Aberrantly low STAT3 and STAT5 responses are associated with poor outcome and an inflammatory gene expression signature in pediatric acute myeloid leukemia

The relapse rate for children with acute myeloid leukemia is nearly 40% despite aggressive chemotherapy and often stem cell transplant. We sought to understand how environment-induced signaling responses are associated with clinical response to treatment. We previously reported that patients whose AML cells showed low G-CSF-induced STAT3 activation had inferior event-free survival compared to patients with stronger STAT3 responses. Here, we expanded the paradigm to evaluate multiple signaling parameters induced by a more physiological stimulus. We measured STAT3, STAT5 and ERK1/2 responses to G-CSF and to stromal cell-conditioned medium for 113 patients enrolled on COG trials AAML03P1 and AAML0531. Low inducible STAT3 activity was independently associated with inferior event-free survival in multivariate analyses. For inducible STAT5 activity, those with the lowest and highest responses had inferior event-free survival, compared to patients with intermediate STAT5 responses. Using existing RNA-sequencing data, we compared gene expression profiles for patients with low inducible STAT3/5 activation with those for patients with higher inducible STAT3/5 signaling. Genes encoding hematopoietic factors and mitochondrial respiratory chain subunits were overexpressed in the low STAT3/5 response groups, implicating inflammatory and metabolic pathways as potential mechanisms of chemotherapy resistance. We validated the prognostic relevance of individual genes from the low STAT3/5 response signature in a large independent cohort of pediatric AML patients. These findings provide novel insights into interactions between AML cells and the microenvironment that are associated with treatment failure and could be targeted for therapeutic interventions.

Soluble CD40L is associated with increased oxidative burst and neutrophil extracellular trap release in Behçet's disease

Background

Studies have suggested that soluble factors in plasma from patients with active (aBD) and inactive (iBD) Behçet’s disease (BD) stimulate neutrophil function. Soluble CD40 ligand (sCD40L) is an important mediator of inflammation in BD. Its expression and effect on neutrophil oxidative burst and neutrophil extracellular trap (NET) release have not been characterized. In this study, we sought to investigate the role of plasma and the CD40L pathway on NET release and the oxidative burst profile in patients with aBD and iBD.

Methods

Neutrophils and peripheral blood mononuclear cells (PBMCs) were obtained from patients with aBD (n = 30), patients with iBD (n = 31), and healthy control subjects (HCs; n = 30). sCD40L plasma concentration was determined in individual samples. A pool of plasma for each group was created. In some experiments, plasma pools were treated with recombinant CD40 (rhCD40-muIg) for sCD40L blockade. NET release and H₂O₂/O₂⁻ production were determined after stimulation with phorbol 12-myristate 13-acetate, sCD40L, or plasma pool. Flow cytometric analysis was performed to evaluate the expression of (1) CD40, Mac-1, and phosphorylated NF-κB p65 on neutrophils and monocytes and (2) CD40L on activated T cells and platelets. CD40L gene expression in PBMCs was determined by qRT-PCR.

Results

sCD40L plasma levels were significantly higher in patients with iBD (median 17,234, range 2346–19,279 pg/ml) and patients with aBD (median 18,289, range 413–19,883 pg/ml) than in HCs (median 47.5, range 33.7–26.7 pg/ml; p < 0.001). NET release was constitutively increased in BD compared with HC. NET release and H₂O₂/O₂⁻ were higher after stimulation with sCD40L or BD plasma and decreased after sCD40L blockade. Mac-1 expression was constitutively increased in neutrophils of patients with aBD (88.7 ± 13.2% of cells) and patients with iBD (89.2 ± 20.1% of cells) compared with HC (27.1 ± 18.8% of cells; p < 0.01). CD40 expression on phagocytes and CD40L expression on platelets were similar in the three groups. PBMCs as well as nonactivated and activated CD4⁺ T cells from patients with BD showed higher CD40L expression.

Conclusions

Plasma from patients with aBD exerts a stimulus on NET release and oxidative burst, probably induced by sCD40L.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-017-1443-5) contains supplementary material, which is available to authorized users.

Microchimeric cells in systemic lupus erythematosus: targets or innocent bystanders?

During pregnancy maternal and fetal cells commute back and forth leading to fetal microchimerism in the mother and maternal microchimerism in the child that can persist for years after the birth. Chimeric fetal and maternal cells can be hematopoietic or can differentiate into somatic cells in multiple organs, potentially acting as targets for ‘autoimmunity' and so have been implicated in the pathogenesis of autoimmune diseases that resemble graft-versus-host disease after stem cell transplantation. Fetal cells have been found in women with systemic lupus erythematosus, both in the blood and a target organ, the kidney, suggesting that they may be involved in pathogenesis. Future studies will address how the host immune system normally tolerates maternal and fetal cells or how the balance may change during autoimmunity.

Genetic association of CD247 (CD3ζ) with SLE in a large-scale multiethnic study

A classic T-cell phenotype in systemic lupus erythematosus (SLE) is the downregulation and replacement of the CD3ζ chain that alters T-cell receptor signaling. However, genetic associations with SLE in the human CD247 locus that encodes CD3ζ are not well established and require replication in independent cohorts. Our aim was therefore to examine, localize and validate CD247-SLE association in a large multiethnic population. We typed 44 contiguous CD247 single-nucleotide polymorphisms (SNPs) in 8922 SLE patients and 8077 controls from four ethnically distinct populations. The strongest associations were found in the Asian population (11 SNPs in intron 1, 4.99 × 10(-4) < P < 4.15 × 10(-2)), where we further identified a five-marker haplotype (rs12141731-rs2949655-rs16859085-rs12144621-rs858554; G-G-A-G-A; P(hap) = 2.12 × 10(-5)) that exceeded the most associated single SNP rs858554 (minor allele frequency in controls = 13%; P = 4.99 × 10(-4), odds ratio = 1.32) in significance. Imputation and subsequent association analysis showed evidence of association (P < 0.05) at 27 additional SNPs within intron 1. Cross-ethnic meta-analysis, assuming an additive genetic model adjusted for population proportions, showed five SNPs with significant P-values (1.40 × 10(-3) < P< 3.97 × 10(-2)), with one (rs704848) remaining significant after Bonferroni correction (P(meta) = 2.66 × 10(-2)). Our study independently confirms and extends the association of SLE with CD247, which is shared by various autoimmune disorders and supports a common T-cell-mediated mechanism.

Assessing and ensuring patient safety during breath-holding for radiotherapy

Objective:

While there is recent interest in using repeated deep inspiratory breath-holds, or prolonged single breath-holds, to improve radiotherapy delivery, breath-holding has risks. There are no published guidelines for monitoring patient safety, and there is little clinical awareness of the pronounced blood pressure rise and the potential for gradual asphyxia that occur during breath-holding. We describe the blood pressure rise during deep inspiratory breath-holding with air and test whether it can be abolished simply by pre-oxygenation and hypocapnia.

Methods:

We measured blood pressure, oxygen saturation (SpO₂) and heart rate in 12 healthy, untrained subjects performing breath-holds.

Results:

Even for deep inspiratory breath-holds with air, the blood pressure rose progressively (e.g. mean systolic pressure rose from 133 ± 5 to 175 ± 8 mmHg at breakpoint, p < 0.005, and in two subjects, it reached 200 mmHg). Pre-oxygenation and hypocapnia prolonged breath-hold duration and prevented the development of asphyxia but failed to abolish the pressure rise. The pressure rise was not a function of breath-hold duration and was not signalled by any fall in heart rate (remaining at resting levels of 72 ± 2 beats per minute).

Conclusion:

Colleagues should be aware of the progressive blood pressure rise during deep inspiratory breath-holding that so far is not easily prevented. In breast cancer patients scheduled for breath-holds, we recommend routine screening for heart, cardiovascular, renal and cerebrovascular disease, routine monitoring of patient blood pressure and SpO₂ during breath-holding and requesting patients to stop if systolic pressure rises consistently >180 mmHg and or SpO₂ falls <94%.

Advances in knowledge:

There is recent interest in using deep inspiratory breath-holds, or prolonged single breath-holding techniques, to improve radiotherapy delivery. But there appears to be no clinical awareness of the risks to patients from breath-holding. We demonstrate the progressive blood pressure rise during deep inspiratory breath-holds with air, which we show cannot be prevented by the simple expedient of pre-oxygenation and hypocapnia. We propose patient screening and safety guidelines for monitoring both blood pressure and SpO₂ during breath-holds and discuss their clinical implications.

Independent contribution of bronchoalveolar lavage and serum galactomannan in the diagnosis of invasive pulmonary aspergillosis

The optimal combination of galactomannan index (GMI) testing for the diagnosis of invasive pulmonary aspergillosis (IPA) remains unclear. For diagnostic approaches that are triggered by clinical signs and symptoms in high-risk patients, institutional variation remains, with some centers routinely relying on only serum GMI or bronchoalveolar lavage (BAL) GMI testing. In addition, use of mold-active agents before diagnosis of IPA is becoming increasingly common, and understanding the effect of these drugs on test yield is important when making time-critical treatment decisions. In a single-center cohort of 210 allogeneic hematopoietic cell transplant recipients, we found that serum and BAL GMI testing contributed independently to IPA diagnosis, supporting the practice of sending both tests simultaneously to ensure a timely diagnosis of IPA. BAL GMI sensitivity was not affected by receipt of mold-active therapy in our cohort.

Breast cancer risk following Hodgkin lymphoma radiotherapy in relation to menstrual and reproductive factors

BACKGROUND

Women treated with supradiaphragmatic radiotherapy (sRT) for Hodgkin lymphoma (HL) at young ages have a substantially increased breast cancer risk. Little is known about how menarcheal and reproductive factors modify this risk.

METHODS

We examined the effects of menarcheal age, pregnancy, and menopausal age on breast cancer risk following sRT in case-control data from questionnaires completed by 2497 women from a cohort of 5002 treated with sRT for HL at ages <36 during 1956-2003.

RESULTS

Two-hundred and sixty women had been diagnosed with breast cancer. Breast cancer risk was significantly increased in patients treated within 6 months of menarche (odds ratio (OR) 5.52, 95% confidence interval (CI) (1.97-15.46)), and increased significantly with proximity of sRT to menarche (Ptrend<0.001). It was greatest when sRT was close to a late menarche, but based on small numbers and needing reexamination elsewhere. Risk was not significantly affected by full-term pregnancies before or after treatment. Risk was significantly reduced by early menopause (OR 0.55, 95% CI (0.35-0.85)), and increased with number of premenopausal years after treatment (Ptrend=0.003).

CONCLUSION

In summary, this paper shows for the first time that sRT close to menarche substantially increases breast cancer risk. Careful consideration should be given to follow-up of these women, and to measures that might reduce their future breast cancer risk.

Active systemic lupus erythematosus is associated with failure of antigen-presenting cells to express programmed death ligand-1

OBJECTIVE

Antigen-presenting cells (APC) play critical roles in establishing and maintaining peripheral tolerance. This is accomplished in part via expression of negative co-stimulatory molecules such as programmed death ligand-1 (PD-L1) on tolerogenic APC, such as immature myeloid dendritic cells (mDC). Several studies have strongly linked dysfunction of APC, including mDC, to the pathogenesis of SLE. The objective of this study was to determine whether APC expressed PD-L1 protein at normal levels during active lupus.

METHODS

Peripheral blood mononuclear cells (PBMC) were isolated from 19 paediatric patients with SLE and from 17 healthy age-matched controls. PBMC from both cohorts were cultured in the absence of exogenously added stimuli, and leucocyte PD-L1 expression was measured by flow cytometry.

RESULTS

Immature mDC and monocytes (Mo) from healthy children expressed little PD-L1 at initial isolation, but spontaneously up-regulated PD-L1 by 24 h. In contrast, both mDC and Mo from patients with active SLE failed to up-regulate PD-L1 over a 5 day time course, expressing this protein only during disease remissions.

CONCLUSIONS

These data are the first to link active lupus with reversibly decreased PD-L1 expression on professional APC, suggesting a novel mechanism for loss of peripheral tolerance in SLE.

Studies on the control of mucin production

The process of synthesizing a mucin molecule is discussed, primarily from the standpoint of glycoconjugate biosynthesis. The control of the activation steps in the making of nucleotide sugars is detailed, stressing the molecular mechanisms operating. These include: supply of glycolytic intermediates; the pyridine nucleotide redox potential; the energy state as expressed in nucleotide potential; and feedback modifiers. Next, the glycosyl transferases are discussed, as are suggestions of control at the first committment step and the subjects of specificity of donor and acceptor molecules and the associational state of the glycosyl transferases. The secondpart of the paper describes a model system in vivo. The paired cat submandibular glands are exposed and, in one, blood supply and salivary duct are cannulated and the parasympathetic and sympathetic nerve exposed. This preparation uses the contralateral gland as control and enables certain questions to be asked: 1. Does the cell produce incomplete mucins when the biosynthetic rate is high? 2. Does the energy state of the cell 'keep up with' the high rates of synthesis? 3. What is the extent of post-synthetic modifications? 4. What cell types are involved in mucin elicited by different chemical or electrical stimuli? 5. What is the time involved in synthesis and storage?

Human leukocyte antigen class II alleles in Caucasian women with primary biliary cirrhosis

In the current study, we investigated human leukocyte antigen (HLA) class II alleles in Caucasian women with primary biliary cirrhosis (PBC), a disease that preferentially affects women. Alleles of DRB1, DQA1, and DQB1 were determined by DNA-based HLA typing for women with PBC (n = 72) and healthy women (n = 381). All study subjects were Caucasian. HLA DRB1*08 was significantly increased in women with PBC compared to healthy women. The increase was primarily due to the DRB1*0801 allele, also the most common DRB1*08 allele among controls. DQB1*04 and DQA1*0401 were significantly increased. DRB1*1501, DQA1*0102, and DQB1*0602 were associated with decreased risk. Analyses conducted comparing parous women with PBC to parous healthy women (n = 68 and n = 282, respectively) yielded similar significant results. Although the DRB1*08-DQA1*0401-DQB1*04 haplotype was significantly associated with PBC, consistent with other studies, this haplotype nevertheless represented only 19% (14/72) of all PBC patients and can account for only a minority of the risk of PBC.

Male microchimerism in women with systemic sclerosis and healthy women who have never given birth to a son

BACKGROUND

Male DNA or cells are often used to measure microchimerism in a woman. In studies of autoimmune diseases male microchimerism is most often attributed to the previous birth of a son.

OBJECTIVE

To determine the frequency of male microchimerism in healthy women or women with systemic sclerosis who had never given birth to a son.

METHODS

Real time quantitative polymerase chain reaction targeting the Y chromosome specific sequence DYS14 was employed to test DNA extracted from peripheral blood mononuclear cells of 26 women with systemic sclerosis and 23 healthy women who had never given birth to a son.

RESULTS

are expressed as the genome equivalent number of male cells per million host cells (gEq/mil).Results: Male DNA was found in 15% of women with systemic sclerosis (range 0 to 23.7 gEq/mil) and in 13% of healthy women (range 0 to 5.1 gEq/mil). Although two women with male DNA had an induced abortion, most had no history of spontaneous or induced abortion (either systemic sclerosis or healthy).

CONCLUSIONS

Microchimerism with male DNA can be found in the circulation of women who have never given birth to a son. Thus sources other than a male birth must be considered when male DNA is used to measure microchimerism. Although other studies are needed, there was no apparent difference in women with systemic sclerosis and healthy women. Possible sources of male DNA include unrecognised male pregnancy or unrecognised male twin, an older male sibling with transfer through the maternal circulation, or sexual intercourse alone.

Maternal and sibling microchimerism in twins and triplets discordant for neonatal lupus syndrome-congenital heart block

OBJECTIVE

Neonatal lupus syndrome-congenital heart block (NLS-CHB) is an acquired autoimmune disease in which maternal autoantibodies are necessary but not sufficient for disease. Maternal myocardial cells have been found in the hearts of patients with NLS-CHB, suggesting that maternal microchimerism may also play a role. In this study we asked whether levels of microchimerism in the blood are associated with NLS-CHB in discordant twins and triplets.

METHODS

Human leucocyte antigen (HLA)-specific and Y-chromosome-specific real-time quantitative polymerase chain reaction (PCR) was used to quantitatively assay maternal and sibling microchimerism in peripheral blood. Because of HLA allele sharing in families, it was not always possible to distinguish between multiple sources of microchimerism.

RESULTS

In one family, maternal and/or sibling microchimerism was detected in two triplets who had CHB, but not in the triplet with transient hepatitis. Levels ranged from 4 to 948 genome-equivalents of foreign deoxyribonucleic acid per million host genome-equivalents (gEq/million). Over the first year levels of sibling microchimerism decreased in the triplet with complete CHB and increased in the triplet who progressed from first- to second-degree CHB. In a second family, maternal and/or sibling microchimerism was detected in the healthy twin (1223 gEq/million) but not in the twin with CHB.

CONCLUSIONS

Maternal and/or sibling microchimerism was detectable in the blood of infant twins and triplets discordant for NLS. Microchimerism in the blood was not specific for NLS-CHB, although in one family levels correlated with disease. Thus, microchimerism in the blood and/or tissues may be involved in the pathogenesis or progression of NLS-CHB, but additional factors must also contribute. Further investigation is warranted.

Microbiological examination of ready-to-eat stuffing from retail premises in the north-east of England. The 'Get Stuffed' survey

AIMS

To establish the microbiological quality of ready-to-eat stuffing from retail premises in the north-east of England. To establish threshold levels of bacteria in the product for acceptance as a ready-to-eat food. To determine the relationship between the microbiology of the product and production processes.

METHODS AND RESULTS

A microbiological study of ready-to-eat stuffing using validated methods was performed on 147 samples from 139 retail premises. The determinants investigated were as follows: aerobic colony count, Escherichia coli, Enterobacteriaceae, Staphylococcus aureus, Bacillus spp., Salmonella spp. and Campylobacter spp. Results indicate that using current guidelines 76.3% were satisfactory, 15.6% were acceptable and 8.2% were of unsatisfactory quality.

CONCLUSIONS

Unsatisfactory results were due to high aerobic colony counts, E. coli, Enterobacteriaceae and S. aureus. There were significant associations between bacteriological quality and temperature of storage, food hygiene training, product discard policy and confidence in management scores.

SIGNIFICANCE AND IMPACT OF THE STUDY

The microbiology of ready-to-eat stuffing suggests that this is a relatively safe product. It is suggested that the product be placed in food category 3 in the current guidelines for ready-to-eat foods.

Cat scratch disease (CSD) in patients with stellate neuroretinitis: 3 cases

This case series describes three patients with a similar clinical picture: unilateral abrupt visual loss, optic nerve edema, and a macular star exudate. In all cases we found significant antibody titers to Bartonella henselae, the causative agent of cat scratch disease. Cat scratch disease seems to be the most common cause of stellate neuroretinitis, formerly known as Leber's idiopathic stellate retinopathy. A review of the pertinent literature shows that serologic evidence of B. henselae is sufficient to confirm the diagnosis given the low incidence of significant titers in the general population. Cat scratch disease is usually a self limiting disorder in immunocompetent patients, but treatment with doxycycline is recommended.

Polymyositis as a manifestation of chronic graft-versus-host disease

OBJECTIVE

Chronic graft-versus-host disease (GVHD) after haematopoietic stem cell transplantation (HSCT) has similarities to some idiopathic autoimmune diseases, including polymyositis. To investigate the relationship between chronic GVHD and idiopathic myositis we conducted a detailed analysis of all cases of myositis occurring in a large series of HSCT patients.

METHODS

We conducted a retrospective chart review of all cases of myositis that developed in 7161 patients who underwent HSCT at the Fred Hutchinson Cancer Research Center between 1969 and 1999.

RESULTS

Among 1859 individuals who developed chronic GVHD, 12 developed myositis. No patients developed myositis without chronic GVHD. Myositis was first identified between 7 and 55 months after transplantation. In histopathology, electromyography, laboratory values and response to immunosuppressive therapy, the cases resembled idiopathic polymyositis. Autoantibodies were found in eight cases.

CONCLUSIONS

Myositis in the chronic GVHD population occurred with an incidence higher than expected by chance, suggesting that muscle may be a target tissue for chronic GVHD. Recent studies have implicated allogeneic cells persisting after maternal-fetal cell transfer in selected autoimmune diseases, including myositis. This report lends support to the possibility that both idiopathic myositis and chronic GVHD-related myositis could involve allo-autoimmune responses.

From the simple detection of microchimerism in patients with autoimmune diseases to its implication in pathogenesis

Long-term persistence of fetal cells in parous women (fetal microchimerism, FM) as well as maternal cells in their offspring (maternal microchimerism, MM) have been reported. Systemic sclerosis (SSc), primary biliary cirrhosis (PBC), and Sjögren's syndrome (SS) share similar epidemiology with a predilection for females following childbearing years, with clinical similarities to chronic graft-versus-host disease, a known condition of chimerism. This led to the hypothesis that FM could be involved in the pathogenesis of autoimmune diseases. Initial investigations were conducted in SSc, where the hypothesis was supported by the more frequent occurrence and, quantitatively, a greater degree of FM in women with SSc compared to matched healthy women. Long-term persistence, however, of fetal cells in healthy women indicates that FM per se is not sufficient for causing SSc, but may be important in the context of other risk factors, such as genetic susceptibility and HLA relationship among host and nonhost cells. Contradictory results have recently been published for both PBC and SS and cause difficulty in drawing any conclusions about the role of FM in their pathogenesis. On the other hand, MM has been investigated as a risk factor in patients with systemic lupus (SLE) and juvenile dermatomyositis (JDM). A potential role of MM has been suggested in the pathogenesis of SLE. Recent publications also support the hypothesis that MM might lead to increased risks for JDM. In conclusion, contradictory results have been observed. This reflects a need for standardization of protocols and the selection of control populations. Detection of microchimerism has to be quantitatively studied in the context of genetic factors in order to study its relationship to the pathogenesis of autoimmune diseases.

Amino acid residues in LuxR critical for its mechanism of transcriptional activation during quorum sensing in Vibrio fischeri

PCR-based site-directed mutagenesis has been used to generate 38 alanine-substitution mutations in the C-terminal 41 amino acid residues of LuxR. This region plays a critical role in the mechanism of LuxR-dependent transcriptional activation of the Vibrio fischeri lux operon during quorum sensing. The ability of the variant forms of LuxR to activate transcription of the lux operon was examined by using in vivo assays in recombinant Escherichia coli. Eight recombinant strains produced luciferase at levels less than 50% of that of a strain expressing wild-type LuxR. Western immunoblotting analysis verified that the altered forms of LuxR were expressed at levels equivalent to those of the wild type. An in vivo DNA binding-repression assay in recombinant E. coli was subsequently used to measure the ability of the variant forms of LuxR to bind to the lux box, the binding site of LuxR at the lux operon promoter. All eight LuxR variants found to affect cellular luciferase levels were unable to bind to the lux box. An additional 11 constructs that had no effect on cellular luciferase levels were also found to exhibit a defect in DNA binding. None of the alanine substitutions in LuxR affected activation of transcription of the lux operon without also affecting DNA binding. These results support the conclusion that the C-terminal 41 amino acids of LuxR are important for DNA recognition and binding of the lux box rather than positive control of the process of transcription initiation.

Synthesis and activity of selective MMP inhibitors with an aryl backbone

A series of novel, MMP-1 sparing arylhydroxamate sulfonamides with activity against MMP-2 and -13 is described.

Structural insights into the stereochemistry of the cyclooxygenase reaction

Cyclooxygenases are bifunctional enzymes that catalyse the first committed step in the synthesis of prostaglandins, thromboxanes and other eicosanoids. The two known cyclooxygenases isoforms share a high degree of amino-acid sequence similarity, structural topology and an identical catalytic mechanism. Cyclooxygenase enzymes catalyse two sequential reactions in spatially distinct, but mechanistically coupled active sites. The initial cyclooxygenase reaction converts arachidonic acid (which is achiral) to prostaglandin G2 (which has five chiral centres). The subsequent peroxidase reaction reduces prostaglandin G2 to prostaglandin H2. Here we report the co-crystal structures of murine apo-cyclooxygenase-2 in complex with arachidonic acid and prostaglandin. These structures suggest the molecular basis for the stereospecificity of prostaglandin G2 synthesis.

Involvement of the RNA polymerase alpha-subunit C-terminal domain in LuxR-dependent activation of the Vibrio fischeri luminescence genes

LuxR is a sigma(70) RNA polymerase (RNAP)-dependent transcriptional activator that controls expression of the Vibrio fischeri lux operon in response to an acylhomoserine lactone-cell density signal. We have investigated whether the alpha-subunit C-terminal domain (alphaCTD) of RNAP is required for LuxR activity. A purified signal-independent, LuxR C-terminal domain-containing polypeptide (LuxRDeltaN) was used to study the activation of transcription from the luxI promoter in vitro. Initiation of lux operon transcription was observed in the presence of LuxRDeltaN and wild-type RNAP but not in the presence of LuxRDeltaN and RNAPs with truncated alphaCTDs. We also studied the in vivo role of the RNAP alphaCTD in activation of lux transcription in Escherichia coli. This enabled a comparison of results obtained with full-length LuxR to those obtained with LuxRDeltaN. These in vivo studies indicated that both LuxR and LuxRDeltaN require the RNAP alphaCTD for activity. The results of DNase I protection studies showed that LuxRDeltaN-RNAP complexes can bind and protect the luxI promoter, but with less efficacy when the alphaCTD is truncated in comparison to the wild type. Thus, both in vitro and in vivo experiments demonstrated that LuxR-dependent transcriptional activation of the lux operon involves the RNAP alphaCTD and suggest that alphaCTD-LuxR interactions may play a role in recruitment of RNAP to the luxI promoter.

Synthesis and identification of conformationally constrained selective MMP inhibitors

We have discovered a new series of potent conformationally constrained MMP Inhibitors that are selective for MMP-13 over MMP-1.

Mutational analysis of the Vibrio fischeri LuxI polypeptide: critical regions of an autoinducer synthase

Synthesis of the Vibrio fischeri autoinducer, a signal involved in the cell density-dependent activation of bioluminescence, is directed by the luxI gene product. The LuxI protein catalyzes the synthesis of N-acyl-homoserine lactones from S-adenosylmethionine and acylated-acyl carrier protein. We have gained an appreciation of the LuxI regions and amino acid residues involved in autoinducer synthesis by isolating and analyzing mutations generated by random and site-specific mutagenesis of luxI. By random mutagenesis we isolated 13 different single amino acid substitutions in the LuxI polypeptide. Eleven of these substitutions resulted in no detectable autoinducer synthase activity, while the remaining two amino acid substitutions resulted in reduced but detectable activity. The substitutions that resulted in no detectable autoinducer synthase activity mapped to two small regions of LuxI. In Escherichia coli, wild-type luxI showed dominance over all of the mutations. Because autoinducer synthesis has been proposed to involve formation of a covalent bond between an acyl group and an active-site cysteine, we constructed site-directed mutations that altered each of the three cysteine residues in LuxI. All of the cysteine mutants retained substantial activity as an autoinducer synthase in E. coli. Based on the analysis of random mutations we propose a model in which there are two critical regions of LuxI, at least one of which is an intimate part of an active site, and based on the analysis of site-directed mutations we conclude that an active-site cysteine is not essential for autoinducer synthase activity.

Cross-species induction of luminescence in the quorum-sensing bacterium Vibrio harveyi

Different species of bacteria were tested for production of extracellular autoinducer-like activities that could stimulate the expression of the luminescence genes in Vibrio harveyi. Several species of bacteria, including the pathogens Vibrio cholerae and Vibrio parahaemolyticus, were found to produce such activities. Possible physiological roles for the two V. harveyi detection-response systems and their joint regulation are discussed.

Quorum sensing in Vibrio fischeri: essential elements for activation of the luminescence genes

LuxR is required for cell density-dependent activation of the Vibrio fischeri luminescence (lux) genes. It has not been possible to study full-length LuxR in vitro, but a polypeptide containing the C-terminal transcriptional-activator domain of LuxR (LuxRdeltaN) has been purified, and its binding to lux regulatory DNA has been investigated. By itself, LuxRdeltaN interacts with a region of lux regulatory DNA that is upstream of the lux box, which is a 20-bp element that is required for LuxR activation of the luminescence operon. Individually, neither the purified LuxRdeltaN nor RNA polymerase binds to the lux box region, but together the two proteins bind in synergy to the lux box-luxI promoter region. We show that binding of LuxRdeltaN to the upstream region is not a prerequisite for its synergistic binding with RNA polymerase to the lux box and the luxI promoter region. We also show that LuxRdeltaN and RNA polymerase are both required and sufficient for transcriptional activation of the lux operon. This argues against the hypothesis that LuxR functions to alleviate repression of the lux operon by another cellular factor. Rather, our data support the view that LuxR functions as an accessory factor that enables RNA polymerase to bind to and initiate transcription from the promoter of the lux operon.

Adenocarcinoma of the cervix: a regional retrospective study

A retrospective study using data from the Yorkshire Cancer Registry was undertaken to investigate the incidence, characteristics and prognosis of cases of cervical adenocarcinoma in the Yorkshire Region. Three hundred and twenty-six women resident in the Yorkshire Region formed the basis of the study. The overall five year survival for adenocarcinoma of the cervix is 53%. This was influenced by stage, lymph node involvement and differentiation. 37 out of 122 surgically treated patients received inappropriate treatment. There is a need for improved data collection in the treatment of these patients. This lends weight to the argument that cancer of the cervix should be managed in cancer units.

Structural basis for selective inhibition of cyclooxygenase-2 by anti-inflammatory agents

Prostaglandins and glucocorticoids are potent mediators of inflammation. Non-steroidal anti-inflammatory drugs (NSAIDs) exert their effects by inhibition of prostaglandin production. The pharmacological target of NSAIDs is cyclooxygenase (COX, also known as PGH synthase), which catalyses the first committed step in arachidonic-acid metabolism. Two isoforms of the membrane protein COX are known: COX-1, which is constitutively expressed in most tissues, is responsible for the physiological production of prostaglandins; and COX-2, which is induced by cytokines, mitogens and endotoxins in inflammatory cells, is responsible for the elevated production of prostaglandins during inflammation. The structure of ovine COX-1 complexed with several NSAIDs has been determined. Here we report the structures of unliganded murine COX-2 and complexes with flurbiprofen, indomethacin and SC-558, a selective COX-2 inhibitor, determined at 3.0 to 2.5 A resolution. These structures explain the structural basis for the selective inhibition of COX-2, and demonstrate some of the conformational changes associated with time-dependent inhibition.

[Illegal drug use by secondary school children in Belgium: north-south differences]

The study "Health Behaviour of Youngsters" regularly provides comparative data on health behaviour and related lifestyle of pupils from 11 to 18 years old. This study is based on repeated surveys among randomised representative samples of pupils, following the international standardised protocol from the WHO cross-national survey "Health Behaviour in School-aged Children". In Belgium, results from the 1990 survey (sample = 3528) show differences in illegal drugs use between the South (French-speaking) and the North (Flemish-speaking). For example, among the 17 year olds, 9.8% of the French-speaking pupils and 5.5% of the Flemish-speaking have already tried illegal drug(s) and in the same age groups, 2.9% and 1.5%, respectively declare to be regular users. The first hypotheses concerning those differences take into account the socio-economic and cultural environment as well as methodological problems inherent to these surveys.

Three-dimensional structure of human cytomegalovirus protease

Herpesviruses encode a serine protease that specifically cleaves assembly protein. This protease is critical for replication, and represents a new target for antiviral drug design. Here we report the three-dimensional structure of the protease from human cytomegalovirus (hCMV) at 2.27 angstroms resolution. The structure reveals a unique fold and new catalytic strategy for cleavage. The monomer fold of the enzyme, a seven-stranded beta-barrel encircled by a chain of helices that form the carboxy terminus of the molecule, is unrelated to those observed in classic serine proteases such as chymotrypsin and subtilisin. The serine nucleophile at position 132 is activated by two juxtaposed histidine residues at positions 63 and 157. Dimerization, which seems to be necessary for activity, is observed in the crystals. Correlations of the structure with the sequences of herpesvirus proteases suggest that dimerization may confer specificity and recognition in substrate binding.

Hepatosplenic abscesses due to Brucella melitensis: report of a case involving a child and review of the literature

Suppurative disease of the liver and/or spleen is a rare and serious complication of human brucellosis. In the English-language literature, only nine cases have been reported, all involving adults with chronic infection. We report the case of a young child in whom abscesses of the liver and spleen developed during acute brucellosis. Brucella melitensis was cultured from an aspirate of the liver and from the bone marrow. After percutaneous drainage of the liver abscess, the patient responded to a 56-day course of antimicrobial therapy. To our knowledge, this is the first reported case of hepatosplenic abscess due to a Brucella species in a child.

Conjugative transposons: an unusual and diverse set of integrated gene transfer elements

Conjugative transposons are integrated DNA elements that excise themselves to form a covalently closed circular intermediate. This circular intermediate can either reintegrate in the same cell (intracellular transposition) or transfer by conjugation to a recipient and integrate into the recipient's genome (intercellular transposition). Conjugative transposons were first found in gram-positive cocci but are now known to be present in a variety of gram-positive and gram-negative bacteria also. Conjugative transposons have a surprisingly broad host range, and they probably contribute as much as plasmids to the spread of antibiotic resistance genes in some genera of disease-causing bacteria. Resistance genes need not be carried on the conjugative transposon to be transferred. Many conjugative transposons can mobilize coresident plasmids, and the Bacteroides conjugative transposons can even excise and mobilize unlinked integrated elements. The Bacteroides conjugative transposons are also unusual in that their transfer activities are regulated by tetracycline via a complex regulatory network.

Using sampling techniques in protein crystallization

The crystallization of homogeneous or highly purified macromolecules depends on many variables such as precipitant, pH, choice of buffer, protein concentration, temperature, the participation of different mono- and divalent ions, as well as the presence of minute amounts of detergent and organic molecules. Finding the best combination among these many parameters is a multi-variable optimization problem. This kind of problem can be treated mathematically by sampling techniques. We have used this technique for protein crystallization. The iterative procedure starts with random sampling, followed by quantitative evaluation and cycles with weighted sampling. A simple procedure, derived from this concept and called MON48, has been successfully applied to many protein crystallization problems.

Biphasic transcriptional regulation of the interferon regulatory factor-1 gene by prolactin: involvement of gamma-interferon-activated sequence and Stat-related proteins

Stimulation of quiescent Nb2 T cells by PRL leads to the rapid transcriptional activation of a T cell activation gene, interferon regulatory factor-1 (IRF-1). IRF-1 is induced twice by PRL in a single cell cycle, first during G1 at 30-60 min and again over early S phase at 10-12 h. By nuclear run-on transcription analysis of IRF-1 promoter-chloramphenicol acetyl transferase (CAT) constructs, the -1.7 kilobase (kb) 5'-flanking IRF-1 DNA was shown to contain elements that mediate both G1 and S phase expression. The -200 bp IRF-1 promoter DNA contains elements that respond to G1 PRL stimulation in a protein synthesis independent manner, suggesting the involvement of pre-existing factors. Further promoter deletion analysis delineated a minimal PRL responsive region between -112 and -205 bp. Within this region is a Gamma Interferon Activated Sequence or GAS, consisting of two inverted GAAA motifs (-123/-113), which confers PRL-inducible expression to a reporter gene, suggesting that GAS can function as a PRL responsive element. Further, GAS exhibits binding with nuclear proteins in a PRL-inducible, cell cycle-dependent manner. One of these proteins appears to be related to the emerging family of Signal Transducer and Activator of Transcription or Stat factors. These studies suggest that the GAS site and Stat-like proteins participate in PRL receptor signal transduction to regulate the biphasic expression of the IRF-1 gene in PRL-stimulated T cells.

Synergistic binding of the Vibrio fischeri LuxR transcriptional activator domain and RNA polymerase to the lux promoter region

LuxR, the Vibrio fischeri luminescence gene (lux) activator, is the best-studied member of a family of bacterial transcription factors required for cell density-dependent expression of specific genes involved in associations with eukaryotic hosts. Neither LuxR nor any other LuxR homolog has been shown to bind DNA directly. We have purified the LuxR C-terminal transcriptional activator domain from extracts of recombinant Escherichia coli in which this polypeptide was expressed. The purified polypeptide by itself binds to lux regulatory DNA upstream of the lux box, a 20-bp palindrome that is required for LuxR activity in vivo, but it does not bind to the lux box. However, the LuxR C-terminal domain together with RNA polymerase protects a region including the lux box and the lux operon promoter from DNase I cleavage. There is very little protection of the lux operon promoter region from DNase I digestion in the presence of RNA polymerase alone. Apparently, there is a synergistic binding of the LuxR C-terminal domain and RNA polymerase to the promoter region. The upstream binding region for the purified polypeptide encompasses a binding site for cAMP receptor protein (CRP). Under some conditions, CRP binding can block the binding of the LuxR C-terminal domain to the upstream binding region, and it can also block the synergistic binding of the LuxR C-terminal domain and RNA polymerase to the lux box and luminescence gene promoter region. This description of DNA binding by the LuxR C-terminal domain should lead to an understanding of the molecular interactions of the LuxR family of transcriptional activators with regulatory DNA.

Renin inhibitor SC-51106 complexed with human renin: discovery of a new binding site adjacent to P3

SC-51106, a 'minimal-size' diol-based renin inhibitor lacking a P4 residue, has been co-crystallized with human renin and the structure of the complex determined by X-ray crystallography. This study defines the mode of binding of this important class of renin inhibitor, and in conjunction with molecular modeling, has led to the discovery of a new binding site adjacent to S3, which is termed the 'S3aux(iliary)' subsite.

Multiple prolactin-responsive elements mediate G1 and S phase expression of the interferon regulatory factor-1 gene

The interferon regulatory factor-1 (IRF-1) gene is both an immediate-early G1 phase gene and an S phase gene inducible by PRL in rat Nb2 T lymphocytes. To understand the mechanism by which PRL regulates the biphasic expression of IRF-1, we cloned the rat IRF-1 gene and functionally characterized the IRF-1 promoter. Upon transfection into Nb2 T cells, 1.7 kilobases (kb) of IRF-1 5'-flanking DNA linked to a chloramphenicol acetyl transferase (CAT) reporter gene mediated a 30-fold induction of CAT enzyme activity in response to 24 h of PRL stimulation. Deletion mutants containing 1.3, 0.6, and 0.2 kb 5'-flanking DNA were incrementally less transcriptionally active, although 0.2 kb still mediated a 12-fold induction by PRL. The sequence between -1.7 and -0.2 kb linked to a heterologous thymidine kinase promoter failed to respond to PRL stimulation, suggesting that the activity of upstream PRL response elements may require an interaction with promoter-proximal elements. By assaying CAT enzyme activity across a 24-h PRL induction time course, we were able to assign G1 vs. S phase PRL responses of the IRF-1 gene to different regions of the IRF-1 5'-flanking and promoter DNA. The 0.2-kb IRF-CAT construct was induced by PRL stimulation during the G1 phase of the cell cycle. In contrast, the 1.7-kb IRF-CAT construct was inducible by PRL during both G1 and S phase of the cell cycle. Hence, the PRL-induced biphasic expression of the IRF-1 gene appears to be controlled by separate PRL-responsive elements: elements in the first 0.2 kb of the IRF-1 promoter region act during early activation, and elements between 0.2 and 1.7 kb act in concert with the proximal 0.2-kb region during S phase progression.

Ophthalmic manifestations of infections with Cryptococcus neoformans in patients with the acquired immunodeficiency syndrome

The present study was undertaken to determine the nature and the prevalence of ophthalmic manifestations of infections with Cryptococcus neoformans in human immunodeficiency virus seropositive patients and to analyze whether the presence or absence of ocular signs is associated with improved survival. Eighty human immunodeficiency virus seropositive patients with cryptococcal infection were enrolled. We observed papilledema in 26 of the 80 patients (32.5%). Visual loss and abducens nerve palsy occurred in seven patients (9%). Only two patients (2.5%) had optic atrophy. Visual loss caused by optic nerve involvement was less frequent among the 62 patients treated with oral conazoles exclusively than among the 18 patients who had received amphotericin B or a combination of amphotericin B and conazoles. Actual invasion of the intraocular structures with Cryptococcus neoformans was an uncommon complication in our series. In addition to the ocular manifestations attributable to cryptococcal disease, human immunodeficiency virus-related retinopathy was present in nearly half of the patients. Cytomegalovirus retinitis was diagnosed in four patients (5%). The 26 patients (32.5%) with papilledema had a median survival of 182 days vs 160 days for the patients without papilledema. The median survival for 18 patients (22.5%) with cotton-wool spots was 102 days vs 186 days for those without cotton-wool spots. The differences between these subgroups were not statistically significant.

Excision, transfer, and integration of NBU1, a mobilizable site-selective insertion element

The Bacteroides species harbor a family of conjugative transposons called tetracycline resistance elements (Tcr elements) that transfer themselves from the chromosome of a donor to the chromosome of a recipient, mobilize coresident plasmids, and also mediate the excision and circularization of members of a family of 10- to 12-kbp insertion elements which share a small region of DNA homology and are called NBUs (for nonreplicating Bacteroides units). The NBUs are sometimes cotransferred with Tcr elements, and it was postulated previously that the excised circular forms of the NBUs were plasmidlike forms and were transferred like plasmids and then integrated into the recipient chromosome. We used chimeric plasmids containing one of the NBUs, NBU1, and a Bacteroides-Escherichia coli shuttle vector to show that this hypothesis is probably correct. NBU1 contained a region that allowed mobilization by both the Tcr elements and IncP plasmids, and we used these conjugal elements to allow us to estimate the frequencies of excision, mobilization, and integration of NBU1 in Bacteroides hosts to be approximately 10(-2), 10(-5) to 10(-4), and 10(-2), respectively. Although functions on the Tcr elements were required for the excision-circularization and mobilization of NBU1, no Tcr element functions were required for integration into the recipient chromosome. Analysis of the DNA sequences at the integration region of the circular form of NBU1, the primary insertion site in the Bacteroides thetaiotaomicron 5482 chromosome, and the resultant NBU1-chromosome junctions showed that NBU1 appeared to integrate into the primary insertion site by recombining within an identical 14-bp sequence present on both NBU1 and the target, thus leaving a copy of the 14-bp sequence at both junctions. The apparent integration mechanism and the target selection of NBU1 were different from those of both XBU4422, the only member of the conjugal Tcr elements for which these sequences are known, and Tn4399, a mobilizable Bacteroides transposon. The NBUs appear to be a distinct type of mobilizable insertion element.

Tetracycline regulation of genes on Bacteroides conjugative transposons

Human colonic Bacteroides species harbor a family of large conjugative transposons, called tetracycline resistance (Tcr) elements. Activities of these elements are enhanced by pregrowth of bacteria in medium containing tetracycline, indicating that at least some Tcr element genes are regulated by tetracycline. Previously, we identified a central regulatory locus on the Tcr elements that contained two genes, rteA and rteB, which appeared to encode a two-component regulatory system (A. M. Stevens, J. M. Sanders, N. B. Shoemaker, and A. A. Salyers, J. Bacteriol. 174:2935-2942, 1992). In the present study, we describe a gene which is located downstream of rteB in a separate transcriptional unit and which requires RteB for expression. Sequence analysis of this gene showed that it encoded a 217-amino-acid protein, which had no significant sequence similarity to any proteins in the GenBank or EMBL data base. An insertional disruption in the gene abolished self-transfer of the Tcr element to Bacteroides recipients, indicating that the gene was essential for self-transfer. The disruption also affected mobilization of coresident plasmids. Mobilization frequency was reduced 100- to 1,000-fold if the recipient was Escherichia coli but was not affected to the same extent if the recipient was an isogenic Bacteroides strain. The complex phenotype of the disruption mutant suggested that the newly identified gene, like rteA and rteB, had a regulatory function. Accordingly, it has been designated rteC. Our results indicate that regulation of Tc(r) element functions is unexpectedly complex and may involve a cascade of regulators, with RteA and RteB exerting central control over secondary regulators like RteC, which in turn control subsets of Tcr element structural genes.

Mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1) and its determinants: a cohort study in Kigali, Rwanda

The authors report the results of the first 2 years of follow-up of a prospective cohort study on the mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1) and its determinants which started in November 1988 in Kigali, Rwanda. The study sample consists of 218 newborns of 215 HIV-1 seropositive women matched to 218 newborns of 216 HIV-1 seronegative women of the same age and parity. They were followed every 2 weeks during the first 2 years of follow-up. HIV-1 antibodies were detected by enzyme-linked immunoadsorbent assay and Western blot at 3-month intervals. Two methods of calculating the mother-to-child transmission rate were used: method 1 combines the information provided by the persistence of HIV-1 antibodies at 15 months of age in children born to HIV seropositive mothers and the excess mortality in this group compared with the cohort of children born to HIV seronegative mothers; method 2 is a case-by-case evaluation of all the children born to HIV seropositive mothers. A logistic regression model was used to study the determinants of transmission. The probability of survival at 24 months of age was 81% (95% confidence interval (CI) 75-86) in children born to seropositive mothers, compared with 95% (95% CI 92-98) in children born to seronegative mothers (p < 0.001). The mother-to-child transmission rate calculated with method 1 was 25.7% (95% CI 18.8-32.5). With method 2, the medium estimate was 24.7%. In the multivariate analysis, a CD4/CD8 ratio < 0.5 was the only maternal factor statistically associated with an increased risk of mother-to-child transmission of HIV-1 (odds ratio = 2.9, 95% CI 1.2-7.2). The authors' findings present evidence for a higher mother-to-child transmission rate of HIV-1 in children born in Rwanda than in industrialized countries.

The transcription factor interferon regulatory factor-1 is expressed during both early G1 and the G1/S transition in the prolactin-induced lymphocyte cell cycle

PRL induces quiescent Nb2 rat T-lymphoma cells to undergo mitogenesis. Upon PRL stimulation, the transcription factor interferon regulatory factor-1 (IRF-1) is induced as a novel T-cell activation gene in Nb2 cells. Surprisingly, IRF-1 is expressed twice during a single PRL-induced growth cycle: first during the early G1 phase, in an immediate transient peak from 15 min to 2 h, and second during the G1/S phase transition, in a broader peak beginning at 8 h. The unusual biphasic expression of IRF-1 mRNA is accompanied both times by de novo IRF-1 protein synthesis. However, the rate of IRF-1 protein turnover appears to be different in G1 and S phases. IRF-1 protein expressed in G1 exhibits a half-life of about 25 min, whereas in the S phase, the half-life is about 60 min. By washing out PRL at various times during G1, we found a direct correlation among the length of PRL exposure, the second peak of IRF-1 mRNA expression, and DNA synthesis. Our data suggest that PRL and one putative nuclear mediator, IRF-1, may be important in two distinct phases of the cell cycle: first in cell cycle activation, and then in S phase progression.

Interferon regulatory factor-1 is inducible by prolactin, interleukin-2 and concanavalin A in T cells

Interferon regulatory factor-1 (IRF-1) gene expression is rapidly upregulated in the prolactin (PRL)-activated Nb2 rat T lymphoma cell line. To further elucidate its role as a T cell activation molecule, IRF-1 gene expression in response to various T cell stimuli was examined. In Nb2 T cells, PRL induced two peaks of IRF-1 gene expression: a rapid, transient peak at 1 h and a sustained peak at 12 h. PRL subsequently induced interferon-gamma (IFN-gamma) gene expression at 3-6 h. However, the early induction of IRF-1 and IFN-gamma does not appear to be interdependent. Interleukin-2 (IL-2) also induced IRF-1 gene expression in Nb2 T cells but only one broad peak at 10 h was observed. In primary mouse splenocytes, concanavalin A induced rapid and transient expression of the IRF-1 gene; maximal expression occurred by 6 h, and then returned to basal levels by 12-15 h. These results provide additional evidence for the importance of IRF-1 in T cell activation.

Genes involved in production of plasmidlike forms by a Bacteroides conjugal chromosomal element share amino acid homology with two-component regulatory systems

Many human colonic Bacteroides strains carry large (greater than 70-kbp) self-transmissible chromosomal tetracycline resistance (Tcr) elements. These Tcr elements can also mediate the excision and circularization of discrete nonadjacent segments of chromosomal DNA which are designated NBUs (nonreplicating Bacteroides units). We have localized a 6.5-kbp segment of Tcr element DNA that mediates NBU excision and circularization. Analysis of the DNA sequence of this region indicated that it contained three open reading frames, all transcribed in the same direction. The first gene was the Tcr gene, tetQ. The second two open reading frames exhibited amino acid similarity to known two-component regulatory systems. Complementation and gene fusion data supported the hypothesis that the three genes were organized in an operon. Transcription from the tetQ promoter region was inducible by tetracycline, as might be expected from the previous finding that NBU excision was detectable only in cells preexposed to tetracycline. The 6.5-kbp region appeared to be essential not only for NBU excision but also for self-transfer of the elements, another activity that is enhanced by preexposure to tetracycline. Accordingly, the two genes downstream of tetQ have been designated rteA and rteB (regulation of Tcr elements).

Safety and immunogenicity of high-dose Edmonston-Zagreb measles vaccine in children with HIV-1 infection. A cohort study in Kigali, Rwanda

OBJECTIVE

To compare the reactogenicity and immunogenicity of high-dose Edmonston-Zagreb (EZ) measles vaccine in children with and without human immunodeficiency virus, type 1 (HIV-1), infection.

DESIGN

Prospective cohort study.

SETTING

General pediatric clinic and home visits in Kigali, the capital of Rwanda.

PARTICIPANTS

Infants born to HIV-1-seropositive and -seronegative mothers were vaccinated with a 10(5.0) 50% tissue culture infective dose of EZ measles vaccine at 6 months of age. Control visits were made 10 and 14 days later to monitor local and general reactions. Measles serum antibodies were measured by an enzyme-linked immunosorbent assay technique at birth and at 6 and 9 months of age. Three groups were compared: infected children (n = 43), uninfected children born to seropositive mothers (n = 135), and uninfected children born to seronegative mothers (n = 194).

RESULTS

Three hundred twenty-three children (86.8%) were available for the reactogenicity study. No statistically significant difference between the three groups was found in the occurrence of minor adverse reactions. No severe adverse reaction was observed. One hundred ninety children (51.1%) were available for the immunogenicity study. The percentage of infants negative for measles antibody at 6 months was significantly higher (P = .021) in HIV-infected children (85%) and in uninfected children born to seropositive mothers (90%) than in uninfected children born to seronegative mothers (75%). The overall seroconversion rate at 9 months was 90% (95% confidence interval, 85.7% to 94.3%), without any statistically significant difference between the three groups.

CONCLUSION

High-dose EZ vaccine administered at 6 months of age is safe and highly immunogenic in both HIV-infected and uninfected children.

Postnatal transmission of human immunodeficiency virus type 1 from mother to infant. A prospective cohort study in Kigali, Rwanda

BACKGROUND

Although transmission of human immunodeficiency virus type 1 (HIV-1) from mother to infant has been well documented during pregnancy and delivery, little is known about the possible transmission of HIV-1 during the postnatal period.

METHODS

We conducted a prospective cohort study in Kigali, Rwanda, of 212 mother-infant pairs who were seronegative for HIV-1 at delivery. All the infants were breast-fed. The subjects were followed at three-month intervals, with Western blot assays for antibodies to HIV-1 and testing of mononuclear cells by a double polymerase chain reaction (PCR) using three sets of primers. To evaluate potential risk factors, each mother who seroconverted was matched with three seronegative control women.

RESULTS

After a mean follow-up of 16.6 months, 16 of the 212 mothers became seropositive for HIV-1. Of their 16 infants, 9 became seropositive. One infant was excluded from the analysis because of a positive test by PCR on the blood sample obtained at birth. Postnatal seroconversion to HIV-1 occurred in four of the five infants born to the mothers who seroconverted during the first 3 months post partum, and in four infants of the 10 mothers who seroconverted between month 4 and month 21. In all cases, the infant seroconverted during the same three-month period as the mother. The main risk factor for maternal seroconversion was being single.

CONCLUSIONS

HIV-1 infection can be transmitted from mothers to infants during the postnatal period. Colostrum and breast milk may be efficient routes for the transmission of HIV-1 from recently infected mothers to their infants.

Perinatal transmission of HIV-1: lack of impact of maternal HIV infection on characteristics of livebirths and on neonatal mortality in Kigali, Rwanda

We present the baseline results of a prospective cohort study on the perinatal transmission of HIV-1 in Kigali, Rwanda. HIV-1-antibody testing was offered to all women of urban origin delivering a live newborn at the maternity ward of the Centre Hospitalier de Kigali from November 1988 to June 1989; 218 newborns of 215 HIV-positive mothers were matched to 218 newborns of 216 HIV-negative mothers. The matching criteria were maternal age and parity. No differences in socioeconomic characteristics were observed between HIV-positive and HIV-negative women. HIV-positive mothers more frequently reported a history of at least one death of a previously born child (P less than 0.01) and a history of abortion (P less than 0.001). Most of the HIV-positive women were asymptomatic, but 72.4% of them had a CD4; CD8 ratio less than 1 versus 10.1% in the HIV-negative group (P less than 0.001). The frequency of signs and symptoms was not statistically different in the two groups, except for a history of herpes zoster or chronic cough, which was more frequent among HIV-positive women. The rates of prematurity, low birth weight, congenital malformations and neonatal mortality were comparable in the two groups. However, infants of HIV-positive mothers had a mean birth weight 130 g lower than the infants of HIV-negative mothers (P less than 0.01). The impact of maternal HIV-1 infection on the infant seems limited during the neonatal period.

The region of a Bacteroides conjugal chromosomal tetracycline resistance element which is responsible for production of plasmidlike forms from unlinked chromosomal DNA might also be involved in transfer of the element

Large (greater than 50 kilobases) conjugal chromosomal tetracycline resistance (Tcr) elements have been found in many human colonic Bacteroides strains. Recently, N. B. Shoemaker and A. A. Salyers (J. Bacteriol, 170:1651-1657, 1988) reported that some of these Tcr elements appeared to mediate production of plasmidlike forms, NBU1 and NBU2, from an unlinked region of the chromosome of Bacteroides uniformis 0061. Production of the plasmidlike forms and the transfer frequency of the Tcr elements were both enhanced by preexposure to tetracycline. Thus it appeared that genes involved in production of plasmidlike forms (Plf activity) might be coregulated with transfer genes and that Plf activity might have a role in transfer of the Tcr elements. By screening subclones of a Tcr element, Tcr Emr DOT, we have shown that the genes necessary for Plf activity on the Tcr element are within a 10-kilobase region adjacent to the Tcr gene. Subclones of this region were then used to construct insertional gene disruptions in a Tcr element, Tcr ERL, which is closely related to the Tcr Emr DOT element. Two of the disruption mutants were Plf-. Both had reduced transfer frequencies, one (omega RDB2) 10(2)-fold lower than that of the wild-type element and the other (omega RDBT) 10(4)-fold lower. omega RDB2 was also deficient in the ability to mobilize coresident plasmids, whereas omega RDBT exhibited nearly wild-type mobilization activity. The phenotypes of the mutants indicate that there are at least two genes necessary for Plf activity and that both may be involved in transfer of the element. The third disruption mutant (omegaRDB1), which expressed Plf constitutively, also had a transfer frequency 10(2) -fold lower than that of the wild-type element and was deficient in mobilization of coresident plasmids. The relationship between Plf genes and transfer, therefore, appears to be a complex one.