Iodixanol compared to iohexol for contrast procedures: a case-matched retrospective cohort study.

BACKGROUND: Previous studies that have attempted to evaluate the effectiveness of an iso-osmolar contrast medium (IOCM) iodixanol compared to a low-osmolar contrast medium (LOCM) for contrast procedures show variable results. PURPOSE: To evaluate the nephrotoxicity of the IOCM iodixanol compared to the LOCM iohexol. MATERIAL AND METHODS: We performed a retrospective cohort study from April 2004 to March 2006. All contrast procedures with a pre- and post-exposure creatinine value were evaluated for inclusion. Contrast nephropathy (CN) was defined as post-exposure creatinine elevation of > or = 25% or > 0.5 mg/dl within 7 days of contrast exposure. Cases of iodixanol exposure were matched to control cases of iohexol exposure (1:1) based on age, sex, presence of diabetes, pre-exposure creatinine value, and type of imaging study performed. We matched 397 cases of iodixanol (IOCM) exposure to 397 cases of iohexol (LOCM) exposure. Cases of iodixanol which could not be matched to controls were not included in the analysis. RESULTS: After adjustment for prior creatinine, medications, contrast iodine load, prior exposure to contrast material, heart failure, and hypertension, use of iodixanol did not significantly alter rates of CN compared to iohexol (OR 0.92, 95% CI 0.57-1.46; P = 0.71) or mortality (RR 0.79, 95% CI 0.59-1.06; P = 0.12). CONCLUSION: The use of the IOCM iodixanol was not associated with statistically significant protection against contrast nephropathy or all-cause mortality compared to a matched cohort of patients receiving the LOCM iohexol.

Pheochromocytoma in a patient with end-stage renal disease.

Pheochromocytoma is a rare tumor. To our knowledge only 15 cases have been reported in patients with end-stage renal disease (ESRD). We describe a 46-year-old woman with ESRD and a history of paroxysmal and difficult-to-control hypertension. During anesthesia for a surgical procedure, the patient experienced blood pressure lability with systolic blood pressures ranging from 76 to 360 mm Hg. Serum catecholamine concentrations were 2,698 pg/ mL (reference value, <750 pg/mL) for norepinephrine, 33 pg/mL (<110 pg/mL) for epinephrine, and 55 pg/mL (<30 pg/mL) for dopamine. The concentrations of plasma metanephrines were 6.84 nmol/L (<0.50 nmol/L) for metanephrine and 14.64 nmol/L (<0.90 nmol/L) for normetanephrine. Abdominal computed tomography showed a right-sided, 4-cm mass posterior to the infrahepatic inferior vena cava. Following blood pressure control with alpha- and beta-adrenergic blockade, the mass was removed. Pathologic examination demonstrated the mass was a pheochromocytoma. The maximum postoperative systolic blood pressure was 160 mm Hg. Postoperative plasma normetanephrine concentration was 2.80 nmol/L, and metanephrine was obscured by interfering substances. This case report and literature review emphasizes the difficulty in diagnosing pheochromocytomas in patients with ESRD despite the myriad of available diagnostic tests.

Neck needle foreign bodies: an added risk for autopsy pathologists.

The risk to pathologists of contracting diseases due to cuts or needles punctures while performing autopsies is well known. An additional risk is an accidental needle puncture due to retained needle fragments within the subcutaneous tissues or internal organs of intravenous drug addicts. We report 4 cases of drug addicted patients infected with human immunodeficiency virus who came to autopsy and had retained needle fragments within their cervical-clavicular soft tissues. The presence of retained needle fragments increases the risk to the autopsy pathologist of accidental needle puncture and exposure to disease. Because of this phenomenon, the pathologist should take precautions in addition to those currently prescribed when performing autopsies on possible drug abusers.

beta-Carotene stability and uptake by prostate cancer cells are dependent on delivery vehicle.

Cell culture systems provide an opportunity to evaluate the effects of carotenoids on molecular and cellular processes involved in proliferation and differentiation of prostate cancer cells. The stability and cellular uptake of beta-carotene (BC) by prostate cancer cells were investigated in vitro by use of various delivery methods and three human prostate adenocarcinoma cell lines: PC-3, DU 145, and LNCaP. Recovery of BC from the media (prepared from water-dispersible BC beadlets) significantly (p < 0.05) decreased after 12 hours in culture and continued to significantly decrease (p < 0.05) after 24, 48, 72, and 96 hours, an observation primarily attributed to BC degradation rather than isomerization, metabolism, or cellular uptake. The uptake of BC by prostate cancer cells was compared when delivered by tetrahydrofuran, BC-enriched bovine serum, water-dispersible BC beadlets, and artificial liposomes. Recovery of BC after three days in culture from enriched bovine serum medium was significantly (p < 0.05) greater than recovery from medium prepared by beadlets, tetrahydrofuran, or artificial liposomes. We conclude that BC is relatively unstable in vitro and that degradation products may contribute to biological responses. Furthermore, our studies indicate that enriched bovine serum provides a stable and physiological approach to carotenoid treatment of cells in culture.

Beta-carotene modulates human prostate cancer cell growth and may undergo intracellular metabolism to retinol.

Epidemiologic and animal studies provide support for a relationship between high intakes of carotenoids from fruits and vegetables with reduced risk of several malignancies including prostate cancer. The highly controlled environments of in vitro systems provide an opportunity to investigate the cellular and molecular effects of carotenoids. The effects of beta-carotene (BC) on in vitro growth rates, p21(WAF1) and p53 gene expression, as well as the conversion of BC to retinol were investigated in three human prostate adenocarcinoma cell lines: PC-3, DU 145 and LNCaP. In these experiments, media concentrations of 30 micromol BC/L for 72 h significantly (P < 0.05) slowed in vitro growth rates in all three cell lines, independently of p53 or p21(WAF1) status or expression. (14)C-labeled retinol was detected in prostate tumor cells incubated with (14)C-labeled BC, suggesting metabolic conversion of BC to retinol. Conversely, no (14)C-labeled retinol was detected in media incubated without prostate cancer cells. These studies support a hypothesis that in vitro biological effects of BC on prostate cells may result in part from the conversion of BC to retinol or other metabolites. The possibility that prostate cancer cells in vivo locally metabolize provitamin A carotenoids to retinol and other related metabolites may have implications for our understanding of prostate cancer etiology and the design of future prevention studies.

Heroin body packing: three fatal cases of intestinal perforation.

Death from heroin body packing has been well described in the forensic literature. Most fatalities are due to drug leakage and consequent acute heroin toxicity. Recently, drug traffickers have become more sophisticated in their packaging, and the risk of rupture of drug packets is more remote. Though intestinal obstruction is a recognized risk of body packing, rarely has this resulted in death. We describe four cases of heroin body packing presenting to the Regional Medical Examiner Office in New Jersey. Death in three of these cases was due to intestinal obstruction, with resultant intestinal rupture and peritonitis. Toxicologic evaluation in these three cases was negative for opiates or other drugs of abuse. In one case, death was due to acute heroin toxicity, validated by toxicologic analysis. We briefly discuss the differing drug packaging found in these four cases and the ramifications of packaging as it relates to intestinal obstruction.

Review of animal models in carotenoid research.

Foods containing provitamin A carotenoids are the primary source of vitamin A in many countries, despite the poor bioavailability of carotenoids. In addition, epidemiologic studies suggest that dietary intake of carotenoids influences the risk for certain types of cancer, cardiovascular disease and other chronic diseases. Although it would be ideal to use humans directly to answer critical questions regarding carotenoid absorption, metabolism and effects on disease progression, appropriate animal models offer many advantages. This paper will review recent progress in the development of animal models with which to study this class of nutrients. Each potential model has strengths and weaknesses. Like humans, gerbils, ferrets and preruminant calves all absorb beta-carotene (betaC) intact, but only gerbils and calves convert betaC to vitamin A with efficiency similar to that of humans. Mice and rats efficiently convert betaC to vitamin A but absorb carotenoids intact only when they are provided in the diet at supraphysiologic levels. Mice, rats and ferrets can be used to study cancer, whereas primates and gerbils are probably more appropriate for studies on biomarkers of heart disease. No one animal model completely mimics human absorption and metabolism of carotenoids; thus the best model must be chosen with consideration of the specific application being studied, characteristics of the model, and the available funding and facilities.

Isolation and characterization of a thymidylate synthase-deficient human colon tumor cell line.

Following mutagenesis of the human colorectal tumor cell line HCT C with ethyl methanesulfonate, clonal sublines were isolated that survived on medium toxic to cells expressing thymidylate synthase (TS). The subline exhibiting the lowest TS activity, designated as C18, was characterized. Extracts from C18 cells were mixed with extracts from parental C cells to determine whether the TS-deficient phenotype is trans-acting. No effect was observed on the activity of TS in parental extracts. The levels of functional TS in C18 cells were analyzed by the binding of the mechanism-based inhibitor 5-fluoro-2'-deoxyuridylate (FdUMP) under conditions that allowed for the detection of 10 fmol of TS. Only a low level of FdUMP-TS complexes was detected in C18 extracts. The level of TS expression in C18 cells was similar to that in parental C cells, as indicated by immunoblot and RNA analyses. DNA sequence analysis of TS cDNA from C18 cells revealed the existence of a point mutation (C-->T) at nucleotide 647 that predicts the replacement of Ser216 by a leucine residue. That the C18 cell line was homozygous for this mutation was indicated by restriction fragment-length polymorphism analysis and by primer extension analysis. To provide additional evidence that substitution of Ser216 by a leucine residue created a defective protein, a TS-deficient bacterial strain was transformed with an expression vector containing the mutated human TS cDNA. The transformed strain exhibited thymidine auxotrophy, indicating that the mutant TS (Leu216) is nonfunctional.

Improved biochemical variables, nutrient intake, and hormonal factors in slow nocturnal hemodialysis: a pilot study.

OBJECTIVE: To determine whether slow nocturnal hemodialysis (SNHD) can be safely performed in patients with end-stage renal disease to improve the biochemical and clinical outcome. MATERIAL AND METHODS: We conducted an 8-week pilot study in nondiabetic adult patients, who underwent dialysis 6 nights per week for 8 hours each night. A dialysate flow rate of 300 mL/min and a blood flow rate of 250 mL/min, through an internal jugular dual-lumen venous catheter, were used. The equipment used was a COBE Centry System 3 dialysis machine and Fresenius F-80 (1.8 m2) or Baxter CT 190 (1.9 m2) dialyzers. Five patients were enrolled in the study. RESULTS: Two patients did not complete the study because of catheter-related infections--one at day 7 and one after 4 weeks of SNHD. All patients had improved blood pressure control, and no intradialytic adverse events occurred. Dietary intake improved, urea and creatinine levels significantly decreased, and weekly delivery of dialysate increased on SNHD. Potassium, chloride, beta 2-microglobulin, phosphorus, calcium, and high-density lipoprotein cholesterol all improved on SNHD. Serum testosterone increased in the three men on SNHD, but parathyroid hormone, luteinizing hormone, and follicle-stimulating hormone remained unchanged. Erythropoietin levels increased on SNHD, despite no change in exogenous erythropoietin doses in three patients and discontinuation of administration of erythropoietin in one. The following biochemical factors did not change significantly: serum sodium, bicarbonate, vitamin B12, folate, alkaline phosphatase, total cholesterol, triglycerides, and albumin. CONCLUSION: Higher doses of hemodialysis benefit nutrition, improve biochemical variables, and may improve many hormonal systems.

A hydroxyl group at residue 216 is essential for catalysis by human thymidylate synthase.

Structural analyses of bacterial thymidylate synthases (TSs) implicate a serine residue corresponding to Ser216 in human TS in hydrogen bond networks that are involved in binding of the nucleotide substrate, 2'-deoxyuridylate (dUMP), and that stabilize a beta-bulge in the protein. Utilizing site-directed mutagenesis, 12 mutant proteins were created with substitutions at residue 216. DNA complementation studies utilizing a TS-negative bacterial strain revealed that only one mutant, Thr216 TS, supports the growth of the bacteria in the absence of thymidine. Kinetic characterization of the mutant proteins revealed that all TSs except Thr216 TS exhibited kcat/Kms for dUMP that are 10(3)-10(4) times lower, relative to that of wild-type TS. In addition, Thr216 TS was the only mutant to bind the mechanism-based inhibitor, 5-fluoro-2'-deoxyuridylate (FdUMP), into a ternary complex. Ligand binding studies revealed that Kds for dUMP binding to two defective mutants, Ala216 and Leu216 TSs, are 12-16-fold higher than that of wild-type TS. The data are consistent with the hypothesis that serine at this relative position is involved in dUMP binding; however, the data indicate that Ser216 has effects on catalysis, in addition to effects on dUMP binding. Catalysis is initiated by nucleophilic attack of the active site cysteine of TS on dUMP. The reaction rates of cysteine residues with the sulfhydryl reagent 5,5'-dithiobis(2-nitrobenzoic acid) were slower for Ala216 TS than for wild-type TS.

YopD of Yersinia pestis plays a role in negative regulation of the low-calcium response in addition to its role in translocation of Yops.

Yersinia pestis produces a set of virulence proteins (Yops and LcrV) that are expressed at high levels and secreted by a type III secretion system (Ysc) upon bacterium-host cell contact, and four of the Yops are vectorially translocated into eukaryotic cells. YopD, YopB, and YopK are required for the translocation process. In vitro, induction and secretion occur at 37 degrees C in the absence of calcium. LcrH (also called SycD), a protein required for the stability and secretion of YopD, had initially been identified as a negative regulator of Yop expression. In this study, we constructed a yopD mutation in both wild-type and secretion-defective (ysc) Y. pestis to determine if the lcrH phenotype could be attributed to the decreased stability of YopD. These mutants were constitutively induced for expression of Yops and LcrV, despite the presence of the secreted negative regulator LcrQ, demonstrating that YopD is involved in negative regulation, regardless of a functioning Ysc system. Normally, secretion of Yops and LcrV is blocked in the presence of calcium. The single yopD mutant was not completely effective in blocking secretion: LcrV was secreted equally well in the presence and absence of calcium, while there was partial secretion of Yops in the presence of calcium. YopD is probably not rate limiting for negative regulation, as increasing levels of YopD did not result in decreased Yop expression. Overexpression of LcrQ in the yopD mutant had no significant effect on Yop expression, whereas increased levels of LcrQ in the parent resulted in decreased levels of Yops. These results indicate that LcrQ requires YopD to function as a negative regulator.

Failure to detect binding of LcrH to the V antigen of Yersinia pestis.

V antigen of Yersinia pestis has been reported to bind the chaperone LcrH. We were unable to demonstrate this interaction. Despite methodological differences between our study and an earlier study, we believe that the previous findings were artifactual. One likely confounding element was the tendency of LcrH to adhere on its own to metal chelation chromatographic resin.

Improved preservation of residual renal function in chronic hemodialysis patients using polysulfone dialyzers.

Our objective was to determine whether patients with chronic renal failure requiring maintenance hemodialysis retain intrinsic renal function longer when using reprocessed polysulfone (PS) membrane hemodialyzers or single-use cellulose acetate (CA) membrane hemodialyzers. Fifty consecutive patients with residual renal function (urea clearance > 2.0 mL/min) using PS dialyzers were compared with a retrospective, disease- and time-matched population of patients using CA dialyzers. Endogenous urea clearance was measured every 3 months in all patients with remaining residual function. Other data collected included age, sex, cause of chronic renal failure, use of angiotensin-converting enzyme inhibitors or calcium channel blockers, and hemodynamic stability during hemodialysis. All patients were observed for at least 6 months while using a single type of dialyzer. Study end points included loss of residual renal function (urea clearance < 1.0 mL/min), death, transplant, transfer to peritoneal dialysis, or change of dialyzer. The PS and CA groups of patients were well matched for sex, age, initial renal clearance, predialysis blood pressure, and hemodynamic stability during hemodialysis. The PS patients had a higher delivered Kt/V (1.34 +/- 0.30 [mean +/- SD]) than the CA patients (1.06 +/- 0.20). The PS group had a higher average urea clearance than the CA group after 4 to 9 months of dialysis (2.8 +/- 2.6 mL/min v 1.7 +/- 1.6 mL/min, respectively), after 10 to 15 months of chronic dialysis (2.0 +/- 2.4 mL/min v 1.1 +/- 1.5 mL/min, respectively), and after 16 to 21 months of dialysis (1.3 +/- 1.9 mL/min v 0.5 +/- 1.1 mL/min, respectively; all P < 0.03, t-test). After 22 to 24 months of dialysis, the difference between the two groups was not significant. When comparing patients with identical causes of chronic renal failure, there were no differences between the PS and CA groups for those with diabetes mellitus, tubulointerstitial disease, or polycystic disease. Patients with parenchymal renal disease (glomerulonephritis or nephrosclerosis) had markedly better retention of intrinsic renal function with PS than with CA dialyzers (all P < 0.01). Kaplan-Meier analysis for retention of intrinsic renal function showed that PS patients with parenchymal renal disease had a mean of 23 months before loss of intrinsic renal function, whereas for CA patients the mean was 11 months before loss of intrinsic renal function (P = 0.0005). Cellulose acetate patients lost renal function at an average rate of 0.27 +/- 0.22 mL/min/mo, whereas for PS patients the rate was 0.14 +/- 0.56 mL/min/mo (P = 0.06, rank sum). CA patients with parenchymal renal disease lost renal function at a rate of 0.29 +/- 0.22 mL/min/mo, whereas for PS patients the rate was 0.0 +/- 0.8 mL/min/mo (P = 0.004, rank sum). Age, sex, and the use of either angiotensin-converting enzyme inhibitors or calcium channel blockers did not have an effect on the loss of intrinsic renal function. Patients with nondiabetic parenchymal renal disease receiving chronic hemodialysis with hydrogen peroxide/peroxyacetic acid-reprocessed PS dialyzers and a higher Kt/V lose residual renal function at a slower rate than disease-matched patients using single-use CA dialyzers. Our findings provide further evidence that the choice of dialyzer membrane may have an effect on intrinsic renal function.

Yersinia pestis LcrV forms a stable complex with LcrG and may have a secretion-related regulatory role in the low-Ca2+ response.

Yersinia pestis contains a virulence plasmid, pCD1, that encodes many virulence-associated traits, such as the Yops (Yersinia outer proteins) and the bifunctional LcrV, which has both regulatory and antihost functions. In addition to LcrV and the Yops, pCD1 encodes a type III secretion system that is responsible for Yop and LcrV secretion. The Yop-LcrV secretion mechanism is believed to regulate transcription of lcrV and yop operons indirectly by controlling the intracellular concentration of a secreted repressor. The activity of the secretion mechanism and consequently the expression of LcrV and Yops are negatively regulated in response to environmental conditions such as Ca2+ concentration by LcrE and, additionally, by LcrG, both of which have been proposed to block the secretion mechanism. This block is removed by the absence of Ca2+ or by contact with eukaryotic cells, and some Yops are then translocated into the cells. Regulation of LcrV and Yop expression also is positively affected by LcrV. Previously, LcrG was shown to be secreted from bacterial cells when the growth medium lacks added Ca2+, although most of the LcrG remains cell associated. In the present study, we showed that the cell-associated LcrG is cytoplasmically localized. We demonstrated that LcrG interacts with LcrV to form a heterodimeric complex by using chemical cross-linking and copurification of LcrG and LcrV. Additionally, we found that small amounts of LcrV and YopE can be detected in periplasmic fractions isolated by cold osmotic shock and spheroplast formation, indicating that their secretion pathway is accessible to the periplasm or to these procedures for obtaining periplasmic fractions. We propose that the cytoplasmically localized LcrG blocks the Yop secretion apparatus from the cytoplasmic side and that LcrV is required to remove the LcrG secretion block to yield full induction of Yop and LcrV secretion and expression.

cis-trans lycopene isomers, carotenoids, and retinol in the human prostate.

An evaluation of the Health Professionals Follow-Up Study has detected a lower prostate cancer risk associated with the greater consumption of tomatoes and related food products. Tomatoes are the primary dietary source of lycopene, a non-provitamin A carotenoid with potent antioxidant activity. Our goal was to define the concentrations of lycopene, other carotenoids, and retinol in paired benign and malignant prostate tissue from 25 men, ages 53 to 74, undergoing prostatectomy for localized prostate cancer. The concentrations of specific carotenoids in the benign and malignant prostate tissue from the same subject are highly correlated. Lycopene and all-trans beta-carotene are the predominant carotenoids observed, with means +/- SE of 0.80 +/- 0.08 nmol/g and 0.54 +/- 0.09, respectively. Lycopene concentrations range from 0 to 2.58 nmol/g, and all-trans beta-carotene concentrations range from 0.09 to 1.70 nmol/g. The 9-cis beta-carotene isomer, alpha-carotene, lutein, alpha-cryptoxanthin, zeaxanthin, and beta-cryptoxanthin are consistently detectable in prostate tissue. No significant correlations between the concentration of lycopene and the concentrations of any other carotenoid are observed. In contrast, strong correlations between prostate beta-carotene and alpha-carotene are noted (correlation coefficient, 0.88; P < 0.0001), as are correlations between several other carotenoid pairs, which reflects their similar dietary origins. Mean vitamin A concentration in the prostate is 1.52 nmol/g, with a range of 0.71 to 3.30 nmol/g. We further evaluated tomato-based food products, serum, and prostate tissue for the presence of geometric lycopene isomers using high-performance liquid chromatography with a polymeric C30 reversed phase column. All-trans lycopene accounts for 79 to 91% and cis lycopene isomers for 9 to 21% of total lycopene in tomatoes, tomato paste, and tomato soup. Lycopene concentrations in the serum of men range between 0.60 and 1.9 nmol/ml, with 27 to 42% all-trans lycopene and 58 to 73% cis-isomers distributed among 12 to 13 peaks, depending upon their chromatographic resolution. In striking contrast with foods, all-trans lycopene accounts for only 12 to 21% and cis isomers for 79 to 88% of total lycopene in benign or malignant prostate tissues. cis Isomers of lycopene within the prostate are distributed among 14 to 18 peaks. We conclude that a diverse array of carotenoids are found in the human prostate with significant intra-individual variation. The presence of lycopene in the prostate at concentrations that are biologically active in laboratory studies supports the hypothesis that lycopene may have direct effects within the prostate and contribute to the reduced prostate cancer risk associated with the reduced prostate cancer risk associated with the consumption of tomato-based foods. The future identification and characterization of geometric lycopene isomers may lead to the development of novel agents for chemoprevention studies.

Remote in situ analytical spectroscopy and its applications in the nuclear industry.

An experimental system based on Laser Induced Breakdown Spectroscopy (LIBS) has been used to analyze various ferrous samples. A fibre optic system has been used to transmit the incident laser pulse which produces the plasma plume at the surface of the analyte and to transmit back to a spectrometer the optical radiation emitted by the plasma. The measuring system may therefore be placed remote from the analyte which may be situated in a hostile environment such as an operating nuclear reactor. Results show that the system is capable of detecting chromium, nickel, manganese, molybdenum, silicon and vanadium at concentrations smaller than 5x10(-4) g/g

Characterization of the flagellar hook length control protein fliK of Salmonella typhimurium and Escherichia coli.

During flagellar morphogenesis in Salmonella typhimurium and Escherichia coli, the fliK gene product is responsible for hook length control. A previous study (M. Homma, T. Iino, and R. M. Macnab, J. Bacteriol. 170:2221-2228, 1988) had suggested that the fliK gene may generate two products; we have confirmed that both proteins are products of the fliK gene and have eliminated several possible explanations for the two forms. We have determined the DNA sequence of the fliK gene in both bacterial species. The deduced amino acid sequences of the wild-type FliK proteins of S. typhimurium and E. coli correspond to molecular masses of 41,748 and 39,246 Da, respectively, and are fairly hydrophilic. Alignment of the sequences gives an identity level of 50%, which is low for homologous flagellar proteins from S. typhimurium and E. coli; the C-terminal sequence is the most highly conserved part (71% identity in the last 154 amino acids). The central and C-terminal regions are rich in proline and glutamine residues, respectively. Linker insertion mutagenesis of the conserved C-terminal region completely abolished motility, whereas disruption of the less conserved N-terminal and central regions had little or no effect. We suggest that the N-terminal (or N-terminal and central) and C-terminal regions may constitute domains. For several reasons, we consider it unlikely that FliK is functioning as a molecular ruler for determining hook length and conclude that it is probably employing a novel mechanism.