Pooled genetic analysis in ultrasound measured non-alcoholic fatty liver disease in Indian subjects: A pilot study

AIM: To investigate genetic susceptibility in Indian subjects with non-alcoholic fatty liver disease (NAFLD) by performing a pooled genetic study.

METHODS: Study subjects (n = 306) were recruited and categorized into NAFLD and control groups based on ultrasound findings of fatty infiltration. Of the 306 individuals, 156 individuals had fatty infiltration and thus comprised the NAFLD group. One hundred and fifty (n = 150) individuals were normal, without fatty infiltration of the liver, comprising the control group. Blood samples, demographic and anthropometric data from the individuals were collected after obtaining informed consent. Anthropometric data, blood glucose, lipids and liver function tests were estimated using standard methods. Genome wide association studies done to date on NAFLD were identified, 19 single nucleotide polymorphisms (SNPs) were selected from these studies that were reported to be significantly associated with NAFLD and genotyping was performed on the Sequenom platform. Student’s t test for continuous variables and χ² test was applied to variant carriers from both groups. Required corrections were applied as multiple testing was done.

RESULTS The mean age of the control group was 39.78 ± 10.83 and the NAFLD group was 36.63 ± 8.20 years. The waist circumference of males and females in the control and NAFLD groups were 80.13 ± 10.35; 81.77 ± 13.65 and 94.09 ± 10.53; 92.53 ± 8.27 cms respectively. The mean triglyceride and alanine transaminase (ALT) levels in the control and NAFLD groups were 135.18 ± 7.77 mg/dL; 25.39 ± 14.73 IU/L and 184.40 ± 84.31 mg/dL; 110.20 ± 67.05 IU/L respectively. When χ² test was applied to the number of individuals carrying the variant risk alleles between the control and NAFLD group, a significant association was seen between rs738409 of the patatin-like phospholipase domain containing 3 (PNPLA3) gene (P = 0.001), rs2073080 of the PARVB gene (P = 0.02), rs2143571 of SAMM50 gene (P = 0.05) and rs6487679 of the pregnancy zone protein (PZP) gene (P = 0.01) with the disease. Variant single nucleotide polymorphisms (SNPs) in NCAN and PNPLA3 gene were associated with higher levels of ALT, whereas variant SNPs in APOC3, PNPLA3, EFCAB4B and COL13A1 were associated with high triglyceride levels. Apart from the above associations, rs2073080, rs343062 and rs6591182 were significantly associated with high BMI; rs2854117 and rs738409 with high triglyceride levels; and rs2073080, rs2143571, rs2228603, rs6487679 and rs738409 with high ALT levels.

CONCLUSION: Pooled genetic analysis revealed an association of SNPs in PNPLA3, PARVB, SAMM50 and PZP genes with NAFLD. SNPs in NCAN and PNPLA3 gene were associated with higher levels of ALT, whereas variant SNPs in APOC3, PNPLA3, EFCAB4B and COL13A1 were associated with high triglyceride levels.

Stability and normal incidence reflectivity of W/B4C multilayer mirror near the boron K absorption edge

A multilayer structure consisting of alternate layers of W and B4C has been deposited using a magnetron sputtering system. The structure of the as-deposited and vacuum-annealed W/B4C multilayer sample has been characterized using grazing incidence x-ray reflectivity, grazing incidence diffraction, and the normal incidence reflectivity has been measured using synchrotron radiation. A two-layer model consisting of tungsten and boron carbide is presented. The multilayer structure was found to be stable after 800°C annealing. Grazing incidence x-ray diffraction measurements suggested that W is polycrystalline with small grain size. No signature of tungsten carbide or tungsten boride formation could be observed during the annealing treatments. A near normal incidence soft x-ray reflectivity (SXRR) of ~8.3% was obtained at 6.8 nm wavelength. A little drop (~1%) in SXRR after 800°C annealing suggested that there were no compositional changes within the layers during the annealing treatments.

Reduced Expression of Human Chemokine Genes RANTES and IP-10 in Hepatitis B Virus Mediated Cirrhosis of Liver

Regulated upon Activation Normal T cell Expressed and Secreted (RANTES) and interferon gamma inducible protein 10 (IP-10), both chemokines are chemotactic for immunocompetent cells and play an important role in cell mediated antiviral defense. The objective of this work was to assess the expression pattern of RANTES and IP-10 genes in peripheral blood mononuclear cells (PBMCs) of hepatitis B virus (HBV) infected patients having various disease severity. The study was performed on 79 HBV infected patients grouped into acute, inactive carriers (IC), chronic (CHB), cirrhosis and hepatocellular carcinoma (HCC) plus 41 healthy voluntary blood donors as controls. Quantification of HBV surface antigen (HBsAg) was done by a sandwich enzyme linked immunosorbent assay (ELISA). Conventional and real time polymerase chain reaction (PCR) were used for genotyping and determination of HBV DNA load respectively. RANTES and IP-10 mRNA expressions were evaluated by reverse transcription PCR (RT-PCR) and densitometry. Results obtained show that RANTES expression reduced significantly (p<0.0001) in cirrhosis group in comparison to controls and remain unaltered in other disease categories. Reduction in IP-10 expression was significant (p=0.006) in patients of all disease categories than controls which was most evident in cirrhosis group (p<0.0001). No association was found between the expression level of chemokines with HBV genotypes, HBsAg and HBV DNA levels in sera.It could be concluded that reduced expression of both the chemokines might be associated with lesser infiltration of immunocompetent cells to liver to avert further damage in cirrhosis.Serum level of both RANTES and IP-10 can be considered as prognostic marker of liver cirrhosis by validation studies.

The Distribution of Genotype and Allelic Frequency of IL28B Gene Polymorphism in Andhra Pradesh, India

BACKGROUND

The single nucleotide polymorphism (SNP) of IL28B gene on chromosome 19, encoding for the interferon (IFN)-λ-3 is strongly associated with treatment response to pegylated-IFN and ribavirin in patients infected with different genotypes of hepatitis C virus (HCV). Difference between ethnicity and treatment response rates suggesting a key role of host genetics. The IL28B polymorphism (rs12979860C/T) shows a marked differential distribution between racial groups.

AIM

The present study is aimed to evaluate genotype and allelic frequency of IL28B gene polymorphism (rs12979860C/T) in Andhra Pradesh, India.

METHODS

A total of 220 healthy controls were recruited for the study. The genotyping of SNP rs12979860C/T on IL28B gene was performed by polymerase chain reaction-direct sequencing method.

RESULT

The frequency of CC genotype was found to be significantly (59.09%) higher compared to CT (34.09%) and TT (6.81%) genotypes, respectively. The frequency of major allele C is 0.762 whereas minor allele T is 0.238.

CONCLUSION

The higher distribution of genotype 'CC' of SNP, rs12979860C/T of IL28B gene in study subjects is suggestive of better response of HCV patients to standard anti-HCV therapy.

Identification of circulating CD90 CD73 cells in cirrhosis of liver

AIM

To identify circulating CD90(+) CD73(+) CD45(-) cells and evaluate their in vitro proliferating abilities.

METHODS

Patients with cirrhosis (n = 43), and healthy volunteers (n = 40) were recruited to the study. Mononuclear cells were isolated and cultured from the peripheral blood of controls and cirrhosis patients. Fibroblast-like cells that appeared in cultures were analyzed for morphological features, enumerated by flow cytometry and confirmed by immunocytochemistry (ICC). Colony forming efficiency (CFE) of these cells was assessed and expressed as a percentage.

RESULTS

In comparison to healthy volunteers, cells obtained from cirrhotic patients showed a significant increase (P < 0.001) in the percentage of CD90(+) CD73(+) CD45(-) cells in culture. Cultured cells also showed 10 fold increases in CFE. Flow cytometry and ICC confirmed that the proliferating cells expressed CD90(+) CD73(+) in the cultures from cirrhosis patients.

CONCLUSION

These results indicate the presence of circulating CD90(+) CD73(+) CD45(-) cells in patients with liver cirrhosis that have the potential to proliferate at a higher rate.

A case-control study on nutritional risk factors in non-alcoholic fatty liver disease in Indian population

BACKGROUND/OBJECTIVES

Non-alcoholic fatty liver disease (NAFLD) is considered an integral part of metabolic syndrome (MS). We aimed to explore the inter-relations of MS and dietary composition in subjects with and without hepatic steatosis and to identify the nutritional risk factors contributing to NAFLD.

SUBJECTS/METHODS

In all 98 subjects with steatosis and 102 controls were selected for the study after screening 260 consecutive healthy individuals. Anthropometric and nutritional information, biochemical data and clinical profile were analyzed. Prevalence of MS was determined based on the consensus statement for diagnosis of MS for Asian Indians. Multiple logistic regression analysis was done to predict the dietary risk factors in NAFLD.

RESULTS

Prevalence of MS was 44.9% among NAFLD cases and 25.5% among controls (P=0.003). Subjects with NAFLD had significantly higher values of body mass index (BMI), waist circumference (WC), percent body fat, total cholesterol, triglycerides and blood pressure than controls. The total calorie intake, percent of carbohydrate and fat intake of NAFLD cases was significantly higher than controls. Multiple logistic regression analysis showed BMI (odds ratio 6.03 (95% confidence interval 3.26-11.14)), WC (5.49 (2.59-11.57)) and percent dietary fat intake (2.51 (1.99-3.31)) as independent nutritional risk factors in NAFLD.

CONCLUSIONS

In this study, there is a high prevalence of MS among subjects with steatosis and metabolic disorders were closely related to NAFLD. BMI, WC and percent fat intake are independent dietary risk factors in NAFLD. Decreased nutritional intake with restricted fat may constitute an important therapy in subjects with NAFLD.

Hydrogeochemical characterization of fluoride rich groundwater of Wailpalli watershed, Nalgonda District, Andhra Pradesh, India

The groundwater of Nalgonda district is well known for its very high fluoride content for the past five decades. Many researchers have contributed their scientific knowledge to unravel causes for fluoride enrichment of groundwater. In the present paper, an attempt has been made to relate the high fluoride content in the groundwater to hydrogeochemical characterization of the water in a fracture hard rock terrain--the Wailpally watershed. Groundwater samples collected from all the major geomorphic units in pre- and post-monsoon seasons were analyzed for its major ion constituents such as Ca(2+), Mg(2+), Na(+), K(+), CO3-, HCO3-, Cl(-), SO4(-2), NO3-, and F(-). The groundwaters in the watershed have the average fluoride content of 2.79 mg/l in pre-monsoon and 2.83 mg/l in post-monsoon. Fluoride concentration in groundwater does not show perceptible change neither with time nor in space. The ionic dominance pattern is in the order of Na(+) > Ca(2+) > Mg(2+) > K(-) among cations and HCO3- Cl(-) > SO4(-2) NO3- F(-) among anions in pre-monsoon. In post-monsoon, Mg replaces Ca(2+) and NO3- takes the place of SO4(-2). The Modified Piper diagram reflect that the water belong to Ca(+2)-Mg(+2)-HCO3- to Na(+)-HCO3- facies. Negative chloralkali indices in both the seasons prove that ion exchange between Na(+) and K(+) in aquatic solution took place with Ca(+2) and Mg(+2) of host rock. The interpretation of plots for different major ions and molar ratios suggest that weathering of silicate rocks and water-rock interaction is responsible for major ion chemistry of groundwater in Wailpally watershed. Chemical characteristics and evolution of this fluoride-contaminated groundwater is akin to normal waters of other hard rock terrain; hence, it can be concluded that aquifer material play an important role in the contribution of fluoride in to the accompanying water. High fluoride content in groundwater can be attributed to the continuous water-rock interaction during the process of percolation with fluoride-bearing country rocks under arid, low precipitation, and high evapotranspiration conditions.

Relationship between serum HBsAg level, HBV DNA level, and peripheral immune cells in patients with chronic hepatitis B virus infection

BACKGROUND

The chronicity of hepatitis B virus (HBV) infection is attributed to inappropriate functioning of cell-mediated immunity. Besides the importance of measuring serum HBV DNA and HBV surface antigen (HBsAg) as markers of viral replication and exposure, respectively, studies regarding their influence on immune cell status in chronic HBV infection are still scarce. Because such studies of chronic HBV patients have not been reported for India, we attempted to evaluate the relationship between serum concentrations of HBsAg, HBV DNA, and percentage of immune cells in peripheral blood of Indian subjects with chronic HBV infection.

METHODS

Thirty-one HbsAg-positive subjects were evaluated for serum HBe antigen (HBeAg), anti-HBe, and alanine transferase status by standard enzyme-linked immunosorbent assay (ELISA) and biochemical procedures. Serum HBV DNA level was determined by real-time TaqMan® polymerase chain reaction assay. Serum HBsAg level was measured by a third-generation sandwich ELISA kit. Peripheral immune cell profiling was done by multifluorometric flow cytometry analysis, for which 21 healthy subjects were included as controls.

RESULTS

The majority (93.5%) of the study subjects were HBeAg-negative and anti-HBeAg-positive. Mean viral load, HBsAg, and alanine transferase levels were 4.20 ± 1.96 log copies/mL, 5.98 ± 4.62 log IU/mL, and 74.5 ± 110 IU/mL, respectively. In comparison with controls, total T cell and cytotoxic T cell populations were significantly (P < 0.05) reduced in HBV-infected subjects, while the status of B cells, natural killer cells, T helper cells, and ratio of T helper to cytotoxic cells remained unaltered.

CONCLUSION

Suppression of the peripheral cytotoxic T cell population in chronic HBeAg-negative chronic HBV infection is influenced by increased viral load. Serum HBsAg concentration appeared independent of serum HBV DNA level and immune cell status. Nonelevation of natural killer cell and T helper cell numbers in subjects harboring lower to moderate HBV loads is further indicative of noninduction of innate as well as a coordinated adaptive immune response favoring chronicity of the disease.

Optical properties of indium phosphide in the 50-200 Å wavelength region using a reflectivity technique

The optical constants of indium phosphide (InP) in the soft x-ray region of 50-200 Å are determined from angle-dependent reflectivity measurements. The measurements are carried out using the reflectivity beam line at the Indus-1 synchrotron source. The derived optical constants are compared with tabulated values of Henke et al. [At. Data Nucl. Data Tables 54, 181 (1993)]. Experimental values of δ and β are in close agreement with the tabulated values in the lower wavelength region of 50-120 Å. The experimental value indicates an edge shift of 0.4 Å toward the lower wavelength side from the phosphorous L-edge value of 92 Å. However, above the 120 Å region, where the indium N(2) edge falls at 160.7 Å, there is a huge difference between experimental and tabulated values. Both delta and beta values are significantly higher. In contrast to tabulated values of the β/δ ratio, which is more than 1 above the 140 Å region, the experimental measured ratio is found to be less than 1. This study presents the first reported experimental values of optical constants for InP in this wavelength range, to the best of our knowledge.

Recurrent inversion events at 17q21.31 microdeletion locus are linked to the MAPT H2 haplotype

The chromosomal band 17q21.31, containing the microtubule-associated protein tau (MAPT) gene, is a hotspot for chromosomal rearrangements. It is known to contain a common inversion polymorphism of approximately 900 kb in populations with European ancestry. The inverted configuration is linked to a distinct MAPT haplotype, H2, which is relatively common in Europeans but nearly absent in Asian and African populations. Recent studies have demonstrated that the H2 haplotype is ancestral in hominoids, and under positive selection in Europeans. This haplotype is also linked to events leading to the 17q21.31 microdeletion syndrome, one of the most common causes of 'idiopathic' mental retardation in people of European descent. We performed direct analysis of the chromosome structure by fluorescence in situ hybridization and observed heterozygosity of the inversion status for the H2 chromosomes, but not for the H1 haplotype. Inversion heterozygosity was also observed in a mother homozygous for the H2 haplotype, who transmitted the chromosome with the deletion to a proband with 17q21.31 microdeletion syndrome. Our results highlight an allele-specific sensitivity to chromosome rearrangements and suggest that it is the heterozygosity of inversion status that predisposes to the 17q21.31 microdeletion syndrome.

Death from metastatic donor-derived ovarian cancer in a male kidney transplant recipient

Posttransplant malignancy developing in an allograft is an uncommon complication of organ transplantation. The tumor may represent malignant transformation of donor or recipient cells that were previously normal, metastatic malignancy of recipient origin or malignancy transmitted from organ donor to recipient. Establishing the origin of the malignancy is critical to treatment algorithms. It is generally believed allograft removal and immunosuppression withdrawal will lead to resolution of transmitted malignancies in cases where the renal allograft is the origin. We report a male patient who developed metastatic ovarian malignancy secondary to donor transmission.

Genome evolution in the mosquitoes and other closely related members of superfamily Culicoidea

Karyotypes and nuclear DNA amounts of 36 species belonging to twelve genera of mosquitoes and other closely related taxa in the superfamily Culicoidea (Dixidae, Chaoboridae, and Culicidae) were studied. The results showed an eight-fold range in haploid DNA amounts and a 4.5-fold range in total chromosomal lengths. It is concluded that the evolutionary trend in this superfamily has been an overall increase in total haploid DNA amounts from the primitive Dixidae to the highly evolved Culcidae, with a concomitant increase in overall chromosome sizes.

Effects of Inositol Hexaphosphate (Phytate) on Calcium Binding, Calcium Oxalate Crystallization and In Vitro Stone Growth

PURPOSE

We measured and compared 3 activities of inositol hexaphosphate, also known as phytate, to explore their importance in relation to antilithogenic potential.

MATERIALS AND METHODS

Calcium binding activity by inositol hexaphosphate was measured with a calcium electrode in artificial and whole urine. Calcium oxalate crystallization inhibition was measured by a 96-well plate turbidimetric method with artificial and whole urine. Effects on stone growth were measured in an in vitro system of 12 stones grown simultaneously (a stone farm) using artificial urine alone or supplemented with urinary macromolecules.

RESULTS

Phytate decreased ionized calcium, increased the metastable limit, decreased the crystallization turbidity rate index and decreased the in vitro stone growth rate. The effective concentration for calcium binding reduction was about 2 orders of magnitude higher than that required for crystallization inhibition, which in turn was about 2 orders of magnitude higher than that required for stone growth inhibition. When human urine or artificial urine supplemented with urinary macromolecules was used, the effective concentration of phytate for inhibiting crystallization and stone growth was increased by about 1 order of magnitude.

CONCLUSIONS

Inhibition of crystallization by phytate does not depend on decreasing the effective ionized calcium concentration and inhibition of in vitro stone growth does not depend on inhibiting crystallization of the suspended crystals. To our knowledge this is the first demonstration of a quantitative distinction between the inhibition of crystallization and stone growth. Inhibition of in vitro stone growth in the presence of macromolecules occurred at concentrations consistent with urinary phytate excretion.

Duplication 8q22.1-q24.1 associated with bipolar disorder and speech delay

OBJECTIVE

To report a case of a child with bipolar disorder found to have an unbalanced translocation involving the long arm of chromosome 8, a region that has been previously implicated in genome-wide linkage scans.

CASE REPORT

A 7-year-old boy with a complex psychiatric symptom presentation including attention deficits, distractibility, impulsivity, pressured speech, sleep disturbance, aggressive behavior, and hypersexuality diagnosed with bipolar disorder. He also showed evidence of borderline intellectual and adaptive functioning and had mild dysmorphic features with a duplication of distal 8q that arose as an unbalanced chromosomal translocation due to a maternal 15p;8q insertion.

CONCLUSION

This finding of an unbalanced translocation provides further evidence to support previous linkage studies of a potential causative gene on 8q for bipolar disorder.

The association of different urinary proteins with calcium oxalate hydromorphs. Evidence for non-specific interactions

It has been proposed that various urinary proteins interact specifically with different calcium oxalate hydromorphs and these interactions have important implications regarding the understanding of the onset and progress of kidney stone disease. Calcium oxalate monohydrate and dihydrate crystals were grown and characterised thoroughly to establish sample purity. These crystals were then incubated in artificial urine samples containing isolated urinary macromolecules. Crystal growth was prevented by saturating the incubation mix with calcium oxalate, and this was confirmed through electron microscopy and calcium measurements of the incubation mix. The surface interactions between the different calcium oxalate hydrates and urinary proteins were investigated by the use of Western blots and immunoassays. The same proteins, notably albumin, Tamm-Horsfall protein, osteopontin and prothrombin fragment 1, associated with both hydrates. There was a trend for more protein to associate with calcium oxalate dihydrate, and greater quantities of different proteins associated with both hydrates when Tamm-Horsfall protein was removed from the incubation mix. There is no evidence from this study to indicate that particular proteins interact with specific calcium oxalate hydrates, which in turn suggests that these protein-mineral interactions are likely to be mediated through non-specific charge interactions.

Imaging for kidney stones

Imaging investigations play a vital role in the management of patients with kidney stones. The techniques available include plain x-ray of the abdomen, ultrasound scan, intravenous urogram, computed tomography (CT) and magnetic resonance imaging, amongst others. All of these techniques have their own individual roles to play and also have limitations. CT has been establishing itself as the imaging technique of choice and some exciting developments are on the way. However, renal stone disease is a complex condition. Furthermore, there are a variety of surgical techniques used to treat stones. It is therefore important that the strengths and weakness of each of the modalities are clearly understood and the investigations are tailored to address the problem in hand.

A stone farm: development of a method for simultaneous production of multiple calcium oxalate stones in vitro

We have previously shown how individual calcium oxalate stones of about 1 cm can be grown in vitro. While this proved a design concept, it was severely limited as an experimental tool because of the time required to undertake comparative studies. Here we describe a development of this system in which six parallel pairs of stone generators are supplied with feed solutions generating a medium that is supersaturated with calcium oxalate. Twelve stones were grown simultaneously in aseptically prepared artificial urine over a period of 32 days from 100 mg to about 250 mg. Flow rates, pH and [Ca(2+)] were stable and reproducible over the course of the experiment. Sodium azide (0.02%) was included in the growth medium of six stones and caused a modest decrease in growth rate from 5.5 to 3.4 mg/day. The experimental design is such that this was readily detectable both visually and statistically ( p<0.001). This multiple stone growing system ("a stone farm") shows improved consistency and illustrates the statistical power of the technique. Azide has only a minor effect on the growth kinetics and can be used as an antibacterial agent in studies involving urinary macromolecules. The technique is suitable for practical and meaningful investigation of calcium oxalate stone formation in vitro.

Effect of cyclooxygenase-2 (COX-2) inhibitors on prostate cancer cell proliferation

BACKGROUND

The tricyclic cyclooxygenase-2 (COX-2) inhibitors celecoxib and rofecoxib exhibit different magnitudes of antiproliferative activity against the human prostate cancer cell lines LNCaP and PC-3. We investigated the correlation between the COX-2 inhibitory potencies, antiproliferative activities and the nature of the central ring system of novel tricyclic COX-2 inhibitors belonging to the diarylcycloalkyl and diarylheterocyclic classes possessing a central 3-membered cyclopropyl (1 and 2), a 5-membered isoxazoline (3), an isoxazole (4) or 2-(5H) furanone (5), and a 6-membered pyran-2-one (6a-c) ring system.

MATERIALS AND METHODS

Novel tricyclics were synthesized and evaluated in vitro for their COX-1/COX-2 inhibitory activities and their abilities to inhibit cell proliferation in prostate (AT3B-1, PC-3 and LNCaP) and breast (MCF-7) cancer cell lines. A molecular modeling study was carried out to characterize the electronic nature of the central ring systems of the novel tricyclic COX-2 inhibitors.

RESULTS

The isoxazoline (3), which exhibited excellent COX-2 inhibitory potency and selectivity, showed growth inhibition in all the cell lines tested with IC50 values of 349 microM (AT3B-1), 378 microM (PC-3), 100 microM (LNCaP) and 200 microM (MCF-7), respectively. The rofecoxib analog (5) and 6-membered pyran-2-ones (6a-c) showed weak inhibition (MCF-7, AT3-B-1 and PC-3) inspite of possessing good COX-2 inhibitory potencies and selectivities.

CONCLUSION

This study demonstrates that the antiproliferative activity profiles exhibited by the novel tricyclic COX-2 inhibitors is dependent on the electronic nature of the central ring system and is independent of their COX-2 inhibitory potencies and selectivities. Accordingly, the 2,3-dimethyl-5-(4-methylsulfonylphenyl)-4-phenyl-4-isoxazoline (3), which possesses an electron rich central 5-membered isoxazole ring, could serve as a lead compound to develop novel drugs to treat prostate cancer.

Pulse therapy and its modifications in pemphigus: a six year study

BACKGROUND

Dexamethasone-cyclophosphamide pulse (DCP) therapy for the pemphigus group of disorders is being widely used in India after its introduction in 1986. However, there are certain limitations to its application due to the serious side effects of cyclophosphamide.

METHODS

Between 1995 and 2001, we treated 41 patients of pemphigus with modified pulse therapy. These modifications included certain changes in the DCP therapy protocol and substitution of cyclophosphamide with either azathioprine or methotrexate in a few patients.

RESULTS

We observed a good response to pulse therapy in all 34 patients who took treatment regularly.

CONCLUSIONS

We found the modifications to the original DCP therapy protocol to be very effective and useful.

Enlargement of calcium oxalate stones to clinically significant size in an in-vitro stone generator

OBJECTIVE

To develop and validate an in vitro method suitable for the quantitative investigation of the growth of calcium oxalate stones through to a clinically significant size.

MATERIALS AND METHODS

Small fragments of calcium oxalate calculi were suspended in a mixed suspension/mixed product removal crystalliser supplied with artificial urine supersaturated with calcium oxalate. The fragments were weighed at regular intervals until they reached approximately equal 500 mg. The results were plotted as weight against time and fitted to equations corresponding to constant increase in diameter, surface area-controlled and constant-deposition growth patterns. The choice of the most appropriate model was based on the squared regression coefficient (r2).

RESULTS

Eight fragments (2-6 mm in diameter) were grown to approximately 10 mm in diameter over periods from 137 to 369 h. Seven of the growth curves were best-fitted (r2 > or = 0.988) by the equation w = kt(3/2) + c, where w is the weight, k is a growth constant, t is the time and c is a constant approximating to the initial weight. This corresponds to a surface area-dependent mechanism.

CONCLUSIONS

The growth of these small fragments to a clinically significant size accelerated throughout the experimental period in a way which was consistent with a surface area-dependent mechanism. We have developed a resilient model suitable for studying the kinetics of calcium oxalate stone growth in vitro.