ABSTRACT
The Medical Information Department of a pharmaceutical manufacturer provides written scientific responses to unsolicited requests from healthcare providers for information on products that extends beyond the product labeling (off-label). These scientific response documents are non-promotional, evidence-based, and scientifically balanced, conforming with internal pharmaceutical manufacturer's procedures and the Food and Drug Administration (FDA) Draft Guidance on Responding to Unsolicited Requests for Off-Label Information. Members of phactMI™ developed this proposal to offer best practices for content generation of scientific response documents. Scientific response documents review available literature to respond to an unsolicited request; therefore, they are similar in nature to systematic reviews. The sections and elements identified in this proposed best practice guidelines for scientific response documents are based on an adaptation of the sections and elements of systematic reviews. The sections of a scientific response document should include a restatement of the unsolicited request (title); a structured summary (abstract); approved indications, black box warnings, and background information when appropriate (introduction); the literature search information and study selection (methods); summation of data from clinical trials, meta-analysis, case reports, and/or real world evidence, as appropriate (results); treatment guidelines, if applicable and available (discussion); and references. Elements for each section should be included in a scientific response document as appropriate, as some elements are not necessary in some documents, based on the question. These elements were selected for inclusion to address any potential concerns of bias and transparency and reflect the intent that scientific response documents should be non-promotional, accurate, truthful, free of commercial bias, scientifically balanced, and evidence based.
Subject(s)
Pharmaceutical Preparations , Consensus , Health Personnel , HumansABSTRACT
Polycyclic aromatic hydrocarbons (PAHs), like benzo[a]pyrene (BaP), are ubiquitous environmental pollutants formed by the incomplete combustion of organic materials. The tripeptide glutathione (GSH) is a major antioxidant and is important in detoxification of PAH metabolites. Mice null for the modifier subunit of glutamate cysteine ligase (Gclm), the rate-limiting enzyme in GSH synthesis, have decreased GSH concentrations. We investigated the effects of Gclm deletion alone on male fertility and spermatogenesis and its effect on the sensitivity of male embryos to the transplacental testicular toxicity of BaP. Gclm-/- males had dramatically decreased testicular and epididymal GCL enzymatic activity and total GSH concentrations compared with Gclm+/+ littermates. Ratios of reduced to oxidized GSH were significantly increased in Gclm-/- testes. GSH reductase enzymatic activity was increased in Gclm-/- epididymides. We observed no changes in fertility, testicular weights, testicular sperm head counts, or testicular histology and subtle changes in cauda epididymal sperm counts, motility, and morphology in Gclm-/- compared with Gclm+/+ males. Prenatal exposure to BaP from gestational day 7 to 16 was dose dependently associated with significantly decreased testicular and epididymal weights, testicular and epididymal sperm counts, and with vacuolated seminiferous tubules at 10 weeks of age. Gclm-/- males exposed prenatally to BaP had greater decreases in testicular weights, testicular sperm head counts, epididymal sperm counts, and epididymal sperm motility than Gclm+/+ littermates. These results show no effects of Gclm deletion alone on male fertility and testicular spermatogenesis and subtle epididymal effects but support increased sensitivity of Gclm-/- males to the transplacental testicular toxicity of BaP.
Subject(s)
Benzo(a)pyrene/toxicity , Environmental Pollutants/toxicity , Glutamate-Cysteine Ligase/metabolism , Prenatal Exposure Delayed Effects , Spermatogenesis/drug effects , Testis/drug effects , Animals , Benzo(a)pyrene/administration & dosage , Dose-Response Relationship, Drug , Environmental Pollutants/administration & dosage , Epididymis/drug effects , Epididymis/metabolism , Epididymis/pathology , Female , Glutamate-Cysteine Ligase/genetics , Glutathione/metabolism , Glutathione Reductase/metabolism , Male , Mice , Mice, 129 Strain , Mice, Inbred C57BL , Mice, Knockout , Organ Size/drug effects , Oxidation-Reduction , Oxidative Stress/drug effects , Pregnancy , Spermatozoa/drug effects , Spermatozoa/pathology , Testis/metabolism , Testis/pathologyABSTRACT
Oxidative stress occurs when generation of reactive oxygen species (ROS) overwhelms antioxidant defenses. Oxidative stress has been associated with male infertility. The transcription factor nuclear factor-erythroid 2-related factor 2 (NRF2) regulates basal and inducible transcription of genes encoding enzymes important for protection against ROS. We hypothesized that deletion of the Nrf2 gene causes testicular and epididymal oxidative stress, which disrupts spermatogenesis. Our results show that male Nrf2(-/-) mice have decreased fertility compared to wild-type and heterozygous littermates, due to accumulating seminiferous tubule damage with increasing age. Testicular sperm head counts, epididymal sperm counts, and epididymal sperm motility in 2-month-old Nrf2(-/-) males did not differ from those of wild-type littermates; however, by age 6 months, Nrf2(-/-) males had 44% lower testicular sperm head counts, 65% lower epididymal sperm counts, and 66% lower epididymal sperm motility than wild-type males. Two- to 4-month-old Nrf2(-/-) males had elevated levels of testicular and epididymal lipid peroxidation and testicular germ cell apoptosis, and decreased levels of antioxidants, compared to wild-type males. These results provide evidence that oxidative stress has deleterious effects on the testis and epididymis and demonstrate a critical role for the transcription factor NRF2 in preventing oxidative disruption of spermatogenesis.
