Food and animal sources of human Campylobacter jejuni infection.
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Animals↗
Biomedical subjects
J M Hunt
Publications and source records attributed to J M Hunt.
Detection of a genetic locus encoding resistance to rifampin in mycobacterial cultures and in clinical specimens.
The polymerase chain reaction (PCR) and automated DNA sequencing were used to detect a genetic locus, rpoB, associated with rifampin resistance in Mycobacterium tuberculosis (TB) in clinical isolates and directly in clinical specimens. Primers derived from the sequence of a TB rpoB gene fragment were used to amplify DNA from bacterial and mycobacterial isolates. An rpoB-specific PCR product was obtained for five of five TB, seven of eight other mycobacterial species, Nocardia sp., Corynebacterium sp., Streptomyces sp., Actinomyces sp., and Rhodococcus sp., but not for 15 isolates (eight genera) representing usual bacterial flora. Sequence comparison of the amplified rpoB region revealed the occurrence of TB-specific "signature nucleotides" at three positions. PCR yielded amplification products for seven of 16 clinical specimens. Five of the seven contained TB-specific DNA, as well as sequences that predicted rifampin susceptibility in accord with agar dilution results. None of ten specimens that were culture negative for TB yielded TB-specific PCR products. These results with a limited number of clinical specimens demonstrate the feasibility of direct detection by PCR of rifampin-resistant TB in clinical specimens. Such testing may serve as a rapid surrogate test for multidrug-resistant TB in laboratories with PCR and automated sequencing capability.
Base Sequence↗
A post-docking role for synaptobrevin in synaptic vesicle fusion.
We have used the squid giant synapse to determine the role of synaptobrevin, integral membrane proteins of small synaptic vesicles, in neurotransmitter release. The sequence of squid synaptobrevin, deduced by cDNA cloning, is 65%-68% identical to mammalian isoforms and includes the conserved cleavage site for tetanus and botulinum B toxins. Injection of either toxin into squid nerve terminals caused a slow, irreversible inhibition of release without affecting the Ca2+ signal which triggers release. Microinjection of a recombinant protein corresponding to the cytoplasmic domain of synaptobrevin produced a more rapid and reversible inhibition of release, whereas two smaller peptide fragments were without effect. Electron microscopy of tetanus-injected terminals revealed an increased number of both docked and undocked synaptic vesicles. These data indicate that synaptobrevin participates in neurotransmitter release at a step between vesicle docking and fusion.
Amino Acid Sequence↗
Reduction by intracellular calcium chelation of acetylcholine secretion without occluding the effects of adenosine at frog motor nerve endings.
1. The calcium chelators bis-(aminophenoxy)ethane-tetraacetic acid (BAPTA) or dimethyl-BAPTA (DMBAPTA) were introduced into the cytoplasm of frog motor nerve endings by use of the AM loading technique. The effects of intracellular Ca2+ chelation was studied on quantal acetylcholine (ACh) release and on the action of adenosine. 2. Intracellular BAPTA or DMBAPTA prevented the increases in quantal ACh secretion normally evoked by caffeine. 3. Intracellular DMBAPTA decreased the number of ACh quanta released by individual nerve impulses and virtually eliminated the fast phase of facilitation in response to paired nerve impulses. 4. Adenosine reduced both spontaneous and evoked secretion of ACh quanta with its usual potency and efficacy in the presence of intracellular DMBAPTA. Adenosine had no significant effect on facilitation. 5. The results, which suggest that adenosine and intracellular DMBAPTA reduce ACh secretion by different mechanisms, are consistent with the hypothesis that adenosine inhibits ACh release by reducing the ability of Ca2+ to promote ACh secretion from frog motor nerve endings.
Acetylcholine↗
The incidence of deep venous thrombosis in patients with superficial thrombophlebitis of the lower limbs.
PURPOSE: The purpose of this study was, first, to determine the incidence of underlying occult deep venous thrombosis (DVT) in patients with superficial thrombophlebitis and, second, to see if any risk factors are helpful in identifying these patients. METHODS: Forty-four consecutive patients with a clinical and duplex ultrasound-confirmed diagnosis of superficial thrombophlebitis were assessed for DVT. All patients had a duplex ultrasound study of the deep venous system. Standard thrombosis risk factors were assessed for each patient. RESULTS: Ten patients (23%) had DVT. All cases were clinically occult. One patient had propagated thrombus in the common femoral vein. Three patients had popliteal vein thrombi. The remaining patients had calf vein thrombus only. Four of these were not in continuity with the superficial thrombus. The site of the superficial thrombophlebitis was not predictive of DVT. None of the known venous thrombotic risk factors were helpful in identifying patients at risk for DVT. CONCLUSION: Noninvasive deep venous studies are recommended in all patients with lower limb superficial thrombophlebitis because of the high incidence of occult DVT. Patients with DVT can then be treated appropriately.
Female↗
Glomerular filtration rates in persons evaluated as living-related donors--are our standards too high?
We have retrospectively analyzed the glomerular filtration rate by 125-I iothalamate clearance and creatinine clearance in a group of 661 persons evaluated as potential kidney donors. The average GFR in this population is lower than that reported in previous studies and ranges from 102 +/- 15 and 114 +/- 17 ml/min for males and females age 21-30 to 84 +/- 13 and 79 +/- 15 ml/min for males and females age 51-60. Furthermore, there has been a gradual decrease in GFR in this population from 1970 to 1990 in both the entire population and in those under the age of 40. The cause of this drop is not apparent. These data can be utilized to determine the appropriateness of a potential donor for donation, and may indicate that our current standards are too high.
Adult↗
Ionomycin-induced acetylcholine release and its inhibition by adenosine at frog motor nerve endings.
1. Acetylcholine (ACh) evoked secretion by the calcium ionophore, ionomycin, was studied at frog motor nerve endings. 2. Bath application of ionomycin stimulated an irreversible increase in the rate of spontaneous, quantal ACh release in the presence of extracellular Ca2+. In contrast, local application of ionomycin stimulated a rapid, reversible acceleration of spontaneous ACh release. 3. The magnitude of the secretory response to ionomycin was dependent both upon the concentration of ionophore and the concentration of extracellular Ca2+. 4. Adenosine or 2-chloroadenosine inhibited ionomycin-stimulated ACh release with the same potency and efficacy observed previously for these adenosine analogues as inhibitors of ACh secretion evoked by nerve impulses. 5. These results support the conclusion that adenosine receptor activation inhibits quantal ACh secretion at a site distal to that of Ca2+ entry at frog motor nerve endings.
2-Chloroadenosine↗
Evaluation of commercially available acridinium ester-labeled chemiluminescent DNA probes for culture identification of Blastomyces dermatitidis, Coccidioides immitis, Cryptococcus neoformans, and Histoplasma capsulatum.
Four commercially available acridinium ester-labeled DNA probes directed against rRNA were evaluated for their ability to identify Blastomyces dermatitidis, Coccidioides immitis, Histoplasma capsulatum, and Cryptococcus neoformans in culture. rRNA was extracted by sonication of 1- to 2-mm2 portions of cultures of fungi in two chaotropic reagents with glass beads. Following a heat inactivation step, the extracts were hybridized in solution with probes specific for each pathogen. The acridinium ester reporter moiety of nonhybridized probe was selectively hydrolyzed, and chemiluminescence of specific DNA:RNA hybrids was quantitated in relative light units with a luminometer. A positive identification required a relative light unit value of > or = 50,000. Sensitivity and specificity of the probes were determined by probing cultures of the respective pathogenic fungi (target) and nontarget fungi. Both mycelial and yeast forms of the dimorphic fungi (B. dermatitidis and H. capsulatum) were tested. For B. dermatitidis, sensitivity and specificity were 87.8 and 100%, respectively (74 target and 219 nontarget fungi tested). For C. immitis, sensitivity and specificity were 99.2 and 100%, respectively (122 target and 164 nontarget fungi tested). For H. capsulatum, sensitivity and specificity were 100 and 100%, respectively (86 target and 154 nontarget fungi tested). For C. neoformans, sensitivity and specificity were 97 and 100%, respectively (100 target and 230 nontarget fungi tested). For B. dermatitidis, C. immitis, and C. neoformans, repeat testing increased the respective sensitivities to 97.3, 100, and 100%. The high sensitivities and specificities of the probes, the relatively short time (less than 1 h) required to perform the assay, and the availability of standardized reagent kits make the acridinium ester-labeled DNA probes well suited to laboratories in need of a rapid method to identify these fungal pathogens. Further, use of the probes to identify pathogenic fungi as soon as colonies appear on primary recovery media significantly shortens the time to reporting.
Acridines↗
Memory structure in the processing of advertising messages: how is unusual information represented?
Two models of memory structure--schema-copy-plus-tag (Graesser & Nakamura, 1982; Schmidt & Sherman, 1984) and associative-network/depth-of-processing (Craik & Lockhart, 1972; Hastie & Kumar, 1979)--were tested in a 2 x 2 between-subjects design. Type of argument (typical vs. atypical) and measurement interval (immediate vs. 2-day delay in recognition and recall) were manipulated in a print-advertising context. Results indicated that atypical arguments (unusual information) prompt deeper processing of the entire message (implying an associative-network memory structure) rather than some part of the message (as would be hypothesized by the schema-copy-plus-tag formulation) and that this effect prevails under both immediate- and delayed-measurement conditions.
Adult↗
Synergy between hepatitis B virus expression and chemical hepatocarcinogens in transgenic mice.
Exposure of female hepatitis B virus transgenic mice of lineage 50-4, which display liver injury secondary to overexpression of the gene for the large envelope polypeptide of hepatitis B virus, to the hepatocarcinogens aflatoxin and diethylnitrosamine produced more rapid and extensive evidence of nodule formation and oval cell proliferation, as well as the development of adenomas and primary hepatocellular carcinomas, than was seen in transgenic mice not exposed to carcinogens. Adult mice are known to be resistant to the effects of aflatoxin or diethylnitrosamine, and the livers of carcinogen-treated nontransgenic littermate controls were essentially normal. By the time of sacrifice (15 mo), 20 adenomas and 2 primary hepatocellular carcinomas were found in 26 transgenic mice given aflatoxin and 8 adenomas and 2 primary hepatocellular carcinomas were seen in the 8 mice exposed to diethylnitrosamine, but no adenomas or carcinomas were identified in the 10 transgenic mice not exposed to carcinogens. These results suggest that the chronic liver damage and repair caused by overexpression of the hepatitis B virus large envelope polypeptide in the hepatocytes of the transgenic lineage 50-4 act synergistically with chemical hepatocarcinogens to produce neoplasia of the liver.
Adenoma↗
The role of facility management in psychiatric hospitals.
Executive managers can ensure the most efficient management of the physical assets of their psychiatric hospital by involving the facility management staff in all phases of all planning and implementation. This paper stresses how maintaining expert in-house staff and equipping them with comprehensive computer-based tools results in the efficient use of available space and in good management of both capital and operating expenses. As the hospital liaison with outside design firms and regulatory agencies, the facility management staff can effectively communicate the facility's requirements and represent its interests.
Building Codes↗
Changes in the expression of class I major histocompatibility complex antigen RNA induced by interferon in rat hepatoma cells.
The rat hepatoma cell line 17X was studied to determine if it expressed major histocompatibility complex (MHC) class I antigen RNA and to see if interferon treatment would affect its expression. Under normal cell culture conditions, MHC class I RNA in 17X hepatoma cells is virtually undetectable. Administration of rat interferon at a concentration of 1000 units/ml for 48 h to 17X cells in culture resulted in the appearance of detectable levels of RNA for MHC class I antigens. The interferon-induced increase in class I RNA was accompanied by de novo synthesis of immunoprecipitable, metabolically radiolabeled class I antigens in the 17X hepatoma cells.
Animals↗
The effects of TMB-8 on acetylcholine release from frog motor nerve: interactions with adenosine.
The putative intracellular calcium (Ca) antagonist TMB-8 was shown to reduce postjunctional sensitivity and quantal acetylcholine (ACh) release at low micromolar concentrations. At 10-fold higher concentrations, TMB-8 also blocked caffeine-induced Ca release (as monitored electrophysiologically by changes in ACh release) but did not impair the ability of adenosine to inhibit quantal ACh release. This last result implies that TMB-8 and adenosine exert their inhibitory actions at different steps in the depolarization-secretion coupling sequence.
Acetylcholine↗
Natural cell-mediated immunity in the rabbit.
Susceptibility and resistance to tumors represent the interplay of many factors. One factor felt to govern the development of tumors is natural killer and natural cytotoxic cellular activity. The constitutional resistance of rabbits to spontaneous tumor development raises questions regarding the activity of natural cell-mediated immunity in this species. We therefore examined the ability of rabbit spleen, lymph node, and peripheral blood lymphocytes to mediate natural killer cell (NK) and natural cytotoxic cell (NC) activity in vitro. Using classical approaches to the study of NK and NC activity, we found no evidence of these activities in leporine spleen, lymph node, and peripheral blood lymphocytes. Preincubation of these cells with IL-2 did not induce such activity. Antibody-dependent cell-mediated cytotoxic reactivity (ADCC), which is believed to be mediated by NK cells, was also undetectable in rabbit lymphocytes. As controls, lymphocytes from other species were capable of mediating NK, NC, and ADCC functions normally in these experiments. Finally, we were unable to identify a population of large granular lymphocytes, the cells believed to mediate NK activity in other animals. Therefore, we could not demonstrate in the rabbit either natural cell-mediated immunity or the population of cells usually associated with natural cell-mediated immunity. If such activity exists in rabbits, it is different from that seen in other animals. More likely, the basis for the natural resistance of rabbits to tumor development must be sought elsewhere.
Animals↗
Prejunctional adenosine and ATP receptors.
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Acetylcholine↗
Manpower requirements for dental technicians.
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Dental Technicians↗
Change in the ploidy state of rat liver cells during chemical hepatocarcinogenesis and its relationship to the increased expression of alpha-fetoprotein.
The DNA content and ploidy state of cells isolated from the livers of rats exposed to the carcinogen 3'-methyl-4-dimethylaminoazobenzene for 10 and 20 weeks, as determined by flow cytometry, were correlated with the development of oval cells in the livers of treated animals and with serum levels of the oncoprotein alpha-fetoprotein (AFP). The study revealed that there was initially a steady rise in the AFP levels found in the carcinogen treated rats. Associated with this increase was a change in the ploidy pattern of the liver from an approximately equal mixture of tetraploid and diploid cells to a predominantly diploid state. Histologically, there was an increase in the number of oval cells during carcinogen treatment, and when stained immunohistochemically for AFP, these cells were positive. We conclude that the changing state of the diploid and tetraploid cell populations is due to the proliferation of oval cells and that these cells are responsible for the initial increase of serum AFP. The maintenance of the diploid population of cells at later periods of the study is a reflection of the persistence of a new cell type, possibly derived from oval cells. The effect of 3'-methyl-4-dimethylaminoazobenzene was not reversed if the animals were withdrawn from the diet at 10 weeks. In addition, in the cases of hepatocellular carcinoma that were found, a population of cells was detected by flow cytometry that contained altered DNA.
Animals↗
Different lineages of chemically induced hepatocellular carcinoma in rats defined by monoclonal antibodies.
Different lineages of hepatocellular carcinoma (HCC) were identified by the application of selected monoclonal antibodies to the study of the sequential histopathological changes which occurred during two regimens of chemical carcinogenesis in the rat. One regimen, that of Solt-Farber, caused prominent oval cell proliferation and large multiple neoplastic nodules, and the other regimen, continuous administration of diethylnitrosamine, produced minimal oval cell proliferation and a few small nodules. However, both regimens produce HCC in most exposed rats. Three monoclonal antibodies to liver cells, OV-6, H-4, and T-6, were selected on the basis of different tissue staining. OV-6 stains the cytoskeleton of bile duct cells, oval cells, and HCC but not that of hepatocytes. H-4 stains the cytoplasm of hepatocytes but of not hepatomas. T-6 stains the cytoskeleton of HCC only. In the Solt-Farber model, the monoclonal antibodies identified groups of hepatocytes within the persistent neoplastic nodules which had acquired the OV-6 epitope and had lost the H-4 epitope. HCC derived from this regimen had the same staining pattern, suggesting that the OV-6 positive H-4 negative hepatocytes were the precursors of the HCC. The presence within the nodules of oval cells, atypical duct structures, cells intermediate between duct cells and hepatocytes, and nodular hepatocytes all containing the OV-6 epitope raises the possibility that any of these cell types could serve as the precursor of the OV-6 positive hepatocytes that arose within the nodule. In the continuous diethylnitrosamine regimen a different staining pattern was seen. T-6 positive hepatocytes first appeared in periportal areas by the 5th week. These cells increased in numbers during the later weeks and with rare exceptions neither acquired the OV-6 epitope nor completely lost the H-4 epitope. Most HCC derived by the continuous diethylnitrosamine regimen were T-6 positive and OV-6 negative, suggesting a direct lineage from the periportal T-6 positive hepatocytes. These findings indicate that the lineage and phenotype of chemically induced HCC may vary with the carcinogenic regimen used and that HCC which arise in nodules may originate from cell types other than typical nodular cells.
2-Acetylaminofluorene↗