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Showing posts from March, 2015

Why Biological Systems Suddenly Change State: An Intuitive Guide to Freidlin–Wentzell Theory

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  Stochasticity is ubiquitous in biology and neuroscience, manifesting in various forms, including ion channel noise, synaptic variability, gene regulatory fluctuations, noisy population dynamics, and more. Many biological systems spend long periods in a stable “state” and only rarely transition to another state due to noise. For instance, a neuron typically remains inactive but may occasionally trigger a spontaneous spike. Similarly, a gene can switch from the OFF state to the ON state due to rare bursts of transcription factors. Cells can also transition out of metabolic or epigenetic states, populations might shift between different ecological equilibria, and a viral infection can fluctuate between phases of control and uncontrollability. Freidlin–Wentzell theory provides a mathematically rigorous framework to study these phenomena when noise is small but nonzero . It tells you, firstly, h ow likely rare transitions are,    secondly,   h ow fast they occ...
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Percutaneous Injection of Radiopaque Gelified Ethanol for the Treatment of Lumbar and Cervical Intervertebral Disk Herniations

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Experience and Clinical Outcome in 80 Patients link to the article BACKGROUND AND PURPOSE:  Chemonucleolysis represents a minimally invasive percutaneous technique characterized by an intradiskal injection of materials under fluoroscopic or CT guidance. Recently, a substance based on radiopaque gelified ethanol has been introduced. The purpose of this study was to describe the indications, procedure, safety, and efficacy of radiopaque gelified ethanol in the percutaneous treatment of cervical and lumbar disk herniations. MATERIALS AND METHODS:  Between September 2010 and August 2013, 80 patients (32 women and 48 men; age range, 18–75 years) were treated for 107 lumbar disk herniations (L2–L3,  n  = 1; L3–L4,  n  = 15; L4–L5,  n  = 53; and L5–S1,  n  = 38) and 9 cervical disk herniations (C4–C5,  n  = 2; C5–C6,  n  = 2; C6–C7,  n  = 3; and C7–D1,  n  = 2) by percutaneous intradiskal i...
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Cerebral Circulation Time is Prolonged and Not Correlated with EDSS in Multiple Sclerosis Patients

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Literature has suggested that changes in brain flow circulation occur in patients with multiple sclerosis .  In this study , digital subtraction angiography (DSA) was used to measure the absolute CCT value in MS patients and to correlate its value to age at disease onset and duration, and to expand disability status scale (EDSS).  DSA assessment was performed on eighty MS patients and on a control group of forty-four age-matched patients. CCT in MS and control groups was calculated by analyzing the angiographic images. Lesion and brain volumes were calculated in a representative group of MS patients. Statistical correlations among CCT and disease duration, age at disease onset, lesion load, brain volumes and EDSS were considered.  A significant difference between CCT in MS patients (mean = 4.9s; sd = 1.27s) and control group (mean = 2.8s; sd = 0.51s) was demonstrated. No significant statistical correlation was found between CCT and the other parameters in all MS pat...
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Next generation sequencing in sporadic retinoblastoma patients reveals somatic mosaicism

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In about 50 %  of sporadic cases of retinoblastoma, no constitutive RB1 mutations are detected by conventional methods.  However, recent research suggests that, at least in some of these cases, there is somatic mosaicism with respect to RB1 normal and mutant alleles. The increased availability of next generation sequencing improves our ability to detect the exact percentage of patients with mosaicism. Using this technology, we re-tested a series of 40 patients with sporadic retinoblastoma: 10 of them had been previously classified as constitutional heterozygotes, whereas in 30 no RB1 mutations had been found in lymphocytes. In 3 of these 30 patients, we have now identified low-level mosaic variants, varying in frequency between 8 and 24 % . In 7 out of the 10 cases previously classified as heterozygous from testing blood cells, we were able to test additional tissues (ocular tissues, urine and / or oral mucosa): in three of them, next generation sequencing has revealed mosai...
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Lifelong accumulation of amyloid in neurons may contribute to Alzheimer's Disease

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A research team at the Cognitive Neurology and Alzheimer’s Disease Center   - Northwestern University, Illinois, USA, found that the protein amyloid - a hallmark of this disease - begins to accumulate in the neurons of the brain since the age of 20 [ see more here  ] . Scientists believe that this is the first time that such changes were observed in the human brain of individuals so young. Prof. Changiz Gheula said: Discovering that amyloid begins to accumulate so early in life is unprecedented.  This is very significant.  We know that amyloid, when present for long periods of time, is bad for you. For the study, brains of deceased people in the age range from 20 to 95 were considered. Specifically, the sample included  twenty-one people with Alzheimer's disease aged between 60 and 95,  sixteen people aged between 70 and 79 without dementia, and thirteen  "normal" people aged between 20 and 66 years.     The findings are publishe...
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Understanding Anaerobic Threshold (VT2) and VO2 Max in Endurance Training

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  Introduction: The Science Behind Ventilatory Thresholds VT1 vs. VT2: Defining Energy Transitions p (Aerobic Threshold) : The transition from lipid metawwwpp (fat-burning) to a mixed metabolism, where both carbohydrates and fats fuel muscle activity. V0T2 (Anaerobic Threshold) : The point where the  shifts to a predominantly carbohydrate-based wmetabolism , leading to rapid lactate waccumpulation and increased reliance on anaerobic energy pathways. www w In p VT1 and VT2 Wwww ewAgep & Sex Younger athletes generally exhibit higher VT2 values , while aging naturally reduces aerobicw capacity. Men tend to have a higher VO2 Max due to greater lung capacity and muscle mass, but women can achieve similar endurance levels through optimized training. Body Composition & Health Status High body fat percentage may reduce VT2 efficiency, as excess weight increases ...
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Owen's Function: A Simple Solution to Complex Problems

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Definition   If you are interested in statistics or probability, you may have encountered the Owen's function , a special function that arises in various applications involving bivariate normal distributions. Let’s explain what Owen's function is, how it is defined and notated, and why it is useful.  The Owen's function is defined as follows: for any real numbers h and a, Owen's function T(h,a) is given by T ( h , a ) = 1 2 π · ∫ 0 a exp ( - h 2 2 · ( 1 ...
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Cell Count Analysis with cycleTrendR

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  1. Introduction Long‑term monitoring of adherent cell cultures (e.g., Vero, MDCK) is central to vaccine development, viral propagation, and QC workflows in CRO environments. Standard analyses typically focus on short‑term growth metrics such as doubling time, confluence progression, and endpoint viability. While informative, these metrics overlook slow drifts, cyclic environmental influences, and structural transitions that emerge over multi‑day or multi‑week monitoring. Operational routines (e.g., weekly medium changes), environmental oscillations (e.g., daily temperature cycles), and metabolic rhythms can introduce periodic components into cell‑density trajectories. These patterns are rarely analyzed explicitly, despite their potential impact on viral yield, infection kinetics, and batch‑to‑batch reproducibility. This post demonstrates how cycleTrendR can extract long‑term trends, dominant cycles, and structural transitions from a realistically simulated adherent cell‑co...
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