Facile Synthesis of Hybrid Nanoflowers Using Glycine and Phenylalanine and Investigation of Their Catalytic Activity

In the context of the proposed work, two different amino acids (Glycine, Phenylalanine) have interacted with copper ions in a phosphate buffer (PBS) in place of enzymes. This interaction resulted in the nucleation of copper phosphate crystals and the formation of flower-shaped amino acid-copper hybrid nanostructures (AA-hNFs), which grew through self-assembly. While Cu (II) ions in the structure of AA-hNFs were used as Fenton's agent for the catalytic activity. SEM, energy dispersive X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy measurements were used to define the AA-hNFs′ characterisation. The peroxidase-like activities of AA-hNFs were investigated by UV/VIS spectrophotometer. Metal nanoparticles have peroxidase-like activity. A class of enzymes known as peroxidases is able to catalyze the conversion of hydrogen peroxide into hydroxyl radicals. These radicals also take part in electron transfers with substrates, which results in color during oxidation. When cupric oxide nanoparticles are added to the peroxidase substrate while H₂O₂ is present, a blue color product with a maximum absorbance at=652 nm can result, demonstrating the catalytic activity of a peroxidase. The morphology and composition of AA-hNFs were carefully characterized and the synthesized parameters were optimized systematically. Results showed that the nanoparticles were dispersed with an average diameter of 7–9 μm and indicated a uniform flower shape. The results of the investigation are anticipated to significantly advance a number of technical and scientific sectors.     

Maturational changes in responses of tissue and airway resistance to histamine

Dreshaj, Ismail A., Musa A. Haxhiu, Charles F. Potter, FatonH. Agani, and Richard J. Martin. Maturational changes in responsesof tissue and airway resistance to histamine. J. Appl.Physiol. 81(4): 1785-1791, 1996.We determinedhow postnatal maturation affects the relative contributions of airwaysand lung parenchyma to pulmonary resistance(RL) and whether there are developmental differences in their respective responses to constrictive agents. We studied open-chest ventilated anesthetized piglets of threeages: 2-4 days, 2-3 wk, and 10 wk.RL was partitioned into tissue(Rti) and airway (Raw) resistance by means of alveolar capsules underbaseline conditions and after intravenous histamine. Postnatalmaturation was associated with a progressive decline inRL, Rti, and Raw and with anincrease in the contribution of Rti toRL from 38 ± 8% at 2-4days to 72 ± 2% at both 2-3 and 10 wk. Histamine causedRL to increase at all ages. Whenpartitioned into Rti and Raw, the percent increase in Rti significantlyexceeded that of Raw at both 2-4 days and 2-3 wk. Incontrast, the percent increase in Raw significantly exceeded that ofRti at 10 wk. Administration of atropine before histamine in pigletsaged 10 wk reduced the response of Rti and Raw to histamine.Histamine-induced responses ofRL were blocked by priorH₁-receptor blockade withpyrilamine (2 mg/kg). These results indicate that1) the contribution of Rti and Rawto RL changes during maturationand that 2) contractile responses toexogenous histamine are manifest predominantly in most distal airwaysand lung parenchyma during early postnatal life; with advancingmaturation there is greater contribution of airways to the increase inRL induced by histamine.

     

Human immunodeficiency virus type 2 (HIV-2) seroprevalence and characterization of a distinct HIV-2 genetic subtype from the natural range of simian immunodeficiency virus-infected sooty mangabeys.

The extent of zoonotic infections in rural Sierra Leone, where both feral and pet sooty mangabeys harbor divergent members of the human immunodeficiency virus type 2 (HIV-2)-sooty mangabey simian immunodeficiency virus (SIVsm) family, was tested in blood samples collected from 9,309 human subjects in 1993. Using HIV-1- and HIV-2-specific enzyme immunoassays and confirmatory Western blot analysis to test for antibodies to SIVsm-related lentiviruses, we found only nine subjects (0.096%) who tested positive for HIV: seven tested positive for HIV-1 and two tested positive for HIV-2. Compared with other rural West African communities, Sierra Leone displayed the lowest seroprevalence (0.021%) of HIV-2 infection yet reported, much lower than the previously reported seroprevalence in SIVsm-infected feral and household pet sooty mangabeys. Heteroduplex analysis demonstrated that two of the newly found HIV-1 strains belonged to subtype A, the most common HIV-1 subtype in Africa, but this is the first report of subtype A in Sierra Leone. The two HIV-2-infected individuals harbored two distinct HIV-2 strains, designated 93SL1 and 93SL2. Phylogenetic analysis indicated that HIV-2 93SL1 is a member of HIV-2 subtype A, the first strain of this HIV-2 subtype found in Sierra Leone. In contrast, HIV-2 93SL2 belongs to none of the five previously characterized HIV-2 subtypes (A to E) but is a new subtype, herein designated F, having the most divergent transmembrane sequences yet reported for HIV-2. The fact that both of the two most divergent HIV-2 subtypes known, E and F, are rare and found as single occurrences in persons from Sierra Leone may be related to the fact that this small region of West Africa also contains free-living and household pet sooty mangabeys with highly divergent variants of SIVsm. This finding provides support for the hypotheses that new HIV-2 subtypes result from independent cross-species transmission of SIVsm to the human population and that these single-occurrence transmission events had not spread widely into the population by 1993.     

Identification,characterization, and developmental profile of a high molecular weight,juvenile hormone-binding protein in the hemolymph of the migratory grasshopper,Melanoplus sanguinipes

In the hemolymph of Melanoplus sanguinipes, a high molecular weight juvenile hormone binding protein (JHBP) was identified by photoaffinity labelling and found to have a M_r of 480,000. The JHBP, purified using native gel electrophoresis followed by electroelution, has an equilibrium dissociation constant for JH III of 2.1 nM and preferentially binds JH III over JH I. Antibody raised against JHBP recognized only the 480,000 band. Under denaturing conditions the native JHBP gave a single band with a M_r 78,000. The antibody against native JHBP recognized only the 78,000 protein in SDS-treated hemolymph samples, indicating that JHBP is a hexamer in this species. The concentration of JHBP fluctuates in both the sexes during nymphal and adult development in parallel with total protein content of hemolymph. © 1995 Wiley-Liss, Inc.     

Physiology and characterization of a fungal milk-clotting enzyme from Aspergillus flavus.

Aspergillus flavus produced extracellularly an active rennin-like enzyme when grown aerobically in whey media. The enzyme was detected at early stages of growth reaching a maximum after three to four days at 25 degrees. The activity was destroyed by heating to temperatures higher than 50 degrees, whereas the presence of skim milk during heating preserved the enzyme activity, at least, up to 70 degrees. Calcium chloride significantly stimulated the milk-clotting activity up to 1% final concentration. The clotting time was inversely proportional to protein concentration in the range 0.2-0.6 mg/ml and the enzyme exhibited marked stability when stored at 37 degrees at pH 6.     

The use of Opalina sudafricana in a biological test for diagnosing disordered metabolism of tryptophan in human subjects

Injections of urine of patients with bladder cancer linked with bilharziasis, simple urinary bilharziasis, ascariasis or ancylostomiasis, induced cyst formation found in Opalina sudafricana when injected into its host Bufo regularis. It is suggested that the carcinogenic tryptophan metabolites present in the injected urine reach the parasites in the recta of the experimental toads and stimulate them to divide mitotically to form small forms which eventually encyst. This test may be of a diagnostic help in detecting any abnormality in tryptophan metabolism in some human patients.     

Kinetic studies on the diaqua form of cis-platin and various nucleobases

Kinetic studies on cis-[Pt(NH3)2(OH2)2]2+ and various nucleobases show that this ion reacts more quickly with guanosine than with adenosine, cytidine, and thymidine, and that a monophosphoric acid unit considerably enhances the rate of reaction of guanosine; the kinetic preference of 5'-GMP over 5'-AMP may point to a greater thermodynamic selectivity.     

Cytological lesions in the midgut of Tribolium confusum larvae exposed to gamma radiation

The major cytological lesions in Tribolium confusum after irradiation were displayed by the midgut epithelium. At 24 hr following exposure to 5.3 kR, the regenerative cells called nidi appeared numerous. They gradually disappeared with increases in dosage and time in accordance with Arndt-Schulze's Law. The columnar epithelial cells and their nuclei appeared swollen and vacuolated on the fifth and twelfth day following exposure to 5.3 kR. They appeared disorganized and shed into the lumen of the midgut on the twelfth and fifth day following 50- and 70-kR irradiation, respectively. The basement membrane and the muscularis appeared loose on the fifth and twelfth day following 70-kR irradiation. It was observed that once the catabolic activity, i.e., histolysis, was initiated in the midgut, it continued to accelerate with increasing dose and time. Thus, the late effects at low doses, 5.3 and 10 kR, appeared as immediate effects at high doses, 50 and 70 kR. The differentiated cells, i.e., columnar epithelial cells, appeared radioresistant as compared to undifferentiated cells, i.e., regenerative cells, which appeared radiosensitive in accordance with the principle of Bergonie and Tribondeau.     

Effect of design dark fraction on the loss of biomass productivities in photobioreactors

Bioprocess and Biosystems Engineering - Design dark fraction reflects the unlit part of a microalgal culture system, as for example a hydraulic loop used for temperature or pH regulation, or a...