Effect of chloroquine and leupeptin on intracellular accumulation of amyloid-beta (A beta) 1-42 peptide in a murine N9 microglial cell line

Murine N9 microglia accumulated A beta from media containing 0.67 microM A beta within 6 h. In N9 and in primary rat microglia, chloroquine, which disrupts lysosomal pH, increased A beta-induced accumulation of A beta, particularly A beta1-42. Leupeptin similarly enhanced A beta accumulation. The scavenger receptor antagonist fucoidan did not affect acute chloroquine-dependent A beta1-42 accumulation, demonstrating uptake of non-aggregated A beta. After prolonged incubations, chloroquine enhanced A beta multimer (8-12 kDa) accumulation, an effect inhibited by fucoidan. Disruptions of the lysosomal system enhance A beta and its multimer formation. Despite negligible effects of fucoidan on initial A beta uptake, chronic exposure inhibits multimer accumulation, demonstrating a role for scavenger receptor in multimer accumulation.

Acute intentional iron overdose in pregnancy

BACKGROUND

Although iron is the second most common overdose agent in pregnancy, the obstetric literature does not reflect current management of this emergency.

CASE

A 27-year-old woman, para 0-3-4-3, at 27 weeks' gestation ingested 24 mg/kg of elemental iron in a suicide attempt. Therapy with crystalloid hydration, gastric lavage, and intravenous deferoxamine chelation treated the overdose without maternal or fetal complications.

CONCLUSION

Pregnancy should not alter therapy for acute iron overdose. Deferoxamine administered in the third trimester is not associated with perinatal complications and is potentially life saving.

Sexual behavior and pregnancy outcome in HIV-infected women. Canadian Women's HIV Study Group

Sexual behavior and pregnancy outcome data for 392 HIV-infected women were analyzed. During the 6 months before study entry, 71.2% (279 of 392 women) were sexually active. In multivariate regression, women with baseline CD4+ > or = 200/microl were more likely than women with CD4+ < 200/microl to be sexually active (adjusted odds ratio [OR] = 1.75; 95% confidence interval [CI], 1.06-2.88; p = .03). Consistent condom use was reported with 58.4% (149 of 255) of steady male partners and 65.7% (23 of 35) of casual partners. Overall, 90.3% of 279 sexually active women were using contraception. Among women aged between 15 and 44 years (n = 320), the incidence of pregnancy in the year before HIV diagnosis was 27.5 per 100 person-years (PY) (95% CI, 22.1-33.9) compared with 8.3/100 PY (95% CI, 6.8-10.2) in the time since HIV diagnosis (p < .001). The incidence of therapeutic termination of pregnancies conceived in the 20 weeks before HIV diagnosis (10.6/100 PY) was more than triple that after diagnosis (3.1/100 PY; p = .001). After publication of results of zidovudine prophylaxis of mother-to-child transmission, pregnancy rates did not increase, but the incidence of therapeutic abortion dropped from 4.3/100 PY to 1.4/100 PY (p = .009). Knowledge of sexual behavior, including pregnancy frequency and outcome, can assist in tailoring counseling for HIV-infected women concerning sexual and reproductive health.

Socioeconomic geographical links to human immunodeficiency virus seroprevalence among childbearing women in Montreal, 1989-1993

BACKGROUND

To describe the socioeconomic profiles of geographical areas on Montreal Island in which human immunodeficiency virus (HIV) seropositive women delivering live births between 1989 and 1993 reside.

METHODS

Leftover dried blood spot filter paper specimens collected from newborns were irretrievably unlinked from identifying information prior to testing. Seroprevalence estimates were calculated based on Western blot confirmed positive samples. Using data from the Canadian census, Revenue Canada, and provincial birth records, the socioeconomic characteristics of postal zones in which seropositive mothers reside were described.

RESULTS

Montreal Island had an overall 5-year HIV seroprevalence rate estimate of 16.6 (95% CI: 14.1-19.3) per 10000 childbearing women. Areas in which at least one seropositive woman gave birth had lower mean infant birthweights and higher percentages of single mothers and single-parent families. The HIV-positive neonatal blood specimens were more likely to originate from areas where a higher proportion of residents reported less education, greater unemployment, and lower income.

CONCLUSIONS

Higher HIV infection rates were found among childbearing women from lower socioeconomic areas of Montreal. Increased understanding of the relationship between socioeconomic status and HIV acquisition and transmission is required to inform the development of targeted HIV prevention programmes.

Mid-trimester ultrasound diagnosis of isolated talipes equinovarus: accuracy and outcome for infants

Seventeen fetuses were diagnosed with isolated congenital talipes equinovarus (CTEV) on mid-trimester ultrasound at the Royal Women's Hospital, Melbourne, between January, 1992 and December 1995. Sixteen of the 17 cases had an amniocentesis performed and all karyotypes were normal. The remaining case was phenotypically normal, except for a clubfoot. None of the pregnancies was complicated by any of the recognized intrauterine environmental causes of CTEV. Four of the babies were delivered prematurely and all survived the neonatal period. Six (35%) infants did not have CTEV at birth, although 2 had postural varus feet. Nine of the 11 infants who did have CTEV at birth were treated within days of birth with plaster of Paris for periods of 6 to 12 weeks. Two infants required no further treatment, 5 required orthotics and 2 required surgery. The other 2 infants with CTEV at birth were treated with orthotics at 8 weeks of age. All infants were considered to have an excellent result at the 2 year follow-up. Seven (41%) of the prospective parents received antenatal counselling by an orthopaedic surgeon and the lack of study on outcome following an ultrasound diagnosis of CTEV was the impetus for our work.

Use of plasma concentrations of 13,14-dihydro,15-keto-PGF2 alpha (PGFM) in the diagnosis of sub-clinical endometritis and its relationship to fertility in the postpartum dairy cow

The objective of this study was to determine the value of using plasma concentrations of PGFM to diagnose subclinical endometritis in the dairy cow, and its relationship to subsequent fertility. A total of 274 cows between 24 to 29 d post partum was divided into 4 groups on the basis of clinical features of the uterus and ovary. Cows in Group 1 (n = 74) had a normal, involuting uterus and a CL on the ovary; cows in Group 2 (n = 51) had a normal, involuting uterus but no CL on the ovary; cows in Group 3 (n = 83) did not have a normal, involuting uterus but had a CL on the ovary; and cows in Group 4 (n = 66) did not have a normal, involuting uterus or a CL on the ovary. A blood sample was obtained from each cow on the day they were placed on the study, and plasma concentrations of PGFM and P4 were determined using RIA. Cows were artificially inseminated (AI) at the first observed estrus after Day 60 post partum, and pregnancy was determined by palpation of the uterus per rectum between 45 and 50 d postAI. Reproductive responses evaluated were conception rate to first service, days open, and percentage of cows pregnant by 90, 120, 150 and 180 d post partum. Data were analyzed using GLM procedures of SAS and a 2 x 2 factorial with contrast procedures. Polynomial regression analysis was used to determine the shape of the PGFM, P4 and fertility curves. There was no difference among mean PGFM concentrations of cows in each group. The rate of decline of plasma PGFM concentrations was lower in cows with an abnormal uterus and a CL on the ovary compared with those without a CL. A lower percentage of cows with abnormal uteri was pregnant by 90 d post partum compared with cows with normal uteri. From the results of this study, it was concluded that plasma PGFM concentrations between Days 24 to 29 post partum were not effective in identifying cows with subclinical endometritis.

T cell development in mice lacking all T cell receptor zeta family members (Zeta, eta, and FcepsilonRIgamma)

The zeta family includes zeta, eta, and FcepsilonRIgamma (Fcgamma). Dimers of the zeta family proteins function as signal transducing subunits of the T cell antigen receptor (TCR), the pre-TCR, and a subset of Fc receptors. In mice lacking zeta/eta chains, T cell development is impaired, yet low numbers of CD4+ and CD8+ T cells develop. This finding suggests either that pre-TCR and TCR complexes lacking a zeta family dimer can promote T cell maturation, or that in the absence of zeta/eta, Fcgamma serves as a subunit in TCR complexes. To elucidate the role of zeta family dimers in T cell development, we generated mice lacking expression of all of these proteins and compared their phenotype to mice lacking only zeta/eta or Fcgamma. The data reveal that surface complexes that are expressed in the absence of zeta family dimers are capable of transducing signals required for alpha/beta-T cell development. Strikingly, T cells generated in both zeta/eta-/- and zeta/eta-/--Fcgamma-/- mice exhibit a memory phenotype and elaborate interferon gamma. Finally, examination of different T cell populations reveals that zeta/eta and Fcgamma have distinct expression patterns that correlate with their thymus dependency. A possible function for the differential expression of zeta family proteins may be to impart distinctive signaling properties to TCR complexes expressed on specific T cell populations.

Mice deficient in nuclear factor (NF)-kappa B/p52 present with defects in humoral responses, germinal center reactions, and splenic microarchitecture

p52 is a subunit of nuclear factor (NF)-kappa B transcription factors, most closely related to p50. Previously, we have shown that p52, but not p50 homodimers can form transactivating complexes when associated with Bcl-3, an unusual member of the I kappa B family. To determine nonredundant physiologic roles of p52, we generated mice deficient in p52. Null mutant mice were impaired in their ability to generate antibodies to T-dependent antigens, consistent with an absence of B cell follicles and follicular dendritic cell networks in secondary lymphoid organs, and an inability to form germinal centers. Furthermore, the splenic marginal zone was disrupted. These phenotypes are largely overlapping with those observed in Bcl-3 knockout animals, but distinct from those of p50 knockouts, supporting the notion of a physiologically relevant complex of p52 homodimers and Bcl-3. Adoptive transfer experiments further suggest that such a complex may be critical in accessory cell functions during antigen-specific immune reactions. Possible roles of p52 and Bcl-3 are discussed that may underlie the oncogenic potential of these proteins, as evidenced by recurrent chromosomal translocations of their genes in lymphoid tumors.

Requirement for NF-kappaB in osteoclast and B-cell development

NF-kappaB is a family of related, dimeric transcription factors that are readily activated in cells by signals associated with stress or pathogens. These factors are critical to host defense, as demonstrated previously with mice deficient in individual subunits of NF-kappaB. We have generated mice deficient in both the p50 and p52 subunits of NF-kappaB to reveal critical functions that may be shared by these two highly homologous proteins. We now demonstrate that unlike the respective single knockout mice, the p50/p52 double knockout mice fail to generate mature osteoclasts and B cells, apparently because of defects that track with these lineages in adoptive transfer experiments. Furthermore, these mice present markedly impaired thymic and splenic architectures and impaired macrophage functions. The blocks in osteoclast and B-cell maturation were unexpected. Lack of mature osteoclasts caused severe osteopetrosis, a family of diseases characterized by impaired osteoclastic bone resorption. These findings now establish critical roles for NF-kappaB in development and expand its repertoire of roles in the physiology of differentiated hematopoietic cells.

Absence of Porphyromonas asaccharolytica, Bacteroides fragilis and Chlamydia pneumoniae in human subgingival plaque

Little is known about the presence of common medical pathogens in the human oral cavity. Using a 16S rRNA-based PCR identification method, this study determined the occurrence of Porphyromonas asaccharolytica, Bacteroides fragilis and Chlamydia pneumoniae in subgingival plaque from 50 adults with advanced periodontitis. Each patient contributed samples from 3 deep periodontal pockets collected by paper points. The PCR primers were for P. asaccharolytica 5'-CTC TAG CTA GAG TGT ACT GG-3' and 5'-ATA GGG TTT ATA GAT TAG CTC TCT-3', for B. fragilis 5'-AAT GAT TCC GCA TGG TTT CAT TA-3' and 5'-GCG GTG ATT GCT CAC TGA CA-3', and for C. pneumoniae 5'- TGA CAA CTG TAG AAA TAC AGC-3' and 5'-CGC CTC TCT CCT ATA AAT-3'. The primers yielded a single amplicon with the respective reference strains and produced no amplicon with colonies of 25 groups of oral organisms. None of the three test species were detected in any of the 50 pooled subgingival samples tested. P. asaccharyolytica, B. fragilis and C. pneumoniae do not seem to be part of the periodontopathic microbiota in humans.

Childhood hearing impairment: processing dependencies in multidimensional speech perception for an auditory level of analysis

OBJECTIVE

Our purpose was to determine whether the influence of childhood hearing impairment (HI) on multidimensional speech processing is a purely linguistic effect or whether childhood HI also affects the processing of speech dimensions representing an auditory level of analysis.

DESIGN

The processing dependencies characterizing the two dimensions of talker-gender and spatial location were studied in 40 children with HI and in two normal-hearing (NH) comparison groups representing similar chronological ages (N = 30) or similar vocabulary skills (N = 70). The processing interactions were assessed with a speeded selective-attention task requiring listeners to attend selectively to the gender of the talker and to ignore the spatial location and vice versa. The logic is that performance for the target dimension will not be affected by what is happening on the nontarget dimension if the dimensions are processed independently. On the other hand, if the dimensions are not processed independently, listeners will not be able to attend selectively and performance for the relevant dimension will be affected by what is happening on the irrelevant dimension. In the latter case, results may be analyzed in terms of Garner interference (the effect on performance of irrelevant variability in the to-be-ignored dimension) (Garner, 1974a) and Simon interference (the effect on performance of an irrelevant spatial source) (Simon, 1990).

RESULTS

Overall results in all listeners, those with NH or HI, showed significant interference when the participants were attending to the gender of the talker and ignoring spatial location and vice versa. The talker-gender and spatial-location dimensions of speech were not processed independently by these children. When the processing interactions were compared between the NH and HI groups, the presence of childhood HI as a general rule significantly diminished the degree of interference from spatial location. The degree of interference from the gender of the talker, on the other hand, remained normal in the presence of childhood HI. All listeners seemed stimulus bound by the gender of the talker. The degree of Garner interference did not show age-related or degree of loss-related change. The degree of Simon interference showed significant change as a function of age in the children with mild-moderate HI, but not in the children with severe HI. The developmental function for Simon interference in the children with mild-moderate HI was delayed to a degree that corresponded to the duration of the auditory deprivation.

CONCLUSIONS

The overall pattern of results indicates that the influence of childhood HI on multidimensional speech processing is not a purely linguistic effect.

In vitro- and ex vivo-derived cytolytic leukocytes from granzyme A x B double knockout mice are defective in granule-mediated apoptosis but not lysis of target cells

Granzyme (gzm) A and gzmB have been implicated in Fas-independent nucleolytic and cytolytic processes exerted by cytotoxic T (Tc) cells, but the underlying mechanism(s) remains unclear. In this study, we compare the potential of Tc and natural killer (NK) cells of mice deficient in both gzmA and B (gzmAxB-/-) with those from single knockout mice deficient in gzmA (-/-), gzmB (-/-), or perforin (-/-) to induce nuclear damage and lysis in target cells. With the exception of perforin-/-, all in vitro- and ex vivo-derived Tc and NK cell populations from the mutant strains induced 51Cr-release in target cells at levels and with kinetics similar to those of normal mice. This contrasts with their capacity to induce apoptotic nuclear damage in target cells. In gzmAxB-/- mice, Tc/NK-mediated target cell DNA fragmentation was not observed, even after extended incubation periods (10 h), but was normal in gzmA-deficient and only impaired in gzmB-deficient mice in short-term (2-4 h), but not long-term (4-10 h), nucleolytic assays. This suggests that gzmA and B are critical for Tc/NK granule- mediated nucleolysis, with gzmB being the main contributor, while target cell lysis is due solely to perforin and independent of both proteases.

Phorbol esters and SDF-1 induce rapid endocytosis and down modulation of the chemokine receptor CXCR4

The chemokine receptor CXCR4 is required, together with CD4, for entry by some isolates of HIV-1, particularly those that emerge late in infection. The use of CXCR4 by these viruses likely has profound effects on viral host range and correlates with the evolution of immunodeficiency. Stromal cell-derived factor-1 (SDF-1), the ligand for CXCR4, can inhibit infection by CXCR4-dependent viruses. To understand the mechanism of this inhibition, we used a monoclonal antibody that is specific for CXCR4 to analyze the effects of phorbol esters and SDF-1 on surface expression of CXCR4. On human T cell lines SupT1 and BC7, CXCR4 undergoes slow constitutive internalization (1.0% of the cell surface pool/min). Addition of phorbol esters increased this endocytosis rate >6-fold and reduced cell surface CXCR4 expression by 60 to 90% over 120 min. CXCR4 was internalized through coated pits and coated vesicles and subsequently localized in endosomal compartments from where it could recycle to the cell surface after removal of the phorbol ester. SDF-1 also induced the rapid down modulation (half time approximately 5 min) of CXCR4. Using mink lung epithelial cells expressing CXCR4 and a COOH-terminal deletion mutant of CXCR4, we found that an intact cytoplasmic COOH-terminal domain was required for both PMA and ligand-induced CXCR4 endocytosis. However, experiments using inhibitors of protein kinase C indicated that SDF-1 and phorbol esters trigger down modulation through different cellular mechanisms. SDF-1 inhibited HIV-1 infection of mink cells expressing CD4 and CXCR4. The inhibition of infection was less efficient for CXCR4 lacking the COOH-terminal domain, suggesting at least in part that SDF-1 inhibition of virus infection was mediated through ligand-induced internalization of CXCR4. Significantly, ligand induced internalization of CXCR4 but not CD4, suggesting that CXCR4 and CD4 do not normally physically interact on the cell surface. Together these studies indicate that endocytosis can regulate the cell-surface expression of CXCR4 and that SDF-1-mediated down regulation of cell-surface coreceptor expression contributes to chemokine-mediated inhibition of HIV infection.

Successful treatment of canine malignant histiocytosis with the human major histocompatibility complex nonrestricted cytotoxic T-cell line TALL-104

The human MHC nonrestricted cytotoxic T-cell line TALL-104 exerts potent antitumor effects in animal models with both induced and spontaneous cancers. The present report documents the ability of systemically delivered TALL-104 cells to induce durable clinical remissions in four of four dogs with malignant histiocytosis (MH). The animals received multiple i.v. injections of lethally irradiated (40 Gy) TALL-104 cells at a dose of 10(8) cells/kg, with (two dogs) or without (two dogs) cyclosporin A, followed by monthly boosts. No significant clinical or laboratory toxicities developed during cell therapy; interestingly, a strong correlation was found between the dogs' clinical and immunological responses. One dog with advanced disease (intrathoracic involvement) refractory to chemotherapy achieved a complete remission (CR) within 2 months of the first TALL-104 cell infusion. This dog died 14 months later of unrelated causes: histological analysis of its organs postmortem revealed no evidence of neoplasia, thus confirming the achievement of CR also at the pathological level. The other three dogs with MH that at diagnosis had multiple s.c. and cutaneous lesions and lymphadenopathy, but no visceral involvement, were treated with TALL-104 cells as single agent (no chemotherapy was administered). Two of these dogs achieved a CR soon after cell therapy, and the third dog had two long-lasting partial responses; CR in this dog was later achieved by combined administration of chemotherapy and cell therapy. None of the three dogs that received cell therapy at diagnosis developed visceral disease in the approximately 9-22 months of follow-up. The clinical responses experienced by all four MH cases to TALL-104 cell therapy suggest the high responsiveness of this canine tumor to these xenogeneic effectors and their therapeutic potential even in the most aggressive forms of the disease.

Hormone replacement therapy and the risk of breast lesions that predispose to cancer

To determine whether postmenopausal individuals being treated with hormone replacement therapy (HRT) have an increased risk for lesions that predispose to breast cancer, 156 women with benign breast lesions were retrospectively studied. Their ages ranged from 43 to 88. Each patient underwent a breast biopsy from 1991 to 1995. It was determined from chart review whether each of these patients had been treated with HRT. Fifty-seven of these patients had a biopsy finding that predisposed the patient to future breast cancer. The predisposing lesions included sclerosing adenosis, intraductal papilloma, and epithelial hyperplasia with atypia. Of these 57 patients, 36 (63%) were being treated with HRT. Only 30 of the 99 patients (30%) with nonproliferative lesions were treated with HRT (odds ratio, 3.9; P < 0.0005). On the basis of the results of this study, we believe that the use of HRT may promote lesions that predispose to cancer. This suggests that patients treated with HRT require vigilant surveillance by way of examination and mammography.

Fc epsilonRI gamma can support T cell development and function in mice lacking endogenous TCR zeta-chain

Fc epsilonRI gamma (Fc gamma) is a member of the zeta family of signal transducing molecules that function as components of both the TCR and Fc receptors (FcR). While the majority of thymocytes and T cells express TCRs containing zeta-chain homodimers, certain unique populations of T cells express TCRs that contain both zeta and Fc gamma. To examine the ability of Fc gamma to substitute for zeta-chain in T cell development and function, we introduced a transgene encoding Fc gamma into mice made genetically deficient for zeta-chain (zeta(e)-/-). Analysis of thymocyte development in zeta(e)-/-;Fc gamma Tg mice demonstrated that Fc gamma was able to support the maturation of both gammadelta TCR+ and alphabeta TCR+ T cells. However, positive selection of alphabeta TCR+ thymocytes was less efficient in zeta(e)-/-;Fc gamma Tg mice than in zeta(e)-/- mice reconstituted with zeta-chain. This difference may be due to the fact that Fc gamma contains a single immunoreceptor tyrosine-based activation motif (ITAM) whereas zeta-chain contains three ITAMs. Interestingly, the peripheral T cells that develop in zeta(e)-/- mice reconstituted with Fc gamma are functional and respond to TCR-specific stimuli. These data suggest that Fc gamma and zeta are interchangeable in their ability to mediate T cell development and function, however zeta-chain is more efficient at promoting positive selection and T cell maturation. The difference in efficiency between zeta and Fc gamma may be responsible in part for the unusual developmental and functional properties of T cells that constitutively express Fc gamma as a signaling component of their TCRs.

Fc epsilonRI gamma can support T cell development and function in mice lacking endogenous TCR zeta-chain

Fc epsilonRI gamma (Fc gamma) is a member of the zeta family of signal transducing molecules that function as components of both the TCR and Fc receptors (FcR). While the majority of thymocytes and T cells express TCRs containing zeta-chain homodimers, certain unique populations of T cells express TCRs that contain both zeta and Fc gamma. To examine the ability of Fc gamma to substitute for zeta-chain in T cell development and function, we introduced a transgene encoding Fc gamma into mice made genetically deficient for zeta-chain (zeta(e)-/-). Analysis of thymocyte development in zeta(e)-/-;Fc gamma Tg mice demonstrated that Fc gamma was able to support the maturation of both gammadelta TCR+ and alphabeta TCR+ T cells. However, positive selection of alphabeta TCR+ thymocytes was less efficient in zeta(e)-/-;Fc gamma Tg mice than in zeta(e)-/- mice reconstituted with zeta-chain. This difference may be due to the fact that Fc gamma contains a single immunoreceptor tyrosine-based activation motif (ITAM) whereas zeta-chain contains three ITAMs. Interestingly, the peripheral T cells that develop in zeta(e)-/- mice reconstituted with Fc gamma are functional and respond to TCR-specific stimuli. These data suggest that Fc gamma and zeta are interchangeable in their ability to mediate T cell development and function, however zeta-chain is more efficient at promoting positive selection and T cell maturation. The difference in efficiency between zeta and Fc gamma may be responsible in part for the unusual developmental and functional properties of T cells that constitutively express Fc gamma as a signaling component of their TCRs.

Sexuality in Montreal women living with HIV

The impact of learning a positive HIV test result on the sexuality of 161 women (47 injection drug users (IDU), 53 non-IDU women of Haitian or African origin (non-IDU-HA), and 61 non-IDU Caucasian women (non-IDU-C) was assessed using closed and open-ended questions. Self-reported CD4+ count correlated with any post-test (p = 0.001) and past month sexual activity (p = 0.007). After learning their HIV status, 110 women (68%) were sexually active, 48 (44%) of these within 1 month. After resuming sexual activity, 84% underwent a sexual adjustment period (median duration 8.5 months). IDU women were more likely to have frequent sex, be anorgasmic, and prefer sex less often. Consistent partner condom use was low in general (19% for IDU, 30% for non-IDU-HA, and 62% for non-IDU-C) and by partner type (new regular partner 58%, same regular partner 36%, casual partner 29%). Sexual satisfaction tended to decline post-test and then increase to higher than pre-test levels. Counselling focused on the safe and satisfying aspects of sex may assist women with HIV infection in sexual decision-making. Facilitating the access of IDU women with HIV infection to medically supervised drug provision and to detoxification and rehabilitation programmes can weaken the link between drug use and sex work.

Critical roles for the Bcl-3 oncoprotein in T cell-mediated immunity, splenic microarchitecture, and germinal center reactions

Chromosomal translocations of bcl-3 are associated with chronic B cell lymphocytic leukemias. Previously, we have shown that Bcl-3, a distinct member of the I kappa B family, may function as a positive regulator of NF-kappa B activity, although its physiologic roles remained unknown. To uncover these roles, we generated Bcl-3-deficient mice. Mutant mice, but not their littermate controls, succumb to T. gondii owing to failure to mount a protective T helper 1 immune response. Bcl-3-deficient mice are also impaired in germinal center reactions and T-dependent antibody responses to influenza virus. The results reveal critical roles for Bcl-3 in antigen-specific priming of T and B cells. Altered microarchitecture of secondary lymphoid organs in mutant mice, including partial loss of B cells, may underlie the immunologic defects. The implied role of Bcl-3 in maintaining B cells in wild-type mice may related to its oncogenic potential.

Role of the multiple T cell receptor (TCR)-zeta chain signaling motifs in selection of the T cell repertoire

Immature thymocytes undergo a selection process within the thymus based on their T cell antigen receptor (TCR) specificity that results either in their maturation into functionally competent, self-MHC-restricted T cells (positive selection) or their deletion (negative selection). The outcome of thymocyte selection is thought to be controlled by signals transduced by the TCR that vary in relation to the avidity of the TCR-ligand interaction. The TCR is composed of four distinct signal transducing subunits (CD3-gamma, -delta, -epsilon, and zeta) that contain either one (CD3-gamma, -delta, -epsilon) or three (-zeta) signaling motifs (ITAMs) within their intracytoplasmic domains. A possible function for multiple TCR ITAMs could be to amplify signals generated by the TCR during selection. To determine the importance of the multiple TCR-zeta chain ITAMs in thymocyte selection, transgenes encoding alpha/beta TCRs with known specificity were bred into mice in which zeta chains lacking one or more ITAMs had been genetically substituted for endogenous zeta. A direct relationship was observed between the number of zeta chain ITAMs within the TCR complex and the efficiency of both positive and negative selection. These results reveal a role for multiple TCR ITAMs in thymocyte selection and identify a function for TCR signal amplification in formation of the T cell repertoire.

Assessment of fetal well-being in methadone-maintained pregnancies: abnormal nonstress tests

OBJECTIVE

To investigate parameters of fetal well-being (characteristics of nonstress test, NST, and antepartum fetal heart rate, FHR, patterns) and selected neonatal outcomes in pregnant women on methadone maintenance.

STUDY DESIGN

A matched case-control study of methadone-treated women receiving prenatal and intrapartum care at a Bronx municipal hospital during 1992-1994. 102 NSTs obtained from 24 methadone-treated women after 35 weeks of pregnancy were compared to 96 NSTs from a control group (n = 24), matched for maternal age, parity, and gestational age. All NSTs were evaluated for general characteristics including time interval between initiation and achievement of reactive NST (2 accelerations > or = 15 bpm lasting for at least 15 s in a 20-min period), baseline, amplitude of fluctuation, frequency of fluctuation, accelerations and decelerations. The scoring system described by Lyons et al. was used for all NSTs. All nonreactive NSTs were followed with biophysical profile tests.

RESULTS

The frequency of nonreactive NSTs was significantly higher for methadone-maintained women compared to controls (19.6 vs. 4.2%; p < 0.01). The average length of time to achieve reactive NST was significantly (p = 0.0016) longer for the methadone-treated group when compared to controls (35.50 +/- 20.96 vs. 14.85 +/- 9.03 min). The total score (Lyons et al.) was significantly lower (p < 0.0007) for the methadone-treated group compared to controls. Mean birth weight, Apgar scores at 1 and 5 min, meconium, and umbilical cord artery pH were not significantly different for methadone-exposed neonates compared to controls.

CONCLUSION

Methadone-maintained pregnancies are significantly associated with a higher incidence of nonreactive NSTs, longer intervals to achieve reactive NSTs and lower NST scores compared to controls. This may reflect an altered response in fetal central nervous system neurotransmitters and changes in fetal behavior induced by methadone.