Biomedical subjects

S R Khan

Publications and source records attributed to S R Khan.

At least 37 records · Page 2Linked to original sources

PubMed2000

In vivo activity of a PSA-activated doxorubicin prodrug against PSA-producing human prostate cancer xenografts.

BACKGROUND: There is currently no effective therapy for men with metastatic prostate cancer who relapse after androgen ablation. Prolonged administration of effective concentrations of standard chemotherapeutic agents is usually not possible because of dose-limiting systemic toxicities. A new strategy to target cytotoxic agents specifically to sites of metastatic prostate cancer while avoiding systemic toxicity would be to develop prodrugs that are inactive when given systemically but become activated when processed proteolytically within prostate cancer metastases by prostate-specific antigen (PSA). In this study, the in vivo activity of a prodrug consisting of doxorubicin (Dox) conjugated to a PSA-specific peptide carrier is described. METHODS: Nude mice bearing PSA-producing human prostate cancer xenografts were treated either intraperitoneally (IP) or by continuous infusion with the Dox prodrug. Toxicity (weight loss, death) and antitumor efficacy (tumor volume changes) were determined. RESULTS: The PSA-peptide Dox prodrug had no discernible systemic toxicity when given at four times the 100% lethal Dox equivalent dose. An IP dose of 60 mg/kg/week x 4 weeks resulted in a 57% decrease in tumor weight vs. control after 40 days. A 25 mg/kg/week dose given by continuous infusion produced a similar decrease in tumor weight vs. control. CONCLUSIONS: The PSA-specific peptide/doxorubicin prodrug can be used to deliver higher intratumoral levels of Dox for longer duration while avoiding systemic toxicity. In addition, these results validate the specificity of the PSA-specific peptide as a targetable drug carrier. This PSA-specific peptide could also be used as a carrier to target a wide variety of cytotoxic agents for specific activation within sites of metastatic prostate cancer.

Animals↗

PubMed2000

Membranes and their constituents as promoters of calcium oxalate crystal formation in human urine.

We have proposed that membranes of cellular degradation products are a suitable substrate for the nucleation of calcium oxalate (CaOx) crystals in human urine. Human urine is generally metastable with respect to CaOx. To demonstrate that cellular membranes present in the urine promote nucleation of CaOx we removed these substrates by filtration or centrifugation and induced crystallization by adding sodium oxalate, before and after filtration or centrifugation. In a separate experiment, membrane vesicles isolated from rat renal tubular brush border were added into the filtered or centrifuged urine before crystal induction. Crystals were counted using a particle counter. Urine, the pellet, and retentate were analyzed for the presence of membranes, lipids, and proteins. Lipids were further separated into different classes, identified, and quantified. Both filtration and centrifugation removed lipids, proteins, and membrane vesicles, causing a reduction in lipid and protein contents of the urine. More crystals formed in whole than in filtered or centrifuged urine. The number of crystals significantly increased when filtered urine was supplemented with various urinary components such as the retentate and phospholipids, which are removed during filtration. We also determined the urinary metastable limit with respect to CaOx. Filtration and centrifugation were associated with increased metastable limit which was reduced by the addition of membrane vesicles. These results support our hypothesis that urine normally contains promoters of CaOx crystal formation and that membranes and their constituents are the most likely substrate for crystal nucleation in the urine.

Animals↗

PubMed2000

Effects of an extract from Herniaria hirsuta on calcium oxalate crystallization in vitro.

OBJECTIVE: To evaluate the effectiveness of an extract obtained from Herniaria hirsuta on calcium oxalate crystallization in vitro. Materials and methods An extract was prepared from H. hirsuta at different concentrations (0.0625-1 mg/mL). Crystallization was induced in whole normal human urine samples in the absence or presence of the extract. Crystals generated in the urine were harvested and analysed by scanning electron microscopy. The nucleation and aggregation of calcium oxalate crystals were measured separately using spectrophotometric methods. The nucleation rate was followed at 620 nm after mixing calcium chloride and sodium oxalate solution at 37 degrees C, with stirring. The induction time in the presence of herb extract was compared with that of the control. The aggregation rate was also followed at 620 nm in a buffered solution containing calcium oxalate monohydrate crystals after stopping the stirring. The rate was evaluated by comparing the slope of turbidity in the presence of the extract with that of the control. RESULTS: The herb extract promoted the precipitation of calcium oxalate particles in whole urine. SEM showed that there were more crystals with increasing concentration of extract but that they were proportionally smaller. Moreover, the presence of herb extract favoured the formation of calcium oxalate dihydrate rather than monohydrate crystals. The extract inhibited calcium oxalate crystal aggregation. In an independent experiment, the herb extract was dialysed and filtered before inducing crystallization, to eliminate any fibrous particles and oxalate. The treated herb extract promoted more crystallization, especially at high concentrations. CONCLUSION: An extract of H. hirsuta promoted the nucleation of calcium oxalate crystals, increasing their number but decreasing their size. It also promoted the formation of calcium oxalate dihydrate crystals, despite the presence of calcium oxalate monohydrate particles. The extract may contain substances that inhibit calcium oxalate crystal aggregation. These properties of H. hirsuta might be beneficial in preventing kidney stone formation.

Calcium Oxalate↗

PubMed2000

Free radical scavengers, catalase and superoxide dismutase provide protection from oxalate-associated injury to LLC-PK1 and MDCK cells.

PURPOSE: Current studies have provided evidence that exposure of renal epithelial cells to oxalate and calcium oxalate crystals induces lipid peroxidation and injures the cells. Since oxidant/antioxidant balance is likely to play a critical role, we determined the effect of antioxidant scavengers on production of free radicals and injury to LLC-PK1 and MDCK cells from exposure to oxalate (Ox) or Ox + calcium oxalate monohydrate (COM) crystals. MATERIALS AND METHODS: LLC-PK1 and MDCK cells were grown in monolayers and exposed to 1.0 mmol. Ox or 1.0 mmol. Ox + 500 microg. /ml. COM crystals for 120 or 240 minutes. We measured the release of lactate dehydrogenase (LDH) as a marker for cell injury and malondialdehyde (MDA) as a marker of lipid peroxidation. Superoxide and hydroxyl radicals were measured in the presence or absence of 400 U/ml. catalase, or superoxide dismutase (SOD). RESULTS: Exposure of LLC-PK1 cells to Ox resulted in a significant increase in MDA and release of LDH, which was further elevated when COM crystals were added. MDCK cells responded similarly to both challenges, but showed significantly less impact when compared with LLC-PK1 cells. Both treatments were associated with significant increase in the generation of hydroxyl and superoxide radicals by both cell types. In both cell lines, the addition of catalase or SOD significantly reduced the increase of MDA and release of LDH. CONCLUSIONS: Results of the present study indicate that both Ox and COM crystals are injurious to renal epithelial cells and the injury is associated with generation of free radicals. Cells of proximal tubular origin are more susceptible than those of distal tubules and collecting ducts. Free radical scavengers, catalase and SOD provide significant protection.

Animals↗

PubMed2000

Changes in urine macromolecular composition during processing.

PURPOSE: To determine the urinary crystallization inhibitory activity, urine is generally centrifuged and/or filtered. These preparative procedures may result in a total or partial removal of many macromolecular constituents implicated in crystallization. The main purpose of this study was to investigate the changes in urinary macromolecular composition following centrifugation and filtration. MATERIALS AND METHODS: Twenty-four hour urine samples were collected from human volunteers. Each was divided into 4 aliquots; one was filtered, the other was centrifuged, another was centrifuged and filtered. The control sample was neither filtered nor centrifuged. Total protein and lipid contents of each sample were determined. Proteins were analyzed using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Western blot analysis was performed using antibodies against osteopontin (OPN), prothrombin (PT) related proteins, inter-alpha-inhibitor (IalphaI) related proteins, Tamm-Horsfall protein (THP), and albumin (ALB). The effect of processing on incorporation of urinary proteins in crystal matrices was also examined. Calcium oxalate crystals were produced in processed and unprocessed urine samples by the addition of sodium oxalate. Crystals were harvested, de-mineralized and their proteins analyzed by SDS-PAGE and Western blotting. RESULTS: Processing reduced the amounts of both proteins and lipids in the urine. Previously we identified phospholipids in the matrix of calcium oxalate crystals as well as the filtrate and retentate removed during filtration and centrifugation. Phospholipids have a high affinity for calcium-containing crystals. In the case of proteins, those with high molecular weights appeared to be clearly affected by filtration and centrifugation. Processing also appeared to influence the incorporation of proteins in the crystals. The matrix of crystals produced in processed urine contained less THP than those made in unprocessed urine, apparently a result of the loss of this higher molecular weight protein during processing. Incorporation of PT-related proteins, particularly fragment 1, was increased. CONCLUSIONS: We propose that selective inclusion of macromolecules is a result of an increase in available binding sites on crystal surfaces because of the removal of certain calcium binding substances such as phospholipids and proteins. Removal of larger macromolecules from the milieu may also provide a better access to the crystal surfaces.

Centrifugation↗

PubMed2000

Nephrolithiasis: a consequence of renal epithelial cell exposure to oxalate and calcium oxalate crystals.

PURPOSE: Formation of calcium oxalate (CaOx) kidney stones was investigated using three approaches. MATERIALS AND METHODS: Pathogenesis of crystalluria and crystal deposition in the kidneys was examined in vivo by inducing hyperoxaluria in rats. Cultures of LLC-PK1 and MDCK cells were exposed to oxalate (Ox) and CaOx crystals to examine the effect on cells in various sections of the renal tubules. The nucleation potential of various substrates was examined by incubating them in metastable solutions of CaOx. RESULTS: Calcium oxalate crystals and nonphysiologic levels of Ox were injurious to renal epithelial cells. To combat these nephrotoxins, renal epithelial cells produce a variety of macromolecules such as bikunin and osteopontin, which are modulators of crystallization and may also be involved in crystal attachment to the cells. Sustained hyperoxaluria in association with CaOx crystals induced apoptosis as well as necrosis. Cellular degradation products induced heterogeneous nucleation of crystals at lower and physiologic levels of oxalate. They also promoted aggregation. CONCLUSIONS: Crystals begin to form in earlier segments of the nephron with a chance to grow and be retained in the collecting ducts after aggregation with other large crystals. Crystal deposits in the collecting ducts near the papillary surface, when exposed to the renal pelvic urine, become nidi for the development of kidney stones.

Animals↗

PubMed1999

Role of inter-alpha-inhibitor and its related proteins in urolithiasis. Purification of an inter-alpha-inhibitor related protein from the bovine kidney.

Urine contains several macromolecules that inhibit calcium oxalate (CaOx) crystallization. Among them is bikunin, the light chain of most of the inter-alpha-inhibitor (IalphaI) family of glycoproteins. This study aimed to verify whether bikunin and other members of the IalphaI family are synthesized in the kidneys or derived exclusively from the plasma. Proteins extracted from homogenized bovine kidney were applied successively to three chromatographic steps on DEAE-Sephacel, Sephacryl S-300, and Mono Q column. The inhibitory activity was assayed using a CaOx crystallization system. The presence of IalphaI-related proteins was determined by electrophoresis and Western blotting. The results showed that kidney extract contained a 125-kDa protein that cross-reacted with anti-IalphaI antibodies. This protein inhibited CaOx crystallization efficiently. According to its molecular weight and immunoreaction with anti-IalphaI antibody, the 125-kDa protein could be pre-alpha-inhibitor. The latter is known to encompass a heavy chain and bikunin, which may explain its inhibitory activity against CaOx crystallization. Consequently, we hypothesize that kidneys may produce some IalphaI-related proteins that are involved in the inhibition of stone formation.

Alpha-Globulins↗

PubMed1999

Role of inter-alpha-inhibitor and its related proteins in experimentally induced calcium oxalate urolithiasis. Localization of proteins and expression of bikunin gene in the rat kidney.

Our earlier studies indicated that members of the inter-alpha-inhibitor (IalphaI) family of glycoproteins may play an important role in urolithiasis. Indeed bikunin, the light chain of IalphaI is a potent inhibitor of calcium oxalate crystallization. In order to understand this role, the distribution of IalphaI and its related proteins, as well as the expression of bikunin, were studied in normal and nephrolithic rats. In normal rats, IalphaI immunoreactivity was located mainly in proximal tubules. However, in nephrolithic rats, in addition to proximal tubules, the staining was intensively extended to tubules in the corticomedullary junction. Furthermore, by using polymerase chain reaction technique, we demonstrated that gene encoding for bikunin was activated in kidneys of nephrolithic rats. We have previously demonstrated increased staining for osteopontin in association with calcium oxalate crystal deposition in rat kidneys. Others have shown an increase in osteopontin production by renal epithelial cells on exposure to calcium oxalate crystals. Based on these observations we conclude that kidney cells possess an auto-defense system against calcium oxalate crystallization and stone formation in which members of the IalphaI family may be closely involved.

Alpha-Globulins↗

PubMed1999

Temporal changes in mRNA expression for bikunin in the kidneys of rats during calcium oxalate nephrolithiasis.

Inter-alpha-inhibitor and other bikunin-containing proteins are synthesized in relatively large quantities by the liver. These proteins function as Kunitz-type serine protease inhibitors and appear capable of inhibiting calcium oxalate (CaOx) crystallization in vitro. Preliminary studies have shown that renal tubular epithelial cells synthesize bikunin in response to CaOx challenge. To examine this response in vivo, a sensitive reverse transcription-quantitative competitive template-PCR was developed to detect and quantify poly(A)+ -tailed bikunin mRNA expression in kidney tissue from normal rats and rats developing CaOx nephrolithiasis after challenge with ethylene glycol. Bikunin mRNA expression in rat liver tissue was assessed as a positive control. The expression of bikunin mRNA in liver did not differ significantly between normal control rats and experimental rats with induced hyperoxaluria and renal CaOx crystallization. In contrast, there were significant temporal increases in the levels of bikunin mRNA expression in rat kidneys during CaOx nephrolithiasis after challenge with ethylene glycol. Urinary excretion of bikunin-containing proteins seemed to increase concomitantly. These findings indicate an association between the induction of hyperoxaluria/CaOx nephrolithiasis and the expression of the bikunin gene in rat kidneys.

Alpha-Globulins↗

PubMed1999

Expression of bikunin mRNA in renal epithelial cells after oxalate exposure.

PURPOSE: To determine the changes in expression of bikunin in renal epithelial cells on exposure to oxalate and calcium oxalate crystals. MATERIALS AND METHODS: This study used reverse transcription polymerase chain reaction (RT-PCR) to examine bikunin mRNA expression levels in MDCK cells exposed to oxalate or calcium oxalate crystals. Poly(A)+ RNA was isolated directly from renal epithelial cells, then converted to cDNA with random primers and reverse transcriptase. To quantify the expression level ofbikunin mRNA, we developed a competitive DNA template for competitive PCR analysis. The PCR products were resolved by electrophoresis on 1.3% agarose gel and visualized with ethidium bromide. In this system, we could quantify the exact number of bikunin mRNA transcripts. Bikunin mRNA from rat liver was expressed as a positive control. RESULTS: Bikunin mRNAs and competitive templates from renal epithelial cells were expressed in all samples as 434 bp and 312 bp bands, respectively. Bikunin expression was significantly increased in oxalate exposed cells. Cells exposed to calcium oxalate monohydrate crystals or latex beads showed no significant change in expression of bikunin. Western blotting analysis also showed increased expression of bikunin and inter-alpha-inhibitor-related proteins in the culture medium of oxalate exposed cells. CONCLUSIONS: These findings suggest that renal epithelial cells express bikunin gene and have the capability to produce bikunin when stimulated by certain agents such as oxalate. This increased expression and production of bikunin may represent a protective response of renal epithelial cells to nephrotoxic challenges of oxalate.

Animals↗

PubMed1999

Direct correlation between hyperoxaluria/oxalate stone disease and the absence of the gastrointestinal tract-dwelling bacterium Oxalobacter formigenes: possible prevention by gut recolonization or enzyme replacement therapy.

Oxalobacter formigenes is a specific oxalate-degrading, anaerobic bacterium inhabiting the gastrointestinal tracts of vertebrates, including humans. This bacterium maintains an important symbiotic relationship with its host by regulating oxalate homeostasis, primarily by preventing enteric absorption. Increased absorption of oxalate can lead to multiple complications associated with hyperoxaluria, especially recurrent calcium oxalate urolithiasis. Detection of O. formigenes in the gastrointestinal tract has attracted attention because the absence of this bacterium appears to be a risk factor for development of hyperoxaluria and/or recurrent calcium oxalate kidney stone disease. In the present study, epidemiologic studies with patients at high risk for calcium oxalate urolithiasis showed a direct correlation between the number of recurrent kidney stone episodes and the lack of O. formigenes colonization. As expected, the lack of O. formigenes revealed a clear association with prophylactic antibiotic therapy. To confirm the importance of O. formigenes in regulating hyperoxaluria, laboratory rats known to be noncolonized were colonized with live bacteria or treated with a preparation of oxalate-degrading enzymes derived from O. formigenes to determine any subsequent increased resistance to high oxalate challenge. Rats receiving either bacteria or enzyme replacement therapy excreted far lower levels of oxalate, did not develop the crystalluria observed with control rats, and resisted the formation of calcium oxalate crystals in their nephrons. These observations, taken together, support the concept that O. formigenes is important in maintaining oxalate homeostasis, that its absence from the gut increases the risk for hyperoxaluria and recurrent kidney stone disease, and that replacement therapy is an efficient procedure to prevent hyperoxaluria and its complications.

Adult↗

PubMed1999

Precipitation of calcium oxalate monohydrate at phospholipid monolayers.

Studies of calcium oxalate monohydrate (COM) precipitation at Langmuir monolayers of the phospholipids dipalmitoylphosphatidylglycerol (DPPG), dipalmitoylphosphatidylcholine (DPPC), and dipalmitoylphosphatidylserine (DPPS) are reported. The precipitation is heterogeneous and selective, with a majority of crystals orienting with the COM (101) face toward the monolayer interface for each phospholipid. The number density of COM crystals depends on the identity of the phospholipid monolayer, decreasing in the order DPPG > DPPS > DPPC. It was also found that COM precipitation increases as the surface pressure of the monolayer is lowered and with the addition of low levels (<0.1%) of cholesterol. The possibility that changes in monolayer fluidity influence COM attachment is discussed.

Calcium Oxalate↗

PubMed1999

Role of urinary bikunin in the inhibition of calcium oxalate crystallization.

Several urinary macromolecules are known to modulate calcium oxalate (CaOx) crystallization. One of these is urinary bikunin, the light chain of inter-alpha-inhibitor. Bikunin has been demonstrated to be an efficient inhibitor of CaOx crystal growth; however, its inhibitory activity against other events in CaOx crystallization has not been fully investigated. To assess the potential of urinary bikunin as an effective inhibitor, its effects on CaOx crystal nucleation and aggregation were evaluated. Nucleation and aggregation of CaOx crystals were studied by measuring turbidity at 620 nm. In the nucleation assay, crystallization was induced by mixing calcium chloride and sodium oxalate, at final concentrations of 3 and 0.5 mM, respectively. Both solutions were buffered with 0.05 M Tris, 0.15 M NaCl, pH 6.5. Nucleation measurements were performed at 37 degrees C, with stirring at 800 rpm. Inhibition of nucleation was estimated by comparing the induction time in the presence of the inhibitor with control values. In the aggregation assay, the optical density of the solution containing CaOx monohydrate crystals was monitored. Inhibition of aggregation was evaluated by comparing the turbidity slope in the presence of the inhibitor with control values. The data showed that urinary bikunin, at concentrations of 2.5 to 20 microg/ml, retarded crystal nucleation by 67 to 58% and inhibited crystal aggregation by 59 to 80%. According to these results, it seems that urinary bikunin is an efficient inhibitor of crystal nucleation and aggregation. Its presence in the kidneys and urine may protect subjects against CaOx crystallization and kidney stone formation.

Calcium Oxalate↗

PubMed1999

Molecular detection of heparan sulfate proteoglycan mRNA in rat kidney during calcium oxalate nephrolithiasis.

The present study used reverse transcription (RT)-PCR to examine heparan sulfate proteoglycan (HSPG) mRNA expression in rat kidneys. Total mRNA in kidney was isolated and converted to cDNA. To confirm the exact expression level of HSPG mRNA, quantitative competitive (QC)-PCR was performed for each sample. PCR products were resolved by electrophoresis on 1.5% agarose gel and visualized with ethidium bromide. Fragment intensity and area were measured using an image analyzer. In QC-PCR, target DNA and competitive DNA were expressed, using gene-specific primer for HSPG mRNA, as 506- and 345-bp bands, respectively. The level of HSPG mRNA expression apparently increased in the nephrolithic rat kidney. Immunohistochemical study revealed that increased production of heparan sulfate was detected in both distal and proximal tubules during nephrolithiasis. These findings suggest that increased expression of HSPG may play a significant role during calcium oxalate stone formation.

Animals↗

PubMed1999

Cells of proximal and distal tubular origin respond differently to challenges of oxalate and calcium oxalate crystals.

LLC-PK1 and Madin-Darby canine kidney (MDCK) cells were used to study the role of free radicals in renal epithelial injury during exposure to oxalate ions (Ox) and calcium oxalate monohydrate (COM) crystals. The cell cultures were exposed for 120 or 240 min to 1.0 mmol Ox or 1.0 mmol Ox plus 500 microg/ml of COM crystals averaging 1.0 microm in size. Exposure of both LLC-PK1 and MDCK cells to Ox alone increased the leakage of lactate dehydrogenase, which was further enhanced when cells were exposed to Ox + COM crystals. The release of lactate dehydrogenase from the LLC-PK1 cell line, however, was significantly higher than that from MDCK cells. LLC-PK1 cells also showed a significant increase in malondialdehyde (MDA) content on Ox challenge. MDA content was even higher when LLC-PK1 cells were challenged with Ox + COM crystals. However, in MDCK cells, the elevated MDA content was similar in both treatment groups, suggesting that these cells may be more resistant to the calcium oxalate crystals. Glutathione peroxidase activity was decreased in both LLC-PK1 and MDCK cells. Challenging cells with Ox + COM resulted in decreased catalase activity in LLC-PK1, but increased catalase activity in MDCK cells. Superoxide dismutase activity and reduced glutathione content were not significantly different in either cell type when challenged with Ox or Ox + COM. Previous in vivo animal studies yielded indirect evidence for the increased lipid peroxidation during hyperoxaluria-induced nephrolithiasis. However, in an animal model, it is difficult to separate the effect of Ox from Ox in combination with COM crystals. This study suggests that the injury to renal tubular epithelial cells is accompanied by lipid peroxidation when exposed to Ox. The injury is augmented when COM crystals are included. LLC-PK1 cells are more susceptible to Ox-associated injury than MDCK cells.

Animals↗

PubMed1999

Crystal-cell interaction and apoptosis in oxalate-associated injury of renal epithelial cells.

Two renal epithelial cell lines, LLC-PK1 and Madin-Darby canine kidney (MDCK), were grown in monolayers and exposed to oxalate (Ox) and/or calcium oxalate (CaOx) crystals to investigate cellular responses to these challenges. In addition, LLC-PK1 cells were exposed to high concentrations of Ox for various time periods to investigate the role of apoptosis in Ox-associated cell injury. Both cell types showed signs of damage when exposed to Ox. However, LLC-PK1 cells appeared more sensitive than MDCK cells. There was a significant increase in release of lactate dehydrogenase into the medium and decrease in trypan blue exclusion by cells in the monolayer. Most noticeable was the detachment of cells from the substrate. Exposure of cells to CaOx crystals resulted in their attachment to cell surfaces followed by internalization. Using flow cytometry for quantification of apoptotic cells, transmission electron microscopy for morphology, and electrophoresis for DNA laddering detection, we observed significant apoptotic changes including condensation and margination of nuclear chromatin, DNA fragmentation, and migration of phosphatidylserine of the plasma membrane from inside to the cell surface. However, these cells also showed some necrotic changes such as loss of plasma membrane integrity and release of lactate dehydrogenase, indicating that the apoptotic process was interrupted.

Animals↗

PubMed1998

Identification of proteins extracted from calcium oxalate and calcium phosphate crystals induced in the urine of healthy and stone forming subjects.

The purpose of our study was to identify the proteins and investigate the differences, if any, between protein components of the matrices of calcium oxalate (CaOx) and calcium phosphate (CaP) crystals induced in vitro in whole human urine of healthy individuals and kidney stone patients. In addition, preliminary studies were performed to understand the effect of centrifugation and filtration of urine on its protein contents. Crystallization in urine was induced by addition of an oxalate or phosphate load. Crystals were collected, washed, and analyzed by scanning electron microscopy, X-ray diffraction, and energy dispersive X-ray microanalysis. Matrix proteins were obtained by demineralization with ethylene diamine tetraacetic acid (EDTA), analyzed by polyacrylamide gel electrophoresis, and identified by western blotting technique. No significant differences were detected between protein components of the matrices of CaOx and CaP crystals and between the crystal matrices obtained from the urine of normal and stone forming subjects. Albumin (AB), inter-alpha-inhibitor (IalphaI) related proteins, alpha-1 microglobulin (alpha-1 m), osteopontin (OPN), prothrombin (PT)-related proteins and Tamm-Horsfall protein (THP) were identified in matrices of both CaOx and CaP crystals induced in urine from both the normal subjects and stone formers. AB, PT-related proteins and OPN were the main constituents. The other proteins were present in smaller but detectable amounts. However, CaP crystal matrix, contained a large amount of THP. In addition CaP crystals contained significantly more proteins than CaOx crystals. Centrifugation and/or filtration of the urine resulted in reduction of many high molecular weight proteins including THP, AB and OPN in the urine.

Albumins↗

PubMed1998

Occurrence and susceptibility to antibiotics of Shigella species in stools of hospitalized children with bloody diarrhea in Pakistan.

The aim of the present investigation was to study the frequency of Shigella spp. in patients with bloody diarrhea in Pakistan and the susceptibility of isolated Shigella to three antibiotics: ampicillin, cotrimoxazole and nalidixic acid. In addition, the frequency of Campylobacter and Salmonella was also determined. Stool samples (n = 152) were collected from 152 diarrheic children less than six years of age passing blood and mucus in their stools who were admitted to Paediatric Department of Mayo Hospital in Lahore, Pakistan from June to September 1990. The samples were cultivated on standard media for Shigella, Campylobacter, and Salmonella. Susceptibility of Shigella isolates was tested by disk diffusion method. The frequency of isolation was 19.1% for Shigella spp., 7.9% for Campylobacter, and 4.6% for Salmonella. Shigella flexneri (7.9%) was the most frequently isolated species, followed by S. dysenteriae (6.6%), S. boydii, (3.3%) and S. sonnei (1.3%). All Shigella isolates were susceptible to nalidixic acid (100%), while only a few were susceptible to cotrimoxazole (7.0%) and ampicillin (3.5%). In Pakistan, self-medication and purchases of drugs without a prescription are commonly practiced. Thus, there is a greater possibility of development of resistant strains due to over use of antibiotics.

Age Factors↗