[Evaluation of the application value of seven tumor-associated autoantibodies in non-small cell lung cancer based on machine learning algorithms].

Objective: Based on the diagnostic model established and validated by the machine learning algorithm, to investigate the value of seven tumor-associated autoantibodies (TAABs), namely anti-p53, PGP9.5, SOX2, GAGE7, GBU4-5, MAGEA1 and CAGE antibodies in the diagnosis of non-small cell lung cancer (NSCLC) and to differentiate between NSCLC and benign lung nodules. Methods: This was a retrospective study of clinical cases. Model building queue: a total of 227 primary patients who underwent radical lung cancer surgery in the Department of Thoracic Surgery, Shengjing Hospital of China Medical University, from November 2018 to June 2021 were collected as the NSCLC group, and 120 cases of benign lung nodules, 122 cases of pneumonia and 120 healthy individuals were selected as the control groups. External validation queue: a total of 100 primary patients who underwent radical lung cancer surgery in the Department of Thoracic Surgery, Shengjing Hospital of China Medical University, from May 2022 to December 2022 were collected as the NSCLC group, and 36 cases of benign lung nodules, 32 cases of pneumonia and 44 healthy individuals were selected as the control groups. In addition, NSCLC was divided into early (stage 0-ⅠB) and mid-to-late (stage ⅡA-ⅢB) subgroups. The levels of 7-TAABs were detected by enzyme immunoassay, and serum concentrations of CEA and CYFRA21-1 were detected by electrochemiluminescence. Four machine learning algorithms, XGBoost, Lasso logistic regression, Naïve Bayes, and Support Vector Machine are used to establish classification models. And the best performance model was chosen based on evaluation metrics and a multi-indicator combination model was established. In addition, an online risk evaluation tool was generated to assist clinical applications. Results: Except for p53, the levels of rest six TAABs, CEA and CYFRA21-1 were significantly higher in the NSCLC group (P<0.05). Serum levels of anti-SOX2 [1.50 (0.60, 10.85) U/ml vs. 0.8 (0.20, 2.10) U/ml, Z=2.630, P<0.05] and MAGEA1 antibodies [0.20 (0.10, 0.43) U/ml vs. 0.10 (0.10, 0.20) U/ml, Z=2.289, P<0.05], CEA [3.13 (2.12, 5.64) ng/ml vs. 2.11 (1.25, 3.09) ng/ml, Z=3.970, P<0.05] and CYFRA21-1 [4.31(2.37, 7.14) ng/ml vs. 2.53(1.92, 3.48) ng/ml, Z=3.959, P<0.05] were significantly higher in patients with mid-to late-stage NSCLC than in early stages. XGBoost model was used to establish a multi-indicator combined detection model (after removing p53). 6-TAABs combined with CYFRA21-1 was the best combination model for the diagnosis of NSCLC and early NSCLC. The optimal diagnostic thresholds were 0.410, 0.701 and 0.744, and the AUC was 0.828, 0.757 and 0.741, respectively (NSCLC vs. control, NSCLC vs. benign lung nodules, early NSCLC vs. benign lung nodules) in model building queue, and the AUC was 0.760, 0.710 and 0.660, respectively (NSCLC vs. control, NSCLC vs. benign lung nodules, early NSCLC vs. benign lung nodules) in external validation queue. Conclusion: In the diagnosis of NSCLC, 6-TAABs is superior to that of traditional tumor markers CEA and CYFRA21-1, and can compensate for the shortcomings of traditional tumor markers. For the differential diagnosis of NSCLC and benign lung nodule, "6-TAABs+CYFRA21-1" is the most cost-effective combination, and plays an important role in prevention and screening for early lung cancer.

[Genetic variants, circulating levels of monocyte chemoattractant protein-1 with risk of breast cancer: a case-control study and Mendelian randomization analysis].

Objective: To assess the association of genetic polymorphisms and circulating levels of chemokine monocyte chemoattractant protein-1 (MCP1) with risk of breast cancer. Methods: A total of 820 patients with pathologically confirmed breast cancer and 900 age-and area-of-residence-matched healthy controls who visited the hospital for routine health screening during the same period were included in this case-control study. Mendelian randomization analysis was performed using three widely followed functional single nucleotide polymorphisms (SNPs) of the MCP1 gene rs1024611, rs2857656 and rs4586 to construct instrumental variables. Results: MCP1 rs1024611 (OR=1.26, P=0.002), rs2857656 (OR=1.23, P=0.006) and rs4586 (OR=1.23, P=0.003) were significantly associated with increased risk of breast cancer. SNP rs1024611 (ß=1.194, P<0.001), rs2857656 (ß=1.221, P<0.001) and rs4586 (ß=1.137, P<0.001) were positively correlated with higher circulating level of MCP1. The case-control study showed that an increase of 23.7 pg/ml of circulating levels of MCP1 was associated with a 0.25-fold increased risk of breast cancer. MR analysis confirmed that the genetic predicted circulating levels of MCP1 were associated with an increased risk of breast cancer, and the risk of breast cancer increased by 0.20 times with an increase of 23.7 pg/ml in MCP1. Conclusion: Genetic variants and circulating levels of MCP1 are significantly associated with the risk of breast cancer and can be used as a biomarker for early prediction of breast cancer.

[25-hydroxyvitamin D, sex hormone levels and cardiovascular risk among men in northeast area of Henan province].

Objective: To examine associations of 25-hydroxyvitamin D [25(OH)D] concentrations with sex hormone levels and cardiovascular risk factors. Methods: A total of 697 male subjects were obtained from the thyroid disorders, lodine status and diabetes: a national epidemiological survey-2014 (TIDE) research--Henan sub-center survey through multistage stratified cluster random sampling from December 2015 to March 2016. The associations between 25(OH)D and sex hormones or cardiovascular risk factors were analyzed by linear regression analyses. Results: The age of the subjects was (46.6±15.9) years (19-85 years). Proportions of vitamin D deficient, vitamin D intermediate and vitamin D optimal were 9.3%, 13.1% and 77.6%, respectively. More subjects with vitamin D deficient were in urban area than in rural area (13.3% vs. 5.7%, P=0.001). After fully adjusting for age, residence area, economic status, education, body mass index, waist circumference, homeostasis model assessment of insulin resistance (HOMA-IR), hypertension, diabetes, triglyceride, high-density lipoproteincholesterol, total cholesterol, low-density lipoprotein cholesterol and uric acid, linear regression analyses showed that every 25 nmol/L increase in 25(OH)D levels increased lg FT(FT=free testosterone) by 0.013ng/L (ß=0.013, P=0.036), lg DHT (DHT=dihydrotestosterone) by 0.030 ng/L (ß=0.030, P=0.019), and lg AD (AD=androstenedione) by 0.019 µg/L (ß=0.019, P=0.008). After fully adjusting for age, residence area, economic status and education, every 25 nmol/L increase in 25(OH)D levels lowered glycosylated hemoglobin A1c (HbA1c) by 0.051% (ß=-0.051, P=0.027). Conclusions: Higher 25(OH)D concentrations in men were associated with higher FT, DHT, AD and lower HbA1c levels.

[Circulating tumor cells in patients with breast tumors were detected by a novel device: a multicenter, clinical trial in China].

Objective: Circulating tumor cells (CTC) have become an important part of liquid biopsy, which have underwent a process from simple counting to molecular typing and genotyping. To this end, we used Cellcollector to verify the effectiveness and safety of CTC detection in patients with breast tumor, and to conduct the following analysis. Methods: One hundred and ninety patients who received treatment in six leading Chinese cancer centers were involved from April to August in 2016. Among which, 127 patients were diagnosed as metastatic breast cancer, and the other 63 patients as benign breast tumors. Results: In metastatic breast cancer group, 74.8%(95/127) were CTC positive. While in benign tumor group, they were all CTC negative patients. The area under the Receiver Operating Characteristic curve were 0.832(95%CI: 0.784-0.879). The sensitivity of Cellcollector was 74.8%, specificity was 100% (Youden index 0.748). A total of 117 patients in MBC groups received a second detection of Cellcollector after 3-4 weeks, among which 44.4% (52/117) were CTC positive patients. The incidence of adverse events and severe adverse events in MBC was 66.9%(85/127) and 39.8% (53/127). Furthermore, we used Cellcollector to perform the HER2 testing and gene sequencing. Conclusions:In vivo isolation of CTCs overcomes blood volume limitations compared to other approaches. The further application of molecular typing and gene typing might help to implement CTC-based "liquid biopsies" into clinical decision making.

[Relationship between microsatellite instability and hepatocyte growth factor expression and their prognostic significance in colorectal cancer].

OBJECTIVE: To investigate the expression of hepatocyte growth factor (HGF) and its relationship with microsatellite instability (MSI) and their influence on survival in patients with colorectal cancer. METHODS: Immunohistochemistry (IHC) was used to detect the expression of HGF and MSI in 98 specimens of colorectal cancer. Tumors lacking protein expression of any of the four mismatch repair genes (MLH1, PMS2, MSH2 or MSH6) were labelled as MSI, and the rest were considered as microsatellite stable (MSS). The associations between expression and clinicopathological factors were assessed using Chi-square tests. Kaplan-Meier curves, log-rank test, and Cox regression were used to analyze the association between biomarker expressions and overall survival. RESULTS: The incidence rate of MSI in 98 colorectal specimens was 32.7%, and was statistically significantly correlated with the location of tumor and differentiation degree (P<0.05). The HGF-expression rate was 71.4%. The patients with an MSI tumor had a significantly higher HGF expression, compared with the patients with an MSS tumor (P=0.048). The 5-year survival rate of MSI group and MSS group were 39.8% and 58.7%, respectively (P=0.009). The 5-year survival rate of HGF-positive group and HGF-negative group were 46.2% and 67.9% (P=0.035). The multivariate analysis showed that lymphocytic infiltration, TMN stage, MSI and HGF are independent prognostic factors in colorectal cancer (P<0.05 for all). CONCLUSIONS: HGF is highly expressed in colorectal cancer patients with microsatellite instability. Both microsatellite instability and HGF are independent factors affecting the prognosis in patient with colorectal cancer.

Serum C-reactive protein predicts poor prognosis in patients with locoregionally advanced nasopharyngeal carcinoma treated with chemoradiotherapy.

BACKGROUND: We aimed to evaluate the association of serum C-reactive protein (crp) with prognosis in patients with locoregionally advanced nasopharyngeal carcinoma treated with chemoradiotherapy. METHODS: We retrospectively reviewed 79 patients with locoregionally advanced nasopharyngeal carcinoma (cT3-4N0-3M0) treated with chemoradiotherapy. Chemoradiotherapy consisted of external-beam radiotherapy to the nasopharynx (70-80 Gy), the lymph node-positive area (60-70 Gy), and the lymph node-negative area (50-60 Gy) combined with 3 cycles of various platinum-based regimens delivered at 3-week intervals. Elevated crp was defined as more than 8 mg/L. The survival rate was calculated using the Kaplan-Meier method, and univariate and multivariate analyses (Cox proportional hazards model) were used to identify factors significantly associated with prognosis. RESULTS: During the median follow-up of 3.9 years (range: 1-5.5 years), 23 patients died from nasopharyngeal cancer. The 5-year cancer-specific survival (css) rate was 62.90%. Before chemoradiotherapy, 18 patients had high serum crp; the css rate in that subgroup was significantly worse than the rate in the remaining patients (p = 0.0002). Multivariate analysis showed that crp was an independent prognostic indicator of css, with a hazard ratio of 3.04 (95% confidence interval: 1.22 to 7.55; p = 0.017). Among the 18 patients with elevated serum crp, 9 achieved normal serum crp after chemoradiotherapy, of whom 5 remained living with no evidence of recurrence or metastasis during follow-up. By contrast, the remaining 9 patients in whom serum crp did not normalize after chemoradiotherapy died within 4.2 years. CONCLUSIONS: Elevated serum crp before treatment predicts poor prognosis in patients with locoregionally advanced nasopharyngeal carcinoma treated with chemoradiotherapy.

Organophosphate esters in soils of Beijing urban parks: Occurrence, potential sources, and probabilistic health risks.

Organophosphate esters (OPEs) are an emerging contaminant widely distributed in the soil. OPEs have drawn increasing attention for their biological toxicity and possible threat to human health. This research investigated the pollution characteristics of two typical OPEs, organophosphate triesters (tri-OPEs) and organophosphate diesters (di-OPEs), in soils of 104 urban parks in Beijing. The median concentrations of Σ11tri-OPEs and Σ8di-OPEs were 157 and 17.9 ng/g dw, respectively. Tris(2-chloroisopropyl) phosphate and bis(2-ethylhexyl) phosphate were the dominant tri-OPE and di-OPE, respectively. Consumer materials (such as building insulation and decorative materials), traffic emissions, and reclaimed water irrigation may be critical sources of tri-OPEs in urban park soils. Di-OPEs mainly originated from the degradation of parent compounds and industrial applications. Machine learning models were employed to determine the influencing factors of OPEs and predict changes in their concentrations. The predicted OPEs concentrations in Beijing urban park soils in 2025 and 2030 are three times and five times those in 2018, respectively. According to probabilistic health risk assessment, non-carcinogenic and carcinogenic risks of OPEs can be negligible for children and adults. Our results could inform measures for preventing and controlling OPEs pollution in urban park soils.

CXCL12/CXCR4 Mediates Orthodontic Root Resorption via Regulating the M1/M2 Ratio.

Mechanical force-induced external root resorption is a major clinical side effect of orthodontic treatment. Recent work has revealed that M1 macrophages play a vital role in promoting orthodontic root resorption (ORR), but the mechanism of how mechanical force stimulation increases the M1/M2 macrophage ratio in periodontal tissue is poorly understood. In the current study, we showed that C-X-C motif chemokine 12 (CXCL12)+ periodontal ligament cells (PDLCs) and C-X-C chemokine receptor type 4 (CXCR4)+ monocytes in the periodontal ligament (PDL) were significantly increased after force application with ongoing root resorption, and these effects were partially rescued after force removal in mice. The expression of CXCL12 in PDLCs was increased by force stimulation in a time- and intensity-dependent manner in vitro. Blockage of the CXCL12/CXCR4 axis using CXCR4 antagonist AMD3100 was sufficient to alleviate ORR and reverse the force-enhanced M1/M2 macrophage ratio. Further mechanism exploration showed that Ly6Chi inflammatory monocytes homed in a CXCL12/CXCR4 axis-dependent manner. The number and proportion of CD11b+ Ly6Chi inflammatory monocytes in cervical lymph nodes were significantly increased by force loading, accompanied by decreased CD11b+ Ly6Chi monocytes in the blood. These changes were blunted by intraperitoneal injection of AMD3100. In addition, blockage of the CXCL12/CXCR4 axis effectively reversed M2 suppression and promoted M1 polarization. Collectively, results indicate that force-induced CXCL12/CXCR4 axis mediates ORR by increasing the M1/M2 ratio in periodontal tissues through attracting Ly6Chi inflammatory monocytes and modulating macrophage polarization. The results also imply that AMD3100 is potentially inhibitory to root resorption.

European earwig (Forficula auricularia) as a novel host for the entomopathogenic nematode Steinernema carpocapsae.

The natural history of many entomopathogenic nematode species remains unknown, despite their wide commercial availability as biological control agents. The ambushing entomopathogenic nematode, Steinernema carpocapsae, and the introduced European earwig, Forficula auricularia, forage on the soil surface. Since they likely encounter one another in nature, we hypothesized that earwigs are susceptible to nematode infection. In the laboratory, the LC(50) for F. auricularia was 226 S. carpocapsae/earwig and the reproductive potential was 123.5 infective juvenile nematodes/mg tissue. This susceptibility depended on host body size with significantly higher mortality rates seen in larger earwigs. In a study of host recognition behavior, S. carpocapsae infective juveniles responded to earwig cuticle as strongly as they did to Galleria mellonella cuticle. We also found that earwigs exposed to S. carpocapsae cleaned and scratched their front, middle and back legs significantly more than controls. Coupled with previous field data, these findings lead us to suggest that F. auricularia may be a potential host for S. carpocapsae.

[The expressions and correlations of IL-10, CD14 and CD68 in laryngal squamous cell carcinoma].

Objective:The aim of this study is to investigate the distribution of IL-10, CD14 and CD68 in the tumor microenvironment of LSCC with the clinicopathologic factors. Method:We detected the expressions of IL-10, CD14 and CD68 in 46 primary LSCC tumor tissues by immunohistochemistry staining and explore the relationship between them and clinicopathologic factors. Result:We found that the expressions of IL-10, CD14 and CD68 were significantly correlated with clinical stage and T stage (P<0.01). IL-10 and CD14 were correlated with lymph node metastasis (P<0.01), and CD68 was correlated with pathological differentiation (P<0.05). There is a positive correlation trend between the expression of IL-10 and CD14 (P<0.01). Conclusion:We confirm that the high level expressions of IL-10, monocytes and TAMs contribute to the tumor development of LSCC and there is a positive correlation between the expression of IL-10 and monocytes.

Radiation-enhancing effect of sodium glycididazole in patients suffering from non-small cell lung cancer with multiple brain metastases: A randomized, placebo-controlled study.

PURPOSE: Median survival of patients with brain metastases from non-small cell lung cancer is poor. This study was to investigate the radiation-enhancing effect of sodium glycididazole combined with whole-brain radiotherapy of multiple brain metastases from non-small cell lung cancer. PATIENTS AND METHODS: Sixty-four patients with multiple brain metastases from non-small cell lung cancer were included: the study group (n=32) received whole-brain radiotherapy combined with sodium glycididazole at a dose of 700mg/m(2) intravenous infusion 30minutes before radiotherapy, three times a week; the control group (n=32) only received whole-brain radiotherapy. The primary end point was central nervous system (CNS) progression-free survival and overall survival. The treatment-related toxicity was also recorded. RESULTS: The CNS disease control rate was better (90.6% vs 65.6%, P=0.016) in the study group than in the control group at 3 month of follow-up. The median CNS progression-free survival time was longer in the study group than in the control group (7.0 months vs 4.0 months, P=0.038). There was no significant difference of the median overall survival time between the study group and the control group (11.0 months vs 9.0 months, P=0.418). On the other hand, the treatment-related toxicity showed no statistically significant difference between these two groups (P>0.05). CONCLUSIONS: The study indicated that sodium glycididazole was an effective, promising radiation-enhancing agent that improved CNS disease control rate, extended the median CNS progression-free survival time and was well tolerated in patients suffering from non-small cell lung cancer with multiple brain metastases.

Modification of bovine heart mitochondrial transhydrogenase with tetranitromethane.

Modification of pyridine dinucleotide transhydrogenase with tetranitromethane resulted in inhibition of its activity. Development of a membrane potential in submitochondrial particles during the reduction of 3-acetylpyridine adenine dinucleotide (AcPyAD+) by NADPH decreased to nearly the same extent as the transhydrogenase rate on tetranitromethane treatment of the membrane. Kinetics of the inactivation of homogeneous transhydrogenase and the enzyme reconstituted into phosphatidylcholine liposomes indicate that a single essential residue was modified per active monomer. NADP+, NADPH and NADH gave substantial protection against tetranitromethane inactivation of both the nonenergy-linked and energy-linked transhydrogenase reactions of submitochondrial particles and the NADPH leads to AcPyAD+ reaction of reconstituted enzyme. NAD+ had no effect on inactivation. Tetranitromethane modification of reconstituted transhydrogenase resulted in a decrease in the rate of coupled H+ translocation that was comparable to the decrease in the rate of NADPH leads to AcPyAD+ transhydrogenation. It is concluded that tetranitromethane modification controls the H+ translocation process solely through its effect on catalytic activity, rather than through alteration of a separate H+-binding domain. Nitrotyrosine was not found in tetranitromethane-treated transhydrogenase. Both 5,5'-dithiobis(2-nitrobenzoate)-accessible and buried sulfhydryl groups were modified with tetranitromethane. NADH and NADPH prevented sulfhydryl reactivity toward tetranitromethane. These data indicate that the inhibition seen with tetranitromethane results from the modification of a cysteine residue.

Structure of 2-hydroxy-5-nitrobenzylated carboxypeptidase A.

Bovine pancreatic carboxypeptidase A (EC 3.4.12.2) was treated with dimethyl (2-hydroxy-5-nitrobenzyl)sulfonium chloride at pH 7.5, resulting in a preparation which consisted primarily of a monohydroxynitrobenzylated derivative of the enzyme. Samples of the hydroxynitrobenzylated enzyme were subjected to tryptic digestion and to cyanogen bromide cleavage, and resulting peptides were isolated chromatographically. One tryptic hydroxynitrobenzyl-containing peptide was isolated; its amino acid composition was that of the N-terminal tryptic segment of carboxypeptidase Agamma (residues 8--35). Likewise, CNBr cleavage of the hydroxynitrobenzylated enzyme revealed that the hydroxynitrobenzyl group resided in the N-terminal fragment, FN (residues 8--22). Neither of these hydroxynitrobenzylated peptides contains Trp, the amino acid residue which is characteristically the site of hydroxynitrobenzylation in proteins, and each was found to contain approximately one less Asx than the corresponding native peptide. Both dansylation and automated Edman degradation procedures revealed that the N-terminal Asn of carboxypeptidase Agamma had been modified by hydroxynitrobenzylation of the enzyme. Thus the sulfonium salt reacts with carboxypeptidase A in the same manner as that established earlier for 2-hydroxy-5-nitrobenzyl bromide (Radhakrishnan, T.M., Bradshaw, R.A., Deranleau, D.A. and Neurath, H. (1970) FEBS Lett. 7, 72--76). Such reactivity of the alpha-amino group presumably reflects its unique location with respect to Trp residues in the tertiary structure of the enzyme.

Defect in formation of functional matrix vesicles by growth plate chondrocytes in avian tibial dyschondroplasia: evidence of defective tissue vascularization.

Avian tibial dyschondroplasia (ATD), a disease characterized by an almost total lack of mineralization in affected areas of growth plate cartilage, may involve defective matrix vesicle (MV) mineralization. To explore the biochemical defect in ATD, both normal and diseased tissue were analyzed for the amount of isolatable MVs, their chemical composition, and their ability to induce mineral formation. We found significantly fewer MVs in ATD tissue, and in contrast to normal MVs, which rapidly mineralized when incubated in synthetic cartilage lymph, those isolated from ATD lesions induced only limited mineralization even after prolonged incubation. Analysis by detergent extraction revealed a nearly dysfunctional nucleational core in ATD MVs. Thus, in ATD tissue, there is a defect in the formation of MVs, and those that form are nearly inactive. There were also alterations in the lipid-dependent Ca2+(-)binding proteins (annexins) in ATD MVs. There were lower levels of annexins II and VI in endogenously produced collagenase-released matrix vesicles (CRMVs), but not in matrix vesicle-enriched microsomes (MVEMs) produced by tissue homogenization. These findings indicate that there is insufficient Ca2+ in ATD cells to enable incorporation of the annexins into MVs. Finally, there was evidence of phospholipid breakdown in ATD MVs, as well as in ATD tissue generally. This indicated that the ATD lesions were becoming necrotic. Taken together, these findings indicate that there is a defect in tissue vascularization such that the supply of mineral ions and nutrients to ATD cartilage is inadequate to support normal MV formation and subsequent mineralization.

Thyroid hormone inhibits growth and stimulates terminal differentiation of epiphyseal growth plate chondrocytes.

As a continuation of our studies on mineralization in epiphyseal growth plate (GP) chondrocyte cultures, the effects of tri-iodothyronine (T3) in both beta-glycerophosphate-containing, serum-free (HL-1) and beta-glycerophosphate-free, serum-containing medium (DATP5) were studied. The GP cells responded to T3 in a serum-, stage-, and dosage-dependent manner. Added at graded levels (0.1-10.0 nM) to preconfluent cultures (from day 7) in both HL-1 and DATP5, T3 caused progressive decreases in protein, collagen, and DNA synthesis but increased mineral deposition. In postconfluent cultures, these effects of T3 were generally muted. In preconfluent cultures, proteoglycan (PG) levels were not significantly affected in DATP5, although in HL-1 they were decreased by approximately 50%. In postconfluent cultures, T3 increased PG levels in DATP5 but had no effect in HL-1. In HL-1, alkaline phosphatase (ALP) activity was progressively increased by 200-500% in both pre- and postconfluent cultures. In DATP5 in preconfluent cultures, T3 initially stimulated but later suppressed ALP; in postconfluent cultures, T3 also transiently increased ALP but did not suppress activity upon longer exposure. The inhibitory effects of T3 on protein, PG, and DNA levels of GP chondrocytes suggest that in vivo its effects on bone growth must occur primarily after cellular proliferation. Apparently by binding to the 50 kDa thyroxine-binding globulin, which cannot penetrate the PG barrier, accessibility of T3 to GP chondrocytes is limited until the time of vascular penetration when its stimulatory effects on ALP and mineral deposition become critical for continued bone development.

Effects of calcitonin and parathyroid hormone on calcification of primary cultures of chicken growth plate chondrocytes.

Few studies have been directed toward elucidating the action of calcitonin (CT) and parathyroid hormone (PTH) on growth plate chondrocytes, cells directly involved in longitudinal bone growth and provisional calcification. In this study, primary cultures of avian growth plate chondrocytes that calcify without the supplement of beta-glycerophosphate were used to investigate the effects of synthetic human CT and 1-34 bovine PTH on (1) cell division and growth; (2) the deposition of Ca2+ and inorganic phosphate (Pi); (3) the activity of alkaline phosphatase (AP), an enzyme long associated with the mineralization process; (4) the levels of proteoglycans; and (5) the synthesis of collagens. Added continually to preconfluent cultures from day 6 until harvest, CT (1-30 nM) and PTH (0.1-1.0 nM) increased mineral deposition; the maximal increase was seen between days 18-21 at 10 nM CT (175-260%) and 0.5 nM PTH (approximately 170-280%), both p < 0.001. CT had no significant effect on cellular protein, or AP-specific activity, whereas PTH increased cellular protein, DNA, proteoglycan, and collagen content of the cultures in a dosage-dependent manner. AP activity and levels of Type II and X collagens and fibronectin in the culture medium showed a biphasic response to PTH; maximal increases were seen at 0.5 nM between days 15-18. Longer exposure (days 21-27) to PTH at higher levels (5-10 nM) caused a marked decreased in AP activity but a lesser decrease in the collagens. These results indicate that CT and PTH can act directly on chondrocytes to stimulate mineralization, but that PTH specifically stimulated cell division and synthesis of cellular and extracellular proteins by growth plate chondrocytes. The implications of these findings with regard to Ca2+ homeostasis and bone formation are discussed.

Establishment of the primary structure of the major lipid-dependent Ca2+ binding proteins of chicken growth plate cartilage matrix vesicles: identity with anchorin CII (annexin V) and annexin II.

Electron microscopic studies of calcifying vertebrate tissues reveal the locus of de novo mineral formation within matrix vesicles (MV). The direct involvement of MV in the initiation of mineral formation is supported by the fact that MV isolated from avian growth plate cartilage rapidly accumulate large amounts of Ca2+ and P(i) and induce mineral formation. Exploration of the constituents of MV has revealed two major protein components, a 33 and a 36 kD protein, the former of which binds to cartilage-specific collagens. These annexin-like proteins bind to acidic phospholipids in the presence of submicromolar levels of Ca2+. Antibodies raised against both the purified 33 and the 36 kD MV annexin do not cross-react with the other, indicating that they are distinct proteins. Reported here are studies elucidating the primary structure of both MV proteins using both conventional protein and molecular biologic methods. These studies establish that the 33 kD protein is nearly identical to anchorin CII (annexin V) and that the 36 kD protein is identical to avian annexin II. Immunolocalization studies show that hypertrophic chondrocytes at the calcification front of avian growth plate contain the highest level of these annexins. Further, immunogold labeling indicates that the annexins are localized within MV isolated from the growth plate. Recent studies indicate that annexin V is a new type of ion-selective Ca2+ channel protein that possesses selective collagen binding properties. Since MV are tightly associated with the collagen- and proteoglycan-rich matrix, it is tempting to speculate that this MV protein may be a component of stretch-activated ion channels that enhance Ca2+ uptake during mechanical stress.

The influence of trace elements on calcium phosphate formation by matrix vesicles.

The effects of two inhibitors, fluoride (F-) and zinc (Zn2+), were studied on the formation of mineral by matrix vesicles (MV) in an in vitro system. Kinetically, mineral formation by MV incubated in a synthetic cartilage lymph (SCL) is characterized by three phases: a lag period, a period of rapid uptake, and finally a period of slow uptake. Zn2+ at > or = 5 microM completely inhibited MV mineralization; at < or = 1 microM, it had little effect on rate of ion uptake, but delayed conversion of an OCP-like intermediate into hydroxyapatite (OHAp). F- at > or = 10 microM reduced the rate of rapid uptake by MV and caused the OCP-like precursor to convert to OHAp. When synthetic OCP was seeded into SCL, mineralization ensued and OHAp became the dominant phase. With Zn2+ present, OCP-like features persisted longer; with F-, the OCP-like features were lost more rapidly. When ACP was seeded into SCL, OHAp formed; Zn2+ at < or = 1 microM caused OCP-like mineral to form. Our findings indicate that Zn2+ stabilizes a noncrystalline precursor in MV regulating the length of the lag period; Zn2+ also favors the formation of an OCP-like intermediate whose growth accounts for the rapid uptake phase. This OCP-like phase appears to nucleate formation of OHAp by MV.