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771.
Kaushik Kumar Majumdar 《Cognitive neurodynamics》2007,1(4):295-303
Brain is an expert in producing the same output from a particular set of inputs, even from a very noisy environment. In this
article a model of neural circuit in the brain has been proposed which is composed of cyclic sub-circuits. A big loop has
been defined to be consisting of a feed forward path from the sensory neurons to the highest processing area of the brain
and feed back paths from that region back up to close to the same sensory neurons. It has been mathematically shown how some
smaller cycles can amplify signal. A big loop processes information by contrast and amplify principle. How a pair of presynaptic
and postsynaptic neurons can be identified by an exact synchronization detection method has also been mentioned. It has been
assumed that the spike train coming out of a firing neuron encodes all the information produced by it as output. It is possible
to extract this information over a period of time by Fourier transforms. The Fourier coefficients arranged in a vector form
will uniquely represent the neural spike train over a period of time. The information emanating out of all the neurons in
a given neural circuit over a period of time can be represented by a collection of points in a multidimensional vector space.
This cluster of points represents the functional or behavioral form of the neural circuit. It has been proposed that a particular
cluster of vectors as the representation of a new behavior is chosen by the brain interactively with respect to the memory
stored in that circuit and the amount of emotion involved. It has been proposed that in this situation a Coulomb force like
expression governs the dynamics of functioning of the circuit and stability of the system is reached at the minimum of all
the minima of a potential function derived from the force like expression. The calculations have been done with respect to
a pseudometric defined in a multidimensional vector space. 相似文献
772.
Kakali arkar Himadri Sekhar Sarkar Labanyamoy Kole Pijush K. Das 《Molecular and cellular biochemistry》1996,156(2):109-116
The characteristics of the recognition system involved in the receptor mediated endocytosis of the neoglycoprotein, fucose human serum albumin (HSA) were studied. It was found that (i) fucose-HSA showed strong affinity binding and uptake by various macrophages; (ii) binding was specific for L-fucose and D-mannose; (iii) binding was found to be inhibited by oxidant like H2O2 and swainsonine whereas it was elevated by dexamethasone; (iv) clearance of125I-fucose-HSA was rapid and strongly inhibited by unlabelled fucose-HSA. Greater than 70% of fucose-HSA was found in liver and more than 60% of this was found in liver lysosomes; (v) uptake of fucose-HSA was thirty-fold more efficient in liver macrophages (Kupffer cells) than in hepatocytes; (vi) moreover, mannose-HSA and ovalbumin which are potent inhibitors of mannose/N-acetylglucosamine receptors inhibited clearance and uptake of fucose-HSA by liver as well as by isolated Kupffer cells suggesting the involvement of both fucose and mannose receptors or a single type of receptor having greater affinity for fucose-HSA than for mannose-HSA. These results emphasize the important role of fucose-terminated glycoproteins in site-specific drug targeting. 相似文献
773.
Shyamal K. Majumdar 《Planta》1970,90(2):212-214
Summary In a modified culture medium, excised ovaries of Haworthia turgida var. pallidifolia can be grown to the normal looking capsules; the ovary wall can produce leafy shoots and callus tissue in this medium. The callus tissue in turn is found to differentiate into plantlets. 相似文献
774.
775.
ABSTRACT COVID-19 is a highly contagious disease caused by Severe Acute Respiratory Syndrome coronavirus-2, capable of high human transmission. To protect against the COVID-19 pandemic, the World Health Organization proposed intervening guidance that included movement restrictions, isolation, restriction of national and international travel or movement, and full or partial closure of organizations and institutions. Police personnel play a vital role in safeguarding the spread of COVID-19; thus, potentially causing severe stress due to increased consignment and direct exposure to infection during duty. The study aimed to determine the effect of the added stress of the COVID-19 pandemic and population lockdown on the sleep/wake 24 h rhythm of traffic police. A concise online questionnaire survey was conducted among the traffic police personnel of India. Collected data were analyzed statistically. Disorientation of working schedule, fear of being vulnerable to disease, pressure of maintaining law, and orders during lockdown increased stress level. The survey identified discontinuation of sleep, shift of mid-sleep time, increase in depression, plus stress and anxiety among traffic police personnel that affected their chronobiological milieu. Proper awareness of adequate health and safety measures, use of personnel protection equipment, regular conversation with family members, and meditation can help reduce stress during this pandemic situation. 相似文献
776.
The effects of gastrin, epidermal growth factor, and somatostatin on DNA synthesis in a small intestinal crypt cell line (IEC-6) 总被引:6,自引:0,他引:6
C N Conteas A P Majumdar 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1987,184(3):307-311
Exposure of IEC-6 cells for 24 hr to either gastrin (50-500 ng/ml) or EGF (100-500 ng/ml) significantly stimulated (100-165%) the rate of [3H]thymidine incorporation into DNA (referred to as DNA synthesis) when compared with the corresponding basal levels. Somatostatin (10-500 ng/ml) produced no apparent change in DNA synthesis in IEC cells. On the other hand, somatostatin completely inhibited the EGF-induced rise in DNA synthesis. The gastrin-mediated stimulation in DNA synthesis was not affected by somatostatin. The rate of DNA synthesis in IEC cells in the presence of both gastrin and EGF was found to be greater (additive) than that caused by either of the peptides alone. A similar but less dramatic change in the actual number of cells (assessment of cell replication) was observed when the IEC cells were exposed for 24 hr to gastrin, EGF, and somatostatin, either alone or in combination. Whereas gastrin (250 ng/ml) and EGF (250 ng/ml) by themselves increased the number of cells significantly by 29 and 37%, respectively, together they caused a 72% stimulation, when compared with the basal levels. Somatostatin by itself caused no apparent change in IEC cell population, but it significantly inhibited the EGF- but not the gastrin-induced stimulation in IEC cell replication. It is concluded that both gastrin and EGF exert a direct proliferative effect on IEC cells, and the EGF action is regulated by somatostatin. 相似文献
777.
Ramnath Sharma K. K. De Bibaychana Sharma Sudipta Majumdar 《Journal of Plant Biology》2005,48(2):253-257
Present studies have demonstrated that immature seeds obtained from green pod ofDendrobium fimbriatum Hook., an endangered epiphytic forest orchid having horticultural importance, can be germinated asymbioticallyin vitro for rapid micropropagation. Vacin and Went medium containing 0.1 mg L-1 NAA and 15% coconut water was found most effective for high percentage (80-90%) seed germination and seedling development.
This method can be exploited for their rapid micropropagation and conservation. 相似文献
778.
779.
Arunabha Majumdar Claudia Giambartolomei Na Cai Tanushree Haldar Tommer Schwarz Michael Gandal Jonathan Flint Bogdan Pasaniuc 《PLoS computational biology》2021,17(5)
Genetic predisposition for complex traits often acts through multiple tissues at different time points during development. As a simple example, the genetic predisposition for obesity could be manifested either through inherited variants that control metabolism through regulation of genes expressed in the brain, or that control fat storage through dysregulation of genes expressed in adipose tissue, or both. Here we describe a statistical approach that leverages tissue-specific expression quantitative trait loci (eQTLs) corresponding to tissue-specific genes to prioritize a relevant tissue underlying the genetic predisposition of a given individual for a complex trait. Unlike existing approaches that prioritize relevant tissues for the trait in the population, our approach probabilistically quantifies the tissue-wise genetic contribution to the trait for a given individual. We hypothesize that for a subgroup of individuals the genetic contribution to the trait can be mediated primarily through a specific tissue. Through simulations using the UK Biobank, we show that our approach can predict the relevant tissue accurately and can cluster individuals according to their tissue-specific genetic architecture. We analyze body mass index (BMI) and waist to hip ratio adjusted for BMI (WHRadjBMI) in the UK Biobank to identify subgroups of individuals whose genetic predisposition act primarily through brain versus adipose tissue, and adipose versus muscle tissue, respectively. Notably, we find that these individuals have specific phenotypic features beyond BMI and WHRadjBMI that distinguish them from random individuals in the data, suggesting biological effects of tissue-specific genetic contribution for these traits. 相似文献
780.