Induction of N–malonyl–D–tryptophan by drought stress. Is D–tryptophan the only D–amino acid appeared in wilted leaves?

D-amino acid were searched in wilted tomato leaves. D-Isomers of free amino acids were not revealed by the treatment with L- and D-amino acid oxidases. The noncationic fraction of the extract contained N-malonyl-D-tryptophan and no other N-acylated amino acids. A special search for endogenous N-malonyl-D-phenylalanine gave negative results. Exogenous¹⁴C-malonate was only incorporated in one Chromatographic zone corresponding to N-malonyl-D-tryptophan. It is concluded that drought stress does not induce the appearance of D-amino acids except for D-tryptophan which is accumulated in the malonylated form.     

Methylated DNA/RNA in Body Fluids as Biomarkers for Lung Cancer

DNA/RNA methylation plays an important role in lung cancer initiation and progression. Liquid biopsy makes use of cells, nucleotides and proteins released from tumor cells into body fluids to help with cancer diagnosis and prognosis. Methylation of circulating tumor DNA (ctDNA) has gained increasing attention as biomarkers for lung cancer. Here we briefly introduce the biological basis and detection method of ctDNA methylation, and review various applications of methylated DNA in body fluids in lung cancer screening, diagnosis, prognosis, monitoring and treatment prediction. We also discuss the emerging role of RNA methylation as biomarkers for cancer.     

Effects of quantal content,membrane potential,and cholinoceptor density on the time course of end-plate currents in the rat under during acetylcholinesterase inhibition

The time-course of multiquantal end-plate currents (EPCs) was compared with monoquantal synaptic responses, i.e., miniature end-plate currents (MEPCs), in voltage-clamped rat diaphragm muscle fibers. In the presence of active acetylcholinesterase (AChE), the time constant of the decay of EPCs, that were composed of 25–140 quanta, was 1.2 times greater than that of MEPCs. After inhibition of AChE with armine or proserine the decay of the EPC was longer than the decay of the MEPC by 10–100 times, and unlike the MEPC, in the majority of synapses it could be described by the sum of two (n=34) or three (n=9) exponentials: monoexponential EPCs were noted in only three cases. The nature and duration of the EPC decay depended on its quantal content. After a reduction in the quantal content a three-exponential EPC decay could be successively reduced to a two- and a mono-exponential decay. A ,slow, component of the EPC decay, unlike the MEPC decay, was extremely sensitive to changes in the membrane potential, and extracellular magnesium ion concentration. When the cholinoceptors were irreversibly blocked by -bungarotoxin the MEPC decay accelerated, and the monoexponential EPC decay initially slowed down before accelerating, but even during a profound blockade the open-times of the ion channels were not affected. It therefore appears that during the generation of multiquantal EPCs when AChE is inhibited, not only does the synchronicity of the ion channel opening change, but so do their kinetics, possibly because of ion channel blockade by endogenous acetylcholine.S. V. Kurashov Institute of Medicine, Russian Ministry of Public Health, Kazan. Translated from Neirofiziologiya, Vol. 24, No. 3, pp. 269–279, May–June, 1992.     

Triazavirine supramolecular complexes as modifiers of the peptide oligomeric structure

In this study, we present molecular dynamics simulations of the antiviral drug triazavirine, that affects formation of amyloid-like fibrils of the model peptide (SI). According to our simulations, triazavirine is able to form linear supramolecular structures which can act as shields and prevent interactions between SI monomers. This model, as validated by simulations, provides an adequate explanation of triazavirine’s mechanism of action as it pertains to SI peptide fibril formation.     

Individual and sex variation in the inguinal lymph nodes in man]

Under investigation were the lymph nodes on the anterior surface of the femur in the area of the femural triangle in 96 preparations of lower extremities of corpses of people of either sex in the age from 31 to 82 years. The Gerota's mass was injected into the skin of feet, external genitalia and the skin of the lower part of the anterior wall of the abdomen. It was established that the total amount of the inguinal lymph nodes in men was greater than in women, the size of the superficial nodes in women was greater than of those in men, while the size of profound lymph nodes in men was greater than in women. The amount of the inguinal lymph nodes was proportional to the Skerly's index and the dimensions were inversely proportional to their amount. The amount of inguinal lymph nodes in persons of either sex of a dolichomorphic type of figure was greater than in persons of a brachymorphic type. The dimensions of the nodes in persons of brachymorphic type of figure were predominant.     

Anatomy and topography of external iliac lymph nodes in adults]

The investigation of the external iliac lymph nodes has been performed in 152 preparations of corpses of mature persons of both sex, who died from causes not connected with any disease of the lymphatic system, lower extremities and pelvic organs. The external iliac lymph nodes and their afferent and efferent lymphatic vessels have been revealed by means of interstitial injection of the lower extremities and pelvic organs, as well as by means of direct injection of Gerota mass into the lymphatic vessels. Form, amount, dimensions and topography of common iliac lymph nodes have been studied. Lymphatic vessels, running from certain parts and organs of the body to various subgroups of the external iliac lymph nodes have been described, as well as efferent lymph vessels of these nodes. The external iliac lymph nodes are constant formations; the largest of them--lymph nodes of the lacuna--are nodes of the I step for the lower extremity lymph vessels. In 54% of cases in persons of both sex positive (right-sided) asymmetry has been revealed. Total amount of the iliac lymph nodes prevails in men, while their size is greater in women. The size of these nodes in persons of both sex is greater to the left than to the right. There are connections (in 3% of cases) between the external iliac lymph nodes and aortal and lumbar nodes of the opposite side.     

Structural organization of the human genome: distribution of nucleotides, Alu-repeats and exons in chromosomes 21 and 22]

Analysis of DNA sequences of the human chromosomes 21 and 22 performed using a specially designed MegaGene software allowed us to obtain the following results. Purine and pyrimidine nucleotide residues are unevenly distributed along both chromosomes, displaying maxima and minima (Y waves phi) with a period of about 3 Mbp. Distribution of G + C along both chromosomes has no distinct maxima and minima, however, chromosome 21 contains considerably less G + C than chromosome 22. Both exons and Alu repeats are unevenly distributed along chromosome 21: they are scarce in its left part and abundant in the right part, while MIR elements are quite monotonously spread along this chromosome. The Alu repeats show a wave-like distribution pattern similar for both repeat orientations. The number of the Alu repeats of opposite orientations was equal for both studied chromosomes, and this may be considered a new property of the human genome. The positive correlation between the exon and Alu distribution patterns along the chromosome, the concurrent distribution of Alu repeats in both orientations along the chromosome, and the equal copy numbers for Alu in direct and inverted orientations within an individual chromosome point to their important role in the human genome, and do not fit the notion that Alu repeats belong to parasitic (junk) DNA.     

Age and variability in the inguinal lymph nodes of adult humans]

Lymphatic nodes on the anterior surface of the femur, in the region of the femoral triangle were studied in 56 corpses of humans of either sex from 31 to 82 years of age, dead of accidental causes or of diseases not related to lymphatic nodes. The investigation was carried on by the method of interstitial and direct injection of the Gerota's mass to some regions of foot skin, external genitalia and the skin of the anterior wall of the abdomen. It has been established that the size of inguinal lymphatic nodes (both superficial and profound) in humans of either sex, are in direct dependence on the age of the person. The amount of inguinal lymphatic nodes in young people prevails over that in old people. The external diameter of the afferent and efferent vessels in elderly humans is greater than in young ones. The amount of afferent lymphatic vessels to inguinal lymphatic nodes in most cases prevails over the amount of efferent ones, independent of age and sex. The external diameter of the former is greater than that of the latter.