Urinary Prothrombin Fragment Research Articles

Role of Noninvasive Urinary Prothrombin Fragment 1 + 2 to Measure Blood Coagulation Indices and Dose of Acenocoumarol.

PF1 + 2 plasma levels are a crucial indicator for assessing anticoagulant action in individuals receiving anticoagulant treatment. Urine also has PF1 + 2 levels due to its molecular size. Hence, the present study aims to measure urinary prothrombin fragment 1 + 2 (uPF1 + 2) in patients taking anticoagulants in order to divulge a noninvasive surrogate marker of PT-INR of blood coagulopathy. A total of 205 people participated in the study: 104 patients on acenocoumarol (AC) and 101 healthy controls (HC). Clinical parameters, including PT-INR, urinary creatinine, etc., were measured in all subjects. To evaluate uPF1 + 2 in samples, MALDI-TOF-MS, Western blot analysis, and ELISA tests were used. The MALDI-TOF-MS results showed the presence of uPF1 + 2 in both AC and HC urine samples. The Western blot, ELISA experiment, and unpaired t test results displayed that the patients with AC had significantly increased levels of uPF1 + 2 compared to HC. A regression study showed a strong positive relation between blood-based PT-INR and uPF1 + 2. ROC validation also revealed the clinical efficacy of uPF1 + 2. For the goal to monitor anticoagulant medication, the present study highlights PF1 + 2, which describes the overall hemostatic capacity and might be utilized in addition to or instead of PT-INR.

Renal caliculi: Types, mechanism, therapeutic approaches encompassing role of GAGS, MGP, Hormones, UPTF1, CAI, Osteopontin

Kidney stones are deposits in the renal pelvis, calyces, and ureters and reside in urine. Kidney stones undergo biomineralization pathogenesis via nucleation, aggregation, and growth of caliculi. The greater prevalence of kidney stones in men than in women may be due to the link between sex hormones. Kidney equilibrium is maintained with glycosaminoglycans inhibiting growth and aggregation. Sialylated glycoforms of urinary prothrombin fragment 1 prevent calcium stone development. Crystal adherence to tubules is inhibited by CAI, and osteopontin inhibits calculi formation. Medical treatments involve the use of alpha blocker, potassium citrate, thiazide, NSAIDS, opioids, antiemetics and other drugs used in treatment of kidney stone, Alpha adrenoceptor blockers, calcium channel blockers and corticosteroids help to expel renal stones, chemolytic treatment and it could be necessary to remove stones surgically if they are affecting kidney function with the use of techniques. Use of catheter, ultrasound, using a flexible scope equipped with a laser, HDAC inhibitors and many are recent advances in treatment lithiasis.

Urinary Prothrombin Fragment 1 + 2 as an Endogenous Marker of Venous Thromboembolism

Urinary Prothrombin Fragment 1 + 2 as an Endogenous Marker of Venous Thromboembolism

Prevalence, pathophysiological mechanisms and factors affecting urolithiasis.

The formation of urinary stone, urolithiasis, is one the oldest known disease affecting human throughout different civilizations and times. The exact pathophysiological mechanism of urolithiasis is not yet clear, as these calculi are of various types and too complex for simple understanding. A single theory cannot explain its formation; therefore, different theories are presented in various times for its explanation like free particle, fixed particle, Randall's plaque theory. In addition, various factors and components are identified that play an important role in the formation of these urinary calculi. In this review, composition of kidney stones, its prevalence/incidence, explanation of pathophysiological mechanisms and role of various factors; urinary pH, uric acid, parathyroid hormone, citrate, oxalate, calcium and macromolecules; osteopontin, matrix Gla protein, kidney injury molecules, urinary prothrombin fragment-1, Tamm-Horsfall protein, inter-α-inhibitors, have been discussed in detail.

Nephrolithiasis: molecular mechanism of renal stone formation and the critical role played by modulators.

Urinary stone disease is an ailment that has afflicted human kind for many centuries. Nephrolithiasis is a significant clinical problem in everyday practice with a subsequent burden for the health system. Nephrolithiasis remains a chronic disease and our fundamental understanding of the pathogenesis of stones as well as their prevention and cure still remains rudimentary. Regardless of the fact that supersaturation of stone-forming salts in urine is essential, abundance of these salts by itself will not always result in stone formation. The pathogenesis of calcium oxalate stone formation is a multistep process and essentially includes nucleation, crystal growth, crystal aggregation, and crystal retention. Various substances in the body have an effect on one or more of the above stone-forming processes, thereby influencing a person's ability to promote or prevent stone formation. Promoters facilitate the stone formation while inhibitors prevent it. Besides low urine volume and low urine pH, high calcium, sodium, oxalate and urate are also known to promote calcium oxalate stone formation. Many inorganic (citrate, magnesium) and organic substances (nephrocalcin, urinary prothrombin fragment-1, osteopontin) are known to inhibit stone formation. This review presents a comprehensive account of the mechanism of renal stone formation and the role of inhibitors/promoters in calcium oxalate crystallisation.

Urinary prothrombin fragment 1+2 in patients with venous thrombosis and myocardial infarction

Patients with venous-thromboembolism (VTE) and myocardial infarction (MI) have elevated prothrombin fragment 1+2 (F1+2) levels. In patients with postoperative VTE, urinary F1+2 (uF1+2) was higher than in individuals without VTE. To explore the relationship between plasma and uF1+2 we performed a pilot study in patients with thrombotic events and healthy controls. In 40 patients with VTE or MI, and 25 age- and sex-matched healthy controls, F1+2 and D-dimer levels were measured in urine and plasma within 48h after diagnosis. In addition, in all subjects renal function was assessed. Plasma and uF1+2 levels were positively correlated. Compared to controls, patients with VTE had higher levels of both plasma F1+2 (271 vs 160pmolL(-1), p<0.05) and uF1+2 levels (38 vs 28pmolL(-1)), the latter, however, was not statistically significant. Patients with acute MI had similar F1+2 levels as controls in both plasma and urine. Differences in urinary F1+2 levels could not be attributed to differences in concentrations of creatinine or albumin in spot urine samples. Overall, D-dimer and F1+2 levels in urine were extremely low in all groups.

Association between Human Prothrombin Variant (T165M) and Kidney Stone Disease

We previously reported the association between prothrombin (F2), encoding a stone inhibitor protein - urinary prothrombin fragment 1 (UPTF1), and the risk of kidney stone disease in Northeastern Thai patients. To identify specific F2 variation responsible for the kidney stone risk, we conducted sequencing analysis of this gene in a group of the patients with kidney stone disease. Five intronic SNPs (rs2070850, rs2070852, rs1799867, rs2282687, and rs3136516) and one exonic non-synonymous single nucleotide polymorphism (nsSNP; rs5896) were found. The five intronic SNPs have no functional change as predicted by computer programs while the nsSNP rs5896 (c.494 C>T) located in exon 6 results in a substitution of threonine (T) by methionine (M) at the position 165 (T165M). The nsSNP rs5896 was subsequently genotyped in 209 patients and 216 control subjects. Genotypic and allelic frequencies of this nsSNP were analyzed for their association with kidney stone disease. The frequency of CC genotype of rs5896 was significantly lower in the patient group (13.4%) than that in the control group (22.2%) (P = 0.017, OR 0.54, 95% CI 0.32–0.90), and the frequency of C allele was significantly lower in the patient group (36.1%) than that in the control group (45.6%) (P = 0.005, OR 0.68, 95% CI 0.51–0.89). The significant differences of genotype and allele frequencies were maintained only in the female group (P = 0.033 and 0.003, respectively). The effect of amino-acid change on UPTF1 structure was also examined by homologous modeling and in silico mutagenesis. T165 is conserved and T165M substitution will affect hydrogen bond formation with E180. In conclusion, our results indicate that prothrombin variant (T165M) is associated with kidney stone risk in the Northeastern Thai female patients.

Decreased expression of vitamin K epoxide reductase complex subunit 1 in kidney of patients with calcium oxalate urolithiasis

Urinary prothrombin fragment 1 (UPTF1) is a potent inhibitor of urinary stone formation. UPTF1 exerts such inhibitory effect by effective γ-carboxylation in which vitamin K epoxide reductase complex subunit 1 (VKORC1), the rate-limiting enzyme, is involved. This study examined the correlation between VKORC1 expression and calcium oxalate urolithiasis. The renal cortex samples were obtained from patients undergoing nephrectomy and then divided into 3 groups: urolithiasis group, control group A [hydronephrosis-without-stone (HWS) group], control group B (normal control group). The localization and expression of VKORC1 in renal tissues were determined by using immunohistochemistry, immunofluorescence microscopy, Western blotting and SYBR Green I real-time reverse-transcription PCR. The rapid amplification of cDNA ends (RACE) were conducted to obtain the 3'- and 5'-untranslated region (UTR) of VKORC1. The results showed that VKORC1 was located in the cytoplasm of renal tubular epithelial cells. The expression of VKORC1 in the urolithiasis group was significantly lower than that in the other two control groups (P<0.05). Moreover, the 3'- and 5'-UTR sequence of the VKORC1 gene was successfully cloned. No insertion or deletion was found in the 3'- and 5'-UTR. However, a 171-bp new base sequence was discovered in the upstream of 5'-UTR end in the urolithiasis group. It was concluded that the decreased expression of VKORC1 may contribute to the development of calcium oxalate urolithiasis in the kidney.

Urinary Prothrombin Fragment 1+2 in relation to Development of Non-Symptomatic and Symptomatic Venous Thromboembolic Events following Total Knee Replacement.

Prothrombin fragment 1+2 is excreted in urine (uF1+2) as a result of in vivo thrombin generation and can be a marker of coagulation status after an operative procedure. This study compared uF1+2 levels in patients with symptomatic and non-symptomatic venous thromboembolism (VTE) after total knee replacement (TKR) and in event-free sex- and age-matched controls. Significantly higher median uF1+2 levels were seen in the VTE patients on days 1, 3, and the day of venography (mostly day 7) after TKR compared with controls. The uF1+2 levels tended to be high in some patients with symptomatic VTE; however, the discriminatory efficacy of the test could not be evaluated. In conclusion, this study showed that patients with VTE tend to have significantly higher uF1+2 levels compared with patients without events between days 1 and 7 after TKR surgery. Measurement of uF1+2 could provide a simple, non-invasive clinical test to identify patients at risk of VTE.

Face‐specific binding of prothrombin fragment 1 and human serum albumin to inorganic and urinary calcium oxalate monohydrate crystals

To compare the intracrystalline distributions of prothrombin fragment 1 (PTF1) and human serum albumin (HSA) within inorganic and urinary calcium oxalate (CaOx) monohydrate (COM) crystals and to determine whether binding of PTF1 can be explained by interactions between particular gamma-carboxyglutamic (Gla) residues and atomic arrays on individual faces of the COM crystal. MATERIALS AND METHODS COM: crystals were precipitated from inorganic solutions and ultrafiltered urine containing fluorescent HSA or PTF1 at different relative concentrations and examined by fluorescence microscopy. Accelrys Materials Studio and Discovery Studio were used to model the binding of PTF1 to the top, side and apical faces of the COM crystal. PTF1 alone always adsorbed predominantly to the COM apical surfaces, while HSA bound principally to the side faces under inorganic conditions, but to the apical faces in urine. In the presence of each other, both proteins competed for adsorption to the apical faces, with attachment of PTF1 dominating over that of HSA. Modelling showed that urinary PTF1 had equal theoretical bonding potential for all three COM surfaces. (i) Anisotropic inclusion of HSA and PTF1 into urinary and inorganic COM crystals results from their preferential binding to specific COM faces; (ii) the binding preference of HSA differs under inorganic and urinary conditions; (iii) preferential binding of PTF1 to the apical faces of COM is more complex than can be explained by interactions between Gla groups and surface atomic arrays; (iv) future studies of interactions between urinary proteins and stone mineral crystal surfaces should be performed in urine.

Differences in urinary prothrombin fragment 1 + 2 levels after total hip replacement in relation to venous thromboembolism and bleeding events.

Prothrombin fragment 1 + 2 is excreted in urine (uF1 + 2) as a result of thrombin generation and, therefore, may be a useful marker of coagulation status. To assess uF1 + 2 levels after total hip replacement (THR) in patients with venous thromboembolism (VTE) and bleeding events. This study was conducted in parallel with a prospective, dose-finding study evaluating the efficacy and safety of different doses of rivaroxaban (Xarelto, Bayer HealthCare AG, Wuppertal, Germany) for thromboprophylaxis, relative to enoxaparin. Deep vein thrombosis was diagnosed by mandatory venography performed 5-9 days after THR, or earlier if symptomatic. Symptomatic pulmonary embolism was diagnosed by objective testing. Bleeding complications were registered and stratified into major bleeding, clinically relevant, non-major bleeding, and minor bleeding, using predefined criteria. Eighty-four patients had a VTE and 57 patients had a bleeding event (n = 722). Significantly higher median uF1 + 2 levels were observed in the VTE group on day 3 after THR (P = 0.03), compared with control. Median uF1 + 2 levels were lower in the bleeding group on day 3 after THR (P = 0.005) and on the day of venography (P = 0.36), compared with control. Comparisons between the VTE and bleeding groups showed significantly lower median uF1 + 2 levels in the bleeding group on day 3 after THR and on the day of venography (P < 0.0001 and P = 0.006, respectively). Measurement of uF1 + 2 could provide a simple clinical test to evaluate non-invasively the intensity of coagulation activation after THR. However, further studies are required to confirm these encouraging preliminary results.

Glycosylation of prothrombin fragment 1 governs calcium oxalate crystal nucleation and aggregation, but not crystal growth

Urinary glycoproteins play an important role in the modulation of calcium oxalate crystallisation. In several cases, this has been attributed to glycosylation of the proteins as evidenced by urinary prothrombin fragment 1 where there is a correlation between sialylation and calcium oxalate kidney stone disease. In the present study, plasma-derived prothrombin fragment 1 (PTF1) was enzymatically modified in order to generate its asialo and aglyco forms. The parent glycoprotein and its two glycoforms were used in calcium oxalate crystallisation studies to assess the role of the carbohydrate moeity in PTF1's potent inhibitory activity. The glycans inhibited crystal aggregation and promoted crystal nucleation, but had no effect on crystal growth. The terminal sialic acid residues had a small effect on inhibition of crystal aggregation whereas they contributed significantly to promotion of nucleation. These results indicate that glycosylation of PTF1 governs calcium oxalate crystal nucleation and aggregation but it does not affect the protein's role in inhibiting crystal growth. Since promotion of nucleation and inhibition of aggregation are both regarded as protective mechanisms against calcium oxalate urinary stone formation, the kringle domain on which the glycans are located is implicated in PTF1's inhibitory activity. It is speculated that modifications in the glycosylation of urinary PTF1 in stone-formers may regulate its capacity to protect against calcium urolithiasis.

Effect of urine fractionation on attachment of calcium oxalate crystals to renal epithelial cells: implications for studying renal calculogenesis

Our aim was to determine whether fractionation of human urine affects the attachment of calcium oxalate monohydrate (COM) crystals to renal cells. Urine collected from six healthy subjects was fractionated into sieved (S), centrifuged (C), centrifuged and filtered (CF), or ultrafiltered (UF). Attachment of [(14)C]COM crystals to Madin-Darby canine kidney (MDCK) cells was studied after precoating the crystals or the cells with the urine fractions and by using the same fractions as the binding medium. Protein content of the fractions and precoated crystals was analyzed with SDS-PAGE and Western blotting. All urine fractions inhibited crystal attachment. When fractions from the six urine samples were used to precoat the cells, the median inhibitions of crystal adhesion ( approximately 40%) were not significantly different. Median inhibition after preincubation of crystals was the same for the S, C, and CF fractions ( approximately 40%) but significantly greater than for the UF fraction ( approximately 28%). When fractions were used as the binding medium, median inhibitions decreased from 64% in the S fraction to 47 (C), 42 (CF), and to 29% (UF). SDS-PAGE analysis showed that centrifugation and filtration reduced the amount of Tamm-Horsfall glycoprotein (THG), which was confirmed by Western blotting. Human serum albumin, urinary prothrombin fragment 1, and osteopontin, but not THG, were present in demineralized extracts of the precoated crystals. Fractionation of human urine affects the attachment of COM crystals to MDCK cells. Hence future studies investigating regulation of crystal-cell interactions should be carried out in untreated urine as the binding medium.

Renal prothrombin mRNA is significantly decreased in a hyperoxaluric rat model of nephrolithiasis

Although urinary prothrombin fragment 1 (UPTF1) possesses several hallmarks expected of a regulatory protein in urolithiasis, its precise role remains unknown. To determine the relationship between renal prothrombin (PT), the parent molecule of UPTF1, and lithogenesis, this study quantified and compared levels of renal PT mRNA in healthy rats (n = 10) and rats rendered lithogenic (n = 10) by ingestion of 0.75% ethylene glycol for 8 weeks. Studies included morphological and histological examination of the kidneys with scanning electron microscopy of the urinary filtrates of control and experimental animals. Haematuria and calcium oxalate (CaOx) crystals occurred in the urine of all experimental rats, but not in those of controls. Histological examination showed birefringent nephroliths and associated damage in kidneys of lithogenic rats, which were not seen in the control group. The amounts of total RNA extracted from both groups of rats were similar, but the median ratio of PT to beta-actin transcript of 11.14 x 10(-4) (10.65 x 10(-4) +/- 2.24 x 10(-4)) in the control rats was significantly (p < or = 0.001) reduced to 6.47 x 10(-4) (6.57 x 10(-4) +/- 2.72 x 10(-4)) in the lithogenic group. These results demonstrate that renal PT mRNA is reduced by approximately 42% in lithogenic rats and confirm the existence of a direct association between renal PT synthesis and calculogenesis. Attempts to compare renal PT and urinary levels of PTF1 were unsuccessful because of interference from hepatic PT circulating in the blood, haematuria, and the presence of urinary CaOx crystals. This is the first report of a significant reduction in the renal expression of a urinary protein well documented to inhibit CaOx crystal growth and aggregation in undiluted human urine in vitro.

Protein regulation of intrarenal crystallization

In this review we discuss the key role renal proteins appear to play during initiation and growth of renal stones. Specific macromolecules have been identified in urine that can regulate crystal nucleation, growth, aggregation, and adhesion to renal cells. Many are incorporated into the matrix of crystals while they grow, including urinary prothrombin fragment 1, thereby increasing crystal susceptibility to degradation by cellular proteases. None of these macromolecular inhibitors appears to be quantitatively decreased in the urine of stone formers, although functional deficiencies thought due to abnormal glycosylation have been implicated, especially in the case of Tamm Horsfall protein. Increasing information is available on the nature and expression of crystal binding molecules on the renal cell surface, and they appear to be maximally expressed in response to stressful stimuli. Studies that employ atomic force microscopy and knockout mice are now being used to further clarify macromolecule-crystal interactions. The exact series of events that transform supersaturation to crystal formation and renal stones are poorly defined. Multiple anchored and soluble renal proteins potentially modulate or even regulate these events. A combination of proteomics and molecular biology seems likely to unravel these critical mediators in the coming years.

Sialylation of urinary prothrombin fragment 1 is implicated as a contributory factor in the risk of calcium oxalate kidney stone formation

Urinary glycoproteins are important inhibitors of calcium oxalate crystallization and adhesion of crystals to renal cells, both of which are key mechanisms in kidney stone formation. This has been attributed to glycosylation of the proteins. In South Africa, the black population rarely form stones (incidence < 1%) compared with the white population (incidence 12-15%). A previous study involving urinary prothrombin fragment 1 from both populations demonstrated superior inhibitory activity associated with the protein from the black group. In the present study, we compared N-linked and O-linked oligosaccharides released from urinary prothrombin fragment 1 isolated from the urine of healthy and stone-forming subjects in both populations to elucidate the relationship between glycosylation and calcium oxalate stone pathogenesis. The O-glycans of both control groups and the N-glycans of the black control samples were significantly more sialylated than those of the white stone-formers. This demonstrates a possible association between low-percentage sialylation and kidney stone disease and provides a potential diagnostic method for a predisposition to kidney stones that could lead to the implementation of a preventative regimen. These results indicate that sialylated glycoforms of urinary prothrombin fragment 1 afford protection against calcium oxalate stone formation, possibly by coating the surface of calcium oxalate crystals. This provides a rationale for the established roles of urinary prothrombin fragment 1, namely reducing the potential for crystal aggregation and inhibiting crystal-cell adhesion by masking the interaction of the calcium ions on the crystal surface with the renal cell surface along the nephron.

Urinary macromolecular inhibition of crystal adhesion to renal epithelial cells is impaired in male stone formers

Retention of microcrystals that form in tubular fluid could be a critical event in kidney stone formation. This study was performed to determine if urinary macromolecules from stone-forming (SF) individuals have reduced ability to inhibit crystal adhesion to renal cells. A first morning whole urine (WU) sample was obtained from 24 SF subjects (17 males and 7 females) and 24 age-, race-, and sex-matched controls (C). An aliquot of urine was centrifuged and an ultrafiltrate (UF) free of macromolecules >10 kD and 10x concentrate (U(conc)) were prepared. Supplementing UF with increasing amounts of U(conc) to return the macromolecule concentration to 0.25x, 0.5x, or 1x of baseline progressively decreased crystal binding to cells. This effect was blunted in the male SF group compared to controls (P < 0.05, SF vs. C, for UF plus 0.25x macromolecules). No difference was apparent in the female groups. In order to identify responsible macromolecule(s), calcium oxalate monohydrate (COM) crystals were coated with U(conc) and adherent proteins then released and probed by Western blot. Coated COM crystals from male controls contained 3.5-fold more Tamm-Horsfall protein (THP) than SF subjects (P < 0.01). COM crystal coating with other proteins did not consistently differ between the groups. COM crystal coating by urinary prothrombin fragment 1 (UPTF1, P < 0.05) and crystal adhesion inhibitor (CAI) (P= 0.09) correlated with decreased crystal binding to cells, whereas coating with osteopontin (OPN) correlated with increased adhesion tendency (P < 0.05). Urinary macromolecules >10 kD coat COM crystals and block their adhesion to renal cells. This capacity appears to be blunted in male but not female SF individuals. Multiple urinary proteins may play a role in renal cell-urinary crystal interactions, and THP appears to be one of the more important ones.

Proteolysis and partial dissolution of calcium oxalate: a comparative, morphological study of urinary crystals from black and white subjects

Crystal adherence to the renal epithelium is widely regarded as a probable mechanism of stone formation. Intracrystalline proteins may provide access to the core of urinary crystals and thereby facilitate the dismantling of these crystals after their attachment to and phagocytosis by renal epithelial cells. The present study investigated the role of proteolysis and limited dissolution of urinary calcium oxalate (CaOx) crystals in South Africa's white and black populations with a view to understanding the remarkably low stone incidence in the black population compared with the whites. CaOx crystals were precipitated from filtered urine or ultrafiltered urine dosed with an intracrystalline protein, urinary prothrombin fragment 1 (UPTF1), isolated from white and black subjects. The crystals were fractured and subjected to proteolysis and/or limited dissolution before examination using field emission scanning electron microscopy (FESEM). FESEM data showed that CaOx crystals from white and black subjects were eroded by treatment with proteases. Cathepsin D caused the most significant crystal erosion, and more noticeable degradation of CaOx monohydrate (COM) crystals compared to CaOx dihydrate (COD). Limited dissolution studies showed the unique ultrastructures and fragmentation processes of COM and COD crystals. COM crystals appeared to be more susceptible to degradation and dissolution than CODs. Since COMs are predominant in blacks, compared with COD crystals from whites, it is speculated that the lower stone rate amongst South African blacks might be attributed partly to their more efficient destruction of retained COM crystals.

EFFECTS OF URINARY PROTHROMBIN FRAGMENT 1 IN THE FORMATION OF CALCIUM OXALATE CALCULUS

We investigated the effects of urinary prothrombin fragment 1 in the formation of calcium oxalate urolithiasis. Fresh urine and renal parenchyma from patients with calcium oxalate calculus and normal controls were collected. Urinary prothrombin fragment 1 was isolated and purified from urine. It was identified by sodium dodecyl sulfide-polyacrylamide gel electrophoresis and analysis of its first 13 N-amino acids. The inhibitory activity of urinary prothrombin fragment 1 on calcium oxalate crystal growth was tested by the seeded crystallization technique. Meanwhile, the gamma-carboxyglutamic acid composition of urinary prothrombin fragment 1 was analyzed by a previously described method and genetic mutation of the gamma-carboxyglutamic acid domain of urinary prothrombin fragment 1 from renal parenchyma was detected by polymerase chain reaction-single strand conformational polymorphism sequencing. The gamma-carboxyglutamic acid composition of urinary prothrombin fragment 1 was significantly decreased from normal (24.4 to 1.7 mol/1,000 amino acids) in patients with calcium oxalate calculus. The mean growth index +/- SD of urinary prothrombin fragment 1 to calcium oxalate crystals was 42.3 +/- 4.2 compared with the normal index of 19.2 +/- 2.8 (p <0.01). The polymerase chain reaction-single strand conformational polymorphism sequencing technique revealed no genetic mutation of the gamma-carboxyglutamic acid domain of urinary prothrombin fragment 1 in patients with calcium oxalate calculus. The gamma-carboxyglutamic acid composition of urinary prothrombin fragment 1 as well as its ability to inhibit calcium oxalate crystal growth was significantly decreased in patients with calcium oxalate calculus. This was not caused by genetic mutation of the gamma-carboxyglutamic acid domain of urinary prothrombin fragment 1. It is important to elucidate the mechanisms of calcium oxalate stones in view of urinary prothrombin fragment 1.

Modulators of urinary stone formation.

Urine contains compounds that modulate the nucleation, growth and aggregation of crystals as well as their attachment to renal epithelial cells. These compounds may function to protect the kidneys against: 1, the possibility of crystallization in tubular fluid and urine, which are generally metastable with respect to calcium salts, 2, crystal retention within the kidneys thereby preventing stone formation and 3, possibly against plaque formation at the nephron basement membrane. Since oxalate is the most common stone type, the effect of various modulators on calcium oxalate (CaOx) crystallization has been examined in greater details. Most of the inhibitory activity resides in macromolecules such as glycoproteins and glycosaminoglycans while nucleation promotion activity is most likely sustained by membrane lipids. Nephrocalcin, Tamm-Horsfall protein, osteopontin, urinary prothrombin fragment 1, and bikunin are the most studied inhibitory proteins while chondroitin sulfate (CS), heparan sulfate (HS) and hyaluronic acid (HA) are the best studied glycosaminoglycans. Crystallization modulating macromolecules discussed here are also prominent in cell injury, inflammation and recovery. Renal epithelial cells on exposure to oxalate and CaOx crystals produce some of the inflammatory molecules such as monocyte chemoattractant protein-1 (MCP-1) with no apparent role in crystal formation. In addition, macrophages surround the CaOx crystals present in the renal interstitium. These observations indicate a close relationship between inflammation and nephrolithiasis.