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Biomedical subjects

D R Scholl

Publications and source records attributed to D R Scholl.

10 recordsLinked to original sources
PubMed1990

Herpes simplex virus resistant to acyclovir. A study in a tertiary care center.

STUDY OBJECTIVE: To determine the sensitivity of herpes simplex virus isolates to acyclovir and the importance of resistant isolates in hospitalized patients. DESIGN: Retrospective incidence cohort study. SETTING: All herpes simplex virus isolates cultured over 1 year from patients followed at a tertiary care center. PATIENTS: Consecutive herpes simplex virus isolates were collected from 207 patients, including immunocompetent patients, patients with malignancy, neonates, bone marrow and organ transplant recipients, and patients seropositive for human immunodeficiency virus. MEASUREMENTS AND MAIN RESULTS: A rapid nucleic acid hybridization method was used to assess susceptibility to acyclovir. Acyclovir-resistant herpes simplex viruses were recovered from 7 of 148 immunocompromised patients (4.7%) but from none of 59 immunocompetent hosts. Clinical disease was found in all 7 patients with resistant herpes simplex virus and was more severe in pediatric patients. All resistant isolates were from acyclovir-treated patients and had absent or altered thymidine kinase activity by plaque autoradiography. CONCLUSION: Herpes simplex virus resistant to acyclovir arises relatively frequently in immunocompromised patients and may cause serious disease. Rapid detection of resistance permits antiviral therapy to be individualized. Antiviral susceptibility testing to monitor viral resistance should be encouraged, especially in tertiary care settings.

Acyclovir↗
PubMed1990

Clinical application of novel sample processing technology for the identification of salmonellae by using DNA probes.

Two hundred and fifty clinical fecal specimens collected over a 7-month period were analyzed for the presence of salmonellae by a rapid DNA hybridization procedure. Hybridizations were performed by using a novel specimen processing protocol called wicking and a previously unreported 1,600-base-pair probe cloned from Salmonella enteritidis DNA. The probe was shown to be reactive with all 70 Salmonella serotypes tested and not reactive with 101 stock strains of other enteric bacteria. Southern analysis of 30 Salmonella isolates representing 22 serotypes suggested that the probe sequence was highly conserved, appearing as a 1,600-base-pair band in a BglII digest of isolate DNA in 29 of 30 isolates and as a 2,300-base-pair fragment in 1 of the isolates. The probe correctly identified all salmonellae (nine isolates) among 47 H2S-producing colonies tested from among 250 clinical specimens cultured on xylose-lysine-desoxycholate medium. Salmonellae grown on xylose-lysine-desoxycholate medium gave consistently higher hybridization values than did those grown on either MacConkey or Hektoen enteric agar. In addition, of eight gram-negative broth enrichments in which salmonellae were identified by conventional means, seven were probe positive. The use of this nucleic acid probe and hybridization technique provides a simple and rapid identification of Salmonella species.

Bacteriological Techniques↗
PubMed1989

Method for improved extraction of DNA from Nocardia asteroides.

In a variation of standard DNA extraction methods, Nocardia asteroides was repeatedly exposed to sodium dodecyl sulfate at 60 degrees C for 30 min; each extraction was followed by centrifugation, removal of the nucleic acid-rich supernatant, and suspension of the cell pellet in fresh sodium dodecyl sulfate. The pooled supernatants contained a substantially higher amount of DNA than the first supernatant alone. The possible implications of this procedure on the development of DNA probes are discussed.

DNA Probes↗
PubMed1987

Improved DNA hybridization method for detection of acyclovir-resistant herpes simplex virus.

A simplified DNA hybridization method was developed to detect acyclovir-resistant isolates of herpes simplex virus. Herpes simplex virus-infected cell cultures in microtiter plates were treated with concentrations of acyclovir ranging from 8 to 0.015 micrograms/ml. At 48 h postinfection, infected cells were lysed by a one-step procedure and lysates were absorbed to membranes. Without further treatment, membranes were hybridized by using a herpes simplex virus-specific radioiodinated probe. The membranes were then washed and counted in a gamma counter. The elapsed time for assay performance was 4 h. Parallel plaque reduction assays were performed for comparison. The mean 50% inhibitory dose of in vivo- and in vitro-derived acyclovir-resistant, thymidine kinase-negative isolates was greater than 2 micrograms/ml by DNA hybridization. The 50% inhibitory dose of acyclovir-susceptible, thymidine kinase-positive isolates ranged from 0.01 to 1.1 micrograms/ml. This assay is simple and objective and should facilitate antiviral susceptibility testing in diagnostic laboratories.

Acyclovir↗
PubMed1984

Characterization of a solitary long terminal repeat of avian endogenous virus origin.

A recombinant lambda phage library constructed with a partial EcoR1 digest of DNA from a normal RPRL line 15B chicken was screened using 32P-labeled plasmid containing Rous-associated virus (pRAV-2). Nucleotide sequence analyses of a fragment of one subclone revealed the presence of a solitary long terminal repeat (LTR) that is similar to the LTRs of avian endogenous retroviruses ev1 and ev2. This LTR is flanked by unique 6 bp direct repeats characteristic of the target site for duplication of avian leukosis viruses.

Animals↗
PubMed1983

Nucleotide sequence of the long terminal repeat and flanking cellular sequences of avian endogenous retrovirus ev-2: variation in Rous-associated virus-0 expression cannot be explained by differences in primary sequence.

A fragment of chicken DNA containing the left long terminal repeat of endogenous retrovirus ev-2 and flanking cellular sequences has been molecularly cloned and analyzed. Comparison with sequence data from the analogous regions of ev-1 and Rous-associated virus-0 viral DNA reveals similarities among flanking regions of the integrated proviruses and among all three long terminal repeats. From the latter finding, we conclude that the difference in level of expression of ev-2 and its progeny Rous-associated virus-0 provirus cannot be due to sequence differences in their upstream long terminal repeats.

Animals↗
PubMed1981

Microinjection of a rabbit beta-globin gene into zygotes and its subsequent expression in adult mice and their offspring.

We have transferred a gene coding for rabbit beta-globin into the male pronucleus of mouse zygotes by direct microinjection. Some of these zygotes developed into mature mice which contained this gene and appeared to be producing a rabbit globin. Evidence for the presence of the gene in these animals was provided by Southern blot hybridization analysis. Evidence for the expression of the rabbit gene in these transformed mice and their offspring was provided by hemoglobin isoelectric focusing analysis and specific serological reactivity between mouse anti-rabbit hemoglobin antiserum and a hemolysate from the mice that developed from the microinjected zygotes. The use of this zygote transformation may allow the introduction and expression of a broad range of genetic elements in mammals.

Animals↗
PubMed1980

Pilus-dependent, double-stranded DNA bacteriophage for Caulobacter.

Caulobacter phage phi 6, previously reported to adsorb specifically to bacterial flagella, was shown here to attach to pili more frequently than to flagella. Phage phi 6 was shown to contain double-stranded DNA by circular dichroism spectroscopy and thermal denaturation accompanied by a hyperchromic shift at 260 nm. Morphologically, phage phi 6 fits group B2 (H.-W. Ackermann, in A. I. Laskin and H. A. Lechevalier, ed., Handbook of Microbiology, vol. 1, p. 638-643, 1973) with a long, noncontractile tail and an elongate head. Pilus-less mutants of the host Caulobacter vibrioides CV6 are phage phi 6 resistant, whereas flagellum-less mutants, which produce pili, are phage susceptible. Treatments of susceptible cells which remove or immobilize pili and flagella, e.g., blending or cyanide, inhibited phage phi 6 infection. Our evidence suggests that phage of phi 6 initiates infection in a manner similar to the pilus-specific phages for Pseudomonas described previously (D. E. Bradley, Virology 51:489-492, 1973; D. E. Bradley and T. L. Pitt, J. Gen. Virol. 24:1-15, 1974).

Bacteria↗
PubMedDate not supplied

Cloning of a partial length cDNA encoding the C-terminal portion of the 75-77-kDa antigen of Trypanosoma cruzi.

It has been suggested that several Trypanosoma cruzi antigens have possible protective epitopes which may be suitable vaccine candidates. We found previously that animals resistant to T. cruzi infection produced antibodies against the 75-77-kDa parasite antigen. To test the ability of the recombinant form of this antigen to protect animals from T. cruzi infection, the cDNA which encodes a portion of the 75-77-kDa antigen was cloned using a cDNA library constructed in an orientation-specific bacteriophage expression vector (lambda gt 11) from poly (A)+ RNA of Brazil strain epimastigotes. One clone, named SFS-40, was selected by screening the library using affinity purified antibodies specific for the 75-77-kDa parasite antigen as probe. The cDNA corresponding to the 1.7-kilobase insert of SFS-40 was subcloned into plasmid vectors and characterized. The cDNA sequence encodes a polypeptide of about 40 kDa. The putative product of the cDNA was homologous to members of the 70-kDa stress protein family. When epimastigotes were shifted from 29 degrees C to 37 degrees C, there was no change in the level of SFS-40 mRNA. In contrast, the 70-kDa heat shock protein mRNA of the parasite was increased about four fold by this treatment.

Amino Acid Sequence↗