Biomedical subjects

Poonam Verma

Publications and source records attributed to Poonam Verma.

5 recordsLinked to original sources

PubMed2007

Fabrication of agar-gelatin hybrid scaffolds using a novel entrapment method for in vitro tissue engineering applications.

Scaffolds of agar and gelatin were developed using a novel entrapment method where agar and gelatin molecules mutually entrapped one another forming stable cell adhesive matrices. Glutaraldehyde was used as a crosslinking agent for gelatin. Three types of hybrid matrices were prepared using agar and gelatin in different proportions in the weight ratio of 1:1, 2:1, and 3:1. Surface characterization of dry scaffolds was carried out by scanning electron microscope. Swelling studies were carried out in phosphate buffer saline (PBS) at physiological pH 7.4. The integral stability of the scaffolds was evaluated by estimating the released disintegrated gelatin from them in PBS at pH 7.4. The attachment kinetics of the cells was evaluated by culturing mouse fibroblast cell line NIH 3T3 on films. The cytocompatibility of these matrices was determined by studying growth kinetics of NIH 3T3 cells on them and morphology of cells was observed through optical photographs taken at various days of culture. It was found that the matrices containing agar and gelatin in 2:1 weight ratio exhibited best growth kinetics. The results obtained from these studies have suggested that the above-described method is a cheap and easy way to fabricate agar-gelatin hybrid scaffolds to grow cells which can be used in various in vitro tissue engineering applications like screening of drugs.

Agar↗

PubMed2005

Axonal protein synthesis and degradation are necessary for efficient growth cone regeneration.

Axonal regeneration can occur within hours of injury, the first step being the formation of a new growth cone. For sensory and retinal axons, regenerative ability in vivo correlates with the potential to form a new growth cone after axotomy in vitro. We show that this ability to regenerate a new growth cone depends on local protein synthesis and degradation within the axon. Axotomy in vitro leads to a fourfold to sixfold increase in 3H-leucine incorporation in both neurones and axons, starting within 10 min and peaking 1 h after axotomy. Application of protein synthesis inhibitors (cycloheximide and anisomycin) to cut axons, including axons whose cell bodies were removed, or proteasome inhibitors (lactacystin and N-acetyl-Nor-Leu-Leu-Al) all result in a reduction in the proportion of transected axons able to reform growth cones. Similar inhibition of growth cone formation was observed on addition of target of rapamycin (TOR), p38 MAPK (mitogen-activated protein kinase), and caspase-3 inhibitors. Comparing retinal and sensory axons of different developmental stages, levels of ribosomal protein P0 and phosphorylated translation initiation factor are high in sensory axons, lower in embryonic axons, and absent in adult retinal axons. Conditioning lesions, which increase the regenerative ability of sensory axons, lead to increases in intra-axonal protein synthetic and degradative machinery both in vitro and in vivo. Collectively, these findings suggest that local protein synthesis and degradation, controlled by various TOR-, p38 MAPK-, and caspase-dependent pathways, underlie growth cone initiation after axotomy.

Aging↗

PubMed2005

Spinal cord regeneration.

Repairing the damaged spinal cord has for a long time eluded neuroscientists. Few other achievements in neuroscience would have such a tremendous impact amongst the medical profession and the public. Despite numerous efforts, no patient has yet benefited from a regeneration therapy. Recent advances in the basic science of axon regeneration have opened new doors of hope towards prevention and cure of the devastating effects of spinal cord injury (SCI), and treatments that could encourage a partial repair of spinal injury are imminent. This article reviews the impact of SCI on patients, the current reparative strategies being explored and their potential clinical applications.

Cell Transplantation↗

PubMed2005

The ability of axons to regenerate their growth cones depends on axonal type and age, and is regulated by calcium, cAMP and ERK.

The processes activated at the time of axotomy and leading to the formation of a new growth cone are the first step in regeneration, but are still poorly characterized. We investigated this event in an in vitro model of axotomy performed on dorsal root ganglia and retinal explants. We observed that the dorsal root ganglion axons and retinal ganglion cell axons, which had grown out on a poly d-lysine/laminin substrate at the time of culture preparation greatly differed in their regenerative response after a subsequent in vitro lesion made far from the cell body. The majority of axons of adult dorsal root ganglia but only a small percentage of axons of adult retinal ganglion cells regenerated new growth cones within four hours after in vitro axotomy, though both kinds of axons were growing before the lesion. The depletion of extracellular calcium and the inhibition of extracellular-signal regulated kinase 1,2 (ERK) and protein kinase A (PKA) at the time of injury significantly impaired the capacity of dorsal root ganglia axons to re-initiate growth cones without affecting growth cone motility. Pharmacological treatments directed at increasing the level of cAMP promoted growth cone regeneration in adult retinal ganglion cell axons in spite of the low regenerative potential exhibited in normal conditions. Understanding the cellular mechanisms activated at the time of lesion and leading to the formation of a new growth cone is necessary for devising treatments aimed at enhancing the regenerative response of injured axons.

Actins↗

PubMedDate not supplied

Malaria genome project and its impact on the disease.

Malaria remains uncontrolled to-date due to lack of effective parasite and vector control strategies. With the completion of the host, parasite and vector genome projects more suitable and effective disease control measures can be achieved. Here we have reviewed the Plasmodium falciparum genome project and its impact on malaria research in future. The parasite genome project has revealed certain metabolic pathways which can be targeted to develop antimalarial drugs. It has also identified large number of potential antigens for the future potential vaccines. Now the researchers in the malaria field can plan to take up the studies, which can yield more fruitful results within the limited financial resources using bioinformatics, proteomics, structural, functional and comparative genomics, etc.

Animals↗