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Biomedical subjects

P K Biswas

Publications and source records attributed to P K Biswas.

At least 19 recordsLinked to original sources
PubMed2006

Causes of loss of Sonali chickens on smallholder households in Bangladesh.

In a 1-year-long prospective longitudinal study, we determined the causes of loss of 'Sonali' (male symbol Rhode Island Red x female symbol Fayoumi) chickens at key-rearers' households of the smallholder livestock development project-2 (SLDP-2) area in Bangladesh. A key rearer is a smallholder of chickens in the 'village poultry-production chain' (undertaken by SLDP-2 under the financial assistance of the DANIDA) who rears at least five Sonali and some 'Deshi' (non-descriptive and indigenous) chickens in their homesteads based on semi-scavenging system. The aim of this program is to ameliorate poverty, especially among women. Two co-ordination centers (set at the Potuakhali and Noakhali districts) supervised the development activities. We selected two upazilas (lower administration units) randomly from each of the two districts and in every selected upazila, we selected at random 125 key-rearer households. Incidence rates of loss of Sonali chickens from disease, predation, selling and slaughtering were 0.025, 0.023, 0.081 and 0.039 per bird-month at risk, respectively. The major predators of Sonali chickens in the study area were foxes, a kind of wild cat (Felis chaus), mongooses and human thieves. Colibacillosis (both single and mixed infections) had a contributory role in the death of 28% of dead Sonali birds collected for diagnosis; salmonellosis, Newcastle disease and internal parasites contributed to the next highest (14, 11and 10%) proportional mortalities.

Animal Husbandry↗
PubMed2006

Rotation-invariant texture image retrieval using rotated complex wavelet filters.

This paper proposes a novel approach for rotation-invariant texture image retrieval by using set of dual-tree rotated complex wavelet filter (DT-RCWF) and DT complex wavelet transform (DT-CWT) jointly, which obtains texture features in 12 different directions. Two-dimensional RCWFs are nonseparable and oriented, which improves characterization of oriented textures. Robust and efficient isotropic rotationally invariant features are extracted from DT-RCWF and DT-CWT decomposed subbands. This paper demonstrates the effectiveness of this new set of features on four different sets of rotated and nonrotated databases. Experimental results indicate that the proposed method improves retrieval accuracy from 83.17% to 93.71% on a small size (208 images) nonrotated database D1, from 82.71% to 90.86% on a small size (208 images) rotated database D2, from 72.18% to 76.09% on a medium-size (640 images) rotated database D3, and from 64.17% to 78.93% on a large size (1856 images) rotated database D4, compared with the discrete wavelet transform-based approach. New method also retains comparable levels of computational complexity.

Journal Article↗
PubMed2005

A regularized and renormalized electrostatic coupling Hamiltonian for hybrid quantum-mechanical-molecular-mechanical calculations.

We describe a regularized and renormalized electrostatic coupling Hamiltonian for hybrid quantum-mechanical (QM)-molecular-mechanical (MM) calculations. To remedy the nonphysical QM/MM Coulomb interaction at short distances arising from a point electrostatic potential (ESP) charge of the MM atom and also to accommodate the effect of polarized MM atom in the coupling Hamiltonian, we propose a partial-wave expansion of the ESP charge and describe the effect of a s-wave expansion, extended over the covalent radius r(c), of the MM atom. The resulting potential describes that, at short distances, large scale cancellation of Coulomb interaction arises intrinsically from the localized expansion of the MM point charge and the potential self-consistently reduces to 1r(c) at zero distance providing a renormalization to the Coulomb energy near interatomic separations. Employing this renormalized Hamiltonian, we developed an interface between the Car-Parrinello molecular-dynamics program and the classical molecular-dynamics simulation program Groningen machine for chemical simulations. With this hybrid code we performed QM/MM calculations on water dimer, imidazole carbon monoxide (CO) complex, and imidazole-heme-CO complex with CO interacting with another imidazole. The QM/MM results are in excellent agreement with experimental data for the geometry of these complexes and other computational data found in literature.

Carbon Monoxide↗
PubMed2005

A longitudinal study of the incidence of major endemic and epidemic diseases affecting semi-scavenging chickens reared under the Participatory Livestock Development Project areas in Bangladesh.

A 17-month (from January 2002 to May 2003) longitudinal study was undertaken to elucidate the epidemiology of important endemic and epidemic diseases affecting semi-scavenging chickens reared in the Participatory Livestock Development Project area in Bangladesh. This project was implemented in 17 northern and north-central districts of Bangladesh, under which 361 839 rural poor people were assisted to undertake poultry-rearing activity as a tool of poverty reduction. Of the total beneficiaries 93% were "key rearers". A key rearer is defined as a beneficiary who generally rears 10 to 13 hens in a semi-scavenging system with little additional feed supply. Households of 650 key rearers and some chick rearers were observed. During the study period 1227 birds, which belonged to different age, breed and sex categories, were found dead as a result of disease occurrence. From every dead bird organ samples such as the liver, heart, spleen, brain lung, trachea and bursa of Fabricius were collected. The incidence rate of mortality was 0.01976 per bird-months at risk. Of the total deaths 58.44% had single or mixed type of infections. Newcastle disease had the highest proportional mortality rate (15.81%). The proportional mortality caused by fowlpox, fowl cholera, salmonellosis, colibacillosis, aspergillosis, infectious bursal disease, mixed infections and undiagnosed cases were 8.96%, 6.76%, 7.09%, 6.93%, 0.33%, 2.04%, 10.51% and 41.56%, respectively. Newcastle disease affected a significant higher proportion (18.81%) of birds older than 60 days of age (P=0.00). Younger birds (age < or = 60 days) had a higher proportional mortality due to fowlpox and infectious bursal disease than older birds (P=0.00). Sonali (male Rhode Island Red x female Fayoumi) birds reared under the semi-scavenging system had a higher infection rate with Newcastle disease virus compared with indigenous and Fayoumi birds (P=0.00). Fowlpox was more prevalent in Fayoumi birds compared with Sonali. Surprisingly, Newcastle disease was more common in the vaccinated birds rather than the unvaccinated birds.

Age Factors↗
PubMed2005

Texture image retrieval using new rotated complex wavelet filters.

A new set of two-dimensional (2-D) rotated complex wavelet filters (RCWFs) are designed with complex wavelet filter coefficients, which gives texture information strongly oriented in six different directions (45 degrees apart from complex wavelet transform). The 2-D RCWFs are nonseparable and oriented, which improves characterization of oriented textures. Most texture image retrieval systems are still incapable of providing retrieval result with high retrieval accuracy and less computational complexity. To address this problem, we propose a novel approach for texture image retrieval by using a set of dual-tree rotated complex wavelet filter (DT-RCWF) and dual-tree-complex wavelet transform (DT-CWT) jointly, which obtains texture features in 12 different directions. The information provided by DT-RCWF complements the information generated by DT-CWT. Features are obtained by computing the energy and standard deviation on each subband of the decomposed image. To check the retrieval performance, texture database D1 of 1856 textures from Brodatz album and database D2 of 640 texture images from VisTex image database is created. Experimental results indicates that the proposed method improves retrieval rate from 69.61% to 77.75% on database D1, and from 64.83% to 82.81% on database D2, in comparing with traditional discrete wavelet transform based approach. The proposed method also retains comparable levels of computational complexity.

Algorithms↗
PubMed2000

Hepatopulmonary syndrome in inferior vena cava obstruction responding to cavoplasty.

Reports show that hepatopulmonary syndrome mostly occurs in the setting of advanced hepatic dysfunction, with the associated vasoactive substance imbalance believed to be responsible for its pathogenesis. However, hepatopulmonary syndrome has also been reported in cases of mild hepatic dysfunction or noncirrhotic portal hypertension, indicating that portal hypertension also plays a part in the pathogenesis. Liver transplantation remains the only therapeutic option of proven benefit. We describe 2 cases of hepatopulmonary syndrome in the setting of inferior vena cava (suprahepatic) obstruction, but with minimal hepatic dysfunction. After balloon cavoplasty, 1 patient showed, in addition to improvement of the features of hepatic outflow obstruction, significant reduction of dyspnea, cyanosis, and hypoxemia with arterial blood gas normalization within 2 weeks and intrapulmonary shunt reversal within 8 weeks. This implies that hemodynamic alterations (such as portal hypertension) independently contribute to the pathogenesis of hepatopulmonary syndrome in at least some of the cases. Therapies aimed at correcting these abnormal hemodynamics may be important in the treatment of this condition, especially when the hepatic functional status by itself does not warrant a liver transplant.

Adult↗
PubMed2000

Clinical and haemodynamic aspects of hepatopulmonary syndrome in Indian patients with cirrhosis.

BACKGROUND: Hepatopulmonary syndrome consists of the triad of hepatic dysfunction and/or portal hypertension, intrapulmonary vascular dilatation and hypoxaemia, in the absence of detectable primary cardiopulmonary diseases. In the present study, we examined the frequency of hepatopulmonary syndrome among Indian patients with cirrhosis, and studied clinical predictors and pulmonary haemodynamic alterations. METHODS: Forty-five patients with cirrhosis and no cardiopulmonary diseases were investigated by air-contrast echocardiography. Where patients were positive, arterial blood gas analysis was carried out. Positive contrast echocardiography with PO2 < 70 mmHg confirmed the diagnosis of hepatopulmonary syndrome. Three cases with the syndrome and 24 without were assessed for haemodynamic status by hepatic and pulmonary catheterization. RESULTS: Four of 45 cases of cirrhosis (8.9%) had positive contrast echocardiographies, including three (6.7%) with hepatopulmonary syndrome and one 'subclinical' case (positive contrast echocardiography without hypoxaemia). Under haemodynamic study, the mean pulmonary arterial and pulmonary capillary wedge pressures appeared to be lower among those patients with hepatopulmonary syndrome. CONCLUSIONS: In this small study, the frequency of hepatopulmonary syndrome was relatively low (6.7%). Cyanosis was the only reliable clinical indicator, and there was no clear relationship with the severity of cirrhosis by Child's grading.

Adolescent↗
PubMed2000

Propranolol in primary and secondary prophylaxis of variceal bleeding among cirrhotics in India: a hemodynamic evaluation.

OBJECTIVE: In the present study, we attempted to complete the hemodynamic assessment of propranolol response in cirrhotics with esophageal varices at high risk of bleeding, in one sitting, so as to identify nonresponders at the earliest. Some noninvasive indicators of this response were also evaluated. METHODS: Hepatic venous pressure gradient (HVPG) was measured in 33 such cases (18 nonbleeders, 15 bleeders) before and 90 min after an oral dose of 80 mg propranolol, and reduction by > or =20% taken as responder. RESULTS: Twenty-two patients (66.67%) responded (HVPG reduction > or =26%), whereas 11 (33.33%) did not (HVPG reduction < or =6%). Postdrug HVPG between responders and nonresponders showed a significant difference (p < 0.001). Neither baseline HVPG (p > 0.1), baseline CI (p = 0.665), nor baseline stroke volume index (p > 0.1) could predict responder status. Difference of HVPG reduction (percent) between bleeders (21.49 +/- 35.53) and nonbleeders (40.58 +/- 23.95) approached, but did not reach, statistical significance (p = 0.076). However, logistic regression showed this difference to be significant (p = 0.026). Age of responders was found to be significantly lower than that of nonresponders (p approximately equals 0.05). During a follow-up of 9-38 months, only one of 22 responders (on propranolol) had an episode of variceal bleed. None in whom HVPG fell to < or = 12 mm Hg bled. CONCLUSION: The study suggests that single-sitting hemodynamic assessment of acute response to high-dose oral propranolol clearly differentiates between responders and nonresponders. Moreover, it appears that prior history of variceal bleeding and old age negatively influences the effect of propranolol.

Administration, Oral↗
PubMed2000

Etiology based prevalence of Budd-Chiari syndrome in eastern India.

BACKGROUND: Diagnosis of Budd-Chiari syndrome (BCS) is often missed unless its possibility has been kept in mind. Obstruction of inferior vena cava (IVC) is reportedly the most frequent cause of BCS in Afro-Asian variety. AIM: An attempt was made to classify BCS (in an eastern Indian population) etiopathologically. PATIENTS AND METHODS: Thirty consecutive cases of BCS presenting over a period of five years were included. Following a thorough physical examination, necessary investigations (including coagulation profile, ultrasonography (with Doppler study) of hepatobiliary tract, hepatic vein and IVC angiography (n = 22) and liver biopsy (n = 26, including autopsy in two cases) were performed. RESULTS: Mean age at presentation was 32.7 +/- 10.36 years (range 12-60 years) with M:F = 21:9. Clinical presentations included, hepatomegaly in 28 (93.3%), ascites in 27 (90%), splenomegaly in 15 (50%), pain in abdomen in 26 (86.6%), jaundice in 10 (33.3%), back veins in 20 (66.6%) and gastrointestinal bleeding in three (10%) cases. Amongst the total of 30 patients, four, six and 20 cases presented as fulminant, acute and chronic BCS respectively. Twenty four cases of BCS could be diagnosed by ultrasonography alone, while the remainder required angiography for diagnosis. IVC and hepatic vein angiography revealed membranous obstruction in nine, partial stricture of IVC in six, and IVC and/or hepatic vein block in others. The etiopathological nature in 30 cases were as follows: idiopathic membranous obstruction in nine (30%), hepatocellular carcinoma in six (20%), idiopathic stricture in six (20%) cases and one case (3.3%) each of the following: cholangiocarcinoma, renal cell carcinoma, chronic pancreatitis, hydatid cyst in liver, protein S deficiency, oral contraceptive use, nephrotic syndrome (with antithrombin III deficiency), polycythemia rubra vera and chronic lymphatic leukemia. CONCLUSION: Idiopathic membranous obstruction and stricture of IVC are the commonest cause of BCS in the eastern part of India. Hepatocellular carcinoma is also a common cause, presenting in the fulminant form. Ultrasonography may be a helpful screening test for BCS, but IVC and hepatic vein catheterisation is essential for a complete work up of these patients.

Adolescent↗
PubMed1999

Endoscopic variceal ligation for primary prophylaxis of oesophageal variceal bleed: preliminary report of a randomized controlled trial.

BACKGROUND: Prevention of variceal bleeding, a major cause of morbidity and mortality, is an important goal in the management of patients with portal hypertension (PHT). Although propranolol has been found useful in preventing the first episode of variceal bleeding (primary prophylaxis) in cirrhotic PHT, it has limitations which include side effects, contraindications, non-compliance and failure in some patients. Endoscopic variceal ligation (EVL) has not been used for primary prophylaxis. METHODS: Thirty cirrhotic patients with PHT, grade III to IV oesophageal varices, hepatic venous pressure gradient > or = 12 mmHg and no prior history of upper gastrointestinal bleeding were randomized to receive propranolol (to reduce their pulse rate by 25% from baseline, n = 15) and EVL (weekly to fortnightly until variceal eradication, n = 15). The two groups were comparable. All the patients in EVL group had variceal eradication during 3.8 +/- 2.2 sessions. RESULTS: There was no major complication or interval bleeding. During a follow-up period of 17.6 +/- 4.7 months, varices recurred in three, two of which bled (successfully treated by EVL). In contrast, during this period of follow up one patient in the propranolol group had variceal bleeding (P=NS). Side effects of propranolol included symptomatic bradycardia requiring reduction of dose in one of 15 patients. CONCLUSIONS: Although sample size in this study is small, it seems that EVL may be a good option for primary prophylaxis for variceal bleeding in patients with cirrhotic PHT; further studies on a larger number of patients and longer follow up are required.

Adrenergic beta-Antagonists↗
PubMed1995

Risk factors and angiographic profile of coronary artery disease in young.

A total of 124 patients of ischaemic heart disease under 40 years of age (96 with myocardial infarction and 28 with angina) were studied for risk factors of coronary artery disease. Electrocardiogram, treadmill test, lipid profile and coronary arteriography were done in all cases. Smoking (56.4%) and hyperlipidaemia (30.6%) emerged as the major risk factors. Further stratification of lipid profile revealed that predictive value of hypercholesterolaemia could be enhanced by considering the different ratios of lipoproteins and indices of atherogenicity. Coronary arteriography revealed a preponderance of single vessel disease (48.4%)-left anterior descending being most commonly involved (71.8%). Increase in low density lipoprotein fraction was related to multivessel involvement.

Adult↗
PubMed1994

Effect of intravenous streptokinase on left ventricular function following acute myocardial infarction--an echocardiographic study.

160 patients with first attack of acute myocardial infarction (AMI), admitted within 6 hours after onset of chest pain, were divided into two groups--80 receiving intravenous streptokinase (IVSK, Gr. I) an 80 being treated without IVSK (GR. II). They were studied for pre-discharge (12.5 +/- 2.5 days-post admission) echocardiographic LV function. Gr. I pts received 1.5 million units of IVSK within 6 hrs of onset of chest pain, alongwith beta-blockers, aspirin and heparin unless contraindicated. Gr. II received all these except IVSK alongwith conventional therapy. Highly significant (P < 0.001) improvement was noted in the end-diastolic volume (EDV), end-systolic volume (ESV), Ejection fraction (EF) and regional wall motion score (RWMS) in the anterior wall (AW) AMI group when treated early with IVSK. In the inferior wall (IW) AMI group significant decrease was observed in the EDV and ESV (P < 0.001) and RWMS (P < 0.05), but the difference was not statistically significant for EF. Early high-dose short term IVSK infusion is thus associated with highly significant improvement in LV functions--regional as well as global--especially in AW AMI; in IWAMI the improvement is less marked.

Echocardiography↗