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Biomedical subjects

R Shafer

Publications and source records attributed to R Shafer.

At least 19 recordsLinked to original sources
PubMed2001

Comparison of IsoCode STIX and FTA Gene Guard collection matrices as whole-blood storage and processing devices for diagnosis of malaria by PCR.

We compared two collection devices, IsoCode and FTA, with whole blood for the diagnosis of malaria by PCR (n = 100). Using whole blood as the reference standard, both devices were sensitive for the detection of single-species malaria infections by PCR (> or =96%). However, the detection of mixed infections was suboptimal (IsoCode was 42% sensitive, and FTA was 63% sensitive).

Animals↗
PubMed2001

Malaria rapid diagnostic devices: performance characteristics of the ParaSight F device determined in a multisite field study.

Microscopic detection of parasites has been the reference standard for malaria diagnosis for decades. However, difficulty in maintaining required technical skills and infrastructure has spurred the development of several nonmicroscopic malaria rapid diagnostic devices based on the detection of malaria parasite antigen in whole blood. The ParaSight F test is one such device. It detects the presence of Plasmodium falciparum-specific histidine-rich protein 2 by using an antigen-capture immunochromatographic strip format. The present study was conducted at outpatient malaria clinics in Iquitos, Peru, and Maesod, Thailand. Duplicate, blinded, expert microscopy was employed as the reference standard for evaluating device performance. Of 2,988 eligible patients, microscopy showed that 547 (18%) had P. falciparum, 658 (22%) had P. vivax, 2 (0.07%) had P. malariae, and 1,750 (59%) were negative for Plasmodium. Mixed infections (P. falciparum and P. vivax) were identified in 31 patients (1%). The overall sensitivity of ParaSight F for P. falciparum was 95%. When stratified by magnitude of parasitemia (no. of asexual parasites per microliter of whole blood), sensitivities were 83% (>0 to 500 parasites/microl), 87% (501 to 1,000/microl), 98% (1,001 to 5,000/microl), and 98% (>5,000/microl). Device specificity was 86%.

Animals↗
PubMed1999

ACTG 260: a randomized, phase I-II, dose-ranging trial of the anti-human immunodeficiency virus activity of delavirdine monotherapy. The AIDS Clinical Trials Group Protocol 260 Team.

ACTG 260 was an open-label, four-arm trial designed to study the safety and anti-human immunodeficiency virus (anti-HIV) activity of delavirdine monotherapy at three ranges of concentrations in plasma compared to those of control therapy with zidovudine or didanosine. Delavirdine doses were adjusted weekly until subjects were within their target trough concentration range (3 to 10, 11 to 30, or 31 to 50 microM). A total of 113 subjects were analyzed. At week 2, the mean HIV type 1 (HIV-1) RNA level declines among the subjects in the three delavirdine arms were similar (0.87, 1.08, and 1.02 log10 for the low, middle, and high target arms, respectively), but by week 8, the subjects in the pooled delavirdine arms showed only a 0.10 log10 reduction. In the subjects in the nucleoside arm, mean HIV-1 RNA level reductions at weeks 2 and 8 were 0.67 and 0.55 log10, respectively. Because viral suppression by delavirdine was not maintained, the trial was stopped early. Rash, which was usually self-limited, developed in 36% of subjects who received delavirdine. Delavirdine monotherapy has potent anti-HIV activity at 2 weeks, but its activity is time limited due to the rapid emergence of drug resistance.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Interlaboratory concordance of DNA sequence analysis to detect reverse transcriptase mutations in HIV-1 proviral DNA. ACTG Sequencing Working Group. AIDS Clinical Trials Group.

Thirteen laboratories evaluated the reproducibility of sequencing methods to detect drug resistance mutations in HIV-1 reverse transcriptase (RT). Blinded, cultured peripheral blood mononuclear cell pellets were distributed to each laboratory. Each laboratory used its preferred method for sequencing proviral DNA. Differences in protocols included: DNA purification; number of PCR amplifications; PCR product purification; sequence/location of PCR/sequencing primers; sequencing template; sequencing reaction label; sequencing polymerase; and use of manual versus automated methods to resolve sequencing reaction products. Five unknowns were evaluated. Thirteen laboratories submitted 39043 nucleotide assignments spanning codons 10-256 of HIV-1 RT. A consensus nucleotide assignment (defined as agreement among > or = 75% of laboratories) could be made in over 99% of nucleotide positions, and was more frequent in the three laboratory isolates. The overall rate of discrepant nucleotide assignments was 0.29%. A consensus nucleotide assignment could not be made at RT codon 41 in the clinical isolate tested. Clonal analysis revealed that this was due to the presence of a mixture of wild-type and mutant genotypes. These observations suggest that sequencing methodologies currently in use in ACTG laboratories to sequence HIV-1 RT yield highly concordant results for laboratory strains; however, more discrepancies among laboratories may occur when clinical isolates are tested.

Codon↗
PubMed1998

Principal findings from the Washington State cognitive services demonstration project.

In addition to dispensing, pharmacists are ideally positioned to provide cognitive services that are targeted at optimizing drug therapy through identification and resolution of drug therapy problems. The Washington Cognitive Activities and Reimbursement Effectiveness project sought to determine: (1) if pharmacists would respond to a financial incentive by performing more cognitive services, and (2) the effect on drug cost of cognitive services they performed.

Attitude of Health Personnel↗
PubMed1998

When the morning after is Sunday: pharmacist prescribing of emergency contraceptive pills.

Pharmacists are well positioned to play a major role in increasing access to emergency contraceptive pills (ECPs). A pilot project in Washington State is testing direct pharmacist prescribing. Through a collaborative drug therapy agreement, a licensed prescriber, such as a physician, delegates to a pharmacist the authority to prescribe ECPs directly to women who meet the assessment criteria. Currently pharmacists at 111 Washington State pharmacies have collaborative agreements in place, and the number of participating pharmacies continues to increase. The response to this initiative has been extremely positive. Women who have received ECPs directly from pharmacists rate their interactions with the pharmacists positively and overwhelmingly cite convenience as the primary reason for going directly to the pharmacy. Physicians and other providers with independent prescribing authority can play a pivotal role by working with pharmacists to replicate the Washington State initiative in the states that allow it.

Contraceptives, Postcoital↗
PubMed1993

Nuclear magnetic resonance comparison of the binding sites of mithramycin and chromomycin on the self-complementary oligonucleotide d(ACCCGGGT)2. Evidence that the saccharide chains have a role in sequence specificity.

A comprehensive two-dimensional 1H nuclear magnetic resonance spectral analysis of the ternary 4:2:1 mithramycin-Mg2+-d(A1C2C3C4G5G6G7T8)2 complex and the ternary 2:1:1 chromomycin-Mg(2+)-d(A21C2C3C4C4G5G6G7T8)2 complex is presented. The self-complementary oligonucleotide is found to bind two dimers of mithramycin in two identical off-center binding sites such that the twofold symmetry of the oligonucleotide is retained. In contrast, the same oligonucleotide binds only one dimer of chromomycin in a single but distinct off-center binding site. Two-dimensional nuclear Overhauser spectroscopy experiments show that the aglycone binding site of the drug dimer in each complex extends over almost four base-pairs and is similar in length to other complexes between chromomycin or mithramycin and oligonucleotides. The data demonstrate that the chromomycin dimer binding site is offset by one base-pair step from the dimer binding site in the mithramycin complex. This preferred binding site prevents two dimers of chromomycin binding to d(ACCCGGGT)2 for steric reasons and lends further support to previous work that showed the 5'-CG base-pair site is less favored by these drugs compared to the 5'GC and 5'-GG,5'-CC sites. Evidence is presented that suggests mithramycin may occupy either of two distinct binding sites on d(ACCCGGGT)2 when the drug concentration is not saturating. The nuclear magnetic resonance data demonstrate that the saccharide chains of this family of drugs do have a role in determining the binding site on nucleotides and as a consequence the CDE trisaccharide chain may alter its conformation to fulfil this role. Titration of mithramycin up to a drug-duplex ratio of 7:1 reveals further association of mithramycin with the complex but no new drug-oligonucleotide nuclear Overhauser enhancement contacts.

Binding Sites↗
PubMed1993

Measurement of HIV virus load and genotypic resistance by gene amplification in asymptomatic subjects treated with combination therapy.

Quantification of viral load in HIV disease has become increasingly important as a marker of antiviral efficacy. We applied gene amplification techniques in vivo to asses antiretroviral activity of combination therapy. Five HIV-infected subjects, four of whom were drug naive, were administered combination therapy with zidovudine (ZDV) and didanosine (ddI). Plasma and peripheral blood mononuclear cells (PBMC) were obtained twice at baseline and then at 1, 3, 6, 9, and 12 months after the initiation of therapy. Results show that plasma HIV RNA copy number fell from 2,170 +/- 660/ml to undetectable at 1 month, with continued suppression at 12 months. HIV proviral DNA copy number decreased from 3.9 to 3.0 log10/10(6) CD4+ T cells at 12 months. Cell dilution cultures were positive in 4 of 5 subjects at baseline and in only 1 of 5 after 12 months. CD4+ T-cell count increased from 390 +/- 30/mm3 pretherapy, to 505 +/- 66/mm3 after 6 months of therapy, but returned to baseline levels after 12 months of therapy. No mutations were detected from PBMC DNA for codon 215 and 74 in the HIV pol gene from the drug-naive subjects. These findings suggest that gene amplification techniques can be used to study changes in viral load or genotype and can be applied in real time to samples from patients involved in clinical trials.

CD4-Positive T-Lymphocytes↗
PubMed1989

A combined 2D-NMR and molecular dynamics analysis of the structure of the actinomycin D: d(ATGCAT)2 complex.

We present a comparative analysis of an NMR experiment and molecular and harmonic dynamics simulations of an actinomycin D: d(ATGCAT)2 complex. A comparison of NOE measurements and 1/R6 weighted proton-proton distances confirm the general correctness of the Actinomycin D-DNA model proposed by Sobell. There are, however, some substantial differences between the proton-proton distances inferred from the NOE results and the molecular and harmonic dynamics simulations. The remaining discrepancies could either come from contributions of other conformations to the average properties of the complex or from uncertainties in the NMR distance analysis. An analysis of the molecular dynamics helix properties, sugar puckers, hydrogen bonding, rms fluctuations and torsional properties are qualitatively consistent with those from previous simulations, but the presence of an intercalated drug leads to some new structural and dynamical features.

Chemical Phenomena↗
PubMed1987

Exercise thallium testing in ventricular preexcitation.

Ventricular preexcitation, as seen in Wolff-Parkinson-White syndrome, results in a high frequency of positive exercise electrocardiographic responses. Why this occurs is unknown but is not believed to reflect myocardial ischemia. Exercise thallium testing is often used for noninvasive assessment of coronary artery disease in patients with conditions known to result in false-positive electrocardiographic responses. To assess the effects of ventricular preexcitation on exercise thallium testing, 8 men (aged 42 +/- 4 years) with this finding were studied. No subject had signs or symptoms of coronary artery disease. Subjects exercised on a bicycle ergometer to a double product of 26,000 +/- 2,000 (+/- standard error of mean). All but one of the subjects had at least 1 mm of ST-segment depression. Tests were terminated because of fatigue or dyspnea and no patient had chest pain. Thallium test results were abnormal in 5 patients, 2 of whom had stress defects as well as abnormally delayed thallium washout. One of these subjects had normal coronary arteries on angiography with a negative ergonovine challenge, and both had normal exercise radionuclide ventriculographic studies. Delayed thallium washout was noted in 3 of the subjects with ventricular preexcitation and normal stress images. This study suggests that exercise thallium testing is frequently abnormal in subjects with ventricular preexcitation. Ventricular preexcitation may cause dyssynergy of ventricular activation, which could alter myocardial thallium handling, much as occurs with left bundle branch block. Exercise radionuclide ventriculography may be a better test for noninvasive assessment of coronary artery disease in patients with ventricular preexcitation.

Adult↗
PubMed1987

The early diagnosis of peripheral vascular disease.

The time has long since passed when gangrene followed by amputation was the anticipated outcome of peripheral vascular disease of the extremities. Nevertheless, today in the United States it is estimated that there are more than half a million amputees. With preventive measures, early diagnosis, and adequate treatment, gangrene will be avoided and the patient will retain the use of his limbs.

Arterial Occlusive Diseases↗
PubMed1987

Radioimmunoscintigraphy and radioimmunotherapy of renal cell carcinoma xenografts.

From a panel of monoclonal antibodies (MAb) reactive with human renal cell carcinoma generated by this laboratory, three (designated A6H, C5H, and D5D) were selected for in vivo studies with a nude mouse xenograft model. These studies included 131I- and 111In-labeled MAb radioimmunoscintigraphy and 131I-labeled MAb radioimmunotherapy. In the imaging studies, these radiolabeled MAb allowed visualization of subcutaneous xenografts larger than 40 mg and subrenal capsule xenografts smaller than 20 mg. Comparisons of tumor to non-tumor tissue radiolabel distribution yielded unusually high ratios and depended on the MAb-xenograft combination. The 111In-radiolabeled A6H showed increased accumulation in the liver compared with 131I-A6H, but this still did not necessitate background subtraction for good visualization of small, subrenal capsule renal cell carcinoma xenografts. Radioimmunotherapy studies with 131I-A6H in BALB/c nu/nu mice bearing established renal cell carcinoma xenografts showed a prolonged (greater than 90 days) regression in tumor burden and possible "cures," whereas three sets of control mice showed progressive and rapid increases in tumor size. These studies indicated that MAb, which show good tissue biodistribution and high imaging sensitivity, could also be capable of delivering effective radiotherapy to the tumor when "human equivalent" radiolabeled-MAb doses are used.

Animals↗
PubMed1986

In-111 Pseudomonas aeruginosa: a simple method of labeling live bacteria with a gamma-emitting radioisotope.

We describe a simple and reliable technique for labeling Pseudomonas aeruginosa with a readily available commercial preparation of indium-111 (111In) oxine. Labeling of a heavy bacterial suspension with 500 mu Ci of commercially prepared 111In-oxine resulted in a yield of 0.0004 mu Ci of cell-associated 111In per 10(6) colony-forming units (CFU). The label was 88% bacterially associated and did not effect viability of the organism. Radiolabeling a gram-negative organism with 111In-oxine provides a non-toxic, stable gamma-emitting bacterial tracer.

Animals↗
PubMed1986

Antigen-induced experimental septic arthritis in rabbits after intraarticular injection of Staphylococcus aureus.

With the Dumonde-Glynn model of antigen-induced arthritis, a rabbit model was developed to examine the histopathologic differences between normal and arthritic joints in the same animal infected by intraarticular injections of Staphylococcus aureus. Microscopic examination of whole joint sections and a quantitative histopathologic scale were used to compare changes in all the articular components of 17 normal and 17 arthritic joints infected for less than two weeks. The histological changes were more severe in infected arthritic joints than in infected normal joints (mean +/- SD total histology score, 13.8 +/- 2.4 and 9.3 +/- 4.0, respectively; P less than .001). In infected arthritic joints, subsynovial abscesses extended into subchondral bone via the pannus of chronic synovitis at articular margins and intraarticular attachments of cruciate ligaments, rather than by initial cartilage destruction and direct extension into subchondral bone.

Abscess↗