Informational dynamics of vasomotion in microvascular networks: a review

Vasomotion refers to spontaneous oscillation of small vessels observed in many microvascular beds. It is an intrinsic phenomenon unrelated to cardiac rhythm or neural and hormonal regulation. Vasomotion is found to be particularly prominent under conditions of metabolic stress. In spite of a significant existent literature on vasomotion, its physiological and pathophysiological roles are not clear. It is thought that modulation of vasomotion by vasoactive substances released by metabolizing tissue plays a role in ensuring optimal delivery of nutrients to the tissue. Vasomotion rhythms exhibit a great variety of temporal patterns from regular oscillations to chaos. The nature of vasomotion rhythm is believed to be significant to its function, with chaotic vasomotion offering several physiological advantages over regular, periodic vasomotion. In this article, we emphasize that vasomotion is best understood as a network phenomenon. When there is a local metabolic demand in tissue, an ideal vascular response should extend beyond local microvasculature, with coordinated changes over multiple vascular segments. Mechanisms of information transfer over a vessel network have been discussed in the literature. The microvascular system may be regarded as a network of dynamic elements, interacting, either over the vascular anatomical network via gap junctions, or physiologically by exchange of vasoactive substances. Drawing analogies with spatiotemporal patterns in neuronal networks of central nervous system, we ask if properties like synchronization/desynchronization of vasomotors have special significance to microcirculation. Thus the contemporary literature throws up a novel view of microcirculation as a network that exhibits complex, spatiotemporal and informational dynamics.

Perfusion CT - Can it resolve the pancreatic carcinoma versus mass forming chronic pancreatitis conundrum?

OBJECTIVES

To evaluate the utility of perfusion CT (PCT) in differentiating pancreatic adenocarcinoma from mass forming chronic pancreatitis (MFCP).

METHODS

In this ethically approved study, PCT was performed in 122 patients with pancreatic masses of which 42 patients had pancreatic adenocarcinoma and 13 had MFCP on histopathology. Perfusion parameters studied included blood flow (BF), blood volume (BV), permeability surface area product (PS), time to peak (TTP), peak enhancement intensity (PEI) and mean transit time (MTT). Twenty five controls with no pancreatic pathology were also studied.

RESULTS

Amongst the perfusion parameters BF and BV were found to be the most reliable for differentiating between adenocarcinoma and mass forming pancreatitis. Although they were reduced in both pancreatic adenocarcinoma (BF- 16.6 ± 13.1 ml/100 ml/min and BV- 5 ± 3.5 ml/100 ml) and MFCP (BF- 30.4 ± 8.7 ml/100 ml/min and BV- 8.9 ± 3.1 ml/100 ml) as compared to normal controls (BF- 94.1 ± 24 ml/100 ml/min and BV- 36 ± 10.7 ml/100 ml) but the extent of reduction was greater in pancreatic adenocarcinoma than in MFCP. Based on ROC analysis cut off values of 19.1 ml/100 ml/min for BF and 5 ml/100 ml for BV yielded optimal sensitivity and specificity for differentiating pancreatic adenocarcinoma from MFCP.

CONCLUSIONS

PCT may serve as an additional paradigm for differentiating pancreatic adenocarcinoma from mass forming chronic pancreatitis and a useful tool for detecting masses which are isodense on conventional CT.

A database of thermodynamic quantities for the reactions of glycolysis and the tricarboxylic acid cycle

Analysis of biochemical systems requires reliable and self-consistent databases of thermodynamic properties for biochemical reactions. Here a database of thermodynamic properties for the reactions of glycolysis and the tricarboxylic acid cycle is developed from measured equilibrium data. Species-level free energies of formation are estimated on the basis of comparing thermodynamic model predictions for reaction-level equilibrium constants to previously reported data obtained under different experimental conditions. Matching model predictions to the data involves applying state corrections for ionic strength, pH, and metal ion binding for each input experimental biochemical measurement. By archiving all of the raw data, documenting all model assumptions and calculations, and making the computer package and data available, this work provides a framework for extension and refinement by adding to the underlying raw experimental data in the database and/or refining the underlying model assumptions. Thus the resulting database is a refinement of preexisting databases of thermodynamics in terms of reliability, self-consistency, transparency, and extensibility.

Meal scheduling modulation of circadian rhythm of phototactic behaviour in cave dwelling fish

Phototactic responses of three groups, each of 16 cave fishes, were observed at 4-hr intervals beginning at 0900, following 5 days of acclimation inside specially designed aquaria. The latter consisted of two parts, a photic zone and an aphotic zone. The first group of fishes were fed ad libitum, while the second and third group of fishes were fed with minced mutton and/or liver delivered in the photic zone between 0700-1100, and in the aphotic zone between 1900-2100. The percentage of fishes present in the photic zone at a given time was used as a measure of their phototactic responses. Single cosinor analysis of these data has revealed, for the first time, a circadian rhythmicity in the phototactic behaviour of a cavernicolous organism. However, imposition of restricted feeding schedules shifted the peak time of the circadian rhythm in phototactic responses. Meal scheduling may thus be an effective synchronizer for this behavioural rhythm.

Transposons: Unexpected players in cancer

Transposons are repetitive DNA sequences encompassing about half of the human genome. They play a vital role in genome stability maintenance and contribute to genomic diversity and evolution. Their activity is regulated by various mechanisms considering the deleterious effects of these mobile elements. Various genetic risk factors and environmental stress conditions affect the regulatory pathways causing alteration of transposon expression. Our knowledge of the biological role of transposons is limited especially in various types of cancers. Retrotransposons of different types (LTR-retrotransposons, LINEs and SINEs) regulate a plethora of genes that have a role in cell reprogramming, tumor suppression, cell cycle, apoptosis, cell adhesion and migration, and DNA repair. The regulatory mechanisms of transposons, their deregulation and different mechanisms underlying transposon-mediated carcinogenesis in humans focusing on the three most prevalent types, lung, breast and colorectal cancers, were reviewed. The modes of regulation employed include alternative splicing, deletion, insertion, duplication in genes and promoters resulting in upregulation, downregulation or silencing of genes.

Influence of human urinary erythropoietin and L-thyroxine on blood morphology and energy reserves in two tropical species of fed and starved teleosts

Erythropoietic responses of fed and starved species of teleosts, viz., Clarias batrachus and Heteropneustes fossilis, to human urinary erythropoietin and thyroxine have been examined. The effects of these hormones on energy reserves have also been evaluated. Twenty-four C. batrachus were divided into two groups: half were fed regularly; the remaining fish were starved 20 days. On the 21st day each group was further divided into three subgroups of four each and received either saline, thyroxine (8 micrograms), or erythropoietin (6 IU) over 4 consecutive days. The experimental protocol was identical for H. fossilis; however, for H. fossilis two identical studies were conducted approximately 1 year apart. A decline in the rate of erythropoiesis and a stimulatory response to human urinary erythropoietin followed starvation in both species of teleosts. In addition, erythropoietin had a pronounced effect on hepatic glycogenesis of fed H. fossilis and stimulated erythropoiesis in the fed teleosts of both species. Prolonged starvation drastically depleted hepatic glycogen in C. batrachus. In contrast, it had no effect on hepatic glycogen in H. fossilis and on muscle glycogen and protein in both species. In general, while both species could respond to erythropoietin and withstand prolonged starvation, H. fossilis alone exhibited remarkable tolerance to fasting.

Biochemical characterization of a high affinity phosphate transporter (PiPT) from root endophyte fungus Piriformospora indica

We have functionally characterized the high-affinity phosphate transporter (PiPT) from the root endophyte fungus Piriformospora indica. PiPT belongs to the major facilitator superfamily (MFS). PiPT protein was purified by affinity chromatography (Ni-NTA) and Size Exclusion Chromatography (SEC). The functionality of solubilized PiPT was determined in detergent-solubilized state by fluorescence quenching and in proteoliposomes. In the fluorescence quenching assay, PiPT exhibited a saturation concentration of approximately 2 μM, at a pH of 4.5. Proteoliposomes of size 121.6 nm radius, showed transportation of radioactive phosphate. Vmax was measured to be 232.2 ± 11 pmol/min/mg protein. We have found Km to be 45.8 ± 6.2 μM suggesting high affinity towards phosphate.

New observations of the endangered giant freshwater whipray, Urogymnus polylepis, provide further evidence for its distribution and breeding in the north-east coast of India

The present study reports observations of 13 giant freshwater whipray (Urogymnus polylepis) from commercial fish landings along the north-east coast of India and updates existing records based on field observations and local social media reports. The disc width of the landed specimens ranged from 120 to 223 cm and they weighed 95-300 kg. All 13 specimens observed were mature (nine females and four males) and three females were pregnant, with embryo numbers ranging between 4 and 15. Globally, U. polylepis is listed as 'Endangered', and greater protection measures are needed in India to assist in reversing current population declines.

Comparative study of rice-based oral rehydration salt solution versus glucose-based oral rehydration salt solution (WHO) in children with acute dehydrating diarrhoea

One hundred children with acute dehydrating diarrhoea were studied. They were divided into two groups: Group A (n = 50) were given rice-based oral rehydration salt (ORS) solution and group B (n = 50) were given glucose-based ORS solution (WHO). There was no significant decrease in mean stool output and percentage weight gain with rice-based ORS. Both the groups were comparable for volume of ORS solution consumed, time taken for initial rehydration, mean stool output and for correcting biochemical abnormalities.

Time dependent effects of hormones on rate of protein synthesis in lymphoid organs of chickens

Total protein content in blood serum and different lymphoid organs, such as bursa, spleen and thymus was investigated in chickens at two different circadian stages (0800 or 1600 hrs; early or late photophase) following administration of either saline or hormones (thyroxine or hydrocortisone or epinephrine). The results suggest that the lymphoid organs may respond differently to the exogenous administration of different hormones depending on the time of their administration.