Foreign serum-induced pancreatitis in mice. II. Secretory disturbances of acinar cells

As previously reported, pancreatic acinar cell necrosis and inflammation develop in mice a few hours after one intraperitoneal injection of foreign serum. However, sublethally injured acinar cells exhibited notable increases in both zymogen granule numbers and amylase activity, observed within 3 hours and increasing with time. These two changes were coupled with a progressive decrease in the secretory response to pilocarpine and were preceded by significant disturbances in pancreatic tissue concentrations of sodium and potassium. We conclude that (1) the granule increase results from an induced disturbance of the granule exocytosis mechanism while granule formation continues and, therefore, (2) the granule secretory process is more sensitive to the serum injury mechanism than is the zymogen synthesis process. Although the granule increases developed in acinar cells throughout most of the nonnecrotic gland and persisted for at least 24 hours, acinar cell necrosis was maximal in extent--approximately 25% of the gland in severest form--by 12 to 15 hours. We conclude, therefore, that the increase in granules is neither the primary determinant nor initiator of acinar cell death. The latter is likely caused by disturbed plasma membrane functions, sufficient in some cells to result in lethal changes in ion and fluid composition. The injury mechanism, which permits granule formation to go on in the face of impaired granule exocytosis, is yet to be worked out. The possibilities are discussed in relationship to the reactivity of foreign sera for target cell plasma membranes.     

Low-Frequency Piezoelectric Energy Conversion for an Intrathoracic Artificial Heart

The present paper is concerned with an evaluation of a piezoelectric energy conversion system in which two columns of piezoelectric ceramic disks are excited axially by means of thin metallic shims stacked alternately with the disks. Mechanical energy output is extracted through the expansion and contraction of the Columns. The treatment is based upon the equivalent circuit approach first suggested by Mason. A lever system is used in making the mechanical impedance transformation between the very high force and small displacement of the piezoelectric columns and the low force and relatively large displacement required for an artificial heart. The role of mass loading in improving the power capability and efficiency of the energy converter is clearly indicated. It is concluded that the theoretical energy output per unit mass of material per cycle and the efficiency of conversion are such as to justify a continued developmental effort.     

An alternative to tandem mass spectrometry: isoelectric point and accurate mass for the identification of peptides

The traditional approach to the identification of peptides in complex biological samples integrally involves the use of tandem mass spectrometry to generate a unique fragmentation pattern in order to accurately assign its identity to a particular protein. In this article we describe the theoretical basis for a new paradigm for the identification of peptides and proteins. This methodology employs the use of accurate mass and peptide isoelectric point (pI) as identification criteria, and represents a change in focus from current tandem mass spectrometry-dominated approaches. A mathematical derivation of the false positive rate associated with accurate mass and pI measurements is presented to demonstrate the utility of the technique. The equations for calculation of the experimental false positive rate allow for the determination of the validity of the data. The false positive rate issue examined in detail here is not restricted to accurate mass-based approaches, but also has application to the tandem mass spectrometry community as well. The theoretical proteomes of Escherichia coli and Rattus norvegicus are used to evaluate the efficacy of this approach. The power of the technique is demonstrated by analyzing a series of peptides with the same monoisotopic masses but with differing isoelectric points. Finally, the speed of algorithm when combined with the experimental peptide analysis has the potential to rapidly accelerate the protein identification process.     

On-site treatment of a motorway service area wastewater using a package sequencing batch reactor (SBR).

A sequencing batch reactor (SBR) treating the effluent of a motorway service station in the south of England situated on a major tourist route was investigated. Wastewater from the kitchens, toilets and washrooms facilities was collected from the areas on each side of the motorway for treatment on-site. The SBR was designed for a population equivalent (p.e.) of 500, assuming an average flow of 100 m3/d, influent biochemical oxygen demand (BOD) of 300 mg/l, and influent suspended solids (SS) of 300 mg/l. Influent monitoring over 8 weeks revealed that the average flow was only 65 m3/d and the average influent BOD and SS were 480 mg/l and 473 mg/l respectively. This corresponded to a high sludge loading rate (F:M) of 0.42 d(-1) which accounted for poor performance. Therefore the cycle times were extended from 6 h to 7 h and effluent BOD improved from 79 to 27 mg/l.     

The alpha subunit of toluene dioxygenase from Pseudomonas putida F1 can accept electrons from reduced FerredoxinTOL but is catalytically inactive in the absence of the beta subunit

The oxygenase component of toluene dioxygenase from Pseudomonas putida F1 is an iron-sulfur protein (ISPTOL) consisting of alpha (TodC1) and beta (TodC2) subunits. Purified TodC1 gave absorbance and electron paramagnetic resonance spectra identical to those given by purified ISPTOL. TodC1 was reduced by NADH and catalytic amounts of ReductaseTOL and FerredoxinTOL. Reduced TodC1 did not oxidize toluene, and catalysis was strictly dependent on the presence of purified TodC2.     

Software for chemical and extractive metallurgy

A dramatic software migration has occurred from mainframe to microcomputer since the first conference in this biennial series was held in 1985, and this migration will continue. Two major observations may be made—there is a lack of critically evaluated thermodynamic data, especially for solution models, and there is a continuing need for accurate thermodynamic property measurements to be utilized by the current and next generation of increasingly powerful and unique thermodynamic packages. The authors encourage researchers working on the development of solution phase models and solution databases to consider the format of this data so it can readily be incorporated into thermodynamic software.     

The stability of α-Sn grown on CdTe by molecular beam epitaxy

We have examined the effect of the substrate orientation, thickness, growth rate, substrate temperature and inclusion of small amounts of Ge on the transition temperature of α-Sn films grown on CdTe. The transition temperature from α-Sn to β-Sn was determined by optical microscopy to be as high as 132° C. CdTe(ll0) is a somewhat better orientation than CdTe(100), and CdTe(lll)B appears to be totally unacceptable. The transition temperature from α-Sn to β-Sn depends on the film thickness; thinner films have a somewhat higher transition temperature than thicker films. The film quality can be increased by lowering the growth rate and raising the growth temperature to about 75° C. Since the transition from α-Sn to β-Sn starts at defects in the film, improving the film quality by lowering the growth rate and raising the growth temperature raises the transition temperature. Also by adding small amounts of Ge (∼2%) the transition temperature of films grown on CdTe can be significantly increased.     

T helper 2-dominant antilymphoma immune response is associated with fatal outcome

The precise role of the endogenous immune system in modulating cancer development remains unclear. Tumor cells are generally thought to be nonimmunogenic because they are of 'self' origin. However, tumor-reactive lymphocytes can be isolated from patients with many types of cancer. It is unclear what role these lymphocytes play and why they fail to protect the host. Using a murine B-cell leukemia/lymphoma (BCL1) model, we showed the development of a vigorous antitumor T-cell response in the tumor-susceptible host. Specific T-cell responses against BCL1 developed as early as day 4. However, the nature of this nonprotective response is different from the protective response produced in a major histocompatibility complex-matched tumor-resistant host. Susceptible hosts developed a T helper 2 (Th2)-dominant response, whereas resistant hosts developed a Th1-dominant response to BCL1. Cytolytic activity against BCL1 developed in both resistant and susceptible hosts, but in the susceptible host, this response was weaker and delayed compared with that in the resistant host. Thus, tumor susceptibility does not necessarily mean the absence of an antitumor immune response. Rather, the nature of the antitumor immune response is critical in determining clinical outcome.     

Molecular dissection of native mammalian forebrain NMDA receptors containing the NR1 C2 exon: direct demonstration of NMDA receptors comprising NR1, NR2A, and NR2B subunits within the same complex

The subunit compositions of the NR1 C2 exon-containing N-methyl-D-aspartate (NMDA) receptors of adult mammalian forebrain were determined by using a combination of immunoaffinity chromatography and immunoprecipitation studies with NMDA receptor subunit-specific antibodies. NMDA receptors were solubilised by sodium deoxycholate, pH 9, and purified by anti-NR1 C2 antibody affinity chromatography. The purified receptor subpopulation showed immunoreactivity with anti-NR1 C2, anti-NR1 N1, anti-NR1 C2', anti-NR2A, and anti-NR2B NMDA receptor antibodies. The NR1 C2-receptor subpopulation was subjected to immunoprecipitation using anti-NR2B antibodies and the resultant immune pellets analysed by immunoblotting where anti-NR1 C2, anti-NR1 C2', anti-NR2A, and anti-NR2B immunoreactivities were all found. Quantification of the immunoblots showed that 46% of the NR1 C2 immunoreactivity was associated with the NR2B subunit. Of this, 87% (i.e., 40% of total) were NR1 C2/NR2B receptors and 13% (6% of total) were NR1 C2/NR2A/NR2B, thus identifying the triple combination as a minor receptor subset. These results demonstrate directly, for the first time, the coexistence of the NR2A and NR2B subunits in native NMDA receptors. They show the coexistence of two splice forms of the NR1 subunit, i.e., NR1 C2 and NR1 C2', in native receptors and, in addition, they imply an NMDA receptor subpopulation containing four types of NMDA receptor subunit, NR1 C2, NR1 C2', NR2A, and NR2B, which, in accord with molecular size determinations, predicts that the NMDA receptor is at least tetrameric. These results are the first quantitative study of NMDA receptor subtypes and demonstrate molecular heterogeneity for both the NR1 and the NR2 subunits in native forebrain NMDA receptors.