Hypokalemia from beta2-receptor stimulation by circulating epinephrine

To determine whether epinephrine-induced hypokalemia is due to beta2-adrenoceptor stimulation, and whether hypokalemia can occur at physiologic concentrations of the agonist, epinephrine was infused into six normal volunteers at a rate of 0.1 microgram per kilogram of body weight per minute. The circulating epinephrine concentration was increased to 1.74 +/- 0.65 ng per milliliter, plasma potassium was reduced by 0.82 +/- 0.19 meq per liter, plasma insulin fell by 12 +/- 4 mU per liter, plasma renin activity was elevated, and tachycardia occurred. Isoproterenol infused at 0.02 micrograms per kilogram per minute caused similar tachycardia (25 beats per minute) and elevation in plasma renin activity (6.0 to 6.5 ng per milliliter per hour), but no hypokalemia. The difference in responses to the two catecholamines was ascribed to the relative beta2-selectivity of epinephrine. This hypothesis was tested in six subjects given infusions of epinephrine (0.05 micrograms per kilogram per minute) after administration of either 2.5 or 5 mg of ICI 118551--a selective beta2-receptor antagonist--or placebo. After placebo, epinephrine infusion elevated the circulating epinephrine concentration and reduced plasma potassium; hypokalemia was prevented by the beta2-antagonist. This drug only partially inhibited the rises in plasma renin and glucose and the shortening of systolic time intervals; there was no tachycardia. Fifteen-fold to 30-fold increases in circulating epinephrine concentration appear to cause hypokalemia by a specific beta2-receptor effect distinct from other actions of epinephrine. This phenomenon may be of physiologic importance after severe myocardial infarction, when similar increases in plasma epinephrine have occurred.     

Isolation of hybridoma cell lines and characterization of monoclonal antibodies against cholera enterotoxin and its subunits.

Hybridoma cell lines which produced monoclonal antibodies against cholera toxin were isolated. These cell lines were detected with an enzyme-linked immunosorbent assay screening procedure with purified cholera toxin or subunit A of cholera toxin. Seven cell lines were characterized with respect to their reactivity with cholera toxin subunits by Western blot analysis. Five clones produced antibodies which were directed against subunit A, and two clones produced antibodies which reacted with subunit B. These antibodies were also characterized by Western blot analysis for reactivity with the heat-labile enterotoxin produced by porcine and human enterotoxinogenic strains of Escherichia coli. Monoclonal antibodies which reacted with subunit A of cholera toxin also reacted with subunit A of both porcine and human heat-labile enterotoxins. In contrast, monoclonal antibodies to subunit B of cholera toxin did not react with subunit B of the heat-labile enterotoxin. Antibodies directed against subunit B neutralized the biological activity of cholera toxin in vitro in the S49 mouse lymphosarcoma assay. In contrast to polyclonal anti-subunit A antisera, monoclonal anti-subunit A from four of five clones had small but measurable neutralizing capacities in vitro.     

Lifestyle Risk Score: handling missingness of individual lifestyle components in meta-analysis of gene-by-lifestyle interactions

Recent studies consider lifestyle risk score (LRS), an aggregation of multiple lifestyle exposures, in identifying association of gene-lifestyle interaction with disease traits. However, not all cohorts have data on all lifestyle factors, leading to increased heterogeneity in the environmental exposure in collaborative meta-analyses. We compared and evaluated four approaches (Naïve, Safe, Complete and Moderator Approaches) to handle the missingness in LRS-stratified meta-analyses under various scenarios. Compared to “benchmark” results with all lifestyle factors available for all cohorts, the Complete Approach, which included only cohorts with all lifestyle components, was underpowered due to lower sample size, and the Naïve Approach, which utilized all available data and ignored the missingness, was slightly inflated. The Safe Approach, which used all data in LRS-exposed group and only included cohorts with all lifestyle factors available in the LRS-unexposed group, and the Moderator Approach, which handled missingness via moderator meta-regression, were both slightly conservative and yielded almost identical p values. We also evaluated the performance of the Safe Approach under different scenarios. We observed that the larger the proportion of cohorts without missingness included, the more accurate the results compared to “benchmark” results. In conclusion, we generally recommend the Safe Approach, a straightforward and non-inflated approach, to handle heterogeneity among cohorts in the LRS based genome-wide interaction meta-analyses.Subject terms: Genetics, Risk factors     

Real-time PCR assay for detection of fluoroquinolone resistance associated with grlA mutations in Staphylococcus aureus

Resistance to fluoroquinolones among clinical isolates of Staphylococcus aureus has become a clinical problem. Therefore, a rapid method to identify S. aureus and its susceptibility to fluoroquinolones could provide clinicians with a useful tool for the appropriate use of these antimicrobial agents in the health care settings. In this study, we developed a rapid real-time PCR assay for the detection of S. aureus and mutations at codons Ser-80 and Glu-84 of the grlA gene encoding the DNA topoisomerase IV, which are associated with decreased susceptibility to fluoroquinolones. The detection limit of the assay was 10 genome copies per reaction. The PCR assay was negative with DNA from all 26 non-S. aureus bacterial species tested. A total of 85 S. aureus isolates with various levels of fluoroquinolone resistance was tested with the PCR assay. The PCR assay correctly identified 100% of the S. aureus isolates tested compared to conventional culture methods. The correlation between the MICs of ciprofloxacin, levofloxacin, and gatifloxacin and the PCR results was 98.8%. The total time required for the identification of S. aureus and determination of its susceptibility to fluoroquinolones was about 45 min, including DNA extraction. This new rapid PCR assay represents a powerful method for the detection of S. aureus and its susceptibility to fluoroquinolones.     

Gamma interferon responses induced by a panel of recombinant and purified mycobacterial antigens in healthy,non-mycobacterium bovis BCG-vaccinated Malawian young adults

We have previously shown that young adults living in a rural area of northern Malawi showed greater gamma interferon (IFN-gamma) responses to purified protein derivatives (PPD) prepared from environmental mycobacteria than to PPD from Mycobacterium tuberculosis. In order to define the mycobacterial species to which individuals living in a rural African population have been exposed and sensitized, we tested T-cell recognition of recombinant and purified antigens from M. tuberculosis (38 kDa, MPT64, and ESAT-6), M. bovis (MPB70), M. bovis BCG (Ag85), and M. leprae (65 kDa, 35 kDa, and 18 kDa) in >600 non-M. bovis BCG-vaccinated young adults in the Karonga District of northern Malawi. IFN-gamma was measured by enzyme-linked immunosorbent assay (ELISA) in day 6 supernatants of diluted whole-blood cultures. The recombinant M. leprae 35-kDa and 18-kDa and purified native M. bovis BCG Ag85 antigens induced the highest percentages of responders, though both leprosy and bovine tuberculosis are now rare in this population. The M. tuberculosis antigens ESAT-6 and MPT64 and the M. bovis antigen MPB70 induced the lowest percentages of responders. One of the subjects subsequently developed extrapulmonary tuberculosis; this individual had a 15-mm-diameter reaction to the Mantoux test and responded to M. tuberculosis PPD, Ag85, MPT64, and ESAT-6 but not to any of the leprosy antigens. We conclude that in this rural African population, exposure to M. tuberculosis or M. bovis is much less frequent than exposure to environmental mycobacteria such as M. avium, which have antigens homologous to the M. leprae 35-kDa and 18-kDa antigens. M. tuberculosis ESAT-6 showed the strongest association with the size of the Mantoux skin test induration, suggesting that among the three M. tuberculosis antigens tested it provided the best indication of exposure to, or infection with, M. tuberculosis.     

Failure of attenuated temperature-sensitive influenza A (H3N2) virus to induce heterologous interference in humans to parainfluenza type 1 virus.

The present investigation was undertaken to determine if a candidate live vaccine virus, influenza A/Hong Kong/68-ts-1 [E] (H3N2), induced heterologous interference against an interferon-sensitive, wild-type, parainfluenza type 1 challenge virus. The parainfluenza virus was administered 7 days after Hong Kong/68-ts-1 [E] virus infection. The clinical response, daily quantitative virus shedding, interferon production, and serum and nasal wash antibody responses were determined in an experimental group (influenza A virus followed by parainfluenza virus) and 10 volunteers in a control group (parainfluenza virus only). The volunteers were selected on the basis of susceptibility to the two viruses, i.e. serum hemagglutination-inhibition antibody titer of is less than or greater to 1:8 for influenza virus and low nasal wash antibody titer (is less than or greater to 1:8) for parainfluenza virus. Despite a 100% infection rate in the Hong Kong/68-ts-1 [E] vaccinees, no heterologous interference was induced against the parainfluenza type 1 virus challenge.     

Structural control of immunogenicity. II. Antibody synthesis and cellular immunity in response to immunization with mono-epsilon-oligo-L-lysines

A detailed evaluation of the capacity of mono-ε-DNP-oligo-L-lysines to initiate anti-DNP antibody synthesis and a state of delayed hypersensitivity in guinea-pigs is presented. Peptides containing as few as two lysine residues elicit the production of significant amounts of anti-DNP antibody when they are administered as Freund''s complete adjuvant emulsions. Under these immunization conditions, the serum concentration of anti-DNP antibody is dependent on the chain length of the peptide, and on the amount and kind of mycobacteria in the adjuvant; guinea-pigs lacking the PLL gene produce amounts of anti-DNP antibody indistinguishable from that produced by guinea-pigs possessing this gene. On the other hand, when guinea-pigs are immunized with either 1-ε-DNP-tetra-L-lysine or 1-ε-DNP-nona-L-lysine without the use of mycobacterial adjuvant, anti-DNP antibody is produced only by guinea-pigs receiving the nona-L-lysine and only by those animals possessing the PLL gene.Delayed hypersensitivity results from immunizing PLL+ guinea-pigs with mono-ε-DNP-octa and nona-lysines but not from immunization with mono-ε-DNP-hexa-lysine; PLL— animals do not exhibit delayed hypersensitivity to any of these compounds.The data suggest that antibody synthesis to positively charged compounds may proceed as a result of formation of charge complexes with mycobacterial proteins; under such immunization conditions the intrinsic immunogenicity of a compound is more reliably revealed by the induction or elicitation of cellular immune responses. On this basis, a definite discontinuity in the degree of immunogenicity of the mono-ε-DNP-oligo-L-lysines occurs as the peptides are lengthened from six to eight residues.     

Translocation (X;20) involving the inactive X chromosome in a patient with myeloproliferative disorder

We report a patient with an unclassifiable myeloproliferative disorder and the rare t(X;20)(q13;q13.3) as the sole cytogenetic abnormality. The breakpoint on Xq is consistent with other reports of translocations involving the X chromosome with breakpoints that cluster to Xq13 and association with myeloid disorders. Late replication studies demonstrated the inactive X chromosome was involved in this translocation. The critical event in patients with myeloproliferative disease and deletion of 20q appears to be the loss of tumor suppressor genes. This may also be the mechanism in this patient with a potential cryptic deletion associated with the translocation. Alternatively, spreading of X inactivation into the derivative chromosome 20 provides a second mechanism for the loss of function of tumor suppressor genes on 20q. The finding in this patient of t(X;20) together with three others reported in the literature indicates that this may represent a primary non-random abnormality associated with myeloid malignancy, which may take on clinical significance with the accumulation of more cases.     

Analysis of IFN-kappa expression in pathologic skin conditions: downregulation in psoriasis and atopic dermatitis.

Interferon-kappa (IFN-kappa) is a type I IFN expressed by keratinocytes, monocytes and dendritic cells (DCs). In human keratinocytes, it is produced in response to double-stranded RNA (dsRNA) and other IFNs and protects from viral infections. In monocytes and DCs, IFN-kappa induces tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) and inhibits lipopolysaccharide (LPS)-induced IL-12. In this study, we evaluated IFN-kappa expression in skin lesions of patients with common immune-mediated inflammatory disorders using immunohistochemical techniques. IFN-kappa was not detectable in healthy skin but was strongly expressed in allergic contact dermatitis and lichen planus-affected skin. IFN-kappa was localized mainly in basal and suprabasal keratinocytes and in some leukocytes infiltrating the dermis. In contrast, IFN-kappa expression in psoriatic or atopic dermatitis (AD) pidermis was weak and detectable in only 2 of 5 patients examined. Consistently, cultured keratinocytes and monocytes obtained from psoriatic and AD patients expressed null or low levels of IFN-kappa in response to IFN-gamma, which strongly upregulates IFN-kappa in normal keratinocytes. IFN-kappa accumulated in keratinocyte cytoplasm and plasma membrane, and only limited amounts were released extracellularly. Soluble IFN-kappa did not influence keratinocyte proliferation or chemokine and membrane molecule expression, and only its membrane-associated form activated IFN-stimulated response element (ISRE) signaling. Given the difference in IFN-kappa expression levels in the skin disorders examined, IFN-kappa presence or deficiency might have different pathogenetic consequences depending also on other disease-specific intrinsic alterations.     

A geometric morphometric study of regional differences in the ontogeny of the modern human facial skeleton

This study examines interpopulation variations in the facial skeleton of 10 modern human populations and places these in an ontogenetic perspective. It aims to establish the extent to which the distinctive features of adult representatives of these populations are present in the early post natal period and to what extent population differences in ontogenetic scaling and allometric trajectories contribute to distinct facial forms. The analyses utilize configurations of facial landmarks and are carried out using geometric morphometric methods. The results of this study show that modern human populations can be distinguished based on facial shape alone, irrespective of age or sex, indicating the early presence of differences. Additionally, some populations have statistically distinct facial ontogenetic trajectories that lead to the development of further differences later in ontogeny. We conclude that population-specific facial morphologies develop principally through distinctions in facial shape probably already present at birth and further accentuated and modified to variable degrees during growth. These findings raise interesting questions regarding the plasticity of facial growth patterns in modern humans. Further, they have important implications in relation to the study of growth in the face of fossil hominins and in relation to the possibility of developing effective discriminant functions for the identification of population affinities of immature facial skeletal material. Such tools would be of value in archaeological, forensic and anthropological applications. The findings of this study underline the need to examine more deeply, and in more detail, the ontogenetic basis of other causes of craniometric variation, such as sexual dimorphism and hominin species differentiation.