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An immunochemical and serological study of a patient with rheumatoid arthritis who developed multiple myelorna and was treated with 1-phenylalanine mustard showed a striking difference in the effect of this drug on the rapidly dividing cells, as opposed to the resting plasma cells. The titres of anti-globulin antibodies such as the IgG serum agglutinators and the IgM rheumatoid factors were little altered although the IgG rnyeloma spike has disappeared following therapy. Fractionation of two different serum samples from 1966 and 1970 showed the IgG paraprotein to be serologically inactive for anti-globulin activity. This paraprotein was also characterized by producing only a single IgG precipitin line with horse anti-human whole serum antibody while the normal IgG globulins always showed a double line. [ABSTRACT FROM AUTHOR]

Abstract Background Diminished expression or activity of prostate apoptosis response protein 4 (Par-4) has been demonstrated in a number of cancers, although reports on Par-4 expression during colon cancer progression are lacking. An understanding of the molecular events in conjunction with the genetic networks affected by Par-4 is warranted. Results Colon cancer specimens derived from patients have significantly diminished expression of Par-4 mRNA relative to paired normal colon. Hence, the functional consequences of reintroducing Par-4 into HT29 colon cancer cells were assessed. Overexpression augmented the interaction of Par-4 with NFκB in the cytosol but not nucleus, and facilitated apoptosis in the presence of 5-fluorouracil (5-FU). Analogous findings were obtained when AKT1 pro-survival signaling was inhibited. Transcriptome profiling identified ~700 genes differentially regulated by Par-4 overexpression in HT29 cells. Nearly all Par-4-regulated genes were shown by promoter analysis to contain cis-binding sequences for NFκB, and meta-analysis of patient expression data revealed that one-third of these genes exist as a recurrent co-regulated network in colon cancer specimens. Sets of genes involved in programmed cell death, cell cycle regulation and interestingly the microRNA pathway were found overrepresented in the network. Noteworthy, Par-4 overexpression decreased NFκB occupancy at the promoter of one particular network gene DROSHA, encoding a microRNA processing enzyme. The resulting down-regulation of DROSHA was associated with expression changes in a cohort of microRNAs. Many of these microRNAs are predicted to target mRNAs encoding proteins with apoptosis-related functions. Western and functional analyses were employed to validate several predictions. For instance, miR-34a up-regulation corresponded with a down-regulation of BCL2 protein. Treating Par-4-overexpressing HT29 cells with a miR-34a antagomir functionally reversed both BCL2 down-regulation and apoptosis by 5-FU. Conversely, bypassing Par-4 overexpression by direct knockdown of DROSHA expression in native HT29 cells increased miR-34a expression and 5-FU sensitivity. Conclusion Our findings suggest that the initiation of apoptotic sensitivity in colon cancer cells can be mediated by Par-4 binding to NFκB in the cytoplasm with consequential changes in the expression of microRNA pathway components.

Voltage-gated Na(+) channels (VGSC) have been implicated in the metastatic potential of human breast, prostate, and lung cancer cells. Specifically, the SCN5A gene encoding the VGSC isotype Na(v)1.5 has been defined as a key driver of human cancer cell invasion. In this study, we examined the expression and function of VGSCs in a panel of colon cancer cell lines by electrophysiologic recordings. Na(+) channel activity and invasive potential were inhibited pharmacologically by tetrodotoxin or genetically by small interfering RNAs (siRNA) specifically targeting SCN5A. Clinical relevance was established by immunohistochemistry of patient biopsies, with strong Na(v)1.5 protein staining found in colon cancer specimens but little to no staining in matched-paired normal colon tissues. We explored the mechanism of VGSC-mediated invasive potential on the basis of reported links between VGSC activity and gene expression in excitable cells. Probabilistic modeling of loss-of-function screens and microarray data established an unequivocal role of VGSC SCN5A as a high level regulator of a colon cancer invasion network, involving genes that encompass Wnt signaling, cell migration, ectoderm development, response to biotic stimulus, steroid metabolic process, and cell cycle control. siRNA-mediated knockdown of predicted downstream network components caused a loss of invasive behavior, demonstrating network connectivity and its function in driving colon cancer invasion.

Large granular lymphocyte (LGL) leukemia results from chronic expansion of cytotoxic T cells or natural killer (NK) cells. Apoptotic resistance resulting from constitutive activation of survival signaling pathways is a fundamental pathogenic mechanism. Recent network modeling analyses identified platelet-derived growth factor (PDGF) as a key master switch in controlling these survival pathways in T-cell LGL leukemia. Here we show that an autocrine PDGF regulatory loop mediates survival of leukemic LGLs of both T- and NK-cell origin. We found high levels of circulating PDGF-BB in platelet-poor plasma samples from LGL leukemia patients. Production of PDGF-BB by leukemic LGLs was demonstrated by immunocytochemical staining. Leukemic cells expressed much higher levels of PDGFR-beta transcripts than purified normal CD8(+) T cells or NK cells. We observed that phosphatidylinositol-3-kinase (PI3 kinase), Src family kinase (SFK), and downstream protein kinase B (PKB)/AKT pathways were constitutively activated in both T- and NK-LGL leukemia. Pharmacologic blockade of these pathways led to apoptosis of leukemic LGLs. Neutralizing antibody to PDGF-BB inhibited PKB/AKT phosphorylation induced by LGL leukemia sera. These results suggest that targeting of PDGF-BB, a pivotal regulator for the long-term survival of leukemic LGLs, may be an important therapeutic strategy.

T-cell large granular lymphocyte (LGL) leukemia is characterized by clonal expansion of CD3(+)CD8(+) cells. Leukemic LGLs correspond to terminally differentiated effector-memory cytotoxic T lymphocytes (CTLs) that escape Fas-mediated activation-induced cell death (AICD) in vivo. The gene expression signature of peripheral blood mononuclear cells from 30 LGL leukemia patients showed profound dysregulation of expression of apoptotic genes and suggested uncoupling of activation and apoptotic pathways as a mechanism for failure of AICD in leukemic LGLs. Pathway-based microarray analysis indicated that balance of proapoptotic and antiapoptotic sphingolipid-mediated signaling was deregulated in leukemic LGLs. We further investigated sphingolipid pathways and found that acid ceramidase was constitutively overexpressed in leukemic LGLs and that its inhibition induced apoptosis of leukemic LGLs. We also showed that S1P(5) is the predominant S1P receptor in leukemic LGLs, whereas S1P(1) is down-regulated. FTY720, a functional antagonist of S1P-mediated signaling, induced apoptosis in leukemic LGLs and also sensitized leukemic LGLs to Fas-mediated death. Collectively, these results show a role for sphingolipid-mediated signaling as a mechanism for long-term survival of CTLs. Therapeutic targeting of this pathway, such as use of FTY720, may have efficacy in LGL leukemia.

Loss of p53 function by mutation is common in cancer. However, most natural p53 mutations occur at a late stage in tumor development, and many clinically detectable cancers have reduced p53 expression but no p53 mutations. It remains to be fully determined what mechanisms disable p53 during malignant initiation and in cancers without mutations that directly affect p53. We show here that oncogenic signaling pathways inhibit the p53 gene transcription rate through a mechanism involving Stat3, which binds to the p53 promoter in vitro and in vivo. Site-specific mutation of a Stat3 DNA-binding site in the p53 promoter partially abrogates Stat3-induced inhibition. Stat3 activity also influences p53 response genes and affects UV-induced cell growth arrest in normal cells. Furthermore, blocking Stat3 in cancer cells up-regulates expression of p53, leading to p53-mediated tumor cell apoptosis. As a point of convergence for many oncogenic signaling pathways, Stat3 is constitutively activated at high frequency in a wide diversity of cancers and is a promising molecular target for cancer therapy. Thus, repression of p53 expression by Stat3 is likely to have an important role in development of tumors, and targeting Stat3 represents a novel therapeutic approach for p53 reactivation in many cancers lacking p53 mutations.

Identifying molecular markers for colon cancer is a top priority. Using a pooled sample approach with Affymetrix GeneChip technology, we assayed colon cancers derived from a series of clinical stages to identify molecular markers of potential prognostic value. Of 12000 genes assessed, osteopontin emerged as the leading candidate tumor progression marker. Osteopontin is a secreted glycoprotein known to bind integrins and CD44. Its actual molecular function remains elusive but its increased expression correlates strongly with tumor progression.

The adenomatous polyposis coli (APC) gene, a member of the WNT pathway, has been shown to assign intestinal epithelial cells to a program of proliferation or differentiation through regulation of the beta-catenin/TCF-4 complex. Wild-type APC, in certain cellular contexts, appears to induce differentiation and apoptosis, although mutant forms of APC, known to produce polyps and ultimately cancers, may suppress these events. Here, we show that mutant forms of APC can induce repression of select terminal caspases as a potential means of attenuating responses to apoptotic stimuli. Using gene expression profiling to interrogate the intact intestines of Apc(+/min) mice harboring numerous polyps, we identified a reduction in the mRNA expression of both caspases 3 and 7. We additionally identified a reduction in protein levels of caspase-3, caspase-7, and caspase-9 in human colon cancer specimens known to harbor APC mutations. A reduction in caspase protein levels resulted in resistance to apoptotic-inducing agents and restoration of caspase levels reinstated apoptotic capacities. Consistent with Wnt pathway involvement, dominant negative TCF/LEF induced caspase protein expression. These data provide support for the hypothesis that one of the functions of APC is the regulation of caspase activity and other apoptotic proteins by controlling their expression levels in the cell.

Background: New tumor markers and markers of tumor progression are needed for improved staging and for better assessment of treatment of many cancers. Gene expression profiling techniques offer the opportunity to discover such markers. We investigated the feasibility of sample pooling strategy in combination with a novel analysis algorithm to identify markers., Methods: Total RNA from human colon tumors (n = 60) of multiple stages (adenomas; cancers with modified Astler Collier stages B, C, and D; and liver metastases) were pooled within stages and compared with pooled normal mucosal specimens (n = 10) by using oligonucleotide expression arrays. Genes that showed consistent increases or decreases in their expression through tumor progression were identified. Northern blot analysis was used to validate the findings. All statistical tests were two-sided., Results: More than 300 candidate tumor markers and more than 100 markers of tumor progression were identified. Northern analysis of 11 candidate tumor markers confirmed the gene expression changes. The gene for the secreted integrin-binding protein osteopontin was most consistently differentially expressed in conjunction with tumor progression. Its potential as a progression marker was validated (Spearman's rho = 0.903; P<.001) with northern blot analysis using RNA from an independent set of 10 normal and 43 tumor samples representing all stages. Moreover, a statistically significant correlation between osteopontin protein expression and advancing tumor stage was identified with the use of 303 additional specimens (human cancer = 185, adenomas = 67, and normal mucosal specimens = 51) (Spearman's rho = 0.667; P<.001)., Conclusions: Sample pooling can be a powerful, cost-effective, and rapid means of identifying the most common changes in a gene expression profile. We identified osteopontin as a clinically useful marker of tumor progression by use of gene expression profiling on pooled samples.

Src is an oncoprotein which has been implicated in a number of human malignancies in which it has been shown to be overexpressed and highly activated. The precise mechanism of Src transformation, however, is still poorly understood. We hypothesized that Ras and other farnesylated proteins may mediate Src transformation. To test this hypothesis, v-Src-transfected rat fibroblasts (3Y1) were treated every 72 h with a 15 microM concentration of a farnesyl-transferase inhibitor (FTI). At 2 weeks, a focus formation assay was performed to assess transformation potential. Untreated and FTI-treated v-Src-transfected 3Y1 cells formed a mean of 39 (+/-2.6) and 29.8 (+/-2.9) foci per well, respectively. This 24% decrease was judged to be statistically significant (P = 0.02). Moreover, foci (>90%) in the FTI-treated wells were also consistently smaller than foci in the untreated wells. Western blots with antibody directed toward H-Ras confirmed complete inhibition of Ras farnesylation in the treated cell lines. The specificity of this inhibition was verified by Western blot using antibody specific for Rap1A. The transforming potential of v-Src is inhibited, but not eliminated by FTI treatment. This suggests that v-Src transformation is mediated in part by farnesylated proteins, one of which may be Ras., (Copyright 2001 Academic Press.)

Signal transducer and activator of transcription (STAT) proteins perform key roles in mediating signaling by cytokines and growth factors, including platelet-derived growth factor (PDGF). In addition, Src family kinases activate STAT signaling and are required for PDGF-induced mitogenesis in normal cells. One STAT family member, Stat3, has been shown to have an essential role in cell transformation by the Src oncoprotein. However, the mechanisms by which STAT-signaling pathways contribute to mitogenesis and transformation are not fully defined. We show here that disruption of Stat3 signaling by using dominant-negative Stat3beta protein in NIH 3T3 fibroblasts suppresses c-Myc expression concomitant with inhibition of v-Src-induced transformation. Ectopic expression of c-Myc is able to partially reverse this inhibition, suggesting that c-Myc is a downstream effector of Stat3 signaling in v-Src transformation. Furthermore, c-myc gene knockout fibroblasts are refractory to transformation by v-Src, consistent with a requirement for c-Myc protein in v-Src transformation. In normal NIH 3T3 cells, disruption of Stat3 signaling with dominant-negative Stat3beta protein inhibits PDGF-induced mitogenesis in a manner that is reversed by ectopic c-Myc expression. Moreover, inhibition of Src family kinases with the pharmacologic agent, SU6656, blocks Stat3 activation by PDGF. These findings, combined together, delineate the signaling pathway, PDGF --> Src --> Stat3 --> Myc, that is important in normal PDGF-induced mitogenesis and subverted in Src transformation.

Since the original identification of a transmissible agent responsible for the development of tumors in chickens, now known to be a retrovirus encoding the v-src gene, significant progress has been made in defining the potential functions of its human homolog, SRC. The product of the human SRC gene, c-Src, is found to be over-expressed and highly activated in a wide variety of human cancers. The relationship between Src activation and cancer progression appears to be significant. Moreover, Src may have an influence on the development of the metastatic phenotype. This review discusses the data supporting a role for c-Src as a critical component of the signal transduction pathways that control cancer cell development and growth, and provides the rationale for targeting Src in drug discovery efforts.

The discovery of Rous sarcoma virus (RSV) led to the identification of cellular Src (c-Src), a non-receptor tyrosine kinase, which has since been implicated in the development of numerous human cancers. c-Src has been found to be highly activated in colon cancers, particularly in those metastatic to the liver. Studies of the mechanism of c-Src regulation have suggested that c-Src kinase activity is downregulated by phosphorylation of a critical carboxy-terminal tyrosine (Tyr 530 in human c-Src, equivalent to Tyr 527 in chicken Src) and have implied the existence of activating mutations in this C-terminal regulatory region. We report here the identification of a truncating mutation in SRC at codon 531 in 12% of cases of advanced human colon cancer tested and demonstrate that the mutation is activating, transforming, tumorigenic and promotes metastasis. These results provide, for the first time, genetic evidence that activating SRC mutations may have a role in the malignant progression of human colon cancer.

Current models suggest that colon cancer initiation and progression are secondary to both the activation of oncogenes and the deletion of tumor suppressor genes. The role of each, however, is still poorly understood, particularly with regard to the induction of metastasis. We hypothesized that genetic differences exist between tumors that metastasize distantly and those that do not, and that oncogenes and tumor suppressor genes participate equally in this process. To address this hypothesis, human tumor specimens from localized [tumor-node-metastasis (TNM) stage I-III] and primary colon cancers (n = 10) were directly compared with metastatic (TNM stage IV) lesions (n = 10) using comparative genomic hybridization analysis. Although several alterations were shared equally between primary tumors and metastases (+7q, +19q, and +20q), two patterns of distinguishing alterations were observed: (a) alterations that were more extensive in liver metastases than in primary tumors (+8q, +13q, -4p, -8p, -15q, -17p, -18q, -21q, and -22q); and (b) alterations that were unique to metastatic lesions (-9q, -11q, and -17q). Overall, genetic losses were more common than gains, and, more importantly, the number of losses/tumor was significantly higher for metastases than for primary tumors (9.3 + 1.3 versus 4.1 + 0.7; P = 0.00062, Wilcoxon's rank-sum test). The distinct predominance of genetic losses in the metastatic lesions when compared with the primary localized tumors provides evidence that the metastatic phenotype is induced by the deletion of tumor suppressor genes and permits the construction of physical maps targeting regions where novel tumor suppressor genes are likely to exist.

Recent data suggest that signal transduction may have a critical role in the development and regulation of the metastatic phenotype. Here, we investigated the role of c-Src activation in the process of human colon cancer metastasis to the liver. Our data, derived from two different sets of human colon cancer cell line metastatic variants, suggest that not only do highly-metastatic cells display constitutively elevated c-Src protein kinase activity when compared to poorly metastatic cells, but also that receptor tyrosine kinases participate in the ligand-activation of c-Src above basal levels. Specifically, the epidermal growth factor receptor (EGFR), p185HER2/Neu and the hepatocyte growth factor receptor (c-Met) appear to be linked to the process because they preferentially activate c-Src in highly-metastatic cells. EGFR was found to associate with c-Src in colon cancer cells and specific inhibitors of the EGFR resulted in a reduction of c-Src activity to basal levels. In addition, c-Src transfectants displayed partially-activated EGFRs, suggesting a feedback role for c-Src in the regulation of the EGFR. p185HER2/Neu was also identified in immunocomplexes of c-Src following ligand activation of the EGFR, but only in highly-metastatic cells. Collectively, these observations suggest a paradigm whereby c-Src interacts with multiple cell-surface growth factors in a catalytic fashion for the development of tumor cells with metastatic potential.

Whereas genetic paradigms are now defined for the development of human colon cancer, little is known regarding the mechanisms that regulate development of the metastatic phenotype. Recent reports have indirectly linked the expression and activation of c-Src to the process of human colon cancer metastasis. Whereas v-Src, a highly activated mutational derivative of c-Src, has been shown to induce metastasis, normal c-Src has not been tested for this property. We hypothesized that c-Src overexpression in the milieu of a poorly metastatic cancer cell might permit the development of a highly metastatic cell. Two poorly metastatic human colon cancer cell lines were stably transfected with expression vectors encoding normal human c-Src. Clones producing 4-10-fold more c-Src than controls were injected s.c. and intrasplenically into the nude mouse to assess primary tumor growth and liver metastatic potential. Whereas metastatic potential was unaffected, primary tumor growth in vivo was significantly enhanced by c-Src overexpression. No effects on rates of tumor cell proliferation were seen in vitro. Our findings suggest that normal c-Src may be necessary but is insufficient for the induction of the metastatic phenotype.

Reproductive dysfunction in the diabetic female rat is associated with impaired folliculogenesis, reduced corpus luteum progesterone output, and spontaneous abortion. The underlying mechanism for reduced steroid production remains unresolved. In this study we examined whether or not diabetes alters levels of P450 side-chain cleavage enzyme (P450scc), 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), or the cholesterol transport proteins, steroidogenic acute regulatory (StAR) protein and sterol carrier protein-2 (SCP2), leading to lower progesterone levels and pregnancy loss. Rats (Day 3 pregnant) received an injection of streptozotocin (STZ, 60 mg/kg; i.v.) to induce a diabetic state; P450scc, 3 beta-HSD, and SCP2 were examined by Western and Northern blot analysis in ovarian tissue 12 days after injection of STZ (diabetic rats, n = 12) or vehicle (nondiabetic rats, n = 12). Serum progesterone, triglyceride, and beta-hydroxybutyrate (beta-HBA) levels were also examined. Results indicate that diabetic rats that aborted (diabetic-fetus [Ft], n = 6) had significantly lower progesterone levels (7.04 +/- 2.6 ng/ml; p < 0.004) than nondiabetic animals (108.6 +/- 5.15 ng/ml) and diabetic +Ft animals (74.3 +/- 8.9 ng/ml, n = 6). Western blot analysis of ovarian P450scc and 3 beta-HSD in the nondiabetic rats and the diabetic rats with fetuses indicated no significant difference. In contrast, ovaries from diabetic animals without fetuses had significantly lower SCP2 levels (p < 0.017) compared to controls. Concomitant with the reduction in SCP2, a 58-kDa SCP2-immunoreactive protein, referred to as sterol carrier protein-X (SCPx), increased significantly (p < 0.001). The C-terminal sequence of SCPx is identical to SCP2, while its N-terminal region is homologous with 3-oxoacyl coenzyme A thiolase, an enzyme involved in fatty acid metabolism. Increased SCPx expression coincided with increased serum triglyceride and beta-HBA levels, suggesting that the enhanced SCPx level may coincide with an ovarian shift to fatty acid metabolism. When SCPx steady-state mRNA levels were measured using an SCPx-specific riboprobe (280-bp protected fragment) in a ribonuclease protection assay, ovarian SCPx mRNA levels in the diabetic animals were increased 4.2-fold compared to control SCPx mRNA levels. Ovarian StAR mRNA levels were increased slightly in the diabetic animals, and ovarian P450scc and 3 beta-HSD mRNA levels were increased 3-fold in the diabetic animals that aborted relative to the nondiabetic animals and the +Ft diabetic animals. Results of this study confirm that SCPx mRNA levels are elevated following diabetes onset and that StAR, P450scc, and 3 beta-HSD mRNA levels do not correspond with the reduced steroid hormone profile associated with diabetes. These results are concordant with the possibility that reduced steroid levels in the diabetic animals reflect a loss of SCP2-mediated cholesterol transport capacity as SCPx/3-oxoacyl coenzyme A thiolase expression is enhanced.

Biosynthesis of molybdopterin was followed in the yeast, Pichia canadensis, using labeled precursors. High performance liquid chromatography analysis of extracts from cells labeled with [U-14C]guanosine showed that the label was incorporated into the molybdopterin oxidation product, dephospho Form A. Dephospho Form A isolated from cells labeled with [U-14C,5'-3H]guanosine was devoid of tritium, indicating partial loss of the ribose moiety of guanosine during the synthesis of molybdopterin. In vivo labeling of P. canadensis using [7-14C]neopterin and [6,7,1-14C]hydroxymethylpterin led to label from both compounds appearing in dephospho Form A as well as in folic acid in wild type cells. When these labeled precursors were incubated with P. canadensis mutants blocked in molybdopterin synthesis, only folic acid was labeled. These results suggest a shared pathway in the biosyntheses of molybdopterin and folic acid. [6-14C]Glucose labeling experiments led to exclusive incorporation into the 4'-position of dephospho Form A but not in folic acid. It is proposed that molybdopterin synthesis branches from the folic acid biosynthetic pathway at dihydrohydroxymethylpterin and that a 3-carbon phosphorylated compound such as glyceraldehyde 3-phosphate may condense with dihydrohydroxymethylpterin to form the 4-carbon side chain precursor to molybdopterin.

1. Exposure of the rotifer Brachionus plicatilis to elevated temperature resulted in the synthesis of a number of proteins, including a prominent one of 58,000 Da (SP58). 2. This protein is immunologically crossreactive with the 65,000 Da heat shock protein of the moth Heliothis virescens, which is a member of a highly conserved family of mitochondrial proteins. 3. Exposure of rotifers to sublethal doses of CuSO4 leads to a 4-5-fold increase in abundance of SP58, with maximum increase occurring at a dose that is approximately 5% of the LC50 for that compound. 4. A similar response was seen with tributyl tin (TBT). Kinetics of induction were sigmoidal, with induction occurring in the range of 20-30 micrograms/l. 5. No response was observed when rotifers were exposed to aluminum chloride, mercury chloride, pentachlorophenol, sodium arsenite, sodium azide, sodium dodecyl sulfate, or zinc chloride. 6. These results indicate that changes in stress protein abundance may prove useful as a biomarker of exposure to particular toxicants.

Weekly treatment with low-dose oral methotrexate (MTX) was compared with daily auranofin (AUR) treatment in a 36-week double-blind, randomized, multicenter study of 281 patients with active, adult-onset rheumatoid arthritis. Both treatment groups showed significant improvement by the usual measures of clinical efficacy. The response with MTX occurred earlier and was consistently greater than that with AUR. An intent-to-treat analysis showed significantly greater improvement (P less than 0.01) with MTX for painful and swollen joint counts and physician and patient global assessments of disease activity. Adverse reactions were reported more frequently in the AUR group, and more AUR-treated patients were withdrawn from the study because of toxicity. MTX was thus more effective and better tolerated than AUR in this study.

Renal homotransplantaion and chronic hemodialysis are accepted methods of treating end-stage kidney disease. However, these procedures are fraught with complications involving bones, joints, and soft tissues. Transplantation and immunosuppressive therapy problems include "connective tissue-like" reactions, infections in joints and avascular necrosis of bone. Long term hemodialysis may accentuate secondary hyperparathyroidism, renal osteodystrophy, and metastatic calcification, which can be minimized by phosphorous control or calcium loading in the dialysate. In the presence of osteomalacia, vitamin D may be helpful and parathyroidectomy is indicated if autonomy is present. In one patient undergoing long term hemodialysis, a chalky material was aspirated from the olecranon bursa. Two inorganic solid phases were identified as being present - a major phase, octacalcium phosphate (ocp) and a minor phase, calcite (CaCO3). Because of its elusive properties, the role of OCP in biological systems is poorly known and can easily escape detection. Methods of identification of OCP and its potential role in crystal deposition syndromes are discussed.