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  • Biochemistry and Biotechnology  (57)
  • Life and Medical Sciences  (56)
  • Wiley-Blackwell  (113)
  • American Institute of Physics
  • Springer Nature
  • 1995-1999  (113)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 30 (1995), S. 208-217 
    ISSN: 1059-910X
    Keywords: Superconductors ; Electron energy loss spectrometry ; Transmission electron microscope ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Electron energy loss spectrometry (EELS) with a cold field emission gun (cFEG) transmission electron microscope (TEM) is implemented to analyze the evolution of the electronic structure and dielectric function of oxide superconductors. The O-K core loss spectra of p-type doped oxide superconductors are analyzed in terms of holes formation on oxygen sites, while low loss spectra are analyzed for free carrier plasmas, other spectral excitations, and their crystallographic confinement.It is illustrated that the transmission EELS with a cFEG TEM very much complement soft X-ray absorption spectroscopy and optical spectroscopy, with the added advantages of high spatial resolution (∼1-100 nm), and is compatible with other analytical, diffraction, and imaging techniques, which are readily available in a cFEG TEM. © 1995 Wiley-Liss, Inc.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 40 (1995), S. 228-232 
    ISSN: 1040-452X
    Keywords: Gossypol ; Sperm ; Acrosomal enzymes ; Rabbit ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The effect of gossypol on the activities of 10 acrosomal enzymes of the rabbit sperm was evaluated. Acrosin, Azocoll proteinase, neuraminidase, and arylsulfatase were significantly inhibited or completely inactivated by 12-76 μM gossypol. Hyaluronidase, β-glucuronidase, and acid phosphatase were inhibited only at a higher concentration of gossypol (380 μM). Phospholipase C, alkaline phosphatase, and β-N-Acetyl glucosaminidase were not inhibited even at 380 μM gossypol. Gossypol was found to be a noncompetitive inhibitor of arylsulfatase with a Ki of 120 μM. The inhibition was reversible and dose-dependent. As the acrosomal enzymes were more sensitive to the inhibition by gossypol compared to sperm enzymes involved in glycolysis or energy production, these assays may serve as a more reliable indicator for monitoring the occurence of gossypol-induced sterility. © 1995 Wiley-Liss, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 16 (1995), S. 70-74 
    ISSN: 0197-8462
    Keywords: video display terminals ; embryogenesis ; teratology ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Eighty-nine Swiss Webster mice were randomly divided into four groups: a control group, a pulsed magnetic field (PMF) group, a cytosine arabinoside (ara-C, a teratogen) group, and, a combined PMF + ara-C group. Mice in the PMF and PMF + ara-C groups were irradiated with a PMF (a sawtooth waveform with 52 μs rise time, 12 μs decay time, and 15.6 kHz frequency) at a peak magnetic flux density of 40 μT for 4 hours daily on days 6-17 of gestation. The mice in the ara-C and the PMF + ara-C groups were injected intraperitoneally on day 9 of gestation with 10 mg/kg of ara-C. The incidence of resorption and dead fetuses was not affected by PMF but was increased by ara-C injection. The malformation incidence of cleft palate (CP) and/or cleft lip (CL) was significantly higher in all three of the treated groups than in the control group (P 〈 0.05). If, however, statistical analyses had been done on litters rather than on individual fetuses, they would show that the incidence of CP and/or CL in the PMF group is not significantly greater than that in the control group. A significantly higher incidence of CP and/or CL was found in the PMF + ara-C group (49%) than the ara-C alone group (26.1%). These data suggest that PMF might enhance the development of ara-C-induced CP and/or CL. The incidence of minor variations in skeletal development, including reduction of skeletal calcification and loss of skeleton, was not statistically significant in the PMF group. However, it was higher in the two ara-C-treated groups, and there was no significant difference between the ara-C alone group and the ara-C + PMF group. From these results it is concluded that the very weak embryotoxic effects of PMF exposure may be revealed and enhanced in combination with a teratogenic agent. © 1995 Wiley-Liss, Inc.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 204-216 
    ISSN: 0006-3592
    Keywords: expanded bed adsorption ; bakers' yeast ; G6PDH ; STREAMLINE ion exchange adsorbents ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The use of expanded beds of STREAMLINE ion exchange adsorbents for the direct extraction of an intracellular enzyme glucose-6-phosphate dehydrogenase (G6PDH) from unclarified yeast cell homogenates has been investigated. It has been demonstrated that such crude feedstocks can be applied to the bed without prior clarification steps. The purification of G6PDH from an unclarified yeast homogenate was chosen as a model system containing the typical features of a direct extraction technique. Optimal conditions for the purification were determined in small scale, packed bed experiments conducted with clarified homogenates. Results from these experiments were used to develop a preparative scale separation of G6PDH in a STREAMLINE 50 EBA apparatus. The use of an on-line rotameter for measuring and controlling the height of the expanded bed when operated in highly turbid feedstocks was demonstrated. STREAMLINE DEAE has been shown to be successful in achieving isolation of G6PDH from an unclarified homogenate with a purification factor of 12 and yield of 98% in a single step process. This ion exchange adsorbent is readily cleaned using simple cleaning-in-place procedures without affecting either adsorption or the bed expansion properties of the adsorbent after many cycles of operation. The ability of combining clarification, capture, and purification in a single step will greatly simplify downstream processing flowsheets and reduce the costs of protein purification. © 1996 John Wiley & Sons, Inc.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 715-726 
    ISSN: 0006-3592
    Keywords: fungal morphology ; pellets ; hyphae ; hair of pellets ; agitation intensity ; fermentation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Both parallel fermentations with Aspergillus awamori (CBS 115.52) and a literature study on several fungi have been carried out to determine a relation between fungal morphology and agitation intensity. The studied parameters include hyphal length, pellet size, surface structure or so-called hairy length of pellets, and dry mass per-wet-pellet volume at different specific energy dissipation rates. The literature data from different strains, different fermenters, and different cultivation conditions can be summarized to say that the main mean hyphal length is proportional to the specific energy dissipation rate according to a power function with an exponent of -0.25 ± 0.08. Fermentations with identical inocula showed that pellet size was also a function of the specific energy dissipation rate and proportional to the specific energy dissipation rate to an exponent of -0.16 ± 0.03. Based on the experimental observations, we propose the following mechanism of pellet damage during submerged cultivation in stirred fermenters. Interaction between mechanical forces and pellets results in the hyphal chip-off from the pellet outer zone instead of the breakup of pellets. By this mechanism, the extension of the hyphae or hair from pellets is restricted so that the size of pellets is related to the specific energy dissipation rate. Hyphae chipped off from pellets contribute free filamentous mycelia and reseed their growth. So the fraction of filamentous mycelial mass in the total biomass is related to the specific energy dissipation rate as well.To describe the surface morphology of pellets, the hyphal length in the outer zone of pellets or the so-called hairy length was measured in this study. A theoretical relation of the hairy length with the specific energy dissipation rate was derived. This relation matched the measured data well. It was found that the porosity of pellets showed an inverse relationship with the specific energy dissipation rate and that the dry biomass per-wet-pellet volume increased with the specific energy dissipation rates. This means that the tensile strength of pellets increased with the increase of specific energy dissipation rate. The assumption of a constant tensile strength, which is often used in literature, is then not valid for the derivation of the relation between pellet size and specific energy dissipation rate. The fraction of free filamentous mycelia in the total biomass appeared to be a function of the specific energy dissipation in stirred bioreactors. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 715-726, 1997.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 30 (1995), S. 17-25 
    ISSN: 0886-1544
    Keywords: rotation ; twisting ; microtubule-dynein complex ; 22S dynein ; dynein-track ; ATP ; sliding ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Applying a new in vitro motility assay system for microtubules and 22S dynein, we recently reported on an ATP-induced extrusion of microtubules from microtubule-dynein α- and β-complexes [Mimori and Miki-Noumura, 1994:Cell Motil. Cytoskeleton 27:180-191]. In the present study, we prepared a γ-complex by copolymerizing porcine brain tubulin and Tetrahymena ciliary 22S dynein, and examined the ATP-induced microtubule movement from the γ-complex. The extrusion process appeared quite similar to that of the β-complex. The sliding velocity was 18.39 ± 2.20 m̈m/sec, which was a value comparable to that of trypsin-digested flagellar axonemes [Yano and Miki-Noumura, 1980:J. Cell Sci. 44:169-186]. Higher velocity may be due to a densely arranged dynein-track with the same polarity, which was detached from the γ-complex and absorbed in rows on a glass surface of the slide. Sometimes a free-floating microtubule in the perfusion chamber was observed riding and sliding on the dynein-track remaining on the slide after extrusion.Unexpectedly, we found that when the front part of the microtubule was fixed to a glass surface, a continuous sliding microtubule at the rear part on the dyneintrack often transformed into a left-handed helix, and subsequently a twisted helix with several turns. The helix formation may be due to some rigidity in the microtubule and a right-handed torque component in the sliding force of 22S dynein. The addition of ATP may release some distortion accumulated in the complex structure during copolymerization of tubulin and 22S dynein, inducing reverse rotation of the microtubule. © 1995 Wiley-Liss, Inc.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 278-288 
    ISSN: 0006-3592
    Keywords: affinity chromatography ; biomimetic dye ; Candida boidinii ; enzyme purification ; oformate dehydrogenase ; triazine dye ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Formate dehydrogenase (FDH, EC 1.2.1.2) was purified from Candida boidinii cells in a single step by biomimetic-dye affinity chromatography. For this purpose, seven' biomimetic analogues of the monochlorotriazine dye, Cibacron® Blue 3GA (CB3GA), and parent dichloro-triazine dye, Vilmafix® Blue A-R (VBAR), bearing a car-boxylated structure as their terminal biomimetic moiety, were immobilized on crosslinked agarose gel, Ultrogel® A6R. The corresponding new biomimetic-dye adsorbents, along with nonbiomimetic adsorbents bearing CB3GA and VBAR, were evaluated for their ability to purify FDH from extracts obtained after press-disintegration of C. boidinii cells. Optimal conditions for maximizing specific activity of FDH in starting extracts (1.8 U/mg) were realized when cell growth was performed on 4% methanol, and press disintegration proceeded in four consecutive passages before the homogenate was left to stand for 1 h (4°C). When compared to nonbiomimetic adsorbents, biomimetic adsorbents exhibited higher purifying ability. Furthermore, one immobilized biomimetic dye, bearing as its terminal biomimetic moiety mercap-topyruvic acid linked on the chlorotriazine ring (BM6), displayed the highest purifying ability. Adsorption equilibrium data which were obtained for the BM6 adsorbent in a batch system corresponded well to the Langmuir isotherm and, in addition, breakthrough curves were taken for protein and FDH adsorption in a fixed bed of BM6 adsorbent. The dissociation constant ( KD) of the complex between immobilized BM6 and FDH was found to equal 0.05 μM. Adsorbent BM6 was employed in the purification of FDH from a 18-L culture of C. boidinii in a single step (60% overall yield of FDH). The purified FDH afforded a single-band on sodium dodecyl sulphate poly-acrylamide gel electrophoresis, and a specific activity of 7,0 U/mg (30°C). © 1995 John Wiley & Sons, Inc.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 520-528 
    ISSN: 0006-3592
    Keywords: human growth hormone ; animal cell culture ; purification ; serum ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Human growth hormone (hGH) is a polypeptide with 191 amino acids and a molecular mass of 22 kilodaltons. With the aid of computer molecular simulation, an hGH analog was created by altering an hGH gene to reflect the change of one amino acid (glycine [G] 120 to arginine [R]) within the third α-helix of the hGH molecule. This hGH analog, named hGHG120R, was found to be an hGH antagonist. It may have important implications in treating human conditions in which hGH levels are abnormally high, as found in type I diabetics. Several hundred milligrams of purified hGHG120R were needed to determine the biological activity of the antagonist in animal models. A multistep downstream process was developed to purify hGHG120R from cultured mouse L cells transfected with the hGHG120R gene. The process consisted of cell clarification, salt precipitation, membrane ultrafiltration, reversed phase high performance liquid chromatography, phase separation, and lyophiliation. This work discusses the rationale for the design of the process and experimental results on the purification of hGHG120R using the process. © 1995 John Wiley & Sons, Inc.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 288-297 
    ISSN: 0006-3592
    Keywords: protein purification ; peptide libraries ; ligands ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Peptide libraries can be used to identify ligands that bind specifically to a desired protein. These peptides may have significant advantages as specific ligands for affinity chromatography separations. This article describes the use of one of such peptide, Try-Asn-Phe-Glu-Val-Leu, as a ligand for the purification of S-protein using affinity chromatography. General strategies for peptide immobilization are discussed and the conditions for peptide immobilization to Emphaze™ gel are optimized. The effects of peptide orientation and peptide densities on protein binding are studied. Results indicate that the peptide affinity is not affected by the orientation of the peptide during immobilization, but association constants can be reduced by one order of magnitude when compared with the values in solution.With increased peptide density, the protein binding capacity of the gel increases, but both the percentage of peptide utilization and apparent binding constant between immobilized peptide and S-protein decrease. S-protein is separated from a mixture with BSA via affinity chromatography using specific elution with the peptide in solution.Finally, direct purification of S-protein from an enzymatic digestion mixture of ribonuclease A is demonstrated.© 1995 John Wiley & Sons, Inc
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  • 10
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 59 (1995), S. 227-232 
    ISSN: 0730-2312
    Keywords: Color doppler imaging ; HER-2/neu oncogene ; ovarian cancer screening ; ultrasound ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The inability to identify relevant markers for presymptomatic screening in early stage or “preinvasive” ovarian cancer had plagued investigators and clinicians facing the problems of early detection. The characteristic late stage of disease at initial presentation has hindered our understanding of the biologic progression and stepwise molecular alterations that result in ovarian carcinoma. To date, most screening studies have focused on identifying early anatomic changes using ultrasound or fluctuations in serum biomarkers such as CA-125. These screening methodologies have proven inadequate in both sensitivity and specificity for early stage ovarian cancer detection.Molecular analysis of ovarian carcinomas has revealed alterations in oncogenes and tumor suppressor genes associated with these tumors. The HER-2/neu oncogene, a member of the epidermal growth factor family, is amplified or overexpressed in approximately 25-30% of ovarian carcinomas. Significant data substantiate an important role for HER-2/neu in the pathophysiology of ovarian cancer. While potentially an attractive surrogate endpoint biomarker (SEB), serum HER-2/neu levels have not proven to be a useful screening modality.In response to the urgent need for improved early detection for ovarian cancer, our current research efforts include differential hybridization studies between normal and malignant ovarian epithelium to define potentially unique ovarian cancer antigens which may ultimately have clinical utility; defining physical alterations that occur in malignant ovarian tissues using implanted telemetry systems; studies using positron emission tomography to detect changes in glucose metabolism between normal and malignant ovarian tissues; and screening studies using a 3-dimensional ultarsound unit to improve the accuracy of this technique in recognizing early neoplastic changes. By taking diverse approaches to tackle this problem, an improved understanding of ovarian carcinogenesis should translate into the identification of appropriate SEBs for early detection.
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