Identification and characterization of human rhinovirus-14 3C protease deamidation isoform

A purified recombinant human rhinovirus-14 3C protease preparation contained only approximately 50% active enzyme as titrated using specifically designed irreversible 3C protease inhibitors. Analysis of the purified 3C protein by isoelectric focusing showed differently charged 3C isoforms that had isoelectric points (pI) of 8.3 (55%) and 9.0 (45%), with the latter one being consistent with the predicted pI of the human rhinovirus-14 3C protein. Further analysis indicated that the pI 8.3 protein was the deamidated form of 3C, and it displayed approximately 10-fold reduced cleavage activity relative to the original 3C protease sample. Peptide mapping followed by sequence analysis revealed that a single asparagine, Asn-164, was deamidated to aspartic acid in the pI 8.3 isoform. Converting Asn-164 to Asp by site-directed mutagenesis resulted in a mutated 3C protease with extremely low activity, as seen with the pI 8.3 isoform, indicating a role of Asn-164 in substrate recognition and binding. In addition, the deamidated 3C protease was found to be present in vivo, and its abundance was related to the viral replication cycle. Moreover, mutant virus carrying Asp-164 showed reduced viability in infected cells. Taken together, our data suggest that 3C protein deamidation plays a role in the regulation of its enzymatic activity.

Rapid detection of Listeria monocytogenes by a PCR assay specific for an aminopeptidase

Specific and rapid detection of Listeria monocytogenes is very important with regard to food safety since all other species of Listeria appear to be non-pathogenic to humans. Conventional microbiological detection methods are very time consuming. The polymerase chain reaction (PCR) is one of the most promising techniques for rapid detection of micro-organisms in food products. We have developed a PCR assay, specific for L. monocytogenes, based on the gene encoding an aminopeptidase, which previously has not been described for this species. The L. monocytogenes aminopeptidase shares strong sequence similarity with aminopeptidase C from Streptococcus thermophilous, Lactobacillus lactis, Lactobacillus helveticus, and with a cysteine proteinase from Saccharomyces cerevisiae. Polymerase chain reaction primers were synthesized based on the DNA sequence of the aminopeptidase gene. A 90 bp product was apparent with all L. monocytogenes strains tested but not with other species of Listeria or other bacterial genera. The PCR assay, which is performed directly from whole bacterial cells, does not involve DNA purification and can be conducted in 4 h. It provided positive identification of L. monocytogenes in mixed culture.

Purification, amino acid sequence and mode of action of bifidocin B produced by Bifidobacterium bifidum NCFB 1454

Bifidocin B produced by Bifidobacterium bifidum NCFB 1454 was purified to homogeneity by a rapid and simple three step purification procedure which included freeze drying, Micro-Cel adsorption/desorption and cation exchange chromatography. The purification resulted in 18% recovery and an approximately 1900-fold increase in the specific activity and purity of bifidocin B. Treatment with bifidocin B caused sensitive cells to lose high amounts of intracellular K+ ions and u.v.-absorbing materials, and to become more permeable to ONPG. Bifidocin B adsorbed to the Gram-positive bacteria but not the Gram-negative bacteria tested. Its adsorption was pH-dependent but not time-dependent. For sensitive cells, the adsorption and lethal action of bifidocin B was very rapid. In 5 min, 95% of bifidocin B adsorbed onto sensitive cells. Several salts inhibited the binding of bifidocin B, which could be overcome by increasing the amount of bifidocin B added. Pre-treatment of sensitive cells and cell walls with detergents, organic solvents or enzymes did not cause a reduction in subsequent cellular binding of bifidocin B, but cell wall preparations treated with methanol:chloroform and hot 20% (w/v) TCA lost the ability to adsorb bifidocin B. Also, the addition of purified heterologous lipoteichoic acid to sensitive cells completely blocked the adsorption of bifidocin B. The amino acid sequence indicated that the bacteriocin contained 36 residues. N-terminal amino acid sequence analysis yielded a sequence of KYYGNGVTCGLHDCRVDRGKATCGIINNGGMWGDIG. Curing experiments with 20 micrograms ml-1 acriflavine yielded cell derivatives that no longer produced bifidocin B but retained immunity to bifidocin B. Production of bifidocin B, but not immunity to bifidocin B, was associated with a plasmid of about 8 kb in this strain.

Reactivities of genus-specific monoclonal antibody EM-6E11 against Listeria species and serotypes of Listeria monocytogenes grown in nonselective and selective enrichment broth media

Depending on the growth medium used for enrichment of bacterial cells prior to assay, the monoclonal antibody (MAb) EM-6E11 recognizing Listeria genus-specific epitope on 43 and 94 to 97 kDa cell-surface antigens (A. K. Bhunia and M. G. Johnson, Appl. Environ. Microbiol. 58:1924-1929, 1992) exhibited extensive variability in the detection of Listeria species. MAb EM-6E11 strongly detected live cells of all Listeria species and all serotypes of L. monocytogenes by ELISA when cells were grown in nonselective brain heart infusion (BHI) broth, in selective Listeria enrichment broth (LEB), or in Listeria repair broth (LRB). In contrast, EM-6E11 detected only four of the thirteen serotypes of L. monocytogenes (serotypes 1/2c, 3b, 4ab, and 7) when cells were grown in the UVM1 formulation of Listeria enrichment broth (UVM1) or Fraser broth (FRB). This MAb failed to react with live cells of four other Listeria species, including L. ivanovii, L. welshimeri, L. grayi, and L. murrayi cells grown in UVM1 or FRB. Heating of Listeria cells at 100 degrees C for 20 min, irrespective of the enrichment media used, led to large losses of MAb EM-6E11 reactivity in ELISA, suggesting that the specific cell-surface epitopes involved may not be heat stable. Our results confirm that MAb EM-6E11 is suitable for detection of live cells but not heat-killed cells of Listeria spp. and can be used in conjunction with an enrichment step in BHI, LEB, or LRB but not in UVM1 or FRB.

Unstable expression and thermal instability of a species-specific cell surface epitope associated with a 66-kilodalton antigen recognized by monoclonal antibody EM-7G1 within serotypes of Listeria monocytogenes grown in nonselective and selective broths

Conditions that resulted in unstable expression and heat instability of a cell surface epitope associated with a 66-kDa antigen in Listeria monocytogenes serotypes were identified with the probe monoclonal antibody (MAb) EM-7G1 in an enzyme-linked immunosorbent assay. This epitope appeared to be absent in three serotypes (serotypes 3b, 4a, and 4c), which did not react with MAb EM-7G1 irrespective of the enrichment broth tested. The remaining 10 serotypes were detected by MAb EM-7G1 only when cells were grown in nonselective brain heart infusion broth (BHI) or selective Listeria enrichment broth (LEB). When cells were grown in Listeria repair broth (LRB), only 6 of the 13 serotypes were detected by MAb EM-7G1, and recognition of serogroup 4 was completely lost. None of the 13 serotypes was detected by MAb EM-7G1 when cells were grown in two other commonly used Listeria-selective media, UVM1 broth and Fraser broth (FRB), indicating that possible loss of epitope expression occurred under these conditions. MAb EM-7G1 maintained species specificity without cross-reacting with live or heat-killed cells of six other Listeria spp. (Listeria ivanovii, Listeria innocua, Listeria seeligeri, Listeria welshimeri, Listeria grayi, and Listeria murrayi) irrespective of the enrichment conditions tested. Due to heat instability of the cell surface epitope when it was exposed to 80 or 100 degrees C for 20 min, MAb EM-7G1 is suitable for detection of live cells of L. monocytogenes in BHI or LEB but not in LRB, UVM1, or FRB enrichment medium.

Detection and characterization of a bacteriocin produced by Lactococcus lactis subsp. cremoris R isolated from radish

Bacteria isolated from radish were identified as Lactococcus lactis subsp. cremoris R and their bacteriocin was designated lactococcin R. Lactococcin R was sensitive to some proteolytic enzymes (proteinase-K, pronase-E, proteases, pepsin, alpha-chymotrypsin) but was resistant to trypsin, papain, catalase, lysozyme and lipase, organic solvents, or heating at 90 degrees C for 15, 30 and 60 min, or 121 degrees C for 15 min. Lactococcin R remained active after storage at -20 and -70 degrees C for 3 months and after exposure to a pH of 2-9. The molecular weight of lactococcin R was about 2.5 kDa. Lactococcin R was active against many food-borne pathogenic and food spoilage bacteria such as Clostridium, Staphylococcus, Listeria, Bacillus, Micrococcus, Enterococcus, Lactobacillus, Leuconostoc, Streptococcus and Pediococcus spp., but was not active against any Gram-negative bacteria. Lactococcin R was produced during log phase and reached a maximum activity (1600 AU ml-1) at early stationary phase. The highest lactococcin R production was obtained in MRS broth with 0.5% glucose, at 6.5-7.0 initial pH values, 30 degrees C temperature and 18-24-h incubation times. Lactococcin R adsorbed maximally to its heat-killed producing cells at pH 6-7 (95%). Crude lactococcin R at 1280 AU ml-1 was bactericidal, reducing colony counts of Listeria monocytogenes by 99.98% in 3 h. Lactococcin R should be useful as a biopreservative to prevent growth of food-borne pathogenic and food spoilage bacteria in ready-to-eat, dairy, meat, poultry and other food products. Lactococcin R differs from nisin in having a lower molecular weight, 2.5 kDa vs 3.4 kDa, and in being sensitive to pepsin and alpha-chymotrypsin to which nisin is resistant.

Characterization and antimicrobial spectrum of bifidocin B, a bacteriocin produced by Bifidobacterium bifidum NCFB 1454

Five stains of Bifidobacterium bifidum (ATCC 11863 and 29591, and NCFB 1453, 1454, 1455) were examined for production of bacteriocins in MRS broth with 0.05% cysteine. Only strain NCFB 1454 excreted a bacteriocin into the broth: it was designated bifidocin B. Bifidocin B was sensitive to several proteolytic enzymes (protease IV, pronase E, protease XVII, proteinase K, trypsin, alpha-chymotrypsin, papain, and pepsin), but was resistant to catalase, peroxidase, lipase, lysozyme, cellulase, ribonuclease A, and amylases. It was also resistant to organic solvents such as ethyl alcohol, acetone, hexane, chloroform, methanol, and ether, and to heating at 90 degrees C for 15, 30, and 60 min or at 121 degrees C for 15 min. Bifidocin B remained active after storage at -20 or -7 degrees C for 3 months and retained biological activity after exposure to pH values of 2 to 10. Bifidocin B was active against some food-borne pathogens and food spoilage bacteria such as Listeria, Enterococcus, Bacillus, Lactobacillus, Leuconostoc, and Pediococcus species but was not active against the other gram-positive and gram-negative bacteria tested. Bifidocin B was produced during exponential phase, reaching a maximum activity of 3,200 AU/ml at early stationary phase. Bifidocin B had a molecular mass of about 3.3 kDa as analyzed by Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

Antitumor agents--CLXVII. Synthesis and structure-activity correlations of the cytotoxic anthraquinone 1,4-bis-(2,3-epoxypropylamino)-9,10-anthracenedione, and of related compounds

1,4-Bis-(2,3-epoxypropylamino)-9,10-anthracenedione (3) was synthesized in this laboratory and was found to be a potent antitumor agent. Derivatives of this compound containing anthraquinone, naphthoquinone, and quinone skeletons were also prepared and evaluated for in vitro cytotoxic activity in several cell lines. These molecules were designed as bifunctional antitumor agents with the potential to act as (1) intercalating agents due to their planar backbones, and (2) alkylating agents due to the presence of alkylating moieties in their side chains. Compounds with an anthraquinone skeleton and propylamino side chains containing epoxides or halohydrins as the alkylating species showed greater activity than similar compounds with naphthoquinone or quinone skeletons. Compounds without these alkylating functionalities (e.g., with alkene or amino groups) were generally inactive. Hydroxy substitution on the planar skeleton in conjunction with alkylating side chains gave compounds with the most potent cytotoxic activity. The position of the hydroxy groups and side chains could be varied without substantially affecting activity. Activity was retained when an epoxypropyloxy side chain was substituted for the epoxypropylamino side chain in the parent compound.

Synthesis and biological activity of novel nonsteroidal progesterone receptor antagonists based on cyclocymopol monomethyl ether

A novel class of nonsteroidal progesterone receptor antagonists has been synthesized and was shown to exhibit moderate binding affinity for hPR-A, the ability to inhibit the transcriptional activity of human progesterone receptor (hPR) in cell-based assays, and anti-progestational activity in a murine model. Cyclocymopol monomethyl ether, a component of the marine alga Cymopolia barbata was weakly active in random screening against PR. Investigations into the SAR surrounding the core of this natural product lead structure resulted in improved in vitro activity. In contrast to the cross-reactivity profiles observed with known steroidal antiprogestins, compounds of the general structural class described display a high degree of selectivity for the progesterone receptor and no functional activity on the glucocorticoid receptor.

Discovery of novel intracellular receptor modulating drugs

Utilizing the co-transfection assay as a guide to determining structure activity relationships, we have been pursuing the discovery of non-steroidal hPR modulators. Small molecule, non-steroidal lead structures have been identified. Optimization of these structures has yielded more potent hPR modulators. Improved cross-reactivity profiles with other intracellular receptors are a feature of these compounds owing to their non-steroidal nature.

Frozen stored murine hybridoma cells can be used to determine the virulence of Listeria monocytogenes

Murine hybridoma cells, designated Ped-2E9, when stored up to 60 days at -196 degrees C or up to 48 days at -80 degrees C, gave results equivalent to those for freshly grown murine hybridoma cells in an in vitro pathogenicity assay of Listeria species. Thus, laboratories do not need to have their own tissue culture facilities to maintain the hybridoma cells for the assay described.

Simple, rapid and sensitive high-performance liquid chromatographic determination of delavirdine and its N-desisopropyl metabolite in human plasma

A method for the determination of a bisheteroarylpiperazine, non-nucleoside HIV-1 reverse transcriptase inhibitor, delavirdine, and its N-desisopropyl metabolite in human plasma, is described. Samples were deproteinized by addition of two parts of a solution of internal standard in acetonitrile (1 microgram/ml) to one part plasma. The supernatant was diluted with 10 mM phosphate buffer, pH 6.0, and injected onto the HPLC system. Fluorescence of the eluent was monitored with excitation at 302 nm and emission at 425 nm. Quantitation of delavirdine and its metabolite was achieved by comparing the peak-height ratio of each component relative to the internal standard to a through-the-origin linear regression curve determined from fortified plasma calibration standards. The assay was linear over the concentration range 0.02-17 microM for both delavirdine and its metabolite. The precision of the method, as expressed by the mean C.V. of the back-calculated, non-zero, standard concentrations, was +/- 4.4% for delavirdine and +/- 4.3% for the metabolite. The assay has been validated and utilized to analyze samples from human and animal pharmacokinetic studies.

Enzymatic synthesis of milligram quantities of ribozymes in small volumes

Milligram quantities of ribozymes (Rzs) can be synthesized in vitro in reaction volumes of 1 mL or less using AmpliScribe T7 RNA polymerase kits to transcribe either linear plasmids or oligodeoxynucleotide templates. Model hammerhead Rzs were synthesized that specifically cleave RNA-encoding chloramphenicol acetyl transferase sequences. Methods are presented for the transcription of Rzs of virtually any length and sequence composition at a fraction of the cost of chemical synthesis.

Protein binding of tirilazad (U-74006) in human, Sprague-Dawley rat, beagle dog and cynomolgus monkey serum

Determination of the serum protein binding of tirilazad across species was required to predict the pharmacokinetic behavior of this new drug. Equilibrium dialysis and ultrafiltration techniques, commonly used to study serum protein binding, were shown to be unsuitable for tirilazad due to high nonspecific binding and low aqueous solubility, resulting in unbound drug levels that were nondetectable with current analytical methodology. Ultracentrifugation appeared to offer a technique with which unbound tirilazad could be measured; however, after extensive studies, the apparent lipid partitioning behavior of tirilazad into low density and very low density lipoproteins showed that ultracentrifugation was also unsuitable for determination of the true unbound fraction of tirilazad. Fractions of tirilazad measured in the supernatant were highly correlated with total triglycerides and very low density lipoproteins in the sera of all species analyzed. Studies with delipidized human serum yielded a nonsaturable binding isotherm with free fractions of less than 0.6 +/- 0.02% (mean +/- S.D.) over a concentration range of 4.6 to 55.6 micrograms/ml (normal human in vivo range, 0.01-20 micrograms/ml). These data indicated that, as the triglyceride content of the sera increases, portions of tirilazad bound to serum proteins shift into the lipid phase of lipoproteins. What effect this has on the true unbound fraction is unknown and does not seem to be ascertainable with current technology.

Osteonectin/SPARC is a product of articular chondrocytes/cartilage and is regulated by cytokines and growth factors

Rabbit articular chondrocytes maintained in monolayer, synthesized and secreted a 46 kDa protein into the culture medium. N-terminal sequence analysis and immunoprecipitation of the radiolabeled material revealed this protein to be osteonectin (ON)/SPARC, a protein previously shown to be present in bone. When chondrocytes were exposed to interleukin-1, a cytokine with matrix degradative properties, ON synthesis and secretion was greatly inhibited. However, this was specific to IL-1 since two other pro-inflammatory cytokines (tumor-necrosis factor-alpha and interleukin-6) with properties similar to IL-1, failed to cause any discernible effect on ON synthesis. Several growth factors (TGF-beta, PDGF, and IGF-1), that have been shown to stimulate other cartilage matrix macromolecular synthesis, also stimulated ON synthesis and were also able to reverse the inhibitory effect of IL-1 on ON synthesis. These observations were also demonstrated in explant cultures of cartilage. Our studies suggest that ON is a biosynthetic product of articular cartilage and could play a role in cartilage structure and/or function.

A six-hour in vitro virulence assay for Listeria monocytogenes using myeloma and hybridoma cells from murine and human sources

An in vitro cell culture assay using myeloma cells and hybrid lymphocytes was developed which detected pathogenic Listeria strains in just 6 h. Three separate hybridoma cell lines, murine Ped-2E9 and EM-7G1 and human RI.37 and murine myeloma NS1 cells, proved equally sensitive in responding to virulent Listeria species. Listeria monocytogenes along with other Listeria spp., collected from food and clinical sources, were inoculated at 10(8) cfu/ml into a suspension of Ped-2E9 (10(6)/ml). Pathogenic Listeria spp. killed 80% of hybridoma cells by 4 h, as determined by trypan blue exclusion test. Conversely, none of all nonpathogenic Listeria spp. killed the hybridoma cells. Ped-2E9 cells exposed to three strains of L. monocytogenes strains showed 96-97.5% death in 6 h measured by trypan blue staining and release of 91-97% of lactate dehydrogenase (LDH) enzyme. RI.37 cells showed similar results. A multiplicity of exposure (MOE) of 100 L. monocytogenes to 1 hybridoma cell or of 10:1 killed about 80% of the hybridoma cells in 4 or 6 h respectively. The in vitro virulence assay of L. monocytogenes with hybridoma cells compared favorably with the immunocompromised mouse model, yielding results in 6 h instead of 3 days. Intracellular L. monocytogenes and L. innocua were not recovered from Ped-2E9 hybridoma cells after 2 or 4 h of exposure. However, attachment of both L. monocytogenes and L. innocua cells on Ped-2E9 cell surfaces were observed under epifluorescence microscopy. Direct contact of hemolysin positive L. monocytogenes with hybridoma cells is essential to cause death, since hybridoma cells were not killed when they were separated from the growing bacteria by a 0.45 microns filter.

History of anthropogenic activities in Hamilton Harbour as determined from the sedimentary record

Bottom sediment cores collected from two closely spaced locations in the depositional basin of Hamilton Harbour (Lake Ontario, Canada) were analyzed for organic matter, bulk density, heavy metals and phosphorus concentrations. Combined data on dredging and steel production records in relation to core composition, together with (210)Pb dating were used to develop core chronology. Identification and enumeration of chironomid taxa and molluscs in both cores were carried out to interpret the paleoenvironmental conditions in the harbour. Chemical, geochronological and paleolimnological profiles of investigated cores indicate perturbation of the natural sedimentation processes by dredging and spoil disposal, with definite evidence of an infill of extrinsic littoral sediments. Decreasing metal concentrations in sediments reflect a positive response of sediments to decreased metal loadings to the harbour. The recent sediment accumulation rates, estimated from the (210)Pb profiles of the two cores, are 38 and 97 mg cm(-2) year(-1). Mass sedimentation rates of the pre-dredging era were higher (189 and 142 mg cm(-2) year(-1)) due to intensive harbour activities, municipal development and intensive crop production in the late 1800s.

Effective monitoring of pollution by toxic trace elements in waters, sediment and biota of the Derwent River Estuary, Tasmania, through long-term retention of analytical facilities

This study considers the effectiveness of the monitoring of toxic trace elements in various media from a polluted river estuary over a period of 15 years, using the same analytical techniques, facilities and, in some cases, the same operators. It shows that reliable comparisons can be made for monitoring waters, sediment and biota from the Derwent River Estuary between 1975 data and that from 1990. Rigorous studies were undertaken before and during 1975 to ensure that reliable data was achieved at that time. Such studies are reviewed and included the evaluation of digestion techniques for a range of heavy metals, specific attention to the reliability of mercury determination in sediments between laboratories, a comparison of direct calibration and standard addition techniques for metals in seawater, recoveries of an organomercury compound from fish, and sources of error arising from sample preparation of biota for subsequent metal analysis. Comparative results for standard reference materials in both 1975 and 1990 show good agreement and are considered reliable except for lead at low concentrations. The long-term retention of the analytical facilities permits a direct comparison of data from 2 monitoring programmes over the space of 15 years.

Development of PCR method specific for Marek's disease virus

A rapid polymerase chain reaction (PCR) assay specific for Marek's Disease Virus (MDV) was developed. This assay was able to detect MDV in inoculated chick kidney cells at dilutions of 10(-5). Negative PCR results were obtained using uninoculated chick cells, Marek's Disease Vaccine (SB), Herpesvirus of Turkeys (HVT) and Fowl Laryngotracheitis Vaccine (LT). Bursae, feathers and kidneys from MDV infected chickens were positive in the PCR assay. The same tissues from normal chickens were negative. This method required only 0.5 h for sample preparatory, 3 h for PCR application and 1 h for electrophoresis. Internal probe hybridization confirmed that the PCR products are from MDV, but this hybridization will not be necessary for future MDV detection.

A 16S rRNA-based DNA probe and PCR method specific for Listeria ivanovii

A 16S rRNA-based DNA probe and polymerase chain reaction (PCR) method was developed for identification and rapid detection of Listeria ivanovii. The probe (R-1) is 5'-GTAGTGACGCATGTCATCAC-3' corresponding to positions 185-204 in the L. ivanovii 16S rRNA sequence. DNA hybridization results indicated that R-1 probe only reacted with L. ivanovii, and not with six other species of Listeria or other bacteria tested. The PCR method using R-1 and a reverse primer, R-2, was positive with all eight strains of L. ivanovii tested but was negative with six other species of Listeria, including nine strains of L. monocytogenes, and 20 other taxonomically related bacteria tested. In our PCR method, starting with whole bacterial cells, only 3 h were required for the PCR assay and 1 h for electrophoresis without any additional time for DNA isolation and DNA hybridization. This PCR method detected as few as 4 cells of L. ivanovii in pure cultures and 4-40 cells of L. ivanovii in inoculated and diluted mouse feed, blood, or faeces samples.

Novel non-cross resistant diaminoanthraquinones as potential chemotherapeutic agents

A novel series of diaminoanthraquinones was discovered initially as protein kinase C inhibitors with IC50s in the 50-100 microM range. They exhibited potent tumor cell growth inhibitory activity in vitro without cross resistance to adriamycin. Further evaluation of two of the most active compounds NSC 639365 (3) and NSC 639366 (4) in human tumor cloning assay showed potent cytocidal activity. The results suggest therapeutical potentials against human tumors.

16S rRNA-based probes and polymerase chain reaction method to detect Listeria monocytogenes cells added to foods

A rapid polymerase chain reaction (PCR) method was developed for detection of Listeria monocytogenes in foods. This method used a pair of primers based on a unique region in the 16S rRNA sequence of L. monocytogenes, which were previously reported by us to yield a specific nucleic acid probe. Our method included use of a shorter denaturing time, a shorter annealing time, a rapid transition, and an increase in the number of cycles, resulting in good sensitivity. Just 3 h for PCR plus 1 h for electrophoresis was required. Additional time for DNA isolation and DNA hybridization was not needed. This method detected as few as 2 to 20 CFU of L. monocytogenes in pure cultures and as few as 4 to 40 CFU of L. monocytogenes in inoculated (10(8) CFU), diluted food samples. Seven of eight foods, including four poultry products, gave positive results. Only one food sample, soft cheese, gave interference. An internal probe hybridization test was used to confirm that the PCR products were from L. monocytogenes. A specificity test indicated that this PCR method was positive for all 13 strains of L. monocytogenes tested but negative for the other 6 species of Listeria, including 6 strains of L. innocua, and negative for 17 other gram-positive and gram-negative bacteria tested.

Identification of 5,6-dimethylbenzimidazole as the Co alpha ligand of the cobamide synthesized by Salmonella typhimurium. Nutritional characterization of mutants defective in biosynthesis of the imidazole ring

The Co beta-cyano derivative of the cobamide isolated from Salmonella typhimurium was identified as Co alpha-(alpha-5,6-dimethylbenzimidazolyl)-Co beta-cyanocobamide, indicating that this bacterium synthesizes 5,6-dimethylbenzimidazole (DMB) de novo. We found that mutants deficient in the synthesis of DMB can incorporate benzimidazole without modification to form Co alpha-(alpha-benzimidazolyl)cobamide, a cobamide that is physiologically active. The analysis of the nutritional requirements of mutants deficient in DMB synthesis identified 4,5-dimethylphenylenediamine as a putative intermediate in the synthesis of the imidazole ring of DMB. Our results suggest that the CobII region of the cob operon of S. typhimurium only encodes functions involved in the synthesis of the imidazole ring of DMB.

Monoclonal antibody-colony immunoblot method specific for isolation of Pediococcus acidilactici from foods and correlation with pediocin (bacteriocin) production

BALB/c mice were immunized with broken, heat-killed cells of Pediococcus acidilactici H. After murine cell fusions, one monoclonal antibody (MAb), Ped-2B2, was selected on the basis of its positive reaction with seven of seven strains tested in an enzyme-linked immunosorbent assay with whole cells of P. acidilactici. The MAb Ped-2B2 did not show any cross-reactions with other lactic-acid bacteria or other gram-positive or gram-negative organisms. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot (immunoblot) analysis of surface proteins of P. acidilactici indicated that Ped-2B2 reacted with a protein of 116 kDa. MAb Ped-2B2 was used as a probe to isolate Pediococcus species from fermented-meat products by colony immunoblotting. A total of 18 Ped-2B2-reactive Pediococcus spp. isolates were isolated from eight food samples and assayed for bacteriocin production. All of the isolates produced bacteriocins which were heat stable, proteinaceous, and inhibitory to Lactobacillus plantarum NCDO 955. Biochemical characterization of these isolates indicated that they were all P. acidilactici.

Monoclonal antibody specific for Listeria monocytogenes associated with a 66-kilodalton cell surface antigen

A monoclonal antibody (MAb), EM-7G1, specific for Listeria monocytogenes was developed by using a previously developed MAb, C11E9 (A. K. Bhunia, P. H. Ball, A. T. Fuad, B. W. Kurz, J. W. Emerson, and M. G. Johnson, Infect. Immun. 59:3176-3184, 1991), to mask epitopes shared by L. monocytogenes and Listeria innocua in a 66-kDa cell surface protein. MAb EM-7G1 was an immunoglobulin subclass G1 antibody with kappa light chains. This MAb reacted with all 34 strains of L. monocytogenes tested and showed no cross-reaction with other Listeria spp. or other gram-positive or gram-negative organisms tested by enzyme-linked immunosorbent assay, dot blotting, and colony blotting. A second MAb, EM-6E11, reacted with all Listeria spp. tested but no other bacteria. In a Western blot (immunoblot) assay, EM-7G1 reacted with a crude cell surface protein of 66 kDa with a pI value of 6.7, while EM-6E11 reacted with two protein bands of 43 and 94 to 97 kDa with pI values of 4.0 and 4.3, respectively. Results with trypsin or pronase treatments indicated that the cell antigen reacting with EM-7G1 was on the surface of L. monocytogenes V7 and Scott A cells.

Development of cell surface protein associated gene probe specific for Listeria monocytogenes and detection of the bacteria in food by PCR

A genomic library of L. monocytogenes was constructed using lambda Zap II-Eco RI and screened with a monoclonal antibody which is specific for a Listeria cell surface protein. Three positive clones each contained a 6.5 kb insert which in E. coli could express the same Listeria protein. The 6.5 kb insert was further digested with Hin dIII and the smaller fragments were subcloned into a plasmid vector (pBluescript) and screened with 32P-labelled genomic DNA from L. monocytogenes or L. innocua. Three clones which were positive with L. monocytogenes and negative with L. innocua were screened and each contained a 2.1 kb insert. The 2.1 kb insert was partly sequenced and some candidate oligomer probes from the sequences were selected and compared with sequences in a Genbank computer search. One such oligomer probe (T7-list) was confirmed to be specific for L. monocytogenes. The probe hybridized with all 28 strains of L. monocytogenes tested, but not with any of six other Listeria species nor 11 other bacteria tested. Using this probe-primer, a PCR method was developed which could detect as few as 2 cfu of L. monocytogenes in pure cultures, and as few as 4-10 cfu of L. monocytogenes when inoculated into foods.

The CobII and CobIII regions of the cobalamin (vitamin B12) biosynthetic operon of Salmonella typhimurium

A detailed deletion map of the CobII and CobIII regions of the cobalamin biosynthetic (cob) operon of Salmonella typhimurium LT2 has been constructed. The CobII region encodes functions needed for the synthesis of lower ligand 5,6-dimethylbenzimidazole (DMB); CobIII encodes functions needed for the synthesis of the nucleotide loop that joins DMB to the corrin macrocycle. The genetic analysis of 117 deletion, insertion, and point mutations indicates that (i) the CobII and CobIII mutations are contiguous--that is, they are grouped according to function; (ii) the CobII region is composed of four complementation groups (cobJKLM); (iii) cobM mutations do not complement mutations in any of the other three CobII groups; and (iv) CobIII mutations include three complementation groups that correspond to the cobU, cobS, and cobT genes.

Development of a 16S rRNA-based oligomer probe specific for Listeria monocytogenes

Crude rRNA was isolated from Listeria monocytogenes, L. innocua, and L. ivanovii and sequenced by a reverse transcriptase method. Only two sequence regions were found to differ for L. monocytogenes versus L. innocua or L. ivanovii. Two oligonucleotide probes (RL-1 and RL-2) complementary to these two regions of rRNA of L. monocytogenes were synthesized. The RL-1 probe had one base while the RL-2 probe had two bases which differed for L. monocytogenes versus L. innocua and L. ivanovii. Use of a dried gel hybridization in place of Northern (RNA) hybridization or dot blot hybridization indicated that the RL-2 probe hybridized with all 36 strains of L. monocytogenes tested but not with 6 other Listeria species and 11 other bacteria tested. The RL-2 probe is specific for L. monocytogenes, while the RL-1 probe showed some cross-reactions with other Listeria species. An alkaline phosphatase-labeled RL-2 probe could be used in a dot blot hybridization test and gave good results, but a 32P-labeled RL-2 probe was more sensitive than the nonradioactive probe and the 32P-labeled probe was useable for up to 2 months, even though the 32P was highly degenerated.

Development and characterization of a monoclonal antibody specific for Listeria monocytogenes and Listeria innocua

BALB/c mice were immunized with crude cell surface proteins of Listeria monocytogenes V7. Approximately 1,680 hybridomas were generated after two fusions, and the monoclone C11E9 was selected and used for further characterization. The monoclonal antibody (MAb) produced by C11E9 was immunoglobulin subclass G2b with kappa light chains. Dot and colony blot results indicated that MAb C11E9 was reactive to all the L. monocytogenes (34 of 34) and Listeria innocua (6 of 6) isolates without any cross-reaction to other organisms tested. Western blot (immunoblot) analysis of crude cell surface proteins in native polyacrylamide gel electrophoresis (PAGE) indicated that MAb C11E9 reacts with a single band in each species, with a molecular mass of 174 kDa for L. monocytogenes and 182 kDa for L. innocua. The MAb reacted with one major protein band in Western blot from acid-urea PAGE for both L. monocytogenes and L. innocua. Isoelectric focusing results indicated two immunoreactive protein bands with pIs of 8.1 and 7.4 for L. monocytogenes. Sodium dodecyl sulfate (SDS)-PAGE and Western blot analysis indicated several proteins with molecular masses of 76, 66, 56, and 52 kDa for L. monocytogenes and 66, 56, and 52 kDa for L. innocua. Reaction of MAb C11E9 to washed live cells indicated the possible binding of antibody to cell surface antigen. These cell surface antigens could be removed by 1 N HCl plus 9 M urea, 2% SDS-0.5% beta-mercaptoethanol, or 4 M guanidine-HCl. The epitope of MAb C11E9 binding site was shown to be protein in nature. Periodic acid-Schiff staining and glycoprotein immunoassay indicated that carbohydrate was absent in the epitope. The cellular locations of the MAb C11E9-reactive antigens were calculated to be 76 and 90% outside and 24 and 10% inside the cell membranes of L. monocytogenes and L. innocua, respectively, for 12- to 14-h cultures.

Dried gel hybridization in place of southern hybridization for detection of Listeria monocytogenes DNA fragments

A simple, sensitive, dried gel DNA hybridization method for detection of Listeria monocytogenes DNA fragments is described. DNA samples were fractionated on an agarose gel. The gel was then denatured in NaOH-NaCl and neutralized in Tris-NaCl. The resulting agarose gel was dried and hybridized with 32P-labelled DNA probe. No transfer to nitrocellulose membranes was used.

Surgical audit: variations in wound infection rates of individual surgeons

A prospective survey of 1086 general surgical in-patients was carried out in West Dorset district to determine the incidence of postoperative infections for individual surgeons. A total of 79 cases were diagnosed as having become infected, resulting in an overall infection rate of 7.3%. For all cases the infection rate for individual surgeons varied from 3.9 to 14.6% (P less than 0.005; chi 2 test). For the clean operative category only, the infection rate varied from 2.9 to 20.0% (P less than 0.0005; chi 2 test). The results demonstrate the value of routine surgical audit in elaborating the variation in clinical outcomes for individual surgeons. Clinical audit can identify the need for extra supervision and training of junior staff and peer review for senior clinicians.

The functional role of cysteines in isopenicillin N synthase. Correlation of cysteine reactivities toward sulfhydryl reagents with kinetic properties of cysteine mutants

Isopenicillin N synthase (IPNS) from Cephalosporium acremonium contains 2 cysteine residues in positions 106 and 255 which are invariant in all IPNS sequences reported to date (Miller, J.R., and Ingolia, T.D. (1989) Mol. Microbiol. 3, 689-695). Although these residues have been postulated to play a role in catalysis (Samson, S.M., Chapman, J.L., Belagaje, R., Queener, S., and Ingolia, T.D. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 5705-5709) as well as enzyme inactivation (Perry, D., Abraham, E.P., and Baldwin, J.E. (1988) Biochem. J. 255, 345-351) little information exists regarding their oxidation state and reactivity. In this paper, the functions of these cysteines have been addressed by chemical modification techniques in combination with site-directed mutagenesis. In the intact wild type protein, both cysteines are inert toward 5,5'-dithiobis-(2-nitrobenzoic acid) and iodoacetic acid. However, Cys-106, but not Cys-255, can be slowly modified by N-ethylmaleimide, and its modification is partially blocked by the presence of a substrate analog inhibitor. Complete modification of both cysteines by sulfhydryl reagents requires unfolding of the protein but not the presence of a disulfide reducing agent. The thiol content of IPNS is shown to be the same before and after exposing the enzyme to substrate even though during catalysis the enzyme is rapidly inactivated. The impact on catalysis due to alteration of the cysteines has been assessed using three site-specific mutants: Cys-106----Ser, Cys-255----Ser, and Cys-106,255----Ser. These mutant proteins have been purified as apoenzymes with the nature of the mutation verified by peptide mapping. The stoichiometry of metal required for activity remains as one equivalent of Fe2+/mol of enzyme in the mutants as in wild type IPNS. Compared with wild type, Cys-255----Ser shows a reduction in Vmax by 33%, and an increase in Km by 1.4-fold, while Cys-106----Ser and Cys-106,255----Ser, which have identical kinetic properties, exhibit a decrease in Vmax by 63% but an elevation of Km by 14-fold. The data presented demonstrate that 1) both cysteines are free thiols; 2) Cys-106 is more exposed than Cys-255; 3) substrate-induced inactivation is not caused by cysteine modification; 4) neither cysteine is absolutely essential for bond making or breaking events during catalysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Heritability of craniometric and occlusal variables: a longitudinal sib analysis

There has long been interest in the inheritance of malocclusion, but few studies have distinguished between skeletal (craniometric) variables and occlusal, tooth-based variables (e.g., anterior irregularity, rotations, displacements). This study was based on serial assessments of untreated persons in 30 sibships from 4 years (full deciduous dentition) to 20 years of age (full permanent dentition) in the Bolton-Brush Growth Studies of Ohio. Results define a clear dichotomy: craniometric variables (k = 29) typically show significant additive components of variance; correlations increase from age 4 to age 20; and correlations average 0.43 at adulthood. Tooth-based variables of position and relationship (k = 21) reach significance only occasionally; correlations decrease with age to the extent that few variables for subjects at age 20 have a correlation significantly different from zero. In contrast to craniometric variables, which have high heritabilities, almost all of the occlusal variability is acquired rather than inherited.

Purification and analysis of the major components of chum salmon protamine contained in insulin formulations using high-performance liquid chromatography

A simple high-performance liquid chromatographic method has been developed for the rapid purification and analysis of protamine components contained in insulin formulations. Only a single step is needed to separate peptides whose compositions, sizes, and unusual isoelectric points (pI 13.8) are nearly identical. The method involves their isocratic separation on a reversed-phase column using a pH 2 phosphate buffer and a low acetonitrile content as an eluant. The purified chum salmon components were analyzed by amino acid analysis, solid-phase amino acid sequencing, carboxypeptidase B digests, insulin complexation analysis, and a mass spectrophotometric procedure which gives an accurate mass of the intact peptides. This HPLC purification technique may also be applicable to protamines and other highly basic peptides isolated from other sources.

Petite colony formation by Listeria monocytogenes and Listeria species grown on esculin-containing agar

Several strains of Listeria species formed petite-sized colonies from parent stock cultures when grown on agar media containing 0.2-1% (w/v) esculin. This was observed in Listeria monocytogenes (7/22 strains), L. innocua (1/3), L. grayi (1/1), L. seeligeri (1/3), and L. welshimeri (1/1), but not in L. ivanovii (0/1) and L. murrayi (0/1). This phenomenon was only observed on agar media that contained esculin. All petite isolates had biotyping profiles identical to their larger, normal-sized counterpart isolates. Normal and petite-sized isolates from two L. monocytogenes strains, Scott A and V7, were pathogenic to immunosuppressed white mice. On media containing 0.5% (w/v) esculin + ferric iron, Listeria cultures produced colony diameters intermediate in size between those of normal and petite cultures. When pregrown in glucose broth, all petite isolates demonstrated visible beta-glucosidase (esculinase) activity within 5 min, while the normal-sized isolates showed beta-glucosidase activity only after at least 20-70 min. This evidence suggests that cells forming petite colonies are beta-glucosidase constitutive variants within the parent population, while cells that form normal-sized colonies are inducible for beta-glucosidase (esculinase) activity. A possible role for the esculin hydrolysis product, esculetin, in causing petite colony formation is discussed.

Monoclonal antibody specific for Listeria monocytogenes, Listeria innocua, and Listeria welshimeri

Eight hundred fifty-nine murine hybridomas were produced from eight fusions, and 27 were characterized for secretion of antibodies reactive to Listeria monocytogenes. One monoclonal antibody (MAb), P5C9, reacted with all test strains of L. monocytogenes (31 of 31), L. innocua (3 of 3), and L. welshimeri (1 of 1) but not with any strains of the other four Listeria species or with any of 22 gram-positive or 11 gram-negative species of bacteria when tested in microtiter and dot blot enzyme immunoassays. Of the other 26 antibodies, 20 reacted with either L. monocytogenes Scott A or V7 and with some or all of the other six Listeria species but also cross-reacted with some or all of the non-Listeria bacteria tested. MAb P5C9 is of the immunoglobulin G1 murine subclass. In Western blot (immunoblot) analyses, this MAb reacted with a single antigen with a molecular weight of 18,500, and it is shared in common with all three reactive species, L. monocytogenes, L. innocua, and L. welshimeri. This antigen was extracted with detergent and appeared to be cell bound.

Inhibition of Listeria monocytogenes growth by the lactoperoxidase-thiocyanate-H2O2 antimicrobial system

The lactoperoxidase-thiocyanate-H2O2 system (LP system), consisting of lactoperoxidase (0.37 U/ml), KSCN (0.3 mM), and H2O2 (0.3 mM), delayed but did not prevent growth of L. monocytogenes Scott A at 5, 10, 20, and 30 degrees C in broth and at 20 degrees C in milk. The net lag periods determined spectrophotometrically varied inversely with temperature and were shorter at 5 and 10 degrees C for cultures from shaken versus from statically grown inocula. Lag periods for cultures from shaken and statically grown inocula, respectively, were 73 and 98 h at 5 degrees C, 22 and 32 h at 10 degrees C, both 8.9 h at 20 degrees C, and both 2.8 h at 30 degrees C. After the lag periods, the maximum specific growth rates were similar for each of the three treatments (complete LP system, H2O2 alone, or control broth) at 5, 10, and 20 degrees C and were 0.06 to 0.08, 0.09 to 0.1, and 0.32 to 0.36/h, respectively. At 20 degrees C in sterile reconstituted skim milk, the LP system restricted growth of Scott A, with log CFU counts per ml at 0, 36, and 68 h being 5.7, 6.4 and 7.9 (versus 5.7, 9.8, and 11.2 for controls). Possible explanations for the decreased lag times observed for cultures from aerobically grown inocula are discussed.

Disk Inoculum-Solid Medium Method To Test Carbon and Nitrogen Assimilation by Yeast Isolates

Carbon and nitrogen assimilation for 50 yeasts isolated from White Riesling fermentation were tested by using a disk inoculum-solid medium method. This method was quicker and gave results comparable to the conventional liquid medium methods. Yeast characteristics (growth response, pigment production, morphology) could also be compared with this method.

Persistence of Listeria monocytogenes in yogurt as determined by direct plating and enrichment methods

Listeria Selective Isolation Agar (LSI) and Modified Acriflavin Ceftazidime Esculin Agar (MACE) were compared to McBride Listeria Agar minus Blood (MLA-B) for ability to recover Listeria monocytogenes Scott A cells inoculated into commercial yogurt, pH 4.1, Yogurt was stored at 5 degrees C and sampled periodically over a 12 day period. LSI, MACE and MLA-B inhibited the growth of the two yogurt organisms but LSI and MACE gave better inhibition of other separately tested Gram-positive bacteria likely to be present in other fermented foods. Acid-stressed Listeria monocytogenes Scott A cells were optimally recovered by enrichment at 5 degrees C for 5-18 days in 0.1 M phosphate buffer, pH 7.2, followed by transfer to tryptic soy broth +0.5% yeast extract at 30 degrees C for 2 days. At low inoculum levels (10(2) cells/g yogurt), they were not detectable by direct plating or enrichment of yogurt after day 0. At high inoculum levels (10(7) cells/g yogurt), they were detectable up to day 6 but not at day 9 by direct plating on MLA-B, LSI or MACE with log counts per gram of yogurt being about 10 fold higher on LSI than on MACE or MLA-B. The above enrichment procedure permitted recovery on MLA-B, LSI, or MACE of viable Listeria cells from the day 9 samples found negative by direct plating.

Analysis of a mass colorectal cancer screening program for cost-effectiveness

Mass screening of the general population with the stool blood test is a costly means of increasing the incidence of colorectal cancer identification; however, the test is worthwhile as a screening tool in patients at risk. We found the incidence of positive results to increase with age, as does the risk of colorectal cancer. Further efforts to increase the incidence of colorectal cancer detection should be directed toward increasing the awareness of primary care physicians and improving their screening practices. We stress that high-risk populations should be given special attention and the use of flexible proctosigmoidoscopes should be encouraged.

Drugs, alcohol and road accidents in Tasmania

Drug analyses were performed on 200 blood samples that were taken for alcohol analysis from road users in Tasmania. Alcohol at a concentration of above 0.5 g was found in 75% of the samples, and other drugs were found in 17% of the samples. Cannabis was the most prevalent of these other drugs: it was detected in 6% of road users; benzodiazepine drugs were detected in 5% of road users; and barbiturate drugs were detected in 2% of road users. Alcohol was found in 50% and other drugs were found in 25%, of drivers, riders and pedestrians who were involved in road accidents that were serious enough to cause death or injury. In addition to alcohol, other drugs may be making a significant contribution to road accidents because all the drugs that were identified are capable of impairing psychomotor performance. Of particular concern is the prevalence of cannabis, which is an illegal drug, and barbiturate drugs, which are now prescribed rarely. A well-controlled study is required to quantitate the contribution of drugs other than alcohol to road accidents. In the meantime, drivers should be warned that drugs that depress the central nervous system can be expected to impair driving ability and to increase the risk of an accident.

Localization of quantitative changes in pulmonary beta-receptors in ovalbumin-sensitized guinea pigs

Impaired beta-receptor function has been postulated as one factor contributing to airway hyperreactivity in asthmatic patients. Although numerous indirect studies have cast doubt on this theory, none of these previous investigations has been able to directly measure changes in beta-receptor number on intrapulmonary structures capable of affecting the physiologic changes seen in this disease state. To help clarify the intrapulmonary location of such changes, a model of allergic bronchoconstriction was prepared by sensitizing guinea pigs to ovalbumin intraperitoneally (ip) 2 wk prior to testing (Group S). A second group of animals was sensitized to ovalbumin, then 2 wk later partially desensitized (Group D) during a 4- to 6-wk period by repeated exposure to increasing doses of nebulized ovalbumin with epinephrine rescue. Control animals received ip administered and nebulized normal saline alone. Pulmonary function assessed by plethysmography revealed an increase in airway resistance to 294 +/- 42% (SE) of control in Group S (p less than 0.005) and a decrease in dynamic compliance to 76 +/- 8% of control in Group D and 39 +/- 10% of control in Group S (p less than 0.002) after exposure to nebulized ovalbumin. Using L-[3H] dihydroalprenolol ([3H] DHA), beta-receptors were autoradiographically localized and quantitated in lung sections from all 3 groups. Significant decreases (p less than 0.02) in 3H-DHA binding were noted in alveolar and conducting airway epithelium, and bronchiolar and vascular smooth muscle in ovalbumin-exposed animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Decreased glucose stimulation threshold, enhanced insulin secretion, and increased beta cell coupling in islets of prolactin-treated rats

In order to determine the effect of lactogen on insulin secretion and junctional coupling among islet beta cells, ovine prolactin (oPRL) was infused by Alzet minipumps into female rats for 4 days. This treatment produced an oPRL level of 994 +/- 122 ng/ml which, combined with residual rat PRL (rPRL) (12 +/- 2 ng/ml), represented nearly a 20-fold increase from control (rPRL: 53 +/- 17 ng/ml). In addition, plasma insulin was increased nearly 50% (control: 21.9 +/- 3 microU/ml; experimental: 30.3 +/- 3 microU/ml; p less than 0.05). When pancreata from lactogen-treated and control animals were perfused with linear 30-200 mg/dl glucose gradients, the apparent glucose threshold for insulin secretion in the experimental group was nearly 33% lower than that of the controls (i.e., 70 +/- 4.6 mg/dl vs. 104 +/- 7.5 mg/dl; p less than 0.01). The oPRL treatment also increased dye coupling among beta cells. Central cells in islets isolated from lactogen-treated and control animals were injected with Lucifer Yellow CH to estimate the extent of gap junctional coupling. There was nearly a twofold increase in the projected area of dye transfer per injection in the experimental vs. the controls: 4,607 +/- 575 micron 2 vs. 2,302 +/- 474 micron 2, respectively; p less than 0.02. The effects of oPRL decreased the apparent glucose threshold for insulin release, increased the above-threshold glucose-induced insulin secretion, and increased the extent of dye coupling among beta cells. These changes in insulin secretion and dye coupling closely resemble those observed in islets from pregnant rats.

Sensitivity to bile salts of Shigella flexneri sublethally heat stressed in buffer or broth

Batch cultures of Shigella flexneri M4243 were grown at 37 degrees C in broth to early stationary phase, washed, and heated at 50 degrees C in 0.1 M phosphate buffer (pH 7.0). Cells were surface plated on a tryptic phytone glucose agar (TPGA), TPGA with 0.15 or 0.85% bile salts no. 3 (TPGA-BS 0.15 or TPGA-BS 0.85), or TPGA with 0.25 or 0.50% sodium deoxycholate (TPGA-DC 0.25 or TPGA-DC 0.50). Cells sampled after no heating produced colony counts on TPGA-BS 0.85 or on TPGA-DC 0.50 that were no more than about 0.5 log lower than for unheated cell samples plated on TPGA. Cells heated at 50 degrees C for 30 min produced colony counts on TPGA-DC 0.50 or on TPGA-BS 0.85 that were about 1.5 logs lower than on TPGA. Cells heated for 30 min and shifted to TPG broth at 37 degrees C to allow resuscitation required about 2 h to regain tolerance to 0.85% BS. However, heated cells resuscitated on solid TPGA at 35 degrees C before being challenged with overlays of TPGA-BS 0.85 or TPGA-DC 0.50 required 6 to 8 h on TPGA to regain tolerance to 0.85% BS or 0.50% DC. To regain tolerance to overlays of 0.15% BS or 0.25% DC, heated cells required resuscitation periods on TPGA of about 2 or 2 to 6 h, respectively. Cells heated in TPG broth and sampled after no heating produced colony counts on TPGA that were about 1.5 logs lower than for unheated cell suspensions, suggesting greater apparent injury when heat stressed in broth than in buffer.(ABSTRACT TRUNCATED AT 250 WORDS)

Operative treatment of cecal volvulus combining cecopexy with intestinal tube decompression

A new operative approach for non-gangrenous cecal volvulus combining transrectal Baker tube colonic decompression with peritoneal flap cecopexy has advantages over previously described operations.

Distribution and quantitative developmental changes in guinea pig pulmonary beta-receptors

Studies using tissue homogenates have demonstrated an increase in pulmonary beta-receptors during development. However, techniques using disrupted tissue have not permitted the precise anatomic localization of pulmonary beta-receptors or identification of structures where increases occur. Using L-[3H]dihydroalprenolol, beta-receptors were radioautographically localized and quantitated in sections of newborn (NB) and adult (A) guinea pig lung. Scatchard analysis showed a single class of binding sites with a maximum binding capacity of 189 +/- 3 (NB) and 305 +/- 37 (A) fmol X mg-1 protein (P less than 0.02). Binding was of high affinity with the dissociation constant (Kd) = 1.46 +/- 0.2 (NB) and 1.26 +/- 0.3 (A) nM (NS). The majority of beta-receptors were localized in alveolar wall and airway epithelia (alveolar much greater than bronchiolar greater than bronchial) (P less than 0.0001). Airway and vascular smooth muscle had significantly fewer demonstrable beta-receptors. The increased number of beta-receptors in the adult appeared to be due primarily to a 2.0 +/- 0.12-fold increase in alveolar wall and airway epithelia as opposed to only a 1.3 +/- 0.18-fold increase in the already low number in airway and vascular smooth muscle (P less than 0.05). While apparent receptor density may not necessarily correlate with physiological response or importance, radioautographic localization of pulmonary beta-receptors may significantly enhance our understanding of their role in normal and pathologic states.

Isolation and characterization of a genetic variant of bovine proinsulin

A genetic variant of bovine proinsulin has been isolated using preparative reverse-phase HPLC. The new proinsulin (bovine proinsulin II) differs from the known proinsulin (bovine proinsulin I) by a single amino acid residue at position C-48 in the connecting peptide. The amino acid replacement is a leucine substitution for proline. The two proinsulins were found in a ratio of approximately 9:1, proinsulin I: proinsulin II. No chemical or biological differences were observed for the two proinsulins other than their different elution times on reverse-phase HPLC.

Pancreatic polypeptide from rat pancreas

Pancreatic polypeptide (PP) has been isolated from rat pancreas by gel filtration, ion exchange chromatography, and high performance liquid chromatography. The isolation was monitored with a RIA, using antibody to the carboxyl-terminal hexapeptide of bovine PP. Rat PP contains 36 amino acids and is similar in composition to PP from other mammalian sources. The single methionine residue in the peptide appears to oxidize easily to the sulfoxide, thereby giving rise to two immunoactive peaks on high performance liquid chromatography. Reduction to the native peptide can be accomplished with mercaptoethanol. The PP content of rat pancreas is about 2 mg/kg. The amino acid sequence of rat PP is Ala-Pro-Leu-Glu-Pro-Met-Tyr-Pro-Gly-Asp- Tyr-Ala-Thr-His-Glu-Gln-Arg-Ala-Gln-Tyr-Glu-Thr-Gln-Leu-Arg-Arg-Tyr-Ile- Asn-Thr-Leu-Thr-Arg-Pro-Arg-Tyr-NH2. This sequence preserves characteristics necessary for stabilization of the compact globular conformation found in avian PP.