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M Ullah

Publications and source records attributed to M Ullah.

11 recordsLinked to original sources
PubMed2006

Deterministic modelling and stochastic simulation of biochemical pathways using MATLAB.

The analysis of complex biochemical networks is conducted in two popular conceptual frameworks for modelling. The deterministic approach requires the solution of ordinary differential equations (ODEs, reaction rate equations) with concentrations as continuous state variables. The stochastic approach involves the simulation of differential-difference equations (chemical master equations, CMEs) with probabilities as variables. This is to generate counts of molecules for chemical species as realisations of random variables drawn from the probability distribution described by the CMEs. Although there are numerous tools available, many of them free, the modelling and simulation environment MATLAB is widely used in the physical and engineering sciences. We describe a collection of MATLAB functions to construct and solve ODEs for deterministic simulation and to implement realisations of CMEs for stochastic simulation using advanced MATLAB coding (Release 14). The program was successfully applied to pathway models from the literature for both cases. The results were compared to implementations using alternative tools for dynamic modelling and simulation of biochemical networks. The aim is to provide a concise set of MATLAB functions that encourage the experimentation with systems biology models. All the script files are available from www.sbi.uni-rostock.de/ publications_matlab-paper.html.

Biochemistry↗
PubMed2005

A systems- and signal-oriented approach to intracellular dynamics.

A mathematical understanding of regulation, and, in particular, the role of feedback, has been central to the advance of the physical sciences and technology. In this article, the framework provided by systems biology is used to argue that the same can be true for molecular biology. In particular, and using basic modular methods of mathematical modelling which are standard in control theory, a set of dynamic models is developed for some illustrative cell signalling processes. These models, supported by recent experimental evidence, are used to argue that a control theoretical approach to the mechanisms of feedback in intracellular signalling is central to furthering our understanding of molecular communication. As a specific example, a MAPK (mitogen-activated protein kinase) signalling pathway is used to show how potential feedback mechanisms in the signalling process can be investigated in a simulated environment. Such 'what if' modelling/simulation studies have been an integral part of physical science research for many years. Using tools of control systems analysis, as embodied in the disciplines of systems biology, similar predictive modelling/simulation studies are now bearing fruit in cell signalling research.

Cells↗
PubMed1998

Effect of pH on physiology of Metarhizium anisopliae for production of swainsonine.

The effect of pH on the production of swainsonine and fungal morphology at different stages of fermentation of Metarhizium anisopliae was investigated. When no control was applied, the pH of the culture dropped from 6.5 to 3.8 within the first 72 hours and the concentration of swainsonine reached 43.3 mg 1(-1). When the pH was held constant either at the beginning or throughout the fermentation, the maximum recorded swainsonine level was only 8.4 mg 1(-1) corresponding with an increase in the formation of pellets. A late pH control applied after 72 hours, resulted in a swainsonine titer of 45.5 mg 1(-1).

Antineoplastic Agents, Phytogenic↗
PubMed1990

Gentamicin induced dose related alterations in lipid levels and lipid peroxidation in central auditory pathway of the rat.

A study was carried out on the effect of gentamicin on the central auditory pathway in rats. Rats were administered graded doses of gentamicin (60 mg, 100 mg and 160 mg/kg b.wt., i.m.) daily for 21 days. Levels of total lipids, phospholipids and cholesterol showed dose related increment in the central auditory pathway. On the other hand, the rate of lipid peroxidation was inhibited in all regions of the central auditory pathway of the rat.

Animals↗
PubMed1986

Localisation of the spinal nucleus of the accessory nerve in the rabbit.

The spinal nucleus of the accessory nerve (SNA) was localised in eight adult rabbits by a retrograde degeneration technique using thionine as a stain for the Nissl substance. The SNA was found to extend from the caudal one fifth of the medulla oblongata to the cranial one fourth of the sixth cervical segment. In the caudal part of the medulla oblongata, the SNA was located in the dorsal part of the detached ventral grey column. In the first cervical segment, the SNA was dorsolateral to the dorsomedial column and dorsal to the ventromedial column of the ventral grey column. In the cranial part of the second cervical segment, the SNA shifted laterally to the lateral margin of the ventral grey column. After this lateral shift, the SNA was located in the lateral part of the ventral grey column of the second, third and fourth cervical segments. In the fifth and cranial one fourth of the sixth cervical segments, the SNA was not a well defined column of cells but was represented by isolated cells scattered in the ventral part of the ventral grey column between the phrenic nucleus and the ventral border of the grey matter. The total number of chromatolysed cells found in the SNA of the right experimental side varied from 2723 to 3210.

Accessory Nerve↗
PubMed1985

The attachments of the lateral and medial ends of the extensor retinaculum of the human wrist.

The attachments of the lateral and medial ends of the extensor retinaculum of the human wrist were observed in 52 human upper limbs (from 26 cadavers) by dissection. In all the specimens used in this study, the lateral end of the retinaculum was found to be attached to the distal part of the anterior border of the radius and its medial end was attached to the styloid process of the ulna, the pisiform and the triquetrum.

Humans↗
PubMed1978

Localization of the phrenic nucleus in the spinal cord of the rabbit.

The motor fibres of the phrenic nerve arise in the cervical portion of the spinal cord from a group of lower motor neuron cell bodies called the 'phrenic nucleus'. The phrenic nucleus of the rabbit has been located by cutting the right phrenic nerve (phrenicotomy) in the neck and observing retrograde degeneration (chromatolysis) in the cells of the ventral grey horn of the spinal cord 2-4 weeks later. The phrenic nucleus in the rabbit was found to extend from the fourth to the sixth cervical segment. It lay in the caudal half to three fourths of the fourth, the whole of the fifth and the cranial half to two thirds of the sixth segment. The phrenic nucleus in the rabbit is a longitudinal column of cells lying between the ventromedial and the ventrolateral columns of the ventral grey horn of the spinal cord. In the fourth and fifth cervical segments, the phrenic nucleus of the rabbit is dorso-medial to the ventrolateral column and dorsolateral to the ventromedial column. In the sixth segment it is dorsomedial to the ventrolateral column but lateral to the ventromedial column. The total number of chromatolysed cells found in the right phrenic nucleus (after right phrenicotomy in the neck) varied between 1496 and 1754. The chromatolysed cells had a peculiar and characteristic orientation in that in a frontal section they appeared longer than broad with their long axes almost parallel ti the longitudinal axis of the spinal cord.

Animals↗
PubMedDate not supplied

The obstetric performance of United Kingdom asylum seekers from Somalia: a case-control study and literature review.

BACKGROUND: Little published research exists regarding obstetric performance of immigrant women in the United Kingdom. The aim of this study was to evaluate the obstetric performance and fetal outcomes of Somalian women who received prenatal care and requested to deliver at a teaching hospital in North London. METHOD: This is a case-control study in which consecutive Somalian women were identified as index cases and the subsequent British-born Caucasian women listed in the delivery book served as controls. RESULTS: 69 index and 69 control cases were analyzed. Fifty-five percent of the Somalian women spoke little or no English. Half (50%) had undergone circumcision, the majority being type I WHO classification of female genital circumcision, which did not require significant surgical intervention prior to labor; 13% had cesarean sections, 13% instrumental vaginal deliveries, and 74% had vaginal deliveries. The Somalian women had higher parity (2.35 vs. 1.18) and were more likely to be grand multiparous (9/69 vs. 1/69) compared to controls. Epidural use was less frequent in Somalian women, but otherwise there were no significant differences between the two groups with regard to maternal age, rates of induction of labor, cesarean sections, duration of labor, premature deliveries, instrumental deliveries, and birth weights. CONCLUSIONS: The demographic characteristics of the Somalian female population appear to exert minimal effect on obstetric and fetal outcomes. This may be due to the increased vigilance exercised by health professionals as well as to the fact that recent arrivals are from more urban and westernized areas in Somalia.

Adult↗