HIV risk behavior profiles among men who have sex with men interested in donating blood: Findings from the Assessing Donor Variability and New Concepts in Eligibility study

BACKGROUND

Individual risk assessment allows donors to be evaluated based on their own behaviors. Study objectives were to assess human immunodeficiency virus (HIV) risk behaviors in men who have sex with men (MSM) and estimate the proportion of the study population who would not be deferred for higher risk HIV sexual behaviors.

STUDY DESIGN AND METHODS

Cross-sectional survey and biomarker assessment were conducted in eight U.S. cities. Participants were sexually active MSM interested in blood donation aged 18-39 years, assigned male sex at birth. Participants completed surveys during two study visits to define eligibility, and self-reported sexual and HIV prevention behaviors. Blood was drawn at study visit 1 and tested for HIV and the presence of tenofovir, one of the drugs in oral HIV pre-exposure prophylaxis (PrEP). Associations were assessed between HIV infection status or HIV PrEP use and behaviors, including sex partners, new partners, and anal sex.

RESULTS

A total of 1566 MSM completed the visit 1 questionnaire and blood draw and 1197 completed the visit 2 questionnaire. Among 1562 persons without HIV, 789 (50.4%) were not taking PrEP. Of those not taking PrEP, 66.2% reported one sexual partner or no anal sex and 69% reported no new sexual partners or no anal sex with a new partner in the past 3 months.

CONCLUSION

The study found that questions were able to identify sexually active, HIV-negative MSM who report lower risk sexual behaviors. About a quarter of enrolled study participants would be potentially eligible blood donors using individual risk assessment questions.

Benefit-risk assessment of Covid-19 vaccine, MRNA (MRNA-1273) for males age 18-64 years

Since the authorization of the Moderna mRNA COVID-19 vaccine, real-world evidence has indicated its effectiveness in preventing COVID-19 cases. However, increased cases of mRNA vaccine-associated myocarditis/pericarditis have been reported, predominantly in young adults and adolescents. The Food and Drug Administration conducted a benefit-risk assessment to inform the review of the Biologics License Application for use of the Moderna vaccine among individuals ages 18 and older. We modeled the benefit-risk per million individuals who receive two complete doses of the vaccine. Benefit endpoints were vaccine-preventable COVID-19 cases, hospitalizations, intensive care unit (ICU) admissions, and deaths. The risk endpoints were vaccine-related myocarditis/pericarditis cases, hospitalizations, ICU admissions, and deaths. The analysis was conducted on the age-stratified male population due to data signals and previous work showing males to be the main risk group. We constructed six scenarios to evaluate the impact of uncertainty associated with pandemic dynamics, vaccine effectiveness (VE) against novel variants, and rates of vaccine-associated myocarditis/pericarditis cases on the model results. For our most likely scenario, we assumed the US COVID-19 incidence was for the week of December 25, 2021, with a VE of 30% against cases and 72% against hospitalization with the Omicron-dominant strain. Our source for estimating vaccine-attributable myocarditis/pericarditis rates was FDA's CBER Biologics Effectiveness and Safety (BEST) System databases. Overall, our results supported the conclusion that the benefits of the vaccine outweigh its risks. Remarkably, we predicted vaccinating one million 18-25 year-old males would prevent 82,484 cases, 4,766 hospitalizations, 1,144 ICU admissions, and 51 deaths due to COVID-19, comparing to 128 vaccine-attributable myocarditis/pericarditis cases, 110 hospitalizations, zero ICU admissions, and zero deaths. Uncertainties in the pandemic trajectory, effectiveness of vaccine against novel variants, and vaccine-attributable myocarditis/pericarditis rate are important limitations of our analysis. Also, the model does not evaluate potential long-term adverse effects due to either COVID-19 or vaccine-attributable myocarditis/pericarditis.

Biological therapies need definitive randomized controlled clinical trials

Adequate and well-controlled clinical trials remain critical tools for helping to bring benefit to patients in medical need.

Urgent Need for Next-Generation COVID-19 Vaccines

This Viewpoint argues that the development of a distinctly improved generation of SARS-CoV-2 vaccines is paramount to offering a greater breadth and depth of protection for a longer duration against COVID-19 disease.

Benefit-risk assessment of COVID-19 vaccine, mRNA (Comirnaty) for age 16-29 years

Since authorization of the Pfizer-BioNTech COVID-19 Vaccine, mRNA (Comirnaty), real-world evidence has indicated the vaccines are effective in preventing COVID-19 cases and related hospitalizations and deaths. However, increased cases of myocarditis/pericarditis have been reported in the United States associated with vaccination, particularly in adolescents and young adults. FDA conducted a benefit-risk assessment to determine whether the benefits of vaccination outweigh the risks among various age (16–17, 18–24, 25–29) and sex (M/F) subgroups being considered for approved use of the vaccine. We conducted a simulation study with sensitivity analysis of the benefits and risks of the vaccine across possible pandemic scenarios. The model results show benefits outweigh the risks for all scenarios including the high-risk subgroup, males 16–17 years old. Our worst-case scenario used sex and age subgroup-specific incidences for COVID-19 cases (47–98 per million per day) and hospitalizations (1–4 per million per day) which are the US COVID-19 incidences as of July 10, 2021, vaccine efficacy of 70% against COVID-19 cases and 80% against hospitalization, and unlikely, pessimistic, non-zero vaccine-attributable myocarditis death rate. For males 16–17 years old, the model predicts prevented COVID cases, hospitalizations, ICUs, and deaths of 13577, 127, 41, and 1, respectively; while the predicted ranges for excess myocarditis/pericarditis cases, hospitalizations, and deaths attributable to the vaccine are [98–196], [98–196], and 0, respectively, for the worst-case scenario. Considering the different clinical implications of hospitalization due to COVID-19 infection versus vaccine-attributable myocarditis/pericarditis cases, we determine the benefits still outweigh the risks even for this high-risk subgroup. Our results demonstrate that the benefits of the vaccine outweigh its risks for all age and sex subgroups we analyze in this study. Uncertainties exist in this assessment as both benefits and risks of vaccination may change with the continuing evolution of the pandemic.

Scientific considerations for global drug development

Requiring regional or in-country confirmatory clinical trials before approval of drugs already approved elsewhere delays access to medicines in low- and middle-income countries and raises drug costs. Here, we discuss the scientific and technological advances that may reduce the need for in-country or in-region clinical trials for drugs approved in other countries and limitations of these advances that could necessitate in-region clinical studies.

Clinical Development Strategies and Considerations for Zika Vaccine Licensure

The Zika outbreak that began in 2015 has spread from Brazil to countries across the Western Hemisphere including the United States, presenting global public health challenges that call for the expedited development and availability of preventive vaccines to protect against Zika virus disease. While the general principles guiding the nonclinical and clinical development for Zika vaccines are the same as those of other preventive vaccines, unique considerations apply, in particular if development occurs during a public health emergency. Furthermore, incomplete information about the pathogenesis of Zika virus disease and the mechanism by which candidate preventive vaccines potentially may confer protection presents additional challenges to their clinical development. Nevertheless, definition of clinical development strategies to enable sound regulatory assessment, with a goal toward licensure is critical for these products. This article will provide an overview of the regulatory considerations for the clinical development and licensure of Zika vaccine candidates including a discussion of clinical study designs, approaches to demonstrate vaccine effectiveness, and regulatory pathways to licensure.

Maintaining a Safe Blood Supply in an Era of Emerging Pathogens

Coming shortly after outbreaks of dengue and chikungunya virus in related locations, the recent outbreak of Zika virus in the southern part of the western hemisphere is yet another reminder that infectious pathogens continue to emerge rapidly and can adversely affect public health, including the safety of the blood supply. In response to Zika virus, public health measures that rely largely on donor deferral and sourcing of blood from non-outbreak areas until a blood donor screening test becomes available have been implemented to address the safety of the blood supply in the United States. However, a more universal approach to ensuring blood safety in the setting of rapidly emerging infectious diseases is needed.

Modeling complete removal of risk assessment questions in the USA predicts the risk of HIV exposure in blood recipients could increase despite the use of nucleic acid testing

BACKGROUND AND OBJECTIVES

The safety of the blood supply in a number of countries is achieved by interventions that include behaviour-based time-limited or indefinite deferrals and screening of donated units for transfusion-transmitted infections. The relatively high sensitivity of nucleic acid testing (NAT) used in blood donor screening has raised the question of whether such time-based deferrals can be eliminated in favour of individual risk assessment.

MATERIALS AND METHODS

Data on the annual number of incident human immunodeficiency virus (HIV) infections associated with various behaviours and on the performance characteristics of NAT applied to donor screening were used to model the number of potentially infected units that might escape detection in the worst-case scenario in which individual risk assessment was implemented, but was not effective as a screening tool, and donors did not otherwise self-select for lower risk.

RESULTS

In the absence of effective individual risk-based screening or donor self-selection, the model predicts that in the United States, an additional 39 (95% CI 35-43) HIV-infected units would escape detection by nucleic acid testing, potentially capable of exposing approximately 68 (95% CI 61-75) individuals to the risk of HIV infection through the administration of prepared blood components.

CONCLUSION

Despite some inherent uncertainty, the worst-case scenario of completely ineffective individual risk assessment, absence of donor self-selection and increased reliance on NAT for blood screening is estimated to be associated with an approximately fourfold increase in the risk of HIV exposure through transfusion in the United States.

Hematologic manifestations of liver disease

The liver plays a key role in both protein biosynthesis and lipid metabolism. As a result, hepatic synthetic dysfunction can have adverse effects on both cellular and soluble components of blood. Anemia may occur due to the hemolysis of acanthocytes (spur cells), which is ultimately due to abnormal lipid composition of the red blood cell membrane. Thrombocytopenia may result from several different mechanisms. Cytopenias also may be a consequence of hypersplenism. The liver is the primary site for synthesis of most procoagulant and anticoagulant proteins. The coagulopathy of liver disease is therefore complex. Early in the course of liver disease, thrombocytopenia and a coagulopathy associated with a prothrombotic state are not uncommon, whereas with more advanced disease pancytopenia and coagulopathy associated with hemorrhage become manifest. Fresh frozen plasma and adjuncts to hemostasis may be used as temporizing measures in bleeding patients. However, definitive management of many of the defects due to fulminant hepatic failure requires liver transplantation.

Relapsing and remitting severe hypoglycemia due to a monoclonal anti-insulin antibody heralding a case of multiple myeloma

CONTEXT

We report a novel case of insulin autoimmune syndrome (IAS) presenting with hypoglycemia due to production of a monoclonal anti-insulin antibody in a patient subsequently found to have multiple myeloma (MM).

OBJECTIVE

The aim of the study was to describe the 5-yr clinical course of a patient with IAS and MM and to characterize the origin and function of the pathogenic antibody.

METHODS

We conducted a longitudinal case history with laboratory investigations to characterize the anti-insulin antibody subtype, specificity, affinity, and origin.

RESULTS

The patient presented with IAS, which worsened during treatment of hepatitis C. The patient was then discovered to have a monoclonal gammopathy that progressed to MM. Treatment of the MM induced remission of the neoplasia and IAS, which then followed a synchronized course of progression and response to therapy. An anti-insulin IgG(3)-λ that bound specifically but with low affinity to the insulin B chain (amino acids 9-30) and that was distinct from the primary MM IgG(3)-κ clone was recovered from the patient and cloned. The antibody bound insulin and showed mutations of normal affinity maturation.

CONCLUSIONS

We describe a case of MM heralded by IAS, where full characterization of the pathogenic antibody revealed that the monoclonal anti-insulin antibody had originated from a self-reactive clone.

Decitabine for acute myeloid leukemia

Decitabine (Dacogen(®), Eisai Inc., NJ, USA) is a nucleoside analogue DNA methyltransferase inhibitor first synthesized and documented to have antileukemic efficacy over 40 years ago. Over the years, the dosing of decitabine has been refined, such that for acute myeloid leukemia, a 5-day schedule of 20 mg/m(2) is now commonly utilized. Owing to its relatively modest nonhematologic toxicity when administered in this manner, single agent decitabine has shown the greatest promise in antileukemic efficacy for the management of older individuals and others who are not candidates for more intensive therapy. Whether or not single-agent decitabine is more safe and effective than existing therapies for older individuals, which markers best predict for response, and what drugs combine most effectively with decitabine, are all areas of active investigation at this time.

Treatment-related myelodysplasia in patients with primary brain tumors

Treatment-related myelodysplastic syndrome (t-MDS) and treatment-related acute myelogenous leukemia (t-AML) represent rare secondary events in patients with primary tumors of the nervous system and predominantly affect those treated with alkylating agents or topoisomerase II inhibitors. Temozolomide has become the standard chemotherapeutic agent for malignant gliomas. The emergence of this alkylating agent with little acute toxicity or cumulative myelosuppression has led to off-label protracted chemotherapy for many patients with malignant and even low-grade infiltrative gliomas, raising concern for increased risk of t-MDS/t-AML in the few long-term survivors. On the basis of an extensive literature search, we provide a discussion of epidemiology, pathogenesis, clinical presentation, diagnosis, and therapy of these disorders. t-MDS/t-AML remain rare complications of chemotherapy in patients with primary brain tumors, and the vast majority of patients die of their primary neoplasm. Prospective randomized studies with long-term follow-up are required to accurately assess the risk of t-MDS/t-AML; however, unless survival in the most common gliomas substantially increases, t-MDS/t-AML incidence will likely remain low in this patient population.

Transfusion and chelation practices in sickle cell disease: a regional perspective

Although most common in tropical regions, population migration has meant that sickle cell disease is now one of the most prevalent genetic diseases worldwide. The issues and challenges faced by physicians and patients have been discussed by an international group of experts representing 4 key regions: the USA, Europe, Latin America, and the Middle East/Africa. Conclusive evidence to support the use of transfusion therapy for the prevention of stroke has resulted in key changes to patient management in all regions, and increasing numbers of patients are benefiting from this management approach. However, it is apparent that transfusion therapy is still under-utilized, largely due to concerns over iron overload, alloimmunization, limited blood supplies, and, sometimes, due to parental refusal. Once transfused, assessment and management of body iron levels can be poor, particularly in patients who are intermittently transfused. Compliance with chelation therapy regimens is a significant challenge, but new therapeutic options are likely to overcome some of the current barriers. Key requirements in all regions were considered to be the following: to provide greater physician, patient, and family education; to ensure effective transition from pediatric to adult care; and to establish national guidelines in order to ensure best practice is consistently applied.

WAG-F8(m1Ycb) rats harboring a factor VIII gene mutation provide a new animal model for hemophilia A

BACKGROUND

We recently described an inherited coagulopathy arising in an inbred colony of WAG/RijYcb rats. The bleeding phenotype, demonstrated by both male and female rats, included periarticular hemorrhage, spontaneous bruising, prolonged bleeding from minor wounds and maternal peripartum deaths. Coagulation testing of affected rats revealed normal prothrombin time but prolongation of activated partial thromboplastin time to twice that of controls.

OBJECTIVE

To determine the specific coagulation factor and the underlying genetic defect responsible for the inherited coagulopathy in the WAG/RijYcb rats.

RESULTS

Evaluation of individual clotting factor activities revealed that the affected animals had a specific deficiency of factor (F) VIII (FVIII). The FVIII gene (F8) has an autosomal location on chromosome 18 in rats, in contrast to its location on the X chromosome in mice and humans. Sequencing of F8 cDNA led to the identification of a point mutation resulting in a substitution, Leu176Pro, in the A1 domain, that is predicted to disrupt the tertiary structure of the FVIII molecule. Administration of human plasma or human recombinant FVIII corrects the coagulation abnormality in the affected animals.

CONCLUSIONS

We have now identified the genetic basis of the hemostatic defect in the WAG/RijYcb rat colony. The larger size of rats relative to mice and the presence of this coagulation defect in both sexes provide a unique model, well-suited to the development of novel therapies for acquired and hereditary FVIII deficiencies.

Decitabine combined with fractionated gemtuzumab ozogamicin therapy in patients with relapsed or refractory acute myeloid leukemia

Salvage chemotherapy for patients with relapsed or refractory acute myeloid leukemia (AML) is generally associated with a low-response rate and significant nonhematologic toxicity. Both decitabine and gemtuzumab ozogamicin have activity in AML as single agents and can be administered sequentially with potential synergy due to their toxicity profiles. Twelve patients with AML, who had received a median of three prior regimens (range 1-6), were treated with decitabine 20 mg/m(2) on days 1 through 5 followed by gemtuzumab ozogamicin 3 mg/m(2) on days 6, 9, and 12. Five patients achieved a complete response (42%) and subsequently underwent hematopoietic stem cell transplantation. Three patients are in complete remission and four are still alive 7 to 16 months after treatment. The regimen was well tolerated with the primary nonhematologic toxicity of Grade 1 or 2 transaminitis observed in four patients. These results indicate that decitabine in combination with gemtuzumab is a regimen of promising efficacy worthy of further investigation in controlled trials.

Coagulation disorders in the ICU

Disorders of hemostasis and thrombosis are frequently encountered in the ICU setting. Understanding the relevance of laboratory findings is essential in providing appropriate therapy. Various blood products and hemostatic agents are available to assist in the control of bleeding, and several different classes of anticoagulants are now available for use. Appropriate use of these agents maximizes therapeutic effect while minimizing complications. Use of fresh frozen plasma, cryoprecipitate, and other hemostatic agents should generally be reserved for those who have active bleeding, those undergoing invasive procedures, and those at high risk for bleeding because of their underlying diagnoses or because of associated hematologic derangements.

Management of thromboembolism in pregnancy

The incidence of venous thromboembolism is increased during pregnancy and the postpartum period. This risk is high for women with documented hereditary or acquired risk factors who have experienced a prior thrombotic event. These individuals require a minimum of prophylactic dose anticoagulation with unfractionated or low molecular weight heparin during pregnancy, with anticoagulation continuing for 4 to 6 weeks postpartum. Women receiving therapeutic dose anticoagulation with warfarin before pregnancy for a hereditary or acquired condition should be transitioned to therapeutic doses of unfractionated heparin or low molecular weight heparin before or within 6 weeks of becoming pregnant, and can then resume warfarin postpartum. Women experiencing a thromboembolic event during pregnancy should receive therapeutic treatment with unfractionated heparin or low molecular weight heparin during pregnancy, with anticoagulation continuing for 4 to 6 weeks postpartum, and for a total of at least 6 months.

The Effect of Excessive Anticoagulation on Mortality and Morbidity in Hospitalized Patients With Anticoagulant-Related Major Hemorrhage

BACKGROUND

We aimed to determine the effect of excessive anticoagulation on morbidity and mortality in hospitalized patients with major anticoagulant-associated hemorrhage.

METHODS

We prospectively identified 101 consecutive inpatients admitted to Brigham and Women's Hospital with major bleeding occurring during administration of warfarin sodium, unfractionated heparin (UFH), or low-molecular-weight heparin (LMWH).

RESULTS

Fifty patients had excessive and 51 had nonexcessive anticoagulation. The overall mortality at 60 days was 26% (13/50) in the excessive group compared with 10% (5/51) in the nonexcessive group (P =.03). Excessive warfarin therapy was associated with an increased 60-day mortality (P =.049), in contrast to excessive anticoagulation with UFH or LMWH alone (P =.27) or UFH or LMWH as a "bridge" to warfarin therapy (P =.10). Multivariate regression identified excessive anticoagulation as an independent predictor of 60-day mortality (adjusted hazard ratio [HR], 4.17; 95% confidence interval [CI], 1.39-12.49; P =.01), along with intracranial hemorrhage (adjusted HR, 6.16; 95% CI, 1.75-21.67; P =.005) and active cancer (adjusted HR, 3.79; 95% CI, 1.13-12.70; P =.03). Excessive anticoagulation was also a significant predictor of the combined nonfatal end point of stroke, myocardial infarction, hypotension, critical anemia, and surgical or angiographic intervention at 30 days (HR, 2.17; 95% CI, 1.25-3.78; P =.006).

CONCLUSION

In a cohort of patients with anticoagulation-associated hemorrhage, excessive anticoagulation contributed independently to increased morbidity and mortality.

Effect of thrombopoietin alone and a combination of cytochalasin B and ethylene glycol bis(β-aminoethyl ether) N,N′-tetraacetic acid-AM on the survival and function of autologous baboon platelets stored at 4°C for as long as 5 days

BACKGROUND

PLTs stored at 22 degrees C have the potential for bacterial contamination, a problem that could be reduced by 4 degrees C storage. Nevertheless, PLTs stored at 4 degrees C exhibit a significantly reduced life span. This study was performed to determine whether treatment of PLTs with thrombopoietin or cytochalasin B plus ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid (EGTA)-AM could prevent exponential loss of PLTs stored at 4 degrees C.

STUDY DESIGN AND METHODS

Autologous baboon PLTs were stored at 22 or 4 degrees C. The 4 degrees C stored PLTs were treated with 1.5 ng per mL thrombopoietin, with 1 micro mol per L cytochalasin B, and 80 micromol per L EGTA-AM (cyto-EGTA) or not treated and labeled with (111)In-oxine to study their in vivo recovery and life span. PLT function was assessed by correction of an aspirin-induced prolonged bleeding time. Aggregation responses and morphology were also assessed.

RESULTS

PLTs stored at 22 degrees C had normal in vivo recovery and linear survival. PLTs stored at 4 degrees C, whether or not they were treated with thrombopoietin, had normal recovery and exponential survival. Aggregation of cyto-EGTA-treated PLTs was similar for PLTs stored at 4 degrees C and fresh PLTs, but decreased in PLTs stored at 22 degrees C for 5 days. The addition of cyto-EGTA to PLTs before 4 degrees C storage inhibited morphologic changes that occurred in PLTs stored at 22 degrees C and cold-induced PLT clumping, but did not prevent exponential disappearance of the PLTs.

CONCLUSION

Addition of thrombopoietin or cyto-chalasin B and EGTA-AM to PLTs before 4 degrees C storage did not prevent exponential loss of PLTs.

Gemcitabine-associated thrombotic microangiopathy

BACKGROUND

Gemcitabine-associated thrombotic microangiopathy (TMA) is believed to be very rare, with an estimated incidence rate of 0.015%. Indications for gemcitabine are expanding, and comprehensive characterization of this complication is therefore important.

METHODS

The authors performed a retrospective chart review of all cases with gemcitabine-associated TMA diagnosed at Partners Healthcare System (Boston, MA) between January 1997 and February 2002.

RESULTS

Nine patients with gemcitabine-associated TMA were identified. Diagnosis was aided by clinical and laboratory features. Renal biopsy confirmed the diagnosis in two patients. The cumulative incidence of gemcitabine-associated TMA was 0.31% (8 cases among 2586 patients) when only the 8 patients with TMA who were treated at clinics associated with the current study were considered (1 patient with a TMA syndrome was transferred from another institution). The median patient age was 53 years, and the median time to development of a TMA syndrome after the initiation of gemcitabine was 8 months (range, 3-18 months), with a cumulative dose ranging from 9 to 56 g/m(2). New or exacerbated hypertension was a prominent feature in 7 of 9 patients and preceded the clinical diagnosis by 0.5-10 weeks. Treatment of TMA included discontinuation of gemcitabine, antihypertensive therapy, plasma exchange, and dialysis. Outcomes are known for all nine patients. Six patients remain alive, whereas three have died of disease progression. No patient died as a direct result of TMA, but two developed kidney failure requiring dialysis, and one developed chronic renal insufficiency.

CONCLUSIONS

In the current series, the largest single-institution study to date, the incidence of gemcitabine-associated TMA was higher than previously reported (0.31% vs. 0.015%). Seven of nine patients developed new or exacerbated hypertension, which could be a useful early identifier of patients with gemcitabine-associated TMA syndromes.

Medical management of patients with brain tumors

The most common medical problems in brain tumor patients involve the management of seizures, peritumoral edema, medication side effects, and venous thromboembolism. Despite the importance of these issues, there are very few studies specifically addressing them. Nonetheless, there has been some progress in recent years. There is increasing evidence that brain tumor patients who have not had a seizure do not benefit from prophylactic antiepileptic medications. Patients taking corticosteroids are at greater risk of Pneumocystis carinii pneumonia and may benefit from prophylactic therapy. There is also growing evidence suggesting that anticoagulation may be more effective than inferior vena cava filtration devices for treating venous thromboembolism in brain tumor patients and that the risk of hemorrhage with anticoagulation is relatively small.

Gene expression profiling of follicular lymphoma and normal germinal center B cells using cDNA arrays

Follicular lymphomas (FLs) are neoplastic counterparts of normal germinal center (GC) B cells. FLs are characterized by t(14;18) with deregulation of the Bcl-2 (BCL2) gene. The presence of t(14;18) and overexpression of Bcl-2 is necessary, but not sufficient, to cause this disease. An array containing 588 complementary DNAs (cDNAs) was used to compare the gene expression between GC B cells and FL cells. To specifically monitor genes expressed in normal GC B and FL cells and not the entire tissue compartment, normal and malignant B cells were purified from tissues. Using the array, 37 genes were up-regulated and 28 were down-regulated in FL cells as compared to normal GC B cells. The expression level of each differentially expressed gene was verified by quantitative polymerase chain reaction. Following these studies 24 genes were up-regulated and 8 genes down-regulated with a P value less than.1. Included among the genes that were up-regulated in FLs were cell cycle regulator proteins CDK10, p120, p21CIP1, and p16INK4A; transcription factors/regulators Pax-5 and Id-2, which are involved in normal B-cell development; and genes involved in cell-cell interactions, tumor necrosis factor, interleukin-2R gamma (IL-2R gamma), and IL-4R alpha. Among the genes that were down-regulated in FLs were MRP8 and MRP14, which are involved in adhesion. Interestingly, several of these genes are localized within chromosomal regions already described to be altered in FLs. These findings provide a basis for future studies into the pathogenesis and pathophysiology of FL and may lead to the identification of potential therapeutic targets as well as antigens for immunotherapeutic strategies.

Cdc42 is required for PIP(2)-induced actin polymerization and early development but not for cell viability

BACKGROUND

Cdc42 and other Rho GTPases are conserved from yeast to humans and are thought to regulate multiple cellular functions by inducing coordinated changes in actin reorganization and by activating signaling pathways leading to specific gene expression. Direct evidence implicating upstream signals and components that regulate Cdc42 activity or for required roles of Cdc42 in activation of downstream protein kinase signaling cascades is minimal, however. Also, whereas genetic analyses have shown that Cdc42 is essential for cell viability in yeast, its potential roles in the growth and development of mammalian cells have not been directly assessed.

RESULTS

To elucidate potential functions of Cdc42 mammalian cells, we used gene-targeted mutation to inactivate Cdc42 in mouse embryonic stem (ES) cells and in the mouse germline. Surprisingly, Cdc42-deficient ES cells exhibited normal proliferation and phosphorylation of mitogen- and stress-activated protein kinases. Yet Cdc42 deficiency caused very early embryonic lethality in mice and led to aberrant actin cytoskeletal organization in ES cells. Moreover, extracts from Cdc42-deficient cells failed to support phosphatidylinositol 4,5-bisphosphate (PIP(2))-induced actin polymerization.

CONCLUSIONS

Our studies clearly demonstrate that Cdc42 mediates PIP(2)-induced actin assembly, and document a critical and unique role for Cdc42 in this process. Moreover, we conclude that, unexpectedly, Cdc42 is not necessary for viability or proliferation of mammalian early embryonic cells. Cdc42 is, however, absolutely required for early mammalian development.

Targeting of a heterologous protein to a regulated secretion pathway in cultured endothelial cells

The stimulation of regulated exocytosis in vascular endothelial cells (EC) by a variety of naturally occurring agonists contributes to the interrelated processes of inflammation, thrombosis, and fibrinolysis. The Weibel-Palade body (WPB) is a well-described secretory granule in EC that contains both von Willebrand factor (vWF) and P-selectin, but the mechanisms responsible for the targeting of these proteins into this organelle remain poorly understood. Through adenoviral transduction, we have expressed human growth hormone (GH) as a model of regulated secretory protein sorting in EC. Immunofluorescence microscopy of EC infected with GH-containing recombinant adenovirus (GHrAd) demonstrated a granular distribution of GH that colocalized with vWF. In contrast, EC infected with an rAd expressing the IgG(1) heavy chain (IG), a constitutively secreted protein, did not demonstrate colocalization of IG and vWF. In response to phorbol ester, GH as well as endogenously synthesized vWF were rapidly released from GHrAd-infected EC. By immunofluorescence microscopy, granular colocalization of GH with endogenous tissue-type plasminogen activator (tPA) was also demonstrated, and most of the tPA colocalized with vWF. These data indicate that EC are capable of selectively targeting heterologous proteins, such as GH, to the regulated secretory pathway, which suggests that EC and neuroendocrine cells share common protein targeting recognition signals or receptors.

Tsc2(+/-) mice develop tumors in multiple sites that express gelsolin and are influenced by genetic background

Tuberous sclerosis (TSC) is an autosomal dominant genetic disorder in which benign hamartomas develop in multiple organs, caused by mutations in either TSC1 or TSC2. We developed a murine model of Tsc2 disease using a gene targeting approach. Tsc2-null embryos die at embryonic days 9.5-12.5 from hepatic hypoplasia. Tsc2 heterozygotes display 100% incidence of multiple bilateral renal cystadenomas, 50% incidence of liver hemangiomas, and 32% incidence of lung adenomas by 15 months of age. Progression to renal carcinoma, fatal bleeding from the liver hemangiomas, and extremity angiosarcomas all occur at a rate of less than 10%. The renal cystadenomas develop from intercalated cells of the cortical collecting duct and uniformly express gelsolin at high levels, enabling detection of early neoplastic lesions. The tumor expression pattern of the mice is influenced by genetic background, with fewer large renal cystadenomas in the outbred Black Swiss background and more angiosarcomas in 129/SvJae chimeric mice. The slow growth of the tumors in the heterozygote mice matches the limited growth potential of the great majority of TSC hamartomas, and the influence of genetic background on phenotype correlates with the marked variability in expression of TSC seen in patients.

Chloramphenicol-induced mitochondrial dysfunction is associated with decreased transferrin receptor expression and ferritin synthesis in K562 cells and is unrelated to IRE-IRP interactions

Chloramphenicol is an antibiotic that consistently suppresses the bone marrow and induces sideroblastic anemia. It is also a rare cause of aplastic anemia. These toxicities are thought to be related to mitochondrial dysfunction, since chloramphenicol inhibits mitochondrial protein synthesis. We hypothesized that chloramphenicol-induced mitochondrial impairment alters the synthesis of ferritin and the transferrin receptor. After treating K562 erythroleukemia cells with a therapeutic dose of chloramphenicol (10 microg/ml) for 4 days, there was a marked decrease in cell surface transferrin receptor expression and de novo ferritin synthesis associated with significant decreases in cytochrome c oxidase activity, ATP levels, respiratory activity, and cell growth. Decreases in the transferrin receptor and ferritin were associated with reduced and unchanged message levels, respectively. The mechanism by which mitochondrial dysfunction alters these important proteins in iron homeostasis is not clear. A global decrease in synthetic processes seems unlikely, since the expression of the cellular adhesion proteins VLA4 and CD58 was not significantly decreased by chloramphenicol, nor were the message levels of beta-actin or ferritin. The alterations were not accompanied by changes in binding of the iron response protein (IRP) to the iron-responsive element (IRE), although cytosolic aconitase activity was reduced by 27% in chloramphenicol-treated cells. A disturbance in iron homeostasis due to alterations in the transferrin receptor and ferritin may explain the hypochromic-microcytic anemia and the accumulation of nonferritin iron in the mitochondria in some individuals after chloramphenicol therapy. Also, these studies provide evidence of a link between mitochondrial impairment and iron metabolism in K562 cells.

Cofilin and gelsolin segment-1: molecular dynamics simulation and biochemical analysis predict a similar actin binding mode

An understanding of the actin-depolymerizing function attributed to members of the ADF/cofilin/destrin superfamily requires a structural model of these proteins in complex with actin. As a step toward defining actin-cofilin interactions, the complex of yeast cofilin with monomeric actin was predicted, starting with the actin-gelsolin segment-1 binding mode recently suggested for the actin-destrin complex. After refinement by molecular dynamics simulation, the structure of cofilin converged in a new binding mode that required only minimal changes induced in the actin-cofilin interface. The predicted complex exhibits strong interactions between the N termini of actin and cofilin, mediated by a salt bridge of cofilin Arg3 with actin Asp1. The forming of this salt bridge could be prevented by the phosphorylation of cofilin Ser4, which is believed to inhibit cofilin depolymerization activity. Recent mutagenesis studies, crosslinking experiments and peptide binding studies are consistent with the predicted model of the actin-cofilin complex. The structural homology between cofilin and gelsolin segment-1 binding to actin was confirmed experimentally by two types of competitive binding assays.

Advillin (p92): a new member of the gelsolin/villin family of actin regulatory proteins

A new member of the gelsolin/villin family of actin regulatory proteins was initially identified by screening an adult murine brain cDNA library with a probe for bovine adseverin. The predicted amino acid sequence of the 92 kDa murine protein p92 (advillin) is 75% homologous to villin and 65% homologous to gelsolin and adseverin. It shares a six domain structure with other gelsolin family members and has a carboxy-terminal headpiece, similar to, yet distinct from, villin. Northern blot analysis shows a high level of mRNA expression in murine uterus and human intestine. In situ mRNA analysis of adult murine tissues demonstrates that the message is most highly expressed in the endometrium of the uterus, the intestinal lining, and at the surface of the tongue. In murine embryonic development, strong expression of the message is observed by day 14.5 in dorsal root ganglia and trigeminal ganglia. Expression is also noted at day 16.5 in cerebral cortex. We propose that p92 (advillin) has unique functions in the morphogenesis of neuronal cells which form ganglia, and that it may compensate to explain the near normal phenotype observed in villin-deficient mice.

Genomic organization and chromosomal location of murine Cdc42

cdc42 is a member of the rho family of small GTPases, which are implicated as regulators of cellular morphology. To date, one murine and two human cdc42 isoforms have been identified. Here we report the cloning of a second murine isoform and provide evidence that the two isoforms arise from a single gene by alternative splicing. In contrast with the previously identified murine cdc42 sequence, which is expressed in a wide variety of tissues, the second isoform appears to be expressed exclusively in brain. Using single-strand conformation polymorphism analysis of a mouse backcross panel, the gene encoding cdc42 has been localized to distal chromosome 4.

Pulmonary embolism and deep venous thrombosis during pregnancy or oral contraceptive use: prevalence of factor V Leiden

Activated protein C resistance caused by factor V Leiden mutation is the most common inherited cause of an underlying predisposition to pulmonary embolism (PE) and deep venous thrombosis (DVT). We studied the frequency of the factor V Leiden mutation in 50 women who had PE and/or DVT during or after pregnancy or during oral contraceptive use. Ten (20%; 95% CI 10% to 34%) of the 50 women were heterozygous for the mutation. First-trimester PE or DVT developed in 6 (60%; 95% CI, 26% to 88%) of the 10 women with the mutation compared with 3 (8%; 95% CI 2% to 20%) of 40 women without the mutation (p = 0.0009). These data indicate that the factor V Leiden mutation is an important risk factor for PE or DVT during pregnancy (especially the first trimester), after pregnancy, or during oral contraceptive use.

Congenital dyserythropoietic anemias

The congenital dyserythropoietic anemias (CDAs) are a group of relatively rare inherited anemias that share in common ineffective erythropoiesis and morphologic abnormalities of mature red blood cells and their precursors. Three major types of CDA and a number of variants have been described. The diagnosis and categorization of these disorders are facilitated by microscopic examination of the blood and bone marrow and by serologic testing. Management of patients currently consists of observation and supportive care. Because patients with CDAs may be at significant risk for secondary hemochromatosis, they require monitoring for this condition. Splenectomy may be of benefit in certain cases in which the anemia is particularly severe. Over the past few years advances have been made in understanding the pathogenesis of these disorders, and it now appears that CDA II results from enzymatic defects in the cellular glycosylation pathway.

An information system to improve the safety and efficiency of chemotherapy ordering

We developed a computer application to support the ordering of chemotherapy. Key goals were to guard against errors in chemotherapy ordering and dosing, to, coordinate the outpatient and inpatient chemotherapy services, and to support the overall process flow of a chemotherapy cycle. In a six-month period, 512 daily-dose and 386 weekly-dose warnings were generated; 167 (19%) resulted in a cancellation or re-evaluation of the dose. The system has been well accepted, and has helped to coordinate the efforts of the many members of the oncology care team.

Usefulness of bone marrow examination in the evaluation of unexplained fevers in patients infected with human immunodeficiency virus

The diagnostic usefulness of 69 bone marrow examinations (BMEs) performed for evaluating unexplained fever in 65 persons who were infected with human immunodeficiency virus was retrospectively compared with the usefulness of other diagnostic modalities used to investigate the cause of fever. An etiology for the fever was identified by BME in 22 of the 69 cases (diagnostic yield, 32%). In 19 of these 22 cases, the same diagnosis had been made by another diagnostic modality, but the diagnosis was made by BME as rapidly or sooner in 10 of the 19 cases and was made exclusively by BME in the three other cases. We suggest that BME is indicated when a diagnosis is urgently sought or when an evaluation with other diagnostic modalities has been unsuccessful.