A randomized trial of deferred stenting versus immediate stenting to prevent no- or slow-reflow in acute ST-segment elevation myocardial infarction (DEFER-STEMI)

OBJECTIVES

The aim of this study was to assess whether deferred stenting might reduce no-reflow and salvage myocardium in primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

No-reflow is associated with adverse outcomes in STEMI.

METHODS

This was a prospective, single-center, randomized, controlled, proof-of-concept trial in reperfused STEMI patients with ≥1 risk factors for no-reflow. Randomization was to deferred stenting with an intention-to-stent 4 to 16 h later or conventional treatment with immediate stenting. The primary outcome was the incidence of no-/slow-reflow (Thrombolysis In Myocardial Infarction ≤2). Cardiac magnetic resonance imaging was performed 2 days and 6 months after myocardial infarction. Myocardial salvage was the final infarct size indexed to the initial area at risk.

RESULTS

Of 411 STEMI patients (March 11, 2012 to November 21, 2012), 101 patients (mean age, 60 years; 69% male) were randomized (52 to the deferred stenting group, 49 to the immediate stenting). The median (interquartile range [IQR]) time to the second procedure in the deferred stenting group was 9 h (IQR: 6 to 12 h). Fewer patients in the deferred stenting group had no-/slow-reflow (14 [29%] vs. 3 [6%]; p = 0.006), no reflow (7 [14%] vs. 1 [2%]; p = 0.052) and intraprocedural thrombotic events (16 [33%] vs. 5 [10%]; p = 0.010). Thrombolysis In Myocardial Infarction coronary flow grades at the end of PCI were higher in the deferred stenting group (p = 0.018). Recurrent STEMI occurred in 2 patients in the deferred stenting group before the second procedure. Myocardial salvage index at 6 months was greater in the deferred stenting group (68 [IQR: 54% to 82%] vs. 56 [IQR: 31% to 72%]; p = 0.031].

CONCLUSIONS

In high-risk STEMI patients, deferred stenting in primary PCI reduced no-reflow and increased myocardial salvage. (Deferred Stent Trial in STEMI; NCT01717573).

The index of microcirculatory resistance measured acutely predicts the extent and severity of myocardial infarction in patients with ST-segment elevation myocardial infarction

OBJECTIVES

This study investigated the relationship between the index of microcirculatory resistance (IMR) with myocardial injury and microvascular obstruction (MVO) assessed by contrast-enhanced cardiac magnetic resonance (ceCMR) imaging in a broad range of ST-segment elevation myocardial infarction (STEMI) patients undergoing emergency percutaneous coronary intervention (PCI).

BACKGROUND

Contrast-enhanced cardiac magnetic resonance imaging is the gold standard for assessment of microvascular obstruction (MVO), left ventricular (LV) ejection fraction, and infarct volumes in ST-segment elevation myocardial infarction (STEMI). However, ceCMR is not available acutely. The index of microcirculatory resistance is a simple invasive measure of microvascular function available at the time of emergency PCI. We investigated the relationship between IMR with myocardial injury and MVO assessed by ceCMR in STEMI patients undergoing emergency PCI.

METHODS

Fifty-seven patients with STEMI were included and 53 (93%) and 47 (82%) patients had complete ceCMR scans 2 days and 3 months following MI, respectively. Microvascular obstruction was defined as a dark core of hypoenhancement within the area of hyperenhanced infarct tissue 10 to 15 min following intravenous gadolinium (0.1 mmol/kg).

RESULTS

The median IMR (interquartile range [IQR]) was 35 (24 to 63) U. Twenty-seven patients (46%) had MVO. We found that IMR (median [IQR]) was higher in patients with MVO (38 [29 to 55] U) than in patients without MVO (27 [18 to 36] U); p = 0.003). The index of microcirculatory resistance was a negative multivariable predictor of LV ejection fraction, (p < or = 0.001) and infarct volume (p = 0.01) on the ceCMR scan 2 days after MI, and IMR was a multivariable predictor of LV ejection fraction (p = 0.028) and infarct volume (p = 0.048) at 3 months.

CONCLUSIONS

The index of microcirculatory resistance measured acutely was higher in patients with MVO on ceCMR, and IMR independently predicted LV function and infarct volume. This easily measured physiological parameter provides important prognostic information at the time of emergency PCI.

PI3 Kinase Pathway Analysis in Tissue Microarrays Using Laser Capture Microdissection and Immunohistochemistry

Background. During the performance of the BCIRG trials primary patient tumor samples were obtained from paraffin blocks and assembled into 15 tissue microarrays, including 3000 samples from trial 005 (adjuvant taxol in Her2- node positive patients), 2200 in 006 (adjuvant herceptin in Her2+ high risk patients) and 300 in 007 (addition of platinum in Her2+ first line therapy). This array set was prepared prospectively, in anticipation of molecular epidemiologic studies of a variety of targets in relation to outcome. In order to address the potentially important role of the PIK3CA pathway in modulating outcome in different clinical situations we assessed components of the PIK3CA pathway by various methods.Methods. We analysed the expression of PTEN, Cyclin D1, p53 and Stathmin by immunohistochemistry using standard methods. All markers were scored by histoscore. Phospho S6 240 and phospho Akt 473 were assessed simultaneously by quantum dot immunofluorescence using automated image capture and segmentation. PIK3CA mutations were evaluated using SnaPshot analysis of laser captured TMA spots in a subset of approximately 2000 samples.Results. In the samples analyzed PIK3CA mutation had an incidence of 23%, with 9% being mutations in exon 9 and 13% in exon 20, with 0.5% being mutant in both exons. Initial analysis of the results prior to outcome analysis indicated that Stathmin expression, while being a robust marker with good dynamic range, did not appear to correlate with PTEN loss by IHC or with PIK3CA mutation.Conclusions. PIK3CA mutational analysis is feasible from TMA cores and gives mutation incidences similar to the published literature for archival material. Relationships of markers with outcome will be presented.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 4043.

Prognostic value of cardiovascular screening in potential renal transplant recipients: a single-center prospective observational study

We assessed the outcome of pretransplant cardiac assessment in a single center. Three hundred patients with end-stage renal disease underwent electrocardiogram, Bruce exercise testing (ETT) and ventricular assessment by cardiac MRI. Patients with high index of suspicion of coronary artery disease (CAD) underwent coronary angiography and percutaneous coronary intervention (PCI) if indicated. Two hundred and twenty-two patients were accepted onto the renal transplant waiting list; 80 patients were transplanted during the follow-up period and 60 died (7 following transplantation). Successful transplantation was associated with improved survival (mean survival 4.5 +/- 0.6 years vs. listed not transplanted 4.1 +/- 1.4 years vs. not listed 3.1 +/- 1.7 years; p < 0.001). Ninety-nine patients underwent coronary angiography; 65 had normal or low-grade CAD and 34 obstructive CAD. Seventeen patients (5.6%) were treated by PCI. There was no apparent survival difference between patients who underwent PCI or coronary artery bypass graft compared to those who underwent angiography without intervention or no angiography (p = 0.67). Factors associated with nonlisting for renal transplantation included burden of preexisting cardiovascular disease, poor exercise tolerance and severity of CAD. Pretransplant cardiovascular screening provides prognostic information and information that can be used to restrict access to transplantation. However, if the aim is to identify and treat CAD, the benefits are far from clear.

Prognostic value of cardiovascular screening in potential renal transplant recipients: a single-center prospective observational study

We assessed the outcome of pretransplant cardiac assessment in a single center. Three hundred patients with end-stage renal disease underwent electrocardiogram, Bruce exercise testing (ETT) and ventricular assessment by cardiac MRI. Patients with high index of suspicion of coronary artery disease (CAD) underwent coronary angiography and percutaneous coronary intervention (PCI) if indicated. Two hundred and twenty-two patients were accepted onto the renal transplant waiting list; 80 patients were transplanted during the follow-up period and 60 died (7 following transplantation). Successful transplantation was associated with improved survival (mean survival 4.5 +/- 0.6 years vs. listed not transplanted 4.1 +/- 1.4 years vs. not listed 3.1 +/- 1.7 years; p < 0.001). Ninety-nine patients underwent coronary angiography; 65 had normal or low-grade CAD and 34 obstructive CAD. Seventeen patients (5.6%) were treated by PCI. There was no apparent survival difference between patients who underwent PCI or coronary artery bypass graft compared to those who underwent angiography without intervention or no angiography (p = 0.67). Factors associated with nonlisting for renal transplantation included burden of preexisting cardiovascular disease, poor exercise tolerance and severity of CAD. Pretransplant cardiovascular screening provides prognostic information and information that can be used to restrict access to transplantation. However, if the aim is to identify and treat CAD, the benefits are far from clear.

Does pulmonary rehabilitation give additional benefit over tiotropium therapy in primary care management of chronic obstructive pulmonary disease? Randomized controlled clinical trial in Hong Kong Chinese

OBJECTIVE

To evaluate whether multidisciplinary pulmonary rehabilitation programme (PRP) provides additional benefit over tiotropium therapy in managing chronic obstructive pulmonary disease (COPD) in primary care.

DESIGN

A randomized controlled trial to analyse the difference in outcomes of COPD patients receiving tiotropium plus PRP vs. tiotropium treatment alone.

SETTING

Two primary care teaching clinics affiliated with a university which serves a population of 600,000.

PARTICIPANTS

Fifty primary care COPD patients.

METHODS

Fifty subjects underwent spirometry and their status of COPD was confirmed by using the Vitalograph Gold Standard. They were then assessed by the 6-min walking distance (6MWD), Peak Visual Analogue Scale (Peak VAS) and Chronic Respiratory Disease Questionnaire (CRQ). All subjects were given tiotropium to optimize their treatment. After a 6-week period, half were randomized to the intervention group (i.e. receiving PRP), whereas the rest were randomized to control group which received only medication. Spirometry, 6MWD, Peak VAS and CRQ were performed in both groups at 6 weeks, 12 weeks and 3 months.

OUTCOMES

Spirometry, 6MWD, Peak VAS and CRQ.

RESULTS

Significant improvement (P < 0.05) was seen in 6MWD, symptoms of dyspnoea measured by Peak VAS and CRQ. The improvement was sustained at 3-month follow-up. However, no additional significant improvement was seen in the intervention group when compared with control.

CONCLUSION

Tiotropium therapy has improved health outcomes in COPD patients in primary care settings. A 6 weekly PRP did not give any additional benefits in patients already given tiotropium.

Hysterectomy and ovarian function: levels of follicle stimulating hormone and incidence of menopausal symptoms are not affected by hysterectomy in women under age 45 years

OBJECTIVE

To investigate levels of follicle stimulating hormone (FSH), as a measure of ovarian function and menopausal symptoms prior to and following hysterectomy in women under the age of 45 years.

DESIGN

This was a prospective controlled study.

SAMPLE

A total of 56 hysterectomy patients and 34 controls, up to the age of 42 years, were recruited.

METHODS

Women undergoing hysterectomy were recruited prior to their operation and were matched, where possible, with controls for age, parity and smoking. Five blood samples were taken over 2 years, two before the operation (or at a 1-month interval in the control group) and then at 6 months, 1 year and 2 years. Questionnaires were completed at each sampling to assess symptoms associated with reduced estrogen secretion.

RESULTS

No significant differences in FSH levels between patients and controls were found. Modest differences in FSH levels between different time-points were identified (p = 0.03), but this disappeared if age and smoking were included as covariates. For the questionnaire data, there were no significant differences between the two groups on the somatic and vasomotor scales, but for psychological symptoms the patients scored significantly higher than the controls (p = 0.007), particularly at the pre-operation time-point.

CONCLUSION

The study found no evidence of compromise of ovarian function, as reflected in FSH levels, within 2 years of hysterectomy. Psychological symptoms were higher in women undergoing hysterectomy both before and after the operation.

Vaginal birth after cesarean among women with gestational diabetes

OBJECTIVE

We sought to determine the pregnancy and infant outcomes of women with gestational diabetes who attempted vaginal birth after previous cesarean delivery.

STUDY DESIGN

We conducted a retrospective cohort study to compare women with gestational diabetes with matched control subjects without diabetes who attempted vaginal birth after cesarean at Grady Memorial Hospital, Atlanta, from January 1, 1989, through December 31, 1999. One hundred fifty-six women with gestational diabetes were matched with 272 control subjects. Data were analyzed with the Student t test, chi2 analysis, and the Fisher exact test.

RESULTS

The parities of the women with gestational diabetes and the control subjects were similar, with most having had only one previous pregnancy. Women with gestational diabetes were significantly older than control subjects and more likely to be white or Hispanic. Women with gestational diabetes who attempted a trial of labor were significantly more likely than control subjects to be delivered abdominally. Women with gestational diabetes who had a successful vaginal birth after cesarean were significantly more likely than control subjects to have an operative delivery with forceps or vacuum.

CONCLUSION

Women with gestational diabetes are less likely than those without diabetes to have a successful trial of labor. Women with gestational diabetes considering vaginal birth after cesarean should be appropriately counseled about the risk of attempting a trial of labor after previous cesarean delivery.

Trends in operative vaginal delivery rates and associated maternal complication rates in an inner-city hospital

OBJECTIVE

The aims of this study were to determine trends in operative vaginal delivery rates in a large inner-city hospital and to assess associated risks.

STUDY DESIGN

We performed a retrospective cohort study (1980-1996) of women with singleton term pregnancies who underwent operative vaginal delivery at Grady Memorial Hospital, Atlanta. Maternal complication rates were compared between forceps-assisted and vacuum-assisted methods.

RESULTS

There was a decline in forceps-assisted deliveries during the 1980s and an increase during the 1990s. The vacuum-assisted delivery rate was exceedingly low during the 1980s and increased during the 1990s. Women who underwent forceps-assisted delivery were more likely to be <24 years old, to be nulliparous, and to have had regional anesthesia, midline episiotomies, and infant presentations other than occipitoanterior (P <.001). Women who underwent forceps-assisted deliveries had increased risks of postpartum infection, cervical laceration, prolonged hospital stay, perineal laceration, and postpartum complications.

CONCLUSION

There were upward trends in the rates of operative vaginal delivery at this inner-city hospital. Women who underwent forceps-assisted delivery had greater rates of maternal complications than did those who underwent vacuum-assisted delivery.

Postoperative morbidity associated with cesarean delivery among human immunodeficiency virus-seropositive women

OBJECTIVE

The aim of this study was to compare the complication rates associated with cesarean delivery between human immunodeficiency virus-seropositive women with those among a matched group of human immunodeficiency virus-seronegative subjects.

STUDY DESIGN

We conducted a case-control study of 86 human immunodeficiency virus-seropositive women undergoing cesarean delivery between the years 1992 and 2000 at a large, urban teaching institution and a control group of 86 human immunodeficiency virus-seronegative women matched for age, race, year of delivery, and delivery indications. Data were analyzed with the chi2 test and odds ratios. Among human immunodeficiency virus-seropositive women, complications were further stratified according to maternal disease status and use of antiretroviral therapy.

RESULTS

Human immunodeficiency virus-seropositive women were significantly more likely than control women to have minor postoperative complications (66.3% vs 41.8%; odds ratio, 2.73; 95% confidence interval, 1.40-6.10), of which febrile morbidity was the most common (62.8% vs 42.7%; P =.003). There was no difference between the groups in the rate of major complications (9.3% vs 3.4%; odds ratio, 2.84; 95% confidence interval, 0.65-14.06). Zidovudine use was associated with a decrease in the maternal morbidity rate (odds ratio, 0.31; 95% confidence interval, 0.07-1.03).

CONCLUSION

Postoperative morbidity among human immunodeficiency virus-seropositive women undergoing cesarean delivery was not different from that in a matched control population.

Mobilization of MHC class I molecules from late endosomes to the cell surface following activation of CD34-derived human Langerhans cells

Langerhans cells are a subset of dendritic cells (DCs) found in the human epidermis with unique morphological and molecular properties that enable their function as "sentinels" of the immune system. DCs are pivotal in the initiation and regulation of primary MHC class I restricted T lymphocyte immune responses and are able to present both endogenous and exogenous antigen onto class I molecules. Here, we study the MHC class I presentation pathway following activation of immature, CD34-derived human Langerhans cells by lipopolysaccharide (LPS). LPS induces an increase in all components of the MHC class I pathway including the transporter for antigen presentation (TAP), tapasin and ERp57, and the immunoproteasome subunits LMP2 and LMP7. Moreover, in CD34-derived Langerhans cells, the rapid increase in expression of MHC class I molecules seen at the cell surface following LPS activation is because of mobilization of MHC class I molecules from HLA-DM positive endosomal compartments, a pathway not seen in monocyte-derived DCs. Mobilization of class I from this compartment is primaquine sensitive and brefeldin A insensitive. These data demonstrate the regulation of the class I pathway in concert with the maturation of the CD34-derived Langerhans cells and suggest potential sites for antigen loading of class I proteins.

Localization of phosphatidylinositol 3-phosphate in yeast and mammalian cells

Phosphatidylinositol 3-kinase (PI3K) regulates several vital cellular processes, including signal transduction and membrane trafficking. In order to study the intracellular localization of the PI3K product, phosphatidylinositol 3-phosphate [PI(3)P], we constructed a probe consisting of two PI(3)P-binding FYVE domains. The probe was found to bind specifically, and with high affinity, to PI(3)P both in vitro and in vivo. When expressed in fibroblasts, a tagged probe localized to endosomes, as detected by fluorescence microscopy. Electron microscopy of untransfected fibroblasts showed that PI(3)P is highly enriched on early endosomes and in the internal vesicles of multivesicular endosomes. While yeast cells deficient in PI3K activity (vps15 and vps34 mutants) were not labelled, PI(3)P was found on intralumenal vesicles of endosomes and vacuoles of wild-type yeast. vps27Delta yeast cells, which have impaired endosome to vacuole trafficking, showed a decreased vacuolar labelling and increased endosome labelling. Thus PI(3)P follows a conserved intralumenal degradation pathway, and its generation, accessibility and turnover are likely to play a crucial role in defining the early endosome and the subsequent steps leading to multivesicular endosome formation.

Syntaxin 7 is localized to late endosome compartments, associates with Vamp 8, and Is required for late endosome-lysosome fusion

Protein traffic from the cell surface or the trans-Golgi network reaches the lysosome via a series of endosomal compartments. One of the last steps in the endocytic pathway is the fusion of late endosomes with lysosomes. This process has been reconstituted in vitro and has been shown to require NSF, alpha and gamma SNAP, and a Rab GTPase based on inhibition by Rab GDI. In Saccharomyces cerevisiae, fusion events to the lysosome-like vacuole are mediated by the syntaxin protein Vam3p, which is localized to the vacuolar membrane. In an effort to identify the molecular machinery that controls fusion events to the lysosome, we searched for mammalian homologues of Vam3p. One such candidate is syntaxin 7. Here we show that syntaxin 7 is concentrated in late endosomes and lysosomes. Coimmunoprecipitation experiments show that syntaxin 7 is associated with the endosomal v-SNARE Vamp 8, which partially colocalizes with syntaxin 7. Importantly, we show that syntaxin 7 is specifically required for the fusion of late endosomes with lysosomes in vitro, resulting in a hybrid organelle. Together, these data identify a SNARE complex that functions in the late endocytic system of animal cells.

The tetraspanin CD63/lamp3 cycles between endocytic and secretory compartments in human endothelial cells

In the present study, we show that in human endothelial cells the tetraspanin CD63/lamp3 distributes predominantly to the internal membranes of multivesicular-multilamellar late endosomes, which contain the unique lipid lysobisphosphatidic acid. Some CD63/lamp3 is also present in Weibel-Palade bodies, the characteristic secretory organelle of these cells. We find that CD63/lamp3 molecules can be transported from late endosomes to Weibel-Palade bodies and thus that CD63/lamp3 cycles between endocytic and biosynthetic compartments; however, movement of CD63/lamp3 is much slower than that of P-selectin, which is known to cycle between plasma membrane and Weibel-Palade bodies. When cells are treated with U18666A, a drug that mimics the Niemann-Pick type C syndrome, both proteins accumulate in late endosomes and fail to reach Weibel-Palade bodies efficiently, suggesting that P-selectin, like CD63/lamp3, cycles via late endosomes. Our data suggest that CD63/lamp3 partitions preferentially within late endosome internal membranes, thus causing its accumulation, and that this mechanism contributes to CD63/lamp3 retention in late endosomes; however, our data also indicate that the protein can eventually escape from these internal membranes and recycle toward Weibel-Palade bodies to be reused. Our observations thus uncover the existence of a selective trafficking route from late endosomes to Weibel-Palade bodies.

H-ras but not K-ras traffics to the plasma membrane through the exocytic pathway

Ras proteins must be localized to the inner surface of the plasma membrane to be biologically active. The motifs that effect Ras plasma membrane targeting consist of a C-terminal CAAX motif plus a second signal comprising palmitoylation of adjacent cysteine residues or the presence of a polybasic domain. In this study, we examined how Ras proteins access the cell surface after processing of the CAAX motif is completed in the endoplasmic reticulum (ER). We show that palmitoylated CAAX proteins, in addition to being localized at the plasma membrane, are found throughout the exocytic pathway and accumulate in the Golgi region when cells are incubated at 15 degrees C. In contrast, polybasic CAAX proteins are found only at the cell surface and not in the exocytic pathway. CAAX proteins which lack a second signal for plasma membrane targeting accumulate in the ER and Golgi. Brefeldin A (BFA) significantly inhibits the plasma membrane accumulation of newly synthesized, palmitoylated CAAX proteins without inhibiting their palmitoylation. BFA has no effect on the trafficking of polybasic CAAX proteins. We conclude that H-ras and K-ras traffic to the cell surface through different routes and that the polybasic domain is a sorting signal diverting K-Ras out of the classical exocytic pathway proximal to the Golgi. Farnesylated Ras proteins that lack a polybasic domain reach the Golgi but require palmitoylation in order to traffic further to the cell surface. These data also indicate that a Ras palmitoyltransferase is present in an early compartment of the exocytic pathway.

Interaction of anti-phospholipid antibodies with late endosomes of human endothelial cells

Anti-phospholipid antibodies (APLAs) are associated with thrombosis and/or recurrent pregnancy loss. APLAs bind to anionic phospholipids directly or indirectly via a cofactor such as beta(2)-glycoprotein 1 (beta(2)GPI). The lipid target of APLA is not yet established. Recently, we observed that APLAs in vitro can bind lysobisphosphatidic acid (LBPA). The internal membranes of late endosomes are enriched in this phospholipid. The current study was undertaken to determine to what extent binding of APLA to LBPA is correlated with binding to cardiolipin and to beta(2)GPI and to determine whether patient antibodies interact with late endosomes of human umbilical vein endothelial cells (HUVECs) and thus modify the intracellular trafficking of proteins. Binding of patient immunoglobulin G (n=37) to LBPA was correlated significantly with binding to cardiolipin. Although LBPA binding was correlated to a lesser extent with beta(2)GPI binding, we observed that beta(2)GPI binds with high affinity to LBPA. Immunofluorescence studies showed that late endosomes of HUVECs contain LBPA. Patient but not control antibodies recognized late endosomes, but not cardiolipin-rich mitochondria, even when we used antibodies that were immunopurified on cardiolipin. Incubation of HUVECs with patient plasma samples immunoreactive toward LBPA resulted in an accumulation of the antibodies in late endosomes and led to a redistribution of the insulinlike growth factor 2/mannose-6-phosphate receptor from the Golgi apparatus to late endosomes. Our results suggest that LBPA is an important lipid target of APLA in HUVECs. These antibodies are internalized by the cells and accumulate in late endosomes. By modifying the intracellular trafficking of proteins, APLA could contribute to several of the proposed pathogenic mechanisms leading to the antiphospholipid syndrome.

Cerebral vascular accident after cardiac surgery: its impact on nursing care

The number of patients undergoing coronary artery bypass grafting (CABG) per year is increasing. Despite advances in surgical techniques, cerebral vascular accident (CVA) post cardiac surgery is increasing. CVA is a severe neurological complication of cardiac surgery which increased length of stay, morbidity and mortality, and rehabilitation. It is important to identify patients at increased risk and utilize appropriate screening techniques to decrease the incidence of CVA. Nursing assessment, interventions, and postoperative neurological assessment is crucial in identifying patients at increased risk for CVA.

Late endosomal membranes rich in lysobisphosphatidic acid regulate cholesterol transport

The fate of free cholesterol released after endocytosis of low-density lipoproteins remains obscure. Here we report that late endosomes have a pivotal role in intracellular cholesterol transport. We find that in the genetic disease Niemann-Pick type C (NPC), and in drug-treated cells that mimic NPC, cholesterol accumulates in late endosomes and sorting of the lysosomal enzyme receptor is impaired. Our results show that the characteristic network of lysobisphosphatidic acid-rich membranes contained within multivesicular late endosomes regulates cholesterol transport, presumably by acting as a collection and distribution device. The results also suggest that similar endosomal defects accompany the anti-phospholipid syndrome and NPC.

Exploitation of major histocompatibility complex class I molecules and caveolae by simian virus 40

Simian virus 40 (SV40), a non-enveloped DNA virus, is transported from the cell surface to the nucleus where virus replication occurs. This pathway of virus uptake involves binding to surface MHC class I molecules, entry via non-coated pits, and subsequent transport to the endoplasmic reticulum (ER). At some stage in this pathway the virus must cross a membrane to reach the cytosol. In the present review, the cellular machinery which the virus has utilized to enter the cell will be examined. In particular, we will consider recent evidence for the involvement of caveolae in the infectious entry step and propose a model involving recruitment of caveolar proteins around the membrane-bound virus. We also speculate that a similar mechanism may have been exploited by bacterial pathogens. The subsequent steps by which SV40 reaches the ER remain unclear but recent evidence suggests that this pathway may be shared with several other proteins that are transported from surface caveolae to the ER.