Predictive Modeling of Tacrolimus Dose Requirement Based on High‐Throughput Genetic Screening

Any biochemical reaction underlying drug metabolism depends on individual gene–drug interactions and on groups of genes interacting together. Based on a high‐throughput genetic approach, we sought to identify a set of covariant single‐nucleotide polymorphisms predictive of interindividual tacrolimus (Tac) dose requirement variability. Tac blood concentrations (Tac C₀) of 229 kidney transplant recipients were repeatedly monitored after transplantation over 3 mo. Given the high dimension of the genomic data in comparison to the low number of observations and the high multicolinearity among the variables (gene variants), we developed an original predictive approach that integrates an ensemble variable‐selection strategy to reinforce the stability of the variable‐selection process and multivariate modeling. Our predictive models explained up to 70% of total variability in Tac C₀ per dose with a maximum of 44 gene variants (p‐value <0.001 with a permutation test). These models included molecular networks of drug metabolism with oxidoreductase activities and the multidrug‐resistant ABCC8 transporter, which was found in the most stringent model. Finally, we identified an intronic variant of the gene encoding SLC28A3, a drug transporter, as a key gene involved in Tac metabolism, and we confirmed it in an independent validation cohort.     

Histopathologic and Microbiologic Aspects of Ventilator-associated Pneumonia

Background: The relationship between microbiology and histology in patients with ventilator-associated pneumonia has been sparsely described.

Methods: Twenty-five patients who died in the intensive care unit after their lungs had been mechanically ventilated for 72 h were studied. Twenty of the 25 died with clinical suspicion of pulmonary infection. A total of 375 immediate postmortem pulmonary biopsies were obtained after death and processed for quantitative microbiology and histology. Four evolutionary stages of pneumonia were defined: early, intermediate, advanced, and resolution.

Results: At least one specimen with histologic evidence of pneumonia was found in all but two patients (92%). Histologic pneumonia was a widespread and frequent process (46% of biopsies examined) involving predominantly the lower lobes (55% of all biopsies with pneumonia) and showing different histopathologic stages of progression coexisting in the same lung lobes. Lung cultures were frequently polymicrobial (149 of 375, 40% of the pulmonary biopsy cultures, and 20 of 25, 80% of the cases) and not always yielding the same pathogen (19 microorganisms) when comparing one lung to the other. Histopathology and microbiologic biopsy cultures showed a weak relationship (28% and 49% of species had counts greater or equal to 103 cfu/g in samples without pneumonia from patients with and without prior antibiotic treatment, respectively). Histopathologic evolutionary stages were not associated with any differences in quantitative culture results of pulmonary biopsies, independently of prior administration of antibiotics. Higher bacterial concentrations of biopsy cultures were associated with the absence of prior antibiotic treatment.     

A Study of Incidence and Characteristics of Infections in 476 Patients from a Single Center Undergoing Autologous Blood Stem Cell Transplantation

Infectious complications are a major cause of morbidity and mortality in patients who undergo autologous stem cell transplantation (ASCT). We examined 476 patients with hematologic malignancies (401) or solid tumors (75) who underwent ASCT between February 1990 and May 2005. Anti-infectious prophylaxis consisted of different combinations of ciprofloxacin, cotrimoxazole, fluconazole, aerosolized amphotericin B, acyclovir, and intravenous immunoglobulins. Overall, 454 patients (95%) developed fever in the first 60 days after ASCT. In the majority of patients, initial antibiotic therapy consisted of broad-spectrum beta-lactamic with or without amikacin. A glycopeptide was administered as initial therapy in 86 cases. Overall, there were 132 (29%) clinically documented infections (37 pneumonias), 79 (17%) microbiologically documented infections (65 bacteremias), and 243 (54%) fevers of unknown origin. Coagulase-negative staphylococci (18, 25%) and E coli (18, 25%) were the organisms most frequently isolated. The pattern of infection did not change throughout the study except for a significantly higher incidence of bacteremia due to gram-positive bacteria in the first 5 years of the study. Infection-related mortality was 5% (21 cases), with pneumonia the most frequent cause of death. ASCT should be considered a low-risk procedure, although new therapeutic approaches for patients developing severe respiratory infections are still needed.     

Non‐invasive management of non‐melanoma skin cancer in patients with cancer predisposition genodermatosis: a role for confocal microscopy and photodynamic therapy

Background Patients with genodermatosis such as Gorlin syndrome (GS) and Xeroderma pigmentosum (XP) require a close follow‐up for early diagnosis and treatment of skin cancer. We aimed to evaluate the efficacy of methyl‐aminolevulinate (MAL) photodynamic therapy (PDT) in basal cell carcinomas (BCCs) from patients with GS and XP, and to determine the utility of reflectance confocal microscopy (RCM) in the diagnosis and the evaluation of therapeutic response. Patients and methods We included four patients with GS and two siblings with XP. Single or multiple lesions in localized areas were treated with 1–3 cycles of MAL PDT. RCM was performed before and 3 months after the treatment in target lesions in all the patients. Patients were followed up for 3 years. Results In XP patients, we treated 13 pigmented BCCs on the face. All the lesions responded to the treatment and six lesions showed a complete clinical clearing. In GS patients, facial or trunk areas with multiple BCCs were treated (up to 200). Complete clinical remission was obtained in 25–67% of the lesions. Some nodular and pigmented lesions failed to achieve a complete remission. RCM could identify already described confocal features for BCC. Tumour remissions could be assessed by this technique. Conclusions Methyl‐aminolevulinate PDT may be useful for the treatment of superficial BCC in GS and XP. In some nodular lesions, PDT may complement surgery reducing tumour size. RCM may be regarded in the future as a complementary technique in BCC for the diagnosis and post‐treatment assessment to non‐invasive therapeutic modalities.