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Biomedical subjects

S H Cohen

Publications and source records attributed to S H Cohen.

At least 19 recordsLinked to original sources
PubMed1995

The relationship between antecedent antibiotic use and resistance to extended-spectrum cephalosporins in group I beta-lactamase-producing organisms.

Gram-negative pathogens are increasingly resistant to extended-spectrum cephalosporins (ESCs). Using a prospective, case-controlled observational study, we examined the prevalence and the risk factors for development of resistance to ESCs in group I beta-lactamase-producing organisms. Of the 386 isolates of Enterobacter species, Pseudomonas aeruginosa, Citrobacter species, and Serratia marsescens from 340 consecutive patients, 70 (18.1%) were resistant to ESCs; the highest rates of resistance were found among Citrobacter freundii (40.9%), Enterobacter cloacae (31.1%), and Enterobacter aerogenes isolates (18.9%). Patients' prior antibiotic use and the mean number of antibiotics used were significantly greater in association with resistant vs. susceptible isolates. Resistance was associated with prior use of ceftizoxime or cefotaxime (P = .008), ceftazidime (P = .004), and piperacillin (P = .001). Other antibiotics were not associated with resistance. Resistance was less frequent in patients receiving ESCs and an aminoglycoside. We conclude that prior use of ESCs is associated with the isolation of resistant group I beta-lactamase-producing organisms. Concomitant use of an aminoglycoside may decrease this risk.

Adult↗
PubMed1995

Genomic fingerprinting of epidemic and endemic strains of Stenotrophomonas maltophilia (formerly Xanthomonas maltophilia) by arbitrarily primed PCR.

Arbitrarily primed PCR (AP-PCR) was used to type 64 clinical isolates of Stenotrophomonas maltophilia from 60 patients and the hands of one nurse. Forty-seven different patterns were observed, most patients having isolates with unique genomic fingerprints. A single pattern, however, was obtained from six of eight patients involved in an intensive care nursery outbreak, confirming the suspected nosocomial transmission of this microorganism. This strain was also found in four other patients hospitalized at the same time but in different units. AP-PCR typing results had a good correlation with the 49 patterns obtained when the isolates were typed by contour-clamped homogeneous electric field gel electrophoresis. Although AP-PCR is slightly less discriminatory than contour-clamped homogeneous electric field gel electrophoresis, it offers several advantages and should be considered as a practical option for molecular typing during investigations of outbreaks.

Bacterial Typing Techniques↗
PubMed1994

Evaluation of nedocromil sodium 2% ophthalmic solution for the treatment of seasonal allergic conjunctivitis.

During peak ragweed season, 86 patients with seasonal allergic conjunctivitis participated in a 9-week, multicenter, double-masked, placebo-controlled, group-comparative study testing the efficacy and safety of bid nedocromil sodium, 2% ophthalmic solution. The clinical effectiveness of nedocromil sodium was measured by analyzing the means of patient daily symptom scores and eye examinations after 1, 3, 5, and 8 weeks of treatment. The use of nedocromil sodium during peak ragweed pollen season reduced symptom scores with statistically significant treatment differences as compared with the placebo for itchy eyes, tearing, overall eye condition, and symptom summary score. Clinician assessments also favored the use of nedocromil sodium as indicated by significant improvements in tearing, conjunctival injection, and conjunctival edema. No significant side effects were reported by the patients, allergists, or ophthalmologists. We conclude that nedocromil sodium, 2% ophthalmic solution, administered bid is more effective in the relief of symptoms of seasonal allergic conjunctivitis than placebo and causes no major side effects.

Adolescent↗
PubMed1992

Intracellular amplification of proviral DNA in tissue sections using the polymerase chain reaction.

We developed a new method to amplify cell DNA in situ using the polymerase chain reaction (PCR). Proviral sequences of mouse mammary tumor virus (MMTV) contained in cultured cells and tissue sections were amplified intracellularly using a thermal cycler. Two techniques were employed to maintain the localization of the amplified DNA. First, complementary tails at the 5' ends of the oligonucleotide primers resulted in the synthesis of high molecular weight concatamers containing the target sequences. Second, the PCR was carried out in a thin film of agarose solidified over the tissue sections. The specifically amplified and localized DNA was then detected by in situ hybridization (ISH). Our results demonstrate that (a) DNA in tissue sections can serve as the target for the polymerase chain reaction in situ, (b) cell morphology is maintained, and (c) a target of 167 BP can be specifically detected in individual cells. This technique should be generally applicable to amplifying cellular DNA targets in tissue sections for detection in situ.

Animals↗
PubMed1992

Decreases in unintegrated HIV DNA are associated with antiretroviral therapy in AIDS patients.

Better markers are needed to monitor the efficacy of antiretroviral drugs in persons infected with human immunodeficiency virus (HIV). We investigated the effects of zidovudine (ZDV) and dideoxycytidine (ddC) on the presence of unintegrated HIV-1 DNA in peripheral blood mononuclear cells (PBMCs) from AIDS patients. DNA was extracted from PBMCs and separated into low molecular weight (unintegrated) and high molecular weight (integrated) chromosomal fractions. These DNA fractions were then amplified by a quantitative polymerase chain reaction (PCR) and the amount and percentage of unintegrated HIV DNA were determined. Very high levels of unintegrated HIV DNA were found in AIDS patients not receiving treatment with ZDV or ddC (median = 95% unintegrated HIV DNA). In contrast, most patients who had received 4 or more weeks of antiretroviral therapy had lower levels of unintegrated HIV DNA (median = 30% unintegrated HIV DNA for patients receiving ZDV). Paired samples taken from five patients before and after therapy showed a striking reduction in the percentage of unintegrated HIV DNA. The decrease in the proportion of unintegrated HIV DNA in AIDS patients was due to both a reduction in the copy number of unintegrated HIV DNA and an increase in the copy number of integrated HIV DNA. Thus, measurements of unintegrated and integrated HIV DNA may be useful in providing objective assessments of the effectiveness of antiretroviral therapies.

Acquired Immunodeficiency Syndrome↗
PubMed1991

A seven-year experience with methicillin-resistant Staphylococcus aureus.

From July 1983 through June 1990, 319 patients with methicillin-resistant Staphylococcus aureus (MRSA) were identified at the University of California, Davis Medical Center. Initially, our goal was eradication of MRSA from the hospital flora. Our approach was: (a) immediate notification of all MRSA isolates by the microbiology laboratory; (b) strict isolation; (c) cohorting; (d) bathing patients with an iodophor; (e) surveillance cultures of patients and staff; (f) treatment of all colonized persons; and (g) strict isolation on readmission. Control of spread was achieved but eradication was not. In 1987 our strategy was modified in order to establish the least restrictive methods to maintain control of the spread of MRSA. After notification by the microbiology laboratory, we now require: (a) contact isolation; (b) surveillance cultures of patients associated with each new case; and (c) contact isolation for all MRSA patients on readmission. Strict isolation and employee culturing are used only during major outbreaks. We have averaged four new cases of MRSA per month over the 7-year period, including four major outbreaks. Since 1987, we have averaged only three new cases per month with one major MRSA outbreak. Annual cost savings of greater than $50,000 have been realized through the policy modifications. We conclude that the use of contact isolation with some modifications has saved time and money and has successfully controlled the spread of MRSA in our university hospital.

Adult↗
PubMed1990

Construction and characterization of two infectious molecular clones of encephalomyocarditis virus.

We constructed and characterized two infectious molecular clones of encephalomyocarditis (EMC) virus. Both constructs, pDL and pDA, were assembled from five overlapping cDNA clones derived from the diabetogenic variant of EMC virus (EMC-D) and from two synthetic oligonucleotide cartridges. pDA contained a single point mutation at position 1720 within the "puff" region of capsid protein 1AB that was derived from the nondiabetogenic variant of EMC virus (EMC-B). This point mutation resulted in an amino acid substitution of arginine (EMC-B) for lysine (EMC-D). Our construction illustrates two novel findings: (i) that the problem of stably cloning long poly(C) tracts of EMC virus can be circumvented by the use of a shortened, synthetic, poly(dC-dG) oligonucleotide cartridge, and (ii) that a single point mutation in the puff region of the capsid protein 1AB leads to change in its electrophoretic mobility and to a change in the plaque size of recombinant virus.

Animals↗
PubMed1988

Comparison of the nucleotide sequences of diabetogenic and nondiabetogenic encephalomyocarditis virus.

The nucleotide sequences of a diabetogenic variant of encephalomyocarditis (EMC) virus (D variant, ifp- phenotype) and a nondiabetogenic variant of EMC virus (B variant, ifp+ phenotype) have been compared. These variants differ at eight sites. The poly(C) tract of EMC-B is three bases shorter than that of EMC-D. Of the seven sites at which nucleotide substitutions were confirmed using RNA templates, four resulted in amino acid changes in three different proteins, the leader peptide, 1B (VP2), and 1D (VP1). The biological significance of these differences can now be investigated.

Amino Acid Sequence↗
PubMed1988

Multilumen catheter sepsis and an educational program to combat it.

Catheter-related sepsis is a problem with many variables. A process of elimination may eventually identify the actual cause(s) of this phenomenon. We began our problem-solving approach by observing personnel inserting and caring for central lines, which showed a lack of compliance with existing protocols. A program was designed to provide the correct procedural activities. This study plans to test whether ongoing educational programs and an infection control department that maintains a high degree of visibility are effective in reducing nosocomial line-related infections.

Catheterization, Central Venous↗
PubMed1988

In situ detection of human immunodeficiency virus (HIV) nucleic acid in H9 cells using nonradioactive DNA probes and an image cytophotometry system.

Rapid and sensitive nonradioactive methods to detect human immunodeficiency virus (HIV)-infected cells are needed in clinical medicine. We developed an in situ hybridization test using 2-acetylaminofluorene (AAF)-labeled HIV DNA as a hybridization probe. Hybridized probe was detected using rabbit anti-AAF antibody, followed by alkaline phosphatase-conjugated goat anti-rabbit, and the bromochloroindolyl phosphate-nitroblue tetrazolium reaction. An image cytophotometry system was used to quantitate the percentage of HIV-infected cells. These methods were used to determine the percentage of H9 cells infected with HIV. HIV was detected in 0% of cells on day 1 post infection, 7% on day 4, 41% on day 8, and 5% on day 15. These results paralleled those of the reverse transcriptase assay and an antigen capture ELISA assay for HIV antigen. Thus the AAF modified HIV DNA probe detected HIV nucleic acid in infected H9 cells and the image cytophotometry system improved the sensitivity and objectivity of detection.

2-Acetylaminofluorene↗
PubMed1988

Experimental evaluation of public policy: the case of state legislation for child passenger safety.

Observations of children in automobiles were made in seven states before and after implementation of legislation requiring use of child passenger safety devices. Increases in safe seating for children covered by state laws and children under 1 year old were observed in three of the five states implementing legislation during this study. Decreases in safe seating for these age groups were observed in two states, however. Increases in safe seating for children from 1 to 5 years old were observed in four of these five states. Although methodological limitations require cautious interpretation, these data suggest the impact child safety seat laws may have on compliance. Implications of this research for policies on child passenger safety and the importance of exploiting naturally occurring public experiments are discussed.

Accident Prevention↗
PubMed1987

The genomic RNA of diabetogenic encephalomyocarditis virus: characterization and molecular cloning.

The RNA of a diabetogenic variant of encephalomyocarditis (EMC) virus (D variant, ifp- phenotype) and a nondiabetogenic variant of EMC virus (B variant, ifp+ phenotype) which were derived from the same virus stock (M strain) have been compared. The size of both genomes is estimated at 7.7 kb. The poly(C) tract of EMC-D is estimated at 144 bases, whereas that of EMC-B is 141 bases in length. The untranslated 5' terminal 103 nucleotides are identical for B and D with preservation of a stable terminal hairpin structure. The entire open reading frame of both variants has been cloned and the restriction maps of 12 different enzymes are identical. These maps were compared to a computer-generated restriction map of another strain of EMC virus which has been cloned and sequenced by Palmenberg et al. (1984, Nucleic Acids Res. 12, 2969-2985). Approximately 50% of the restriction sites of the B and D variants had similar locations in this strain of EMC. We conclude that significant genetic variation exists between the M strain (B and D variants) and the Palmenberg strain of EMC virus. However, the B and D variants are very similar at the molecular level and comparison of their nucleotide sequences will be necessary to reveal the basis for their different biological properties.

Animals↗
PubMed1987

Ovine pulmonary transit of tetracycline and minocycline.

Following cannulation of the right external jugular vein and the efferent duct of the right caudal mediastinal lymph node (the caudal end of this node was ligated to cut off the inflow of systemic lymph, i.e., 90%-95% of the efferent lymph was of pulmonary origin), sheep were given either tetracycline or minocycline as single doses of 5 mg/kg body weight infused intravenously over 30 min. Venous blood plasma and pulmonary lymph collected contemporaneously before infusion and from 5 min to 24 hr postinfusion were assayed by a well-agar diffusion method using Bacillus cereus. Peak concentrations of both drugs were observed in both plasma and lymph at 5 min postinfusion. Tetracycline penetrated into the lymph better than minocycline (percent penetration 67.3% of cf. 38.2%). The concentration of tetracycline was significantly higher in lymph during and 5 min postinfusion (p less than 0.01), a factor that may be of importance when selecting a tetracycline for the treatment of a pulmonary infection.

Animals↗
PubMed1987

Comparison of non-radioactive DNA hybridization probes to detect human immunodeficiency virus nucleic acid.

Simple and sensitive methods to directly detect the human immunodeficiency virus (HIV) are needed for routine use in the clinical laboratory. In this study, we compared DNA probes prepared by: (1) nick translation with biotinylated dATP; (2) direct covalent biotinylation with photobiotin; (3) direct covalent reaction with 2-acetylaminofluorene (AAF); and (4) a standard radioactive (32P) nick translation procedure. These four DNA probes were hybridized with dilutions of purified target HIV DNA blotted onto nitrocellulose strips. Hybridization was detected using a complex of strepavidin-alkaline phosphatase [for (1) and (2)], alkaline phosphatase-tagged antibodies [for (3)] and by autoradiography [for (4)]. Alkaline phosphatase was detected colorimetrically using nitroblue tetrazolium and 5-bromo-4-chloro-3-indolyl phosphate. After 1 h, AAF probes were most sensitive (amount detected less than 5 pg), followed by biotin (10 pg), photobiotinylated probes (20 pg) and the radioactive probe (10 pg). The AAF probes were then used to detect HIV DNA in infected CEM cells. We conclude that non-radioactive DNA labelling methods can be used to directly detect HIV DNA under conditions compatible with present clinical laboratory procedures.

2-Acetylaminofluorene↗
PubMed1986

Consumer preference for personal drug information source: relationship to perceived importance of drug class.

The purposes of this study were to: (1) determine consumer preferences for personal drug information sources, and (2) determine if preference for information source is affected by perceived drug importance. A telephone survey of 204 metropolitan subjects was conducted using a systematic sampling design. Pharmacists and physicians were preferred over lay sources for all drug categories. Pharmacists and physicians were preferred equally for drugs perceived of low to moderate importance, but not for drugs perceived of highest importance. Perceived drug importance, which has not been examined previously, appears to be an important factor in consumers' preference for personal drug information sources.

Community Participation↗
PubMed1984

Entry of four cephalosporins into the ovine lung.

Following cannulation of the right external jugular vein and the efferent duct of the right caudal mediastinal lymph node (the caudal end of this node having been ligated to cut off the inflow of systemic lymph), sheep were each given one of four "cephalosporins" (cefazolin, moxalactam, cefoperazone, or ceftriaxone) as single doses injected iv over 30 min. All of the drugs appeared in the pulmonary lymph during iv infusion. Peak concentrations in the lymph were attained at 5 min postinfusion with cefazolin, cefoperazone, and ceftriaxone; the peak for moxalactam was attained at 30 min postinfusion. Cefazolin and cefoperazone penetrated better than did ceftriaxone, which penetrated better than did moxalactam. The concentrations of moxalactam, as compared with the other drugs, declined more gradually in both venous blood and pulmonary lymph. In view of the prompt entry and transit through the lungs and the high concentrations attained in the pulmonary lymph, these drugs should be effective in the treatment of pneumonias caused by susceptible bacteria.

Albumins↗