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Biomedical subjects

G P Agarwal

Publications and source records attributed to G P Agarwal.

At least 19 recordsLinked to original sources
PubMed2003

Optimization of immobilized metal ion affinity chromatography for single-step purification of recombinant ovine growth hormone expressed in Escherichia coli.

In the present investigation, Sepharose 6B gel with 1,4-butanediol diglycidyl ether as spacer arm, iminodiacetic acid as the ligand and Cu2+, Ni2+ as metal ions were used to prepare an immobilized metal ion affinity (IMA) gel. The binding capacities of recombinant ovine growth hormone (roGH) onto IMA gels were maximized in the packed bed column. Parameters influencing the purification efficiencies such as pH, ionic strength and flow-rate were optimized to achieve improved separation. The roGH was purified from inclusion bodies with an overall yield of 73.5% and purity of 94.3% using a Cu(2+)-iminodiacetic acid (IDA) column. However, the Ni(2+)-IDA column was more successful in purifying the roGH from crude cell lysate in a single-step with a yield of 83% and purity of 92.5%.

Animals↗
PubMed2001

Interactions of proteins with immobilized metal ions: a comparative analysis using various isotherm models.

Immobilized metal ion affinity chromatography (IMAC) is now a widely accepted technique for the purification of natural and recombinant therapeutic products and is beginning to find industrial applications. The design, optimization, and scale-up of a chromatographic process using IMAC demands a thorough understanding to be developed regarding the fundamental factors governing the various interactions between immobilized metal ions and proteins. Consequently, there is an immediate need to find out a theory that is able to account for these interactions most efficiently in a qualitative as well as a quantitative manner. In view of this requirement, the interactions of several model proteins (lysozyme, ovalbumin, bovine serum albumin, conalbumin, and wheat germ agglutinin) with metal (Cu(II), Ni(II))-chelated IDA (iminodiacetate) and tris(2-aminoethyl)amine were investigated. The adsorption data were analyzed using four isotherm models, viz., the general affinity interaction theory/Langmuir model, the Freundlich model, the Temkin model, and the Langmuir-Freundlich model, and the sorption parameters were computed. Although the first three models were applicable to some protein-IMA-M(II) systems, the Langmuir-Freundlich model appeared to be the most efficient model for explaining the interactions of proteins with IMA-M(II) gels. Also, this model was able to explain cooperativity and binding heterogeneity in quantitative terms. It is envisaged that this analysis would be useful in developing an improved understanding of protein-immobilized metal ion interactions and providing guidelines for designing preparative-scale separations using IMAC.

Cations↗
PubMed2000

Bovine serum albumin-hemoglobin fractionation: significance of ultrafiltration system and feed solution characteristics.

This work investigates the fractionation of similar molecular weight proteins bovine serum albumin (69 kD) and bovine hemoglobin (67 kD) by ultrafiltration. Three different membranes, viz. regenerated cellulose, poly(sulfone) and surface modified poly(acrylonitrile), each with a nominal molecular cutoff rating of 100 kD, were examined. The experiments were conducted in dead end, crossflow and vortex flow filtration modes and the separation was studied as a function of feed pH and ionic strength. Under similar system hydrodynamics, the surface modified poly(acrylonitrile) membrane displayed the highest resolution with minimum membrane fouling. The separation could be improved further by operating at low applied pressure (40 kPa) and high mass transfer (> 20 x 10(-6) m/s) in a vortex flow module. Under these conditions, the highest separation factor of 40 was obtained at the pI of hemoglobin.

Filtration↗
PubMed1994

Prevalence of ectoparasites on goats in Dehradun (India).

The prevalence of two phthirapteran species, Bovicola caprae and Linognathus africanus, on 1048 goats from Dehradun (India) was 79.2% and 38% respectively. Prevalence of both species was higher on visibly weaker and less hairy goats. Sex related differences in prevalence were not found. The prevalence of L. africanus was slightly higher on young goats but the same was not true in case of B. caprae. The incidence of B. caprae showed moderately negative correlation with environmental temperature and photoperiod. The relative intensity of B. caprae has been found higher during winter months, followed by summers. Study primarily deals with lice but the information about prevalence of other ectoparasites like ticks, fleas and keds, has also been supplemented.

Age Distribution↗
PubMed1994

Population structure of goat biting louse Bovicola caprae (Phthiraptera: Ischnocera).

The population structure of Bovicola caprae on goats has been recorded by examining 57 goatskins (45 by brushing cum searching and 12 by dissolving method). Population composition, sex ratio, adult nymph ratio has been recorded at different levels of infestation. The female dominated over the male population and male: female has been found to be 1:2 by brushing cum searching and 1:1.7 by dissolving method. Likewise, A:N was found to be 1:1.2 by brushing cum searching and 1:17 by dissolving method. The number of males and females follow similar pattern throughout population and were found to exhibit a high degree of correlation.

Animals↗
PubMed1989

Distribution of Mallophaga on the body of Acridotheres tristis (Aves).

4 species of Mallophaga (2 Amblycera, Menacanthus eurysternus and Myrsidea sp., and 2 Ischnocera, Brueelia chayanh and Sturnidoecus affinis) coexist on the body of Common Myna, Acridotheres tristis. The distribution of eggs, nymphs and adults of these species on the body of host is discussed. The patterns of distribution coincides with their morphological adaptations.

Animals↗
PubMed1988

Seasonal changes in the population of Mallophaga on Acridotheres tristis.

83.41% specimens of Common Myna were found infested with one to four species of Mallophaga, during the year 1984. Incidence of infestation and the indices were higher during the summer months and lower during winter months. The reasons of seasonal abundance are also discussed. Temperature seems to be one of the factors. The seasonal changes in population were found corresponding to the gonadal cycle of the host.

Animals↗
PubMed1983

Antigenic relationship between downy and granular forms of Trichophyton mentagrophytes and Trichophyton rubrum.

One strain each of granular and downy varieties of Trichophyton mentagrophytes and two strains each of granular and floccose colonial types Trichophyton rubrum were used for preparation of antigens. The antigens were analyzed by double diffusion against homologous and heterologous antisera raised in rabbits. A total of 17 distinct antigens were recognized, seven of which were common to two dermatophytes. Granular and downy varieties of the Trichophyton species produced on additional line of nonidentity. Cross reactions failed to establish any relationship between similar morphologic forms of different dermatophytes. One isolate of T. rubrum, which was originally the floccose culture type but changed into the granular form after artificial infection, showed an antigenic relationship to the floccose culture.

Antigens, Fungal↗
PubMed1983

Review article: in vitro rearing of Mallophaga.

From time to time, a number of attempts have been made by various workers to rear the mallophagan species in vitro. Some of the species have been successfully reared while some of them could be reared for shorter periods but others could not be reared at all. This may be on account of diverse temperature, humidity and nutritional requirements of various species. In the present article an attempt has been made to review the work done for in vitro rearing of Mallophaga. The different aspects like the temperature, humidity, nutritional requirements of mallophagan species, the methodology used by different workers, the optimum conditions for better rearing of mallophagan species and also some of the practical difficulties involved for their rearing, survival, egg laying, morphogenesis and hatching have been discussed.

Animals↗
PubMed1983

Retrocerebral endocrine complex of a phthirapteran parasite, Laemobothrion percnopteri (Mallophaga: Amblycera), infesting Indian scavanger vulture.

The retrocerebral endocrine complex of Laemobothrion percnopteri Gervais (Phthiraptera: Amblycera) has been described. The neurosecretory cells occur, only in the pars intercerebralis of the brain, in 2 groups of 3 cells each, each group being situated dorsally on the 2 sides of the median line. The perikaryons of nervi corporis cardiac I (NCC I) and their intra-ganglionic pathways are reported. The origin of nervi corporis cardiaci II (NCC II) could not be directly traced. Corpora allata also contain the neurosecretory material. There is no apparent connection between the neurosecretory cells and the aorta. This is the first report of the presence of neurosecretory cells, the neurosecretory material and their pathways in Mallophaga.

Animals↗
PubMed1983

Haematophagous behaviour of Menacanthus eurysternus (Mallophaga, Amblycera).

Haematophagous nature of some mallophagan species is of great concern to the scientists working in the field. Such species cause harm to the host directly by reducing vitality and productivity and indirectly by acting as reservoir and transmitter of pathogenic strains of infectious diseases. Menacanthus eurysternus infesting common myna Acridotheres tristis feeds exclusively on host blood obtained by piercing the quill of pin feathers and by gnawing through the epidermis. As much as 88.56% adults, 73.91% third instar nymphs, 66.66% second instar nymphs and 83.21% first instar nymphs were found feeding on the host blood, when examined microscopically. This mallophagan species does not harbour any triturating agent and is not involved in cannibalism or predation.

Animals↗
PubMed1982

Effect of different temperatures and humidities on the development of the eggs of poultry louse, Lipeurus lawrensis tropicalis. (Phthiraptera: Ischnocera).

The temperature and humidity requirements for the development of the eggs of the poultry louse, Lipeurus lawrensis tropicalis were determined. It was found that temperature and humidity requirements for morphogenesis and hatching are not the same. Morphogenesis in the eggs of this louse takes place within a temperature range of 30-40 degrees C, the optimum range being 32-37 degrees C. Relative humidity does not seem to have any apparent effect on morphogenesis.

Animals↗
PubMed1982

Vagina of Lipeurus lawrensis tropicalis, an ischnoceran Phthiraptera.

The vagina in poultry lice, Lipeurus lawrensis tropicalis PETERS, is a simple cup-shaped structure but is complex in its internal organization. It is divisible into anterior, central and posterior part. The anterior tubular part is deeply sunk into the posterior cup-shaped one due to the invagination of the central part. The space thus formed probably serves as sperm storage, as the spermatheca is absent.

Animals↗