(bipy), and potassium oxodiperoxo-(1,10-phenanthroline)vanadate, pV(phen), are competitive inhibitors, while potassium picolinato-oxodiperoxo-vanadate, pV(pic), and oxalato-oxodiperoxovanadate, pV(ox), are mixed-type inhibitors. These results suggest that pV(bipy) is a considerably more potent competitive inhibitor than pV(phen) and that the competitive inhibition effect of pV(pic) is stronger than that of pV(ox), but the non-competitive inhibition effect of pV(ox) is stronger than that of pV(pic).

Effects of zinc on creatine kinase: activity changes, conformational changes, and aggregation

The effects of zinc on creatine kinase (CK) are very distinctive compared with other bivalent metal ions. Zinc up to 0.1 mM induced increases in CK activity, accompanied by significant hydrophobic surface exposure and increase in alpha-helix content of CK. Zinc over 0.1 mM denatured and inactived CK. In the presence of 0.1 mM zinc, the CK activity was very close to that of the native CK, but its conformation changed greatly. The kinetic courses of CK inactivation and conformational change in the presence of 1 mM zinc were measured to determine apparent rate constants of inactivation and conformational change. Zinc over 0.05 mM induced CK aggregation at 37 degrees C, and the aggregation was dependent on zinc concentration, CK concentration, and temperature. The inactivation and aggregation can be reversed by EDTA. An explanation for CK aggregation induced by zinc is proposed, as well as a mechanism for CK abnormality in Alzheimer's disease.

Urokinase-type plasminogen activator and its receptor synergize to promote pathogenic proteolysis

Urokinase-type plasminogen activator (uPA) is a potent catalyst of extracellular proteolysis, which also binds to a high-affinity plasma membrane receptor (uPAR). Binding of uPA may influence pericellular proteolysis and/or activate intracellular signal transduction. Transgenic mice overexpressing either uPA or uPAR in basal epidermis and hair follicles had no detectable cutaneous alterations. In contrast, bi-transgenic mice overexpressing both uPA and uPAR, obtained by crossing the two transgenic lines, developed extensive alopecia induced by involution of hair follicles, epidermal thickening and sub-epidermal blisters. The phenotype was due to uPA catalytic activity since combined overexpression of uPAR and uPAR-binding but catalytically inactive uPA in the same tissue was not detrimental in another bi-transgenic line. It was accompanied by increased plasmin-generating capacity, up-regulation and activation of matrix metalloproteinases type-2 and -9, and cleavage of uPAR. Thus, combined overexpression of uPA and uPAR acts in synergy to promote pathogenic extracellular proteolysis.