Comments on `A practical end-of-life model for semiconductordevices' [and reply]

Several observations are made on the above-named work by M.S. Ash and H.C. Gorton (see ibid., vol.38, no.4, p.485-93, Oct. 1989) concerning gradual performance deterioration in semiconductor devices. The commenter suggests that the development of predictive tools for reliability assessments involving long-term deterioration in such devices requires that careful attention be paid to the operational physics of the device, including temperature-dependent characteristics. An author's reply is included     

Effects of bovine somatotropin on dry matter intake, milk yield and body temperature in Holstein and Jersey cows during heat stress

Thirty-one lactating Holstein and Jersey cows were used to determine the effect of daily injections of 0 or 20 mg of recombinant bST in hot, humid weather. The comparison period lasted 80 d, from mid-June through August. The maximum and minimum ambient temperature and relative humidity averaged 34.6 and 22.2 degrees C and 100 and 59.8%, respectively. Body temperatures of somatotropin-treated Holsteins were elevated over controls by .2 and .3 degrees C at the a.m. and p.m. milkings, respectively, whereas corresponding treatment effects for Jerseys were .5 and .6 degrees C, thus demonstrating a breed by treatment interaction. The response of milk and FCM yields and apparent efficiency of production to somatotropin administration depended on the level of production prior to treatment. Cows at low pretreatment production increased milk and FCM yields to a greater degree than did cows at higher production. A breed by treatment interaction showed that Holsteins increased milk and FCM yields more than Jerseys upon administration of somatotropin. Intake of DM was not affected by treatment. Cows administered bST lost BW and condition score. Greater heat stress was associated with the higher milk production of cows administered bST.     

Riboflavin-mediated delivery of a macromolecule into cultured human cells

The effects of perivascular nerve stimulation and phenylephrine on osmolyte release were studied in the intact perfused rat liver and isolated liver parenchymal cells (PC) and nonparenchymal cells. In the perfused liver, electrical stimulation of perivascular nerves (20 Hz/2 ms/20 V) led to a phentolamine-sensitive increase of cell hydration by 6.5% +/- 1.2% (n = 3) and a transient phentolamine-sensitive stimulation of taurine and inositol, but not betaine, release. These nerve effects were mimicked by phenylephrine, but not prostaglandin F2alpha, and were not affected by sodium nitroprusside (SNP) or ibuprofen. Nerve stimulation-induced taurine, but not inositol, release was inhibited by 4, 4'-di-isothiocyanatostilbene-2,2'-disulphonic acid (DIDS) (50 micromol/L). Single-cell fluorescence studies with isolated liver PC, Kupffer cells (KC), sinusoidal endothelial cells (SEC), and hepatic stellate cells (HSC) revealed that phenylephrine induced an increase in cytosolic free Ca2+ only in PC and HSC, but not in KC and SEC, whereas extracellular uridine triphosphate (UTP) produced Ca2+ transients/oscillations in all liver cell types studied. Phenylephrine had no effect on osmolyte release from isolated KC and SEC, but increased taurine (but not inositol) release from PC and inositol (but not taurine) efflux from HSC. The data suggest that: 1) liver cell hydration and-consecutively-osmolyte content are modulated by hepatic nerves via an alpha-adrenergic mechanism, which does not involve eicosanoids or hemodynamic changes; 2) that PC and HSC are the primary targets for nerve-dependent alpha-adrenergic activation, whereas 3) KC and SEC probably do not express alpha-adrenoceptors coupled to Ca2+ mobilization or osmolyte efflux.     

Developing a culture of lifelong learning in a library environment

Between 1995 and 1996, the Annette and Irwin Eskind Biomedical Library (EBL) at Vanderbilt University Medical Center (VUMC) radically revised the model of service it provides to the VUMC community. An in-depth training program was developed for librarians, who began to migrate to clinical settings and establish clinical librarianship and information brokerage services beyond the library's walls. To ensure that excellent service would continue within the library, EBL's training program was adapted for library assistants, providing them with access to information about a wide variety of work roles and processes over a four to eight-month training period. Concurrently, customer service areas were reorganized so that any question--whether reference or circulation--could be answered at any of four service points, eliminating the practice of passing customers from person to person between the reference and circulation desks. To provide an incentive for highly trained library assistants to remain at EBL, management and library assistants worked together to redesign the career pathway based on defined stages of achievement, self-directed participation in library-wide projects, and demonstrated commitment to lifelong learning. Education and training were the fundamental principles at the center of all this activity.     

Conversion of 3-chlorocatechol by various catechol 2,3-dioxygenases and sequence analysis of the chlorocatechol dioxygenase region of Pseudomonas putida GJ31

Pseudomonas putida GJ31 contains an unusual catechol 2,3-dioxygenase that converts 3-chlorocatechol and 3-methylcatechol, which enables the organism to use both chloroaromatics and methylaromatics for growth. A 3.1-kb region of genomic DNA of strain GJ31 containing the gene for this chlorocatechol 2,3-dioxygenase (cbzE) was cloned and sequenced. The cbzE gene appeared to be plasmid localized and was found in a region that also harbors genes encoding a transposase, a ferredoxin that was homologous to XylT, an open reading frame with similarity to a protein of a meta-cleavage pathway with unknown function, and a 2-hydroxymuconic semialdehyde dehydrogenase. CbzE was most similar to catechol 2,3-dioxygenases of the 2.C subfamily of type 1 extradiol dioxygenases (L. D. Eltis and J. T. Bolin, J. Bacteriol. 178:5930-5937, 1996). The substrate range and turnover capacity with 3-chlorocatechol were determined for CbzE and four related catechol 2,3-dioxygenases. The results showed that CbzE was the only enzyme that could productively convert 3-chlorocatechol. Besides, CbzE was less susceptible to inactivation by methylated catechols. Hybrid enzymes that were made of CzbE and the catechol 2, 3-dioxygenase of P. putida UCC2 (TdnC) showed that the resistance of CbzE to suicide inactivation and its substrate specificity were mainly determined by the C-terminal region of the protein.     

Intestine-Specific, Oral Delivery of Captopril/Montmorillonite: Formulation and Release Kinetics

The intercalation of captopril (CP) into the interlayers of montmorillonite (MMT) affords an intestine-selective drug delivery system that has a captopril-loading capacity of up to ca. 14 %w/w and which exhibits near-zero-order release kinetics.