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Biomedical subjects

A Tiwari

Publications and source records attributed to A Tiwari.

At least 19 recordsLinked to original sources
PubMed2006

Permissibility of different cell types for the growth of avian metapneumovirus.

Vero cells are commonly used for the growth of avian metapneumovirus subtype C (aMPV-C). This study was conducted to evaluate 17 different cell types for the growth of a Minnesota strain of aMPV-C. The virus was inoculated into these cell types and virus growth was monitored by the development of cytopathic effects (cpe) and immunofluorescence. Virus growth was obtained in 6 of 17 cell types tested with the highest virus titers observed in BGM and DF-1 cells. The flow cytometric analysis of cells at 72 h post inoculation found the highest number of infected cells in BGM cells followed by QT-35 cells. At 48 h post inoculation, DF-1 and BGM cells showed the highest number of infected cells. These results suggest that BGM, QT-35, and DF-1 cells can be used for high titer propagation of aMPV-C.

Animals↗
PubMed2006

Attempts to improve on a challenge model for subtype C avian pneumovirus.

Respiratory disease caused by avian pneumovirus (APV) has a strong negative impact on the economy of the turkey industry in many countries. Progress in developing vaccines against this infection in the US has been slow partly because of the lack of a consistent challenge model to conduct vaccine efficacy studies. This study was designed to determine whether in vivo passages of a US isolate of APV, designated subtype C (APV-C), would increase virus virulence, leading to consistent clinical signs in turkeys. Three different experiments were performed. In experiments 1 and 2, a cell culture adapted APV was passaged four times in vivo in turkeys. Following each passage, clinical signs were found to increase in severity. In addition, inoculated birds were found to shed both APV RNA (by reverse transcriptase-polymerase chain reaction) and live virus (by virus isolation) at each passage. The mean antibody titres also increased with each passage. The results of the second experiment were not in complete agreement with those of experiment 1. In the third experiment, APV grown in three different cell lines was inoculated into three groups of turkeys. Clinical signs were observed in inoculated birds and virus could be isolated from all three groups. The results of this preliminary study indicate that in vivo passage of APV-C in birds may increase virus virulence, but the results obtained in experiment 2 suggest that further studies are needed to confirm this.

Animals↗
PubMed2006

Survival of two avian respiratory viruses on porous and nonporous surfaces.

The transmission of pathogens from infected to susceptible hosts may occur through contaminated fomites and inanimate objects. This type of transmission depends on the ability of the pathogens to survive in the environment. In this report, we describe the survivability of two avian respiratory viruses, e.g., avian metapneumovirus and avian influenza virus on 12 different porous and nonporous surfaces. The viruses survived on some of the surfaces for up to 6 days postcontamination but not after 9 days. Both viruses survived longer on nonporous surfaces than on porous ones. One of the reasons for poor survival on porous surfaces could be inefficient elution of virus from these surfaces. These results should be helpful in determining how long the premises should be left vacant after an outbreak of these viruses has occurred in poultry houses.

Animals↗
PubMed2005

Management of lower limb lymphoedema in the United Kingdom.

OBJECTIVE: Many investigations and treatments exist for lower limb lymphoedema. We undertook a survey on the management of this condition by vascular surgeons and the resources available for its treatment in the UK. DESIGN: A questionnaire was designed to assess the management of lymphoedema. MATERIALS AND METHOD: A postal questionnaire was sent to all members of the The Vascular Society of Great Britain and Ireland. RESULTS: 251/440 (57%) consultant surgeons returned a completed questionnaire comprising 45.3% teaching hospital and 54.7% district general hospital (DGH) consultants. 77.9% of the consultants saw less than 10 patients annually with lymphoedema. The commonest causes of lymphoedema were primary lymphoedema (99.3%) and malignancy (37.1%). Lipoedema, a cause of limb swelling was only seen or recognised by 46.2% of the consultants. The commonest investigations performed were a duplex scan, lymphoscintigram, full blood count and urea and electrolytes. The common methods of confirming lymphoedema were either by lymphoscintigram (54.5%) or from a diagnosis of exclusion (33.7%). Lymphoedema physiotherapy was available only to 53.8% of the consultants. Surgery was performed by 10.5% of consultants. 73.4% of the consultants believed that lymphoedema is managed inadequately and 72.9% believed that resources are insufficient in the UK for this condition. CONCLUSION: In the UK the majority of vascular consultants see less than 10 patients annually with lymphoedema. Very few patients undergo confirmation of this diagnosis with non-invasive investigation and very few consultants perform surgery. Management of this condition is perceived by the consultants to be poor, with a lack of resources and particular shortage of lymphoedema physiotherapists. Centralisation of these services may be a way of improving this condition.

Diagnosis, Differential↗
PubMed2005

Growth of vaccine strains of avian pneumovirus in different cell lines.

The isolation of avian pneumovirus (APV) (avian metapneumovirus) is usually performed in embryonated chicken eggs or chicken embryo fibroblast cell cultures followed by adaptation in continuous cell lines such as Vero cells. This study was conducted to find a suitable cell line that could be used to propagate vaccine strains of APV to high titre. For this purpose, we compared the growth of two Vero cell-adapted vaccine strains of APV (P63 and ca-APV) in seven different cell types with their growth in Vero cells. The cell types used were BGM-70, MA-104, QT-35, BHK-21, McCoy and DF-1 cells and primary turkey embryo fibroblast cells. When compared with growth in Vero cells, both viruses yielded higher titres in BGM-70 cells, while P63 also produced higher titres in MA-104 cells. In another experiment, the two viruses were grown and titrated in Vero cells under various cell culture conditions, such as age of cells, seeding concentration, and time of harvest. None of these cell culture variables were found to affect virus titres.

Animals↗
PubMed2005

A randomised controlled trial of empowerment training for Chinese abused pregnant women in Hong Kong.

OBJECTIVE: To evaluate the effectiveness of an empowerment intervention in reducing intimate partner violence (IPV) and improving health status. DESIGN: Randomised controlled trial. SETTING: Antenatal clinic in a public hospital in Hong Kong. SAMPLE: One hundred and ten Chinese pregnant women with a history of abuse by their intimate partners. METHODS: Women were randomised to the experimental or control group. Experimental group women received empowerment training specially designed for Chinese abused pregnant women while the control group women received standard care for abused women. Data were collected at study entry and six weeks postnatal. MAIN OUTCOMES MEASURES: IPV [on the Conflict Tactics Scale (CTS)], health-related quality of life (SF-36) and postnatal depression [Edinburgh Postnatal Depression Scale (EPDS)]. RESULTS: Following the training, the experimental group had significantly higher physical functioning and had significantly improved role limitation due to physical problems and emotional problems. They also reported less psychological (but not sexual) abuse, minor (but not severe) physical violence and had significantly lower postnatal depression scores. However, they reported more bodily pain. CONCLUSION: An empowerment intervention specially designed for Chinese abused pregnant women was effective in reducing IPV and improving the health status of the women.

Adult↗
PubMed2004

Interspecific hybridization of Trifolium alexandrinum with T. constantinopolitanum using embryo rescue.

The embryo rescue technique was successfully used to raise hybrids between Trifolium alexandrinum and T. constantinopolitanum. As a result of its narrow genetic base, genetic improvement in Egyptian clover (syn. Berseem; T. alexandrinum), an important fodder crop in tropical and subtropical countries, is hampered, thereby making it imperative to introduce alien genes from related species. In a conventional interspecific hybridization program, hybrids could not be raised due to post-fertilization barriers. Of the several combinations tried, pollination 2 days after emasculation was found to be the best. Globular embryos were observed 5-7 days after pollination (DAP), followed by heart-shaped embryos 10-12 DAP. Embryos excised at the heart-shaped stage responded well to EC3 culture medium. Of 612 crosses, 33 healthy embryos could be excised and cultured on EC3 medium. The plumule emerged 8-12 days following inoculation. The embryo-rescued plants were hardened, inoculated with Rhizobium and transferred to the field. The hybrids showed intermediate morphological features with reduced pollen fertility (55-65%) and a chromosomal complement of 2n = 16. Biochemical characterization using isozymes confirmed hybridity.

Crosses, Genetic↗
PubMed2004

Novel methods of forming self-assembled nanostructured materials: Ni nanodots in Al2O3 and TiN matrices.

We have developed two novel methods of growing self-assembled nanodot arrays of uniform size (diameter 2-50 nm) of a variety of materials in crystalline as well as amorphous matrices. These methods employ a pulsed laser deposition technique and are classified as: (a) sequential growth method; and (b) simultaneous growth method. In the first method, the nanodots and matrix material are formed sequentially, while in the second method, nanodots and matrix materials grow simultaneously. In the sequential growth, self-assembly of nanodots is controlled by the flux of materials, interfacial energy, intervening matrix layer, substrate and laser parameters. For the simultaneous growth method of self-assembly of nanodots, there is additional requirement that the material of the nanodot and the matrix should be such that the Gibb's free energy of oxidation of the constituent of matrix material is much lower than that of the nanodot material.

Aluminum Oxide↗
PubMed2003

Carotid and femoral arterial wall mechanics in scleroderma.

OBJECTIVE: Large-vessel arterial disease is increasingly recognized as a major cause of morbidity in autoimmune rheumatic disorders. Recent evidence suggests that scleroderma (systemic sclerosis, SSc) may be linked to altered fibrillin-1 metabolism associated with a defect in chromosome 15q. If this is the case, we may expect to see changes in the arterial wall mechanics of large vessels not clinically involved in the disease process. We undertook a study to determine whether the biomechanical properties and intima-media thickness (IMT) of the elastic carotid artery and the muscular femoral artery are altered in subjects with limited (lcSSc) and diffuse (dcSSc) cutaneous SSc. METHODS: Measurements of carotid and femoral wall mechanics were made in 33 patients with lcSSc, 19 patients with dcSSc and 21 control subjects, using a duplex scanner coupled to a Wall Track system. Their age, gender, body mass index, heart rate, systolic and diastolic blood pressures, presumed cardiovascular load, and plasma creatinine, fasting cholesterol, triglyceride and glucose concentrations were also measured. RESULTS: There was a progressive and significant reduction (P < 0.001) in the elastic properties of the carotid artery from the control group (compliance, 16.24 +/- 4.39 %mmHg(-1) x 10(-2)) to the lcSSc group (10.89 +/- 2.43 %mmHg(-1) x 10(-2)) to the dcSSc group (7.65 +/- 2.08 %mmHg(-1) x 10(-2)), even after adjustment for the systemic physiological and biochemical variables studied, which are known to influence the mechanics of arterial walls. There was no apparent difference between the groups in the mean elastic indices of the femoral artery and the IMT of the carotid and femoral arteries. CONCLUSION: The elastic properties of the carotid artery are significantly altered in SSc, and the two major subsets of SSc may be distinguished by their carotid artery biomechanics. This suggests that connective tissue abnormality occurs at sites not previously assessed.

Carotid Arteries↗
PubMed2003

Magnetic beads (Dynabead) toxicity to endothelial cells at high bead concentration: implication for tissue engineering of vascular prosthesis.

Magnetic beads (Dynabeads) have been used for the purification of endothelial cells. One application for this procedure may be for single-stage seeding of bypass grafts. The number of endothelial cells (EC) isolated is crucial and therefore to increase the number of cells extracted, a higher number of Dynabeads per cell may need to be used. The effect of large numbers of CD31 Dynabeads on cell proliferation/metabolism is unknown. We undertook this study using CD31-coated Dynabeads and EC from human umbilical vein. EC were coated at concentrations of 4, 10, or 50 beads per cell. The cells were cultured for 6 days with control being normal EC. Cellular proliferation was assessed by trypsinization of cells and metabolism assessed with an Alamar blue viability assay. In a further experiment a compliant polyurethane graft was single-stage seeded with both coated Dynabeads and normal EC. The results showed that using a higher number of beads per cell resulted in a reduction in cell proliferation and a reduction in cell metabolism. The total number of Dynabeads-coated cells in culture compared to controls (%) by day 6 were 30.7 +/- 2.56, 41.3 +/- 9.8 and 59.2 +/- 7.3 for 50, 10, and 4 beads per cell, respectively. The corresponding results for Alamar blue were 43.7 +/- 1.2, 61.8 +/- 1.4, and 72.1 +/- 4.3. The seeded grafts showed reduced metabolism with the Dynabeads-coated EC. In conclusion, high numbers of beads per cell have a late detrimental effect on cell proliferation and metabolism. Therefore for single-stage seeding lower numbers of Dynabeads will need to be used with resultant reduction in the number of available EC.

Biocompatible Materials↗
PubMed2003

Extraction of cells for single-stage seeding of vascular-bypass grafts.

Experimental data are reported for the seeding of prosthetic vascular grafts with either mesothelial or endothelial cells as part of a research strategy in tissue engineering with the aim of improving graft patency and developing new techniques for single-stage cell extraction and seeding that would give a step reduction in surgery time. New data are reported for two different sources of cells, peritoneal lavage and subcutaneous fat. All experiments were undertaken in patients undergoing abdominal aortic aneurysm repair. Cells extracted from peritoneal lavage were insufficient for a single-stage seeding process. Subcutaneous fat was processed using either a positive cell-extraction method using CD31 Dynabeads or by a negative extraction method using CDw90-coated magnetic beads. Only positive cell extraction gave reliably sufficient numbers of endothelial cells as a source for single-stage seeding of vascular grafts.

Aged↗
PubMed2003

Improving the patency of vascular bypass grafts: the role of suture materials and surgical techniques on reducing anastomotic compliance mismatch.

BACKGROUND: compliance mismatch is an important factor in the development of myointimal hyperplasia in both coronary and vascular anastomoses. This mismatch may be reduced by the use of newer suture materials and techniques. This review discusses the current techniques and materials used to date in generating anastomoses in both coronary and vascular applications and to correlate these with the degree of inherent compliance achieved. METHODS: PubMed, ISIS, CAS and PAS database searches were performed. Other articles were cross-referenced. RESULTS AND CONCLUSION: continuous suture is still the most used technique in both cardiac and vascular surgery for the generation of anastomoses due to the reduced time and improved haemostasis. However, continuous suture results in a greater compliance mismatch than the interrupted technique. Vein cuffs and patches improve compliance and transmission of pulsatile blood flow and offer improvement of graft patency. Alternative to sutures are biological glue, clips and laser generated solders all of which have shown promising results, but further work is required before they become applicable for routine use.

Anastomosis, Surgical↗
PubMed2003

Differentiation of primary and secondary Raynaud's disease by carotid arterial stiffness.

INTRODUCTION: primary Raynaud's disease may be difficult to differentiate clinically from the secondary form with an underlying connective tissue, haematological, neurovascular or drug-induced disorder. We undertook a study to determine the elastic carotid and muscular femoral arterial biomechanical properties and intima-media thickness (IMT) in subjects with primary and secondary Raynaud's disease, to assess whether these parameters could differentiate the two conditions. METHODS: twenty patients with primary Raynaud's disease and 53 subjects with secondary Raynaud's associated with scleroderma (systemic sclerosis, SSc) had measurements of their carotid and femoral wall mechanics with a duplex scanner coupled to a Wall Track system. Their age, gender, body mass index, heart rate, systolic and diastolic blood pressures, presumed cardiovascular load, plasma creatinine, fasting cholesterol, triglyceride and glucose concentrations were also measured. RESULTS: the carotid elastic properties [mean (SD): elastic modulus: 560 (180) vs 1204 (558) mmHg,p <0.001 and stiffness index: 5.69 (1.35) vs 11.92 (6.4), p<0.001 for primary and secondary Raynaud's respectively] were significantly impaired in patients with secondary Raynaud's disease even after adjustment for potentially influencing physiological and biochemical variables. There were no statistical differences in the femoral elastic properties or the carotid and femoral IMTs between the two groups. CONCLUSION: Duplex determination of the carotid elasticity or stiffness is different in primary Raynaud's phenomenon compared with secondary Raynaud's associated with SSc. This may be a useful non-invasive tool, in addition to autoantibody markers and nail-fold capillaroscopy, to differentiate between the two forms of Raynaud's phenomenon.

Adult↗
PubMed2003

Improving endothelial cell retention for single stage seeding of prosthetic grafts: use of polymer sequences of arginine-glycine-aspartate.

OBJECTIVE: single stage seeding within the timeframe of a typical vascular operation has not been successful. One reason for this is poor cell adherence to the graft lumen once exposed to pulsatile blood flow. In this study we have carried out investigations with the use of two different fibronectin-based peptides, fibronectin-like engineered protein polymer (FEPP) which contains multiple copies of arginine-glycine-aspartate (RGD) and fibronectin adhesion promoting peptide (FAPP) to improve cell adherence. MATERIALS AND METHODS: FAPP and FEPP were coated onto native polyurethane and heparinised polyurethane grafts. The grafts were then seeded for either 1 or 2h with human umbilical vein endothelial cells (HUVEC). After the incubation period the cells were washed off and cell retention was calculated. Cell metabolism was measured using Alamar Blue, and confirmed with scanning electron microscopy (SEM). RESULTS: heparinised grafts coated with FEPP showed the best cell retention after both 1 and 2h seeding (80+/-4% vs 81+/-3%). This graft had no significant difference in cell retention after both times whilst all the other grafts had better cell retention after a 2h seeding. The Alamar blue and SEM results confirmed cell viability and function for all graft types. CONCLUSION: heparinised graft coated with FEPP allows significant cell retention after only 1h of seeding and shows promise for single stage seeding.

Blood Vessel Prosthesis↗