Tissue Heart Valve Replacement at BSMMU- Initial Experience with Two Cases

Research on prosthesis to replace diseased heart valves began almost simultaneously with mechanical valves which aredurable but with inherent thromboembolic complication requiring life-long anticoagulant therapy and tissue valves whichare more prone to structural failure but free from thromboembolic complication. Tissue valves are more useful in females ofreproductive age desiring a child, male patients older than 60 years of age and female patients over 55 years of age, patientshaving chronic liver disease, history of stroke, bleeding disorder and in presence of infective endocarditis. Gluteraldehydefixation at low pressure with removal of maximal amount of phospholipid have increased the durability of tissue valves inrecent years. Considering the better quality of life with tissue valve the trend is shifting towards using it more frequentlyaround the world. Recently two heart valve replacement operations using bovine perimount pericardial valve were done inthe department of cardiac surgery, BSMMU, one in aortic position another in mitral position, both in females of reproductiveage desiring children.The operations were technically demanding but the outcomes were uneventful. Tissue heart valvereplacement is a safe procedure and can be useful in female of child bearing age desiring children.Key Words: Tissue heart valve replacement; Aortic valve; Mitral valve; Bioprosthetic heart valves; Bovine perimountpericardial valve.DOI: 10.3329/bsmmuj.v3i1.5511BSMMU J 2010; 3(1): 27-3

Weighted and unweighted network of amino acids within protein

The information regarding the structure of a single protein is encoded in the network of interacting amino acids. Considering each protein as a weighted and unweighted network of amino acids we have analyzed a total of forty nine protein structures that covers the three branches of life on earth. Our results show that the probability degree distribution of network connectivity follows Poisson's distribution; whereas the probability strength distribution does not follow any known distribution. However, the average strength of amino acid node depends on its degree (k). For some of the proteins, the strength of a node increases linearly with k. On the other hand, for a set of other proteins, although the strength increases linaerly with k for smaller values of k, we have not obtained any clear functional relationship of strength with degree at higher values of k. The results also show that the weight of the amino acid nodes belonging to the highly connected nodes tend to have a higher value. The result that the average clustering coefficient of weighted network is less than that of unweighted network implies that the topological clustering is generated by edges with low weights. The ratio of average clustering coefficients of protein network to that of the corresponding classical random network varies linearly with the number (N) of amino acids of a protein; whereas the ratio of characteristic path lengths varies logarithmically with N. The power law behaviour of clustering coefficients of weighted and unweighted network as a function of degree k indicates that the network has a signature of hierarchical network. It has also been observed that the network is of assortative type

Late presentation of congenital diaphragmatic hernia: A diagnostic dilemma

Congenital diaphragmatic hernias are commonly symptomatic within 24 hours after birth, but late presentation is not uncommon. Late presentation of congenital diaphragmatic hernia poses diagnostic difficulties as clinical picture are vague, and more commonly presented with non-specific gastrointestinal and respiratory symptoms. Due to the vague and non-specific clinical presentation, clinician faces a diagnostic dilemma resulting in delay in diagnosis and many a times an inappropriate management. This article reports 2 cases of late-presenting congenital diaphragmatic hernia (over the period of 6 months from September 2014 to February 2015) in National Institute of Disease of Chest and Hospital (NIDCH). In first case, she was diagnosed as right-sided tubercular pleural effusion and was treated with CAT-1 anti-tubercular therapy for 6 months without any clinical improvement. Later CT scan of chest was done and diagnosed as a case of congenital diaphragmatic hernia. The second case was diagnosed as a left-sided hydropneumothorax and treated with left tube thoracostomy. During removal of the intercostal chest tube, some fatty tissue was pulled out of the thoracostomy site. In NIDCH, she was diagnosed as a case of diaphragmatic hernia by barium follow-through. Both cases were diagnosed as Bochdalek hernia during the repair of the hernia defect via thoracotomy

Growth, Fatty Acid, and Lipid Composition of Marine Microalgae Skeletonema costatum

Among the various potential sources of renewable energy, biofuels are of most interest. Marine microalgae are the most promising oil sources for making biofuels, which can grow very rapidly and convert solar energy to chemical energy via CO2 fixation. The fatty acid profile of almost all the microalgal oil is suitable for the synthesis of biofuel. In this research, fatty acid and lipid contents of Bangladeshi strains of marine microalgae Skeletonema costatum were performed. For this, the crude oil was extracted by Soxhlet extraction method, using three most common solvent systems, pure hexane and mixture of CHCl3 : MeOH (2 : 1) and hexane : EtOH (3 : 1) one by one. Highest oil recovery (15.37%) came from CHCl3 : MeOH (2 : 1) solvent system from dry biomass whereas the lowest (2.49%) came from n-hexane from wet biomass. The qualitative analysis of the extracted oil by GC/MS analysis revealed that it contained significant amount of myristic acid (C14:0), palmitic acid (C16:0), stearic acid (C18:0), and palmitoleic acid (C16:1). It also indicated presence of hexadecatrienoic acid, benzenedicarboxylic acid, oleic acid, arachidonic acid, eicosapentaenoic acid (EPA), 9-Octadecenoic acid methyl ester (C19H36O2), and so forth. The obtained fatty acid profile indicates high potentiality of S. costatum species to be used as promising biofuel feedstock a little improvisation and substantially it can replace diesel in near future

Hydrophobic, hydrophilic and charged amino acids' networks within Protein

The native three dimensional structure of a single protein is determined by the physico chemical nature of its constituent amino acids. The twenty different types of amino acids, depending on their physico chemical properties, can be grouped into three major classes - hydrophobic, hydrophilic and charged. We have studied the anatomy of the weighted and unweighted networks of hydrophobic, hydrophilic and charged residues separately for a large number of proteins. Our results show that the average degree of the hydrophobic networks has significantly larger value than that of hydrophilic and charged networks. The average degree of the hydrophilic networks is slightly higher than that of charged networks. The average strength of the nodes of hydrophobic networks is nearly equal to that of the charged network; whereas that of hydrophilic networks has smaller value than that of hydrophobic and charged networks. The average strength for each of the three types of networks varies with its degree. The average strength of a node in charged networks increases more sharply than that of the hydrophobic and hydrophilic networks. Each of the three types of networks exhibits the 'small-world' property. Our results further indicate that the all amino acids' networks and hydrophobic networks are of assortative type. While maximum of the hydrophilic and charged networks are of assortative type, few others have the characteristics of disassortative mixing of the nodes. We have further observed that all amino acids' networks and hydrophobic networks bear the signature of hierarchy; whereas the hydrophilic and charged networks do not have any hierarchical signature.Comment: Corresponding author: Sudip Kund

Effect of green tea on serum cholesterol level in cholesterol fed rabbits

Background: Since the development of atherosclerosis involves dyslipidemia, we postulated that green tea may exert lowering of serum cholesterol levels. Objectives: To investigate the effects of green tea on serum cholesterol level. Methods: Total 45 rabbits (15 were fed on 1% cholesterol and green tea for 16 weeks, another 15 were fed on 1% cholesterol and plain water for 16 weeks, last batch of 15 rabbits received normal rabbit diet for 16 weeks) in the department of Cardiac Surgery, Bangabandhu Sheikh Mujib Medical University, Dhaka from April 2011 to September 2012.They were evaluated for lipid profile and presence of atherosclerosis. Results: The mean total cholesterol in cholesterol fed rabbits with green tea after 16 weeks was 21.06 ± 5.55, LDL-C was 20.80 ± 6.16, Serum TG was 153.67 ± 33.59, HDL-C neither increased nor decreased. The mean total cholesterol in cholesterol fed rabbits with plain water after 16 weeks was 27 .53 ± 5.15, LDL-C was 32.40 ± 8.24 and TG was 290.13 ± 44.31, no effect were seen on HDL-C. These rabbits were fed on green tea for 8 weeks, cholesterol levels returned to levels at commencement of experiment. Rabbits fed on normal rabbit diet for 16 weeks had TC l9.20 ± 4.85, LDL-C was 19.20 ± 2.04 and TG was 155.06 ± 32.03 mg/dl. HDL-C remained in normal range. But there was no atheroschlerotic change in any group. Conclusion: Green tea significantly reduces serum cholesterol levels in cholesterol fed rabbits. There was no effect of green tea on HDL-C in any group

Static and dynamic characteristics of protein contact networks

The principles underlying protein folding remains one of Nature's puzzles with important practical consequences for Life. An approach that has gathered momentum since the late 1990's, looks at protein hetero-polymers and their folding process through the lens of complex network analysis. Consequently, there is now a body of empirical studies describing topological characteristics of protein macro-molecules through their contact networks and linking these topological characteristics to protein folding. The present paper is primarily a review of this rich area. But it delves deeper into certain aspects by emphasizing short-range and long-range links, and suggests unconventional places where "power-laws" may be lurking within protein contact networks. Further, it considers the dynamical view of protein contact networks. This closer scrutiny of protein contact networks raises new questions for further research, and identifies new regularities which may be useful to parameterize a network approach to protein folding. Preliminary experiments with such a model confirm that the regularities we identified cannot be easily reproduced through random effects. Indeed, the grand challenge of protein folding is to elucidate the process(es) which not only generates the specific and diverse linkage patterns of protein contact networks, but also reproduces the dynamic behavior of proteins as they fold. Keywords: network analysis, protein contact networks, protein foldingComment: Added Appendix

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Perspectives on climate change and inland fisheries in India

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