Comparative analysis of neonatal and adult rat carotid body responses to chronic intermittent hypoxia.

Previous studies suggest that carotid body responses to long-term changes in environmental oxygen differ between neonates and adults. In the present study we tested the hypothesis that the effects of chronic intermittent hypoxia (CIH) on the carotid body differ between neonates and adult rats. Experiments were performed on neonatal (1-10 days) and adult (6-8 wk) males exposed either to CIH (9 episodes/h; 8 h/day) or to normoxia. Sensory activity was recorded from ex vivo carotid bodies. CIH augmented the hypoxic sensory response (HSR) in both groups. The magnitude of CIH-evoked hypoxic sensitization was significantly greater in neonates than in adults. Seventy-two episodes of CIH were sufficient to evoke hypoxic sensitization in neonates, whereas as many as 720 CIH episodes were required in adults, suggesting that neonatal carotid bodies are more sensitive to CIH than adult carotid bodies. CIH-induced hypoxic sensitization was reversed in adult rats after reexposure to 10 days of normoxia, whereas the effects of neonatal CIH persisted into adult life (2 mo). Acute intermittent hypoxia (IH) evoked sensory long-term facilitation of the carotid body activity (sensory LTF, i.e., increased baseline neural activity following acute IH) in CIH-exposed adults but not in neonates. The effects of CIH were associated with hyperplasia of glomus cells in neonatal but not in adult carotid bodies. These observations demonstrate that responses to CIH differ between neonates and adults with regard to the magnitude of sensitization of HSR, susceptibility to CIH, induction of sensory LTF, reversibility of the responses, and morphological remodeling of the chemoreceptor tissue.     

Incidence of Keratinophilic Fungi from the Selected Soils of Kaziranga National Park,Assam (India)

Seventy-eight soil samples were collected from the various locations in the vicinity of Kaziranga National Park (Assam), India, during April to October 2009 and screened for the presence of keratinophilic fungi using the hair baiting techniques for isolation. Thirty-nine isolates were recovered and identified by recognition of their macro- and micromorphological features. Their identification was also confirmed by the BLAST search of sequences of the ITS1-5.8S-ITS2 rDNA region against the NCBI/GenBank data and compared with deposited sequences for identification purpose. Eleven species related to seven genera were recorded viz. Aphanoascus durus (1.28%), Arthroderma tuberculatum (3.84%), Arthroderma corniculatum (1.28%), Chrysosporium indicum (16.66%), C. tropicum (3.84%), Ctenomyces serratus (5.12%), Keratinophyton punsolae (1.28%), Microsporum appendiculatum (1.28%), Microsporum gypseum complex (11.53%), Trichophyton mentagrophytes (11.28%) and T. terrestre (2.56%).     

Synthesis,antioxidant, antifungal,molecular docking and ADMET studies of some thiazolyl hydrazones

Some thiazolyl hydrazones were synthesized by one pot reaction of thiophene-2-carbaldehyde or 2, 4-dichlorobenzaldehyde, thiosemicarbazide and various phenacyl bromides which were preliminarily screened for in vitro antioxidant and antifungal activities. Excellent DPPH and H₂O₂ radical scavenged antioxidant activities were observed with almost all the tested compounds. Compounds 4a, 4b, 4c, 4e, 4f and 4i showed comparable DPPH scavenged antioxidant potential (90.26–96.56%) whereas H₂O₂ scavenged antioxidant activity (90.98–92.08%) was noticeable in case of 4a and 4f; showing significant antioxidant potential comparable with the standard ascorbic acid (95.3%). In vitro antifungal activity of synthesized compounds against fungal species Candida albicance, Aspergillus niger and Aspergillus flavus was found to be moderate to good as compared with the standard fluconazole and MIC values were found in the range of 3.12–25 μg/mL. Molecular docking studies revealed that the compounds 4a, 4b and 4c have a potential to become lead molecules in drug discovery process. In silico ADMET study was also performed for predicting pharmacokinetic and toxicity profile of the synthesized antioxidants which expressed good oral drug like behaviour and non-toxic nature.     

Fluorescence‐based sensor for selective and sensitive detection of amoxicillin (Amox) in aqueous medium: Application to pharmaceutical and biomedical analysis

We here for the first time demonstrate an analytical approach for the highly selective and sensitive detection of amoxicillin (Amox) in aqueous medium based on the fluorescence quenching of quantum dots (QDs). The change in fluorescence intensity of mercaptopropionic acid‐capped cadmium sulphide (MPA‐CdS) QDs is attributed to the increasing concentration of Amox. The results show that the fluorescence quenching of QDs by Amox takes place through both static and dynamic types of quenching mechanism. The fluorescence quenching of QDs with increase in concentration of Amox shows the linear range between 5 μg ml^?1 and 30 μg ml^?1 and the limit of detection (LOD) is 5.19 μg ml^?1. There is no interference of excipients, which are commonly present in pharmaceutical formulation and urine samples. For the practical application approach, the developed method has been successfully applied for the determination of Amox in pharmaceutical formulations and urine samples with acceptable results.     

Probing the mechanism of interaction of metoprolol succinate with human serum albumin by spectroscopic and molecular docking analysis

In the present work, the mechanism of the interaction between a β1 receptor blocker, metoprolol succinate (MS) and human serum albumin (HSA) under physiological conditions was investigated by spectroscopic techniques, namely fluorescence, Fourier transform infra‐red spectroscopy (FT‐IR), fluorescence lifetime decay and circular dichroism (CD) as well as molecular docking and cyclic voltammetric methods. The fluorescence and lifetime decay results indicated that MS quenched the intrinsic intensity of HSA through a static quenching mechanism. The Stern–Volmer quenching constants and binding constants for the MS–HSA system at 293, 298 and 303 K were obtained from the Stern–Volmer plot. Thermodynamic parameters for the interaction of MS with HSA were evaluated; negative values of entropy change (ΔG°) indicated the spontaneity of the MS and HSA interaction. Thermodynamic parameters such as negative ΔH° and positive ΔS° values revealed that hydrogen bonding and hydrophobic forces played a major role in MS–HSA interaction and stabilized the complex. The binding site for MS in HSA was identified by competitive site probe experiments and molecular docking studies. These results indicated that MS was bound to HSA at Sudlow's site I. The efficiency of energy transfer and the distance between the donor (HSA) and acceptor (MS) was calculated based on the theory of Fosters' resonance energy transfer (FRET). Three‐dimensional fluorescence spectra and CD results revealed that the binding of MS to HSA resulted in an obvious change in the conformation of HSA. Cyclic voltammograms of the MS–HSA system also confirmed the interaction between MS and HSA. Furthermore, the effects of metal ions on the binding of MS to HSA were also studied.     

Polymerization of acrylamide at acid pH using uranyl nitrate

A new photopolymerizing reagent, uranyl nitrate, is used for the polymerization of acrylamide gels at low pH. The amount of uranyl nitrate (0.2 mg/ml) required for the polymerization of gels at pH 3.0 is considerably less than that of persulfate (7 mg/ml). Use of this reagent obviates the need for the removal of excess of persulfate by preelectrophoresis. The electrophoretic separation of basic proteins in uranium-polymerized gels showed faster movement and better resolution of proteins and proved the gels to be versatile, uniform, and reproducible. Electrophoresis of trypsin in these gels does not affect the enzymatic activity. The catalyst can also be used for the polymerization of gels containing 3 M urea.     

In Vivo Efficacy of a Synthetic Coumarin Derivative in a Murine Model of Aspergillosis

Despite advances in therapeutic modalities, aspergillosis remains a leading cause of mortality. This has necessitated the identification of effective and safe antifungal molecules. In the present study, in vivo safety and antifungal efficacy of a coumarin derivative, N, N, N-Triethyl-11-(4-methyl-2-oxo-2H-benzopyran-7-yloxy)-11-oxoundecan-1-aminium bromide (SCD-1), was investigated. The maximum tolerable dose of compound was determined according to OECD 423 guidelines. The compound could be assigned to category IV of the Globally Harmonized System and its LD₅₀ cut-off was found to be 2000 mg/kg body weight. The survival increased in Aspergillus fumigatus-infected mice treated with a dose of 200 mg/kg, orally or 100 mg/kg body weight, intraperitoneally, of SCD-1 in comparison to infected-untreated animals. The SCD-1 treatment resulted in significant reduction in colony counts in vital organs of the animals. Its protective effect was also observed on day 14 as there was marked reduction in fungal colonies. The treatment with SCD-1 also reduced the levels of serum biochemical parameters with respect to infected-untreated animals. It could be concluded that SCD-1 is a quite safe antifungal compound, which conferred dose dependent protection against experimental aspergillosis. Therefore, SCD-1 holds potential for developing new formulations for aspergillosis.     

Hepatic mixed function oxidase system and effect of phenobarbital, 3-methylcholanthrene and 1, 1, 1-trichloro-2, 2-bis(p-chlorophenyl)ethane in developing chickens.

Contents of hepatic microsomal protein, aminopyrine N-demethylase, acetanilide hydroxylase, aniline hydroxylase, hydrogen peroxide formation, cytochrome-c-reductase, cytochrome b5 and cytochrome P-450 were examined in control, phenobarbital (PB), 3-methylcholanthrene (3-MC) and 1, 1, 1-trichloro-2, 2-bis(p-chlorophenyl)ethane (DDT) treated group of 1-28 days old chickens. Increase in aminopyrine N-demethylase, acetanilide hydroxylase, aniline hydroxylase, cytochrome-c-reductase, cytochrome b5 and cytochrome P-450 was noticed at all stages of development during administration of PB and 3-MC. But these enzyme activities were not always paralleled by increase in age. Aminopyrine N-demethylase was increased in early stages only during DDT administration, which indicates that the form of cytochrome P-450, responsible for aminopyrine N-demethylation is present in early stages only. However, acetanilide hydroxylase was decreased in all stages of development, in postnatal development the basal activities of the enzymes for various substrates do not exhibit identical pattern, the degree of inducibility by inducers varied in relation to age of animal. Hydrogen peroxide formation increased in all stages of developing chickens due to the administration of PB and DDT. It however decreased due to 3-MC administration which may be due to induction of high spin cytochrome P-450.     

Effect of nitrogen supplementation on the longevity of antibiotic production by immobilized cells of Penicillium urticae

Summary Conidia of Penicillium urticae were immobilized in Kappa-Carrageenan beads (2–3 mm) by a previously described procedure to yield an in situ grown immobilized cell population which could be induced to produce the antibiotic and mycotoxin, patulin. When repeatedly transferred into a nitrogen-free production medium every 2 days, the patulin productivity of these cells gradually decreased to 50% within 14 days while the total cell protein remained constant. This decline was due to the gradual loss of the cells' catalytic capacity for converting glucose to 6-methylsalicylic acid (6-MSA), the first metabolite of the patulin pathway, as well as for converting 6-MSA to patulin. When these 14 day-old cells were incubated in a nutrient rich growth medium for 2 days their patulin producing activity increased from 50% to 130%. On the other hand the addition of a protein synthesis inhibitor, cycloheximide, to the N-free production medium drastically reduced the patulin producing activity of the immobilized cells; in particular, their capacity for converting 6-MSA to patulin. The cells' patulin producing activity was maintained at >100% for longer than 15 days when the cells were repeatedly transferred into a yeast extract supplemented production medium or when they were occasionally transferred into 10 or 20% strength growth medium. Repeated transfers to a 10% strength growth medium appeared to stabilize the cells' capacity for converting 6-MSA to patulin.     

Five different enzymatic activities are associated with the multienzyme complex of fatty acid oxidation from Escherichia coli.

The purified multienzyme complex of fatty acid oxidation from Escherichia coli was found to possess 3-hydroxyacyl-coenzyme A (CoA) epimerase and cis-delta3-trans-delta2-enoyl-CoA isomerase activities in addition to the previously identified enoyl-CoA hydratase, L-3-hydroxyacyl-CoA dehydrogenase, and 3-ketoactyl-CoA thiolase activities. Evidence is presented in support of the proposed association of all five enzyme activities with one protein which apparently is composed of two types of subunits and which can exist in several aggregated forms. The five component enzymes of the complex were rapidly inactivated by tris(hydroxymethyl)aminomethane, whereas they remained active in the presence of potassium phosphate.