Adjuvant and neoadjuvant treatment for rectal cancer, colon cancer, and non-small-cell lung cancer in older patients

Evidence-based treatment guidelines exist to improve quality of care for patients and are based on randomized trials that show evidence of benefit.[...]

Geographic disparities in surgery for breast and rectal cancer in Canada

Equitable access to appropriate cancer treatment is fundamental for achieving universal, high-quality cancer care [...]

Examining Cancer-Risk Profiles for the Largest Metropolitan Areas across Canada

Because health behaviours can be influenced at many different levels, there is value in examining differences in risk factors and health behaviours between the largest cities in Canada. [...]

Provincial rates and time trends in pancreatic cancer outcomes

Pancreatic cancer, often called the “silent killer,” is the twelfth most common cancer in Canada, with an estimated 4600 new cases in 2012. [...]

Measuring concordance with guidelines for the diagnosis and treatment of colon cancer

Colorectal cancer is the second leading cause of cancer death and the third most commonly diagnosed cancer in Canada, with an estimated 9200 deaths and 23,300 new cases in 2012. [...]

New chart review data validate administrative data-based indicator for guideline-recommended treatment of locally advanced non-small-cell lung cancer and shed light on reasons for non-referral and non-treatment

The 2012 Cancer System Performance Report is the 4th annual report on the Canadian cancer control system produced by the System Performance initiative at the Canadian Partnership Against Cancer, in collaboration with its provincial and national partners. [...]

Indicator measures er/pr and her2 testing among women with invasive breast cancer

As part of its System Performance initiative, the Canadian Partnership Against Cancer released Breast Cancer Control in Canada: A System Performance Special Focus Report in September 2012, presenting a broad range of system performance indicators that measure breast cancer control across the continuum. [...]

Corrigendum: A First Look at Participation Rates in Cervical Cancer Screening Programs in Canada

K. Decker and and the Pan-Canadian Cervical Cancer Screening Initiative: Monitoring Program Performance Working Group is to be added to the author list. [...]

A retrospective chart review validates indicator results and provides insight into reasons for non-concordance with evidence-based guidelines

As part of the system performance initiative of the Canadian Partnership Against Cancer, indicators measuring treatment practice patterns across the country relative to evidence-based guidelines were first published in 2010 and are updated annually. Among the treatment indicators examined is the percentage of resected stage ii and iii rectal cancer patients receiving neoadjuvant (preoperative) radiation therapy (RT), the treatment approach recommended for locally advanced rectal cancer

A first look at participation rates in cervical cancer screening programs in Canada

In 2011, the Pan-Canadian Cervical Cancer Screening Initiative (PCCSI), supported by the Canadian Partnership Against Cancer, released Cervical Cancer Screening in Canada: Monitoring Program Performance 2006–2008 and for the first time presented information on 12 national quality indicators relating to provincial and territorial cervical cancer screening programs. [...]

Polychlorinated dibenzodioxins, dibenzofurans, and biphenyls in fresh water fish from Campania Region, southern Italy

Twenty-eight fish muscle specimens from the main water bodies of the Campania Region were analyzed in our laboratory. On average, results showed a low contamination by PCDDs+PCDFs and a relatively more important presence of DL-PCBs. All specimens were compliant with EU regulatory maximum levels. Cumulative PCDD+PCDF+DL-PCB concentrations (TEQ(TOT)) were comprised in the range 0.223-11.4 pgWHO(97)-TEQ g(-1) fresh weight (fw). DL-PCB contribution to TEQ(TOT) was on average greater than 86% (range, 50.2-97.1%). The cumulative concentrations of 30 non-dioxin-like PCB congeners (Σ(30)(NDL-PCBs)) and of the six indicators (Σ(6)(NDL-PCBs)) were respectively in the ranges 3.30-515 and 1.30-195 ng g(-1) fw. The hybrid clustering approach adopted to analyze the sample-specific congener profiles indentified the main analytical patterns present in the database and, in particular, two main diverse exposure macro-areas that seem to exist north and south of the city of Naples. The distribution of PCDD and PCDF congeners among different species showed significant variations from chub (Leuciscus cephalus), characterized by a higher proportion of low-chlorinated congeners (e.g. 2,3,7,8-T(4)CDD), to eel (Anguilla anguilla), whose contamination consisted mainly of highly chlorinated congeners (e.g. O(8)CDD). To have a more complete perspective in relation to the contaminants present in the environment, the study suggestion is to use benthic as well as pelagic species to obtain an integrated characterization of fish tissue contamination.

Recently published indicators allow for comparison of radiation treatment rates relative to evidence-based guidelines for rectal cancer

The system performance initiative of the Canadian Partnership Against Cancer is the first pan-Canadian report to offer indicators for measuring treatment practice patterns by province and for comparing practice with current guidelines [...]

Abstract 16: ApoA5 Reduces Atherosclerosis in LDL Receptor-Deficient Mice

Apolipoprotein A5 (ApoA5) is a lipid-binding protein that is associated mainly with high-density lipoprotein (HDL) and to a lesser extent with very low-density lipoprotein (VLDL). ApoA5 gene variants are linked to altered lipid metabolism and increased risk of cardiovascular disease in humans. To investigate the role of ApoA5 in lipid metabolism, we placed transgenic mice expressing human ApoA5 and age/sex-matched control littermates on high fat diet for 20 weeks. We show that transgenic production of human ApoA5 resulted in significant improvement in hepatic and plasma lipid metabolism, protecting against the development of dyslipidemia and fatty liver disease in high fat-fed mice. To address the underlying mechanism, we determined hepatic triglyceride production vs. systemic triglyceride clearance. ApoA5 transgenic mice, as opposed to control littermates, exhibited significantly reduced hepatic output and enhanced clearance of triglyceride-rich particles. Furthermore, we show that purified ApoA5 proteins were capable of stimulating lipoprotein lipase (LPL) activity, contributing to accelerated VLDL-TG hydrolysis in a cell-free system. To determine the potential beneficial effect of ApoA5 on atherogenesis, we crossed the human ApoA5 transgene into LDL receptor knockout (LDLR-/-) mice. We demonstrate that transgenic ApoA5 production resulted in significant reduction in plasma lipid levels in LDLR -/- mice on high fat and high cholesterol diet. This effect translated into a significant reduction in atherosclerotic lesion in the aortic root of LDLR -/- mice.

From our studies we conclude: 1) ApoA5 acts to inhibit hepatic lipogenesis and limit hepatic VLDL-TG output, 2) ApoA5 augments LPL activity and enhances the systemic clearance of TG-rich particles, and 3) ApoA5 possesses anti-atherogenic property, protecting against the development of atherosclerosis in LDLR -/- mice.

Judicial sentencing in Canadian intimate partner sexual assault cases

This article examines judicial descriptions of and responses to intimate partner sexual assaults in the Canadian context. Drawing on data from sexual assault sentencing judgments, we investigated 186 cases across four categories of perpetrator-victim relationship. Offence and case-related characteristics, as well as sentencing outcomes were analyzed. The data indicated notable similarities between intimate partner and stranger sexual assaults in terms of the occurrence of penetration, force, and injury. At the same time, our analyses revealed that strangers received longer sentences than intimate perpetrators. Some significant differences were also found between intimate partner and authority figure relationship groups across the variables examined.

Psychological and physical sequelae of intimate partner violence among women with limitations in their activities of daily living

OBJECTIVE

To compare the psychological and physical sequelae of physical/sexual intimate partner violence in women with and without activity limitations.

METHODS

We analyzed data from the Canadian 1999 General Social Survey. We included women reporting intimate partner violence in the previous 5 years (n = 897).

RESULTS

As a result of the violence, women with activity limitations were significantly more likely to feel ashamed/guilty (21.7 vs. 14.5%), depression/anxiety (31.5 vs. 19.8%), fearful (43.0 vs. 33.0%), lowered self-esteem (35.2 vs. 21.1%), increased caution/awareness (20.3 vs. 10.9%), and problems relating to men (16.4 vs. 5.4%). Significantly more women with activity limitations reported physical injury from violence (57.0 vs. 36.6%) and having to take time off from everyday activities (42.1 vs. 30.3%). Women with activity limitations had higher medication use for sleeping problems (OR = 3.17, 95% CI = 1.36, 5.73), anxiety (OR = 3.29, 95% CI = 1.75, 6.19) and depression (OR = 2.63, 95% CI = 1.41, 4.90).

CONCLUSION

Results suggest an additive effect between intimate partner violence and activity limitations that adds disproportionately to the burden of health for women with activity limitations.

A large high-density lipoprotein enriched in apolipoprotein C-I: a novel biochemical marker in infants of lower birth weight and younger gestational age

CONTEXT

Low birth weight is associated with increased cardiovascular disease in adulthood, and differences in the molecular weight, composition, and quantity of lipoprotein subclasses are associated with coronary artery disease.

OBJECTIVE

To determine if there are novel patterns of lipoprotein heterogeneity in low-birth-weight infants.

DESIGN, SETTING, AND PARTICIPANTS

Prospective study at a US medical center of a representative sample of infants (n = 163; 70 white and 93 black) born at 28 or more weeks of gestational age between January 3, 2000, and September 27, 2000. This sample constituted 20% of all infants born during the study period at this site.

MAIN OUTCOME MEASURES

Plasma levels and particle sizes of lipoprotein subclasses and plasma concentrations of lipids, lipoproteins (high-density lipoprotein [HDL] and low-density lipoprotein [LDL]), and apolipoproteins.

RESULTS

An elevated lipoprotein peak of a particle with density between 1.062 and 1.072 g/mL was identified using physical-chemical methods. This subclass of large HDL was enriched in apolipoprotein C-I (apo C-I). Based on the amount of the apo C-I-enriched HDL peak, 156 infants were assigned to 1 of 4 groups: 0 (none detected), 17%; 1 (possibly present), 41%; 2 (probably present), 22%; 3 (elevated), 19%. Infants in group 3, compared with those in the other 3 groups, had significantly (P<.001) lower mean birth weight (2683.7 vs 3307.1 g) and younger mean gestational age (36.2 vs 39.3 wk). After correction for age, infants in group 3 had significantly higher levels of total and large HDL cholesterol and of total and large LDL cholesterol and LDL particle number. However, infants in group 3 had lower levels of small HDL, very low-density lipoproteins, and triglycerides than infants in the other 3 groups. This lipoprotein profile differed from that in infants born small for gestational age, who had significantly higher triglyceride (P<.001) and apo B (P = .04) levels, but lower levels of total and large HDL cholesterol (P<.001) and apo A-I (P<.001).

CONCLUSIONS

Because apo C-I-enriched HDL, and purified apo C-I alone, promotes apoptosis in vitro, increased amounts of this particle may have physiological significance and identify a novel group of low-birth-weight infants apparently distinct from traditionally classified small-for-gestational-age infants.

Differential Additive Effects of Endothelial Lipase and Scavenger Receptor-Class B Type I on High-Density Lipoprotein Metabolism in Knockout Mouse Models

OBJECTIVE

Endothelial lipase (EL) is a vascular phospholipase that hydrolyzes high-density lipoprotein (HDL) as its preferred substrate. Scavenger receptor-class B type I (SR-BI) is an HDL receptor that mediates the selective uptake of cholesteryl ester. This study investigates the role of EL and SR-BI in the regulation of HDL metabolism in gene knockout mouse models.

METHODS AND RESULTS

We cross-bred EL-/- and SR-BI-/- mice and generated single- and double-null mice. We used biochemical, molecular biology, and nuclear magnetic resonance methods to analyze HDL concentration, composition, and structure. We found that EL and SR-BI display additive effects on HDL with evident gene dosage effects, but their mechanisms to regulate HDL concentration and composition are different. Whereas the elevated HDL cholesterol level in EL-/- mice is associated with increased phospholipid content in HDL particles, SR-BI-/- mice display markedly enlarged HDL particles shifted to larger subclasses with a phospholipid content similar to that of wild-type mice. Furthermore, absence of EL is associated with a 40% to 50% inhibition and absence of SR-BI, a approximately 90% inhibition of endogenous lecithin cholesterol:acyltransferase rate.

CONCLUSIONS

EL and SR-BI are major genetic determinants of HDL metabolism in vivo, each exercising independent and additive effects on HDL structure and function.

Targeted replacement of mouse apolipoprotein A-I with human ApoA-I or the mutant ApoA-IMilano. Evidence of APOA-IM impaired hepatic secretion

Despite a pro-atherogenic profile, individuals carrying the molecular variant (R173C) of apolipoprotein (apo)A-I, named apoA-I(Milano) (apoA-I(M)), appear to be at reduced risk for cardiovascular disease. To develop an in vivo system to explore, in a controlled manner, the effects of apoA-I(M) on lipid metabolism, we have used the gene targeting technology, or "gene knock-in" (gene k-in), to replace the murine apoA-I gene with either human apoA-I or apoA-I(M) genes in embryonic stem cells. As in human carriers, mice expressing apoA-I(M) (A-I(M) k-in) are characterized by low concentrations of the human apolipoprotein and reduced high density lipoprotein cholesterol levels, compared with A-I k-in animals. The aim of the present study was to investigate the basic mechanisms of hypoalphalipoproteinemia associated with the apoA-I(M) mutation. ApoA-I and apoA-I(M) mRNA expression, as assessed by Northern blot analysis and quantitative real time reverse transcription-PCR, did not exhibit significant differences in either liver or intestine. Moreover, human apolipoprotein synthesis rates were similar in the k-in lines. When the secretion rate of the human apolipoproteins was assessed in cultured hepatocytes from the mouse lines, secretion from apoA-I(M)-expressing cells was markedly reduced (42% for A-I(M) k-in and 36% for A-I/A-I(M) k-in mice) as compared with that of A-I k-in hepatocytes. These results provide the first evidence that the hypoalphalipoproteinemia in apoA-I(M) human carriers may be partially explained by impaired apoA-I(M) secretion.

[Review of significant studies on monomer vinyl chloride produced in municipal waste landfill plants]

It is known that presently in Italy about 78% of generated urban waste solids get deposited in waste dumpsites. As of today, there is little known knowledge regarding the quality of the ambient surrounding dumpsites. Therefore it has become extremely important to understand the "risk factors" associated with a dumpsite. Through recent studies carried out mostly in the USA, there is evidence of widespread presence of vinyl chloride monomer (VCM) in the environment in proximity of industrial as well as urban dumpsites. The following is a summary of the most significant study reports with respect to the above. From an estimate based on study results, it is estimated that waste dumpsites in the USA emit altogether between 60 and 33,000 tons/year of vinyl chloride monomer into the atmosphere and ground water. Consequently these studies have shown the necessity to include vinyl chloride monomer amongst the monitoring parameters at waste dumpsites both during the operational phase, as well as during the post mortem phase.

Apolipoprotein B RNA editing enzyme-deficient mice are viable despite alterations in lipoprotein metabolism

RNA editing in the nucleus of higher eukaryotes results in subtle changes to the RNA sequence, with the ability to effect dramatic changes in biological function. The first example to be described and among the best characterized, is the cytidine-to-uridine editing of apolipoprotein B (apo-B) RNA. The editing of apo-B RNA is mediated by a novel cytidine deaminase, apobec-1, which has acquired the ability to bind RNA. The stop translation codon generated by the editing of apo-B RNA truncates the full-length apo-B100 to form apo-B48. The recent observations of tumor formation in Apobec-1 transgenic animals, together with the fact that Apobec-1 is expressed in numerous tissues lacking apo-B, raises the issue of whether this enzyme is essential for a variety of posttranscriptional editing events. To directly test this, mice were created with a null mutation in Apobec-1 using homologous recombination in embryonic stem cells. Mice, homozygous for this mutation, were viable and made apo-B100 but not apo-B48. The null animals were fertile, and a variety of histological, behavioral, and morphological analyses revealed no phenotype other than abnormalities in lipoprotein metabolism, which included an increased low density lipoprotein fraction and a reduction in high density lipoprotein cholesterol. These studies demonstrate that neither apobec-1 nor apo-B48 is essential for viability and suggest that the major role of apobec-1 may be confined to the modulation of lipid transport.

Low density lipoproteins (LDL) heterogeneity and intravenous fat in neonates

BACKGROUND

The properties of iv-fat emulsions are similar to those of triglyceride-rich plasma lipoproteins and rapidly hydrolyzed by lipoprotein lipase. Neonates frequently do not tolerate iv-fat because of low levels of the key enzymes for fat metabolism.

PURPOSE OF THE STUDY

We examined the effect of iv-fat therapy on LDL subclass distribution of 20 neonates unable to tolerate enteral feeding.

METHODS

Particle size was determined by non-denaturing gradient gel electrophoresis.

RESULTS

The LDL size distribution profiles at baseline showed unexpected diversity in the position of the major lipoprotein peak with three different profiles identified by peak position; profile I with a major peak of large-sized LDL (26.3-28.2 nm), profile II with a major peak at 25.2-26.7 nm and profile III with a major peak of small-sized particles (24.9-25.6 nm). None of the profiles fit the classical LDL pattern A or B found in adult plasma since the skewness associated with the adult pattern was not present. With iv fat feeding and enteral nutrition, no major shift in peak position was observed, even though plasma triglyceride and apo B concentrations increased suggesting that there was an increased number of LDL particles rather than an increase in the size of particles.

CONCLUSION

The constancy of the LDL peak position in the face of increases in plasma triglyceride and apo B concentrations during iv fat and the onset of enteral nutrition in neonates suggests that other metabolic events, such as hormone status and lipid and transfer protein activities need to be considered.

Reversal of hypercholesterolemia in low density lipoprotein receptor knockout mice by adenovirus-mediated gene transfer of the very low density lipoprotein receptor

We have used the technique of adenovirus-mediated gene transfer to study the in vivo function of the very low density lipoprotein receptor (VLDLR) in low density lipoprotein receptor (LDLR) knockout mice. We generated a replication-defective adenovirus (AdmVLDLR) containing mouse VLDLR cDNA driven by a cytomegalovirus promoter. Transduction of cultured Hepa (mouse hepatoma) cells and LDLR-deficient CHO-ldlA7 cells in vitro by the virus led to high-level expression of immunoreactive VLDLR proteins with molecular sizes of 143 kDa and 161 kDa. Digestion of the cell extract with the enzymes neuraminidase, N-glycanase, and O-glycanase resulted in the stepwise lowering of the apparent size of the 161-kDa species toward the 143-kDa species. LDLR (-/-) mice fed a 0.2% cholesterol diet were treated with a single intravenous injection of 3 x 10(9) plaque-forming units of AdmVLDLR. Control LDLR (-/-) mice received either phosphate-buffered saline or AdLacZ, a similar adenovirus containing the LacZ cDNA instead of mVLDLR cDNA. Comparison of the plasma lipids in the 3 groups of mice indicates that in the AdmVLDL animals, total cholesterol is reduced by approximately 50% at days 4 and 9 and returned toward control values on day 21. In these animals, there was also a approximately 30% reduction in plasma apolipoprotein (apo) E accompanied by a 90% fall in apoB-100 on day 4 of treatment. By FPLC analysis, the major reduction in plasma cholesterol in the AdmVLDLR animals was accounted for by a marked reduction in the intermediate density lipoprotein/low density lipoprotein (IDL/LDL) fraction. Plasma VLDL, IDL/LDL, and HDL were isolated from the three groups of animals by ultracentrifugal flotation. In the AdmVLDLR animals, there was substantial loss (approximately 65%) of protein and cholesterol mainly in the IDL/LDL fraction on days 4 and 9. Nondenaturing gradient gel electrophoresis indicates a preferential loss of the IDL peak although the LDL peak was also reduced. When 125I-IDL was administered intravenously into animals on day 4, the AdmVLDLR animals cleared the 125I-IDL at a rate 5-10 times higher than the AdLacZ animals. We conclude that adenovirus-mediated transfer of the VLDLR gene induces high-level hepatic expression of the VLDLR and results in a reversal of the hypercholesterolemia in 0.2% cholesterol diet-fed LDLR (-/-, mice. The VLDLR overexpression appears to greatly enhance the ability of these animals to clear IDL, resulting in a marked lowering of the plasma IDL/LDL. Further testing of the use of the VLDLR gene as a therapeutic gene for the treatment of hypercholesterolemia is warranted.

Adenovirus-mediated gene transfer of rat apolipoprotein B mRNA-editing protein in mice virtually eliminates apolipoprotein B-100 and normal low density lipoprotein production

Apolipoprotein (apo) B-100 is the major protein component in low density lipoprotein (LDL); it contains the binding domain for the LDL receptor and the attachment site for apolipoprotein(a) in lipoprotein(a). ApoB-48 is colinear with the amino-terminal half of apoB-100 and misses the part of the molecule required for LDL receptor interaction and lipoprotein(a) formation. ApoB-48 mRNA is produced by the editing of apoB-100 mRNA, a process by which the codon CAA for Gln-2153 is changed to UAA, an in-frame stop codon. We used the cloned catalytic component of the rat apoB mRNA-editing enzyme (REPR) to construct a replication-defective recombinant adenoviral vector containing REPR cDNA (AvREPR) and a control vector (Av1LacZ4) containing a beta-galactosidase cDNA to investigate the effect of REPR gene delivery in C57BL/6 mice. Intravenous injection of AvREPR in mice resulted in efficient transduction of liver cells, where REPR mRNA and protein were overexpressed, reaching a peak at 7 and 12 days, returning toward control levels at 39 days after AvREPR administration. ApoB mRNA editing activity in liver extracts showed changes parallel to those of REPR mRNA expression; the proportion of edited apoB mRNA in the total hepatic apoB mRNA increased from approximately 60% to more than 90% at the peak of REPR expression. The proportion of plasma apoB-100 in AvREPR-transduced animals decreased from approximately 50% to < 10% of total plasma apoB concentration. Plasma very low density lipoproteins were polydisperse in control animals with an average diameter of 54.9 +/- 20.6 nm (uninjected control) and 54.7 +/- 16.8 nm (Av1LacZ4-treated), respectively. They became much smaller (average diameter 39.3 +/- 12.7 nm) and more uniform in size at day 12 following AvREPR administration. On the same day, the normal plasma LDL (26.2-25.5 nm) was almost completely eliminated in treated animals. Adenovirus-mediated transfer of the REPR cDNA is an efficient method to reduce plasma apoB-100 and normal LDL production.

Microcytic thrombocytosis, small megakaryocytes, platelet lipids and hyperreactivity to collagen, lymphocytopenia, eosinophilia, and low blood volume in genetically hyperlipidemic rabbits

Three- to 15-month-old rabbits with Watanabe heritable hyperlipidemia (WHHL) were tested to determine if hematological abnormalities would accompany the known hyperlipidemia and deficiency of receptors for low-density lipoprotein; the findings were compared to those of New Zealand white (NZW) rabbits of the same ages. WHHL plasma cholesterol and triglyceride levels were always greater than or equal to 6x those of NZW, and both were lower in older than in younger WHHL rabbits. From age 7 to 18 months, WHHL platelet counts were higher than those of age-matched NZW; the average for all WHHL was 1.45x that for NZW (p = 0.001). Average WHHL mean platelet volume (MPV) was 0.94x that for NZW (p = 0.025), with a tendency for greater microcytosis to occur at more advanced ages; electron microscopy supported the small size of WHHL platelets. WHHL platelet mass per microliter of blood (platelet count x MPV) was 1.39x that of NZW (p = 0.001), with differences occurring after the age of 6 months. The average WHHL blood volume was 18.3% less than in NZW (33.5 vs 41.0 ml/kg body weight) (p = 0.00005), so platelet count and mass per kilogram of body weight were similar in the two strains. The predominant ploidy of mature megakaryocytes from each strain was 32N; megakaryocytes were smaller in WHHL than NZW due to a smaller size of 32N cells (p = 0.002). Total leukocyte counts were the same in WHHL and NZW rabbits, but eosinophils were 32% higher (p = 0.037) and lymphocytes 34% lower (p = 0.008) in WHHL. Hematocrits and reticulocytes did not differ. Platelet-free cholesterol was 1.2x, esterified cholesterol 11.3x, phospholipids 0.9x, triglyceride 2.4x, and free cholesterol/phospholipid molar ratio 1.29x corresponding values in NZW platelets. WHHL platelets released more serotonin in response to a small dose (5 micrograms/ml) of collagen than did NZW platelets. These findings suggest that: 1) megakaryocytopoiesis and leukopoiesis are affected by lipid metabolism and/or LDL receptors, and 2) platelet production may be regulated more by the total mass of platelets than by their concentration in the blood.

Iron-induced ascorbate oxidation in plasma as monitored by ascorbate free radical formation. No spin-trapping evidence for the hydroxyl radical in iron-overloaded plasma

A study was made of the interaction of plasma ascorbate and ascorbate free radical (AFR) with exogenously added iron. The quantitative determination of AFR has the advantage that transient increases in ascorbate oxidation can be directly monitored by e.p.r. spectroscopy. An AFR signal was found in the plasma of all donors and was unaffected by superoxide dismutase, catalase and the strong iron chelator deferoxamine. These findings and the rapid decrease in AFR under a nitrogen atmosphere suggest that plasma AFR is probably a result of air auto-oxidation. Iron loading of plasma did not affect the intensity of the AFR signal until the iron concentration approached or exceeded the plasma latent iron-binding capacity. In iron-overloaded plasma, the intensity of the AFR signal increased to about 10 times the normal level before decreasing rapidly to undetectable levels after 15-20 min. Determination of plasma ascorbate showed that the disappearance of AFR was due to a complete loss of the vitamin. When 50 microM-ascorbate was loaded with iron in iso-osmotic phosphate buffer there was an increase in the AFR signal, independent of the iron concentration, which was stable at least for 15 min. Thus the rate of ascorbate loss in the iso-osmotic phosphate buffer was considerably lower than in iron-overloaded plasma. The addition of different iron chelators produced comparable effects on the intensity of the AFR signal in both iron-overloaded plasma and ascorbate solution. These results suggest that the characteristic behaviour of plasma AFR after iron loading is due to its specific iron-binding capacity and to plasma ferroxidase activity. The ferroxidase activity of plasma is important to promote the transfer of Fe2+ into transferrin without a transient ascorbate oxidation. Spin-trapping studies with 5,5-dimethyl-1-pyrroline N-oxide and N-t-butyl-alpha-phenylnitrone revealed that iron-overloaded plasma was unable to produce spin-trap adducts even in the presence of 50-300 microM-hydrogen peroxide or 100 microM-azide. Evidence of OH. radical formation was obtained only after the addition of EDTA. Therefore, iron-overloaded plasma itself does not produce a Fenton reaction and, if ascorbate does indeed have a free-radical-mediated pro-oxidant role, it is not detectable in plasma by spin-trapping experiments.

Recycling of vitamin E in human low density lipoproteins

Oxidative modification of low density lipoproteins (LDL) and their unrestricted scavenger receptor-dependent uptake is believed to account for cholesterol deposition in macrophage-derived foam cells. It has been suggested that vitamin E that is transported by LDL plays a critical role in protecting against LDL oxidation. We hypothesize that the maintenance of sufficiently high vitamin E concentrations in LDL can be achieved by reducing its chromanoxyl radicals, i.e., by vitamin E recycling. In this study we demonstrate that: i) chromanoxyl radicals of endogenous vitamin E and of exogenously added alpha-tocotrienol, alpha-tocopherol or its synthetic homologue with a 6-carbon side-chain, chromanol-alpha-C6, can be directly generated in human LDL by ultraviolet (UV) light, or by interaction with peroxyl radicals produced either by an enzymic oxidation system (lipoxygenase + linolenic acid) or by an azo-initiator, 2,2'-azo-bis(2,4-dimethylvaleronitrile) (AMVN; ii) ascorbate can recycle endogenous vitamin E and exogenously added chromanols by direct reduction of chromanoxyl radicals in LDL; iii) dihydrolipoic acid is not efficient in direct reduction of chromanoxyl radicals but recycles vitamin E by synergistically interacting with ascorbate (reduces dehydroascorbate thus maintaining the steady-state concentration of ascorbate); and iv) beta-carotene is not active in vitamin E recycling but may itself be protected against oxidative destruction by the reductants of chromanoxyl radicals. We suggest that the recycling of vitamin E and other phenolic antioxidants by plasma reductants may be an important mechanism for the enhanced antioxidant protection of LDL.

Generation of probucol radicals and their reduction by ascorbate and dihydrolipoic acid in human low density lipoproteins

Probucol, 4,4'-[(1-methylethylidene)bis(thio)]bis-[2,6-bis(1,1- dimethyl)phenol], is a lipid regulating drug whose therapeutic potential depends on its antioxidant properties. Probucol and alpha-tocopherol were quantitatively compared in their ability to scavenge peroxyl radicals generated by the thermal decomposition of the lipid-soluble azo-initiator 2,2'-azo-bis(2,4-dimethyl-valeronitrile), AMVN, in dioleoylphosphatidylcholine (DOPC) liposomes. Probucol showed 15-times lower peroxyl radical scavenging efficiency than alpha-tocopherol as measured by the effects on AMVN-induced luminol-dependent chemiluminescence. We suggest that probucol cannot protect alpha-tocopherol against its loss in the course of oxidation, although probucol is known to prevent lipid peroxidation in membranes and lipoproteins. In human low density lipoproteins (LDL) ESR signals of the probucol phenoxyl radical were detected upon incubation with lipoxygenase + linolenic acid or AMVN. Ascorbate was shown to reduce probucol radicals. Dihydrolipoic acid alone was not able to reduce the probucol radical but in the presence of both ascorbate and dihydrolipoic acid a synergistic effect of a stepwise reduction was observed. This resulted from ascorbate-dependent reduction of probucol radicals and dihydrolipoic acid-dependent reduction of ascorbyl radicals. The oxidized form of dihydrolipoic acid, thioctic acid, did not affect probucol radicals either in the presence or in the absence of ascorbate.

Oxidative stress and abnormal cholesterol metabolism in patients with adult respiratory distress syndrome

Oxidative stress has been implicated in the adult respiratory distress syndrome (ARDS). In this study, we determined the levels of selected antioxidants in the plasma of 25 patients with ongoing ARDS and 16 healthy control subjects. We also examined these plasmas and pulmonary edema fluid of ARDS patients for lipid hydroperoxides. Both ascorbate and ubiquinol-10 concentrations in ARDS plasma were significantly lower than in normal plasma. alpha-Tocopherol concentrations, when standardized to total plasma cholesterol, were not lower in ARDS patients than in normal subjects. A pattern of antioxidant levels virtually identical to that observed in ARDS plasma was obtained after in vitro incubation of healthy plasma with stimulated polymorphonuclear leukocytes: very low ascorbate, decreased ubiquinol-10, and unchanged alpha-tocopherol concentrations. Nanomolar concentrations of lipid hydroperoxides were found in pulmonary edema fluid of ARDS patients, but not in plasma, nor in the plasma of healthy individuals, when a sensitive and selective chemiluminescence assay for hydroperoxides was used. ARDS patients also showed significant decreases in plasma levels of cholesterol esters in conjunction with discoidal high-density lipoprotein profiles, indicating a decrease in lecithin-cholesterol acyltransferase activity. We conclude that ARDS is associated with oxidative stress, possibly exerted by oxidants released from activated phagocytic leukocytes, and major changes in plasma cholesterol metabolism.

Apolipoprotein B-100 Hopkins (arginine4019----tryptophan). A new apolipoprotein B-100 variant in a family with premature atherosclerosis and hyperapobetalipoproteinemia

A 43-year-old woman with severe coronary artery disease and hyperapobetalipoproteinemia was heterozygous for an abnormal Msp I apolipoprotein B (APOB) gene fragment because of the absence of the MspI site around codon 4046 in exon 29 of the APOB gene. Using the polymerase chain reaction technique, 134 base pairs containing the mutant Msp I site were amplified, cloned, and sequenced. The mutation was a C to T transition, substituting tryptophan for arginine at amino acid position 4019 of the mature ApoB-100 protein. Seven relatives of the proband had the same mutation, which has been called "ApoB-100 Hopkins." Only three of seven relatives with the mutation had hyperapobetalipoproteinemia; one was borderline while two other relatives without the mutation had hyperapobetalipoproteinemia. Mutant low-density lipoprotein (LDL) was bound and degraded to a greater extent than normal LDL in cultured human fibroblasts. In conclusion, a new mutation, ApoB-100 Hopkins, was not linked to the hyperapobetalipoproteinemia phenotype, which also was segregating in this family. The increased affinity of this mutant LDL for the LDL receptor may be due to a specific effect of ApoB-100 Hopkins or to altered LDL size and composition.

Thermal properties of red blood cells infected by malaria parasites

Three membrane thermotropic transitions at 8, 20, and 40 degrees C have been detected in human red blood cells (RBC) by using spin-labeled stearic acids. Red blood cells infected in vitro by Plasmodium falciparum showed the disappearance of the 8 degrees C transition and a lowering of the 40 degrees C transition to 32 degrees C. The disappearance of the 8 degrees C transition was observed in synchronized cultures of P. falciparum trophozoites as well as in mouse RBC infected in vivo by an asynchronous population of P. berghei. Furthermore, erythrocytes infected by P. falciparum showed an increase in the phosphorylation of protein 4.1. This protein was shown previously to be involved in the 8 degrees C transition, (T. Forte, T. L. Leto, M. Minetti, and V. T. Marchesi, Biochemistry 24, 7876-7880 (1985). Our results suggest that the malaria parasite invasion produces a disorganization of the protein 4.1-membrane interaction.

Increased sitosterol absorption, decreased removal, and expanded body pools compensate for reduced cholesterol synthesis in sitosterolemia with xanthomatosis

We measured the turnover and absorption of sitosterol and cholesterol, along with plasma sterol and lipoprotein concentrations, in one control and two subjects with sitosterolemia with xanthomatosis. All individuals consumed the same diet which contained approximately 500 mg/day of cholesterol and 250 mg/day of sitosterol. Sterol absorption was measured by the plasma dual-isotope ratio method and turnover by plasma isotope-kinetic analysis. In two sitosterolemic subjects, 28% and 63% of the sitosterol and 69% and 49% of the cholesterol were absorbed, respectively, compared to 4% of the sitosterol and 44% of the cholesterol in the control. As expected, plasma sitosterol specific activities decayed much more rapidly than cholesterol in the control subject. In contrast, plasma sitosterol and cholesterol specific activity-time curves were similar and decayed more slowly in the sitosterolemic subjects. In the control subject, the total sitotterol pool was 290 mg and was linearly related to low absorption (18 mg/day); whereas the total sitosterol pool was 17 times (4800 mg) and 13 times (3500 mg) larger, respectively, in the sitosterolemic subjects and was expanded out of proportion to increased absorption because of decreased removal. Daily cholesterol turnover and synthesis were markedly reduced in the sitosterolemic subjects. In four sitosterolemic subjects, plasma concentrations of total sterols, low density lipoproteins, and apolipoprotein B were increased, while those of high density lipoproteins and apolipoprotein A-I were low to normal. The low density lipoproteins were very similar to those of normal control subjects in density distribution, peak flotation rate, sterol-to-protein (apolipoprotein B) ratio, particle size, and morphology. These results demonstrate in patients with sitosterolemia with xanthomatosis that: 1) the absorption of sitosterol and cholesterol is enhanced; 2) tissue recognition between cholesterol and sitosterol is lost; 3) total exchangeable sitosterol pools are expanded out of proportion to absorption because of decreased excretion; 4) plasma sterol and lipoprotein concentrations favor tissue deposition; and 5) cholesterol synthesis is diminished. We postulate that the changes in sitosterol metabolism (increased absorption, loss of tissue sterol structural recognition, expanded pools, and hepatic retention) are a response to reduced cholesterol synthesis in these subject.

Hyperapobetalipoproteinemia in a kindred with familial combined hyperlipidemia and familial hypercholesterolemia

A child showed a type IIb lipoprotein pattern and triglyceride-enriched cutaneous xanthomas before 1 year of age. The proband and 9 of 18 relatives had elevated plasma levels of low density lipoprotein (LDL) B protein; of these nine relatives, four had elevated LDL of increased density while five had elevated LDL of normal density. Compared with normal LDL, LDL of increased density had less cholesteryl ester and free cholesterol, more apolipoprotein B and triglyceride, and a lower molecular weight and flotation rate (Sf degrees). Patients with LDL of increased density had higher mean plasma levels of triglycerides, very low density lipoproteins, and intermediate density lipoproteins, but lower levels of high density lipoproteins than those with elevated LDL of normal density. Multiple lipoprotein patterns in the father's family suggested the presence of familial combined hyperlipidemia (FCH). The mother of the proband and two of her relatives had type IIa lipoprotein patterns and tendon xanthomas, compatible with familial hypercholesterolemia (FH). High affinity binding, internalization, and degradation of 125I LDL in cultured fibroblasts from the proband and his mother were reduced two- to threefold compared with normal cells, while LDL receptor activity in the proband's father was normal. This unusual proband has apparently inherited both FCH and FH.

Protein 4.1 is involved in a structural thermotropic transition of the red blood cell membrane detected by a spin-labeled stearic acid

Proteins involved in a structural transition in red blood cell membranes detected at 8 +/- 1.5 degrees C by a stearic acid spin-label have been investigated. Calcium loading of red blood cells with ionophore A23187 caused the disappearance of the 8 degrees C transition. Protein 4.1 appears to be the most susceptible protein to Ca2+ treatment. Antibodies specific for spectrin, band 3 (43K cytoplasmic domain), and protein 4.1 have been utilized as specific probes to modify membrane thermotropic properties. The 8 degrees C transition was eliminated by anti-4.1 protein antibodies but was not modified by the other antibodies. To further characterize the protein(s) involved in the transition, ghosts were subjected to sequential extraction of skeletal proteins. The extraction of band 6, spectrin, and actin did not modify the 8 degrees C transition. In contrast, high-salt extraction (1 M KCl) of spectrin-actin-depleted vesicles, a procedure that extracts proteins 2.1 and 4.1, was able to eliminate the 8 degrees C transition. Rebinding of purified protein 4.1 to the high salt extracted vesicles restored the 8 degrees C transition. These results indicate the involvement of protein 4.1 in the transition and suggest a functional membrane association of this protein. The binding of protein 4.1 to the membrane seems to contribute significantly to the thermotropic properties of red blood cells.

Intestinal lymph lipoproteins in rats fed diets enriched in specific fatty acids

Four groups of rats were fed test diets with fats providing 75% of fatty acids as palmitate, stearate, oleate or linoleate. Absorption of radiolabeled cholesterol and the specific triglyceride into intestinal lymph lipoproteins and the lipid and protein content and composition of intestinal lymph were compared. Cholesterol and triglyceride absorptions were correlated significantly and were less with the saturated fatty acid diets. The fatty acid patterns of triglyceride-rich lymph lipoproteins mirrored the diet. Exogenous cholesterol was recovered primarily in chylomicrons, except with linoleate. In contrast, radiolabeled saturated fatty acids were recovered primarily in very low density lipoproteins and unsaturated fatty acids were recovered in chylomicrons. Lymph chylomicron size and lipid content were greater with unsaturated fat diets. Triglyceride-rich intestinal lipoproteins of rats fed saturated fats were polygonal by electron microscopy, related to the cooling of lymph samples below body temperature. A-I apolipoproteins were increased in relation to C apoproteins as lipid absorption was greater. Plasma triglycerides in all groups increased compared to rats fed the stock diet. A diet enriched in one specific fatty acid has its unique effects on lymph lipoprotein formation presumably affecting some intestinal subcellular mechanisms. Diet-induced changes in plasma lipids and lipoproteins are not directly related to these as yet unknown mechanisms.

Interaction of the serum amyloid A proteins with phospholipid

The serum amyloid A proteins (SAA) are transported in plasma in association with the high density lipoproteins. We have studied the solution properties of two of the polymorphic forms of SAA, SAA1 and SAA4, and compared the lipid-binding properties of SAA4 to those of the well characterized apolipoproteins, apo-A-I, apo-A-II, and apo-C-III. SAA4 was monomeric at pH 2.9 but considerable self-association was demonstrated at pH 8.2, even in the presence of 1.0 M guanidine HCl. SAA4 differed from the apolipoproteins in its ability to disrupt multilamellar dimyristoylphosphatidylcholine (DMPC) liposomes and generate bilayer discs. Apo-A-I, apo-A-II, and apo-C-III reduced the turbidity of DMPC dispersions at protein:lipid molar ratios of 1:200. SAA4, however, increased turbidity at molar ratios of 1:250 and 1:100 even when preincubated in guanidine HCl before addition to liposomes. Optical density decreased only at ratios of 1:50 and 1:25. At an SAA4:DMPC ratio of 1:50, discoidal particles (long axis, 28.1 nm; short axis, 4.4 nm) were formed which were similar to those produced by apo-C-III. Lipid binding induced changes in SAA4 conformation similar to those observed in the apolipoproteins. The alpha-helical content and intrinsic tryptophanyl fluorescence were increased and quenching of tryptophanyl fluorescence by acrylamide was reduced in the presence of DMPC. In addition, SAA4 as well as the apolipoproteins broadened the range and increased the temperature of the gel-liquid crystal transition temperature of DMPC.

Dietary saturated fatty acid content affects lymph lipoproteins: studies in the rat

We examined effects on intestinal absorption of cholesterol and triglycerides and intestinal lipoprotein formation by feeding rats diets in which saturated fatty acids (palmitic plus stearic) comprised 78%, 68%, 48%, or 38% of triglyceride fatty acids. Absorption into lymph of radiolabeled cholesterol was proportional to triglyceride absorption. The rates of absorption of these lipids were related inversely to the % saturated fatty acids fed. The distribution of newly absorbed cholesterol and triglyceride into intestinal lipoproteins differed. With increasing cholesterol absorption more was recovered in very low density lipoproteins in contrast to the appearance preferentially in chylomicrons of larger quantities of fatty acid. Lymph lipid content did not reflect a consistent pattern in relation to the experimental diet fed. The fatty acid composition of triglyceride-rich lymph lipoproteins resembled the diet closely. One-quarter of the intestinal lymph particles from rats fed the highly saturated diets was flattened and polygonal as judged by electron microscopy if cooled to room temperature; whereas with the same diets, particles collected and isolated at 37 degrees C were round. Proportions of A-I and C apolipoproteins in triglyceride-rich intestinal particles varied inversely; apoA-I increased as fat/cholesterol absorption was greater. Diet-induced alterations in plasma lipoproteins and increased circulating triglycerides in this study in rats were unrelated to the variations in intestinal absorption or lymph lipoprotein formation.

Further studies and electron microscopic characterization of Plasmodium berghei DNA

The average length and the interspersion pattern of repetitive DNA sequences in the Plasmodium berghei genome have been studied by electron microscopy. Within the limitations posed by the relatively high genome complexity, analysis of partially renatured total DNA indicates that repetitive sequences do not occupy preferential positions along the genome, but are widely dispersed (one in approx. 8000 base pairs of unique DNA). Structures appearing as loops flanked by inverted repeats are present. Analysis of the repetitive fraction purified by hydroxyapatite chromatography shows that the average length of rapidly reassociating repetitive structures is around 800 base pairs with 90% of the length distribution between 400 and 1400 base pairs. Suitable extraction methods, preserving circularity of extrachromosomal DNA components, allow the detection of molecules which can be identified as mitochondrial DNA, 10.5 +/- 0.4 microns long.

Physical studies of d less than 1.006 g/ml lymph lipoproteins from rats fed palmitate-rich diets

At body temperature the stable form of triglycerides rich in saturated fatty acids is crystalline. We examined the physical state of triglyceride-rich lymph lipoproteins from rats fed saturated fat, as a function of temperature. When chylomicrons and very low density lipoproteins were collected, isolated, and examined at 37 degrees C, they were liquid as judged by differential scanning calorimetry, x-ray diffraction analysis and proton nuclear magnetic resonance spectroscopy, and they appeared spherical by electron microscopy. At 23-26 degrees C, triglyceride began to crystallize in the alpha form, which transformed to the stable beta form at lower temperatures. On cooling from 23 degrees C to 17 degrees C, considerable crystallization occurred and the particle density was increased significantly. When lipoproteins were held at 0-7 degrees C, about 75% of the triglyceride crystallized, distorting the lipoprotein shape. Reheating from 0 degrees C to 37 degrees C left 25% of the triglyceride unmelted. Heating to 58 degrees C was necessary to melt all the crystallized triglyceride and to restore the spherical lipoprotein shape. After complete melting of cooled lipoproteins, the liquid state was maintained on recooling to 37 degrees C, with formation of a metastable particle similar to the nascent lipoprotein. Isolation of lipoproteins containing highly saturated triglyceride at temperatures below 23-26 degrees C results in partial crystallization, alters their physical properties, and may affect their metabolism.