Biomedical subjects

Michelle Alvarez

Publications and source records attributed to Michelle Alvarez.

3 recordsLinked to original sources

PubMed2006

The identification of newborns using messenger RNA profiling analysis.

The ability to determine the physical characteristics of an individual depositing a bloodstain at a crime scene would be an invaluable tool to investigators, akin to eyewitness information. One useful biometric that may be amenable to molecular genetic analysis is the biological age of an individual. In theory, it may be possible to determine patterns of gene expression that are age specific, thereby permitting the distinction among tissue samples originating from individuals of different ages (e.g., newborn, adolescent, middle-age, elderly). We have discovered two novel isoforms of gamma hemoglobin messenger RNA, designated HBG1n and HBG2n, which exhibit an extremely restricted pattern of gene expression, being confined to newborn individuals. Multiplex quantitative reverse transcription PCR (qRT-PCR) assays incorporating these novel mRNAs have been designed, tested, and evaluated for their potential forensic use. The results indicate that the assays provide the ability to determine whether a bloodstain originated from a newborn.

Aging↗

PubMed2005

Cytokine-driven cell cycling is mediated through Cdc25A.

Lymphocytes are the central mediators of the immune response, requiring cytokines for survival and proliferation. Survival signaling targets the Bcl-2 family of apoptotic mediators, however, the pathway for the cytokine-driven proliferation of lymphocytes is poorly understood. Here we show that cytokine-induced cell cycle progression is not solely dependent on the synthesis of cyclin-dependent kinases (Cdks) or cyclins. Rather, we observe that in lymphocyte cell lines dependent on interleukin-3 or interleukin-7, or primary lymphocytes dependent on interleukin 7, the phosphatase Cdc25A is the critical mediator of proliferation. Withdrawal of IL-7 or IL-3 from dependent lymphocytes activates the stress kinase, p38 MAPK, which phosphorylates Cdc25A, inducing its degradation. As a result, Cdk/cyclin complexes remain phosphorylated and inactive and cells arrest before the induction of apoptosis. Inhibiting p38 MAPK or expressing a mutant Cdc25A, in which the two p38 MAPK target sites, S75 and S123, are altered, renders cells resistant to cytokine withdrawal, restoring the activity of Cdk/cyclin complexes and driving the cell cycle independent of a growth stimulus.

Animals↗

PubMed2004

An mRNA and DNA co-isolation method for forensic casework samples.

RNA analysis is expected to play an increasingly important role in the area of biomolecular forensic analysis. For example, mRNA expression analysis performed on a total RNA sample isolated from a biological stain may be used to identify the nature of the tissue(s) comprising the stain. Many of the physiological stains encountered at crime scenes involve heterogeneous mixtures of different body fluids (e.g., semen and saliva, semen and vaginal secretions). Separate sampling of these mixed stains from different "geographical" locations of the stains to isolate DNA and RNA could result in a misleading estimate of the ratio of the body fluids present and, in extreme cases, even fail to detect one of the contributors. Thus, a prerequisite for the use of mRNA expression profiling in routine forensic analysis is the ability to co-extract DNA and RNA from the same stain. This article describes an optimized method that was specifically developed to co-extract mRNA and DNA from the same physiological stain and that appears to be sufficiently sensitive and robust for routine forensic use.

DNA↗