Group testing in mediation analysis

We consider the scenario where there is an exposure, multiple biologically defined sets of biomarkers, and an outcome. We propose a new two-step procedure that tests if any of the sets of biomarkers mediate the exposure/outcome relationship, while maintaining a prespecified familywise error rate. The first step of the proposed procedure is a screening step that removes all groups that are unlikely to be strongly associated with both the exposure and the outcome. The second step adapts recent advances in postselection inference to test if there are true mediators in each of the remaining candidate sets. We use simulation to show that this simple two-step procedure has higher statistical power to detect true mediating sets when compared with existing procedures. We then use our two-step procedure to identify a set of Lysine-related metabolites that potentially mediate the known relationship between increased body mass index and the increased risk of estrogen-receptor positive breast cancer in postmenopausal women.     

Alcohol, Osteoporosis, and Bone Regulating Hormones

The mechanism of the production of ethanol-associated osteopenia seems to be a direct effect of alcohol on bone cells and an indirect or modulating effect through mineral regulating hormones such as vitamin D metabolites, parathyroid hormone, and calcitonin. The modulating effects of these hormones on bone and mineral metabolism in acute and chronic alcohol consumption is discussed herein. Key Words: Alcohol, PTH, Calcitonin, Vitamin D, Bone.     

Efficacy and safety of transcranial magnetic stimulation in the acute treatment of major depression: a multisite randomized controlled trial.

BACKGROUND: We tested whether transcranial magnetic stimulation (TMS) over the left dorsolateral prefrontal cortex (DLPFC) is effective and safe in the acute treatment of major depression. METHODS: In a double-blind, multisite study, 301 medication-free patients with major depression who had not benefited from prior treatment were randomized to active (n = 155) or sham TMS (n = 146) conditions. Sessions were conducted five times per week with TMS at 10 pulses/sec, 120% of motor threshold, 3000 pulses/session, for 4-6 weeks. Primary outcome was the symptom score change as assessed at week 4 with the Montgomery-Asberg Depression Rating Scale (MADRS). Secondary outcomes included changes on the 17- and 24-item Hamilton Depression Rating Scale (HAMD) and response and remission rates with the MADRS and HAMD. RESULTS: Active TMS was significantly superior to sham TMS on the MADRS at week 4 (with a post hoc correction for inequality in symptom severity between groups at baseline), as well as on the HAMD17 and HAMD24 scales at weeks 4 and 6. Response rates were significantly higher with active TMS on all three scales at weeks 4 and 6. Remission rates were approximately twofold higher with active TMS at week 6 and significant on the MADRS and HAMD24 scales (but not the HAMD17 scale). Active TMS was well tolerated with a low dropout rate for adverse events (4.5%) that were generally mild and limited to transient scalp discomfort or pain. CONCLUSIONS: Transcranial magnetic stimulation was effective in treating major depression with minimal side effects reported. It offers clinicians a novel alternative for the treatment of this disorder.     

An open-label efficacy pilot study with pimecrolimus cream 1% in adults with facial seborrhoeic dermatitis infected with HIV

BACKGROUND: Seborrhoeic dermatitis (SD) is a common dermatosis in human immunodeficiency virus (HIV)-positive patients, many of whom do not respond satisfactorily to conventional topical treatments such as corticosteroids and antifungals. OBJECTIVE: A pilot study to investigate the efficacy and tolerability of pimecrolimus cream 1% in HIV-positive patients with facial SD. METHODS: In a single-centre study, 21 HIV-infected patients with mild to severe SD were treated twice daily with pimecrolimus cream 1% for 14 days. Thereafter, treatment was discontinued and patients followed up for 5 weeks. Skin involvement at baseline and on days 7, 14, 21, 35 and 49 was assessed using a four-point clinical score and digital photography. MAIN OUTCOME MEASURES: Efficacy and safety of pimecrolimus cream 1% treatment and incidence of relapse in the follow-up phase. Results Marked improvement was seen in clinical parameters at day 7, with >or= 90% patients clear of symptoms at day 14. Relapse was observed at day 35 but signs were milder than at baseline. All patients responded to therapy, despite their immunological status. Pimecrolimus did not alter CD4(+) and CD8(+) T-cell counts or viral load during the treatment period. CONCLUSION: Pimecrolimus cream represents a new, effective therapeutic option for facial SD in HIV patients.     

Food allergy as a risk factor for asthma morbidity in adults.

BACKGROUND: The objective of this study was to evaluate the relationship between food allergy and asthma morbidity in adults. METHODS: We interviewed a cohort of persistent asthmatics from an inner-city clinic. Allergies to food were assessed by patient report of convincing symptoms of acute allergic reactions. Outcome variables included health resource utilization and medication use. RESULTS: The prevalence of allergy to fish, peanut, tree-nut, shellfish, and seed allergies were 3%, 3%, 3%, 13%, and 1%. Patients with allergies to > 1 food had increased asthma hospitalizations, ED visits, and use of oral steroids (p < 0.05 for all comparisons). Specifically, allergy to fish was associated with a greater risk of health resource utilization and increased frequency of oral steroid use (p < or = 0.03 for all comparisons). CONCLUSIONS: Self-reported allergy to foods was associated with worse outcomes, suggesting that food allergy may be a risk factor for increased asthma morbidity in adults.     

Allergenicity of orally administered immunoglobulin preparations in food-allergic children

Passive immunization by the oral administration of immunoglobulin preparations derived from bovine milk, chicken egg, and human sera has been proposed as a method for the prevention and treatment of enteric diseases. However, the allergenic potential of these proteins may be a factor limiting their widespread use for disease prevention. An in vitro study with sera from milk- and egg-allergic children was performed to determine whether these immunoglobulin preparations have allergenic potential. Protein extracts of milk, bovine immunoglobulin, egg white, human immune globulin, and five egg yolk antiviral immunoglobulin preparations were bound to nitrocellulose paper. These preparations were probed for specific IgE binding with sera from milk- and egg-allergic patients. Of 22 milk-hypersensitive patients, 16 had specific IgE binding against the bovine immunoglobulin preparation. Of 28 egg-allergic patients 15 had specific IgE binding against one or more of the egg yolk-derived antiviral chicken immunoglobulins. Control sera were negative against the milk and egg preparations. Western blot analysis confirmed that milk- and egg-allergic patients had IgE-specific antibodies for bovine and chicken immunoglobulin molecules. Therefore, the removal of contaminating proteins from milk and egg antibody preparations would be unlikely to eliminate their allergenic potential. In contrast, sera from milk- and egg-allergic patients displayed no detectable IgE binding to human immunoglobulin preparations. These data indicate that the administration of antibody preparations derived from bovine and chicken sources may lead to severe allergic reactions in milk- or egg-sensitized patients and to sensitization in some nonallergic individuals.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of inhaled prostaglandin D2 in normal and atopic subjects, and of pretreatment with leukotriene D4

BACKGROUND: Prostaglandin (PG) D2 is a potent bronchoconstrictor mediator and is found, together with leukotriene (LT) D4, in bronchoalveolar lavage fluid during the early response to allergen challenge in asthmatic subjects. The potency of PGD2 has not been established in normal and atopic non-asthmatic subjects, nor has the contribution of cholinergic mechanisms to PGD2 induced bronchoconstriction in normal subjects. Mediators released simultaneously may interact, so the effect of pre-inhalation of LTD4 on PGD2 responsiveness was investigated. METHODS: Six normal and six atopic non-asthmatic subjects performed histamine and PGD2 challenges on separate occasions. Eight normal subjects performed PGD2 challenges immediately before and 45 minutes after inhalation of 200 micrograms oxitropium bromide or placebo. Bronchial responsiveness to PGD2 was established in six normal subjects immediately after pretreatment with saline or non-bronchoconstricting doses of methacholine or LTD4 (challenge 1), and again at six hours (challenge 2). All studies were performed in a double blind, randomised, crossover fashion. RESULTS: PGD2 was 25-fold and 18-fold more potent as a bronchoconstrictor than histamine in atopic non-asthmatic and normal subjects, respectively. Responsiveness (PC35sGaw) to histamine and PGD2 correlated significantly (r = 0.917, n = 12, p < 0.001). Oxitropium bromide in a dose of 200 micrograms inhibited PGD2 induced bronchoconstriction by 37.5%, although in two of these subjects no inhibition was seen. Pre- inhalation of LTD4 and methacholine shifted the dose-response curve of PGD2 to the left by 4.6-fold and 2.4-fold, respectively. CONCLUSIONS: PGD2 is a potent bronchoconstrictor in normal subjects, which is partly mediated by cholinergic mechanisms in some subjects. No significant interaction was found between LTD4 and PGD2 in six normal subjects.


     

Interaction between hamartin and tuberin, the TSC1 and TSC2 gene products

Tuberous sclerosis (TSC) is an autosomal dominant disorder caused by a mutation in either the TSC1 or TSC2 tumour suppressor gene. The disease is characterized by a broad phenotypic spectrum that can include seizures, mental retardation, renal dysfunction and dermatological abnormalities. TSC2 encodes tuberin, a putative GTPase activating protein for rap1 and rab5. The TSC1 gene was recently identified and codes for hamartin, a novel protein with no significant homology to tuberin or any other known vertebrate protein. Here, we show that hamartin and tuberin associate physically in vivo and that the interaction is mediated by predicted coiled-coil domains. Our data suggest that hamartin and tuberin function in the same complex rather than in separate pathways.