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Articles by S. Ahmad
Total Records ( 11 ) for S. Ahmad
  J.Z. Khawaja , K. Naeem , Z. Ahmed and S. Ahmad
  Influenza is a highly contagious acute respiratory disease of avian origin that has caused epidemics and pandemics in humans for centuries. Among these avian influenza viruses (AIV), only serotypes H5 and H7 are considered highly pathogenic in poultry. However, serotype H9N2 has also been found to produce severe respiratory and reproductive tract infections in chickens. The previous studies have suggested that movement of poultry and wild birds play a major role in the spread of influenza viruses to distant areas in a country. The present study was carried out to monitor the prevalence of AIV in wild birds in certain areas of the Pakistan, which were free from infection during the outbreak of November 2003. In this regard, 7 wild bird species were selected and their blood, cloacal swabs and tissue samples were collected both for serological evaluation and virus isolation. The results indicated that antibodies to AIV serotype H9N2 were present in 10% of wild birds, whereas the virus was itself isolated only from 6.72% of the samples. These data provide the evidence regarding the wild birds as one of the major carrier of the AIV infection.
  M.M. Rahman , M.N. Amin and S. Ahmad
  Shoot tip and nodal segments from the field grown mature plants of native-olive (Elaeocarpus robustus Roxb.) were used as explants and were cultured on half strength of MS medium supplemented with different types of growth regulators either alone or in combinations. Among the growth regulators and supplements (BA, Kn, NAA and coconut water) that were used in the proliferation medium the best result was observed on 2 MS medium supplemented with 0.5 mgl G 1 BA + 0.5 mgl G 1 Kn + 0.1 mgl G 1 NAA + 15% CW, which promoted multiple shoot bud formation and sufficient shoot elongation. The well-developed shoots were excised to 3-4 cm cuttings and implanted individually on root induction medium. Highest percentage of micro cuttings showed root formation when they were cultured on 2 MS medium containing 0.2 mgl G 1 IBA and incubated under 30° C in dark for initial one week. The in vitro regenerated plants were successfully established in pot holes containing coco-peat on plastic tray and maintained under polythene tents. Survival of the plantlets under ex vitro condition was 60%.
  M.M. Rahman , M.N. Amin , S. Ahmad and R. Ahmed
  Micropropagation of native-olive (Elaeocarpus robustus Roxb.) has been proved difficult due very slow rooting of the shoot cuttings. The objective of the present investigation was to develop a technique for in vitro fast rooting of the aseptically grown shoots of native-olive. Rooting experiment was conducted on 1/2MS medium with various concentrations and combinations of NAA, IBA and IAA along with or without incubation at higher temperature (30 ° C) in dark condition for initial one week. Root forming performance of IBA was proved to be the best among the three auxins tested. Highest frequency of rooting with maximum number of effective roots was observed on the hormone-free medium in normal growth room condition after treating the microcutting with 0.2 mg L-1 IBA and incubated under 30 ± C in dark for initial one week. Early emergence and fast growth of roots without any malformation were also observed at the same treatment. At this culture condition 85% of the microcuttings produced 5.80 ± 0.15 roots per cutting where average length of roots per cutting was 4.65 ± 0.18 cm. The plantlets originated through the above treatment established themselves under ex vitro condition much quicker than those originated through other treatments.
  S.A. Saeed , H. Rasheed , T.M. Ali , Y. Qazi , S. Kabraji , L. Paul , R. Khan , F.A. Hussain and S. Ahmad
  This study was conducted to investigate the effects of nimesulide in platelet aggregation. It shows that nimesulide (1-100 μ M) inhibited platelets aggregation induced by adrenaline, (20-200 μ M). It also inhibed thromboxane A2 (TXA2) formation by platelets at low concentration (IC50; 1 μ M). However, much lower concentrations of nimesulide (0.01-0.1 μ M) potentiated the aggregatory response of subthreshold concentrations of adrenaline (0.2-2 μ M). Such an effect was blocked by Ca2+-channel blockers, verapamil and diltiazem (IC50: 7 and 46 μ M, respectively), nitric oxide donor, SNAP (IC50: 2 μ M) and cinchonine (10 nM) but not by genistein (up to 10 μ M). These results are indicative of the concentration-dependent dual effects of nimesulide on human platelet aggregation. The synergistic effect of low doses of nimesulide and adrenaline seems to be mediated through inhibition of multiple signaling pathways.
  M.M. Rahman , M.N. Amin , T. Ahamed , S. Ahmad , A. Habib , R. Ahmed , M.B. Ahmed and M.R. Ali
  An efficient protocol has been established for rapid production of plantlets using rhizome tip and lateral bud explants of the field grown plant. The explants were cultured on MS medium with auxins (NAA, IBA and IAA) and cytokinins (BA and Kn). Cent percent of the explants produced two or three shoot buds in each culture when they were cultured on MS medium containing 1.0 mg L -1 BA+0.1 mg L -1 NAA within three weeks of culture. The number of shoots per culture increased gradually when the primary cultures were subcultured in two weeks intervals. Highest number of 20.50±1.80 shoots proliferated in each culture when the explants of initially sprouted shoots were subcultured at three times on the same medium. Microshoots were isolated from the in vitro proliferated cluster of shoots produced roots in 100% cases on modified (MMS2) medium supplemented with 0.2 mg L -1 of IBA. Maximum number of 12.4±1.23 roots per microshoot were recorded on the medium containing 0.2 mg L -1 IBA. The regenerated plantlets were acclimatized and established on the soil with eighty five percent success.
  Yaseen M. , S. Ahmad and T. Hussain
  Wheat genotypes grown at control and adequate P levels differed markedly in their growth response. Growth response in terms of straw and grain yields was influenced by P application, genotype and their interaction. Relative reduction in grain yield ranged from none to 4%. Among all the genotypes Pervaz-94 showed response to P application. It was also observed that genotypes with high P concentration had low P uptake, low phosphorus use efficiency and hence low grain yield. Inqlab-91 and Chakwal-86 used phosphorus efficiently at both the P levels. Phosphorus efficient genotypes could be grown under low or little P fertilizer conditions.
  S. Ahmad , C.A. Call and E.W. Schupp
  Experiments were conducted in a representative Cymbopogon-Chrysopogon grassland in upland Balochistan to determine how seed (spikelet) attributes and seed (spikelet) dispersal mechanisms influence the regeneration of Cymbopogon jwarancusa and Chrysopogon aucheri. Cymbopogon jwarancusa had more filled and viable caryopses than Chrysopogon aucheri. Spikelets of both species have similar morphological features. Spikelet dispersal occurs primarily by wind over a 2 to 3-week period in late-June/early-July. Chrysopogon aucheri has one dispersal unit, a triplet spikelet. Cymbopogon jwarancusa has four different dispersal units: a paired spikelet, a partial raceme, an entire raceme, and a partial inflorescence (two racemes). Mean dispersal distances of spikelets from the perimeter of the basal crown of Cymbopogon jwarancusa and Chrysopogon aucheri plants were 94 and 79 cm, respectively. Spikelets were distributed in all directions around parent plants; however, the mean angle of dispersal for both species was toward the northeast, according to the prevailing wind direction. Spikelets of Cymbopogon jwarancusa and Chrysopogon aucheri moved mean distances of 26 and 32 cm, respectively, from all locations on the ground surface before becoming trapped in a microhabitat. Gravel interspaces and areas beneath plant canopies were the most common microhabitats, and captured the majority of spikelets of both species.
  S. Ahmad , C.A. Call and E.W. Schupp
  Not Available
  S. Ahmad , C.A. Call , E.W. Schupp and E.W. Schupp
  A number of seven microhabitats evaluated for seeding establishment were: under the canopy of Chrysopogon aucheri plants, under the canopy of Chrysopogon jwarancusa plants, within dead centers of Cymbopogon sucheri plantws, within dead centers of Cymbopogon jwarancuse plants, under the canopy of Artemisia maritima plants, gravel interspaces between plants, and soil interspaces between plants. Seeding emergence and establishment were evaluated under the natural precipitation regime of the 1997 growing season and a simulated, above-normal precipitation regime. Soil moisture and soil temperature data were recorded during the entire growing season. Above-normal precipitation increased the density of emerged seedlings for both species in all microhabitats. Cymbopogon jwarancusa had higher seedling densities than Chyrsopogon aucheri. Monsoon rains in late July 1997 enhanced emergence of both species from recently disappeared seeds. Seedling of both species emerged after monsoon rains but did not survive to the end of the growing season. Gravel interspaces were suitable microhabitats for seedling development, possibly due to the vertical entrapment of dispersal units and reduced competition from more distant, established plants. Above-normal precipitation did not have a significant effect on tiller development for either species. Cymbopogon jwarancusa seedling developed more tillers per plant than Vhyrysopogon aucheri seedlings.
  S. Saeed , S.A. Rasool , S. Ahmad and S.A Ali
  Staphylococcin Bac188, a bacteriocin/Bacteriocin-like Inhibitory Substance (BLIS) from Staphylococcus aureus AB188 was studied for its immunological and toxicological effects on experimental animals. The antigenicity/immunogenicity of staphylococcin Bac188 was determined by Ouchterlony technique and Enzyme Linked Immunosorbent Assay (ELISA). Accordingly, staphylococcin Bac188 is antigenically poor (in rabbit immune system) as the antibody titer was not found to be significant in Ouchterlony test. However, some immunogenicity was witnessed in ELISA, suggesting that low level of antigen-antibody reaction has occurred. The acute and chronic toxic studies with Bac188 do not show any toxic effects in diseases virgin (domestic rabbits) when injected with different regimen of doses (20, 40, 60 and 80 μg mL-1). Hematological studies with staphylococcin Bac188 showed that except for marginal increase in lymphocyte count in the test animal groups, no other significant effect was observed as compared to the control (rabbits injected with plain sterile saline). Further, different doses of staphylococcin Bac188 showed no significant biochemical changes in the normal profile of rabbit blood biochemistry.
  M. Aslam , S. Ahmad , I.A. Mahmood and T. Sultan
  Groundnut variety BARD-699 produced significantly the most promising yield than that of variety BARI-89 at Attock, Fatehjang and NARC, Islamabad. Rhizobium strains, NC-92 was found to be less efficient as compared to TAL-1000; TAL-1371. Nodule dry mass and number of pods per plant were much higher than that of control treatment. Although a significant difference in growth and yield of both the varieties due to Rhizobium inoculation was observed but on average basis TAL-1000 and TAL-1371 gave significantly better response for both the varieties in improving growth and yield at all sites. Nevertheless, future prospects for groundnut production are good in Pakistan if the farmers are realized to practice inoculation technology in their fields.
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