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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 25 (1983), S. 1295-1310 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Flow cytometry is a fast and sensitive method that allows monitoring of different cellular parameters on large samples of a population. Protein distributons give relevant information on growth dynamics, since they are related to the age distribution and depend on the law of growth of the population and the law of protein accumulation during the cell cycle. We analyzed protein distributions to evaluate alternative growth models for the budding yeast Saccharomyces cerevisiae and to monitor the changes in population dynamics that result from environmental modifications; such an analysis could potentially give parameters useful in the control of biotechnological processes. Theoretical protein distributions (taking into account the unequal division of yeast cells and the exponential law of protein accumulation during a cell cycle) quantitatively fit experimental distributions, once appropriate variability sources are introduced. Best fits are obtained when the protein threshold required for bud emergence increases at each new generation of parent cells.
    Additional Material: 8 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 1322-1330 
    ISSN: 0006-3592
    Keywords: segregated models ; hybridoma cell ; antibody productivity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Several experimental data on continuous cultures of hybridoma cells show that monoclonal antibody productivity is a decreasing function of dilution rate. It has been suggested that this unusual behavior may be due to the arrest of a fraction of cycling cells at a critical point of Phase G1. Although this hypothesis has been recently investigated by using population balance models, mathematical analysis has been performed without accounting for the dynamics of the arrested cells properly. In this article, a more general and accurate approach is presented and new specific assumptions are introduced to characterize the arrest and the later progress through the cycle. Two different models (stochastic and deterministic) and two different critical points for the arrest (at the beginning and at the end of G1) are considered. The cell cycle parameters are estimated so that data predicted by the model fit those reported in the literature. In particular, the fraction of arrested cells, the cell arrest probability, and the mean cell generation time are computed as functions of the dilution rate. Results so far obtained predict that there is an optimal value of dilution rate for maximizing specific production rate of monoclonal antibody. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 3
    ISSN: 0730-2312
    Keywords: chemoprevention ; fenretinide ; oral leukoplakias ; clinical trials ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: A controlled clinical trial has been underway at the Istituto Nazionale Tumori (INT) of Milan since 1988. The goal of the trial is to evaluate the effectiveness of fenretinide (4-HPR) in preventing relapses, new localizations, and carcinomas in patients with benign postoperative diagnoses who have been surgically treated for oral leukoplakias. This paper presents the design and the preliminary results of this study. To date, 137 patients have been randomized, following surgical excision of oral leukoplakia, to receive either 200 mg 4-HPR daily for 52 weeks or no intervention. Twenty local relapses or new localizations have occurred so far in the control group and 9 in the 4-HPR group. Seven patients have interrupted the intervention because of toxicity. No impaired dark adaptation has been observed. We conclude that 4-HPR is well-tolerated and appears to be effective in preventing relapses and new localizations during the treatment period.
    Additional Material: 2 Ill.
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  • 4
    ISSN: 0730-2312
    Keywords: 4-HPR ; chemoprevention ; fenretinide ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: We are conducting three randomized studies (breast cancer, basal cell carcinoma, oral leukoplakia) and report our methodological approach and accrual here.The aim of the breast cancer study is prevention of a contralateral primary lesion in women already treated for breast cancer; the aim of the basal cell carcinoma study is prevention of recurrences or new occurrence after surgical resection; and the aim of the oral leukoplakia study is prevention of recurrences and new occurrence after CO2 laser resection. The studies were planned according to a randomized design with an intervention arm vs a no-treatment arm. Patients in the intervention group receive 4-HPR at a dose of 200 mg po. The duration of treatment is five years in the breast cancer study, and one year in the basal cell carcinoma and oral leukoplakia studies. The breast cancer study started in March 1987, closing accrual on July 31, 1993. A total of 2,972 patients entered the study; 2,849 were evaluable (1,422 in the 4-HPR group and 1,427 in the control group). Of 2,849 evaluable patients, 867 completed the first five years, 1,142 are still ongoing, and 840 patients have interrupted the study for various reasons. Follow-up is ongoing. The basal cell carcinoma study started in January 1990. As of January 1994, a total of 786 patients had entered the study; 760 were evaluable (363 in the 4-HPR group and 367 in the control group). Of 760 patients in the study, 568 completed the first year, 62 are ongoing and 130 discontinued for various reasons. The study is ongoing. The oral leukoplakia study started in September 1988, closing accrual on February 1, 1994. A total of 174 patients entered the study; 170 were evaluable (84 in the 4-HPR group and 86 in the control group). The preliminary data of this study have been published. Updated results as of June 1994 were 11 recurrences and three new occurrences in the 4-HPR group; the control group also had 11 recurrences, as well as 12 new occurrences. Follow-up is ongoing.
    Additional Material: 3 Ill.
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  • 5
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Hydrochloric acid and hydrobromic acid react with α-mono- and α, α-disubstituted β-lactones under ring cleavage leading unequivocally to the corresponding α-mono- or α, α-disubstituted β-halogenopropionic acids. These products are interesting starting materials for the preparation of new compounds and can be reduced by zinc and formic acid to the corresponding propionic acids. The described synthesis is a general one and may be carried out with good yields. Moreover it has been observed that the new α, α-disubstituted β-halogenopropionic acids can be reconverted to the β-propiolactones by the action of alkalies or by zinc in neutral or slightly acidic medium.
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  • 6
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es werden Synthese, chemische und physikalisch-chemische Eigenschaften sowie IR.- und UV.-Spektren einer Keihe von 4-mono- und 4,4-disubstituierten 3-Pyrazolidinonen, welche zum Teil auch an den Stickstoffatomen 1 und/oder 2 substituiert sind, beschrieben. Die vorläufigen Ergebnisse der pharmakologischen Untersuchung werden mitgeteilt.
    Additional Material: 9 Ill.
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  • 7
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Durch Einwirkung von Thionylchlorid und Pyridin auf α,α-disubstituierte Malonsäurehalbamide ist eine Reihe am Stickstoffatom unsubstituierter Azetidin-2,4-dione (Malonimide) dargestellt worden. Als besonders interessant erweisen sich die unerwartete Säurebeständigkeit der neuen Verbindungen sowie ihre Reduktion mit Lithiumaluminiumhydrid zu 3,3-disubstituierten Azetidinen.
    Additional Material: 4 Tab.
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  • 8
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es wird über eine intramolekulare Umamidierung berichtet, welche in guter Ausbeute von den viergliedrigen 3,3-disubstituierten 1-(o-Aminophenyl)-azetidin-2-onen (V) durch Ringerweiterung zu den siebengliedrigen 3,3-disubstituierten 2,3,4,5-Tetrahydro-1H-(benzo[b]1,4-diazepin)-2-onen (VII) führt. Neben der Synthese wird über die chemischen und physikalisch-chemischen Eigenschaften dieser neuen Verbindungen, über deren IR.- und NMR.-Spektren sowie über einige ihrer Umsetzungen ausführlich berichtet. Der mutmassliche Mechanismus dieser Umlagerung wird diskutiert. Diese Synthese stellt zugleich den ersten allgemeinen Weg zur einfachen Darstellung der bis heute noch nicht beschriebenen 3,3-disubstituierten 2,3,4,5-Tetrahydro-1H-(benzo[b]1,4-diazepin)-2-one (VII) dar.
    Additional Material: 6 Ill.
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  • 9
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An 3.3-disubstituierten Azetidinen werden N-Acylierungsversuche mit Mono- und Dicarbonsäurechloriden sowie mit Säureanhydriden beschrieben. Dann wird über die Darstellung von N-Alkyl-Derivaten durch LiAlH4-Reduktion der entsprechenden Acylderivate sowie durch ein neues Verfahren (alkylierende Reduktion) berichtet. Die Einwirkung von Methyljodid auf 3.3-disubstituierte Azetidine sowie deren Umwandlung mittels Natriumcyanats und Salzsäure in N-Carbamoyl-Derivate wird beschrieben.
    Additional Material: 5 Tab.
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  • 10
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es wird über ein neues Herstellungsverfahren für verschiedene in α-Stellung substituierte β-Lactone berichtet. α-Substituierte β-Amino-propionsäuren werden bei niedriger Temperatur mit Natriumnitrit und Essigsäure diazotiert, wobei sich die β-Lactone als flüssige oder niedrigschmelzende Verbindungen ausscheiden. Die Eigenschaften dieser Verbindungen sowie ihre Umwandlung durch die Einwirkung von Hydrazinhydrat in die entsprechenden α-substitutierten β-Hydroxy-propionsäurehydrazide werden beschrieben.
    Additional Material: 5 Tab.
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