Insulin-like growth factor (IGF) and hepatocyte growth factor (HGF) in follicular fluid cooperatively promote the oncogenesis of high-grade serous carcinoma from fallopian tube epithelial cells: Dissection of the molecular effects

Incessant ovulation is believed to be a potential cause of epithelial ovarian cancer (EOC). Our previous investigations have shown that insulin-like growth factor (IGF2) and hepatocyte growth factor (HGF) in the ovulatory follicular fluid (FF) contributed to the malignant transformation initiated by p53 mutations. Here we examined the individual and synergistic impacts of IGF2 and HGF on enhancing the malignant properties of high-grade serous carcinoma (HGSC), the most aggressive type of EOC, and its precursor lesion, serous tubal intraepithelial carcinoma (STIC). In a mouse xenograft co-injection model, we observed that FF co-injection induced tumorigenesis of STIC-mimicking cells, FE25. Co-injection with IGF2 or HGF partially recapitulated the tumorigenic effects of FF, but co-injection with both resulted in a higher tumorigenic rate than FF. We analyzed the different transformation phenotypes influenced by these FF growth signals through receptor inhibition. The IGF signal was necessary for clonogenicity, while the HGF signal played a crucial role in the migration and invasion of STIC and HGSC cells. Both signals were necessary for the malignant phenotype of anchoring-independent growth but had little impact on cell proliferation. The downstream signals responsible for these HGF activities were identified as the tyrosine-protein kinase Met (cMET)/mitogen-activated protein kinase and cMET/AKT pathways. Together with the previous finding that the FF-IGF2 could mediate clonogenicity and stemness activities via the IGF-1R/AKT/mammalian target of rapamycin and IGF-1R/AKT/NANOG pathways, respectively, this study demonstrated the cooperation of the FF-sourced IGF and HGF growth signals in the malignant transformation and progression of HGSC through both common and distinct signaling pathways. These findings help develop targeted prevention of HGSC.

Successful Live Twin Birth through IVF/ICSI from a Couple with an Infertile Father with Pericentric Inversion of Chromosome 9 (p12q13): A Case with a High Aneuploidy Rate

Evidence suggests that the pericentric inversion of chromosome 9 (inv(9)) does not affect the aneuploidy rate (38.5%) after IVF. Herein, we report a successful live female twin birth through IVF/ICSI with a high aneuploidy rate from a couple within which the infertile father has inv(9)(p12q13). A couple (a 34-year-old male and a 35-year-old female) was referred to our clinic due to infertility. The wife has a child with her previous husband. Results from the infertility workup of both parents were normal. Karyotyping revealed that the inv(9)(p12q13) of the father was the only cytogenetic abnormality. Preimplantation genetic testing for aneuploidies (PGT-A) after IVF/ICSI revealed a high aneuploidy rate (77%; 10/13). Two euploid blastocysts were transferred, resulting in a successful live female twin birth. The presented case highlights the possibility that inv(9)(p12q13) in males may impact the fertility and euploidy rate. PGT-A facilitates the selection of qualified blastocysts for the optimization of live-birth outcomes.

Insuline-Like Growth Factor-2 (IGF2) and Hepatocyte Growth Factor (HGF) Promote Lymphomagenesis in p53-null Mice in Tissue-specific and Estrogen-signaling Dependent Manners

Background: Trp53^-/- mice are prone to develop lymphomas at old ages. Factors promoting this tumorigenesis are unknown. Here, we showed human ovulatory follicular fluid (FF) largely promotes lymphomagenesis in Trp53^-/- mice at earlier ages. Meanwhile, we clarified that IGF2 and HGF are important cell transforming factors within FF. Methods: To induce tumor formation, 5% FFs, 100 ng/ml IGF2, 20 ng/ml HGF, or both IGF2 and HGF in a volume of 200 µl PBS, was injected into 8-wk-old female Trp53 ^-/- mice at the mammary fat pad. The injection was repeated weekly for up to 7 weeks or extending to 13 weeks to observe the accumulative incidence of lymphomagenesis. Immunohistochemistry staining and gene rearrangement analysis were used to identify the tumor type. Results: By injecting FF into the mammary fat pad weekly, lymphomas developed in 8/16 (50%) of mice by seven weeks. We identified IGF2 and HGF in FF is largely responsible for this activity. The same weekly injection of IGF2, HGF, and their combination induced lymphomas in 4/11 (36%), 3/8 (38%), and 6/9 (67%) mice, respectively. Interestingly, tumorigenesis was induced only when those were injected into the adipose tissues in the mammary gland, but not when injected into non-adipose sites. We also found this tumor-promoting activity is estradiol (E2)-dependent and relies on estrogen receptor (ER) α expression in the adipose stroma. No tumor or only tiny tumor was yielded when the ovaries were resected or when ER is antagonized. Finally, an extension of the weekly FF-injection to 13 weeks did not further increase the lymphomagenesis rate, suggesting an effect on pre-initiated cancer cells. Conclusions: Taken together, the study disclosed a robust tumor-promoting effect of IGF2 and HGF in the p53 loss-initiated lymphomagenesis depending on an adipose microenvironment in the presence of E2. In light of the clarity of this spontaneous tumor promotion model, we provide a new tool for studying p53-mediated lymphomagenesis and suggest that, as a chemoprevention test, this is a practical model to perform.

Low-Voltage Metal-Oxide Thin Film Transistors Using P-Type Tin-Oxide Semiconductors

In this paper, the effect of channel annealing and oxygen flow rate in P-type tin-monoxide (SnO) thin film transistor (TFT) was investigated to reach the process compatibility with n-type oxide-based TFT. The optimized P-type SnO TFT with a small threshold voltage of -0.1 V, a high field-effect mobility of 4 cm² V^-1 s^-1 and an on/off current ratio of >10² was proposed. From the experimental results, the 150 °C channel annealing revealed a metallic behavior but a semiconductor-like property at a higher 200 °C that was favorable for transistor rectification. Besides, the higher oxygen flow rate was also helpful for improving device mobility and driving current, but shows a slight increase in off-state leakage, which is unavoidable due to the increase of grain in SnO channel.

IGF-axis confers transformation and regeneration of fallopian tube fimbria epithelium upon ovulation

Background

The fallopian tube fimbria is regarded as the main tissue of origin and incessant ovulation as the main risk factor of ovarian high-grade serous carcinoma. Previously, we discovered the tumorigenesis activity of human ovulatory follicular fluid (FF) upon injection to the mammary fat pad of Trp53-null mice. We also found a mutagenesis activity of FF-ROS and a apoptosis-rescuing activity of Hb from retrograde menstruation. However, neither of them can explain the tumorigenesis activities of FF.

Methods

From two cohorts of ovulatory FF retrieved from IVF patients, the main growth factor responsible for the transformation of human fimbrial epithelial cells was identified. Mechanism of activation, ways of signal transduction of the growth factor, as well as the cellular and genetic phenotypes of the malignant transformation was characterized.

Findings

In this study, we showed that insulin-like growth factor (IGF)-axis proteins, including IGFBP-bound IGF2 as well as the IGFBP-lytic enzyme PAPP-A, are abundantly present in FF. Upon engaging with glycosaminoglycans on the membrane of fimbrial epithelial cells, PAPP-A cleaves IGFBPs and releases IGF2 to bind with IGF-1R. Through the IGF-1R/AKT/mTOR and IGF-1R/AKT/NANOG pathways, FF-IGF leads to stemness and survival, and in the case of TP53/Rb or TP53/CCNE1 loss, to clonal expansion and malignant transformation of fimbrial epithelial cells. By depleting each IGF axis component from FF, we proved that IGF2, IGFBP2/6, and PAPP-A are all essential and confer the majority of the transformation and regeneration activities.

Interpretation

This study revealed that the FF–IGF axis functions to regenerate tissue damage after ovulation and promote the transformation of fimbrial epithelial cells that have been initiated by p53- and Rb-pathway disruptions.

Fund

The study was supported by grants of the Ministry of Science and Technology, Taiwan (MOST 106-2314-B-303-001-MY2; MOST 105-2314-B-303-017-MY2; MOST 107-2314-B-303-013-MY3), and Buddhist Tzu Chi General Hospital, Taiwan (TCMMP104-04-01).

Trends of Opportunistic Salpingectomy

Background and Objectives:

This study analyzed the trends of opportunistic salpingectomy (OS) accompanied by hysterectomy in a 9-year follow-up period at a single institute.

Methods:

This retrospective cohort study included 1184 women at Hualien Tzu Chi Hospital from 2007 to 2015 who underwent hysterectomy performed with or without OS. Parameters including patient age, operating time, surgical approach, length of hospital stay, and perioperative complications were evaluated.

Results:

There was an increase in the number of hysterectomies with OS (from 8% to 80%; P < .001) over the study period. Minimal additional operating time was necessary for hysterectomy with OS (3.7 and 3.6 minutes in open and laparoscopic surgery, respectively). No significant differences were observed in the risks of hospital readmission or blood transfusions between women who underwent hysterectomy with OS performed with the open approach and those who underwent the procedure using the laparoscopic approach. From 2007 to 2015, the proportion of open hysterectomies decreased from 56% to 6%.

Conclusion:

The results of this 9-year follow-up study revealed that, as a cancer prevention method, OS seems to be feasible and safe, requires minimal extra time, and does not increase the morbidity or long-term sequelae.

Abstract B09: IGF axis plays a pivotal role in the ovulation-induced malignant transformation of fallopian tube fimbrial epithelial cells

Owing to uncertain tissue-of-origin and elusive etiology, high-grade serous ovarian carcinoma (HGSC) is typically diagnosed at late stages with poor prognosis. Recent studies have unveiled the fallopian tube fimbria as the major tissue of origin and incessant ovulation as the main etiology, but the mechanism of cancer initiation remains elusive. In a series of studies we have found a majority of preovulatory follicular fluids (FF) contain high level of ROS that induce DNA double-strand breaks as well as apoptosis to the fimbrial epithelial cells in vitro and in vivo. We also found that hemoglobin (Hb) in pelvis, most likely contributed by retrograde menstruation of previous cycles, reduces the ovulatory ROS level extracellularly and results in a shifting from the apoptotic to the survival fate of ROS-stressed fimbrial epithelial cells. These initiating factors in FF, although they may contribute to the TP53 mutation and other early genetic hits in the genesis of HGSC, cannot fully transform the immortalized fimbrial epithelial cell lines with loss of p53 and Rb. Here we show that IGF axis proteins, including IGFBP2- and IGFBP6-bound IGFs as well as the IGFBP-lytic enzyme PAPP-A, are abundant in ovulatory FF. Upon engaging with glycosaminoglycans (GAG) on the membrane of fimbrial epithelial cells, PAPP-A cleaves IGFBPs and releases bioactive IGF in close proximity to its receptor IGF-1R. Through the PI3K/Akt/mTOR signaling pathway, the FF-derived IGF exerts transformation effects on immortalized fimbrial epithelial cells, inducing anchorage independent growth and xenograft tumorigenesis. By contrast, much less transformation was noted when IGFBP2/6 or PAPP-A was depleted from the FF, when the GAG-docking was blocked, or when IGF-1R ormTOR was inhibited. Taken together, the serial studies have unveiled multiple cancer initiating factors in ovulation and retrograde menstruation where ROS acts as the mutagen, hemoglobin serves as the surviving rescuer, and the IGF axis acts as the main transforming signal.

Citation Format: Tang-Yuan Chu, Hsuan-Shun Huang, Che-Fang Hsu, Pao-Chu Chen. IGF axis plays a pivotal role in the ovulation-induced malignant transformation of fallopian tube fimbrial epithelial cells. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B09.

Haemoglobin in pelvic fluid rescues Fallopian tube epithelial cells from reactive oxygen species stress and apoptosis

Fallopian tube fimbrial epithelium is considered to be the major site of origin of ovarian high-grade serous carcinoma, with p53 loss being the earliest and universal change. We previously reported that reactive oxygen species (ROS) in the ovulatory follicular fluids (FFs) are mutagenic and cytotoxic to fimbrial epithelial cells, which are bathed in the peritoneal fluid mixed with FFs. Here, we observed that ferryl haemoglobin (Hb), which was abundantly present in ovulatory FFs and pelvic peritoneal fluids, could rescue p53-deficient immortalized fimbrial epithelial (FE25) cells and oviduct epithelial cells from Trp53-null mice from lethal ovulatory ROS stress. Ferryl Hb and FF containing high Hb levels protected FE25 cells from apoptosis, mainly by consuming extracellular ROS and reducing NADPH oxidase-mediated cell death. The remaining extracellular ROS could still induce DNA double-strand breaks in the fimbrial epithelial cells. Our study revealed that ferryl Hb in peritoneal fluid rescued ROS-stressed, DNA-damaged fimbrial epithelial cells from death, and suggested that peritoneal blood from various sources may contribute to the ovulation-induced transformation of Fallopian tube epithelium. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Platelet-Derived Growth Factor in the Ovarian Follicle Attracts the Stromal Cells of the Fallopian Tube Fimbriae

During human ovulation, the fallopian tube fimbriae must move to the ovulation site to catch the oocyte. As the tissue-of-origin of the majority of ovarian high-grade serous carcinoma (HGSC), the fallopian tube fimbriae carrying a precursor cancer lesion may also approach the ovulatory site for metastasis. We hypothesize that platelet-derived growth factor (PDGF) in mature follicle fluid (FF) attracts the migration of PDGFR-expressing fimbriae toward the ovulating follicle. We observed that more PDGFR-β was expressed in the distal part than in the proximal parts of the fallopian tube, particularly in stromal cells in the lamina propria. The stromal cells, but not the epithelial cells, from normal fimbriae and fallopian tube HGSC were highly chemotactic to mature FF. The chemotactic activities were positively correlated with PDGF-BB and estradiol levels in FF and were abolished by a blocking antibody of PDGFR-β and by tyrosine kinase inhibitor imatinib. When PDGF-BB/AB was depleted from the FF, more than 80% of chemotaxis activities were diminished. This study suggests an ovarian follicle-directed and PDGF-dependent attraction of fallopian tube fimbriae before ovulation. The same mechanism may also be crucial for the ovarian homing of HGSC, which largely originates in the fimbriae.

Prenatal air pollutant exposure and occurrence of atopic dermatitis

BACKGROUND

Hereditary and environmental factors have been related to the occurrence of atopic dermatitis (AD) in early childhood. However, the role of prenatal and early postnatal exposure to air pollutants has not been totally elucidated.

OBJECTIVES

To evaluate the association between prenatal air pollutant exposure and occurrence of AD.

METHODS

In total 24 200 infant-mother pairs were recruited to participate in the Taiwan Birth Cohort Study in 2005 using multistage stratified sampling. Medical history, including physician-diagnosed AD, was inquired by questionnaire at the infant's age of 6 months. Monthly averages of five criteria air pollutants - NO2 , CO, O3 , SO2 and PM10 - were retrieved from 66 air-quality-monitoring stations, and interpolated to all administrative districts using the kriging method. Exposure data during each of the three gestational trimesters and three months after birth were calculated for each study subject, and odds ratios (ORs) of AD occurrence were calculated by logistic regression.

RESULTS

Among the participants, 16 686 mother-infant pairs were qualified for and included in the analysis. Among them, 1206 infants (7·2%) had been diagnosed as having AD before the age of 6 months, and the prevalence was higher in boys (8·3%) than in girls (6·1%). The occurrence of AD was significantly associated with CO exposure during the whole gestational period [adjusted OR (aOR) 1·37, 95% confidence interval (CI) 1·06-1·78] and the first trimester (aOR 1·51, 95% CI 1·16-1·97). We did not observe any significant association among the other air pollutants during either the whole gestational period or any period of the three trimesters and 3 months after birth.

CONCLUSIONS

Our study found a relationship between AD occurrence and gestational exposure to CO, where exposure during the first trimester seemed to be the most important.

Mutagenic, surviving and tumorigenic effects of follicular fluid in the context of p53 loss: initiation of fimbria carcinogenesis

Ovulation is the strongest risk factor for ovarian high-grade serous carcinoma (HGSC) that largely originates from the fallopian tube fimbriae and always carries loss-of-function mutations of TP53 in both early and late lesions. Mature ovarian follicle contains high level of reactive oxygen species (ROS). When released from ovulation, follicular fluid (FF) bathes the fimbriae and may lead to DNA double-strand break (DSB) and neoplastic transformation. In this study, we examined the mutagenic and tumorigenic activities of human pre-ovulatory FFs. A subset (6/11) of FFs was found with high levels of ROS whereas the antioxidant capacities were indifferent. These ROS(high) FFs induced intracellular ROS and DSBs in the secretory cell population of fimbriae epithelium. When p53 and Rb were turned down, the FF-exposed secretory cells overcame apoptosis and expanded the population carrying ROS and DSB. The cancer initiation and promotion effects of FF were further recapitulated in Trp53 (-/-) mice. When introduced into the mammary fat pad, ROS(high) but not ROS(low) FFs induced early-onset B-cell lymphoma. Cotreatment with physiological concentration of melatonin, a potent antioxidant, ameliorated the mutagenic and tumorigenic effect of ROS(high) FF in vitro and in vivo. The study revealed ROS and mitogens in mature ovarian follicles could initiate the transformation of fimbria epithelium in the context of p53 loss and melatonin is a potent preventive agent.

The Role of Oxygen Vacancies on Switching Characteristics of TiO(x) Resistive Memories

Using oxygen vacancy rich (VO-rich) TiO(x) dielectric with high work function Ni electrode, large resistance window of > 10x and narrow current distribution were realized in the Ni/VO-rich TiO(x)/TaN resistive random access memory (RRAM) device. It can be ascribed to the formation and rupture of conducting filaments by the percolation of VOs and Ti interstitials. Moreover, the effects of annealing treatment and top electrode on resistive switching properties were investigated. The device with VO-deficient TiO(x) after annealing reduces the defects and exhibits small window and low switching currents. The device with low work function Ti top electrode provides low barrier to increase reset currents and the randomly distributed filamentary paths forms near the Ti causes wide current distribution.

White emission from non-planar InGaN/GaN MQW LEDs grown on GaN template with truncated hexagonal pyramids

Non-planar InGaN/GaN multiple quantum well (MQW) structures are grown on a GaN template with truncated hexagonal pyramids (THPs) featuring c-plane and r-plane surfaces. The THP array is formed by the regrowth of the GaN layer on a selective-area Si-implanted GaN template. Transmission electron microscopy shows that the InGaN/GaN epitaxial layers regrown on the THPs exhibit different growth rates and indium compositions of the InGaN layer between the c-plane and r-plane surfaces. Consequently, InGaN/GaN MQW light-emitting diodes grown on the GaN THP array emit multiple wavelengths approaching near white light.

Maternal employment and atopic dermatitis in children: a prospective cohort study

BACKGROUND

Considering the early onset of atopic dermatitis (AD), which most often arises in the first year of life, risk factors occurring very early in life must be considered. Little is known about the effects of maternal occupational exposure on the development of atopic disorders in children.

OBJECTIVES

The aim of this study was to evaluate associations between maternal employment and childhood AD.

METHODS

We used multistage stratified systematic sampling to recruit 24,200 mother-newborn pairs from the Taiwan national birth register. Information on maternal occupation categories, work stress, working time, shift work and potential confounders during pregnancy was gathered by questionnaires after birth. At 3 years of age, information on the development of AD was assessed by home interviews. Multiple logistic regression analysis was performed to estimate the association of maternal employment and AD.

RESULTS

Overall, 11,962 out of 19,381 mothers (61·7%) worked during pregnancy. The children of mothers who worked during pregnancy had an increased risk of AD compared with those whose mothers did not work [odds ratio (OR) 1·38, 95% confidence interval (CI) 1·25-1·53]. The children of mothers with a professional or technical occupation had a higher risk of AD (OR 1·64, 95% CI 1·44-1·87). The risk of AD was found to increase with maternal work stress during pregnancy in a dose-response manner (P(trend)<0·01). The mothers of children with AD had a longer working time than those without AD (P<0·0001). However, no significant association between AD and maternal shift work was found.

CONCLUSIONS

Working in professional or technical occupations increased the risk of childhood AD in addition to work stress during pregnancy.

Dual-wavelength GaN-based LEDs grown on truncated hexagonal pyramids formed by selective-area regrowth on Si-implanted GaN templates

GaN-based blue light-emitting diodes (LEDs) with micro truncated hexagonal pyramid (THP) array were grown on selective-area Si-implanted GaN (SIG) templates. The GaN epitaxial layer regrown on the SIG templates exhibited selective growth and subsequent lateral growth to form the THP array. The observed selective-area growth was attributed to the different crystal structures between the Si-implanted and implantation-free regions. Consequently, LEDs grown on the GaN THP array emitted broad electroluminescence spectra with multiple peaks. Spatially resolved cathodoluminescence revealed that the broad spectra originated from different areas within each THP. Transmission electron microscopy showed the GaN-based epitaxial layers, including InGaN/GaN multi-quantum wells regrown at different growth rates (or with different In content in the InGaN wells) between the semi-polar and c-face planes of each THP.

Blood trace minerals concentrations and oxidative stress in patients with obstructive sleep apnea

BACKGROUND

Obstructive sleep apnea (OSA) is associated with increased oxidative stress. Certain essential trace minerals have shown to play an important role in the maintenance of redox homeostasis. We determined the concentrations of trace minerals in OSA patients and assessed their relationships to OSA severity as indicated by the apnea/ hypopnea index (AHI).

METHODS

We enrolled 44 patients with newly diagnosed mild to moderate OSA and 20 without OSA. The following parameters were measured: polysomnographic values of nocturnal sleep; plasma trace minerals zinc (Zn), copper (Cu), iron (Fe), and erythrocyte selenium (Se); oxidative stress status; and plasma high-sensitivity C-reactive protein (hs-CRP) and tumor necrosis factor-α (TNF-α).

RESULTS

Compared to controls matched for age, gender, and body mass index, OSA patients had lower concentrations of plasma Zn and erythrocyte Se and higher plasma concentrations of Cu and Fe. OSA patients had significantly higher plasma concentrations of hs-CRP, TNF-α, and malondialdehyde (MDA), and lower erythrocyte antioxidant enzyme glutathione peroxidase (GPx) and superoxide dismutase activities. Significant differences in all the above parameters were also found in patients with moderate OSA compared to those with mild OSA. Furthermore, AHI values correlated significantly with neck circumference, GPx activity, and MDA, hs-CRP, and TNF-α concentrations in OSA patients. AHI values were also negatively associated with concentrations of plasma Zn and erythrocyte Se, but were positively linked to plasma concentrations of Fe and Cu.

CONCLUSIONS

Abnormal concentrations of these trace minerals may reflect oxidative damage and inflammatory response, thus increasing the severity of OSA.

Internal pudendal artery injury during prolapse surgery using nonanchored mesh

Herein is presented the case of a patient with stage 2 uterine prolapse treated surgically using nonanchored mesh. Complications were internal pudendal artery injury and a massive presacral hematoma that formed after surgery. Transcatheter arterial embolization was performed immediately, and the bleeding stopped. The patient subsequently experienced difficulty micturating and defecating because of presacral hematoma compression. Self-micturation and defecation capabilities were regained gradually at approximately 1 week after surgery. The hematoma resolved completely by 71 days postoperatively. Comprehensive knowledge of pelvic anatomy is important when performing surgery to treat prolapse using mesh kits. Removing the mesh and prophylactic antibiotic therapy is a means of conservatively managing a pelvic hematoma caused by prolapse surgery.

Effect of meniscus replacement fixation technique on restoration of knee contact mechanics and stability

The menisci are important biomechanical components of the knee. We developed and validated a finite element model of meniscal replacement to assess the effect of surgical fixation technique on contact behavior and knee stability. The geometry of femoral and tibial articular cartilage and menisci was segmented from magnetic resonance images of a normal cadaver knee using MIMICS (Materialise, Leuven, Belgium). A finite element mesh was generated using HyperWorks (Altair Inc, Santa Ana, CA). A finite element solver (Abaqus v6.9, Simulia, Providence, RI) was used to compute contact area and stresses under axial loading and to assess stability (reaction force generated during anteroposterior translation of the femur). The natural and surgical attachments of the meniscal horns and peripheral rim were simulated using springs. After total meniscectomy, femoral contact area decreased by 26% with a concomitant increase in average contact stresses (36%) and peak contact stresses (33%). Replacing the meniscus without suturing the horns did little to restore femoral contact area. Suturing the horns increased contact area and reduced peak contact stresses. Increasing suture stiffness correlated with increased meniscal contact stresses as a greater proportion of tibiofemoral load was transferred to the meniscus. A small incremental benefit was seen of simulated bone plug fixation over the suture construct with the highest stiffness (50 N/mm). Suturing the rim did little to change contact conditions. The nominal anteroposterior stiffness reduced by 3.1 N/mm after meniscectomy. In contrast to contact area and stress, stiffness of the horn fixation sutures had a smaller effect on anteroposterior stability. On the other hand suturing the rim of the meniscus affected anteroposterior stability to a much larger degree. This model emphasizes the importance of the meniscus in knee biomechanics. Appropriate meniscal replacement fixation techniques are likely to be critical to the clinical success of meniscal replacement. While contact conditions are mainly sensitive to meniscus horn fixation, the stability of the knee under anteroposterior shear loads appeared to be more sensitive to meniscal rim fixation. This model may also be useful in predicting the effect of biomaterial mechanical properties and meniscal replacement shape on knee contact conditions.

A nonlinear viscoelastic finite element model of polyethylene

A nonlinear viscoelastic finite element model of ultra-high molecular weight polyethylene (UHMWPE) was developed in this study. Eight cylindrical specimens were machined from ram extruded UHMWPE bar stock (GUR 1020) and tested under constant compression at 7% strain for 100 sec. The stress strain data during the initial ramp up to 7% strain was utilized to model the "instantaneous" stress-strain response using a Mooney-Rivlin material model. The viscoelastic behavior was modeled using the time-dependent relaxation in stress seen after the initial maximum stress was achieved using a stored energy formulation. A cylindrical model of similar dimensions was created using a finite element analysis software program. The cylinder was made up of hexahedral elements, which were given the material properties utilizing the "instantaneous" stress-strain curve and the energy-relaxation curve obtained from the experimental data. The cylinder was compressed between two flat rigid bodies that simulated the fixtures of the testing machine. Experimental stress-relaxation, creep and dynamic testing data were then used to validate the model. The mean error for predicted versus experimental data for stress relaxation at different strain levels was 4.2%. The mean error for the creep test was 7% and for dynamic test was 5.4%. Finally, dynamic loading in a hip arthroplasty was modeled and validated experimentally with an error of 8%. This study establishes a working finite element material model of UHMWPE that can be utilized to simulate a variety of postoperative arthroplasty conditions.

Filaggrin polymorphism P478S, IgE level, and atopic phenotypes

BACKGROUND

Whether environmental exposures may modulate the effect of the skin barrier gene on atopic dermatitis (AD) remains to be elucidated.

OBJECTIVES

To determine whether filaggrin (FLG) variants can serve as a predictor for atopic disorders in Chinese individuals and if allergen exposures may modify the effect of FLG variants on AD by total IgE levels.

METHODS

In total, 116 children aged 2-5years with AD and 212 control subjects were analysed for the FLG variants using DNA sequencing. Multiple logistic regression models were performed to estimate the association among FLG polymorphisms and atopic phenotypes. Serum total IgE level, standing for the degree of allergen exposures, was later stratified to determine the effects of FLG polymorphisms on AD.

RESULTS

A significant difference in genotype frequency was found among AD cases and controls in FLG P478S polymorphism. FLG P478S GG genotype significantly increased the risk of AD [odds ratio (OR) 4·60, 95% confidence interval (CI) 1·88-11·24]. In addition, among subjects with AD, GG genotypes also significantly increased the risk of developing asthma (OR 4·68, 95% CI 1·37-16·03). Further, a similar result was obtained for allergic rhinitis (OR 3·23, 95% CI 1·01-10·30). Interestingly, the P478S GG genotype was significantly related to AD (OR 5·67, 95% CI 1·93-16·60) in children with IgE level ≥100 kU L(-1) . However, the association was not evident when IgE level was < 100 kU L(-1) .

CONCLUSIONS

Our results suggest that the FLG P478S polymorphism may confer susceptibility to the development of AD among Chinese individuals and may be modified by IgE levels.

Glycogen synthase kinase-3β is a functional modulator of serotonin-1B receptors

Glycogen synthase kinase-3 (GSK3) is a constitutively active protein kinase that is involved in neuronal regulation and is a potential pharmacological target of neurological disorders. We found previously that GSK3β selectively interacts with 5-hydroxytryptamine-1B receptors (5-HT1BR) that have important functions in serotonin neurotransmission and behavior. In this study, we provide new information supporting the importance of GSK3β in 5-HT1BR-regulated signaling, physiological function, and behaviors. Using molecular, biochemical, pharmacological, and behavioral approaches, we tested 5-HT1BR's interaction with G(i)α(2) and β-arrestin2 and 5-HT1BR-regulated signaling in cells, serotonin release in mouse cerebral cortical slices, and behaviors in wild-type and β-arrestin2 knockout mice. Molecular ablation of GSK3β and GSK3 inhibitors abolished serotonin-induced change of 5-HT1BR coupling to G(i)α(2) and associated signaling but had no effect on serotonin-induced recruitment of β-arrestin2 to 5-HT1BR. This effect is specific for 5-HT1BR because GSK3 inhibitors did not change the interaction between serotonin 1A receptors and G(i)α(2). Two GSK3 inhibitors, N-(4-methoxybenzyl)-N'-(5-nitro-1,3-thiazol-2-yl)urea (AR-A014418) and 3-(5-bromo-1-methyl-1H-indol-3-yl)-4-(benzofuran-3-yl)pyrrole-2,5-dione (BIP-135), efficiently abolished the inhibitory effect of the 5-HT1BR agonist anpirtoline on serotonin release in mouse cerebral cortical slices. GSK3 inhibitors also facilitated the 5-HT1BR agonist anpirtoline-induced behavioral effect in the tail suspension test but spared anpirtoline-induced locomotor activity. These results suggest that GSK3β is a functional selective modulator of 5-HT1BR-regulated signaling, and GSK3 inhibitors fine-tune the physiological and behavioral actions of 5-HT1BR. Future studies may elucidate the significant roles of GSK3 in serotonin neurotransmission and implications of GSK3 inhibitors as functional selective modulators of 5-HT1BR.

Assessment of nematode community structure as a bioindicator in river monitoring

Nematode communities from river water and sediments were assessed for the abundance, feeding types, maturity indices and nematode channel ratio (NCR). The sampling sites studied included different levels of pollution and contamination from agricultural, industrial and sewage sources. The nematode abundance found in the sediment samples was more than that in the water samples. The lowest nematode abundance in sediment samples and the lowest NCR in water samples were both found at the industrial pollution site. Water samples showed positive correlation between the NCR and river pollution index (RPI). Mean maturity indices in sediment samples were inversely correlated with RPI. The pollutant source determined the relationship between NCR and pollution level, while maturity index always showed negative correlation with pollutant level regardless of the pollutant sources. The nematode abundance and its community structure were both reliable bioindicators for monitoring long-term river pollution in both qualitative and quantitative aspects.

The association of clinical findings and exposure profiles with melamine associated nephrolithiasis

BACKGROUND

Little is known about the exposure profiles of melamine in children. We evaluated the association of clinical findings, exposure patterns and biomarkers with nephrolithiasis in children with potential exposure to melamine.

METHODS

A case-control study was conducted in children aged 0-16 years with potential exposure to contaminated dairy products. Cases were defined as nephrolithiasis detected by renal ultrasonography. On the basis of different brands of contaminated dairy products consumed, subjects were classified into high exposure, low exposure and control groups with estimated melamine exposure levels of higher than 2.5 ppm, 0.05-2.5 ppm and lower than detection limits <0.05 ppm. We measured urine melamine for those with nephrolithiasis and age-matched and gender-matched controls within the subset of the study population.

RESULTS

The duration of consumption of contaminated products was longer in children with nephrolithiasis in the high exposure group than in controls (median (IQR) 12.0 (3.3-24.0) vs 6.0 (4.0-7.0) months; p = 0.048). High melamine exposure levels were significantly associated with nephrolithiasis (OR 61.04 (95% CI 12.73 to 292.84)). The risk was found to increase with estimate melamine exposure levels (p for trend <0.001). Two among 10 affected subjects with nephrolithiasis showed elevated urine melamine levels. In comparison, levels of all 20 controls were lower than the detection limit.

CONCLUSIONS

The risk of melamine-associated nephrolithiasis was related to duration of consumption of contaminated products and estimated melamine exposure levels. Though urine melamine was not a sensitive test, it might serve as an exposure biomarker in melamine-associated nephrolithiasis.

Differential effects of Usp14 and Uch-L1 on the ubiquitin proteasome system and synaptic activity

The ubiquitin proteasome pathway has been implicated in the pathogenesis of many neurodegenerative diseases, and alterations in two different deubiquitinating enzymes, Uch-L1 and Usp14, result in neurological phenotypes in mice. We identified a new mutation in Uch-L1 and compared the roles of Uch-L1 and Usp14 in the ubiquitin proteasome system. Deficiencies in either Uch-L1 or Usp14 result in decreased levels of ubiquitin, suggesting that they both regulate ubiquitin stability in the nervous system. However, the effect of ubiquitin depletion on viability and onset of symptoms is more severe in the Usp14-deficient mice, and changes in hippocampal synaptic transmission were only observed in Usp14-deficient mice. In addition, while Usp14 appears to function at the proteasome, Uch-L1 deficiency resulted in up-regulation of lysosomal components, indicating that Uch-L1 and Usp14 may differentially affect the ubiquitin proteasome system and synaptic activity by regulating different pools of ubiquitin in the cell.

Neuro-mediators as predictors of paediatric atopic dermatitis

BACKGROUND

Attempts to identify predictors of atopic dermatitis (AD) have focused on genetic and immunologic factors. However, the role of neuro-mediators remains to be elucidated.

OBJECTIVE

To evaluate nerve growth factor (NGF) and vaso-active intestinal peptide (VIP) in predicting paediatric AD and assess their correlation with intrinsic and extrinsic types of AD.

METHODS

We performed a nested case-control study in the prospective Taiwan birth panel cohort study. Cord and maternal plasma and questionnaires were gathered at birth. During follow-up, we identified 40 available AD cases, which were matched to 80 unaffected controls chosen from this cohort. The concentrations of IgE, NGF, and VIP in cord and maternal plasma of these subjects were performed by ELISA. Receiver-operating characteristic (ROC) curves were generated to see how well each biomarker could predict AD.

RESULTS

The NGF levels were significantly higher in AD patients than controls (mean+/-SD: 65.47+/-44.45 vs. 49.21+/-12.18 pg/mL for cord plasma and 89.68+/-41.04 vs. 66.96+/-23.05 pg/mL for maternal plasma) (P<0.05). VIP levels were also higher but not statistically significant. Plasma NGF may be a better biomarker than IgE in detecting paediatric AD (area under the ROC curve=0.65 vs. 0.61 for cord plasma and 0.69 vs. 0.61 for maternal plasma). Maternal NGF levels were significantly higher in patients with both intrinsic (96.18+/-48.15 pg/mL) and extrinsic (86.18+/-37.23 pg/mL) types of AD compared with controls (66.96+/-23.05 pg/mL) (P<0.05). We assessed a significant correlation between self-reported stress during pregnancy and maternal NGF levels (r=0.22, P=0.02).

CONCLUSION

Our results suggest that NGF is a good alternative biomarker in predicting children with a risk of AD.

Laparoscopic management of tubal ectopic pregnancy

OBJECTIVES

To study the surgical morbidity associated with laparoscopic management of tubal ectopic pregnancy compared with that of open laparotomy.

METHODS

A retrospective study in an academic tertiary obstetrics and gynecology referral center was conducted from 2005 through 2007. Forty-nine patients who had pathology-confirmed tubal ectopic pregnancies were divided into 2 groups, laparoscopy (n=38) and laparotomy (n=11). The main outcome measures included operative time, blood loss, and complications.

RESULTS

No significant differences existed in gestational age, beta-hCG level, history of previous surgeries, pelvic inflammatory disease, or endometriosis. The laparotomy group included more patients with a history of previous ectopic pregnancy. The length of hospital stay following laparoscopic management was significantly less than that in the laparotomy group.

CONCLUSION

Laparoscopic management of ectopic pregnancy can be the most beneficial procedure with maximum safety and efficacy.

Environmental risk factors for early infantile atopic dermatitis

Previous studies of predictors of atopic dermatitis (AD) in Asia have had limited sample size and small numbers of variables focused primarily on family history or dietary exposures. The purpose of this study was to evaluate the influence of various environmental risk factors for early infantile AD. We used multistage, stratified systematic sampling to recruit 2048 mother-child pairs from the Taiwan national birth registration in 2003. Information on environmental risk factors for infant AD gathered by questionnaire were available from 1760 infants at 6 months of age. Multiple logistic regression was used to estimate adjusted odds ratios (aORs) and their 95% confidence intervals (CIs) for risk factors for AD after adjusting for potential confounders. AD was noted in 118 of 1760 (6.7%) of the infants. After adjusting for maternal age and education, family history of atopy, infant gender, and gestational age, fungi on walls of the house [aOR 2.14 (95% CI 1.41-3.22)] and frequent use of microwave oven at home [aOR 1.71 (95% CI 1.13-2.58)] increased the risk of early infantile AD. This study suggests that environmental factors do play a role in early infantile AD. Fungi, a kind of aeroallergen, are especially important in humid climate as in Taiwan and their impacts might be felt at the early infant stage. The hazards of microwave use should be paid more attention.

Redox potential of tea infusion as an index for the degree of fermentation

Redox potential of tea infusion is suggested as an index for the extent of tea fermentation. The potential was measured between platinum and Ag/AgCl electrode pair with a voltmeter with high input impedance (>1000 Gohms). Phosphate buffer (10 mM, pH 7.0) was used to extract the infusion and served as the supporting electrolytes for the electrochemical measurement. The reliability (the Nernst's behavior) for redox potential measurement was verified with a standard redox couple, ferricyanide/ferrocyanide. Tentative interferences from dissolved oxygen and the major coexisting reducing chemical, ascorbate, were discussed. Redox potential showed strong correlation with the fermentation process during indoor withering process. Eleven kinds of tea with different fermentation extents including Sencha, Pilochun, Pouchong, Formosa oolong tea, Lipton green tea, Lipton black tea, and Taiwanese black tea were tested.

Heterogeneous Diazo-Transfer Reaction: A Facile Unmasking of Azide Groups on Amine-Functionalized Insoluble Supports for Solid-Phase Synthesis

Solid-supported azides are commonly generated through direct nucleophilic displacement of appropriately activated supports by the azide ion. This reaction usually proceeds rather sluggishly under harsh conditions. Here, we report that triflyl azide rapidly reacts with a series of amine-functionalized solid supports to generate azide-coated supports under mild conditions. Further, we demonstrate that the "azide coat" allows facile loading of alkyne-functionalized leader nucleoside monomers by click chemistry. Finally, we show that the nucleoside-functionalized supports are suitable for solid-phase oligonucleotide synthetic applications. The approach herein described extends the scope of the amine-azide conversion reaction and may be adaptable for the introduction of azide to diverse amine-terminated solid supports that are not easily accessible by the conventional nucleophilic displacement method.

Comparison of the severity of illness scoring systems for critically ill cirrhotic patients with renal failure

BACKGROUND

Mortality rates of cirrhotic patients with renal failure admitted to the medical intensive care unit (ICU) are high. End-stage liver disease is frequently complicated by disturbances of renal function. This investigation is aimed to compare the predicting ability of acute physiology, age, chronic health evaluation II and III (APACHE II and III), sequential organ failure assessment (SOFA), and Child-Pugh scoring systems, obtained on the first day of ICU admission, for hospital mortality in critically ill cirrhotic patients with renal failure.

METHODS

Sixty-seven patients with liver cirrhosis and renal failure were admitted to ICU from April 2001-March 2002. Information considered necessary for computing the Child-Pugh, SOFA, APACHE II and APACHE III score on the first day of ICU admission was prospectively collected.

RESULTS

The overall hospital mortality rate was 86.6%. Liver disease was most commonly attributed to hepatitis B viral infection. The development of renal failure was associated with a history of gastrointestinal bleeding. Goodness-of-fit was good for SOFA, APACHE II and APACHE III scores. The APACHE III and SOFA models reported good areas under receiver operating characteristic curve (0.878 +/- 0.050 and 0.868 +/- 0.051, respectively).

CONCLUSION

Renal failure is common in critically ill patients with cirrhosis. The prognosis for cirrhotic patients with renal failure is poor. APACHE III and SOFA showed excellent discrimination power in this group of patients. They are superior to APACHE II and Child-Pugh scores in this homogenous group of patients.

Multiple colonic ulcers caused by Churg-Strauss syndrome in a 15-year-old girl

Churg-Strauss syndrome (CSS), or allergic granulomatous angiitis, is an uncommon vasculitic syndrome that is found mainly in middle-aged adults. We describe a 15-year-old girl with CSS, diagnosed by histological findings and characteristic clinical features. The patient experienced two episodes of catastrophic gastrointestinal vasculitis, resulting in resection of 150 cm of small intestine and right hemicolectomy. Colonoscopic examination showed multiple colonic ulcers with active bleeding. The clinical course of the patient was grave and refractory to the therapy of steroid and cytotoxic drugs. In the world literature only two patients with multiple colonic ulcers caused by CSS have been reported, and very rare cases of childhood-onset CSS have been published. We reviewed CSS in children and found that the prognosis was poorer than that in adults.

Thymoma is associated with an increased risk of second malignancy

BACKGROUND

An association between thymoma and second malignancy has been suggested but has not been validated. Whether the relation is due to treatment or to other thymoma-associated conditions is unclear.

METHODS

The authors studied 192 consecutive patients with thymoma and compared the incidence of second malignancies with those of 206 patients who underwent thymectomy for nonthymomatous conditions and 1426 patients with nasopharyngeal carcinoma (NPC). Detailed clinicopathologic features of thymoma patients with second malignancies were described.

RESULTS

Additional malignancies were detected in 15 of 192 patients (8%) during their clinical courses. The risk for those patients was significantly greater compared with the risk for patients with nonthymomatous conditions (adjusted odds ratio [OR], 3.81; 95% confidential intervals [95%CI], 1.05-13.81; P = 0.042) and patients with NPC (adjusted OR, 4.89; 95%CI, 2.26-10.53; P < 0.0001) after adjustment for age, gender, length of follow-up, myasthenia gravis, and radiation therapy. The occurrence of second malignancies did not correlate with histologic type or stage of thymoma, radiation therapy, or myasthenia gravis.

CONCLUSIONS

Thymoma is associated with an increased risk of second malignancy. The association cannot be attributed to the effect of thymectomy or radiation therapy. Patients with thymoma, even if it is benign, should be followed regularly to facilitate the early detection of other malignancies.

Theoretical study of the internal rotational barriers in nitrotoluenes, nitrophenols, and nitroanilines

The molecular geometries and internal rotational barriers of the nitro group of 3-nitrotoluene (3-NT), 4-nitrotoluene (4-NT), 3-nitrophenol (3-NP), 4-nitrophenol (4-NP), 3-nitroaniline (3-NA), and 4-nitroaniline (4-NA) were calculated by five different types of density functional theory (DFT) methods with three different levels of basis sets. Analyses of the torsional angles of the nitro, methyl, amino, and hydroxyl groups indicate that 3-NP, and 4-NP are planar molecules, but 3-NT, 4-NT, 3-NA, and 4-NA are not planar molecules. Internal rotational barriers of the nitro group were calculated as the V2 barrier, and the NO2 torsional potentials for each molecule were given. The heights of the V2 barrier vary with the DFT methods, the basis sets, and the kinds and positions of substituents. The average values of the V2 barriers for 3-NT, 4-NT, 3-NP, 4-NP, 3-NA, and 4-NA are 6.44, 6.92, 6.64, 7.93, 6.38, and 9.13 kcal/mol, respectively. Torsional potentials of the OH and NH2 groups of nitrophenol and nitroaniline derivatives were also studied by a B3LYP/6-31G* approach. Except for the OH group in 2-NP, these derivatives have the V2 barrier.

Multimodal nonlinear spectral microscopy based on a femtosecond Cr:forsterite laser

We demonstrate a novel multimodal nonlinear spectral microscopy based on a femtosecond Cr:forsterite laser at 1230 nm. By acquiring the whole nonlinear spectrum in the visible and near-NIR region, this novel technique allows a combination of different imaging modalities, including second-harmonic generation, third-harmonic generation, and multiple-photon fluorescence. Combined with the selected excitation wavelength, which is located in the IR transparency window, this microscopic technique can provide high penetration depth with reduced damage and is ideal for studying living cells.

Polyethylene contact stresses, articular congruity, and knee alignment

Increased conformity at the tibiofemoral articulation increases contact area and reduces contact stresses in total knee arthroplasty. Malalignment, however, can increase polyethylene contact stresses. The effect of knee alignment and articular conformity on contact stresses was evaluated in a finite element model. The polyethylene insert and femoral component were modeled in high- and low-conformity conditions. An axial tibial load of 3000 N was applied across the tibiofemoral articulation at different knee positions ranging from 0 degrees, to 90 degrees, flexion, 0 to 10 mm anteroposterior translation, 0 degrees to 10 degrees axial rotation, and coronal plane angulation (liftoff). Increased conformity significantly reduced contact stresses in neutral alignment (by 44% at 0 degrees flexion and 36% at 60 degrees and 90 degrees flexion). Liftoff significantly increased contact stresses in low- and high-conformity conditions, but to a lesser degree in the high-conformity condition. Malalignment in rotation was most detrimental especially with the high-conformity insert design. Overall, increasing articular conformity reduced stresses when the knee was well-aligned. However, malalignment in axial rotation was detrimental. Mobile-bearing knee designs with increased articular congruity may result in lower contact stresses, especially the rotating-bearing designs that theoretically minimize rotational malalignment.

Polyethylene wear and variations in knee kinematics

A six-station knee wear simulator was used to test a posterior cruciate-retaining total knee arthroplasty design. Six implants each were tested in three groups; low intensity, high intensity, and malalignment using kinematic inputs from normal gait data, more severe loading conditions, and 3 degrees varus malalignment, respectively. For each group, gravimetric wear of the polyethylene inserts was measured for 5,000,000 cycles. Knee wear testing showed significantly different results for the three groups. Low intensity group inserts had mean wear rates of 3.1 (+/- 1.2) mg per million cycles. High intensity group inserts had significantly higher mean wear rates of 7.4 (+/- 2.7) mg per million cycles. Malalignment group inserts had the highest wear rates of 9.2 (+/- 3.3) mg per million cycles. The wear generated in the knee simulator seems to be dependent on the relative motions and loads at the articulating surface. The high intensity groups were subjected to motions that included reciprocating anteroposterior translations and a higher peak axial load than the low intensity group. This resulted in increasing the amount of wear. Varus malalignment also increased the total wear significantly. These results may explain some of the wide variations in wear seen in retrieved knee implants.

Thymoma is associated with an increased risk of second malignancy

BACKGROUND

An association between thymoma and second malignancy has been suggested but has not been validated. Whether the relation is due to treatment or to other thymoma-associated conditions is unclear.

METHODS

The authors studied 192 consecutive patients with thymoma and compared the incidence of second malignancies with those of 206 patients who underwent thymectomy for nonthymomatous conditions and 1426 patients with nasopharyngeal carcinoma (NPC). Detailed clinicopathologic features of thymoma patients with second malignancies were described.

RESULTS

Additional malignancies were detected in 15 of 192 patients (8%) during their clinical courses. The risk for those patients was significantly greater compared with the risk for patients with nonthymomatous conditions (adjusted odds ratio [OR], 3.81; 95% confidential intervals [95%CI], 1.05-13.81; P = 0.042) and patients with NPC (adjusted OR, 4.89; 95%CI, 2.26-10.53; P < 0.0001) after adjustment for age, gender, length of follow-up, myasthenia gravis, and radiation therapy. The occurrence of second malignancies did not correlate with histologic type or stage of thymoma, radiation therapy, or myasthenia gravis.

CONCLUSIONS

Thymoma is associated with an increased risk of second malignancy. The association cannot be attributed to the effect of thymectomy or radiation therapy. Patients with thymoma, even if it is benign, should be followed regularly to facilitate the early detection of other malignancies.

Human chondrocyte apoptosis in response to mechanical injury

OBJECTIVE

The effect of mechanical injury on chondrocyte viability and matrix degradation was studied. It was proposed that mechanical injury to human cartilage explants results in chondrocyte apoptosis with associated loss of glycosaminoglycans.

DESIGN

Full thickness human cartilage explants, 5 mm in diameter were subjected to a single static mechanical stress of 14 MPa for 500 ms under radially unconfined compression. Glycosaminoglycan (GAG) release and percentage of cells undergoing apoptosis were measured at 96 h after injury. To establish the time course of apoptosis, explants were subjected to 30% strain and cultured for varying intervals up to 7 days after injury. A group of loaded explants were also treated with the broad spectrum caspase inhibitor z-Vad.fmk after injury.

RESULTS

Internucleosomal DNA fragmentation as one indicator of apoptosis was observed in 34% (S.D.+/-11) of chondrocytes at 96 h in response to mechanical loading at 14 MPa, compared to 4% (S.D.+/-2) in the non-loaded explants. Evidence for cell death induction via apoptosis was also obtained by electron microscopy and caspase cleavage of cytokeratin. GAG release was also higher for the loaded explants, mean 1.9% (S.D.+/-0.14) of total GAG content, compared to control explants, mean 0.8% (S.D.+/-0.28). The percentage of apoptotic cells also correlated with the level of GAG release into the culture media. The percentage of apoptotic chondrocytes demonstrated a progressive increase from 6 h to 7 days post-injury. When loaded explants were cultured in z-Vad.fmk after injury, a 50% reduction in apoptosis rates was seen.

CONCLUSIONS

These results demonstrate that mechanical injury induces chondrocyte apoptosis and release of GAG from the matrix. The time course suggests that a therapeutic window may exist where apoptosis could be inhibited. This potentially identifies a new approach to chondroprotection.