Accurate and reproducible ion mobility measurements for chemical standard evaluation.

Chemical standards are used to calibrate ion mobility spectrometers (IMS) for accurate and precise identification of target compounds. Research over the past 30 years has identified several positive and negative mode compounds that have been used as IMS standards. However, the IMS research community has not come to a consensus on any chemical compound(s) for use as a reference standard. Also, the reported K(0) values for the same compound analyzed on several IMS systems can be inconsistent. In many cases, mobility has not been correlated with a mass identification of an ion. The primary goal of this work was to provide mass-identified mobility (K(0)) values for standards. The results of this work were mass-identified K(0) values for positive and negative mode IMS chemical standards. The negative mode results of this study showed that TNT is a viable negative mode reference standard. New temperature-dependent K(0) values were found by characterizing drift gas temperature and water content; several examples were found of temperature-dependent changes for the ion species of several standards. The overall recommendation of this study is that proposed IMS standards should have temperature-dependent K(0) values quoted in the literature instead of using a single K(0) value for a compound.

Why we should eliminate the due date: a truth in jest.

We currently use flawed calculations to set a woman's due date based on menstrual periods to determine gestational age. We use the estimated gestational age to make management decisions based on our patients' individual needs. This principle is in contrast to our patients' use of dating to set an estimated date of confinement. This date is seen as a very specific point in time. Patients and their families plan on that date and become distressed when the expected date is not met. Given that many patients are induced electively, that many will have their delivery dates changed, and that many will have delivery dates adjusted for medical reasons, and most importantly given that dating is inaccurate and unreliable, we propose eliminating the due date. We propose giving patients a calculated assigned week of delivery at 32 weeks. An assigned week of delivery allows for individualization of obstetric care based on the needs of our patients, their support systems, and hospital staffing. We believe an assigned week of delivery will improve obstetric practice and patient satisfaction.

Group A streptococcal appendicitis in a patient with AIDS.

A man with AIDS developed appendicitis and bacteremia caused by Group A streptococcus, neither of which is considered an opportunistic infection. Group A streptococcus is rarely implicated in appendicitis in children and has not previously been reported in an adult. Immunodeficiency might have predisposed the patient to this unusual infection.

Inhibition of poly(ADP-ribose) polymerase preserves surfactant synthesis after hydrogen peroxide exposure.

Exposure to hydrogen peroxide (H2O2) decreases phosphatidylcholine (PC) synthesis in rabbit type II pneumocytes. Activation of poly(ADP-ribose) polymerase (PARP) may play a role in this process. Exposure of type II pneumocytes to H2O2 resulted in a 53% decrease in the rate of incorporation of [3H]choline into PC (P < 0.001). Cell NAD and ATP levels were decreased by 52% (P < 0.001) and 39% (P < 0.01), respectively, without significant changes in cell viability. Exposure to H2O2 also resulted in a 52% (P < 0.05) increase in the activity of PARP. Preincubation of type II cells with inhibitors of PARP (nicotinamide; 3-aminobenzamide) before H2O2 exposure prevented the increase in PARP activity, and blocked the decreases in ATP, NAD, and rate of PC synthesis. These results suggest that the energy depletion associated with activation of PARP contributes to the effects of oxidant stress on type II cell metabolic function and may be ameliorated by pharmacological agents in vitro.

Adenovirus E3 14.7-kilodalton protein, an antagonist of tumor necrosis factor cytolysis, increases the virulence of vaccinia virus in severe combined immunodeficient mice.

The adenovirus (Ad) 14.7-kDa protein, which is called "14.7K," has been shown to function as a general inhibitor of tumor necrosis factor alpha (TNF) cytolysis in tissue culture assays, and the effect of this antagonism on viral pathogenesis in vivo has recently been explored. In infections of immunocompetent BALB/c mice, we have shown previously that Ad type 2 (Ad2) 14.7K, when cloned into a vaccinia virus (VV) vector in combination with the gene for murine TNF, is able to counteract much of the attenuating effect of TNF on VV virulence. In the present study we utilized VV constructs expressing various combinations of Ad 14.7K and TNF in infections of T- and B-cell-deficient C.B-17 severe combined immunodeficient (SCID) mice to determine whether these cells are directly necessary for 14.7K's reversal of TNF-mediated viral attenuation. The mice were infected by the intranasal route, and mortality, morbidity, histopathology, and virus replication in selected organs were evaluated at various times after infection. We found that, in the SCID murine pneumonia model, neither the attenuation by TNF nor its reversal by Ad 14.7K require the participation of T or B lymphocytes or their secreted products. SCID mice infected with VV expressing both 14.7K and TNF [VV 14.7(+)/TNF] were generally well clinically for the first 7-10 days after infection; however, they developed a subacute or chronic illness, succumbing to diseminated VV infection at least 3 weeks earlier than mice infected with VV expressing TNF alone [VV 14.7(-)/TNF]. Animals infected with VV 14.7(+)/TNF were shown to have higher initial titers of virus and delayed clearance from the lungs as well as more rapid spread of virus to internal organs than animals infected with VV 14.7(-)/TNF. SCID mice infected intranasally with VV without TNF showed a dramatic increase in acute disease and succumbed within the first 1-2 weeks after infection, independent of Ad 14.7K expression.

Characterization of transgenic mice containing adenovirus early region 3 genomic DNA.

Human adenoviruses (Ad) contain a complex transcription region (E3) which codes for proteins that interact with several arms of the immune system. However, E3 genes are not essential for replication in tissue culture. An E3-encoded 19,000-molecular-weight (19K) glycoprotein (gp19K) binds to the class I major histocompatibility complex (MHC) in the endoplasmic reticulum and prevents MHC transport to the cell surface. Three other E3 proteins are involved in the inhibition of apoptosis by tumor necrosis factor alpha. The entire E3 genomic DNA was utilized to produce transgenic mice to study the effect of the E3 proteins on pathogenesis of various infectious agents and to investigate the in vivo synthesis and processing of the multiple E3 mRNAs and proteins. There was basal expression of the E3 promoter in the thymus, kidneys, uterus, and testes and at all levels of the gastrointestinal tract. In addition, the E3 promoter of the transgene could be activated in some other organs, including the liver, by infection of these animals with an E3-deficient Ad (Ad7001) which contains a functional E1A region. Transactivation in vivo could also be demonstrated by infusion of bacterial lipopolysaccharide. There appeared to be differential ratios of expression between several of the E3 mRNAs in transgenic lung fibroblasts and primary kidney cells cultured from the transgenic animals. This observation suggested that there was differential mRNA splicing that was organ specific. These transgenic animals should provide a useful model for studying the effects of the E3 proteins on the immune system and on diseases affected either by control of MHC or by selected functions of tumor necrosis factor that are inhibitable by Ad E3 proteins.

The adenovirus E3 14.7-kilodalton protein which inhibits cytolysis by tumor necrosis factor increases the virulence of vaccinia virus in a murine pneumonia model.

The 14.7-kilodalton protein (14.7K protein) encoded by the adenovirus (Ad) E3 region inhibits tumor necrosis factor alpha (TNF-alpha)-mediated lysis of cells in tissue culture experiments, but the relevance of this effect in vivo is incompletely understood. To examine the effect of the ability of the Ad 14.7K protein to block TNF lysis upon viral pathogenesis in a murine model, we cloned the 14.7K protein-encoding gene into vaccinia virus (VV), permitting its study in isolation from other Ad E3 immunomodulatory proteins. The gene for murine TNF-alpha was inserted into the same VV containing the 14.7K gene to ensure that each cell infected with the VV recombinant would express both the agonist (TNF) and its antagonist (14.7K). VV was utilized as the vector because it accommodates large and multiple inserts of foreign DNA with faithful, high-level expression of the protein products. In addition, infection of mice with VV induces disease with quantifiable morbidity, mortality, and virus replication. The results of intranasal infections of BALB/c mice with these VV recombinants indicate that the Ad 14.7K protein increases the virulence of VV carrying the TNF-alpha gene by reversing the attenuating effect of TNF-alpha on VV pathogenicity. This was demonstrated by increased mortality, pulmonary pathology, and viral titers in lung tissue following infection with VV coexpressing the 14.7K protein and TNF-alpha, compared with the control virus expressing TNF-alpha alone. These results suggest that the 14.7K protein, which is nonessential for Ad replication in tissue culture, is an immunoregulatory protein which functions in vivo to help counteract the antiviral effects of TNF-alpha.

Muscle and thymus cell-free glucocorticoid receptor systems are different.

The stability of the glucocorticoid receptor population in thymus cytosol prepared in a molybdate containing buffer was examined. Stability was initially assessed by an association time course. Those experiments demonstrated a slow decline in receptor specific binding, beginning at about eight hours of incubation at 4 degrees C. Stability was further assessed with a forward and reverse isotherm. The presence of hysteresis when the forward (association) and reverse (dissociation) isotherms were compared demonstrates that some element of the system either does not reach or does not maintain a stable state. A comparison with studies in muscle indicates that either the receptors or some component(s) of the cell free systems from thymus and muscle are different. Furthermore, equilibrium binding characteristics examined in thymus cytosols prepared in a molybdate buffer may be questionable due to instability in the receptor population.