Effect of surfactants on α‐amylase production in a solid substrate fermentation process

Solid substrate fermentation (SSF) is a process where the substrate is a moist solid, which is insoluble in water but not suspended in water. In this study SSF of Bacillus subtilis (ATCC 21556) was used to produce an enzyme of commercial importance, α‐amylase, using as a substrate potato peel. To enhance the production of this enzyme, two nonionic synthetic surfactants were used, Tween 80 and Tween 20, one anionic surfactant, SDS at concentrations of 0.05% and 0.10% (v/w) and a biosurfactant produced by Bacillus subtilis (ATCC 21332), known as surfactin, at concentrations of 0.003%, 0.007%, 0.013% and 0.03% (w/w). The results have shown that surfactants significantly increase the production of α‐amylase. Tween 80 at 0.10% and surfactin at 0.013% provided the highest enzyme activity when compared with the control. © 1999 Society of Chemical Industry     

Dielectric analysis of the cure of thermosetting epoxy/amine systems

A low molecular weight epoxy resin is cured isothermally with an aromatic amine hardener, and the dielectric properties are measured as a function of the frequency, reaction time, and cure temperature. At specific stages in the cure, small samples from the reacting mixture are quenched and subsequently analyzed for the glass transition temperature and epoxy group conversion by differential scanning calorimetry. In this manner, the change In dielectric properties can be directly correlated with the network structure. The ionic conductivity is modeled as a function of the cure temperature and the cure-dependent glass transition temperature using a Williams-Landel-Ferry (WLF) relation. Combining this WLF relation with the DiBenedetto equation, a comprehensive model relating conductivity with the extent of reaction and cure temperature has been developed.     

Recent advances in aqueous two-component systems for heavy-duty metal protection

Although waterborne coatings have successfully replaced their solventborne counterparts in a variety of areas, their use generally has been limited to applications with relatively modest performance requirements. Recently, advances in technology have allowed for the design of waterborne coatings with performance suitable for more demanding applications. The emergence of two-component waterborne polyurethane coatings exemplifies this trend. These coatings can provide performance similar to that of solventborne 2-pack urethanes, but with much lower VOC. The chemistry of these coatings is discussed, in light of its relevance to some of the technical challenges, e.g., pot life and CO₂-gassing in thick films, unique to these systems. The use of 2-pack waterborne urethane topcoats in combination with low VOC waterborne acrylic/epoxy primers and intermediate coats is also described. Such multiple coat systems offer the promise of long term corrosion protection in severe industrial and marine environments, coupled with very low VOC.     

Experimental study of warm-air defrosting of heat-pump evaporators

The defrosting of a heat-pump evaporator with warm air has been investigated experimentally under controlled conditions in an air-conditioned wind tunnel. The work was initiated to explore the possibility of defrosting an evaporator under conditions where a heat pump continues to perform heating duty. A four-row straight-fin heat exchanger was used, supported from below by a load transducer to measure its weight variation during both frost accumulation and removal. The rate of melting was determined as a function of air temperature, relative humidity and velocity. The removal from the evaporator surfaces of water produced by defrosting was found to be dependent on air velocity. Proposals are advanced for further experimental studies.     

Annular pupils, radial polarization, and superresolution

An annular pupil, which can be used to produce a Bessel beam, when combined with radially polarized illumination promises improvements in microscope resolution, increased packing density for optical storage, and finer optical lithography. When combined with a circular detection pupil in confocal microscopy a point-spread function 112 nm wide results (lambda = 488 nm). Radially polarized annular illumination of a solid-immersion lens can yield a focal spot smaller than 100 nm for lambda = 488 nm. Use of radially polarized illumination with pupil masks is discussed.     

Transgenic N-myc mouse model for indolent B cell lymphoma: tumor characterization and analysis of genetic alterations in spontaneous and retrovirally accelerated tumors

Little is known about stepwise deregulation of specific genes leading to lymphoid malignancy. Aberrant myc gene expression in transgenic mice is correlated with B cell lymphomagenesis. We generated a unique transgenic mouse model in which deregulated murine E mu-N-myc transgene expression leads to development of indolent B cell lymphoma. Tumor cells were monoclonal, morphologically mature and surface immunoglobulin expressing B cells. Tumors arose in a disease course and exhibited a cytoarchitectural appearance reminiscent of human follicular lymphoma. Yet tumor cells were staged as preB since they failed to rearrange the immunoglobulin light chain genes. Retroviral insertion mutagenesis analyses of adult transgenic mice infected as newborns with murine leukemia virus revealed decreased disease latency, increased lymphoma incidence and a histologically more mature tumor type. Proviral insertion sites were not equivalent when accelerated E mu-N-myc indolent lymphomas were compared to accelerated c-myc preB cell lymphomas. The bcl-2 gene was not disrupted in either spontaneous or provirally accelerated E mu-N-myc lymphomas. These findings suggest that tumor progression in N-myc-associated indolent B cell lymphoma can proceed along diverse pathways involving distinctly different combinations of deregulated and/or intact genes than those pathways described in highly aggressive forms of myc-related murine preB cell disease.     

Susceptibility of Peromyscus leucopus and Mus musculus to infection with Baylisascaris procyonis

In this study, we compared the susceptibility of Peromyscus leucopus (white-footed mouse), a common natural intermediate host, and Mus musculus, a commonly used experimental model, to infection with larvae of the raccoon ascarid, Baylisascaris procyonis. Three groups of 10 mice of each species were given 50, 250, or 500 infective B. procyonis eggs by gavage. The mice were observed daily for clinical signs of central nervous system (CNS) disease and at necropsy the distribution of larvae in 10 body regions and organs was determined and compared. Clinical CNS disease developed in 57% of P. leucopus and 93% of M. musculus. The average clinical incubation period was significantly longer in P. leucopus (20.6 days postinfection [PI]) than in M. musculus (10.7 days PI), and clinical disease progressed slower in P. leucopus. Significantly fewer larvae were recovered from P. leucopus than from M. musculus. Most larvae were recovered from the anterior carcass and viscera of P. leucopus and from the carcass, head, and brain of M. musculus. CNS invasion was dose dependent in M. musculus but not in P. leucopus. Few or no grossly visible larval granulomas were present in P. leucopus but were abundant in M. musculus. We concluded that P. leucopus was less susceptible than M. musculus to B. procyonis infection, based on a decreased intensity of infection, longer clinical incubation period or lack of clinical disease, slower progression of disease, different larval distribution, and lower tissue reactivity to larvae.     

Retinoid X receptor expression in the normal pituitary and clinically ''non-functioning'' pituitary tumours

Nasal chondromesenchymal hamartoma is the suggested appellation for a tumefactive process of the nasal passages and contiguous paranasal sinuses in seven children with a detectable mass in the nose. With the exception of one patient who was 7 years of age at diagnosis, the others were 3 months of age or less upon recognition of the mass. Two children were diagnosed in the first 2 weeks of life. Imaging studies showed a complex solid and cystic mass or masses filling the nasal cavity and extending into the ethmoid sinuses in most cases. Erosion of the surrounding bone, including the cribriform plate, resulted in an intracranial component in the four cases. Surgical resection was the treatment of choice despite its technical difficulties that often necessitated a combined intranasal and intracranial approach. Residual disease with continued growth in one case was the clinical outcome in two children, and the remaining five patients have not experienced any further difficulties. The piecemeal fragments of tissue disclosed a collage of histologic features, but the basic morphologic elements were well-demarcated nodules of cartilage with some variation in the cellular density and maturation of the chondrocytes, a myxoid to spindle cell stroma, focal osteoclastlike giant cells in the stroma, and erythrocyte-filled spaces resembling those of the aneurysmal bone cyst. Two of the tumors were less polymorphous or complex in their spectrum of histologic features. These nasal masses have similarities to the so-called chest wall hamartoma or mesenchymal hamartoma of the chest wall in terms of the clinical presentation in infancy and the basic cartilaginous character of both entities. There is a degree of presumption in the designation of these nasal and chest wall tumors as hamartomas because the pathogenesis has not been established for either entity.     

Role of P-selectin and leukocyte activation in polymorphonuclear cell adhesion to surface adherent activated platelets under physiologic shear conditions (an injury vessel wall model)

Carbohydrate moieties on leukocytes adhere to activated platelets via P-selectin under static binding condition studies. We characterize polymorphonuclear cell (PMN) surface interactions with surface adherent platelets and the PMNs response, under physiologic flow conditions corresponding to a shear of 100 s-1, in an in vitro flow chamber. Fluorescent labeled PMNs with red blood cells were drawn through a transparent flow channel and visually quantitated over 30 minutes, interacting with a confluent monolayer of activated, shear-spread platelets expressing P-selectin. PMN adhesion was saturable (2,250 +/- 350/mm2), and time and cation (Ca2+, Mg2+) dependent, and PMNs did not bind to the experimental surface in the absence of a platelet monolayer. P-selectin antibodies completely abolished PMN adhesion in a concentration-dependent manner with half inhibition at 70 micrograms/mL. Antibodies to a putative P-selectin receptor CD15 (80H5 and MMA) maximally inhibited PMN adhesion by 73% and 10%, respectively. Adherent PMNs appeared morphologically activated and flow cytometric analysis of adherent PMNs confirmed activation because CD11b and CD18 surface expression was upregulated (100% and 27%, respectively), whereas L-selectin was downregulated (55%) compared with control nonadherent PMNs. In the presence of the metabolic inhibitor sodium azide (0.02% and 0.1%) there was a 23% +/- 9% and 51% +/- 3% decrease, respectively, in PMN adhesion at 100 s-1. Thus, P-selectin is required for PMN adhesion to a pathophysiologic surface of activated adherent platelets at physiologic shear rates. Furthermore, a secondary step involving PMN activation after platelet binding appears necessary for complete (irreversible) adhesion to occur. This unique flow cell provides a model to explore, under controlled conditions, biologic mechanisms and ligands involved in leukocyte-platelet binding that play important roles in PMN localization at sites of thrombosis and vascular injury.     

Bone mineral density in thyroxine treated females with or without a previous history of thyrotoxicosis

Alterations in lipid metabolism characterized in major part by a decrease in lipoprotein lipase (LPL) activity in adipose tissue are a central feature of cachexia from chronic infection or malignancy. These metabolic derangements may be mediated in large part through endogenous host proteins produced in response to various pathological stimuli. Differentiation factor/leukaemia inhibitory factor (D-factor) is a cytokine whose functions overlap those of tumour necrosis factor-alpha (TNF), IL-6 and IL-1. Recombinant murine D-factor produced a dose- and time-dependent inhibition of heparin-releasable LPL activity in differentiated 3T3-L1 adipocytes. Although 2-10 fold less potent than recombinant murine TNF, D-factor inhibited LPL activity at concentrations of 1-10 ng/ml. When added together, D-factor and TNF produced a synergistic inhibition of LPL activity. Interleukin 6 (IL-6) was 100-fold less potent than D-factor; 0.1 ng/ml of D-factor or 10 ng/ml of IL-6 caused a 50% inhibition of LPL activity. D-factor and TNF increased IL-6 production in 3T3-L1 cells. Ten ng/ml of D-factor or 1.0 ng/ml of TNF stimulated the release of < 1 ng/ml of IL-6 and inhibited LPL activity to 11 +/- 3% and 3 +/- 2% of control, respectively, whereas 50 ng/ml of recombinant IL-6 was required to decrease LPL activity to 24 +/- 19% of control. TNF produced a marked decrease in LPL mRNA, whereas D-factor had minimal or no effect at doses which inhibited LPL activity almost completely. Western blot analysis of cell extracts showed that TNF caused a greater decrease in LPL protein production than D-factor.2+ with TNF, may contribute to the manifestations of cachexia.