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Biomedical subjects

J D Oliver

Publications and source records attributed to J D Oliver.

At least 19 recordsLinked to original sources
PubMed2005

Wound infections caused by Vibrio vulnificus and other marine bacteria.

Infections caused by Vibrio vulnificus were first reported in 1979 by Blake et al. of the US Centers for Disease Control. At that time described as a 'rare, unnamed halophilic lactose-fermenting Vibrio species', V. vulnificus has emerged as the most virulent foodborne pathogen in the United States with a hospitalization rate of 0.910 and a case-fatality rate of 0.390. It is in addition a significant cause of potentially life-threatening wound infections. Infections following ingestion of raw or undercooked seafood, commonly raw oysters, can lead to a primary septicaemia with a fatality rate of 50-60%. An unusual symptom, occurring in 69% of 274 cases reviewed by Oliver, is the development of secondary lesions, typically on the extremities, which are generally severe (often a necrotizing fasciitis) and require tissue debridement or amputation. These cases occur almost exclusively in males over the age of 50 years. Interestingly, this gender specificity has been found to be due to the female hormone oestrogen, which in some manner provides protection against the lethal V. vulnificus endotoxin. Further, most cases occur in persons with certain underlying diseases which are either immunocompromising or which lead to elevated serum iron levels (e.g. liver cirrhosis, chronic hepatitis, haemochromatosis). V. vulnificus infections resulting in primary septicaemia have been extensively studied, and the subject of several reviews. This review concentrates on the wound infections caused by this marine bacterial pathogen, including the more recently described biotypes 2 and 3, with brief discussions of those caused by other marine vibrios, and the increasingly reported wound/skin infections caused by Mycobacterium marinum, Erysipelothrix rhusiopathiae, and Aeromnonas hydrophila.

Adolescent↗
PubMed2003

A comparison of thiosulphate-citrate-bile salts-sucrose (TCBS) agar and thiosulphate-chloride-iodide (TCI) agar for the isolation of Vibrio species from estuarine environments.

AIMS: The purpose of this study was to compare a recently described medium, thiosulphate-chloride-iodide (TCI), for the isolation of estuarine vibrios with thiosulphate-citrate-bile salts-sucrose (TCBS). METHODS: A total of 492 colonies which developed on these media from estuarine water samples taken monthly over a 10-month period were examined. RESULTS: A much larger number of colonies developed on TCBS than TCI, and minimal taxonomic criteria indicated that a higher percentage (61%) of TCBS colonies could be identified as Vibrio spp. when compared with TCI (46%). SIGNIFICANCE: This study suggests that TCBS is a superior medium when compared with TCI for the isolation of Vibrio spp. from estuarine waters. Because of the public health risk presented by V. vulnificus, V. parahaemolyticus, V. cholerae and other vibrios, the selection of the most appropriate medium for their isolation is extremely important.

Agar↗
PubMed2003

RpoS-dependent stress response and exoenzyme production in Vibrio vulnificus.

Vibrio vulnificus is an estuarine bacterium capable of causing rapidly fatal infections through both ingestion and wound infection. Like other opportunistic pathogens, V. vulnificus must adapt to potentially stressful environmental changes while living freely in seawater, upon colonization of the oyster gut, and upon infection of such diverse hosts as humans and eels. In order to begin to understand the ability of V. vulnificus to respond to such stresses, we examined the role of the alternate sigma factor RpoS, which is important in stress response and virulence in many pathogens. An rpoS mutant of V. vulnificus strain C7184o was constructed by homologous recombination. The mutant strain exhibited a decreased ability to survive diverse environmental stresses, including exposure to hydrogen peroxide, hyperosmolarity, and acidic conditions. The most striking difference was a high sensitivity of the mutant to hydrogen peroxide. Albuminase, caseinase, and elastase activity were detected in the wild type but not in the mutant strain, and an additional two hydrolytic activities (collagenase and gelatinase) were reduced in the mutant strain compared to the wild type. Additionally, the motility of the rpoS mutant was severely diminished. Overall, these studies suggest that rpoS in V. vulnificus is important for adaptation to environmental changes and may have a role in virulence.

Culture Media↗
PubMed2003

Survival of Helicobacter pylori in a natural freshwater environment.

The mode by which Helicobacter pylori, the causative agent of most gastric ulcers, is transmitted remains undetermined. Epidemiological evidence suggests these organisms are waterborne; however, H. pylori has rarely been grown from potential water sources. This may be due to the ability of this organism to rapidly enter the viable but nonculturable (VBNC) state. Our investigation examines the entrance of H. pylori into this state in laboratory cultures and a natural freshwater environment as well as the relationship between morphology and culturability. To this end, membrane diffusion chambers were utilized to expose the cells to the natural fluctuations of a freshwater stream. In both the laboratory and environment, samples were assayed for culturability using plate counts and stained using a LIVE/DEAD BacLight assay for viability and morphological determinations. Additionally, water samples were collected, six environmental parameters were measured, and resuscitation conditions were examined. H. pylori was observed to lose culturability in the laboratory and stream, although viability was maintained. While the results of our study agree with those of previous studies which suggested that there is a transition in morphology from rods to cocci as culturability is lost, the morphological distribution of cells did not change as culturability was lost in the environment. The majority of cells in the VBNC state in the laboratory are cocci; however, all morphological forms were present in the environment. The results of these studies suggest that H. pylori persists in laboratory cultures and the environment in the VBNC state and that cells in this state represent a public health hazard.

Bacteriological Techniques↗
PubMed2003

Use of diacetyl to reduce the load of Vibrio vulnificus in the Eastern oyster, Crassostrea virginica.

Vibrio vulnificus is a highly virulent human pathogen that occurs naturally among the microflora of oysters. This organism has two portals of entry into humans, one of which is ingestion. Oysters containing V. vulnificus consumed in a raw or undercooked state often serve as a vehicle for the transmission of this organism. Previous studies conducted in our laboratory have examined various generally recognized as safe compounds and have determined that diacetyl, a component of butter, is among the most effective of these compounds in reducing loads of V. vulnificus in oysters. The purpose of this study was to further examine the role of diacetyl, along with that of depuration, in reducing loads of V. vulnificus. Shellstock oysters were treated with various concentrations of diacetyl, and we found that many of the oysters ceased pumping when diacetyl was added. The data obtained in this study indicated that treatment with diacetyl is ineffective; however, any reduction in V. vulnificus numbers may be masked when groups of oysters, some of which may not have taken up diacetyl, are sampled. We then investigated the efficacy of diacetyl in lowering levels of V. vulnificus in shucked oysters. Diacetyl was found to significantly reduce the load of V. vulnificus in shucked oysters containing natural populations. Overall, it appears that treatment with diacetyl is ineffective for shellstock oysters, although it has potential for use in reducing loads of V. vulnificus in shucked oysters.

Animals↗
PubMed2002

Effects of refrigeration and alcohol on the load of Aeromonas hydrophila in oysters.

Members of the bacterial genus Aeromonas are widely distributed throughout the environment and are readily cultured from a variety of foods. One member of this genus, Aeromonas hydrophila, has been reputed to be a significant cause of gastrointestinal disease. In this study, we examined the effects of refrigeration and alcohol on the level of A. hydrophila in oysters. Specifically, vodka was examined because it is used by the food service industry in preparation of Oysters Romanoff. One set of oysters was shucked on receipt, whereas others were refrigerated intact for 7 days at 5 degrees C. The oysters were blended and the numbers of A. hydrophila present determined using starch ampicillin agar. Oysters were also shucked and placed on the half shell with 5 ml of vodka for 10 min. The oysters were then washed and presumptive A. hydrophila levels determined in both the washate and homogenate. On the day of purchase, the average number of presumptive A. hydrophila found was 7.6 x 10(4) CFU/g of oyster meat. After 7 days of refrigeration, the average number had increased to 3.2 x 10(5) CFU/g of oyster meat. In the oysters treated with vodka, the average number of A. hydrophila present internally was 9.9 x 10(4) with high numbers (10(3) to 10(4)) isolated from the oyster surface. From these data, it is clear that refrigeration and alcohol treatment are not sufficient to reduce loads of A. hydrophila in or on oysters.

Aeromonas hydrophila↗
PubMed2001

Graft loss due to recurrent focal segmental glomerulosclerosis in renal transplant recipients in the United States.

Rates of and risk factors for graft loss and graft loss resulting from recurrent focal segmental glomerulosclerosis (FSGS) have not been studied in a national population. A retrospective analysis was performed on a national registry (1999 United States Renal Data System) of 101,808 renal transplant recipients (October 1, 1987, to December 31, 1996). Of these, 3,861 recipients of solitary renal transplants who had end-stage renal disease resulting from FSGS met inclusion criteria. Outcomes were graft loss and graft loss resulting from recurrent FSGS. As a percentage of all graft loss, recurrent FSGS accounted for 18.7% in living donor recipients and 7.8% in cadaveric recipients. In white recipients, the corresponding figures were 27% and 13%. In multivariate analysis, factors associated with graft loss resulting from recurrent FSGS were white recipient, donor African-American kidney in white recipient, younger recipient age, and treatment for rejection. African-American recipients had higher rates of graft loss overall. A living donor was associated with superior overall graft survival. Among renal transplant recipients with FSGS, white recipients had a higher risk of graft loss resulting from recurrent FSGS, disproportionately seen in recipients of African-American kidneys. The role of donor/recipient race pairing on graft loss resulting from recurrent FSGS should be validated. Living donor had no association with graft loss from recurrent FSGS after correction for other factors. African-American recipients with FSGS may have the most to gain from a living donor, given their improved graft survival and decreased risk of graft loss resulting from recurrent FSGS. This is a US government work. There are no restrictions on its use.

Analysis of Variance↗
PubMed2001

Essential role for estrogen in protection against Vibrio vulnificus-induced endotoxic shock.

Little is known about the underlying mechanisms that result in a sexually dimorphic response to Vibrio vulnificus endotoxic shock. V. vulnificus is a gram-negative bacterium, considered one of the most invasive and rapidly fatal human pathogens known. However, 85% of individuals that develop endotoxic shock from V. vulnificus are males. Using the rat, we have developed a model for V. vulnificus endotoxic shock that mimics the sexually dimorphic response in humans. Gonadectomy in females results in increased mortality, and estrogen replacement results in decreased mortality in both gonadectomized males and females. These results demonstrate that estrogen is providing protection against V. vulnificus lipopolysaccharide-induced endotoxic shock.

Animals↗
PubMed2000

Glycoprotein folding in the endoplasmic reticulum: a tale of three chaperones?

The endoplasmic reticulum (ER) is a major site of protein synthesis and its inside, or lumen, is a major site of protein folding. The lumen of the ER contains many folding factors and molecular chaperones, which facilitate protein folding by increasing both the rate and the efficiency of this process. Amongst the many ER folding factors, there are three components that specifically modulate the folding glycoproteins bearing N-linked carbohydrate side chains. These components are calnexin, calreticulin and ERp57, and this review focuses on the molecular basis for their capacity to influence glycoprotein folding.

Animals↗
PubMed2000

Renal sarcoidosis with superimposed postinfectious glomerulonephritis presenting as acute renal failure.

We describe two patients with sarcoidosis with lesions of granulomatous interstitial nephritis (GIN) and postinfectious glomerulonephritis (GN). Both patients presented with heavy proteinuria, hematuria, and renal failure. Renal histology in both showed GIN and glomerular changes of proliferative GN with hump-like subepithelial deposits by electron microscopy of postinfectious GN. Antecedent history of pneumonia was present in one, and ASO titer was elevated in the other. The proteinuria and azotemia improved in both with steroid therapy. Reports of "postinfectious" or diffuse proliferative GN in patients with sarcoidosis are rare. The authors are unaware of reports of concomitant sarcoid GIN and postinfectious GN. Although acute renal insufficiency or failure can occur with GIN or other more common renal lesions primary glomerular disease should be considered in patients with sarcoidosis who present with renal dysfunction. This is a US government work. There are no restrictions on its use.

Acute Kidney Injury↗
PubMed2000

Effect of starvation and the viable-but-nonculturable state on green fluorescent protein (GFP) fluorescence in GFP-tagged Pseudomonas fluorescens A506.

The green fluorescent protein (GFP) gene, gfp, of the jellyfish Aequorea victoria is being used as a reporter system for gene expression and as a marker for tracking prokaryotes and eukaryotes. Cells that have been genetically altered with the gfp gene produce a protein that fluoresces when it is excited by UV light. This unique phenotype allows gfp-tagged cells to be specifically monitored by nondestructive means. In this study we determined whether a gfp-tagged strain of Pseudomonas fluorescens continued to fluoresce under conditions under which the cells were starved, viable but nonculturable (VBNC), or dead. Epifluorescent microscopy, flow cytometry, and spectrofluorometry were used to measure fluorescence intensity in starved, VBNC, and dead or dying cells. Results obtained by using flow cytometry indicated that microcosms containing VBNC cells, which were obtained by incubation under stress conditions (starvation at 37.5 degrees C), fluoresced at an intensity that was at least 80% of the intensity of nonstressed cultures. Similarly, microcosms containing starved cells incubated at 5 and 30 degrees C had fluorescence intensities that were 90 to 110% of the intensity of nonstressed cells. VBNC cells remained fluorescent during the entire 6-month incubation period. In addition, cells starved at 5 or 30 degrees C remained fluorescent for at least 11 months. Treatment of the cells with UV light or incubation at 39 or 50 degrees C resulted in a loss of GFP from the cells. There was a strong correlation between cell death and leakage of GFP from the cells, although the extent of leakage varied depending on the treatment. Most dead cells were not GFP fluorescent, but a small proportion of the dead cells retained some GFP at a lower concentration than the concentration in live cells. Our results suggest that gfp-tagged cells remain fluorescent following starvation and entry into the VBNC state but that fluorescence is lost when the cells die, presumably because membrane integrity is lost.

Colony Count, Microbial↗
PubMed1999

Pathogenesis of Vibrio vulnificus.

This review describes the factors which are currently recognized as being central to the virulence of the human pathogen, Vibrio vulnificus. This estuarine/marine bacterium occurs in high numbers in molluscan shellfish, primarily oysters, and its ingestion in raw oysters results in a ca. 60% mortality in those persons who are susceptible to this bacterium. The organism is also able to produce life-threatening wound infections. We describe here the nature of both the wound and primary septicemia infections, the virulence factors known or believed to be involved in these infections, possible immunotherapy, and some thoughts on the possibility that not all strains of this pathogen are virulent.

Bacteremia↗
PubMed1999

ERp57 functions as a subunit of specific complexes formed with the ER lectins calreticulin and calnexin.

ERp57 is a lumenal protein of the endoplasmic reticulum (ER) and a member of the protein disulfide isomerase (PDI) family. In contrast to archetypal PDI, ERp57 interacts specifically with newly synthesized glycoproteins. In this study we demonstrate that ERp57 forms discrete complexes with the ER lectins, calnexin and calreticulin. Specific ERp57/calreticulin complexes exist in canine pancreatic microsomes, as demonstrated by SDS-PAGE after cross-linking, and by native electrophoresis in the absence of cross-linking. After in vitro translation and import into microsomes, radiolabeled ERp57 can be cross-linked to endogenous calreticulin and calnexin while radiolabeled PDI cannot. Likewise, radiolabeled calreticulin is cross-linked to endogenous ERp57 but not PDI. Similar results were obtained in Lec23 cells, which lack the glucosidase I necessary to produce glycoprotein substrates capable of binding to calnexin and calreticulin. This observation indicates that ERp57 interacts with both of the ER lectins in the absence of their glycoprotein substrate. This result was confirmed by a specific interaction between in vitro synthesized calreticulin and ERp57 prepared in solution in the absence of other ER components. We conclude that ERp57 forms complexes with both calnexin and calreticulin and propose that it is these complexes that can specifically modulate glycoprotein folding within the ER lumen.

Animals↗
PubMed1999

The structures of alpha 2u-globulin and its complex with a hyaline droplet inducer.

Alpha 2u-globulin (A2U) is the major urinary protein excreted by adult male rats. The structure of a monoclinic crystal form of A2U was reported in 1992 [Böcskei et al. (1992). Nature (London), 360, 186-188]. The structures of an orthorhombic crystal form of A2U at 2. 5 A resolution (refined to an R factor of 0.248; Rfree = 0.264) and of a complex between A2U and d-limonene 1,2-epoxide (DLO) at 2.9 A resolution (R factor = 0.248; Rfree = 0.260) are presented here. DLO is one of a diverse group of chemicals which cause a male rat-specific renal carcinogenesis called hyaline-droplet nephropathy. The rate-determining step in the development of this disorder is the binding of the toxin to A2U. Comparison of the cavities in A2U and in the corresponding mouse urinary protein (MUP) reveal that the former is tailor-made for small oval hydrophobic ligands such as DLO. The cavity in MUP is more shallow and elongated and cannot easily accommodate such ligands.

Alpha-Globulins↗
PubMed1999

Comparative study of biological properties and electrophoretic characteristics of lipopolysaccharide from eel-virulent and eel-A virulent Vibrio vulnificus strains.

In Vibrio vulnificus, virulence for eels is associated with serovar E strains. In this study, we investigated some biological properties of purified lipopolysaccharides (LPSs) from serovar E and non-serovar E strains. Purified LPSs retained their O-polysaccharidic side chains and did not show any differences that could be related to host specificity, except for serological differences.

Animals↗
PubMed1999

Randomly amplified polymorphic DNA analysis of clinical and environmental isolates of Vibrio vulnificus and other vibrio species.

Vibrio vulnificus is an estuarine bacterium that is capable of causing a rapidly fatal infection in humans. A randomly amplified polymorphic DNA (RAPD) PCR protocol was developed for use in detecting V. vulnificus, as well as other members of the genus Vibrio. The resulting RAPD profiles were analyzed by using RFLPScan software. This RAPD method clearly differentiated between members of the genus Vibrio and between isolates of V. vulnificus. Each V. vulnificus strain produced a unique band pattern, indicating that the members of this species are genetically quite heterogeneous. All of the vibrios were found to have amplification products whose sizes were within four common molecular weight ranges, while the V. vulnificus strains had an additional two molecular weight range bands in common. All of the V. vulnificus strains isolated from clinical specimens produced an additional band that was only occasionally found in environmental strains; this suggests that, as is the case with the Kanagawa hemolysin of Vibrio parahaemolyticus, the presence of this band may be correlated with the ability of a strain to produce an infection in humans. In addition, band pattern differences were observed between encapsulated and nonencapsulated isogenic morphotypes of the same strain of V. vulnificus.

Bacterial Typing Techniques↗
PubMed1998

The transient association of ERp57 with N-glycosylated proteins is regulated by glucose trimming.

The thiol-dependent reductase ERp57 has been shown to interact specifically with in vitro synthesised glycoproteins imported into canine pancreatic microsomes. On this basis, it was proposed that ERp57 forms part of a glycoprotein-specific folding 'machinery', present in the lumen of the endoplasmic reticulum (ER). In this study, we have investigated the interaction of ERp57 with newly synthesised proteins using semi-permeabilised mammalian cells (SP cells), in which the ER remains essentially intact and, hence, resembles that of a living cell. We demonstrate that ERp57 interacts preferentially with the glycosylated versions of soluble and membrane proteins, and that this interaction occurs in combination with calnexin and calreticulin. For the first time, we have performed a detailed analysis of the kinetics of ERp57 binding to newly synthesised glycoproteins. We find that ERp57 associates transiently with glycoproteins - a characteristic of molecular chaperones. Using mutant SP cells deficient in glucosidase I, we confirm that the binding of ERp57 to glycoproteins depends upon glucose trimming. We also demonstrate, for the first time, that the release of ERp57 from glycoprotein substrates is dependent upon glucose trimming. These data are combined to present a unified model for the role of ERp57/ER lectin complexes during glycoprotein folding in vivo.

Animals↗