Increasing trend of Cesarean deliveries in HIV-infected women in the United States from 1994 to 2000

BACKGROUND: Meta-analysis and randomized clinical trial results reported in June 1998 indicated a significant reduction in perinatal HIV transmission rates among mothers undergoing a cesarean section (C-section). OBJECTIVE: The objective of this study was to examine recent trends in and factors associated with C-section deliveries among HIV-infected women in the United States. DESIGN: A multisite pediatric medical record review of a cohort of HIV-exposed and HIV-infected infants in the Pediatric Spectrum of HIV Disease (PSD) Cohort study (n = 6467) and the national Pediatric HIV/AIDS Reporting System (HARS) (n = 8,306) was conducted. SETTING/PATIENTS: All infants born between 1994 and 2000 to HIV-positive mothers referred to the PSD study or to a Pediatric HARS hospital or clinic site were enrolled. RESULTS: The proportion of deliveries by C-section was steady at about 20% from 1994 through June 1998. From July 1998 through December 2000, this proportion increased to 44% in the PSD study and to nearly 50% in the Pediatric HARS. On analysis by multiple logistic regression, delivery of infants by C-section was associated with the release of study results (OR = 2.83), delivery in four PSD sites in reference to Texas (OR: 2.02-1.43), having private medical care reimbursement (OR = 1.62), and having maternal prenatal care (OR = 1.43). CONCLUSIONS: The PSD and Pediatric HARS data demonstrate a sharp increase in C-section rates mainly among HIV-infected women in the United States after the release of the meta-analysis and randomized clinical trial results in 1998. This finding highlights the rapid impact of study results on obstetric practice. It underscores the critical role of prenatal care in offering perinatal interventions such as scheduled C-section when indicated to reduce the likelihood of HIV transmission.     

Entamoeba invadens contains the components of a classical adrenergic signaling system

Epinephrine (Epi) was previously found to bypass the need for galactose ligands during early steps in the initiation of Entamoeba encystment. Epinephrine is presumed to act on amoebae through a classical adrenergic signaling pathway that results in the increased production of cyclic adenosine monophosphate (cAMP). The object of this study was to verify the existence of an adrenergic like pathway and its response to Epi in both whole Entamoeba trophozoites and purified plasma membrane preparations. Whole trophozoite and purified membrane preparations from Entamoeba invadens responded to the presence of Epi by increasing the production of cAMP. The modulators of heterotrimeric G protein signaling, forskolin (FK), pertussis toxin (PTX) and cholera toxin (CTX), also increased cAMP levels in whole cells and membrane fragments. All of these increases in cAMP were inhibited by specific inhibitors of adenylyl cyclase (AC). Treatment of membrane fragments with epinephrine caused an increased binding of non-hydrolysable GTP analogs. Entamoeba trophozoites therefore appear to contain G-protein-regulated adenylyl cyclase that functions downstream of an adrenergic ligand receptor.     

Partially Inverted Tandem Repeat Isolated from Pericentric Region of Chicken Chromosome 8

The majority of chicken repetitive sequence is nuclear-membrane-associated sequence (CNM), which resides in a large number of microchromosomes (chromosomes 11–39) and is absent from macrochromosomes 1–5, ZW, and some of the intermediate chromosomes 6–10. Two repetitive families, EcoRI/XhoI, are confined to the female-specific W chromosome. The core repeat units of the three families are 21 bp, containing (A)_3–5 and (T)_3–5 clusters separated by 5–7-bp sequences. In this article, we describe the isolation and initial characterization of a novel repeat family that is related to CNM/EcoRI/XhoI families. The novel family, designated as PIR, consists of multiple types of partially inverted repeat units of about 1.2, 1.4 and 1.6 kb. The PIR sequence is restricted to chicken chromosome 8, and accounts for about 3.8 mb, or 2500 copies of the 1.4-kb units, of the chicken genome. The evolution of PIR and related sequences is discussed.     

Correlation of penicillin Binding protein 2a detection with oxacillin resistance in Staphylococcus aureus and discovery of a novel penicillin binding protein 2a mutation

We compared a rapid slide latex agglutination test (LAT; Oxoid, Basingstoke, United Kingdom) that detects penicillin binding protein 2a (PBP2a) with MicroScan conventional panels (Dade Behring, West Sacramento, CA) for detection of oxacillin resistance in Staphylococcus aureus. The PBP2a LAT demonstrated 99% agreement with MicroScan oxacillin MIC results for 388 isolates of S. aureus. All 249 oxacillin-resistant isolates gave strong positive reactions in the LAT (100% sensitivity). Three of the 139 oxacillin-susceptible isolates were also strongly positive and one was weakly positive in the LAT (97.1% specificity). The three oxacillin-susceptible isolates with strongly positive reactions were further characterized. The mecA gene was detected in all three by PCR; one isolate was determined to be resistant to oxacillin by reference broth microdilution testing (MIC, 8 microg/ml), one isolate was inducibly resistant to oxacillin (MIC of 16 microg/ml after overnight induction), and one isolate remained susceptible regardless of the method used for testing. Sequence analysis of a 2.1-kb gene fragment of the mecA gene from the susceptible isolate revealed a one-base substitution at nucleotide position 1449 which results in a Met-to-Ile change for amino acid residue 483. This amino acid substitution has not been previously reported and may be associated with a change in the function of PBP2a resulting in oxacillin susceptibility. An additional 487 isolates were tested in parallel with the both the LAT and MicroScan panels using criteria in which only strong (3 to 4+) or repeatedly weak (1 to 2+) LAT reactions were considered positive, and the results showed 99.4% agreement. The PBP2a LAT provided rapid and reliable detection of oxacillin resistance and proved a useful adjunct to the phenotypic method. Both methods provided reliable detection of oxacillin-resistant S. aureus and facilitated the discovery of a novel, functionally impaired form of PBP2a.     

A segment of the Mecp2 promoter is sufficient to drive expression in neurons

Rett syndrome (RTT) is caused by mutations in the gene encoding methyl CpG-binding protein 2 (MeCP2). Although MeCP2 shows widespread expression in both neuronal and non-neuronal tissues, the symptoms of RTT are largely neurological. Herein, we have identified the regulatory region of the mouse Mecp2 gene that is sufficient for its restricted expression in neurons. A segment of the Mecp2 gene (-677/+56) exhibited strong promoter activity in neuronal cell lines and cortical neurons, but was inactive in non-neuronal cells and glia. The region necessary for neuronal-specific promoter activity was located within a 19 bp region (-63/-45). Several nuclear factors were found to bind to this region and some of these factors were enriched in nuclear extracts prepared from the brain. To examine the activity of the Mecp2 promoter in vivo, we generated transgenic mice expressing the LacZ reporter driven by the -677/+56 region of the Mecp2 gene. The transgene was expressed in the mesencephalon as early as embryonic day 10 and in the hindbrain and spinal cord by E12. Interestingly, a marked induction of transgene expression was observed postnatally throughout the brain, similar to that of endogenous MeCP2. However, expression of the transgene was absent in non-neuronal tissues that are known to express Mecp2. Taken together, these data indicate that the -677/+56 region of the Mecp2 promoter partially recapitulates the native expression pattern of the Mecp2 gene, which possesses restricted expression in neurons of the central nervous system.     

Increasingly frequent diagnosis of acute gastrointestinal graft-versus-host disease after allogeneic hematopoietic cell transplantation.

The reported incidence of grades II to IV acute graft-versus-host disease (GVHD) after hematopoietic cell transplantation with HLA-identical sibling donors has increased considerably during the past 15 to 20 years at our center. The purpose of this study was to evaluate the potential reasons for this change. We reviewed organ stages and overall grades of GVHD for 2220 patients who received a first marrow or peripheral blood cell transplant from an HLA-identical sibling or an HLA-allele-matched unrelated donor with the use of a posttransplantation immunosuppressive regimen that included both methotrexate and cyclosporine between 1985 and 2001. The most striking change was an increased incidence of stage 1 gut involvement from 10% to 20% before 1992 to 50% to 60% since 1992, both with related and unrelated donors. This change increased the incidence of grade II GVHD with sibling donors, such that the overall incidence of grade II to IV GVHD is now 60% to 70%. Among patients with chronic myeloid leukemia in chronic phase, the increasingly frequent diagnosis of acute GVHD since 1992 has not been associated with decreased survival. A high diagnostic sensitivity and increased awareness that gut GVHD can occur without skin involvement account for the increased incidence of acute GVHD at our center.     

Truncated immunoglobulin Dmu causes incomplete developmental progression of RAG-deficient pro-B cells.

Early stages of B cell development are dependent on the expression of a pre-B cell receptor (BCR), composed of a mu heavy chain (HC) in association with surrogate light chain (SLC) proteins and the signaling molecules, Igalpha and Igbeta. During the formation of the variable region of the mu chain by somatic gene rearrangement, a truncated form of the mu protein (called Dmu) is sometimes produced by the rearrangement of a D(H) segment to a J(H) segment using one of three reading frames (designated rf2). When a Dmu protein is formed, subsequent B cell development is blocked by down-regulation of further HC rearrangements, so that a full-length muHC cannot be formed. In this study, we demonstrate that in recombinase activating gene (RAG)-2-deficient B220(+) CD43(+) pro-B cells in which B lymphopoiesis has been arrested at fraction C, transgenic expression of Dmu promoted partial developmental progression to fraction C', but was unable to mediate the pro-B to pre-B cell transition to fraction D effected by full-length muHC protein. These data suggest that the intracellular signaling pathways engaged by the Dmu pre-BCR are insufficient to facilitate the expansion and/or survival of pre-B cells, and are distinct from those engaged by the pre-BCR-containing full-length muHC.     

Oral food challenge failures among foods restricted because of atopic dermatitis

Background

Recent studies have suggested that removing foods from the diet to manage atopic dermatitis (AD), based on positive allergy test results, may lead to immediate allergic reactions on reintroduction of that food.

Comparison of six cannabinoid metabolite assays

Numerous methods for the detection of urinary metabolites of marijuana constituents are available. Documentation of the sensitivity and specificity of these tests is needed before the determination of a pair of screening-confirmation tests can be made. This study used 88 clinical specimens to evaluate five commercially available marijuana metabolite methods and one new gas chromatography/mass spectrometry (GC/MS) method. The EMIT-d.a.u. test was found to have 2 to 3% unconfirmed positives when compared to the other methods evaluated. The new thin layer procedure, TOXI-LAB, was not as sensitive as the EMIT-d.a.u. procedure for some specimens, but proved to be a good confirmation for the EMIT-d.a.u. with elimination of all "unconfirmed positives." The Abuscreen (Roche) and the EMIT-st assays were positive for samples that contained larger amounts of 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic acid (11-nor-delta 9-THC-9-COOH). The Immunalysis-radioimmunoassay (RIA) was positive for all samples found positive by the GC/MS method, but the concentrations found by the two assays did not correlate. The GC/MS method was developed to use the same extraction as the thin layer procedure and provides confirmation for all procedures except 2 to 3% of the positive EMIT-d.a.u. results.