Background: The biological properties of oxidized and non-oxidized PTH are substantially different. Oxidized PTH (oxPTH) loses its PTH receptor-stimulating properties, whereas non-oxidized PTH ...(n-oxPTH) is a full agonist of the receptor. This was described in more than 20 well published studies in the 1970s and 80s. However, PTH oxidation has been ignored during the development of PTH assays for clinical use so far. Even the nowadays used third generation assay systems do not consider oxidation of PTH We recently developed an assay to differentiate between oxPTH and n-oxPTH. In the current study we established normal values for this assay system. Furthermore, we compare the ratio of oxPTH to n-oxPTH in different population with chronic renal failure: 620 children with renal failure stage 2-4 of the 4C study, 342 adult patients on dialysis, and 602 kidney transplant recipients. In addition, we performed modeling of the interaction of either oxPTH or n-oxPTH with the PTH receptor using biophysical structure approaches. Results: The children had the highest mean as well as maximum n-oxPTH concentrations as compared to adult patients (both patients on dialysis as well as kidney transplant recipients). The relationship between oxPTH and n-oxPTH of individual patients varied substantially in all three populations with renal impairment. The analysis of n-oxPTH in 89 healthy control subjects revealed that n-oxPTH concentrations in patient with renal failure were higher as compared to healthy adult controls (2.25-fold in children with renal failure, 1.53-fold in adult patients on dialysis, and 1.56-fold in kidney transplant recipients, respectively). Computer assisted biophysical structure modeling demonstrated, however, minor sterical- and/or electrostatic changes in oxPTH and n-oxPTH. This indicated that PTH oxidation may induce refolding of PTH and hence alters PTH-PTH receptor interaction via oxidation induced three-dimensional structure alteration of PTH. Conclusion: A huge proportion of circulating PTH measured by current state-of-the-art assay systems is oxidized and thus not biologically active. The relationship between oxPTH and n-oxPTH of individual patients varied substantially. Non-oxidized PTH concentrations are 1.5 - 2.25 fold higher in patients with renal failure as compared to health controls. Measurements of n-oxPTH may reflect the hormone status more precise. The iPTH measures describes most likely oxidative stress in patients with renal failure rather than the PTH hormone status. This, however, needs to be demonstrated in further clinical studies.
The tight junction regulator zonulin has attracted clinical attention as a biomarker of increased gastrointestinal permeability. Recent work also suggests zonulin to represent a general regulator of ...tissue barriers and a player in metabolic inflammation. Here, we investigated the associations of zonulin with chronic heart failure (CHF), kidney function, and metabolic inflammation.
Using multiple linear regression (Generalized Linear Model), this study determined the association of plasma zonulin with different laboratory and clinical parameters in 225 patients carrying automatic implantable cardioverters/defibrillators (AICD) for primary or secondary prevention. In another 115 patients with diastolic or systolic CHF, we investigated a possible relationship between zonulin and CHF severity.
In the AICD cohort, zonulin associated inversely with serum creatinine (p = 0.013), carboxymethyl-lysine calprotectin (p < 0.001), and kynurenine (p = 0.009) and positively with homoarginine (p < 0.001). In the subgroup with type-2 diabetes (T2D) (n = 51), zonulin increased significantly with high-sensitivity CRP (p = 0.014). In the CHF cohort, we found a highly significant rise of NT-proBNP, but not of zonulin with NYHA functional classes I-IV or other parameters of CHF severity.
The inverse associations of zonulin with creatinine and markers of cardio-vascular risk (high CMLcalprotectin and kynurenine, low homoarginine) are novel findings that need further experimental and clinical clarification. Our study indicates zonulin involvement in metabolic inflammation in T2D, but no association with disease status in CHF.
Bone sialoprotein (BSP) is a noncollagenous bone matrix protein that is important for both mineralization and cell-cell interactions.
Tissue studies in primary breast cancers have shown that ...immunohistochemical expression of BSP is associated with a high incidence
of bone metastases in the course of the disease. We used a RIA to investigate the importance of serum BSP as a marker for
subsequent bone metastases. Between 1994 and 1996, preoperative blood samples were collected from 388 consecutive patients
with nonmetastatic breast cancer and from 30 control patients with benign breast disease. Serum BSP concentrations were measured
in a blinded fashion by RIA. The cutoff for elevated serum BSP values was 24 ng/ml, i.e. , two SDs above the normal mean value. Serum BSP was correlated with the risk of metastasis and analyzed with regard to its
prognostic value. After a median follow-up period of only 20 months, 28 patients had developed metastases. Fourteen patients
had bone metastases only, 9 visceral metastases only, and 5 a combination of osseous and visceral metastases. Of the 19 women
with skeletal metastases, 17 had preoperative serum BSP values in excess of 24 ng/ml (median BSP values: 48.3 ng/ml for isolated
metastatic bone disease, 30.6 ng/ml for combined metastases), whereas none of the women with visceral metastases only had
elevated serum BSP concentrations (median BSP value: 12.3 ng/ml). The median serum BSP value in the control group (benign
breast disease) was 8.8 ng/ml serum BSP; levels correlated with the size of the primary tumor, but not with any other prognostic
factors. Using a multivariate regression analysis, serum BSP was found to be the most important independent prognostic factor
for the development of skeletal metastasis ( P < 0.001; relative risk, 94); its specificity was 96.7%, and its sensitivity was 89.5%. Our study shows that patients with
preoperatively elevated serum BSP levels are at high risk of subsequent bone metastases in the first years after primary surgery.
The mechanism of BSP in the pathogenesis of skeletal metastases is unclear. Because BSP contains an integrin recognition sequence,
its expression in tumor cells may facilitate their adhesion to the bone surface. However, it is possible that a proportion
of circulation BSP is derived from normal or tumor-induced bone turnover. Breast cancer patients with elevated serum BSP levels
may benefit from osteoprotective adjuvant therapy with bisphosphonates.
: Reperfusion injury is a problem in organ transplantation. Relaxin causes vessel dilation and inhibition of platelet and mast cell activation. The study investigates the protective effect of relaxin ...on liver tissue against cell damage during organ preservation and reperfusion. Liver transplantation was simulated in a model of isolated perfused rat liver. Relaxin was applicated during reperfusion and/or preservation. To quantify cell damage, we examined the perfusate for malonyldialdehyde (MDA) and myeloperoxidase activity (MPO), and liver tissue underwent immunohistochemical study. Relaxin as an additional substance in preserving/reperfusion solution decreases MPO and MDA levels in the perfusate and immunohistochemical study. Relaxin seems to have a protective effect against cell damage in ischemia and reperfusion injury.
Changes in glycosylation are salient features of cancer cells. Here, we report on the diagnostic and therapeutic properties of IDK1, an antibody against tumour associated, hypoglycosylated bone ...sialoprotein (hypo‐BSP). The affinity of the rat monoclonal antibody IDK1 for hypo‐BSP, as determined by microscale thermophoresis, was three orders of magnitude higher than for mature BSP, whereas the mouse monoclonal antibody used had similar affinity for both BSP forms. IDK1 showed no activity against the proliferation or migration of normal or cancer cells growing in vitro. In vivo, however, IDK1 caused dose‐dependent regression of soft tissue and skeletal lesions in nude rats harbouring human MDA‐MB‐231 cells. At optimal dose, 80% of the treated rats showed complete remission of all tumour lesions. Analysis of BSP expression in vitro by fluorescence‐activated cell sorting (FACS) and immunocytochemistry showed basal levels of this protein, which were visible only in a fraction of these cells. Cells of the metastatic cell lines MDA‐MB‐231 and PC‐3 were more often positive for hypo‐BSP. In addition, there was co‐expression of both forms in some cells, but almost no co‐localization; rather, hypo‐BSP was present in the nucleus, and mature BSP was detected extra‐cellularly. Normal osteoblasts and osteoclasts were negative for hypo‐BSP. Breast cancer tissue, however, showed strong expression of mature BSP, which was present intra‐cellularly as well as in vesicles outside cells. Hypo‐BSP was present mainly in lesions from skeletal sites, thus explaining the antineoplastic activity of IDK1, which was high in lesions growing in the vicinity of the skeleton but low in lesions growing subcutaneously. Finally, hypo‐BSP was detected in specimens from breast cancer patients, with a significantly greater intensity in skeletal metastases as compared to the respective primary cancers. In conclusion, IDK‐1 is an antibody with diagnostic and therapeutic applications in skeletal metastases of breast cancer.
The extracellular bone matrix protein bone sialoprotein (BSP) is considered to play an important role in the pathogenesis of lytic skeletal lesions which are associated with severe morbidity in ...breast, prostate or lung cancer patients. In addition to in vitro studies, nude rats were implanted with 10(5) MDA-MB-231 cells transfected with GFP into a small branch of the femoral artery. Osteolytic lesions of the respective hind leg were detected by X-ray and CT analysis as well as by immunohistochemistry. Exposure of MDA-MB-231GFP cells in vitro to an antibody against BSP (0-400 microg/ml) decreased proliferation, colony formation and migration of these cells by up to 95, 83 and 89 T/C%, respectively. In nude rats, pre-incubation of MDA-MB-231GFP cells prior to inoculation (25-100 microg/ml) reduced the mean osteolytic lesion size to 22 T/C% after 90 days of observation (p<0.05). Treatment of overt lytic metastasis with the anti-BSP antibody (10 mg/kg) resulted in a significantly smaller mean lesion size of 57 T/C% at the end of the observation period (p<0.05) as well as in new bone formation. Immunohistochemical analysis revealed the presence of BSP in MDA-MB-231GFP cells and in vessel endothelium cells during processes such as migration and invasion. In conclusion, an anti-BSP antibody decreased proliferation, colony formation and migration of MDA-MB-231GFP cells in vitro and reduced osteolysis besides inducing bone formation in a nude rat model.
PDF
