بایگانی برچسب برای: Human

Innate.Antiviral.Immunity.Methods.and.Protocols.[taliem.ir]

Innate Antiviral Immunity

The symbiosis between humans and viruses has allowed human tropic pathogens to evolve intricate means of modulating the human immune response to ensure its survival among the human population. In doing so, these viruses have developed profound mechanisms that mesh closely with our human biology. The establishment of this intimate relationship has created a species-specific barrier to infection, restricting the virus-associated pathologies to humans. This specificity diminishes the utility of traditional animal models. Humanized mice offer a model unique to all other means of study, providing an in vivo platform for the careful examination of human tropic viruses and their interaction with human cells and tissues. These types of animal models have provided a reliable medium for the study of human-virus interactions, a relationship that could otherwise not be investigated without questionable relevance to humans.
Oxidative.Stress.in.Human.Reproduction.[taliem.ir]

Oxidative Stress in Human Reproduction

Reactive oxygen species (ROS) are highly reactive molecules that are generated from oxygen metabolism. They can be free radicals or non-radicals. Free radicals are molecules that contain at least one unpaired valence electron at their outer shell, making them highly reactive and short lived . Among all the ROS, superoxide anion (•O2-), hydrogen peroxide (H2O2) and hydroxyl radicals (•OH) are the most known examples. Reactive nitrogen species (RNS), is the subclass of ROS that contain nitrogen compound . Both ROS and RNS, when present in physiological amount, have important roles in normal cellular functions such as fghting against infection, regulating different intercellular signaling pathways and facilitating normal maturation and fertilization in reproductive systems . However, when ROS present in high concentration, overwhelming the antioxidant defense system, oxidative stress results, and this may lead to cellular dysfunction via lipid peroxidation, protein and DNA damages . Due to such damaging effect on the cells, OS is related to many pathological conditions including infertility . This chapter introduces concepts of free radicals, redox reactions, and then focuses on ROS, RNS and their sources at cellular levels, particularly in both male and female reproductive systems as well as covering a brief overview of oxidative stress.
Patient-Derived.Xenograft.Models.of.Human.[taliem.ir]

Patient-Derived Xenograft Models of Human Cancer

Given the extensive history of cancer, the history of patient-derived xenograft (PDX) models is also diffcult to fully recapitulate. In particular, this task is complicated by the irregularity with which PDX models were designated. The current use of “PDX cancer models” is a relatively recent addition to the lexicon. However, the general concept of PDX models—i.e., the transplantation of human cancers into animal models—can be found throughout the chronicles of cancer research. However, it wasn’t until the discovery of host immunity and its crucial role in graft survival that the idea of serial transplantation could be realized. Therefore, in order to better reflect the nature of its history, the term “human tumor models” will be used in place of “PDX models,” except when appropriate. Finally, it is important to also mention the existence of the other labels that have been used, including, but not limited to, “human tumor xenografts,” “xenopatients,” heterotransplant tumor models,” “heterotransplanted human tumors,” and “transplantable tumor models.”
Human.Pluripotent.Stem.Cells.[taliem.ir]

Human Pluripotent Stem Cells

Successful execution of any cell‐based project relies on a setting up a robust cell culture laboratory. Guidelines under the Guidance on Good Cell Culture Practice provides an overview of the critical parameters in establishing facilities and training personnel . This is even more important for a stem cell laboratory where primary cells from donor tissue or their derivatives are cultured for extended periods of time. In addition to the safety risks common to most workplaces, such as electrical and fire hazards, a cell culture laboratory has a number of specific hazards associated with handling and manipulating human or animal cells and tissues, as well as toxic ,corrosive or mutagenic solvents and reagents. The most common of these hazards are accidental inoculations with syringe needles or other contaminated sharps, spills and splashes onto skin and mucous membranes, ingestion through mouth pipetting, animal bites and scratches, and inhalation exposures to infectious aerosols .The fundamental objective of any biosafety program is to reduce or eliminate exposure of laboratory workers and the outside environment to potentially harmful biological agents. The most important element of safety in a cell culture laboratory is strict adherence to standard microbiological practices and techniques.
Human.Retrotransposons.in.Health.and.Disease.[taliem.ir]

Human Retrotransposons in Health and Disease

Retrotransposons are a class of mobile genetic elements that make up around 40% of the sequenced mammalian genome (Chinwalla et al. 2002; Lander et al. 2001). Retrotransposons contribute to genomic instability in mammalian genomes by providing interspersed repeats of homologous sequences that can act as substrates for recombination causing deletions, duplications and structural rearrangements in the genome (Romanish et al. 2010). Retrotransposons are thought to be the only active class of mobile genetic element in most mammalian genomes, and can also cause genome instability through jumping to new locations in the genome. These de novo retrotransposon insertions have been reported as the causal mutation in various human genetic diseases (Crichton et al. 2014; Hancks and Kazazian 2012). The copy-and-paste mechanism that retrotransposons use to jump to new locations in the genome involves reverse-transcription of retrotransposon RNA, and integration of the resulting cDNA into new locations in the genome. There are typically a few hundred different types of retrotransposon annotated in each mammalian genome, with each type of retrotransposon being present in up to 10,000 copies. However, the types of retrotransposon, their copy numbers and their genomic locations vary signifcantly between species.