A theoretical model for water flux through the artery wall

A two layer model for water flux through the artery is studied using a mathematical model based on the theory for the consolidation of water saturated soils. The matrix is considered to be constituted by two layers with different permeabilities and different elastic constants and the two systems of equations are coupled with the condition of continuity of pressure, total stress, solid displacement and fluid seepage velocity at the interface. The luminal pressure is considered to be harmonic in time. Exact solutions are obtained for displacements and pressures in both the layers. For large consolidation times, large pressure gradients are found to exist near the boundaries and at the interface. The heterogeneous model may not only be useful to understand the mechanics of transport in the physiological system but it will also help the bioengineers to choose proper implant materials to design artificial vascular organs for the purpose of prosthesis.     

Molecular cloning,characterization and expression of a nitrofuran reductase gene ofescherichia coli

Mini-mu derivatives carrying plasmid replicons can be used to clone genesin vivo. This method was adopted to generate phasmid clones which were later screened for their ability of restore nitrofurantoin sensitivity of a nitrofuran-resistant host by eliciting nitroreductase activity. One phasmid-derived clone (pAJ101) resulted in considerable increase in nitroreductase activity when introduced into a nitrofurantoin-resistant mutant ofEscherichia coli with reduced nitroreductase activity. Subsequently, a 1.8 kb fragment obtained from pAJ101 by partial digestion with 5au3A, was subcloned into pUC18 to yield pAJ102. The nitroreductase activity attributable to pAJ102 was capable of reducing both nitrofurantoin and nitrofurazone. The polypeptides encoded by pAJ102 were identified by the minicell method. A large, well-defined band corresponding to 37 kDa and a smaller, less-defined band corresponding to 35 kDa were detected. Tnl000 mutagenesis was used to delineate the coding segment of the 1.8 kb insert of pAJ102. A 0.8 kb stretch of DNA was shown to be part of the nitroreductase gene. The gene was mapped at 19 min on theEscherichia coli linkage map.     

Porphinatoiron-mediated oxidation of polycyclic aromatic hydrocarbons

Although porphinatoiron complexes have been used extensively as biomimetic catalysts for oxidation of aliphatic and olefinic hydrocarbons, few oxidations of polycyclic aromatic hydrocarbons (PAH) have been reported. In all cases, heterogeneous iodosobenzene/tetraphenylporphinatoiron(III) systems were employed, oxidations were inefficient and control experiments demonstrating the requirement for catalyst were not described. The current study investigates the oxidation of pyrene, benzo[a]pyrene and benzanthracene in a homogeneous m-chloroperoxybenzoic acid/bifacially hindered porphinatoiron system in which the peroxyacid was shown to be unreactive in the absence of catalyst. Pyrene and benzo[a]pyrene were oxidized efficiently, with pyrene yielding mixtures of 1.6- and 1.8-quinones and benzo[a]pyrene yielding mixtures of phenols and quinones. Benzanthracene was oxidized less efficiently, primarily at the meso positions, to give 7.12-quinone. Initial oxidation of meso carbons of benzo[a]pyrene (confirmed by the presence of the 6-hydroxy derivative as a product) and benzanthracene indicates that PAH-to-catalyst charge transfer may be an important oxidation pathway. Oxidation of pyrene was performed by addition of pyrene to observable oxo iron(V) species as well as in a catalytic reaction where excess peroxyacid was added to a solution of pyrene and catalyst and oxo iron(V) is not generated as an observable intermediate. Yields (based on oxidant consumed), were identical under both conditions, strongly supporting oxo iron(V) as a common intermediate.     

Inhibitors of nitrofuran reduction in Escherichia coli: evidence for their existence, partial purification, binding of nitrofurantoin in vitro, and implications for nitrofuran resistance

Nitrofurantoin (NF)-resistant mutants of Escherichia coli were isolated as described previously (18). One of the mutants (SSJ-2) was found to possess NF reductase activity equal to that of its parent (E. coli KL16). Two NF-resistant transductional derivatives, SSJ-2A and SSJ-2B, were isolated using SSJ-2 as the donor. SSJ-2 was found to be a double mutant carrying two mutations, nfnA and nfnB, while SSJ-2A (nfnA) and SSJ-2B (nfnB) carried these mutations individually. Heated extracts from SSJ-2A and SSJ-2B were found to inhibit the reduction of NF by unheated extracts of the NF-sensitive strain E. coli KL16 in vitro. Unheated extracts of these mutants reduced NF poorly relative to E. coli KL16. The poor reduction of NF by unheated extracts of SSJ-2A and SSJ-2B was greatly stimulated by heated extracts of SSJ-2B and SSJ-2A, respectively, and also by heated extracts of E. coli KL16. When heated extracts of SSJ-2A and SSJ-2B were mixed in a particular ratio and added to unheated extracts of E. coli KL16 they lost their inhibitory activity. Two proteins, designated inhibitor A and inhibitor B, have been partially purified from heated extracts of SSJ-2B and SSJ-2A, respectively. Their respective molecular weights, as determined by gel chromatography, were 37,000 and 20,500. The two inhibitors bound nitrofurantoin in vitro, and the NF-binding ability was lost when mixed in the molar ration of 3/1 (B/A). These observations were rationalized in terms of a hypothesis which explains (i) maximal NF reduction in wild-type cells, (ii) maximal NF reduction of nfnA-nfnB- double mutant, and (iii) poor NF reduction in nfnA- or nfnB- single mutants. The possible role of these inhibitors in nitrofurantoin resistance is also discussed.     

Identification of the peptides of the crystals of Bacillus thuringiensis var israelensis involved in the mosquito larvicidal activity

Tryptic digestion of the proteins from the purified crystals of B.thuringiensis var israelensis resulted in the decline of high molecular weight peptides without the loss of mosquito larvicidal activity, measured after immobilization of the digests with DEAE- Sephadex A 50 beads. Amongst the peptides generated (less than 44 kDa), a 21 kDa peptide was immunoreactive to the crystal antiserum. Analysis of the peptides released from spores of the toxic (Cry+) and non-toxic (Cry-) strains has revealed a pattern in which only the 26kDa peptide was missing in the Cry-strain. Sporulation and crystal formation were dissociated by the addition of the antibiotic netropsin, which could also inhibit the crystal assembly, without considerable decrease of the larvicidal activity and retention of the 26kDa peptide. These results implicate the 26kDa peptide in the larvicidal action.     

Monitoring ovulation and implantation in the cynomolgus macaque (Macaca fascicularis) through evaluations of urinary estrone conjugates and progesterone metabolites: a technique for the routine evaluation of reproductive parameters

Investigations were undertaken to determine the applicability of recently reported specific radioimmunoassays for urinary estrone conjugates and progesterone metabolites for monitoring ovarian function in the cynomolgus macaque (Macaca fasciularis) and other macaque species. Mean estrone conjugate measurements appear to accurately reflect the preovulatory estrogen peak in both conceptive (n = 5) and nonconceptive (n = 6) cycles, as well as to indicate early pregnancy through increases which are significantly elevated by Day + 15 (p less than 0.049) post estrone conjugates peak. The mean luteal phase levels of these progesterone metabolites are significantly elevated by Day + 14 (p less than 0.012) in conceptive cycles when compared to the mean values for nonconceptive cycles.     

Influence of sowing times of castor varieties on their resistance to the leafhopper, Empoasca flavescens (Homoptera, Jassidae)

The possible influence of sowing times on the resistance of the castor varieties R.C. 1098 Baker (jassid-resistant), Dominaca (susceptible) and C3 Pakistan (tolerant) was studied at five sowing dates ranging from early to late in the season. Infestation, hopperburn and yield-reduction of Dominica variety were significantly higher in the later sowings than in the earlier ones, and early sowing of this variety may result in decrease of insect damage.In another field experiment the three varieties were sown early and yield-reductions were 44% (Dominica), 11% (C3 Pakistan) and 4% (R.C. 1098 Baker). The two last mentioned varieties appeared consistent in their degree of resistance in all sowings. There was no evidence about pseudo-resistance due to host evasion and/or escape.

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Zusammenfassung Es wurde eine Untersuchung mit der gegen Jassiden resistenten Rizinussorte R.C. 1098 Baker sowie der anfälligen Sorte Dominica und der toleranten C3 Pakistan während der Vegetationsperiode 1963–'64 in Südindien durchgeführt. Dabei sollte der mögliche Einfluss der Saatzeit auf die Resistenz oder Anfälligkeit dieser Rezinussorten gegenüber Empoasca flavescens festgestellt werden. Es konnte einwandfrei nachgewiesen werden, dass der Jassidenbefall, der Schaden (hopperburn) und der negative Einfluss auf den Ertrag bei der anfälligen Sorte Dominica bei den späteren Saatzeiten signifikant stärker was als in den früheren. Es wird deshalb der Schluss gezogen, dass frühere Aussaatzeit der anfälligen Sorte als eine Methode der Verminderung von Jassidenschaden angewendet werden kann.Der absolute Prozentsatz der Ertragsreduktion bei der anfälligen Sorte wurde selbst bei früherer Saatzeit mit 44% gegenüber nur 11% bei der toleranten und 4% bei der resistenten Sorte festgestellt. Die Sorten C3 Pakistan und R.C. 1098 Baker verhielten sich in allen Saatzeiten unverändert hinsichtlich ihres Resistenzgrades. Pseudo-Resistenz durch host evasion oder escape konnten in diesen Fällen nicht beobachtet werden.

     

Enhancement of in vivo cell-mediated immune responses by three distinct cytokines

The ability of recombinant/purified cytokines to augment delayed-type hypersensitivity (DTH) responses was investigated. Suboptimal doses of haptenized SC were treated in vitro with purified or recombinant derived cytokines and tested for their ability to enhance DTH in vivo. With the use of this protocol, it was shown that both human and mouse rIL-6, as well as mouse rTNF-alpha, potentiated DTH in a dose-dependent manner. In accordance with these data, IL-6/TNF-alpha-containing supernatant from long term nonlymphoid cell lines also possessed the ability to augment DTH. By using the same protocol, we have also identified T cell hybridomas that produce DTH-augmenting activity constitutively. The hybridoma-derived factor, termed the T cell enhancing factor (TCEF), was functionally distinguishable from the defined cytokines IL-1 through IL-6, IFN-gamma, and TNF by bioassay. Furthermore, RNA derived from the hybridoma failed to hybridize with cDNA probes specific for IL-1 to IL-6, IFN-gamma, TNF-alpha, and granulocyte-macrophage CSF. Further characterization of the serum-free conditioned media derived from the hybridoma indicated that the TCEF was a soluble acid labile glycoprotein (Mr greater than 30,000). Finally, we investigated the cellular requirements for DTH augmentation by IL-6, TNF-alpha, and TCEF; all are dependent upon the presence of T cells in the immunizing inoculum. We propose that these cytokines play a critical role in the development of DTH responses in vivo.