Probing the Degree of Coherence through the Full 1D to 3D Crossover.

We experimentally study a gas of quantum degenerate ^{87}Rb atoms throughout the full dimensional crossover, from a one-dimensional (1D) system exhibiting phase fluctuations consistent with 1D theory to a three-dimensional (3D) phase-coherent system, thereby smoothly interpolating between these distinct, well-understood regimes. Using a hybrid trapping architecture combining an atom chip with a printed circuit board, we continuously adjust the system's dimensionality over a wide range while measuring the phase fluctuations through the power spectrum of density ripples in time-of-flight expansion. Our measurements confirm that the chemical potential µ controls the departure of the system from 3D and that the fluctuations are dependent on both µ and the temperature T. Through a rigorous study we quantitatively observe how inside the crossover the dependence on T gradually disappears as the system becomes 3D. Throughout the entire crossover the fluctuations are shown to be determined by the relative occupation of 1D axial collective excitations.

Increased myocardial Rab GTPase expression: a consequence and cause of cardiomyopathy.

The Ras-like Rab GTPases regulate vesicle transport in endocytosis and exocytosis. We found that cardiac Rabs1, 4, and 6 are upregulated in a dilated cardiomyopathy model overexpressing beta(2)-adrenergic receptors. To determine if increased Rab GTPase expression can contribute to cardiomyopathy, we transgenically overexpressed in mouse hearts prototypical Rab1a, the small G protein that regulates vesicle transport from endoplasmic reticulum to and through Golgi. In multiple independent mouse lines, Rab1a overexpression caused cardiac hypertrophy that progressed in a time- and transgene dose-dependent manner to heart failure. Isolated cardiac myocytes were hypertrophied and exhibited contractile depression with impaired calcium reuptake. Ultrastructural analysis revealed enlarged Golgi stacks and increased transitional vesicles in ventricular myocytes, with increased secretory atrial natriuretic peptide granules and degenerative myelin figures in atrial myocytes; immunogold studies localized Rab1a to these abnormal vesicular structures. A survey of hypertrophy signaling molecules revealed increased protein kinase C (PKC) alpha and delta, and confocal microscopy showed abnormal subcellular distribution of PKCalpha in Rab1a transgenics. These results indicate that increased expression of Rab1 GTPase in myocardium distorts subcellular localization of proteins and is sufficient to cause cardiac hypertrophy and failure.

Coordinate regulation of glucocorticoid receptor and c-jun mRNA levels: evidence for cross-talk between two signaling pathways' at the transcriptional level.

Autologous regulation of steroid receptors by their cognate ligands has been demonstrated for a number of nuclear receptor family members. To determine the molecular mechanism for glucocorticoid receptor (GR) autoregulation, the expression of glucocorticoid receptor mRNA and protein levels were examined in the mouse AtT-20 pituitary tumor cell line. The expression of c-jun and c-fos mRNA and protein was also examined in the same cell extracts. A rapid down-regulation of the GR protein was observed after treatment with the glucocorticoid analog, triamcinolone acetonide (TA). An oscillatory, parallel regulation of both GR and c-jun mRNA levels occurred. In contrast, POMC mRNA levels remained at a stable, low level during chronic TA treatment. Dose-response analyses also revealed a coordinate down-regulation of GR and c-jun (but not POMC or c-fos) mRNA levels. FOS protein levels were unaffected by TA treatment. Surprisingly, JUN protein levels were increased by TA, even when the c-jun mRNA levels were decreasing. Perhaps a derepression of c-jun mRNA translation occurs after TA treatment, and this may be due to GR/JUN heteromer formation interfering with JUN repression of c-jun mRNA translation. The effect of TA on GR and c-jun gene expression was a primary effect, as it occurred rapidly and was not inhibited by cycloheximide (CHX). Nuclear run-on transcription assays revealed a rapid (15 min) down-regulation in both GR and c-jun gene transcription rates, while POMC gene transcription was unaffected at this early time. Treatment of AtT-20 cells with all-trans retinoic acid gave different kinetics for GR and c-jun mRNA regulation than obtained with TA; however, the GR and c-jun mRNA levels were still coordinately regulated after retinoic acid treatment. Based upon these data, the promoter structures of the GR and c-jun genes, and previously published results, a novel mechanism for the coupled regulation of GR and c-jun transcription, via a direct transcriptional interference with AP-1 (FOS/JUN) activity, is proposed.

Vibrio vulnificus septicemia. Isolation of organism from stool and demonstration of antibodies by indirect immunofluorescence.

Vibrio vulnificus was isolated from blood and stool cultures from a 65-year-old man who had underlying alcoholic liver disease. The patient had eaten raw oysters the day before he became ill. To our knowledge, this is the first published report of isolation of the organism from stool in a patient with primary septicemia, and it provides support for epidemiologic studies suggesting that the infection is acquired through the gastrointestinal tract by eating raw seafood containing the organism. It was also possible, in this case, to demonstrate the presence of high antibody titers to the blood isolate by indirect immunofluorescence but not by agglutinating or vibriocidal tests.

Cholera in Louisiana. Widening spectrum of seafood vehicles.

The largest cholera outbreak in the United States in over a century occurred in Louisiana from August through October 1986. Eighteen persons in 12 family clusters had stool culture or serologic evidence of infection with toxigenic Vibrio cholerae 0-group 1. Thirteen of these persons had severe diarrhea, and 4 required intensive care unit treatment. Although all 18 survived, 1 96-year-old woman with suspected cholera died shortly after hospital admission. A case-control study showed that case-patients were more likely than neighborhood control subjects to have eaten cooked crabs or cooked or raw shrimp during the week before illness. Case-patients who ate crabs were more likely than control subjects who ate crabs to have undercooked and mishandled the crabs after cooking. A third vehicle from the Gulf waters, raw oysters, caused V cholerae 01 infection in two persons residing in Florida and Georgia. All three seafood vehicles came from multiple sources. Stool isolates from the Louisiana case-patients were genetically identical to other North American strains isolated since 1973, but differ from African and Asian isolates. While crabs are the most important vehicle for V cholerae 01 infection in the United States, shrimp and oysters from the Gulf coast can also be vehicles of transmission. A persisting reservoir of V cholerae 01 along the Gulf coast may continue to cause sporadic cases and outbreaks of cholera in Gulf states and in states importing Gulf seafood.

Where's the beef? The role of cross-contamination in 4 chain restaurant-associated outbreaks of Escherichia coli O157:H7 in the Pacific Northwest.

BACKGROUND: From March through August 1993, outbreaks of Escherichia coli O157:H7 occurred at 4 separate Oregon and Washington steak and salad bar restaurants affiliated with a single national chain. OBJECTIVE: To determine the cause of outbreaks of E coli O157:H7 at 4 chain restaurants. METHODS: Independent case-control studies were performed for each outbreak. Available E coli O157:H7 isolates were subtyped by pulse-field gel electrophoresis and by phage typing. RESULTS: Infection was not associated with beef consumption at any of the restaurants. Implicated foods varied by restaurant but all were items served at the salad bar. Among the salad bar items, no single item was implicated in all outbreaks, and no single item seemed to explain most of the cases at any individual restaurant. Molecular subtyping of bacterial isolates indicated that the first 2 outbreaks, which occurred concurrently, were caused by the same strain, the third outbreak was caused by a unique strain, and the fourth was multiclonal. CONCLUSIONS: Independent events of cross-contamination from beef within the restaurant kitchens, where meats and multiple salad bar items were prepared, were the likely cause of these outbreaks. Meat can be a source of E coli O157:H7 infection even if it is later cooked properly, underscoring the need for meticulous food handling at all stages of preparation.

Shiga-like toxin-producing Escherichia coli O111 and associated hemolytic-uremic syndrome: a family outbreak.

OBJECTIVE: To describe a family cluster of Shiga toxin-producing Escherichia coli O111ac:NM infection. STUDY DESIGN: The index case was identified as part of a United States prospective study of hemolytic-uremic syndrome. Epidemiologic investigation was conducted through interviews. E. coli O111:NM infection was characterized through culture and serology. Shiga toxin 1 and 2 gene sequences were determined with oligonucleotide DNA probes. RESULTS: All three children and both parents had nonbloody diarrhea, vomiting and abdominal cramps, and one child developed hemolytic-uremic syndrome. Shiga toxin 1- and 2-producing E. coli O111ac:NM was isolated from two children. IgG antibodies to E. coli O111 were detected in all three children. CONCLUSIONS: To our knowledge this is the first reported cluster of O111 infection and only the second caused by non-O157 Shiga toxin-producing E. coli in North America.

Cholera.

Few diseases invoke public fear as readily as cholera. In its most severe state, cholera can cause death from hypotensive shock within 12 h of the first symptom. Cholera typically occurs in epidemics, spreading rapidly within the community, especially if hygeinic conditions are poor. Fortunately, effective water treatment has limited the spread of cholera in most of the developed world, and the treatment of cholera by oral rehydration has dramatically reduced the mortality rate.

Analysis of Salmonella enterica serotype Typhi pulsed-field gel electrophoresis patterns associated with international travel.

Typhoid fever is a significant cause of morbidity and mortality worldwide, causing an estimated 16 million cases and 600,000 deaths annually. Although overall rates of the disease have dramatically decreased in the United States, the number of travel-related infections has increased in recent decades. Drug resistance among Salmonella enterica serotype Typhi strains has emerged worldwide, making antimicrobial susceptibility testing an important function in public health laboratories. Pulsed-field gel electrophoresis (PFGE) subtyping of food-borne and waterborne pathogens has proven to be a valuable tool for the detection of outbreaks and laboratory-based surveillance. This retrospective study examined the distribution of PFGE patterns of S. enterica serotype Typhi isolates from patients with a history of international travel. Isolates were collected as part of a passive laboratory-based antimicrobial susceptibility surveillance study. Isolates were PFGE subtyped by using the restriction enzyme XbaI to restrict the total genomic DNA. Isolates indistinguishable with XbaI were further characterized using the restriction enzyme BlnI. A total of 139 isolates were typed, representing travel to 31 countries. Restriction fragment patterns consisted of 14 to 18 fragments ranging in size from 580 to 40 kbp. Seventy-nine unique PFGE patterns were generated using XbaI. Isolates from the same geographic region did not necessarily have similar PFGE patterns. Of the 139 isolates, 46 (33%) were resistant to more than one antimicrobial agent (multidrug resistant [MDR]). Twenty-seven (59%) of 46 MDR isolates had indistinguishable PFGE patterns with both XbaI and BlnI. It appears that MDR S. enterica serotype Typhi has emerged as a predominant clone in Southeast Asia and the Indian subcontinent.

Improvement of the indirect hemagglutination assay for Salmonella typhi Vi antibodies by use of glutaraldehyde-fixed erythrocytes.

Glutaraldehyde-fixed sheep erythrocytes sensitized with Vi antigen were shown to be usable for at least 1 year in the indirect hemagglutination assay for Vi antibodies. The use of fixed sensitized erythrocytes improves the practicality of the indirect hemagglutination assay by (i) eliminating the need to sensitize cells each time the test is performed; (ii) reducing waste of the purified Vi antigen; and (iii) reducing test-to-test variation.

Epidemiological usefulness of changes in hemolytic activity of Vibrio cholerae biotype El Tor during the seventh pandemic.

Hemolytic Vibrio cholerae biotype El Tor strains were isolated in the United States in 1973 and 1978 after they had supposedly disappeared worldwide during the 1960s and 1970s. We decided to examine the change in prevalence of hemolytic El Tor strains since the beginning of the seventh pandemic and evaluate the usefulness of hemolytic activity as an epidemiological marker. A total of 48 isolates of V. cholerae biotype El Tor isolated in the Eastern Hemisphere between 1960 and 1979, along with 1 Texas (1973) and 38 Louisiana (1978) isolates, were tested for hemolytic activity by each of four methods. One method (utilizing heart infusion broth with 1% glycerol) was slightly superior for detecting hemolytic activity. Titers obtained with this method ranged from less than 2 to 1,024. Of 13 (76.9%) strains from the earliest part of the current pandemic, 10 were hemolytic, compared with 1 of 26 (3.8%) strains isolated in the period from 1966 to 1979 in the Eastern Hemisphere, indicating that nonhemolytic El Tor strains have replaced the hemolytic variety there. In contrast, all 38 Louisiana isolates and the Texas isolate were strongly hemolytic. Hemolytic activity was concluded to be a useful epidemiological marker.

Occupancy and composition of proteins bound to the AP-1 sites in the glucocorticoid receptor and c-jun promoters after glucocorticoid treatment and in different cell types.

The glucocorticoid receptor (GR) and c-jun promoters both contain activator protein-1 (AP-1) sites (GR AP-1 site and c-jun AP-1 site, respectively) that vary from the consensus AP-1 site. Electrophoretic mobility shift assays (EMSAs) were used to monitor GR AP-1 and c-jun AP-1 oligonucleotide binding by nuclear extracts from AtT-20 and L929 cells that were hormone- and vehicle-treated for 1, 6, or 24 h. Both AtT-20 and L929 cell nuclear extracts bound the c-jun AP-1 site somewhat better than the GRAP-1 site and, in the majority of cases, extracts from hormone-treated cells shifted both GRAP-1 and c-jun AP-1 oligonucleotides more than nontreated nuclear extracts. Supershift assays, using Jun and Fos family member-specific antibodies, showed that protein complexes formed by AtT-20 cell nuclear extracts bound to the c-jun AP-1 site were comprised of Jun family members, JunD, JunB, and cJun. No Fos family members were present. However, protein complexes from AtT-20 nuclear extracts that bound the GR AP-1 site were supershifted by JunD, JunB, cJun, and Fra-2 specific antibodies. In L929 cell nuclear extracts, the c-jun AP-1 site is bound by JunD and cJun. No clear association of Fos family members with the c-jun AP-1 site could be demonstrated. The GR AP-1 site bound protein complexes composed of JunD, JunB, Fra-2, and Fra-1 from L929 nuclear extracts. This demonstrates that the composition of the protein complexes that associate with the c-jun AP-1 site differs from those that bind the GR AP-1 site. These data also indicate that the protein complexes that bind the GR and c-jun AP-1 sites are cell-type-specific. Computer analysis also revealed five putative cyclic AMP response elements (CREs) in the GR promoter. Relative mobility shift and binding studies suggest that CRE binding protein (CREB), CREB modulator (CREM), or CREB/CREM may be associated with the c-jun AP-1 and/or GR AP-1 sites, but the association at these sites occurs at a lower binding affinity than for a consensus CRE. Nuclear extracts from AtT-20 and L929 cells were able to shift the CRE, and supershift analysis revealed that Jun family members are part of the protein complexes that bind the CRE. Pan Jun and pan Fos antibodies were able to supershift protein-CRE complexes formed using NIH 3T3 nuclear extracts. These data raise the possibility that the promiscuous binding of CREB and/or CREM to the AP-1 site, and AP-1 transcription factors to one or more CREs, in the GR promoter may contribute to the regulation of GR gene expression.

Steroid receptors at the nexus of transcriptional regulation.

During the past few years, our understanding of nuclear receptor action has dramatically improved as a result of the identification and functional analysis of co-regulators such as factors involved in chromatin remodeling, transcription intermediary factors (co-repressors and co-activators), and direct interactions with the basal transcriptional machinery. Furthermore, the elucidation of the crystal structures of the empty ligand-binding domains of the nuclear receptor and of complexes formed by the nuclear receptor's ligand-binding domain bound to agonists and antagonists has contributed significantly to our understanding of the early events of nuclear receptor action. However, the picture of hormone- and hormone receptor-mediated mechanisms of gene regulation remain incomplete and extremely complicated when one also considers the "nontraditional" interactions of hormone-activated nuclear receptors, for example, interactions between the activated steroid receptors and components of the chromatin/nuclear matrix; and finally the nongenomic effects that steroid hormones can exhibit with other signaling pathways. In this prospectus on steroid receptors, we discuss the implications of various steroid hormone and nuclear receptor interactions and potential future directions of investigation.

Trimethoprim activity in media selective for Campylobacter jejuni.

The activity of trimethoprim (TMP) in two selective media used for isolation of Campylobacter jejuni was evaluated. The two selective media, Campy-BAP and Skirrow medium, contain TMP in addition to other antimicrobial agents. The minimal inhibitory concentrations of TMP in blood agar base (basal agar for Skirrow medium) or brucella agar (basal agar for Campy-BAP) for three sensitive control organisms were compared with those in Mueller-Hinton agar, which contains low levels of thymidine. TMP was inactive in both blood agar base and brucella agar, even when lysed horse blood or thymidine phosphorylase was added. TMP had activity when used in combination with the other antimicrobial agents normally included in Skirrow medium and Campy-BAP, probably indicating synergism between TMP and one or more of the other antimicrobial agents. Sheep blood could be substituted for lysed horse blood in Skirrow medium without compromising the activity of TMP.

Some structures and processes of human epithelial cells involved in uptake of enterohemorrhagic Escherichia coli O157:H7 strains.

Several enterohemorrhagic Escherichia coli (EHEC) strains of serotype O157:H7 isolated from patients with hemorrhagic colitis, ischemic colitis, or hemolytic uremic syndrome were all found to be able to invade certain human epithelial cell lines in vitro. Their ability to gain entry into epithelial cells was compared with those of known invasive Shigella flexneri and Salmonella typhi strains and the noninvasive E. coli strain HB101 in invasion assays utilizing gentamicin to kill extracellular bacteria. All EHEC strains under investigation were efficiently internalized into T24 bladder and HCT-8 ileocecal cells. In striking contrast to shigellae, the same EHEC strains were not taken up into human embryonic intestinal INT407 cells or HEp-2 cells any more than the noninvasive E. coli strain HB101. The mechanism(s) of EHEC internalization was characterized by comparing the invasion efficiencies in the absence and presence of a variety of inhibitors acting on structures and processes of prokaryotic or eukaryotic cells. Also, wild-type, plasmid-containing EHEC strains were compared with their plasmid-cured isogenic derivative strains to determine if plasmid genes affect invasion ability. Plasmid-cured EHEC invaded as well as wild-type EHEC, indicating that invasion ability is chromosomally encoded. Inhibition of bacterial protein synthesis by simultaneous addition of bacteria and chloramphenicol to the monolayer blocked EHEC uptake dramatically, suggesting the presence of an invasion protein(s) with a short half-life. Studies utilizing inhibitors which act on eukaryotic cells demonstrated a strong dependence on microfilaments in the process of uptake of all EHEC strains into both T24 and HCT-8 cells. In general, depolymerization of microtubules as well as inhibition of receptor-mediated endocytosis reduced the efficiency of EHEC invasion of T24 cells, whereas interference with endosome acidification reduced EHEC entry into only HCT-8 cells. Taxol-induced stabilization of microtubules did not inhibit internalization into T24 cells or into the HCT-8 cell line. In marked contrast, the ability of S. typhi Ty2 to invade either cell line was inhibited only by depolymerization of microfilaments. In addition to the cell line specificity of EHEC invasion, not all EHEC strains displayed uniform behavior in the presence of inhibitors, suggesting the existence of variant uptake pathways in different strains. Most importantly, previous reports of the inability of EHEC to invade INT407 or HEp-2 cell lines support the currently held belief that EHEC strains are noninvasive.(ABSTRACT TRUNCATED AT 400 WORDS)