Study of Heart Rate Variability in Control and Hypertensive Subjects

Autonomic nervous system comprising sympathetic and parasympathetic divisions has important role inregulating the cardiovascular system. Heart rate variability has been shown to give objective assessment ofautonomic function. Peripheral Pulse Analyzer has been used to study heart rate variability in controls andhypertensive subjects for understanding manifestations of hypertension on autonomic activity. Subjects havebeen divided in two age groups; 18-30 years and 31-44 years and variability parameters have been comparedwith respect to gender stratification, age stratification and disease stratification. Statistical analysis hasshown marked reduction in the coefficient of variation for variability parameter expressed as logarithm (to thebase 10) in comparison to raw or average value of the parameter and has yielded higher discriminatorystrength in various stratified groups. Excluding age and gender sensitive parameters, significant differenceis observed in amplitude of low frequency component for lower age group male/female hypertensives andamplitude as well as area of low frequency component for higher age group female hypertensives. Theseobservations are in agreement with similarly targeted previous studies. Higher age group male controls andhypertensives, however, could not be discriminated by variability study probably due to similar changesmanifested by senility and hypertension. Thus amplitude and area of low frequency component in heart ratevariability spectrum is identified as hypertension specific parameter.

Emergence of an unrelated highly aberrant clone in an AML patient at relapse four months after peripheral blood stem cell transplantation.

We report a case of AML-M1 with 5q aberration at diagnosis. The patient was treated with high-dose chemotherapy (HDCT). After remission induction, he received allogenic peripheral blood stem cell transplantation (PBSCT) from an HLA-match donor brother. The successive follow-up conventional cytogenetics investigations in remission after HDCT and PBSCT revealed cytogenetic remission. The most interesting observation in this case is that relapsed marrow revealed the emergence of an entirely new, highly aberrant, unrelated clone with unusual translocations t(6;17)(p23;p11.2),+8,der(8)dup inv(8)(q23qter), t(10;19)(q26;q13.3) 4½ months after PBSCT. Our findings suggest the possibility of a mutagenic effect of HDCT and myeloablative intense chemotherapy before PBSCT that could have induced a genetic lesion in the recipient's genetically unstable stem cells in an environment of immunosuppression. The highly complex nature of the clone and the rapid clonal evolution indicates the possibility of selective pressure with proliferative advantage.

Small but mighty RNA-mediated interference in plants.

RNA silencing is a conserved phenomenon of regulation of gene expression by small RNAs derived from cleavage of double-stranded RNA (dsRNA). The present review deals with three overlapping modes of small RNA-mediated silencing particularly in plants. In case of post-transcriptional gene silencing (PTGS), Dicer, an endonuclease, cleaves dsRNA to produce approximately 21nt-long small interfering RNAs (siRNAs), which guide RISC, another nuclease complex, to destroy specific target mRNAs based on sequence complementarity with the siRNA. Another class of siRNAs of 25nt-long is also produced from dsRNA by Dicer, different from that generates 21nt-long siRNA. These longer siRNAs are probably involved in systemic silencing during PTGS and guide methylation of both DNA and histone, and induce heterochromatinization and consequent transcriptional repression of the targeted gene. Both siRNA-mediated PTGS and epigenetic modification of the genome are considered as defense mechanisms to protect against invading viruses, transposons or aberrantly expressing transgenes. Regulation of expression of endogenous genes is mediated by another class of 21nt-long small RNAs called microRNAs (miRNA). Genes encoding the miRNAs are present either in the intergenic regions, introns or coding regions of the plant genome. Cleavage of a stem-loop precursor transcript called pre-miRNA, by another class of Dicer generates miRNAs, which in association with nuclease complex similar to RISC, if not identical, either degrade target mRNA or cause translational repression. The applications of RNA silencing in functional genomics and crop improvement are discussed.

Genetic transformation of Robinia pseudoacacia by Agrobacterium tumefaciens.

Transgenic Robinia pseudoacacia plants were obtained by Agrobacterium tumefaciens mediated gene transfer. Agrobacterium strain LBA4404 harbouring a binary vector that contained the chimeric neomycin phosphotransferase II (NPTII) and beta-glucuronidase (GUS) genes was co-cultivated with hypocotyl segments of in vitro raised seedlings of Robinia. Parameters important for high efficiency regeneration and transformation rates included type of explant, pre-conditioning of explants and appropriate length of co-cultivation period with Agrobacterium. A transformation frequency 16.67% was obtained by 48 hr of pre-conditioning followed by 48 hr of co-cultivation. Transformed tissue was selected by the ability to grow on kanamycin containing medium. Successful regeneration was followed after histochemical GUS assay for the detection of transgenic tissue. This transformation procedure has the potential to expand the range of genetic variation in Robinia.