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Biomedical subjects

Ritu Agarwal

Publications and source records attributed to Ritu Agarwal.

8 recordsLinked to original sources
PubMed2006

Selective neck dissection (I-III) for node negative and node positive necks.

Selective neck dissection (I-III) for oral cancers offers similar regional control rates with less morbidity as compared with modified radical neck dissection. Charts of 414 patients with oral cancer, who underwent selective neck dissection (I-III) during 1994-2001, were analysed retrospectively. Seventy nine percent of the patients had a primary tumour in the gingivo-buccal complex. Cancer of tongue showed a trend towards higher regional failure (12.3%) as compared to gingivo-buccal cancers (6.5%). Primary tumour was staged as T1-8%, T2-47%, T3-19% and T4-26%. Sixty five percent of the patients were clinically node negative. Isolated neck failure was observed in 4.8% of patients at 2 years and in 5.8% at 5 years. De-differentiation of primary tumour and perineural spread were associated with regional failures. Eighty three percent of the neck recurrences were in the ipsilateral neck and only 16% of these were at levels IV or V. In all, 30% of all regional failures were outside the field of dissection.

Adult↗
PubMed2006

Bipaddle pectoralis major myocutaneous flap in reconstructing full thickness defects of cheek: a review of 47 cases.

We present a series of reconstruction of 47 patients with large full thickness cheek defects secondary to cancer ablative surgery. All patients were reconstructed primarily by bipaddle pectoralis major myocutaneous (PMMC) flap. The age of patients ranged from 25 to 85 years (mean 49.5 years). All patients were male. The size of the paddle used for mucosal defect repair ranged from 5 x 3 to 9 x 7 cm and the size of the paddle used for skin cover ranged from 4 x 4 to 9 x 8 cm. The total flap size ranged from 10 x 5 to 17 x 7 cm. One patient had complete loss of flap (2.12%). Sixteen patients had minor complications all of which settled with conservative management. The follow up period varied from 1 month to 4 years. The modification adopted in bipaddling the flap was based on anatomical location of perforators to ensure good blood supply to both paddles of flap. Placing the flap horizontally with inclusion of nipple and areola increased the reach and size of available flap. We found the technique to be anatomically sound, technically easy and reliable. Precautions taken included proper assessment of reach of the paddle, placing not more than one-third of the paddle outside the muscle and securing the skin paddle to the muscle to avoid shearing of perforators during flap raising. We conclude that this technique is a useful alternative where microsurgical free tissue transfer is not possible or as a salvage procedure in selected large full thickness oral cavity lesions. However, the disadvantages of this method include loss of nipple and areola and technical difficulty in obese patients and females.

Adult↗
PubMed2004

Cytosolic NADPH may regulate differences in basal Nox oxidase-derived superoxide generation in bovine coronary and pulmonary arteries.

Because systems controlled by basal NAD(P)H oxidase activity appear to contribute to differences in responses of endothelium-removed bovine coronary (BCA) and pulmonary (BPA) arteries to hypoxia, we characterized the Nox oxidases activities present in these vascular segments and how cytosolic NAD(P)H redox systems could be controlling oxidase activity. BPA generated approximately 60-80% more lucigenin (5 microM) chemiluminescence detectable superoxide than BCA. Apocynin (10 microM), a NAD(P)H oxidase inhibitor, and 6-aminonicotinamide (1 mM), a pentose phosphate inhibitor (PPP), both attenuated (approximately by 50-70%) superoxide detected in BPA and BCA. There was no significant difference in the expression of Nox2 or Nox4 mRNA or protein detected by Western blot analysis. NADPH and NADH increased superoxide in homogenates and isolated microsomal membrane fractions in a manner consistent with BPA and BCA having similar levels of oxidase activity. BPA had 4.2-fold higher levels of NADPH than BCA. The activity and protein levels of glucose-6-phosphate dehydrogenase (G6PD), the rate-limiting PPP enzyme generating cytosolic NADPH, were 1.5-fold higher in BPA than BCA. Thus BPA differ from BCA in that they have higher levels of G6PD activity, NADPH, and superoxide. Because both arteries have similar levels of Nox expression and activity, elevated levels of cytosolic NADPH may contribute to increased superoxide in BPA.

Acridines↗
PubMed2004

Managing team interpersonal processes through technology: a task-technology fit perspective.

This article addresses the broad question, How can virtual teams that manage a majority of their interactions through information and communication technologies (ICTs) be made more effective? Focusing specifically on interpersonal interactions, the task-technology fit paradigm is used as the foundation for a theoretical model that seeks to identify how such teams can match available communication technologies to the different types of interpersonal interactions in which they engage. The authors draw on media synchronicity theory to identify the functionalities of the wide range of ICTs available today, and map these functionalities onto the salient communication needs of 3 key interpersonal processes: (a) conflict management, (b) motivation and confidence building, and (c) affect management. The model also incorporates a temporal dimension examining how the communication needs, and hence, the need for ICT functionality, varies depending on the virtual team's developmental stage. Opportunities for future research arising from the theoretical model are discussed.

Conflict, Psychological↗
PubMed2003

Two distinct pathways for inhibiting pds1 ubiquitination in response to DNA damage.

The presence of DNA damage activates a conserved cellular response known as the DNA damage checkpoint pathway. This pathway induces a cell cycle arrest that persists until the damage is repaired. Consequently, the failure to arrest in response to DNA damage is associated with genomic instability. In budding yeast, activation of the DNA damage checkpoint pathway leads to a mitotic cell cycle arrest. Following the detection of DNA damage, the checkpoint signal is transduced via the Mec1 kinase, which in turn activates two kinases, Rad53 and Chk1 that act in parallel pathways to bring about the cell cycle arrest. The downstream target of Rad53 is unknown. The target of Chk1 is Pds1, an inhibitor of anaphase initiation whose degradation is a prerequisite for mitotic progression. Pds1 degradation is dependent on its ubiquitination by the anaphase-promoting complex/cyclosome ubiquitin ligase, acting in conjunction with the Cdc20 protein (APC/CCdc20). Previous studies showed that the Rad53 and Chk1 pathways independently lead to Pds1 stabilization but the mechanism for this was unknown. In the present study we show that both the Chk1 and the Rad53 pathways inhibit the APC/CCdc20-dependent ubiquitination of Pds1 but they affect different steps of the process: the Rad53 pathway inhibits the Pds1-Cdc20 interaction whereas Chk1-dependent phosphorylation of Pds1 inhibits the ubiquitination reaction itself. Finally, we show that once the DNA damage is repaired, Pds1 dephosphorylation is involved in the recovery from the checkpoint induced cell cycle arrest.

Cdc20 Proteins↗
PubMed2002

Phosphorylation of the mitotic regulator Pds1/securin by Cdc28 is required for efficient nuclear localization of Esp1/separase.

Sister chromatid separation at the metaphase-to-anaphase transition is induced by the proteolytic cleavage of one of the cohesin complex subunits. This process is mediated by a conserved protease called separase. Separase is associated with its inhibitor, securin, until the time of anaphase initiation, when securin is degraded in an anaphase-promoting complex/cyclosome (APC/C)-dependent manner. In budding yeast securin/Pds1 not only inhibits separase/Esp1, but also promotes its nuclear localization. The molecular mechanism and regulation of this nuclear targeting are presently unknown. Here we show that Pds1 is a substrate of the cyclin-dependent kinase Cdc28. Phosphorylation of Pds1 by Cdc28 is important for efficient binding of Pds1 to Esp1 and for promoting the nuclear localization of Esp1. Our results uncover a previously unknown mechanism for regulating the Pds1-Esp1 interaction and shed light on a novel role for Cdc28 in promoting the metaphase-to-anaphase transition in budding yeast.

Active Transport, Cell Nucleus↗
PubMedDate not supplied

Mitotic regulation: the fine tuning of separase activity.

Mitotic progression requires the dissolution of cohesion between sister chromatids. Cohesion is dissolved by an essential protease known as separase. Separase is highly conserved throughout evolution and is subjected to multiple levels of regulation. Here we discuss recent studies that unravel several key mechanisms for regulating separase activity.

Animals↗