Mechanical response of polyacrylamide breast tissue phantoms: Formulation, characterization and modeling.

In the context of breast cancer detection, mechanical imaging is an emerging technique for screening breast cancer. In view of its promise, it deserves a detailed investigation. Development of material that can emulate tissue behavior is essential for research. This work is concerned with the fabrication of polymeric specimens to capture the mechanical behavior of human breast tissues. Three types of tissue phantoms are fabricated: fat, glandular and ductal carcinoma tissues. The fabricated phantoms are compared to available human breast tissue data obtained through compression tests and stress relaxation tests. Further, the fabricated tissue phantoms are subjected to stress relaxation tests to characterize their viscoelastic response. A finite strain viscoelastic constitute model is proposed to describe the mechanical response of the breast tissue phantoms. The model is calibrated using experimental data for phantom tissue specimens. Both phantom tissue specimens and model predictions show reasonable trends. The phantom tissues and model may be of utility in developing mechanical imaging setups.

Evaluation of the immunogenicity and safety of an indigenously developed DTwP-Hib tetravalent combination vaccine (Shan 4) with EasyFourTM in Indian infants administered per EPI schedule: a phase III trial.

The study was planned to assess and compare immunogenicity and safety of an indigenous DTPw-Hib combination vaccine (Shan 4) with EasyFour, the available DTwP-Hib vaccine in India. Overall 210 healthy infants, six to eight weeks of age, were randomized to receive three doses of either Shan 4 or EasyFour at 6, 10 and 14 weeks of age. Antibodies were analyzed prior to and four to six weeks post third vaccine dose. Solicited and unsolicited local and systemic events in the follow up period after each dose were recorded. Post vaccination 100% of the infants in Shan 4 and EasyFour groups had seroprotective concentrations of Anti PRP-T IgG antibodies, IgG anti-diphtheria toxoid antibodies and IgG anti-tetanus toxoid antibodies. Following third dose of vaccination 86.99% subjects in the Shan 4 group and 73.85% subjects in the EasyFour group seroconverted for anti-pertussis antibody titres. Two Serious Adverse Events (SAE s) were reported during the course of the study, all unrelated to the respective vaccine administered. Most commonly reported adverse events in both the groups were pain at injection site, mild fever (<103°F) and minor swelling at injection site. The study proved that Shan 4 was safe and immunogenic compared to the available licensed vaccine.

Cardiac beriberi: often a missed diagnosis.

Thiamine deficiency leads to various manifestations due to dysfunction of nervous or cardiovascular system, commonly known as dry and wet beriberi, respectively. The latter, also known as cardiac beriberi is usually missed in clinical practice because of the absence of classically described symptoms such as pedal edema/anasarca. We investigated 55 such infants and prospectively followed their clinical course. All the babies were exclusively breast-fed and their mothers belonged to low socio-economic status with their staple diet consisting of non-parboiled polished rice. Majority presented with tachypnea, chest indrawing and tachycardia and cardiomegaly with dilatation of right heart and pulmonary hypertension on 2D-echocardiography. Low levels of erythrocyte transketolase activity suggested thiamine deficiency that was confirmed by reversion of several clinical features including cardiologic abnormalities to normalcy on thiamine supplementation. We recommend thiamine therapy for infants with unexplained congestive cardiac failure or acute respiratory failure from precarious socio-economic background since it is life-saving in many instances.

G6036A substitution in mitochondrial COX I gene compromises cytochrome c oxidase activity in thiamine responsive Leigh syndrome patients.

Cytochrome c oxidase (COX) deficiency is known to be associated with Leigh syndrome (LS), however there are limited studies on genetic screening of mitochondrial (mt) DNA encoding COX genes as well as the functional validation of identified variants. In our previous studies, we cared for total 165 LS patients and analyzed the nucleotide variations across entire mt genome. We observed a high level of genetic heterogeneity in these patients. We identified various reported and novel variation across entire genome including COX genes. In our present study we have further studied and functionally validated the selected novel nucleotide variant of COX I and COX II gene using different in-silico tools and trans mitochondrial cybrid based assays. As a result of our study, G6036A (G45S) variant of COX I gene, reduced the COX activity in both spectrophotometric as well as In-gel BN-PAGE assays. FACS analysis also revealed this variant to affect the mitochondrial membrane potential in the respective cybrids. Interestingly most of our in-silico studies indicated that this variant might affect the secondary structure and confirmation of COX I protein. Thus we report the first missense mutation in the COX I gene of LS patients and justify its pathogenic role in these patients by different assays. Variant A7746G (N54K) in COX II gene was also predicted to affect the secondary structure as well as stability of COX II protein. Though, the effect of this variant was not significant, however it will be interesting to investigate its significance by other assays in future.

Novel p.P298L SURF1 mutation in thiamine deficient Leigh syndrome patients compromises cytochrome c oxidase activity.

SURF1 is a nuclear gene and encodes for an important assembly factor for cytochrome c oxidase enzyme. A number of mutations in SURF1 gene render cytochrome c oxidase deficiency, a major causative factor for Leigh syndrome. We screened all the 9 exons and exon-intron boundaries of SURF1 gene in 165 Indian Leigh syndrome patients who were thiamine responsive too. Consequently, we identified several novel and reported nucleotide variations in this gene. The nucleotide changes were analysed by using different in-silico tools for predicting their pathogenicity. Based upon the predictions, we further validated the analyzed functional significance of p.N249D and p.P298L mutations in SURF1 protein using COS-7 cells. Though, both the mutations did not affect the localization of SURF1protein into the mitochondria. But, interestingly the novel mutation p.P298L was reported to significantly compromise the COX activity in these cells.

Genetic heterogeneity of mitochondrial genome in thiamine deficient Leigh syndrome patients.

In our previously published study, we cared for 165 thiamine deficient Leigh syndrome (LS) patients who presented in acute life threatening conditions with severe neurological abnormalities. However the molecular basis for this atypical phenotype was not explored. This study is an effort to undermine the possible molecular defects in mitochondria of those patients and put-forth an explanation towards this clinical presentation. Protein coding genes of mitochondrial (mt) DNA were sequenced in total 165 LS patients and 94 age matched controls. To understand their pathogenic significance, nucleotide variations were also studied using various in-silico tools. Histochemical and electron microscopic analysis was also done in tissue samples obtained from 23 patients. We observed a very high level of genetic heterogeneity across the mt DNA of all these patients. In the concordance of published literature we also observed a large number of variations in ND5 gene (hot spot for LS). We also observed a total 13 nucleotide variations across COX genes, which is otherwise not common in LS. As per in-silico analysis, many of these variations were suggested to be pathogenic. Histochemical and electron microscopic studies also suggested the defects in the mitochondria of these patients. As these patients were thiamine deficient, hence we propose that genetic defects and thiamine deficiency may together severely affect the ATP levelof these patients, leading to acute and life threatening clinical presentation. Present study has opened up many avenues for further research towards understanding the genetic basis and possible role of thiamine deficiency in LS patients.

High prevalence of infantile encephalitic beriberi with overlapping features of Leigh's disease.

Infantile encephalitic beriberi (IEBB) is a rare form of thiamine deficiency and is poorly described. A proportion of Leigh's disease (LD) patients have similar clinical picture and response to thiamine as beriberi, leading to confusion in diagnosis and management. Data on IEBB and LD is scarce and status of thiamine deficiency in India is controversial. We report several infants with life-threatening respiratory and central nervous system symptoms that overlap between IEBB and LD. Majority had low erythrocyte transketolase levels and responded dramatically to thiamine supplementation suggesting a diagnosis of IEBB. However, presence of characteristic lesions on brain imaging and residual damage in several patients on follow-up does not rule out LD completely. Our study highlights the importance of thiamine deficiency in India, especially in the breast-feds and its overlapping features with LD. Awareness of this common mode of presentation may save patients' lives by early diagnosis and timely thiamine supplementation.

Tuberculous Dactylitis: An Uncommon Presentation of a Common Infection.

Tuberculous dactylitis is an unusual form of osteoarticular tuberculosis involving the short tubular bones of hands and feet, which is uncommon beyond six years of age. We report the case of a fifteen-year-old adolescent boy who was diagnosed with tuberculous dactylitis, involving contralateral hand and foot. His diagnosis was delayed due to lack of suspicion of this rare entity. The report also examines the diagnostic difficulties faced by clinicians in arriving at an appropriate diagnosis.

In vivo evaluation of 99mTc-DTPA and 99mTc-sulphur colloid as tracers in colonic drug delivery systems using gamma scintigraphy in volunteers.

PURPOSE: The suitability of 99mTc-diethylenetriaminepenta- acetic acid (DTPA) and 99mTc-sulphur colloid (99mTc-SC) as tracers in gamma scintigraphy for the evaluation of colon-specific drug delivery systems was assessed in healthy volunteers. METHOD: Sodium chloride core tablets containing either 99mTc-DTPA or 99mTc-SC were prepared and compression coated with two different quantities of guar gum. The compression-coated tablets were subjected to gamma scintigraphic studies for colonic drug delivery in healthy human volunteers. RESULTS: The tablets containing 99mTc-DTPA did not release the tracer in stomach and small intestine, and on entering the colon disintegrated completely whereas the tablets containing 99mTc-SC remained intact in stomach, small intestine and in colon as well. The study showed that DTPA is a suitable tagging agent for 99mTc in the evaluation of guar gum based colonic drug delivery systems containing water-soluble drugs. CONCLUSION: In the present investigation guar gum was applied externally as a compression coat over the radiolabelled core. Since the core consisted of water-soluble material (sodium chloride), it is possible that the release of the tracer from the 99mTc-DTPA containing formulations is a combined effect of enzymatic action and diffusion of the salt. The failure of disintegration of 99mTc-SC containing formulations might be due to its interference with the disintegration or the part diffusion observed with 99mTc-DTPA cores. The results of the study showed that DTPA is a suitable tagging agent for 99mTc in the evaluation of colonic drug delivery systems containing water-soluble drugs by gamma scintigraphy.