Pneumocystis murina colonization in immunocompetent surfactant protein A deficient mice following environmental exposure.

BACKGROUND: Pneumocystis spp. are opportunistic pathogens that cause pneumonia in immunocompromised humans and animals. Pneumocystis colonization has also been detected in immunocompetent hosts and may exacerbate other pulmonary diseases. Surfactant protein A (SP-A) is an innate host defense molecule and plays a role in the host response to Pneumocystis. METHODS: To analyze the role of SP-A in protecting the immunocompetent host from Pneumocystis colonization, the susceptibility of immunocompetent mice deficient in SP-A (KO) and wild-type (WT) mice to P. murina colonization was analyzed by reverse-transcriptase quantitative PCR (qPCR) and serum antibodies were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS: Detection of P. murina specific serum antibodies in immunocompetent WT and KO mice indicated that the both strains of mice had been exposed to P. murina within the animal facility. However, P. murina mRNA was only detected by qPCR in the lungs of the KO mice. The incidence and level of the mRNA expression peaked at 8-10 weeks and declined to undetectable levels by 16-18 weeks. When the mice were immunosuppressed, P. murina cyst forms were also only detected in KO mice. P. murina mRNA was detected in SCID mice that had been exposed to KO mice, demonstrating that the immunocompetent KO mice are capable of transmitting the infection to immunodeficient mice. The pulmonary cellular response appeared to be responsible for the clearance of the colonization. More CD4+ and CD8+ T-cells were recovered from the lungs of immunocompetent KO mice than from WT mice, and the colonization in KO mice depleted CD4+ cells was not cleared. CONCLUSION: These data support an important role for SP-A in protecting the immunocompetent host from P. murina colonization, and provide a model to study Pneumocystis colonization acquired via environmental exposure in humans. The results also illustrate the difficulties in keeping mice from exposure to P. murina even when housed under barrier conditions.

Use pattern and off-label use of atypical antipsychotics in bipolar disorder, 1998-2002.

BACKGROUND: Postmarketing surveillance that identifies patients at high risk for receiving off-label medications will help ensure that the benefits of such treatment outweigh the risks. Because many off-label uses have little scientific support, tracking the extent to which they occur as well as the particular circumstances under which they occur is important. OBJECTIVE: To describe the drug-use pattern for patients with bipolar disorder, and to identify demographic and clinical factors associated with off-label use of atypical antipsychotics before US Food and Drug Administration approval for this indication. METHODS: Using the PHARMetrics medical claims database, a total of 105,771 adult patients with a diagnosis of bipolar disorder were evaluated during the 5-year (1998-2002) study period. Study drugs included mood stabilizers, antipsychotics, and antidepressants. Off-label use of an atypical antipsychotic was defined as a patient taking olanzapine before March 2000 (when it received an indication for bipolar disorder) or any other atypical antipsychotic during the entire study period. Logistic regression analysis was used to determine the odds ratio of receiving a drug off-label. RESULTS: Utilization of and reimbursement for atypical antipsychotics increased during the 5-year period. Of the 10.5% of patients who took atypical antipsychotics, 7.1% took these drugs off-label. In addition, 11% of patients received lithium, 25% received other anticonvulsants, and 34% received antidepressants. Off-label use of atypical antipsychotics was associated with psychiatry specialist prescribers (odds ratio = 1.52; 95% CI, 1.44-1.59) and certain comorbidities, such as substance abuse (odds ratio = 1.51; 95% CI, 1.38-1.66), anxiety disorder (odds ratio = 1.20; 95% CI, 1.14-1.26), diabetes mellitus (odds ratio = 1.26; 95% CI, 1.16-1.37), cerebral vascular disease (odds ratio = 1.26; 95% CI, 1.10-1.45), and hypertension (odds ratio = 1.12; 95% CI, 1.05-1.20). Over time, there has been an increase in the number of drug therapies, including atypical antipsychotics, used to treat bipolar disorder. CONCLUSION: Because of the significant association found between atypical antipsychotic use and several key comorbidities, it is important for physicians to recognize these associations and weigh the risks and benefits of atypical antipsychotics in their treatment strategies.

Expression of hygromycin phosphotransferase alters virulence of Histoplasma capsulatum.

The Escherichia coli hygromycin phosphotransferase (hph) gene, which confers hygromycin resistance, is commonly used as a dominant selectable marker in genetically modified bacteria, fungi, plants, insects, and mammalian cells. Expression of the hph gene has rarely been reported to induce effects other than those expected. Hygromycin B is the most common dominant selectable marker used in the molecular manipulation of Histoplasma capsulatum in the generation of knockout strains of H. capsulatum or as a marker in mutant strains. hph-expressing organisms appear to have no defect in long-term in vitro growth and survival and have been successfully used to exploit host-parasite interaction in short-term cell culture systems and animal experiments. We introduced the hph gene as a selectable marker together with the gene encoding green fluorescent protein into wild-type strains of H. capsulatum. Infection of mice with hph-expressing H. capsulatum yeast cells at sublethal doses resulted in lethality. The lethality was not attributable to the site of integration of the hph construct into the genomes or to the method of integration and was not H. capsulatum strain related. Death of mice was not caused by altered cytokine profiles or an overwhelming fungal burden. The lethality was dependent on the kinase activity of hygromycin phosphotransferase. These results should raise awareness of the potential detrimental effects of the hph gene.