A viral-specific CD4+ T cell response protects female mice from Coxsackievirus B3 infection

Background

Biological sex plays an integral role in the immune response to various pathogens. The underlying basis for these sex differences is still not well defined. Here, we show that Coxsackievirus B3 (CVB3) induces a viral-specific CD4+ T cell response that can protect female mice from mortality.

Methods

We inoculated C57BL/6 Ifnar-/- mice with CVB3. We investigated the T cell response in the spleen and mesenteric lymph nodes in male and female mice following infection.

Results

We found that CVB3 can induce expansion of CD62Llo CD4+ T cells in the mesenteric lymph node and spleen of female but not male mice as early as 5 days post-inoculation, indicative of activation. Using a recombinant CVB3 virus expressing a model CD4+ T cell epitope, we found that this response is due to viral antigen and not bystander activation. Finally, the depletion of CD4+ T cells before infection increased mortality in female mice, indicating that CD4+ T cells play a protective role against CVB3 in our model.

Conclusions

Overall, these data demonstrated that CVB3 can induce an early CD4 response in female but not male mice and further emphasize how sex differences in immune responses to pathogens affect disease.

A viral-specific CD4 + T cell response protects female mice from Coxsackievirus B3 infection

Biological sex plays an integral role in the immune response to various pathogens. The underlying basis for these sex differences is still not well defined. Here, we show that Coxsackievirus B3 (CVB3) induces a viral-specific CD4 + T cell response that can protect female mice from mortality. We found that CVB3 can induce expansion of CD62L lo CD4 + T cells in the mesenteric lymph node and spleen of female but not male mice as early as 5 days post-inoculation, indicative of activation. Using a recombinant CVB3 virus expressing a model CD4 + T cell epitope, we found that this response is due to viral antigen and not bystander activation. Finally, the depletion of CD4 + T cells before infection increased mortality in female mice, indicating that CD4 + T cells play a protective role against CVB3 in our model. Overall, these data demonstrated that CVB3 can induce an early CD4 response in female but not male mice and further emphasize how sex differences in immune responses to pathogens affect disease outcomes.

Molecular, metabolic, and functional CD4 T cell paralysis in the lymph node impedes tumor control

CD4 T cells are central effectors of anti-cancer immunity and immunotherapy, yet the regulation of CD4 tumor-specific T (TTS) cells is unclear. We demonstrate that CD4 TTS cells are quickly primed and begin to divide following tumor initiation. However, unlike CD8 TTS cells or exhaustion programming, CD4 TTS cell proliferation is rapidly frozen in place by a functional interplay of regulatory T cells and CTLA4. Together these mechanisms paralyze CD4 TTS cell differentiation, redirecting metabolic circuits, and reducing their accumulation in the tumor. The paralyzed state is actively maintained throughout cancer progression and CD4 TTS cells rapidly resume proliferation and functional differentiation when the suppressive constraints are alleviated. Overcoming their paralysis established long-term tumor control, demonstrating the importance of rapidly crippling CD4 TTS cells for tumor progression and their potential restoration as therapeutic targets.

Impact of reduced nicotine content on behavioral economic measures of cigarette reinforcement in adolescents who smoke cigarettes

BACKGROUND

Public health officials in the U.S. and New Zealand are considering a reduced nicotine standard for cigarettes to reduce their addictive potential. This study's aim was to evaluate the effects of nicotine reduction on the reinforcing efficacy of cigarettes in adolescents who smoke, which has implications for this policy's potential for success.

METHODS

Adolescents who smoked cigarettes daily (n = 66; mean age: 18.6) participated in a randomized clinical trial assessing effects of assignment to very low nicotine content (VLNC; 0.4 mg/g nicotine) or normal nicotine content (NNC; 15.8 mg/g nicotine) cigarettes. Hypothetical cigarette purchase tasks were completed at baseline and the end of Week 3 and demand curves fit to the data. Linear regressions estimated effects of nicotine content on demand for study cigarettes at baseline and Week 3 and associations between baseline demand for cigarette consumption at Week 3.

RESULTS

An extra sum of squares F-test of fitted demand curves indicated that demand (α) was more elastic among VLNC participants at baseline and Week 3 (F(2, 1016)= 35.72, p < 0.001). Adjusted linear regressions indicated demand was more elastic (ß= 1.45, p < 0.01) and maximum expenditure (Omax) lower (ß= -1.42, p-0.03) among VLNC participants at Week 3. More elastic demand for study cigarettes at baseline predicted lower consumption of cigarettes at Week 3 (p's < 0.01).

CONCLUSIONS

A nicotine reduction policy may reduce the reinforcing value of combustible cigarettes among adolescents. Future work should investigate likely responses to such a policy among youth with other vulnerabilities and evaluate the potential for substitution to other nicotine containing products.

Molecular, metabolic and functional CD4 T cell paralysis impedes tumor control

CD4 T cells are important effectors of anti-tumor immunity, yet the regulation of CD4 tumor-specific T (T TS ) cells during cancer development is still unclear. We demonstrate that CD4 T TS cells are initially primed in the tumor draining lymph node and begin to divide following tumor initiation. Distinct from CD8 T TS cells and previously defined exhaustion programs, CD4 T TS cell proliferation is rapidly frozen in place and differentiation stunted by a functional interplay of T regulatory cells and both intrinsic and extrinsic CTLA4 signaling. Together these mechanisms paralyze CD4 T TS cell differentiation, redirecting metabolic and cytokine production circuits, and reducing CD4 T TS cell accumulation in the tumor. Paralysis is actively maintained throughout cancer progression and CD4 T TS cells rapidly resume proliferation and functional differentiation when both suppressive reactions are alleviated. Strikingly, Treg depletion alone reciprocally induced CD4 T TS cells to themselves become tumor-specific Tregs, whereas CTLA4 blockade alone failed to promote T helper differentiation. Overcoming their paralysis established long-term tumor control, demonstrating a novel immune evasion mechanism that specifically cripples CD4 T TS cells to favor tumor progression.

The transcription factor IRF2 drives interferon-mediated CD8+ T cell exhaustion to restrict anti-tumor immunity

Type I and II interferons (IFNs) stimulate pro-inflammatory programs that are critical for immune activation, but also induce immune-suppressive feedback circuits that impede control of cancer growth. Here, we sought to determine how these opposing programs are differentially induced. We demonstrated that the transcription factor interferon regulatory factor 2 (IRF2) was expressed by many immune cells in the tumor in response to sustained IFN signaling. CD8+ T cell-specific deletion of IRF2 prevented acquisition of the T cell exhaustion program within the tumor and instead enabled sustained effector functions that promoted long-term tumor control and increased responsiveness to immune checkpoint and adoptive cell therapies. The long-term tumor control by IRF2-deficient CD8+ T cells required continuous integration of both IFN-I and IFN-II signals. Thus, IRF2 is a foundational feedback molecule that redirects IFN signals to suppress T cell responses and represents a potential target to enhance cancer control.

CD4+ progenitor cells sustain helper responses during chronic infection

How CD4⁺ T cell responses are maintained during chronic infection is unknown. In this issue of Immunity, Xia et al. (2022) identify a progenitor T cell subset that gives rise to effector and follicular helper T cells to sustain antiviral responses.

Dynamic CD4+ T cell heterogeneity defines subset-specific suppression and PD-L1-blockade-driven functional restoration in chronic infection

Inhibiting PD-1:PD-L1 signaling has transformed therapeutic immune restoration. CD4+ T cells sustain immunity in chronic infections and cancer, yet little is known about how PD-1 signaling modulates CD4+ helper T (TH) cell responses or the ability to restore CD4+ TH-mediated immunity by checkpoint blockade. We demonstrate that PD-1:PD-L1 specifically suppressed CD4+ TH1 cell amplification, prevents CD4+ TH1 cytokine production and abolishes CD4+ cytotoxic killing capacity during chronic infection in mice. Inhibiting PD-L1 rapidly restored these functions, while simultaneously amplifying and activating TH1-like T regulatory cells, demonstrating a system-wide CD4-TH1 recalibration. This effect coincided with decreased T cell antigen receptor signaling, and re-directed type I interferon (IFN) signaling networks towards dominant IFN-γ-mediated responses. Mechanistically, PD-L1 blockade specifically targeted defined populations with pre-established, but actively suppressed proliferative potential, with limited impact on minimally cycling TCF-1+ follicular helper T cells, despite high PD-1 expression. Thus, CD4+ T cells require unique differentiation and functional states to be targets of PD-L1-directed suppression and therapeutic restoration.

Associations Between Nicotine Knowledge and Smoking Cessation Behaviors among U.S. Adults Who Smoke

INTRODUCTION

Misperceptions about nicotine's contribution to smoking-related health harms could complicate efforts to reduce the public health burden of smoking. Study goals were to describe nicotine knowledge among adults who smoke and investigate whether misperceiving nicotine as a source of health harm was associated with beneficial health behaviors, or lower uptake of using less harmful sources of nicotine to support smoking cessation attempts.

METHOD

This study used longitudinal data from 9,140 adults who participated in four waves of the Population Assessment of Tobacco and Health Study and were current smokers during the first wave. Logistic regressions estimated odds ratios for correct responses across six aspects of nicotine knowledge assessed in Wave 4. Longitudinal models estimated associations between misperceptions and cigarette consumption, and odds of making a quit attempt; self-reported cessation; e-cigarette use; and use of NRT or e-cigarettes to support quit attempts.

RESULTS

Participants who were non-White, older, and had lower educational attainment or income tended to be least knowledgeable about nicotine. Misperceiving nicotine as harmful to health was associated with increased odds of quit attempts (AOR: 1.12, 95% CI: 1.03, 1.23), lower odds of cessation success (AOR: 0.84, 95% CI: 0.73, 0.98) and e-cigarette use (AOR: 0.79, 95% CI: 0.72, 0.86), and lower odds of using NRT (AOR: 0.84, 95% CI: 0.71, 0.99) or e-cigarettes to support quit attempts (AOR: 0.59, 95% CI: 0.49, 0.71).

CONCLUSION

Harm reduction efforts may be impeded by misperceptions about nicotine. Further work should evaluate the effects of correcting such misperceptions through public education.

IMPLICATIONS

This study provides longitudinal evidence that among adult smokers, misperceiving nicotine as a primary cause of smoking-related diseases may be associated with reduced cessation success and lower likelihood of using less harmful nicotine products. These misperceptions may therefore impede efforts to encourage smokers ready to quit to use evidence-based cessation support such as nicotine replacement during quit attempts and limit the success of policies designed to shift smokers to less harmful sources of nicotine. Further work should evaluate the longitudinal effects of correcting nicotine misperceptions through public education targeted toward adults who smoke.

Uncovering the underlying immune perturbations that determine long-term severity of chronic virus and Mycobacterium tuberculosis coinfection

Chronic viral infections increase severity of Mycobacterium tuberculosis (Mtb) coinfection, yet how they alter the pulmonary microenvironment to foster coinfection and worsen disease severity is unclear. We developed a coinfection model in mice with chronic lymphocytic choriomeningitis virus and Mtb coinfection that recapitulated the central clinical manifestations of coinfection, including increased Mtb burden, extra-pulmonary dissemination and heightened mortality. These long-term disease consequences were not due to chronic virus-induced immunosuppression or exhaustion, but instead were determined by early alterations in immune surveillance of Mtb coinfection. Mechanistically, increased chronic virus induced TNFα production initially arrested pulmonary Mtb growth, impeding dendritic cell mediated antigen transportation to the lung-draining lymph nodes (LNs) and allowing bacterial sanctuary. The inhibited antigen arrival to LNs delayed CD4 T cell priming, allowing Mtb to replicate to higher set-points before T cell mediated control could be initiated. Once primed, Mtb-specific CD4 T cell differentiation skewed away from the Th1 responses associated with Mtb control, and instead toward Th17 differentiation. The elevated IL17 increased pulmonary neutrophil influx that decreased the long-term survival of coinfected mice. Therapeutically correcting the timing of CD4 T cell priming re-established CD4 Th1 over Th17 dominance, diminished pulmonary neutrophilia, and enabled enhanced Mtb control in the presence of chronic viral coinfection. Thus, Mtb co-opts TNFα from the chronic inflammatory environment to subvert immune-surveillance, avert early immune function and foster long-term coinfection.

A network of immune and microbial modifications underlies viral persistence in the gastrointestinal tract

Many pathogens subvert intestinal immunity to persist within the gastrointestinal tract (GIT); yet, the underlying mechanisms that enable sanctuary specifically in this reservoir are unclear. Using mass cytometry and network analysis, we demonstrate that chronic LCMV infection of the GIT leads to dysregulated microbial composition, a cascade of metabolic alterations, increased susceptibility to GI disease, and a system-wide recalibration of immune composition that defines viral persistence. Chronic infection led to outgrowth of activated Tbet–expressing T reg cell populations unique to the GIT and the rapid erosion of pathogen-specific CD8 tissue-resident memory T cells. Mechanistically, T reg cells and coinhibitory receptors maintained long-term viral sanctuary within the GIT, and their targeting reactivated T cells and eliminated this viral reservoir. Thus, our data provide a high-dimensional definition of the mechanisms of immune regulation that chronic viruses implement to exploit the unique microenvironment of the GIT and identify T reg cells as key modulators of viral persistence in the intestinal tract.

Chronic virus infection drives CD8 T cell-mediated thymic destruction and impaired negative selection

Chronic infection provokes alterations in inflammatory and suppressive pathways that potentially affect the function and integrity of multiple tissues, impacting both ongoing immune control and restorative immune therapies. Here we demonstrate that chronic lymphocytic choriomeningitis virus infection rapidly triggers severe thymic depletion, mediated by CD8 T cell-intrinsic type I interferon (IFN) and signal transducer and activator of transcription 2 (Stat2) signaling. Occurring temporal to T cell exhaustion, thymic cellularity reconstituted despite ongoing viral replication, with a rapid secondary thymic depletion following immune restoration by anti-programmed death-ligand 1 (PDL1) blockade. Therapeutic hematopoietic stem cell transplant (HSCT) during chronic infection generated new antiviral CD8 T cells, despite sustained virus replication in the thymus, indicating an impairment in negative selection. Consequently, low amounts of high-affinity self-reactive T cells also escaped the thymus following HSCT during chronic infection. Thus, by altering the stringency and partially impairing negative selection, the host generates new virus-specific T cells to replenish the fight against the chronic infection, but also has the potentially dangerous effect of enabling the escape of self-reactive T cells.

CD8+ T Cell Priming in Established Chronic Viral Infection Preferentially Directs Differentiation of Memory-like Cells for Sustained Immunity

CD8⁺ T cell exhaustion impedes control of chronic viral infection; yet how new T cell responses are mounted during chronic infection is unclear. Unlike T cells primed at the onset of infection that rapidly differentiate into effectors and exhaust, we demonstrate that virus-specific CD8⁺ T cells primed after establishment of chronic LCMV infection preferentially generate memory-like transcription factor TCF1⁺ cells that were transcriptionally and proteomically distinct, less exhausted, and more responsive to immunotherapy. Mechanistically, adaptations of antigen-presenting cells and diminished T cell signaling intensity promoted differentiation of the memory-like subset at the expense of rapid effector cell differentiation, which was now highly dependent on IL-21-mediated CD4⁺ T cell help for its functional generation. Chronic viral infection similarly redirected de novo differentiation of tumor-specific CD8⁺ T cells, ultimately preventing cancer control. Thus, targeting these T cell stimulatory pathways could enable strategies to control chronic infection, tumors, and enhance immunotherapeutic efficacy.

Priming of CD8 T cells in established chronic viral infection directs a distinct differentiation and functional program for long-term immunity

CD8 T cell exhaustion impedes control of chronic virus infection, yet how CD8 T cell fate decisions and function are instilled and progressively controlled throughout infection is unclear. We demonstrate that in contrast to T cells primed at the onset of persistent viral infection, CD8 T cells primed after the chronic infection is established preferentially generate into memory-like cells that resist contraction, are less exhausted and have heightened responsiveness to immunotherapy. Mechanistically, viral persistence down-regulates APC activation machinery, decreasing T cell intrinsic TCR and CD28 signaling upon priming. The lower signal intensity provides the required threshold for activation and proliferation, but alters transcriptional programming and cellular differentiation to enable long-term retention of antiviral functions despite high levels of virus replication. In the absence of strong antigenic signaling, IL-21 acquires the ability to induce functional effectors, while preserving the memory-like reservoir. Analogous mechanisms also govern differentiation of anti-tumor CD8 T cells in the tumor microenvironment during chronic viral infection, undermining tumor control. Thus, dynamic changes in signal intensity and IL-21 usage during chronic infection function as fate-assigning rheostats to resist exhaustion and program long-term immunity.

Overcoming CD4 Th1 Cell Fate Restrictions to Sustain Antiviral CD8 T Cells and Control Persistent Virus Infection

Viral persistence specifically inhibits CD4 Th1 responses and promotes Tfh immunity, but the mechanisms that suppress Th1 cells and the disease consequences of their loss are unclear. Here, we demonstrate that the loss of CD4 Th1 cells specifically leads to progressive CD8 T cell decline and dysfunction during viral persistence. Therapeutically reconstituting CD4 Th1 cells restored CD4 T cell polyfunctionality, enhanced antiviral CD8 T cell numbers and function, and enabled viral control. Mechanistically, combined interaction of PD-L1 and IL-10 by suppressive dendritic cell subsets inhibited new CD4 Th1 cells in both acute and persistent virus infection, demonstrating an unrecognized suppressive function for PD-L1 in virus infection. Thus, the loss of CD4 Th1 cells is a key event leading to progressive CD8 T cell demise during viral persistence with important implications for restoring antiviral CD8 T cell immunity to control persistent viral infection.

CD30 Is Dispensable for T-Cell Responses to Influenza Virus and Lymphocytic Choriomeningitis Virus Clone 13 but Contributes to Age-Associated T-Cell Expansion in Mice

CD30 is a tumor necrosis factor receptor (TNFR) family member whose expression is associated with Hodgkin’s disease, anaplastic large cell lymphomas, and other T and B lymphoproliferative disorders in humans. A limited number of studies have assessed the physiological role of CD30/CD30 ligand interactions in control of infection in mice. Here, we assess the role of CD30 in T-cell immunity to acute influenza and chronic lymphocytic choriomeningitis virus (LCMV) clone 13 infection, two viral infections in which other members of the TNFR superfamily are important for T-cell responses. We show that CD30 is expressed on activated but not resting CD4 and CD8 T cells in vitro, as well as on regulatory T cells and marginally on T helper 1 cells in vivo during influenza infection. Despite this, CD4 and CD8 T-cell expansion in response to influenza virus was comparable in CD30^+/+ and CD30^−/− littermates, with no discernable role for the pathway in the outcome of influenza infection. Similarly, during persistent infection with LCMV clone 13, CD30 plays no obvious role in CD4 or CD8 T-cell responses, the level of T-cell exhaustion or viral control. In contrast, in the steady state, we observed increased numbers of total CD4 and CD8 T cells as well as increased numbers of regulatory T cells in unimmunized older (~8 months) CD30^+/+ but not in CD30^−/− age-matched littermates. Naive T-cell numbers were unchanged in the aged CD30^+/+ mice compared to their CD30^−/− littermate controls, rather the T-cell expansions were explained by an increase in CD4⁺ and CD8⁺ CD44^mid-hiCD62L⁻ effector memory cells, with a similar trend in the central memory T-cell compartment. In contrast, CD30 did not impact the numbers of T cells in young mice. These data suggest a role for CD30 in the homeostatic regulation of T cells during aging, contributing to memory T-cell expansions, which may have relevance for CD30 expression in human T-cell lymphoproliferative diseases.

Type I Interferon in Chronic Virus Infection and Cancer

Type I interferons (IFN-Is) are emerging as key drivers of inflammation and immunosuppression in chronic infection. Control of these infections requires IFN-I signaling; however, prolonged IFN-I signaling can lead to immune dysfunction. IFN-Is are also emerging as double-edged swords in cancer, providing necessary inflammatory signals, while initiating feedback suppression in both immune and cancer cells. Here, we review the proinflammatory and suppressive mechanisms potentiated by IFN-Is during chronic virus infections and discuss the similar, newly emerging dichotomy in cancer. We then discuss how this understanding is leading to new therapeutic concepts and immunotherapy combinations. We propose that, by modulating the immune response at its foundation, it may be possible to widely reshape immunity to control these chronic diseases.

Overcoming CD4 T helper cell fate restrictions to enhance CD8 T cell and B cell immunity to control persistent LCMV infection

Persistent viral infection inhibits CD4 Th1 responses, resulting in loss of the CD8 T cell helping Th1 subset and accumulation of B cell helping Tfh cells. Yet, the mechanisms that inhibit CD4 Th1 differentiation and the repercussions of loss of Th1 cells on viral control are unclear. Herein, we demonstrate that the dual upregulation of PD-L1 and IL-10 by chronic type I interferon (IFN-I) signaling during persistent infection suppresses CD4 Th1 priming. Therapeutic blockade of IL-10R and PD-L1 could restore the differentiation of new CD4 Th1 cells, highlighting a new function for PD-L1 to co-inhibit CD4 Th1 priming and identifying a new combinatorial suppressive mechanism during persistent infection. However, CD4 Th1 cells generated by blocking IFN-I signaling in vivo could not be sustained, giving way to a Tfh based response and predominant help to B cells. In vitro polarized virus-specific CD4 Th1 cells also converted towards Tfh cells, however maintained a population of Th1 cells that could enhance exhausted CD8 T cell responses and promote augmented viral clearance. Interestingly, virus-specific CD4 Th17 and Treg cells were also redirected towards Tfh as persistent infection progressed. Thus, our studies have important implications for stability of de novo activated and immunotherapeutic T cells and demonstrate that the redirection away from Th1 responses is a mechanism of immunosuppression to limit the control of persistent viral infection.

Type I and Type II Interferon Coordinately Regulate Suppressive Dendritic Cell Fate and Function during Viral Persistence

Persistent viral infections are simultaneously associated with chronic inflammation and highly potent immunosuppressive programs mediated by IL-10 and PDL1 that attenuate antiviral T cell responses. Inhibiting these suppressive signals enhances T cell function to control persistent infection; yet, the underlying signals and mechanisms that program immunosuppressive cell fates and functions are not well understood. Herein, we use lymphocytic choriomeningitis virus infection (LCMV) to demonstrate that the induction and functional programming of immunosuppressive dendritic cells (DCs) during viral persistence are separable mechanisms programmed by factors primarily considered pro-inflammatory. IFNγ first induces the de novo development of naive monocytes into DCs with immunosuppressive potential. Type I interferon (IFN-I) then directly targets these newly generated DCs to program their potent T cell immunosuppressive functions while simultaneously inhibiting conventional DCs with T cell stimulating capacity. These mechanisms of monocyte conversion are constant throughout persistent infection, establishing a system to continuously interpret and shape the immunologic environment. MyD88 signaling was required for the differentiation of suppressive DCs, whereas inhibition of stimulatory DCs was dependent on MAVS signaling, demonstrating a bifurcation in the pathogen recognition pathways that promote distinct elements of IFN-I mediated immunosuppression. Further, a similar suppressive DC origin and differentiation was also observed in Mycobacterium tuberculosis infection, HIV infection and cancer. Ultimately, targeting the underlying mechanisms that induce immunosuppression could simultaneously prevent multiple suppressive signals to further restore T cell function and control persistent infections.

Persistent virus infections induce host derived immunosuppressive factors that attenuate the immune response and prevent control of infection. Although the mechanisms of T cell exhaustion are being defined, we know surprisingly little about the underlying mechanisms that induce the immunosuppressive state and the origin and functional programming of the cells that deliver these signals to the T cells. We recently demonstrated that type I interferon (IFN-I) signaling was responsible for many of the immune dysfunctions associated with persistent virus infection and in particular the induced expression of the suppressive factors IL-10 and PDL1 by dendritic cells (DCs). Yet, mechanistically how IFN-I signaling specifically generates and programs cells to become immunosuppressive is still unknown. Herein, we define the underlying mechanisms of IFN-I mediated immunosuppression and establish that the induction of factors and the generation of the DCs that express them are separable events integrally reliant on additional inflammatory factors. Further, we demonstrate a similar derivation of the suppressive DCs that emerge in other diseases associated with prolonged inflammation and immunosuppression, specifically in HIV infection, Mycobacterium tuberculosis, and cancer, indicating a conserved origin of immunosuppression and suggesting that targeting the pathways that underlie expression of immunosuppressive cells and factors could be beneficial to treat multiple chronic diseases.

New insights into type I interferon and the immunopathogenesis of persistent viral infections

Most viruses generate potent T cell responses that rapidly control infection. However, certain viruses can subvert the immune response to establish persistent infections. The inability to clear virus induces an immunosuppressive program leading to the sustained expression of many immunoregulatory molecules that down-regulate T cell responses. Further, viral persistence is associated with multiple immune dysfunctions including lymphoid disorganization, defective antigen presentation, aberrant B cell responses and hypergammaglobulinemia. Although best known for its antiviral activity, recent data has highlighted the role of type I IFN (IFN-I) signaling as a central mediator of immunosuppression during viral persistence. It is also becoming increasingly apparent that many of the immune dysfunctions during persistent virus infection can be attributed directly or indirectly to the effects of chronic IFN-I signaling. This review explores the increasingly complex role of IFN-I in the regulation of immunity against persistently replicating virus infections and examines current and potential uses of IFN-I and blockade of IFN-I signaling to dampen chronic inflammation and activation in the clinic.

Networking at the level of host immunity: immune cell interactions during persistent viral infections

Persistent viral infections are the result of a series of connected events that culminate in diminished immunity and the inability to eliminate infection. By building our understanding of how distinct components of the immune system function both individually and collectively in productive versus abortive responses, new potential therapeutic targets can be developed to overcome immune dysfunction and thus fight persistent infections. Using lymphocytic choriomeningitis virus (LCMV) as a model of a persistent virus infection and drawing parallels to persistent human viral infections such as human immunodeficiency virus (HIV) and hepatitis C virus (HCV), we describe the cellular relationships and interactions that determine the outcome of initial infection and highlight immune targets for therapeutic intervention to prevent or treat persistent infections. Ultimately, these findings will further our understanding of the immunologic basis of persistent viral infection and likely lead to strategies to treat human viral infections.

Contribution of 4-1BBL on radioresistant cells in providing survival signals through 4-1BB expressed on CD8⁺ memory T cells in the bone marrow

The persistence of memory lymphocytes is a critical feature of adaptive immunity. The TNF family ligand 4-1BBL supports the antigen-independent survival of CD8⁺ memory T cells. Here, we show that mice lacking 4-1BB only on αβ T cells show a similar defect in CD8⁺ T-cell recall responses, as previously shown in 4-1BBL-deficient mice. We show that 4-1BB is selectively expressed on BM CD8⁺ but not CD4⁺ memory T cells of unimmunized mice. Its ligand, 4-1BBL, is found on VCAM-1⁺ stromal cells, CD11c⁺ cells, and a Gr1(lo) myeloid population in unimmunized mice. Adoptive transfer of in vitro generated memory T cells into mice lacking 4-1BBL only on radioresistant cells recapitulates the defect in CD8⁺ T-cell survival seen in the complete knockout mice, with smaller effects of 4-1BBL on hematopoietic cells. In BM, adoptively transferred DsRed CD8⁺ memory T cells are most often found in proximity to VCAM-1⁺ cells or Gr1⁺ cells, followed by B220⁺ cells and to a much lesser extent near CD11c⁺ cells. Thus, a VCAM-1⁺CD45(-) stromal cell is a plausible candidate for the radioresistant cell that provides 4-1BBL to CD8⁺ memory T cells in the BM.

Opposing roles for TRAF1 in the alternative versus classical NF-κB pathway in T cells

T cells lacking TRAF1 hyperproliferate in response to T cell receptor signaling but have impaired signaling downstream of specific TNFR family members such as 4-1BB. Here we resolve this paradox by showing that while TRAF1 is required for maximal activation of the classical NF-κB pathway downstream of 4-1BB in primary T cells, TRAF1 also restricts the constitutive activation of NIK in anti-CD3-activated T cells. Activation of the alternative NF-κB pathway is restricted in unstimulated cells by a cIAP1/2:TRAF2:TRAF3:NIK complex. Using knockdown of NIK by siRNA we show that in activated CD8 T cells TRAF1 is also involved in this process and that constitutive activation of the alternative NF-κB pathway is responsible for costimulation independent hyperproliferation and excess cytokine production in TRAF1-deficient CD8 T cells compared with WT CD8 T cells. The T cell costimulatory molecule 4-1BB critically regulates the survival of activated and memory CD8 T cells. We demonstrate that stimulation through 4-1BB induces cIAP1-dependent TRAF3 degradation and activation of the alternative NF-κB pathway. We also show that while both TRAF1 and cIAP1 have non-redundant roles in suppressing the alternative NF-κB pathway in T cells activated in the absence of costimulation, activation of the classical NF-κB pathway downstream of 4-1BB requires TRAF1, whereas cIAP1 plays a redundant role with cIAP2. Collectively these results demonstrate that TRAF1 plays a critical role in regulating T cell activation both through restricting the costimulation independent activation of NIK in activated T cells and by promoting the 4-1BB-induced classical NF-κB pathway.

T-cell intrinsic effects of GITR and 4-1BB during viral infection and cancer immunotherapy

GITR [glucocorticoid inducible tumor necrosis factor receptor (TNFR)-related protein] and 4-1BB are costimulatory TNFR family members that are expressed on regulatory and effector T cells as well as on other cells of the immune system. Here we discuss the role of GITR and 4-1BB on T cells during viral infections and in cancer immunotherapy. Systemic treatment with agonistic anti-4-1BB antibody leads to a number of immune system abnormalities, and clinical trials of anti-4-1BB have been terminated. However, other modes of 4-1BB ligation may be less toxic. To date, similar toxicities have not been reported for anti-GITR treatment of mice, although anti-GITR antibodies can exacerbate mouse autoimmune models. Intrinsic effects of GITR and 4-1BB on effector T cells appear to predominate over their effects on other cell types in some models. Despite their similarities in enhancing T-cell survival, 4-1BB and GITR are clearly not redundant, and both pathways are required for maximal CD8(+) T-cell responses and mouse survival following severe respiratory influenza infection. GITR uses TNFR-associated factor (TRAF) 2 and TRAF5, whereas 4-1BB recruits TRAF1 and TRAF2 to mediate survival signaling in T cells. The differential use of signaling adapters combined with their differential expression may explain the non-redundant roles of GITR and 4-1BB in the immune system.

Endogenous 4-1BB ligand plays a critical role in protection from influenza-induced disease

A critical issue during severe respiratory infection is whether it is the virus or the host response that does the most damage. In this study, we show that endogenous 4-1BBL plays a critical role in protecting mice from severe effects of influenza disease. During mild respiratory influenza infection in which virus is rapidly cleared, the inducible costimulatory receptor 4-1BB is only transiently induced on lung T cells and 4-1BB ligand (4-1BBL) is completely dispensable for the initial CD8 T cell response and mouse survival. In contrast, during more severe respiratory influenza infection with prolonged viral load, 4-1BB expression on lung CD8 T cells is sustained, and 4-1BBL-deficient mice show decreased CD8 T cell accumulation in the lungs, decreased viral clearance, impaired lung function, and increased mortality. Transfer of an optimal number of naive Ag-specific T cells before infection protects wild-type but not 4-1BBL-deficient mice from an otherwise lethal dose of influenza virus. Transfer of T cells lacking the proapoptotic molecule Bim extends the lifespan of 4-1BBL-deficient mice by one to three days, suggesting that at least part of the role of 4-1BB/4-1BBL is to prolong effector cell survival long enough to clear virus. Intranasal delivery of 4-1BBL by recombinant adenovirus marginally improves survival of 4-1BBL-deficient mice at low dose, but exacerbates disease at high dose. These findings suggest a rationale for the evolutionary accumulation of inducible costimulatory molecules, thereby allowing the immune system to sustain the expression of molecules such as 4-1BB to a level commensurate with severity of infection.

TNF family ligands define niches for T cell memory

Immunological memory is a critical feature of the adaptive immune system and the underlying principal behind vaccination. The mechanisms that maintain memory T cell survival between the initial and subsequent encounter with antigen remain incompletely defined. Although the cytokines IL-15 and IL-7 are important in memory T cell homeostasis, additional signals by way of TNFR family members are required for maximal maintenance of T cell memory. Here we propose a unifying model in which subsets of TNF family ligands distinguish the competitive niches for maintenance of CD4 versus CD8 T cell memory. Understanding the unique 'memory niches' defined by TNF family ligand expression will provide new insights into the mechanisms of memory T cell maintenance.

A critical role for TNF receptor-associated factor 1 and Bim down-regulation in CD8 memory T cell survival

The mechanisms that allow the maintenance of immunological memory remain incompletely defined. Here we report that tumor necrosis factor receptor (TNFR)-associated factor (TRAF) 1, a protein recruited in response to several costimulatory TNFR family members, is required for maximal CD8 T cell responses to influenza virus in mice. Decreased recovery of CD8 T cells in vivo occurred under conditions where cell division was unimpaired. In vitro, TRAF1-deficient, antigen-activated T cells accumulated higher levels of the proapoptotic BH3-only family member Bim, particularly the most toxic isoform, Bim(S). In the presence of excess IL-15, memory phenotype T cells with similar surface phenotype and comparable levels of Bcl-2 family members could be generated from WT or TRAF1-deficient T cell receptor transgenic OT-I T cells. However, when the memory CD8 T cells were allowed to compete for survival signals in the absence of antigen in vivo, the TRAF1-deficient T cells showed decreased recovery compared with TRAF1-sufficient T cells. This defect in T cell recovery in vivo was alleviated by introduction of siRNA to down-modulate Bim in TRAF1-deficient memory T cells. These studies identify the TRAF1 signaling axis and Bim down-regulation as critical for CD8 memory T cell survival in vivo.

Reductions in Stress and Depressive Symptoms in Mothers of Substance-Exposed Infants, Participating in a Psychosocial Program

OBJECTIVE

Depression profoundly impairs psychosocial functioning. Depression can have disruptive effects on a person's family, with significant impact on the psychosocial development of the children. Recent research suggests that a mother's depressive symptoms may increase parenting stress and that parenting stress may, in turn, increase depressive symptoms, with a possible negative cycle to this process. Little is known about how these two factors interact in drug-involved mothers. This study examines how the NEW CONNECTIONS intervention (a parental education and support program for drug-involved parents) acts on parental stress and symptoms of depression.

METHODS

The study site was the NEW CONNECTIONS Infant Intervention Program. The Beck Depression Inventory-II (BDI-II) and the Parenting Stress Index (PSI) were administered to drug- and alcohol-involved mothers (N = 120) at baseline and after the intervention (Week 12).

RESULTS

Four of the seven PSI domains of parenting stress showed a significant reduction (Demandingness, Competence, Isolation, and Role Restriction). Changes in four domains were significantly correlated with reductions in depressive symptoms (Competence, Isolation, Attachment, and Role Restriction). There was a significant reduction in depressive symptoms as measured by the BDI-II.

CONCLUSION

Reduction in some aspects of parenting stress is associated with reduction in depressive symptoms in mothers of substance-exposed infants who participated in the NEW CONNECTIONS psychosocial intervention targeting the parent-child relationship.

Treatment of substance abuse during pregnancy and infant outcome

The objective of this study is to analyze the effects of residential substance abuse treatment on pregnancy outcome among gravidas in a gender-specific program. All clients (cases) who entered a residential substance abuse program for pregnant and postpartum women were eligible for inclusion in the study (n=95). Only those who were in treatment at the time of delivery were included in the present analysis (n=57). Two comparison groups were used: (1) substance abusers who received no treatment during pregnancy (positive control group) and (2) pregnant women who were not substance abusers (negative control group). Cases were matched to controls on ethnicity (negative and positive controls) and drug of choice (positive controls only). Medical records were reviewed and abstracted for cases and controls. The primary drug of choice was cocaine for 56% of clients in the study, heroin 15.8%, and alcohol 10.8%. Average length of time in treatment before delivery was 11.7 weeks. The frequency of pregnancy complications allowing treatment and position controls was significantly higher than the negative control group (p<0.0001). The frequency of perinatal infant complications was increased among treatment group infants (p<0.0001). Two infants in the treatment group were positive for a substance of abuse at birth. In the treatment versus positive control group, mean birth weight (BW) was 3227 versus 2800 g (p<0.01), estimated gestational age (EGA) was 38.9 versus 39 weeks, average head circumference (FOC) was 33.8 versus 32.5 cm (p<0.05), and mean birth length (BLT) was 48.7 cm versus 46.9 (p<0.05). No significant differences were found between treatment and negative control groups. Maternal syphilis was increased in frequency in the positive control group compared with the negative control group (p<0.07). Thirty-percent of mothers had sexually transmitted diseases (STDs) for which infants were at risk and treated prophylactically; no infant in the treatment group contracted a vertically transmitted STD. For every 10 weeks in treatment, BW was increased 340 g, EGA 1 week, FOC 0.8 cm, and BLT 1.8 cm. Thus, substance abuse treatment for pregnant women in the program increased fetal growth, which significantly decreased the risk for poor neonatal outcomes. Importantly, maternal and infant perinatal complications in the treatment group were increased in frequency compared with the two control groups. This may possibly have occurred because healthcare providers were not blinded to maternal treatment status.

Fostering a culture of prevention in a residency program through a continuous quality improvement project

This project explored the effect of a multifaceted quality improvement (QI) intervention at a university-based residency program clinic on the documented provision of preventive services. The intervention, based on the Put Prevention Into Practice program and standard QI techniques, consisted of patient self-administered Health Risk Profiles (HRPs) and a monthly educational curriculum for patients, staff, and providers. Documentation of preventive services in patient charts was measured using a repeated cross-sectional sampling design before and after the 1-year intervention period. Documentation of 8 of 19 preventive services under examination increased significantly (P < .05). Measurements of the intervention, including use of the HRPs and the educational curriculum, revealed little association with the observed improvements. Although the intervention was associated with improved documentation of clinical preventive services, specific elements of the intervention were underused. The authors postulate that the QI process fostered a culture change in the clinic that affected prevention activities. Whether the increased documentation of services reflected an increase in the actual provision of services and whether this increase is clinically significant require further study.

Developing and evaluating ambulatory care: problem-based learning cases

Medical educators have raised concerns about the quality of teaching and learning in busy ambulatory care settings. Problem-based learning (PBL), which allows students to learn to diagnose and manage common ambulatory care problems as they discuss patients away from the clinical setting, is one possible solution for addressing these concerns. This article describes a process for developing realistic and well-written PBL cases for an ambulatory care clerkship. The process details specific steps for writing and evaluating cases to ensure they contain relevant learning issues students often encounter in outpatient training sites. Faculty at other institutions can adapt this process to develop and evaluate PBL cases reflecting the common presenting problems and patient issues at their sites.

Patient and physician explanatory models for acute bronchitis

OBJECTIVES

Our goals were to develop explanatory models to better understand how physicians diagnose and treat acute bronchitis; to describe patient expectations and needs when experiencing an episode of acute bronchitis; and to enhance communication between physician and patient.

STUDY DESIGN

We used qualitative, semi-structured, in-depth interviews to generate patient and physician explanatory models.

POPULATION

We had a purposeful, homogeneous sample of 30 family physicians and 30 adult patients.

OUTCOMES MEASURED

Our multidisciplinary team of investigators used an editing style of analysis to develop patient and physician explanatory models based on the following topics: (1) what caused my illness/etiology, (2) what symptoms I had/onset of symptoms, (3) what my sickness did to me/pathophysiology, (4) how severe is my sickness/course of illness, and (5) what kind of treatment should I receive/treatment.

RESULTS

We found that patient and physician models were congruous for symptoms of acute bronchitis and incongruous for etiology and course of illness. Models were congruous for treatment, although for different reasons.

CONCLUSIONS

Patients may have a very vague understanding of the process of infection and the difference between bacteria and viruses. Compounding this confusion is frequent miscommunication from physicians regarding the clinical course of untreated illness. These factors and non-communicated expectations from patients and fear of missing something on the part of physicians contribute to the decision to treat with antibiotics.

Peripartum cocaine use and adverse pregnancy outcome

The objective of the study was to analyze possible adverse effects of peripartum cocaine use on maternal and fetal outcomes. Informed consent was given by 720 (97%) of 740 women who delivered consecutively at a large urban public hospital to test an umbilical cord blood sample for the presence of non-medically administered drugs of abuse and alcohol and to be interviewed for the study. Samples were tested for the presence of a cocaine metabolite (benzoylecgonine-BZE) by radioimmunoassay. The presence of other substances of abuse (alcohol, methamphetamine, opiates) resulted in exclusion from the sample of 143 subjects. Thus, in this cohort analysis, drug-free controls (N = 469) were compared to those positive for cocaine only (N = 108). Peripartum exposure to cocaine only, and no other substances of abuse, was associated with an increased frequency of abruptio placentae (1.9% vs 0% for control, P < 0.004), thick meconium stained amniotic fluid (3.9% vs 0.7% for controls, P < 0.006), premature rupture of membranes (P < 0.02), genitourinary anomalies (OR = 3.6, P < 0.05), abdominal wall defects (OR = 4.4, P < 0.01) and increased frequency of low birth weight (OR = 2.0, P < 0.02). These are important findings because previous studies have been complicated by the confounding effects of other substances of abuse. Am. J. Hum. Biol. 11:598-602, 1999. Copyright 1999 Wiley-Liss, Inc.

Implementing problem-based learning in a family medicine clerkship

BACKGROUND AND OBJECTIVES

Problem-based learning (PBL) has been implemented in the curriculum of many medical schools, but limited information is available about the outcome of this learning technique. The educational intervention presented in this paper implemented a PBL learning component in our third-year family medicine clerkship and measured the outcomes of this curricular change.

METHODS

One third of the curricular time devoted to didactic teaching in our family medicine clerkship was replaced with PBL activities. Simulated cases were developed and presented to students who, with the aid of faculty facilitators, studied the cases, gathered information about the cases, and developed diagnostic and management plans for the cases. The outcome of the intervention was measured by a) comparing students' scores on the National Board of Medical Examiners (NBME) family medicine clerkship examination to scores achieved by students in the year before PBL was introduced and b) students' evaluations of the relevance and success of PBL in the clerkship curriculum.

RESULTS

Students' NBME clerkship examination scores increased from a mean of 66 the year before PBL began to 73 after PBL was implemented. More than 80% of students reported that PBL was a good way to learn family medicine, and 85% reported that the PBL technique provided sufficient information to formulate learning issues.

CONCLUSIONS

PBL can be introduced into a third-year family medicine clerkship curriculum with general acceptance by students. Students rated the technique highly, and their examination scores improved.

Verifying the curriculum of a family medicine clerkship

The learning experience during a medical school clinical rotation is largely shaped by students' patient encounters. This paper reports on how a log system for recording these encounters can be used for course planning and evaluation. Over the past 5 years, 960 third-year students completed log forms based on their clinical encounters during a required 4-week family medicine clerkship at UT Southwestern. These forms were then optically scanned and the information entered into a computerized database. Log form data revealed that the most common medical problems encountered by students in their ambulatory settings were similar to those reported in the general family practice literature. There was a great deal of consistency in the types of encounters from year to year. The data also showed some differences among clerkship sites in terms of patient demographics and the most frequently reported diagnoses. Information generated from student log forms has been used by the clerkship faculty to determine required readings, prioritize didactic topics and other teaching, adjust curriculum content, prepare support materials and develop examinations. Given the utility of the information obtained and the ease of use of optical mark encounter sheets, we recommend this system for other clerkships.

Treatment of acute bronchitis in adults. A national survey of family physicians

BACKGROUND

The purpose of this study was to determine how family physicians in the United States treat acute bronchitis in an otherwise healthy adult.

METHODS

A 33-item questionnaire on the diagnosis and treatment of acute bronchitis was mailed to a random sample of 500 physicians who are members of the American Board of Family Practice.

RESULTS

Thirty-two of the 500 sampled physicians could not be located by mail; 265 of those who received the questionnaire responded. The response rate was 57% (265/468). Sixty-three percent of responding physicians indicated that antibiotics are their first choice of treatment for the otherwise healthy, nonsmoking adult with acute bronchitis. The decision to use antibiotics as the first choice of treatment did not vary by physician's sex, age, years in practice, practice location, practice type, or percentage of HMO patients. Only 6% of responding physicians reported using beta 2 agonist bronchodilators as their first choice of treatment. Physicians in this study stated that they prescribe an antibiotic 75% of the time in treating nonsmoking patients with acute bronchitis (first choice or otherwise). If the patient is a smoker, physicians reported that they prescribe antibiotics 90% of the time (F = 110.25; df = 1; P > .0001). Physicians reported that for patients who smoke it takes longer for coughs to totally resolve and longer for them to return to a normal activity level than for nonsmokers.

CONCLUSIONS

Family physicians report that antibiotics are their most common treatment for acute bronchitis in the otherwise healthy adult. Previous clinical trials have shown only marginal improvement in symptoms when patients with this condition are treated with an antibiotic. With antibiotic resistance emerging as a major global health problem, it is essential that other methods of treatment be evaluated.

Diagnosis of acute bronchitis in adults: a national survey of family physicians

BACKGROUND

The purpose of this study was to determine how family physicians in the United States diagnose acute bronchitis in otherwise healthy adults.

METHODS

A 33-item questionnaire on the diagnosis and treatment of acute bronchitis was mailed to a random sample of 500 physicians who are members of the American Board of Family Practice.

RESULTS

Two hundred sixty-five physicians responded. Of those who did not respond, 32 could not be located. Of those who did respond, 10 were either retired or were practicing in another specialty. The net response rate was 56% (255/458). Responding physicians stated that character of cough and sputum production are the most important items used in diagnosing acute bronchitis. Fifty-eight percent indicated that the cough should be productive, and 60% stated that the sputum should be purulent. Seventy-two percent of respondents did not feel that wheezing or rhonchi need to be present. Younger physicians and those who selected antibiotics as their first treatment choice were more likely to define acute bronchitis as the presence of a productive cough with purulent sputum (P < .05). Physicians from an academic setting were more likely to define acute bronchitis as a productive cough (P < .05). Thirty-six percent of physicians from practices serving populations with > or = 60% managed care patients included wheezing or rhonchi in the definition of acute bronchitis, compared with 26% of all others (P < .05).

CONCLUSIONS

Variations in the diagnosis of acute bronchitis in otherwise healthy adults can be attributed to physician age, treatment choice, and practice setting. A significant number of family physicians did not require a productive cough as part of the diagnostic criteria for acute bronchitis. This finding needs to be considered in studies evaluating treatment. Additional qualitative studies are necessary to identify other factors involved in diagnosing acute bronchitis.

Risk of chromosomal abnormalities, with emphasis on live-born offspring of young mothers

In a large public urban hospital obstetrics service with > 123,000 deliveries in a 10-year period (1980-89), the frequencies (0.12%) of any type of chromosomal abnormality and of trisomy syndromes were analyzed for maternal age-related risk, by logistic regression. Focusing on very young gravidas, we found that in the study period there were 9,332 births (7.5% of all deliveries) to mothers < or = 16 years old. Estimated risks of chromosomal abnormalities among offspring associated with very young maternal age (9-16 years) were similar to those age-associated risks of mothers 20-29 years old. Risks of chromosomal abnormalities increase with advancing maternal age and are independent of ethnicity.

Computerized performance support systems: applications in a family practice clerkship

This article describes a computerized performance support system, the Clerkship Learning Expert and Resource Consultant (CLERC), developed to improve the quality and consistency of learning available to medical students in a third-year family practice clerkship. CLERC is an integrated computer system with an interactive knowledge base, software applications, literature search capabilities, and clinical diagnostic software programs. Medical students enrolled in a third-year family practice clerkship use CLERC to access up-to-date clinical information and to complete clerkship assignments.

Reliability of birth certificate reporting of congenital anomalies

Birth certificates comprise an important source of data on the prevalence of genetic conditions and for monitoring possible teratogens in the population. Investigators have found wide variability (12 to 100%) in the accuracy of reporting. In a large public hospital, of those congenital anomalies detected at birth, only 5.4% were recorded on the birth certificate. This is one of the lowest rates ever reported. An underreporting correction factor may be applied if congenital anomalies are distributed randomly with respect to reporting status, and the rate of reporting is sufficient to comprise a valid sample for estimating a correction factor (that is, 20% or more reported). In this study, factors such as numbers or types of anomalies, race, infant birthweight, or estimated gestational age did not significantly influence the rate of birth certificate reporting. Thus, our data satisfied the first but not the second criterion for derivation of a correction factor. In conducting epidemiologic studies, birth certificate data should be used with: (1) great caution; (2) a system of validation with the medical record to estimate the degree of underreporting and to derive a correction factor; and (3) a priori knowledge that underreporting of congenital anomalies on this document is highly prevalent.

Is hyperthermia teratogenic in the human?

Maternal hyperthermia during embryogenesis has been postulated to cause a variety of major congenital anomalies in exposed offspring. Although the literature regarding human exposures is not conclusive, studies using animal models support the contention that major structural anomalies may be produced. In the present study, pregnancy outcome of a cohort of women who reported having a temperature of 101 degrees F or higher for 24 hours or more during the first trimester was compared to a control group of women (matched on last menstrual period, parity, and age) who denied having a fever. A statistically significant increased frequency of a specific type of congenital anomaly, abdominal wall defects, was found in offspring whose mothers had sustained high temperatures during embryogenesis. Although an increased risk of this type of congenital anomaly is not consistent with previous epidemiologic studies, similar defects of this organ system have been reported in offspring of pregnant nonhuman primates (monkeys) and rodents (guinea pigs) who experienced hyperthermia during pregnancy.

HIV prevalence in pregnant intravenous drug users in Dallas, Texas

Information available regarding the prevalence of human immunodeficiency virus (HIV) in pregnant women indicates that the primary risk factor for infection is intravenous drug use. At Parkland Memorial Hospital in Dallas, Texas, approximately 4.7% of pregnant women reported using intravenous drugs. The estimated prevalence of HIV infection among pregnant intravenous drug users at this hospital was 3.3%. This is similar to the HIV infection rates reported for nonpregnant parenteral drug-using populations in other areas of the southwestern United States, suggesting that there may be a lower rate of endemic infection in this region of the country.

Brain growth among fetuses exposed to cocaine in utero: asymmetrical growth retardation

Fetal growth retardation may be associated with maternal cocaine use during pregnancy. The pattern of fetal growth retardation was analyzed in infants born to 80 women who used cocaine, but not alcohol, during pregnancy, and in two comparison groups: 100 infants born to mothers who used neither alcohol nor cocaine during pregnancy and 67 infants whose mothers used alcohol but not cocaine during pregnancy. There were statistically significant differences in head size between the unexposed and cocaine-exposed infants (P less than .001). Notably, head circumference was reduced proportionately more than birth weight in cocaine-exposed infants, a pattern similar to that observed in alcohol-exposed infants. Alcohol- and cocaine-exposed infants were not statistically different in head circumference. We conclude that brain growth of cocaine-exposed infants is similar to that reported for alcohol-exposed infants, and that cocaine-exposed infants may be characterized as having asymmetrical growth retardation.