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Biomedical subjects

S Saha

Publications and source records attributed to S Saha.

At least 289 records · Page 16Linked to original sources
PubMed1972

Chronic Budd-Chiari syndrome due to obstruction of the intrahepatic portion of the inferior vena cava.

Clinical features of obstruction of the intrahepatic portion of the inferior vena cava were observed in five out of the 11 patients with the Budd-Chiari syndrome seen during the last four years. These patients apparently formed a distinct group from the remaining six and resembled in clinical course, biochemical features, haemodynamic findings, and radiological investigations the patients described as cases of membranous obliteration of the intrahepatic portion of the inferior vena cava. The present study reports five such patients diagnosed with the help of venous catheterization, percutaneous hepatography, and haemodynamic studies. The value of distinguishing these patients from those with obstruction due to hepatic vein occlusion is highlighted because of the difference in the prognosis and treatment.

Adolescent↗
PubMedDate not supplied

Mechanical characterization of commercially made carbon-fiber-reinforced polymethylmethacrylate.

Acrylic bone cement is significantly weaker and of lower modulus of elasticity than compact bone. It is also weaker in tension than in compression. This limits its use in orthopedics to areas where tensile stresses were minimum. Many authors have shown that addition of small percentages of fiber reinforcement by hand mixing improved the mechanical properties significantly but with variable results. In this investigation we have examined the mechanical properties of machine-mixed, commercially available carbon-fiber-reinforced bone cement. Appropriate samples of normal low-viscosity cement and carbon-fiber-reinforced cement were prepared and tested mechanically. Carbon fiber increased the tensile strength and modulus by 30% and 35.8% respectively. The compression strength and modulus, however, increased by only 10.7%. Similarly, bending and shear strengths improved by 29.5% and 18.5%, respectively. Diametral compression strength, which is an indirect measure of tensile strength, however, showed only 6.2% improvement. The maximum temperature rise during polymerization was also reduced significantly by the fiber reinforcement.

Bone Cements↗
PubMedDate not supplied

The electrical and dielectric properties of human bone tissue and their relationship with density and bone mineral content.

In this study, we examined the electrical properties of wet human cortical and cancellous bone tissue from distal tibia and their relationship to the wet, dry, and ash tissue densities. The resistivity and specific capacitance of both cortical and cancellous bone were determined for different frequencies and directions (orientation). The wet, dry, and ash tissue densities of the bone samples were measured, and the ash content was determined. Correlation and regression analysis was used to examine the possible relationships among the electrical properties and the tissue densities for cancellous and cortical bone specimens separately as well as for all of the bone specimens combined. Highly significant positive correlations (p < 0.001) were found between the wet density of bone and the dry and ash densities. The specific capacitance of the cancellous bone specimens in all three orthogonal directions showed significant (p < 0.01) positive correlations with the wet, dry, and ash densities. In general, the specific capacitance depended more on density for all bone specimens, and only a weak relationship was found between the resistivity of human cortical bone and density.

Aged↗
PubMedDate not supplied

Localizing the sentinel node outside of the specialty center: success of a lymphatic mapping course in disseminating new technology.

BACKGROUND: Sentinel node biopsy (SNB) is an evolving technology in the management of breast cancer. The purpose of this study was to determine the success of an SNB course in emphasizing principles for participants to successfully initiate an SNB program at their institution. METHODS: Participants in a university-sponsored course were queried 6 to 18 months after the course regarding their success in initiating SNB in their practice. Univariate analysis was used to determine the likelihood of implementing a SNB program. RESULTS: Ninety-one participants responded. Of these respondents, 56 had initiated an SNB program at their hospital, and 20 had completed a "validation" phase. "Validation" consisted of less than 10 cases for 11 respondents, 11 to 20 cases for 5 respondents, and 20 to 30 cases for 3 respondents and >30 cases for 1 respondent. Twenty-eight percent initiated the learning curve without an Institutional Review Board (IRB) protocol, and a further 20% went on to utilize SNB without axillary dissection in sentinel node-negative patients without IRB approval. Univariate analysis revealed that surgeons practicing in a group whose caseload consisted of more than 25% breast surgery cases were most likely (P < 0.05) to implement SNB in their practice. CONCLUSIONS: Success in applying SNB after a course is high among surgeons in groups with a significant breast caseload, although recommendations for obtaining institutional approval and completing a 30-case validation series are often disregarded.

Academic Medical Centers↗
PubMedDate not supplied

Blood cultures from Bangladeshi children with septicaemia: an evaluation of conventional, lysis-direct plating and lysis-centrifugation methods.

The use of a laboratory-made lysis-direct plating and lysis-centrifugation (LDP/LC) device for blood cultivation has been compared with the conventional broth culture method in respect of speed and sensitivity in detecting organism(s) and cost effectiveness. 400 blood cultures yielded 95 clinically significant isolates. Both methods recovered 73 organisms (76.8%); 20 (21%) were detected by LDP/LC methods only, and 2 (2.1%) were isolated by the conventional method only. All the 93 isolates (97.8%) recovered by LDP/LC were isolated within 48 h, whereas the broth culture method took 7 d to isolate a total of 75 organisms (78.9%). The LDP/LC method, with our laboratory-made device, costs one-fourth of the cost of the conventional broth culture system.

Bacteriological Techniques↗
PubMedDate not supplied

Synthesis and anti-Pneumocystis carinii pneumonia activity of novel dicationic dibenzothiophenes and orally active prodrugs.

Dicationic carbazoles have been found to be highly active against a rat model of Pneumocystis carinii pneumonia (PCP). Unfortunately, amidoxime derivatives, designed as prodrugs, were inactive against PCP even though the corresponding amidines were highly active. In the present work, a series of 2,8- and 3,7-bis cationic dibenzothiophenes was synthesized and assayed for anti-PCP activity. Three of the compounds proved to be more potent and less toxic than a standard anti-PCP drug (pentamidine) when given intravenously. Unlike the carbazoles, a dibenzothiophene amidoxime prodrug given orally reduced the parasite load by more than 99%. While no quantitative correlation was seen between anti-PCP activity and DNA binding, a strong level of DNA binding was found to be necessary for antimicrobial activity.

Animals↗
PubMedDate not supplied

Aflatoxin B1 contamination in maize samples collected from different geographical regions of India--a multicentre study.

Under a multicentre study conducted by the Indian Council of Medical Research, 2,074 samples of maize were collected from rural and urban areas of 11 states representing different geographical regions of the country. These samples were analysed for aflatoxin B1 using the AOAC method. Analytical quality assurance between various participating laboratories was ensured through analysis of check-samples. About 26% of maize samples collected from 11 states exceeded the permissible Indian regulatory limit of 30 micrograms kg-1. No statistically significant difference in percentage of samples contaminated (> 30 micrograms kg-1) was observed between pooled rural (27.8%) and urban (23.7%) data. The maximum level of contamination of 666 micrograms kg-1 was observed in the state of Haryana. The median level of < 5 micrograms kg-1 was observed in the states of Gujarat, Haryana, West Bengal, Andhra Pradesh and Karnataka. In all other states studied, the median level was found to vary between 10 and 35 micrograms kg-1.

Aflatoxin B1↗
PubMedDate not supplied

Chromosomal assignment of microsatellite loci in cotton.

Microsatellite markers or simple sequence repeats (SSRs) represent a new class of genetic markers for cotton (Gossypium sp.). Sixty-five SSR primer pairs were used to amplify 71 marker loci and genotype 13 monosomic and 27 monotelodisomic cotton cytogenetic stocks. Forty-two SSR loci were assigned to cotton chromosomes or chromosome arms. Thirty SSRs were not located to specific chromosomes in this study. Nineteen marker loci were shown to occur on the A subgenome and 11 on the D subgenome by screening accessions of G. herbaceum (2n = 2x = 26 = 2A1) and G. raimondii (2n = 2x = 26 = 2D5). The aneuploid stocks proved to be very powerful tools for localizing SSR markers to individual cotton chromosomes. Multiplex PCR bins of the SSR primers and semiautomated detection of the amplified products were optimized in this experiment. Thirteen multiplex PCR bins were optimized to contain an average of 4 SSR primer pairs per bin. This provides a protocol for high-throughput genotyping of cotton SSRs that improves the efficiency of genetic mapping and marker-assisted programs utilizing SSR markers.

Alleles↗
PubMedDate not supplied

Simple sequence repeat (SSR) markers linked to the Ligon lintless (Li(1)) mutant in cotton.

Ligon lintless (Li(1)) is a monogenic, dominant mutant in cotton, whose expression results in extreme reductions in fiber length on mature seed. The objectives of this research were to compare fiber initiation between the Li(1) mutant and TM-1 to reveal the fiber initiation differences between normal and mutant phenotypes, to develop a linkage map of simple sequence repeat (SSR) markers with the Li(1) locus, and to identify the chromosomal location of the Li(1) locus. Comparative scanning electron microscopy studies of fiber development in a normal TM-1 genotype and the near-isogenic Li(1) mutant at 1 and 3 days postanthesis revealed little differences between the two during early stages of development, suggesting that Li(1) gene expression occurs later, probably during the elongation phase. Thirty-eight SSR loci were found to be polymorphic between TM-1 and Li(1) and were used for mapping in an F(2) population. Twenty-two SSR loci, along with Li(1), were located on eight linkage groups, covering a total genetic distance of 218.3 cM. Analysis of individual monosomic and monotelodisomic plants indicated that two SSR loci (MP4030 and MP673) from the Li(1) linkage group were located on chromosome 22.

Chromosome Mapping↗
PubMedDate not supplied

Ethical responsibilities of the clinical engineer.

Because of the growth of medical technology, Clinical Engineers have increased responsibilities in respect to this new technology and so to modern medicine itself. This results in a need to ensure that an ethical consciousness of responsibilities to patients, physicians, and institutions grows within Clinical Engineers as they move into evermore important roles within the health care system. Clinical Engineers must have clearly defined roles, as well as authority acknowledged and supported by other health care professionals. Most importantly, Clinical Engineers themselves must recognize the seriousness of their professional responsibilities as they contribute to the maintenance of equipment, use and design instrumentation, and fulfill roles in administration, management, and research. As members of the health care team, Clinical Engineers must be prepared to face ethical issues arising from defective or inadequate equipment, hazards and incidents, scarcity and resources, conflict of interest, confidentiality, clinical research, "truth-telling," and care of the terminally ill.

Biomedical Engineering↗
PubMedDate not supplied

Role of the central nucleus of the amygdala in the control of blood pressure: descending pathways to medullary cardiovascular nuclei.

1. One of the key areas that links psychologically induced stress with the blood pressure-regulatory system is the central nucleus of the amygdala (CeA). This is an integratory forebrain nucleus that receives input from higher centres in the forebrain and has extensive connections with the hypothalamus and the medulla oblongata, areas involved in the regulation of the cardiovascular reflexes. 2. Based on studies using electrical or chemical stimulation or electrolytic lesions of the CeA, it has become clear that the CeA plays an important role in the regulation of blood pressure in response to stressful or fearful stimuli. 3. Two important medullary areas known to receive projections from the CeA are the nucleus tractus solitarius (NTS) and the rostral ventrolateral medulla (RVLM). The NTS is the site of the first synapse for afferent fibres originating from baroreceptors, chemoreceptors and the heart, whereas the RVLM contains neurons that maintain resting blood pressure and sympathetic nerve activity via projections to sympathetic preganglionic neurons in the intermediolateral cell column of the thoracolumbar spinal cord. 4. Electron microscopic studies using combined anterograde tracing and pre- and post-embedding immunogold labelling have shown that the pathways originating from the CeA to the NTS are inhibitory and may use GABA as a neurotransmitter. The results of these studies suggest that blood pressure changes produced by activation of the CeA may be mediated by attenuation of baroreceptor reflexes through a GABAergic mechanism at the level of the NTS. 5. Neuronal tract tracing combined with neurofunctional studies using the Fos protein as a marker of activated neurons indicate that the CeA projects directly to baroreceptive neurons in the NTS and RVLM that are activated by changes in blood pressure. 6. In conclusion, studies that have examined the efferent pathways of the CeA suggest that CeA neurons with projections to medullary baroreceptive neurons may play a vital role in the reflex changes in sympathetic nerve activity that are involved in blood pressure regulation in response to stress or anxiety.

Amygdala↗
PubMedDate not supplied

Quantitative determination of tolerance doses for preoperative and postoperative radiotherapy of bones.

A method has been developed for the quantitative determination of the tolerance doses for preoperative and postoperative radiotherapy of bones in New Zealand white rabbits. The midshaft osteotomy was carried out on both ulnae of each rabbit. Localized radiation of 2000, 3000, and 4000 rad (20, 30, and 40 Gy) was given in daily fractions of 500 rad to different groups of rabbits. The diaphyseal area of one forearm of each rabbit was irradiated and the other forearm was used as a control. After healing, the mechanical strength of each ulna was measured. The end point is defined as "strength reduction dose-63" (SRD63), i.e., the dose which would be expected to reduce the mechanical strength of the irradiated, fractured, and healed bone compared with the contralateral unirradiated diaphysis by 63%. The SRD63's for preoperative and postoperative radiotherapy were 4350 rad (43.5 Gy) and 6200 rad (62 Gy), respectively, with a 500 rad (5 Gy)/fraction schedule. Through the use of the nominal standard dose (NSD) formula at 300 rad (3 Gy)/fraction and five fraction per week, these SRD63's are equivalent to 5700 rad (57 Gy) and 8100 rad (81 Gy), respectively.

Animals↗
PubMedDate not supplied

Molecular variants of red cell glucose-6-phosphate dehydrogenase deficiency in Central Java, Indonesia.

One hundred and sixty-nine Javanese males were screened for the presence of red cell glucose-6-phosphate dehydrogenase (G6PD) variants by a dye decoloration screening test and starch gel electrophoresis. The frequency of G6PD deficiency was 14%. Three non-deficient electrophoretic variants with mobilities of 95, 105 and 107% of GdB+ were encountered. Sixteen G6PD-deficient subjects were further investigated for the presence of mutations at nt95 A-->G, nt487 G-->A, nt493 A-->G, nt563 C-->T, nt1024 C-->T, nt1376 G-->T, nt1388 G-->A and the silent mutation (nt1311 C-->T) of the G6PD gene by natural or artificially created amplified restriction sites. They were identified by the polymerase chain reaction and electrophoresis of restriction-digested products. Five subjects had the Mediterranean mutation (nt563 C-->T), but only one had simultaneous presence of nt1311(T). The next common mutations were 1376(T) in three subjects and 487(A) in two subjects. Five of the sixteen subjects had the nt1311(T) mutation giving an overall frequency of 0.31. The other four mutations were absent in this population sample.

Base Sequence↗