Journey to the center of the category: the dissociation in amnesia between categorization and recognition

The authors' theoretical analysis of the dissociation in amnesia between categorization and recognition suggests these conclusions: (a) Comparing to-be-categorized items to a category center or prototype produces strong prototype advantages and steep typicality gradients, whereas comparing to-be-categorized items to the training exemplars that surround the prototype produces weak prototype advantages and flat typicality gradients; (b) participants often show the former pattern, suggesting their use of prototypes; (c) exemplar models account poorly for these categorization data, but prototype models account well for them; and (d) the recognition data suggest that controls use a single-comparison exemplar-memorization process more powerfully than amnesics. By pairing categorization based in prototypes with recognition based in exemplar memorization, the authors support and extend other recent accounts of cognitive performance that intermix prototypes and exemplars, and the authors reinforce traditional interpretations of the categorization-recognition dissociation in amnesia.

First Report of Dollar Spot, Caused by Sclerotinia homoeocarpa, on Poa pratensis in Saskatchewan, Canada

Dollar spot disease affects many species of grasses in North America but has not been previously reported from Saskatchewan. In July 2000, symptoms were observed on golf course fairways in Saskatoon. No dollar spot disease was observed on adjacent putting greens or tees composed of Agrostis palustris (creeping bentgrass), perhaps because the tees and greens were grown under a higher nitrogen fertility regime. Fungicide treatments are usually not required for turf disease control during the warm, dry summer growing season in Saskatoon, and no fungicides had been applied at this location. Daytime temperatures near 25°C and heavy dew at night preceded the disease outbreak, which affected about 5% of the turf across large areas of several fairways. The fairways were originally seeded to Festuca rubra subsp. rubra (common creeping red fescue) and Poa pratensis (Kentucky bluegrass) but also contained annual bluegrass (P. annua). The disease was observed on leaf blades of all three species. In addition to 5-cm-diameter circular patches of brown grass, sharply delimited individual leaf lesions and cobweb-like aerial mycelia on the grass were observed. Fungal isolates were obtained by plating infected P. pratensis leaf blades on potato dextrose agar and then transferring to oat agar. On oat agar, isolates produced white, fluffy aerial mycelium, columnar when mature, and usually with a cinnamon base and dark brown stromata or sclerotial flakes on and in the agar. DNA was extracted from an isolate and amplified using the primers ITS1 and ITS4 (1). A 500-bp fragment presumed to contain the internal transcribed spacer region of the ribosomal DNA (ITS) was purified and sequenced (1), and it showed 96% identity with the ITS of a Sclerotinia homoeocarpa isolate, Genbank accession AF067640. To test Koch's postulates, P. pratensis cv. Loft 1757 was grown from seed in 15 ml of sand at 20°C under constant fluorescent light. Two-week-old turf was inoculated with 5-mm-diameter mycelial plugs of the fungus from 1-week-old cultures on potato dextrose agar by placing inoculum plugs on the sand. Inoculated turf was incubated in a loosely-lidded clear plastic container at 20°C under constant fluorescent lighting. After 1 week, lesions and white aerial hyphae were observed on the leaf blades, while no disease was observed on the uninoculated controls. The fungus was reisolated from foliar lesions to complete Koch's postulates. In addition to P. pratensis, both P. annua and A. palustris cv. Penncross were also inoculated and showed disease symptoms, with greater disease severity on P. annua. Reference: (1) T. Hsiang and C. Wu. Mycol. Res. 104:16, 2000.

Erectile dysfunction in chronic peritoneal dialysis patients: incidence and treatment with sildenafil

OBJECTIVES

Sexual and erectile dysfunction (ED) have been reported to occur frequently in male patients with end-stage renal disease maintained on dialysis. Numerous etiologies for this ED have been suggested. Although a variety of therapies for the ED of the dialysis patient have been suggested, most clinicians indicate that patients report a poor response to therapy. Recently, sildenafil has been reported to be beneficial in treating patients with ED of both organic and psychogenic causes. The present study was designed to document the incidence of ED in male patients maintained on chronic peritoneal dialysis (CPD) and to determine the efficacy of prescribing sildenafil therapy to treat their ED.

METHODS

All male patients in our CPD unit were notified by letter of the availability of sildenafil as a treatment modality for ED. A sexuality/erectile dysfunction assessment was conducted in all male patients by their primary nephrologist. Patients who reported ED and who had no medical contraindication to sildenafil were offered this therapy. Those patients who were interested in this treatment were interviewed by a social worker, and patients were asked to complete the International Index of Erectile Function questionnaire. Sildenafil was prescribed at a starting dose of 25 mg and increased to a maximum of 100 mg during a 12-week study trial. Patients were re-evaluated 6 and 12 weeks after the start of therapy.

RESULTS

There were 68 male patients maintained on CPD at the time of the study. Mean age of all patients was 60.8 +/- 15.3 years and mean duration on PD was 32.6 +/- 25.6 months. Thirty-three patients had diabetes, 66 hypertension, 35 peripheral vascular disease, and 32 coronary artery disease. Thirty-two of 68 male patients in the CPD unit were assessed to have ED. Only 17 of the 32 patients expressed interest in pursuing sildenafil therapy. Two of these patients were excluded because they were receiving nitrate therapy. Of the 15 patients who agreed to take sildenafil, only 6 completed the 12-week study. Two of these patients responded to sildenafil.

CONCLUSION

Erectile dysfunction is common in male patients maintained on CPD. Only about half of patients with ED in the present study were willing to consider sildenafil therapy to treat the ED and, of those who agreed to treatment, only a minority completed the 12-week trial; 2 of these 6 patients reported a satisfactory response.

Relief of fibromyalgia symptoms following discontinuation of dietary excitotoxins

BACKGROUND

Fibromyalgia is a common rheumatologic disorder that is often difficult to treat effectively.

CASE SUMMARY

Four patients diagnosed with fibromyalgia syndrome for two to 17 years are described. All had undergone multiple treatment modalities with limited success. All had complete, or nearly complete, resolution of their symptoms within months after eliminating monosodium glutamate (MSG) or MSG plus aspartame from their diet. All patients were women with multiple comorbidities prior to elimination of MSG. All have had recurrence of symptoms whenever MSG is ingested.

DISCUSSION

Excitotoxins are molecules, such as MSG and aspartate, that act as excitatory neurotransmitters, and can lead to neurotoxicity when used in excess. We propose that these four patients may represent a subset of fibromyalgia syndrome that is induced or exacerbated by excitotoxins or, alternatively, may comprise an excitotoxin syndrome that is similar to fibromyalgia. We suggest that identification of similar patients and research with larger numbers of patients must be performed before definitive conclusions can be made.

CONCLUSIONS

The elimination of MSG and other excitotoxins from the diets of patients with fibromyalgia offers a benign treatment option that has the potential for dramatic results in a subset of patients.

Anesthesia-associated carbon monoxide exposures among surgical patients

OBJECTIVE

To estimate the extent of, and evaluate risk factors for, elevated carboxyhemoglobin levels among patients undergoing general anesthesia and to identify the source of carbon monoxide.

DESIGN

Matched case-control study to measure carboxyhemoglobin levels.

SETTING

Large academic medical center.

PARTICIPANTS

45 surgical patients who underwent general anesthesia

RESULTS

Case-patients were more likely than controls to undergo surgery on Monday or Tuesday (10/15 vs 7/30; matched odds ratio [mOR], 7.7; 95% confidence interval [CI95], 1.8-34; P=.01), in one particular room (7/15 vs 4/30; mOR, 8.5; CI95, 1.5-48; P=.03) or in a room that was idle for > or =24 hours (11/15 vs 1/30; mOR, 95.5; CI95, 8.0-1,138; P< or =.001). In a multivariate model, only rooms, and hence the anesthesia equipment, that were idle for > or =24 hours were independently associated with elevated intraoperative carboxyhemoglobin levels (OR, 22.4; CI95, 1.5-338; P=.025). Moreover, peak carboxyhemoglobin levels were correlated with the length of time that the room was idle (r=0.7; CI95, 0.3-0.9). Carbon monoxide was detected in the anesthesia machine outflow during one case-procedure. No contamination of anesthesia gas supplies or CO2 absorbents was found.

CONCLUSIONS

Carbon monoxide may accumulate in anesthesia circuits left idle for > or =24 hours as a result of a chemical interaction between CO2-absorbent granules and anesthetic gases. Patients administered anesthesia through such circuits may be at increased risk for elevated carboxyhemoglobin levels during surgery or the early postoperative period.

Modifications in the CD36 binding domain of the Plasmodium falciparum variant antigen are responsible for the inability of chondroitin sulfate A adherent parasites to bind CD36

Adhesion of mature Plasmodium falciparum parasitized erythrocytes to microvascular endothelial cells or to placenta contributes directly to the virulence and severe pathology of P falciparum malaria. Whereas CD36 is the major endothelial receptor for microvasculature sequestration, infected erythrocytes adhering in the placenta bind chondroitin sulfate A (CSA) but not CD36. Binding to both receptors is mediated by different members of the large and diverse protein family P falciparum erythrocyte membrane protein-1 (PfEMP-1) and involves different regions of the molecule. The PfEMP-1-binding domain for CD36 resides in the cysteine-rich interdomain region 1 (CIDR-1). To explore why CSA-binding parasites do not bind CD36, CIDR-1 domains from CD36- or CSA-binding parasites were expressed in mammalian cells and tested for adhesion. Although CIDR-1 domains from CD36-adherent strains strongly bound CD36, those from CSA-adherent parasites did not. The CIDR-1 domain has also been reported to bind CSA. However, none of the CIDR-1 domains tested bound CSA. Chimeric proteins between CIDR-1 domains that bind or do not bind CD36 and mutagenesis experiments revealed that modifications in the minimal CD36-binding region (M2 region) are responsible for the inability of CSA-selected parasites to bind CD36. One of these modifications, mapped to a 3-amino acid substitution in the M2 region, ablated binding in one variant and largely reduced binding of another. These findings provide a molecular explanation for the inability of placental sequestered parasites to bind CD36 and provide additional insight into critical residues for the CIDR-1/CD36 interaction.

The financial implications of HMOs' partial county carve-out option

This study examined the Health Care Financing Administration's policy allowing Medicare HMO risk contracts to carve out certain portions of counties from their service areas without adjusting the HMOs' capitation rate. In 1999, the policy resulted in 2.2 million Medicare enrollees losing access to HMOs and 2.3 million Medicare enrollees left with fewer HMO options. Although the majority of Medicare HMOs did not appear to be adopting the policy, there did seem to be a general tendency to exclude higher cost areas, which resulted in an estimated loss to the Medicare Trust Fund of $769 million in 1999. Of particular concern is the magnitude of profits and losses this policy generated for some individual HMOs.

Cocaine decreases cell survival and inhibits neurite extension of rat locus coeruleus neurons

Cocaine use during pregnancy is affiliated with neurobehavioral abnormalities in offspring that are associated with problems of attention. Given the putative role of the noradrenergic system in attentional processes, impairments in the noradrenergic system may underlie specific attentionally sensitive, neurobehavioral alterations. Recent data using a clinically relevant intravenous (iv) route of administration show that the norepinephrine cell bodies of the locus coeruleus (LC) are a primary target for in utero cocaine exposure. Cell survival and neurite outgrowth of LC neurons were studied using two paradigms: (1) in vitro, using a physiologically relevant concentration of cocaine, and (2) in vivo, using a clinically relevant intravenous rat model. Fetal cocaine exposure significantly decreased neuronal survival (in vitro: P=.0001, n=24; in vivo: P=.0337, n=30), reduced neurite initiation (in vitro: P=.001, n=24; in vivo: P=.0169, n=30), decreased the number of neurites elaborated (in vivo: P=.0031, n=30), and reduced total neurite length (in vivo: P=.0237, n=30). The results of this novel approach toward an understanding of noradrenergic neurons as they respond to cocaine during development suggest that cocaine may affect behavior by negatively regulating neuronal pathfinding and synaptic connectivity.

Up‐regulation of endoglin, a TGF‐β‐binding protein, in rats with experimental renal fibrosis induced by renal mass reduction

BACKGROUND

The central process in chronic renal failure is the progressive accumulation of extracellular matrix in the glomeruli and in the tubulo-interstitial space, resulting in renal fibrosis. Transforming growth factor-beta1 (TGF-beta1) up-regulation plays a major role in the genesis of renal fibrosis. Endoglin is a membrane glycoprotein that binds TGF-beta1 and TGF-beta3 with high affinity. An increased level of endoglin immunostaining has been demonstrated previously in biopsies from patients with chronic progressive renal disease. We have assessed the expression of endoglin in the rat 5/6th renal mass reduction (RMR) model.

METHODS

One, 3 and 5 months after RMR, mean arterial pressure and renal function were measured, animals were sacrificed, renal fibrosis was evaluated quantitatively and the expression of endoglin was assessed by western blot, northern blot and immunohistochemistry.

RESULTS

RMR induced a progressive increase in mean arterial pressure and urinary protein excretion. Renal corpuscular area, and mesangial and interstitial fibrosis increased with time after RMR. Immunohistochemical staining for endoglin demonstrated its expression mainly on the endothelial surface of major vessels. In kidneys 1 and 3 months after RMR, the expression of endoglin in renal corpuscles was limited to Bowman's parietal epithelium. In rats 5 months after RMR, the immunoexpression in glomerular endothelium was more marked. Northern blot analysis revealed that rats with RMR showed an increase in the expression of mRNA for endoglin, only at 5 months after RMR. Western blot analysis gave a different time course: a marked increase in the first month, a decrease in the 3rd month and a further increase in the 5th month after RMR.

CONCLUSIONS

The present study demonstrates increased endoglin expression in rats with severe hypertension and renal damage. This increased endoglin expression coincides with the period of higher renal damage and renal dysfunction.

Prototypes in category learning: the effects of category size, category structure, and stimulus complexity

Although research in categorization has sometimes been motivated by prototype theory, recent studies have favored exemplar theory. However, some of these studies focused on small, poorly differentiated categories composed of simple, 4-dimensional stimuli. Some analyzed the aggregate data of entire groups. Some compared powerful multiplicative exemplar models to less powerful additive prototype models. Here, comparable prototype and exemplar models were fit to individual-participant data in 4 experiments that sampled category sets varying in size, level of category structure, and stimulus complexity (dimensionality). The prototype model always fit the observed data better than the exemplar model did. Prototype-based processes seemed especially relevant when participants learned categories that were larger or contained more complex stimuli.

Apolipoprotein E deficiency effects on learning in mice are dependent upon the background strain

Apolipoprotein E (apoE) deficient mice were bred onto the C57BL/6 and FVB/N strain backgrounds. The cognitive behavior of food-restricted apoE-deficient and wildtype male mice from these strains was assessed in an olfactory cued 8-arm radial maze. At 6 weeks of age, all four types of mice improved in maze performance over the course of 5 days. However, at 6 months of age, only the apoE-deficient mice on the C57BL/6 background failed to improve their maze performance over the 5 day course, as gauged by the number of incorrect choices made before retrieving both food rewards. Thus, an age-dependent and strain-specific effect of apoE deficiency on cognitive behavior was observed in these mice. The background strain affected activity levels in the maze, as well as in an open field assay. Plasma corticosterone levels were assessed in control, fasted, and post-restraint stress states. Fasting and restraint stress led to increases in plasma corticosterone levels. Although there were strain specific effects on fasting corticosterone levels, and the effect of apoE deficiency on post-stress corticosterone levels, there was no association between fasted corticosterone levels and impaired cognitive behavior in the 8-arm radial maze assay.

ANTIVIMENTIN ANTIBODIES ARE AN INDEPENDENT PREDICTOR OF TRANSPLANT-ASSOCIATED CORONARY ARTERY DISEASE AFTER CARDIAC TRANSPLANTATION1

BACKGROUND

Transplant-associated coronary artery disease (TxCAD) is the most serious long-term complication after cardiac transplantation. Anti-endothelial antibodies are associated with disease, and one of the major endothelial antigens recognized in the sera of patients has been shown to be the protein filament vimentin. In this study, we investigated whether antivimentin antibodies are associated with TxCAD and whether their presence can be used to identify patients at high risk of developing angiographically detectable TxCAD.

METHODS

Up to 5 years after transplantation, 880 sequential sera (7.07+/-1.8 samples/patient) were collected retrospectively from 109 patients; the majority were collected in the first 2 years. Sera were assessed for antivimentin antibodies using ELISA. TxCAD was assessed by annual angiography.

RESULTS

Mean titres of antivimentin antibodies, calculated up to 1, 2, and 5 years, were significantly higher in patients who developed TxCAD than those who remained disease free (P<0.0001, P<0.0038, and P<0.0001, respectively). A predictive test based on the first-year mean vimentin titre alone (> or = 120) produced a test with 63% sensitivity and 76% specificity. Inclusion of persistent rejection or high 1-year mean titre (> or = 270) as a risk factor produced a test with 66% sensitivity and 82% specificity. Multivariate analysis of time to occurrence of transplant vasculopathy showed that mean titre at 1 or 2 years was an independent predictor of time until disease in the presence of all other variables.

CONCLUSIONS

Antivimentin antibodies are an independent predictor of TxCAD and can be used to identify some of the patients who are at high risk of developing this complication.

Amyloplasts that sediment in protonemata of the moss Ceratodon purpureus are nonrandomly distributed in microgravity

Little is known about whether or how plant cells regulate the position of heavy organelles that sediment toward gravity. Dark-grown protonemata of the moss Ceratodon purpureus displays a complex plastid zonation in that only some amyloplasts sediment along the length of the tip cell. If gravity is the major force determining the position of amyloplasts that sediment, then these plastids should be randomly distributed in space. Instead, amyloplasts were clustered in the subapical region in microgravity. Cells rotated on a clinostat on earth had a roughly similar non-random plastid distribution. Subapical clusters were also found in ground controls that were inverted and kept stationary, but the distribution profile differed considerably due to amyloplast sedimentation. These findings indicate the existence of as yet unknown endogenous forces and mechanisms that influence amyloplast position and that are normally masked in stationary cells grown on earth. It is hypothesized that a microtubule-based mechanism normally compensates for g-induced drag while still allowing for regulated amyloplast sedimentation.

QS-21 synergizes with recombinant interleukin-12 to create a potent adjuvant formulation for the fusion protein of respiratory syncytial virus

In the murine model of respiratory syncytial virus (RSV) infection, recombinant interleukin-12 (rIL-12) was previously demonstrated to be most effective as an adjuvant for fusion (F) protein-based vaccines after adsorption to alum adjuvant. Alum, however, is a potent inducer of polarized T-cell responses and the type 2 phenotype. In addition, studies in human cancer patients demonstrated that rIL-12 was toxic when administered systemically at high doses. Because of these issues, we investigated whether the saponin QS-21 could facilitate a reduction in dose of rIL-12 when F protein was prepared in the absence of alum (F/rIL-12). The results demonstrated that a suboptimal dose (0.8 microg) of QS-21 enhanced the capacity of F/rIL-2 to elicit antigen-dependent killer cell precursors and complement-assisted neutralizing antibodies in spleens and sera respectively of BALB/c mice. The killer cell activity of mice vaccinated with F/rIL-12 (0.1 microg) plus 0.8 microg QS-21 was equivalent to that elicited after vaccination by experimental infection, or with an optimal dose of QS-21. The neutralizing titers generated by F/rIL-12 (0.01 to 1.0 microg) were also significantly elevated in the presence of 0.8 microg QS-21. Thus, rIL-12 and QS-21 together form a potent adjuvant for eliciting functional cell-mediated and humoral immune responses against F protein.

Effect of oral contraceptives on peripheral blood flow in untrained women at rest and during exercise

BACKGROUND

Endothelium-derived nitric oxide is an important mediator of exercise-induced changes in skeletal muscle blood flow. Given the recently documented effects of estrogens on nitric oxide synthase, it is hypothesized that oral contraceptives (OC) containing estrogen would increase nitric oxide production at rest and after endurance exercise. Further, we postulated that OC use would augment skeletal muscle blood flow at rest and during exercise.

METHODS

Fourteen women (non-smokers) were divided into two groups: control (CON; sedentary, normal menstrual-cycling women who have not used oral contraceptives for > or = 12 mons; 18-38 yrs old; n = 7), and oral contraceptive users (OC; sedentary women who have been using low-dose estrogen/progestin oral contraceptives for > or = 12 mons; 19-38 yrs old; n = 7). Measurements of forearm blood flow were obtained from each group, using strain gauge plethysmography, at rest and during an exercise protocol in which intermittent handgrip exercise was performed at 15%, 30%, and 45% of maximum voluntary contraction (MVC). Additionally, venous blood samples were taken before and after a 90 min treadmill walk for measurement of serum nitrate/nitrite, an indirect assessment of steady-state nitric oxide production.

RESULTS

There was no difference in forearm blood flow (ml/min/ 100 cc tissue) at rest (CON = 2.7; OC = 2.8); however, the hyperemic response to handgrip exercise was significantly (p < 0.05) lower in the OC group at 30% (9.0 vs CON = 14.2) and 45% (12.0 vs CON=17.0) of MVC. Serum nitrate values at rest and following 90 min of treadmill walking did not differ between groups (p > 0.05).

CONCLUSIONS

Contrary to our hypotheses, these data indicate a compromised hyperemic response in the forearm of OC users. Further, chronic OC use may not affect nitric oxide production during low intensity treadmill exercise.

Promoter polymorphisms of hepatic lipase gene influence HDL(2) but not HDL(3) in African American men: CARDIA study

Hepatic lipase encoded by the hepatic lipase gene (LIPC) is involved in the metabolism of several lipoproteins. Four promoter polymorphisms in LIPC have been found to be in complete disequilibrium and associated with high density lipoprotein cholesterol (HDL-C) and apolipoprotein (apo)A-I levels in both white and black populations. We investigated the association between the promoter polymorphism and lipid profiles as well as anthropometric phenotypes in African American men in the Coronary Artery Risk Development in Young Adults study. We performed serial cross-sectional analyses and longitudinal analyses of lipids from 578 subjects in five examinations over 10 years of follow-up. Results showed that the allele frequency (0.52) in our black population was consistent with that reported in black subjects but much higher than that reported (approximately 0.2) in white populations. Analysis of covariance tests of the three genotypic means in each examination showed that the P values ranged from 0.01 to 0.08 for HDL-C (except P = 0.54 in the fourth examination), from 0.006 to 0.01 for HDL(2)-C, and from 0.06 to 0.07 for apoA-I. Mean HDL(3)-C levels were essentially identical among the three genotypes. Total cholesterol, low density lipoprotein cholesterol (LDL-C), triglycerides, and apoB, which are mainly involved in the very low density lipoprotein-LDL pathway, were not significantly different according to the promoter polymorphism, except for triglycerides in the third examination (P = 0.01). No significant association was found between anthropometric phenotypes and the LIPC polymorphism in any of five examinations. The change of the anthropometric variables was not significantly associated with genotypes. In conclusion, our results indicated that the LIPC promoter polymorphism has exclusive effects on HDL(2)-C but not HDL(3)-C levels.

Endoglin, a TGF-beta receptor-associated protein, is expressed by smooth muscle cells in human atherosclerotic plaques

Endoglin is a transmembrane protein that is found in association with transforming growth factor-beta (TGF-beta) superfamily receptor complexes and has an expression pattern that appears to be restricted primarily to endothelial cells, activated macrophages, trophoblasts, and fibroblasts. Since mutations in endoglin have been shown to be linked to hereditary hemorrhagic telangiectasia type 1, a disease manifested as vascular malformations characterized by excessive layers of vascular smooth muscle cells (VSMC), the expression of endoglin was investigated in VSMC. In vivo, the majority of SMC in human atherosclerotic plaques expressed high levels of endoglin, while endoglin was not detected in SMC from samples of the normal arterial wall. In vitro studies demonstrate that human aortic smooth muscle cells (HASMC) express the L-isoform of endoglin. Like endothelial cells, HASMC express endoglin protein as a dimer on the cell surface that binds TGF-beta1. In vitro, endoglin expression by HASMC is upregulated in response to TGF-beta1, suggesting that the presence of this factor in the atherosclerotic plaque might be responsible for the increased expression of endoglin. The demonstration of increased levels of endoglin in VSMC in human atherosclerotic plaques suggests a role for SMC endoglin in the maintenance of vascular integrity and in the response of the vessel wall to injury.

Alcohol consumption raises HDL cholesterol levels by increasing the transport rate of apolipoproteins A-I and A-II

BACKGROUND

Moderate alcohol intake is associated with lower atherosclerosis risk, presumably due to increased HDL cholesterol (HDL-C) concentrations; however, the metabolic mechanisms of this increase are poorly understood.

METHODS AND RESULTS

We tested the hypothesis that ethanol increases HDL-C by raising transport rates (TRs) of the major HDL apolipoproteins apoA-I and -II. We measured the turnover of these apolipoproteins in vivo in paired studies with and without alcohol consumption in 14 subjects. The fractional catabolic rate (FCR) and TR of radiolabeled apoA-I and -II were determined in the last 2 weeks of a 4-week Western-type metabolic diet, without (control) or with alcohol in isocaloric exchange for carbohydrates. Alcohol was given as vodka in fixed amounts ranging from 0.20 to 0.81 g. kg(-1). d(-1) (mean+/-SD 0.45+/-0.19) to reflect the usual daily intake of each subject. HDL-C concentrations increased 18% with alcohol compared with the control (Wilcoxon matched-pairs test, P=0.002). The apoA-I concentrations increased by 10% (P=0.048) and apoA-II concentrations increased by 17% (P=0.005) due to higher apoA-I and -II TRs, respectively, whereas the FCR of both apoA-I and -II did not change. The amount of alcohol consumed correlated with the degree of increase in HDL-C (Pearson's r=0.66, P=0.01) and apoA-I TR (r=0.57, P=0.03). The increase in HDL-C also correlated with the increase in apoA-I TR (r=0.61, P=0.02).

CONCLUSIONS

Alcohol intake increases HDL-C in a dose-dependent fashion, associated with and possibly caused by an increase in the TR of HDL apolipoproteins apoA-I and -II.

Complications of foreign bodies in the esophagus

Major complications of foreign bodies in the esophagus carry significant morbidity and mortality risks. A retrospective case control study was performed to assess the factors associated with major complications. In total, 273 patients seen within a 7-year period were divided into 2 groups; 253 had no or minor complications, and 20 had major complications. Age, sex, duration of the foreign body, total white cell count (TWC), and nature and site of the foreign body were analyzed in the 2 groups. The major complication rate was 7.3%. Duration of the foreign body and TWC were the only statistically significant factors associated with major complications. Six patients required open neck exploration, 1 had an open thoracotomy, and 13 were treated by endoscopic removal. There were 2 deaths. Given the significant morbidity and mortality risks, we conclude that patients with a prolonged history of a foreign body in the esophagus and a raised TWC should be treated urgently.

Alleles of the estrogen receptor alpha-gene and an estrogen receptor cotranscriptional activator gene, amplified in breast cancer-1 (AIB1), are associated with quantitative calcaneal ultrasound

Quantitative bone ultrasound (QUS) has a significant heritable component. Because estrogen is required for attainment of peak bone mass, we studied alleles of two genes, estrogen receptor alpha (ER1) and amplified in breast cancer-1 (AIB1), for their association with QUS. In a volunteer sample of 663 white women aged 18-35 years, bone ultrasound attenuation (BUA), speed of sound (SOS), and heel stiffness index (SI), the latter consisting of the component measures of BUA and SOS, were measured at the right calcaneus by QUS. Subjects were genotyped for the ER1 polymorphisms Xba I and Pvu II and for the AIB1 polyglutamine tract polymorphism. In a multiple regression analysis, ER1 genotype was an independent predictor of QUS-SI (p = 0.03). Because AIB1 and ER1 enhance gene expression in a coordinate manner, we also searched for interactions. A gene-by-gene interaction effect was seen for QUS-SI (p = 0.009), QUS-BUA (p = 0.03), and QUS-SOS (p = 0.004). These remained significant after the inclusion of clinically relevant variables into the final regression model. Overall, these clinical and genetic factors accounted for up to 16% of the variance in peak QUS; the genetic markers alone accounted for 4-7%. This is the first demonstration of specific genetic effects on calcaneal QUS encoded by alleles of genes directly involved in mediating estrogen effects on bone.

Scavenger receptor-BI inhibits ATP-binding cassette transporter 1- mediated cholesterol efflux in macrophages

Scavenger receptor BI (SR-BI) facilitates the efflux of cellular cholesterol to plasma high density lipoprotein (HDL). Recently, the ATP-binding cassette transporter 1 (ABC1) was identified as a key mediator of cholesterol efflux to apolipoproteins and HDL. The goal of the present study was to determine a possible interaction between the SR-BI and ABC1 cholesterol efflux pathways in macrophages. Free cholesterol efflux to HDL was increased ( approximately 2.2-fold) in SR-BI transfected RAW macrophages in association with increased SR-BI protein levels. Treatment of macrophages with 8-bromo-cAMP (cAMP) resulted in a 4.1-fold increase in ABC1 mRNA level and also increased cholesterol efflux to HDL (2.2-fold) and apoA-I (5.5-fold). However, in SR-BI transfected RAW cells, cAMP treatment produced a much smaller increment in cholesterol efflux to HDL (1.1-fold) or apoA-I (3.3-fold) compared with control cells. In macrophages loaded with cholesterol by acetyl-LDL treatment, SR-BI overexpression did not increase cholesterol efflux to HDL but did inhibit cAMP-mediated cholesterol efflux to apoA-I or HDL. SR-BI neutralizing antibody led to a dose- and time-dependent increase of cAMP-mediated cholesterol efflux in both SR-BI transfected and control cells, indicating that SR-BI inhibits ABC1-mediated cholesterol efflux even at low SR-BI expression level. Transfection of a murine ABC1 cDNA into 293 cells led to a 2.3-fold increase of cholesterol efflux to apoA-I, whereas co-transfection of SR-BI with ABC1 blocked this increase in cholesterol efflux. SR-BI and ABC1 appear to have distinct and competing roles in mediating cholesterol flux between HDL and macrophages. In nonpolarized cells, SR-BI promotes the reuptake of cholesterol actively effluxed by ABC1, creating a futile cycle.

Classification of adhesive domains in the Plasmodium falciparum erythrocyte membrane protein 1 family

The Plasmodium falciparum Erythrocyte Membrane Protein 1 (PfEMP1) family of cytoadherent proteins has a central role in disease from malaria infection. This highly diverse gene family is involved in binding interactions between infected erythrocytes and host cells and is expressed in a clonally variant pattern at the erythrocyte surface. We describe by sequence analysis the structure and domain organization of 20 PfEMP1 from the GenBank database. Four domains comprise the majority of PfEMP1 extracellular sequence: the N-terminal segment (NTS) located at the amino terminus of all PfEMP1, the C2, the Cysteine-rich Interdomain Region (CIDR) and the Duffy Binding-like (DBL) domains. Previous work has shown that CIDR and DBL domains can possess adhesive properties. CIDR domains grouped as three distinct sequence classes (alpha, beta, and gamma) and DBL domains as five sequence classes (alpha, beta, gamma, delta, and epsilon). Consensus motifs are described for the different DBL and CIDR types. Whereas the number of DBL and CIDR domains vary between PfEMP1, PfEMP1 domain architecture is not random in that certain tandem domain associations--such as DBLalphaCIDRalpha, DBLdeltaCIDRbeta, and DBLbetaC2--are preferentially observed. This conservation may have functional significance for PfEMP1 folding, transport, or binding activity. Parasite binding phenotype appears to be a determinant of infected erythrocyte tissue tropism that contributes to parasite survival, transmission, and disease outcome. The sequence classification of DBL and CIDR types may have predictive value for identifying PfEMP1 domains with a particular binding property. This information might be used to develop interventions targeting parasite binding variants that cause disease.