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Biomedical subjects

J A Giron

Publications and source records attributed to J A Giron.

15 recordsLinked to original sources
PubMed1995

Interplay between mycoplasmas and host target cells.

The infectious pattern of mycoplasmas (Mycoplasma penetrans, Mycoplasma pneumoniae and Mycoplasma genitalium) in mammalian cells was examined using confocal microscopy and flow cytometry combined with cell fractionation and mycoplasma viability determinations. Within 2 h postinfection mycoplasmas parasitize cell surfaces, enter the intracellular spaces and locate throughout the cytoplasmic and perinuclear regions. These mycoplasmas can be cultivated from cytoplasmic and nuclear fractions 96 h later and continue to persist intracellularly for at least 7 days, suggesting a much more active intracellular role for mycoplasmas than had been considered previously.

Animals↗
PubMed1993

Aggregative adherence fimbria I expression in enteroaggregative Escherichia coli requires two unlinked plasmid regions.

Adherence to HEp-2 cells by many enteroaggregative Escherichia coli (EAggEC) strains is associated with the expression of flexible, bundle-forming fimbriae 2 to 3 nm in diameter, designated aggregative adherence fimbriae I (AAF/I). We have previously reported the molecular cloning and TnphoA mutagenesis of AAF/I genes from the large plasmid of prototype EAggEC strain 17-2 (J. P. Nataro, Y. Deng, D. R. Maneval, A. L. German, W. C. Martin, and M. M. Levine, Infect. Immun. 60:2297-2304, 1992). Here, we report that further mapping and subcloning of AAF/I regions suggest that expression of the fimbriae requires two separate plasmid regions (designated regions 1 and 2). Approximately 9 kb of DNA unnecessary for fimbrial expression separates the two regions; this intervening segment encodes the EAggEC heat-stable enterotoxin (EAST1). Neither region was capable of conferring aggregative HEp-2 adherence (AA) when cloned individually; when the two regions were cloned as a single fragment or when each was cloned into a different vector and introduced into the same E. coli HB101 cell, AA was restored. AA-positive constructs also expressed human erythrocyte hemagglutination, autoagglutination in broth cultures, and the production of AAF/I as detected by immunogold electron microscopy.

Amino Acid Sequence↗
PubMed1990

Detection of Shigella in feces using DNA amplification.

A rapid diagnostic method employing a polymerase chain reaction procedure (PCR) was used to identify Shigella and enteroinvasive Escherichia coli. This procedure amplified a region of the invasive-associated locus (ial) from a crude DNA extract of feces. A synthetic 21-base oligonucleotide corresponding to the ial gene sequence was shown to specifically hybridize only with enteroinvasive E. coli (EIEC) strains and Shigella species. Upon PCR amplification, a 320-base pair fragment was generated in DNA extracted from feces reconstituted with EIEC or Shigella flexneri but not in DNA from 70 normal stools lacking these organisms and could be readily detected by the ial probe. For identifying Shigella and EIEC, the PCR assay was 10(5)- and 10(2)-fold more sensitive than standard biochemical tests and the macrocolony hybridization assay, respectively. These findings demonstrate a novel methodology for rapid, sensitive, and culture-independent diagnosis of diarrhea caused by these pathogens and underscores the utility of PCR in the diagnostic laboratory.

Base Sequence↗
PubMed1989

Multi-gene amplification: simultaneous detection of three virulence genes in diarrhoeal stool.

Enterotoxigenic Escherichia coli (ETEC) and Shigella account for a substantial proportion of acute diarrhoeal illnesses among Third-World children. Rapid detection of these infectious agents in faeces followed by the prompt implementation of public health measures could help reduce their spread during the early phase of epidemics. Towards this end, three pairs of synthetic oligonucleotide primers were prepared and shown to hybridize specifically to the genes encoding the heat-stable (ST) and the heat-labile (LT) enterotoxins of ETEC and to invasion-associated loci (ial) of the large Shigella virulence plasmid. When the three primer pairs were used together in the polymerase chain reaction (PCR), the three corresponding genetic loci could be simultaneously amplified using DNA extracted directly from stool; the amplified products were readily detected by ST-, LT- and ial-specific, alkaline phosphatase-labelled oligonucleotide probes (AP probes). The performance of this system was evaluated in a Mayan community in southeastern Mexico, where diarrhoeal illnesses are a common cause of childhood morbidity and mortality. Using only simple and inexpensive laboratory equipment, multigene amplification with these primers and probes led to the identification of ETEC and/or Shigella in the stools of 20 out of 71 children with diarrhoea; the procedure could be completed in seven hours and was more sensitive than conventional diagnostic tests or DNA probes used without amplification.

Base Sequence↗
PubMed1986

Prevalence of antibodies to HTLV-I, -II, and -III in intravenous drug abusers from an AIDS endemic region.

Antibody prevalences for human T-cell lymphotropic virus (HTLV) types I, II, and III were determined for 56 intravenous drug abusers from Queens, NY. While control serum samples lacked antibodies to all HTLV subgroups, seropositivity among drug users was 41% for HTLV-III, 18% for HTLV-II, and 9% for HTLV-I. Infection by HTLV-I and -II occurred independently of HTLV-III infection. Blacks had greater HTLV-III antibody prevalence than whites (54% vs 16%) and were more likely than whites to be seropositive for HTLV-I or -II (46% vs 11%). They exhibited a greater incidence than whites of double infection with HTLV-I or -II and HTLV-III (27% vs 0%), and 73% were seropositive for at least one of the viruses, compared with only 26% of the whites. The increased HTLV-I and -II infection seen in intravenous drug users suggests that once introduced into a population, these viruses may be transmitted by the same routes as HTLV-III. Transmission may have been restricted mainly to blacks in this study because of local drug use practices.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Serological evidence for simultaneous occurrences of Lyme disease and babesiosis.

Babesia microti and Borrelia burgdorferi, the spirochetal agent of Lyme disease, are both transmitted by the tick Ixodes dammini. Serological evidence has shown that 54% of the patients with babesiosis tested have IgG and IgM antibodies to the spirochete causing Lyme disease. Likewise, 66% of randomly selected patients with Lyme disease from geographic areas endemic for both diseases, but not from areas where babesiosis does not occur, also have IgM and IgG antibodies to B. microti. Antigenic cross-reactivity is not the reason for these findings, as laboratory animals experimentally infected with B. microti do not develop antibodies to B. burgdorferi, and laboratory animals immunized with organisms derived from pure cultures of spirochetes do not develop antibodies to B. microti. We suggest that these patients are concurrently exposed to both organisms by doubly infected tick vectors.

Animals↗
PubMed1984

Soft tissue infections in parenteral drug abusers.

Thirty-four parenteral drug abusers admitted with soft tissue infections underwent bacteriologic and immunologic evaluation. Staphylococcus aureus and beta hemolytic streptococci were the most common organisms recovered. Enteric gram negative aerobes and oral flora were common and enteric anaerobes rare. Absolute lymphopenia and elevations in the IgA, IgG and IgM fractions of the immunoglobulins were common as were false positive VDRL examinations. Cutaneous anergy was found in 83% of the group and 70% of a simultaneously noninfected addict group. Staphylococcal carriage was frequent. Because of variation in the flora between this and other reported groups, ongoing bacteriologic surveillance could be a useful guide to initial antibiotic therapy. Differences in the pattern of immune reaction in this group when compared to different addict groups suggest a difference in antigenic stimulation, possibly as a result of differences in bacteriologic exposure.

Abscess↗
PubMed1983

Infections in parenteral drug abusers. Further immunologic studies.

In our previous study of soft tissue infections in parenteral drug abusers, two thirds of the infections were polymicrobial. Oral and enteric organisms were frequently recovered. These patients and a group of uninfected addicts showed frequent cutaneous anergy, lymphopenia, and hypergammaglobulinemia. An additional group of uninfected addicts was studied. The mean levels of IgA, IgG, and IgM were higher in the uninfected addicts. In the addict and control groups, elevations in IgA (17 percent of total), IgG (65 percent), and IgM (19 percent) levels were found. Zinc levels were within normal limits. T-cell populations below 70 percent were seen in five of the seven addicts and two of the four control subjects. Reversed helper to suppressor cell ratios were found in three of the seven addicts and control subjects. No consistent pattern of immunologic abnormalities emerged. The interrelationship of the abnormalities in the addict and their relationship to AIDS is unclear.

B-Lymphocytes↗
PubMed1981

Pharmacokinetics of piperacillin in patients with moderate renal failure and in patients undergoing hemodialysis.

The pharmacokinetics of piperacillin administered intravenously were studied in five patients with stable mild to moderate renal impairment and in five patients undergoing hemodialysis. Patients with stable renal failure given 1 g of piperacillin intravenously had peak serum concentrations within 30 min ranging from 78 to 280 micrograms/ml. The mean serum half-life was 3.57 +/- 1.36 h; the mean apparent volume of distribution was 28.6 +/- 13.5 liters/100 kg; and the plasma clearance was 4.10 +/- 1.46 liters/h per 1.73 m2. Neither serum half-life nor clearance correlated with serum creatinine, implying significant nonrenal elimination. Patients undergoing hemodialysis had peak serum concentrations within 30 min of 66 to 138 micrograms/ml after 1 g of piperacillin infused intravenously. During hemodialysis, the serum half-life was 3.6 +/- 2.5 h; the mean apparent volume of distribution was 26.7 +/- 16.7 liters/100 kg; and the plasma clearance was 3.28 +/- 0.76 layers/h per 1.73 m2. Mean hemodialysis clearance was 0.484 +/- 0.282 liters/h per 1.73 m2, and only 10.0 +/- 5.3% of the total dose could be recovered in the dialysate.

Adult↗
PubMed1981

Biliary concentrations of piperacillin in patients undergoing cholecystectomy.

Piperacillin is a new semisynthetic, expanded-spectrum penicillin with marked activity against Pseudomonas aeruginosa. The biliary excretion of piperacillin was studied in patients undergoing cholecystectomy. Concentrations of piperacillin in common duct bile at 35 to 90 min postinfusion of 1-g doses ranged from 31 to 920 micrograms/ml, with a mean (+/- standard deviation) of 467 +/- 363 micrograms/ml. Gallbladder piperacillin levels at 30 to 75 min postinfusion ranged from 2.2 to 80 micrograms/ml, with a mean of 27 +/- 31 micrograms/ml. No correlation occurred with peak serum level of antibiotic, creatinine, bilirubin, or alkaline phosphatase. Significant amounts of piperacillin were excreted via the biliary system.

Bile↗