A continuum-based outcome approach to measuring performance in HIV/AIDS case management

This methods paper is third in a series addressing client outcomes in HIV/AIDS case management. After introducing earlier work the authors outline their effort to consolidate numerous discrete outcome measures and to establish each outcome indicator along a continuum scale that can be self-abstracted by HIV/AIDS service providers. The paper includes in-depth discussion of challenges and benefits derived from this type of outcome measurement process. Key lessons learned from a pilot study are offered for those considering development of similar client outcomes assessment programmes. The paper concludes with several opportunities for future research for those desiring to work in this relatively uncharted domain.

Higher thrombin concentrations are required to induce platelet apoptosis than to induce platelet activation

Primarily known as an inducer of blood coagulation and platelet activation, thrombin also triggers platelet apoptosis. This study demonstrated that the platelet activation response is much more sensitive than platelet apoptosis to thrombin treatment. Thrombin concentrations of 0.5-1 nmol/l activated almost all platelets, but only a small fraction underwent apoptosis, suggesting that at these relatively low thrombin concentrations, platelets may perform haemostasis but not be involved in programmed cell death. At high thrombin concentrations of 10-100 nmol/l, generated during blood coagulation, 30-40% of platelets became apoptotic, indicating that hypercoagulable states may be associated with increased numbers of apoptotic platelets.

Persistence of procoagulant surface expression on activated human platelets: involvement of apoptosis and aminophospholipid translocase activity

BACKGROUND

Activated platelets express a procoagulant surface when the asymmetric distribution of membrane phospholipids is scrambled, leading to phosphatidylserine (PS) exposure. PS expression, associated with apoptosis in nucleated cells, would be expected to be reversed by aminophospholipid translocase (APLT) activity.

OBJECTIVE

To determine whether the procoagulant surface of activated platelets persists after it forms; to examine whether PS expression on platelets is associated with loss of mitochondrial inner membrane potential (DeltaPsi(m)), a hallmark of apoptosis; and to investigate the role of APLT in persistence of PS expression.

METHODS

Platelets were stimulated with thrombin, collagen, a combination of both, or the Ca(2+)-ionophore A23187. Up to 4 h after activation, procoagulant surface expression was measured by annexin A5 binding by flow cytometry and by a prothrombinase assay. Flow cytometry was also used to measure PS expression concurrently with DeltaPsi(m) collapse, using CMXRos. APLT activity in annexin A5-negative and -positive platelets was measured flow cytometrically as the percent of 1-palmitoyl-2-[6-[(7-nitro-2-1,3-benzoxadiazol-4-yl)amino]caproyl]-sn-glycero-3-phosphatidylserine (NBD-PS) translocated from the outer to the inner membrane leaflet.

RESULTS AND CONCLUSIONS

Procoagulant surface expression on activated platelets persisted in vitro for at least 4 h; if such persistence occurs in vivo, there are important implications for the propagation of thrombosis. With the physiological stimuli, only 10-20% of the activated platelets expressed PS on their surface, and of these, only a portion exhibited DeltaPsi(m) collapse, indicating that PS expression can be associated with platelet apoptosis, but can also occur independently. APLT activity was very low in the PS-expressing platelet subpopulation for up to 4 h after activation, indicating that the persistence of a procoagulant surface may be attributed, at least in part, to this reduced APLT activity.

Thrombin-triggered platelet apoptosis

BACKGROUND

Thrombin is primarily known as a coagulation factor and as an inducer of platelet activation and aggregation. It has been reported that thrombin modulates apoptosis of nucleated cells.

OBJECTIVES

The current study investigated whether thrombin can affect apoptosis in anucleated human platelets.

METHODS

Using flow cytometry, we studied platelet apoptosis at the single-cell level, analyzing markers of mitochondrial and cytoplasmic apoptosis. Western blotting was also employed, in addition to flow cytometry, for determining the expression of Bcl-2 family proteins.

RESULTS

We found that human alpha-thrombin induced four key manifestations of apoptosis in human platelets: (i) mitochondrial inner transmembrane potential (DeltaPsi m) depolarization; (ii) strong expression of pro-apoptotic Bax and Bak proteins but only weak expression of anti-apoptotic Bcl-2 protein; (iii) caspase-3 activation; and (iv) phosphatidylserine (PS) exposure.

CONCLUSIONS

This study demonstrates that, aside from its 'classical' function as an inducer of platelet activation, thrombin can trigger platelet apoptosis, where it acts as a death ligand. These data indicate that thrombin triggers platelet apoptosis by impacting on several intracellular apoptotic targets, including shifting the balance between Bcl-2 regulatory proteins in a pro-apoptotic direction, depolarizing the inner mitochondrial membrane, activating the executioner caspase-3, and stimulating aberrant exposure of PS on the platelet surface.

Fibrinogen and von Willebrand factor-independent platelet aggregation in vitro and in vivo

BACKGROUND

Fibrinogen (Fg) has been considered essential for platelet aggregation. However, we recently demonstrated formation of occlusive thrombi in Fg-deficient mice and in mice doubly deficient for Fg and von Willebrand factor (Fg/VWF(-/-)).

METHODS AND RESULTS

Here we studied Fg/VWF-independent platelet aggregation in vitro and found no aggregation in citrated platelet-rich plasma of Fg/VWF(-/-) mice. Surprisingly, in Fg/VWF(-/-) plasma without anticoagulant, adenosine diphosphate induced robust aggregation of Fg/VWF(-/-) platelets but not of beta(3)-integrin-deficient (beta(3) (-/-)) platelets. In addition, beta(3) (-/-) platelets did not significantly incorporate into thrombi in Fg/VWF(-/-) mice. This Fg/VWF-independent aggregation was blocked by thrombin inhibitors (heparin, hirudin, PPACK), and thrombin or thrombin receptor activation peptide (AYPGKF-NH(2)) induced aggregation of gel-filtered Fg/VWF(-/-) platelets in 1 mm Ca(2+) PIPES buffer. Notably, aggregation in PIPES buffer was only 50-60% of that observed in Fg/VWF(-/-) plasma. Consistent with the requirement for thrombin in vitro, hirudin completely inhibited thrombus formation in Fg/VWF(-/-) mice. These data define a novel pathway of platelet aggregation independent of both Fg and VWF. Although this pathway was not detected in the presence of anticoagulants, it was observed under physiological conditions in vivo and in the presence of Ca(2+)in vitro.

CONCLUSIONS

beta(3) integrin, thrombin, and Ca(2+) play critical roles in this Fg/VWF-independent aggregation, and both plasma and platelet granule proteins contribute to this process.

A provincial program of blood conservation: The Ontario Transfusion Coordinators (ONTraC)

PURPOSE

Although often life-saving, blood transfusions are associated with significant risk to the patient and escalating costs to the blood system and hospital. Transfusions are often given unnecessarily. Blood conservation represents the use of alternatives to transfusion. The ONTraC program attempts to enhance transfusion practice outside the blood transfusion laboratory, promote blood conservation in surgery patients, and reduce allogeneic red cell use.

METHODS

In the first such large scale program, funding was obtained from the Ontario MOHLTC for a Transfusion Coordinator in 23 Ontario hospitals selected based on blood utilization and geography. At specific time periods, detailed anonymized information was collected in a defined number of all consecutive patients admitted for the three designated surgical procedures: knee arthroplasty (N=approximately 1200 at each time point), abdominal aortic aneurysm (AAA; N=300 at each time) and coronary artery bypass graft (CABG) surgery (N=300 at each time point).

RESULTS

Considerable inter-institutional variation was observed in the proportion of patients and amount of blood transfused. At the 12 month analysis, most, although not all, hospitals had decreased use of allogeneic blood and there was an overall 24% reduction in blood use in patients undergoing knee surgery, 14% in AAA and 23% in CABG. In addition to reduction in proportion of patients transfused, transfused patients received fewer units of allogeneic blood. Patients who did not receive allogeneic transfusions had significantly lower postoperative infection rates (p<0.05) and length of stay (p<0.0001); multivariate analysis showed that allogeneic transfusion was an independent predictor of increased length of stay. Eighteen-month analysis indicates even greater reduction in allogeneic transfusion. The main measures of blood conservation employed were preoperative autologous donation and education, with recent increasing use of erythropoietin and the cell saver. These measures have been demonstrated to be very effective in avoiding allogeneic transfusion.

CONCLUSIONS

The ONTraC have become leaders locally, nationally and internationally in blood conservation. The reduction in allogeneic transfusion associated with the implementation of the ONTraC program represents important savings in costs associated with blood components, hospital stay and work in transfusion laboratories and nursing units, as well as enhancing patient satisfaction and safety.

Vitronectin stabilizes thrombi and vessel occlusion but plays a dual role in platelet aggregation

The role of vitronectin (Vn) in thrombosis is currently controversial; both inhibitory and supportive roles have been reported. To monitor directly the function of Vn in thrombotic events at the site of vascular injury, we studied Vn-deficient (Vn-/-) and wild-type (WT) control mice with two real-time intravital microscopy thrombosis models. In the mesenteric arteriole model, vessel injury was induced by ferric chloride. We observed unstable thrombi and a significantly greater number of emboli in Vn-/- mice. Vessel occlusion was also delayed and frequent vessel re-opening occurred. In the cremaster muscle arteriole model, vessel injury was induced by a nitrogen dye laser. We observed significantly fewer platelets, lower fibrin content, and unstable fibrin within the thrombi of Vn-/- mice. To define further the role of Vn in thrombus growth, we studied platelet aggregation in vitro. Consistent with our in vivo data, the second wave of thrombin-induced aggregation of gel-filtered platelets was abolished at a low concentration of thrombin in Vn-/- platelets. Interestingly, adenosine diphosphate (ADP)-induced platelet aggregation was significantly increased in Vn-/- platelet-rich plasma (PRP) and this effect was attenuated by adding purified plasma Vn. We also observed increased platelet aggregation induced by shear stress in Vn-/- whole blood. These data demonstrate that Vn is a thrombus stabilizer. However, in contrast to released platelet granule Vn which enhances platelet aggregation, plasma Vn inhibits platelet aggregation.

Triple heterozygosity in the integrin alphaIIb subunit in a patient with Glanzmann's thrombasthenia

We report triple heterozygosity in the integrin alpha(IIb) subunit in a 5-year-old Canadian girl with Glanzmann's thrombasthenia. The patient has a severe bleeding history possibly aggravated by low VWF suggestive of associated type 1 von Willebrand's disease. Platelet aggregation was absent or severely reduced for all physiologic agonists. Flow cytometry showed an approximately 4% residual surface expression of alpha(IIb)beta(3). Western blotting confirmed a low platelet expression of both subunits. PCR-SSCP and direct sequencing showed no abnormalities in the beta(3) gene, but revealed a G-->A transition at a splice site [IVS 19 (+1)] of exon 19 in the alpha(IIb) gene. Of maternal inheritance, the splice site mutation was associated with intermediate levels of alpha(IIb)beta(3) in carriers. Unexpectedly, two G-->A transitions were detected in exon 29 of the alpha(IIb) gene and led to V(951)-->M and A(958)-->T amino acid substitutions. Family studies using restriction enzymes showed that both exon 29 mutations were paternal in origin and cosegregated across three generations. Transient expression in which mutated alpha(IIb) was cotransfected with wild-type beta(3) in COS-7 cells showed that V(951)-->M gave a much reduced surface expression of alpha(IIb)beta(3) and a block in the maturation of pro-alpha(IIb). In contrast, the A(958) substitution appeared to be a novel polymorphism. Our studies highlight an unusual mixture of defects giving rise to severe bleeding in a child and describe the first pathological missense mutation affecting a C-terminal residue of the calf-2 domain of alpha(IIb).

Procoagulant surface exposure and apoptosis in rabbit platelets: association with shortened survival and steady-state senescence

BACKGROUND

The signal(s) for removal of senescent platelets from the circulation are not fully understood; phosphatidylserine (PS) expression on platelets and another marker of apoptosis, loss of mitochondrial inner membrane potential (DeltaPsim), have been implicated in platelet clearance.

OBJECTIVE

To investigate whether shortened platelet survival and steady-state platelet senescence are associated with increased surface exposure of PS and DeltaPsim collapse.

METHODS

Survival of in-vitro biotinylated rabbit platelets treated with thrombin or Ca(2+)-ionophore A23187 was tracked by flow cytometry after injection. Steady-state platelet senescence was investigated by infusing biotin to label a platelet cohort. PS expression and DeltaPsim of in-vitro biotinylated platelets and of the aging platelet cohort biotinylated in-vivo were measured by flow cytometry using annexin V-FLUOS and the DeltaPsim-sensitive dye CMXRos, respectively.

RESULTS

Although PS expression, DeltaPsim and survival of thrombin-degranulated platelets were similar to those of control platelets, increasing concentrations of A23187 caused increased surface exposure of PS and progressive shortening of platelet survival; only one-sixth of PS-expressing platelets also exhibited DeltaPsim loss. The cohort of senescent, biotinylated platelets remaining in the circulation at 96 h had increased exposure of PS and collapsed DeltaPsim; of the 17% of PS-expressing platelets, one-third did not exhibit DeltaPsim loss. There was also an increase in platelets with collapsed DeltaPsim but not expressing PS.

CONCLUSIONS

Platelets with shortened survival and senescent platelets have increased surface exposure of PS, that may be involved in their clearance. PS expression can occur independently of DeltaPsim collapse and conversely, in aged platelets, DeltaPsim loss can occur independently of PS expression.

The activity of the von Willebrand factor cleaving protease ADAMTS-13 in newborn infants

BACKGROUND

Unusually large von Willebrand factor (VWF) multimers have been observed in patients with thrombotic microangiopathies (TMA), and absence of the VWF cleaving protease ADAMTS-13 activity is considered to be involved in the etiology of TMA. Increased amounts of large multimers of VWF have also been identified in neonates.

OBJECTIVE

We assessed ADAMTS-13 activity in healthy neonates, children and adults to establish baseline levels.

PATIENTS AND METHODS

Cord blood was collected from 38 full-term newborns; venous samples were taken from 15 neonates on day 2-3 of life. Seventeen children, 24 healthy adults and seven patients with TMA were studied as well. ADAMTS-13 activity was quantified by the binding of the subjects' plasma VWF to collagen before and after enzyme activation. The multimer distribution of VWF was also determined.

RESULTS

Neonates and children had percentage ADAMTS-13 activity similar to adults. However, two groups were apparent in the cord blood samples: while 28/38 newborns had percentage activity within the normal range of healthy adults (102 +/- 3.0%), 10 had significantly lower percentage activity (53 +/- 1.1%; P < 0.0001) that normalized by day 2-3. The VWF multimer distribution was the same in all cord blood samples and was not different compared with children and adults. High-molecular-weight VWF multimers were significantly increased in the 2-3-day-old neonates and in TMA patients.

CONCLUSIONS

Although ADAMTS-13 activity was similar in neonates compared with adults, 26% of neonates had mildly reduced activity. Further studies are needed to investigate the complex interaction of VWF production and secretion with its size control by ADAMTS-13 in different age groups.

von Willebrand factor (VWF)-dependent human platelet activation: porcine VWF utilizes different transmembrane signaling pathways than does thrombin to activate platelets, but both require protein phosphatase function

The interaction between von Willebrand factor (VWF) and glycoprotein (GP) Ib results in platelet agglutination and activation of many signaling intermediates. To determine if VWF-dependent platelet activation requires the participation of pivotal transmembrane signaling pathways, we analyzed VWF-dependent platelet activation profiles following inhibition of several transmembrane signaling intermediates. This was accomplished using porcine VWF, which has been shown to interact with human GPIb independently of shear stress or ristocetin. Platelet alpha (CD62) and lysozomal granule release (CD63), microparticle formation, and platelet agglutination/aggregation were evaluated. The ability of signaling inhibitors to prevent VWF-dependent platelet activation was compared to their ability to inhibit thrombin-dependent activation. The results demonstrate that VWF-dependent platelet activation can occur independently of the activities of protein kinase C (PKC), wortmannin-sensitive phosphatidylinositide 3-kinase, and phospholipase C, as well as independently of elevations in the concentration of intracellular calcium. In sharp contrast, these transmembrane signaling intermediates are required for thrombin-dependent platelet activation. In addition, thrombin-dependent but not VWF-dependent platelet activation was associated with elevations in the concentration of intracellular calcium under the conditions used. The family of signaling intermediates which appeared to be pivotal for both thrombin- and VWF-dependent platelet activation were the protein tyrosine phosphatases and the serine/threonine phosphatases. It is concluded that thrombin-dependent platelet activation relies on the activation of several transmembrane signaling pathways, whereas VWF-dependent platelet activation is dependent upon the activity of protein phosphatases. Inhibition of these phosphatases in vivo may provide a novel therapeutic approach for treating VWF-dependent platelet disorders such as thrombotic thrombocytopenic purpura or arterial thrombosis.

Development and implementation of an HIV/AIDS case management outcomes assessment programme

The Case Management Section of the New York State Department of Health AIDS Institute coordinates the provision of case management services for people living with HIV/AIDS throughout the state. The Community Follow-Up Program (CFP), providing intensive case management for HIV-positive individuals and their families, operates under the auspices of the Case Management Section. This article focuses on a public/private outcomes assessment partnership, sponsored by the Case Management Section, and developed in conjunction with a team of CFP programme managers from across the state. The process used to develop outcome indicators and measures is described; challenges encountered along the way are detailed; and suggestions for other public/private partnerships are outlined. Results from two years of outcomes data collection are also presented. The article concludes that the inclusion of providers in the identification and measurement of desired outcomes can help overcome provider resistance to outcomes assessment and can help ensure that outcomes data are used to improve programme performance.

Gastric emptying and duodeno-gastro-oesophageal reflux in gastro-oesophageal reflux disease

BACKGROUND

Previous studies present conflicting results regarding relationship between gastric emptying and gastro-oesophageal reflux disease. Reflux of duodenal content to oesophagus is generally considered to be associated with more severe disease.

AIM

To assess presence of a gastric emptying disorder in persons with reflux of duodenal contents to oesophagus and to identify any correlation with gastric emptying and oesophageal motility.

METHODOLOGY

A total of 15 subjects with (B+) and 15 subjects without (B-) bile reflux to oesophagus determined by 24-hour bilirubin monitoring were studied with scintigraphic solid gastric emptying and 24-hour oesophageal manometry.

RESULTS

There was no difference in lag phase [median 23.7 (range 10.8-44.0) vs 24.6 (8.1-40.1) min], half emptying time [74.6 (48.0-93.6) vs 82.8 (54.4-153.9) min] or emptying rate [0.89 (0.59-1.34) vs 0.83 (0.36-1. 15)%/min] for B- and B+ subjects, respectively. In addition, there was no difference in emptying rate of gastric fundus between B- and B+ subjects. Subjects with bile reflux had less effective oesophageal contractions of oesophageal body [9.4(3.3-37)%] compared to subjects without bile reflux [32(19-47)%, p = 0.002]. However, there was no correlation between oesophageal motility and gastric emptying.

CONCLUSION

Results suggest that a gastric emptying disorder is a less likely contributing cause of bile reflux to the oesophagus, but bile reflux is associated with less effective oesophageal motility.

Anti-D (WinRho SD) treatment of children with chronic autoimmune thrombocytopenic purpura stimulates transient cytokine/chemokine production

Intravenous anti-D is often used in the treatment of autoimmune thrombocytopenic purpura (AITP), but little is known about its mechanisms of action. To investigate anti-D's potential in vivo mechanism(s) of action, a small group (N = 7) of children with chronic AITP was studied. The children initially received either 25 or 50 microg/kg of WinRho-SD in a four-cycle cross-over trial, and peripheral blood samples from the first and third cycles were assessed for cytokine levels at pre-treatment, 3 hr, 1 day, and 8 days post-treatment. Results showed that platelet counts significantly increased in all the children by day 8 post-treatment. Analysis of serum by ELISA showed that there was a significant but transient rise in both pro- and anti-inflammatory cytokine/chemokine levels (e.g., IL1RA, IL6, GM-CSF, MCP-1 alpha, TNF-alpha and MCP-1) by 3 hr post-treatment in both cycles which returned to baseline levels by 8 days post-treatment. These results suggest that anti-D administration may initially activate the RES in the form of cytokine/chemokine secretion, which is subsequently followed by an increase in platelet counts. It is possible that the induced cytokine/chemokine storm may have an effect on several physiological processes such as those mediating either adverse effects or potentially RES phagocytic activity.

Platelet activation and hypercoagulability following treatment with porcine factor VIII (HYATE:C)

Activation of platelets and coagulation in vivo was studied in nine patients with hemophilia A and inhibitors to human Factor VIII, prior to and following treatment with porcine Factor VIII (PFVIII; HYATE:C). In addition, six hemophiliac patients were similarly studied after treatment with recombinant Factor VIII (rFVIII). Platelet activation was also examined in vitro using porcine von Willebrand factor (PvWF)-enriched and PvWF-depleted fractions obtained by fractionation of PFVIII. Coagulation was assessed by measuring the concentrations of plasma prothrombin fragment 1+2 concentrations (prothrombinase generation) and Factor Xa-ATIII. Patients treated with PFVIII had significantly increased numbers of circulating platelets expressing CD62 and CD63 (markers of platelet activation) and annexin V (marker of platelet procoagulant activity) compared to patients treated with rFVIII; the former patients also demonstrated an increase in plasma coagulability after therapy. In in vitro experiments it was observed that the platelet-activating and procoagulant capacity of PFVIII resided in the PvWF-enriched fraction, and the same was true for the plasma hypercoagulability following exposure of platelets to PFVIII. These results support the hypothesis that PFVIII-induced platelet activation provides a mechanism for enhancing hemostasis, separate from, and additional to, that due to increased circulating Factor VIII, and it is due to residual PvWF in the PFVIII preparation.

Concurrent measurement of the survival of two populations of rabbit platelets labeled with either two PKH lipophilic dyes or two concentrations of biotin

BACKGROUND

To avoid radioisotopic labeling and permit comparison of the survival of two platelet populations concurrently in one animal, we compared simultaneous recoveries and survival times of homologous rabbit platelets labeled in vitro with the lipophilic dyes PKH26 (red fluorescing) and PKH67 (green fluorescing) and with two levels of biotin (low, 1 microg/ml; high, 10 microg/ml).

METHODS

Blood samples were drawn up to 96 h postinfusion and analyzed by flow cytometry. Biotin-labeled samples were incubated with phycoerythrin-streptavidin before analysis.

RESULTS

Recovery of PKH26-labeled platelets at 1 h was lower (37.5%) than that of PKH67-labeled platelets (47.3%; P < 0.001). Platelet survival times were 62.4 and 61.9 h. Recoveries at 1 h of platelets labeled with two levels of biotin were similar (86.6% and 84.6%) and greater than those of PKH-labeled platelets (P < 0.001). Survival of platelets labeled with biotin did not differ (low, 83.3 h; high, 85.2 h) and was longer than for PKH-labeled platelets (P < 0.01). Labeling methods did not activate platelets (measured by P-selectin expression), nor did they affect platelet responses to adenosine diphosphate (ADP), collagen, or thrombin.

CONCLUSIONS

Labeling with two levels of biotin is superior to labeling with PKH dyes, and is useful for measuring concurrently the survival of two differing platelet populations.

IVIg inhibits reticuloendothelial system function and ameliorates murine passive-immune thrombocytopenia independent of anti-idiotype reactivity

Although the mechanism of action of intravenous immunoglobulin (IVIg) in treating antibody-dependent thrombocytopenia remains unclear, most studies have suggested that IVIg blocks the function of Fc receptors in the reticuloendothelial system (RES) and/or the protective effect may be due to the presence of variable region-reactive (anti-idiotype) antibodies within IVIg. We evaluated the effect of IVIg on platelet counts in a murine model of passively induced immune thrombocytopenia (PIT). Although IVIg was unable to neutralize the binding of two platelet-specific monoclonal antibodies to their target antigens either in vivo or in vitro, it was able to prevent PIT as well as ameliorate pre-established PIT mediated by these antibodies. IVIg adsorbed against the antibody used to induce thrombocytopenia or endogenous murine immunoglobulin also protected against PIT, indicating that antibodies with anti-idiotype activity present in IVIg are not necessary for its effective treatment of PIT. IVIg significantly blocked the ability of the RES to clear antibody-sensitized red blood cells. F(ab')2 fragments of IVIg, which are unable to block the RES but retain the idiotypic regions, were ineffective at protecting mice from PIT. Our data suggest that IVIg exerts its rapid effect by inhibiting RES function and that anti-idiotype interactions are not required.

Quantitative and qualitative assessment of human immunodeficiency virus type 1 (HIV-1)-specific CD4+ T cell immunity to gag in HIV-1-infected individuals with differential disease progression: reciprocal interferon-gamma and interleukin-10 responses

The human immunodeficiency virus type 1 (HIV-1)-specific CD4(+) T cell response was investigated in 33 untreated HIV-1-infected individuals, using highly sensitive ELISPOT assays and intracellular flow cytometry. The median frequencies of interferon (IFN)-gamma-producing HIV-1 gag-specific CD4(+) T cells did not correlate significantly with control of viral replication or progression. HIV-1 gag-specific interleukin (IL)-4-producing cells were rarely detected. Circulating frequencies of CD4(+) T cells constitutively producing IL-10, however, were significantly higher in individuals with progression or active replication. In 17 of 30 HIV-1-infected individuals, gag antigen was observed to induce IL-10 production from CD4(+) T cells. In 2 individuals, early treatment of acute HIV-1 infection "rescued" low to undetectable gag-specific IFN-gamma-producing CD4(+) T cell responses and dramatically down-regulated constitutive IL-10 production from circulating CD4(+) T cells. The detection of HIV-1-specific IL-10-inducing CD4(+) T cells in HIV-1-infected individuals suggests that HIV-1 may directly subvert specific immune responses by IL-10 induction.

Association between cholecystectomy and adenocarcinoma of the esophagus

BACKGROUND & AIMS

Barrett's esophagus, which is linked to adenocarcinoma of the esophagus, is associated with reflux of bile. Duodenogastric reflux is increased after cholecystectomy. This study aims to evaluate if cholecystectomy is associated with an increased risk of adenocarcinoma of the esophagus.

METHODS

A population-based cohort study of cholecystectomized patients in Sweden between 1965 and 1997 cross-linked with the Swedish Cancer Register.

RESULTS

Cholecystectomized patients had an increased risk of adenocarcinoma of the esophagus (standardized incidence ratio [SIR], 1.3; 95% confidence interval [CI], 1.0-1.8). Esophageal squamous-cell carcinoma was not found to be associated with cholecystectomy (SIR, 0.9; 95% CI, 0.7-1.1). Patients with gallstone disease on whom surgery was not performed did not have an increased risk of adenocarcinoma or squamous-cell carcinoma of the esophagus.

CONCLUSIONS

Cholecystectomy is associated with a moderately increased risk of adenocarcinoma of the esophagus, possibly by the toxic effect of refluxed duodenal juice on the esophageal mucosa. Further studies are needed regarding the link between bile reflux and esophageal carcinogenesis.