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Biomedical subjects

S Kurtz

Publications and source records attributed to S Kurtz.

At least 37 records · Page 2Linked to original sources
PubMed1999

Adaptation of human enteric coronavirus to growth in cell lines.

BACKGROUND: The existence of human enteric coronavirus (HEC) has been debated since its first description in stool by electron microscopy (EM) in 1975. Needed to resolve the issue is its cultivation in readily available cell lines. OBJECTIVES: To grow HEC in cell lines. To describe its characteristics and to differentiate it from other human and animal coronaviruses. STUDY DESIGN: Originally grown in human fetal intestinal organ culture, HEC was passed in J774 cells (a mouse macrophage cell line) and C6/36 cells (a mosquito cell line). Its cytopathic effect (CPE) and pattern of immunofluorescence were described. Its appearance was ascertained by negative staining and transmission EM. Its structural proteins were delineated by polyacrylamide gel electrophoresis (PAGE) and Western blotting (WB). The antigenic character of the virus was determined by immunofluorescence and WB. Agglutination with mouse erythrocytes was performed. RESULTS: In J774 cells, HEC induced the formation of giant cells and small syncytia. Immunofluorescence in both J774 and C6/36 cells was limited to the cytoplasm. Studies with transmission EM revealed the virus to have the typical appearance of other coronaviruses, to be 80-120 nm in diameter, and to bud into cysternae of the endoplasmic reticulum. By PAGE and WB, its major protein has an average molecular weight (MW) of 41 kilodaltons (kDa). Two other proteins had MWs of 190 and 24 kDa. By immunofluorescence and WB, HEC is antigenically distinct from human coronaviruses 0C43 and 229E and mouse hepatitis virus (A59 strain). Preparations of HEC did not agglutinate mouse erythrocytes. CONCLUSION: We conclude that HEC is a human coronavirus that is antigenically unrelated to 0C43 and 229E viruses. Growth of HEC in readily available cell lines should aid in elucidating its role as a pathogen in human diarrheal illnesses.

Adaptation, Biological↗
PubMed1999

Role of aspirin in reducing the frequency of second eye involvement in patients with non-arteritic anterior ischaemic optic neuropathy.

PURPOSE: To retrospectively evaluate in patients with non-arteritic ischaemic optic neuropathy (NAION) whether aspirin reduces the frequency of second eye involvement. METHODS: In 52 patients who presented with NAION between 1984 and 1997 adequate information was available regarding use of aspirin, presence of risk factors and second eye involvement. RESULTS: Second eye involvement was noted in 8 of 16 patients (50%) who did not receive aspirin, in 3 of 8 patients (38%) who received 100 mg/day aspirin and in only 5 of 28 patients (18%) who received aspirin 325 mg/day. Moreover, mean time to second eye involvement was 63 months in patients who did not receive aspirin versus 156 months in patients who received aspirin 325 mg/day. CONCLUSION: Our results strongly suggest that aspirin at 325 mg/day may be effective in reducing the frequency of second eye involvement with NAION.

Adult↗
PubMed1999

Humor as a perioperative nursing management tool.

Humor is a powerful tool for accomplishing management goals. This article offers suggestions for using humor to relieve stress, cultivate teamwork, buy attention, improve morale, increase productivity, foster communication, enhance problem solving, and create a positive work culture in the operating room.

Burnout, Professional↗
PubMed1997

Tubeless percutaneous renal surgery.

PURPOSE: We challenge the requirement for routine placement of a nephrostomy tube following percutaneous renal surgery. MATERIALS AND METHODS: A total of 50 patients underwent tubeless percutaneous renal procedures consisting of nephrolithotripsy, endopyelotomy, and stone extraction plus endopyelotomy performed during the same setting. In the initial 30 patients a Double-J* stent and a Councill nephrostomy tube were placed at the end of the procedure. The Councill catheter was removed 2 to 3 hours postoperatively. The subsequent 20 patients received only a Double-J stent with no Councill catheter. This study group was compared to a control group of 50 age, sex and procedure matched patients who had previously undergone standard percutaneous renal procedures with routine placement of postoperative nephrostomy tubes. The incidence of complications, analgesia requirements, length of hospitalization, interval to return to normal activities and cost of treatment were compared between the 2 groups. RESULTS: All 50 tubeless percutaneous procedures were performed successfully without significant complications. In the initial 15 patients postoperative renal ultrasound demonstrated no urinoma. Hospitalization was 0.6 days for the study group and 4.6 days for the controls (p = 0.0001). Average parenteral or intramuscular analgesia requirements were 11.58 and 36.06 mg. morphine sulfate, respectively (p = 0.0001), with patients requiring oral analgesia for 5.9 and 11.7 days, respectively (p = 0.0001). Patients in the study group returned to normal activities within 17.85 days versus 26.6 days for the controls (p = 0.0004). The costs of the procedures were $1,638 and $3,750 (129% greater), respectively, for a cost saving of $2,112 per case. CONCLUSIONS: Tubeless percutaneous renal surgery is a safe procedure and offers numerous advantages over routine placement of a nephrostomy tube. The hospitalization, analgesia requirements, return to normal activities as well as cost are significantly less with this new technique.

Female↗
PubMed1996

Use of microphysiometry for analysis of heterologous ion channels expressed in yeast.

Measurement of extracellular acidification rates by microphysiometry provides a means to analyze the function of ion channels expressed in yeast cells. These measurements depend on the proton pumping action of the H(+)-ATPase, a central component of the yeast plasma membrane. We used microphysiometry to analyze the activity of two ion channels expressed in yeast. In one example, an inwardly rectifying K+ channel, gpIRK1, provides a potassium uptake function when expressed in a potassium transporter-defective yeast strain. Rates of acidification in gpIRK1-expressing cells directly reflect channel function. Addition of cesium, an inhibitor of gpIRK1 activity, results in an immediate reduction in acidification rates. In a second example, expression of a nonselective cation channel, the influenza virus M2 protein, is believed to interfere with the maintenance of the electrochemical proton gradient by the H(+)-ATPase. In cells expressing the M2 channel, addition of inhibitors increases the rate of proton extrusion. Moreover, functional differences between two M2 inhibitors, amantadine and BL-1743, are distinguished by the microphysiometer. This application demonstrates the utility of the microphysiometer for functional studies of ion channels; it is adaptable to a screening process for compounds that modulate ion channel activity.

Biosensing Techniques↗
PubMed1996

Characterization of inhibition of M2 ion channel activity by BL-1743, an inhibitor of influenza A virus.

The influenza A virus M2 integral membrane protein has ion channel activity that can be inhibited by the antiviral drug amantadine. Recently, a spirene-containing compound, BL-1743 (2-[3-azaspiro (5,5)undecanol]-2-imidazoline), that inhibits influenza virus growth was identified (S. Kurtz, G. Lao, K. M. Hahnenberger, C. Brooks, O. Gecha, K. Ingalls, K.-I. Numata, and M. Krystal, Antimicrob. Agents Chemother. 39:2204-2209, 1995). We have examined the ability of BL-1743 to inhibit the M2 ion channel when expressed in oocytes of Xenopus laevis. BL-1743 inhibition is complete as far as can be measured by electrophysiological methods and is reversible, with a reverse reaction rate constant of 4.0 x 10(-3) s(-1). In contrast, amantadine inhibition is irreversible within the time frame of the experiment. However, BL-1743 inhibition and amantadine inhibition have similar properties. The majority of isolated influenza viruses resistant to BL-1743 are also amantadine resistant. In addition, all known amino acid changes which result in amantadine resistance also confer BL-1743 resistance. However, one BL-1743-resistant virus isolated, designated M2-I35T, contained the change Ile-35-->Thr. This virus is >70-fold more resistant to BL-1743 and only 10-fold more resistant to amantadine than the wild-type virus. When the ion channel activity of M2-I35T was examined in oocytes, it was found that M2-I35T is BL-1743 resistant but is reversibly inhibited by amantadine. These findings suggest that these two drugs interact differently with the M2 protein transmembrane pore region.

Amantadine↗
PubMed1995

Functional expression of a vertebrate inwardly rectifying K+ channel in yeast.

We describe the expression of gpIRK1, an inwardly rectifying K+ channel obtained from guinea pig cardiac cDNA. gpIRK1 is a homologue of the mouse IRK1 channel identified in macrophage cells. Expression of gpIRK1 in Xenopus oocytes produces inwardly rectifying K+ current, similar to the cardiac inward rectifier current IK1. This current is blocked by external Ba2+ and Cs+. Plasmids containing the gpIRK1 coding region under the transcriptional control of constitutive (PGK) or inducible (GAL) promoters were constructed for expression in Saccharomyces cerevisiae. Several observations suggest that gpIRK1 forms functional ion channels when expressed in yeast. gpIRK1 complements a trk1 delta trk2 delta strain, which is defective in potassium uptake. Expression of gpIRK1 in this mutant restores growth on low potassium media. Growth dependent on gpIRK1 is inhibited by external Cs+. The strain expressing gpIRK1 provides a versatile genetic system for studying the assembly and composition of inwardly rectifying K+ channels.

Amino Acid Sequence↗
PubMed1995

Growth impairment resulting from expression of influenza virus M2 protein in Saccharomyces cerevisiae: identification of a novel inhibitor of influenza virus.

The gene encoding M2, the ion channel-forming protein of influenza virus A, was expressed under the control of an inducible promoter in Saccharomyces cerevisiae. By using single and multicopy plasmids containing GAL promoter-M2 fusions, a correlation was observed between plasmid copy number and growth in medium inducing M2 expression. Cells expressing M2 from multicopy plasmids have reduced growth rates, suggesting that high levels of M2 are toxic to growth. The addition of amantadine, a compound known to block the ion channel activity of certain M2 alleles, restores the growth rates to wild-type levels in cells expressing an amantadine-susceptible allele of M2 but not an amantadine-resistant allele of M2, suggesting that M2 expression in S. cerevisiae results in the formation of functional M2 ion channels. Measurements of extracellular acidification by microphysiometry suggest that proton efflux in M2-expressing cells is altered and that the addition of amantadine permits the reestablishment of the proton gradient. The growth impairment phenotype resulting from M2 expression was used to develop a high-capacity screening assay which identified a novel inhibitor possessing an antiviral profile similar to that of amantadine.

Amantadine↗
PubMed1994

[Cataract surgery in Israel, 1984-1991].

A review of cataract surgery and intraocular lens implantation in Israel between 1984-1991 is presented. During these 7 years the number of cataract operations increased by 50%, with a significant increase in operations in private hospitals. The proportion of intraocular lens implantations increased from 47% to 93%, predominantly posterior chamber implantations. A rapid transition from intracapsular to extracapsular extraction was documented.

Cataract Extraction↗
PubMed1994

Analysis of reproductive health hazard information on material safety data sheets for lead and the ethylene glycol ethers.

Material Safety Data Sheets (MSDSs) are essential sources of information regarding health risks from exposure to toxic chemicals. We analyzed the reproductive health hazard descriptions on nearly 700 MSDSs for lead- or ethylene glycol ether-containing products submitted by central Massachusetts firms to the Department of Environmental Protection under provisions of the Massachusetts Right-to-Know Law. Over 60% of the MSDSs made no mention whatsoever of effects on the reproductive system. Those that did were much more likely to address developmental risks than male reproductive effects. The MSDSs from firms employing 100 or more workers mentioned reproductive system effects more frequently than those from smaller companies. While the informativeness of the health hazard descriptions increased over time, 53% of the MSDSs prepared after promulgation of the OSHA Hazard Communication Standard still contained no information on reproductive risks.

Chemical Industry↗
PubMed1994

Hydroexpression of subluxated lenses using a glide.

During the past 8 years, 15 patients (20 eyes) underwent a variety of operations to remove a subluxated lens. In six of these eyes, a new technique, featuring an anterior chamber maintainer and a plastic glide, was used for intracapsular cataract extraction (ICCE). The results achieved in these eyes were compared with those in 8 eyes in which cryo extraction was used, in 1 in which pars plana lensectomy was used, in 4 in which aspiration of lens material and peeling of the capsule was used, and in 1 in which a viscoelastic material and spatula were used. Using the glide, the lens is extracted through a scleral tunnel incision or a limbal opening. The length of the opening is somewhat smaller than the diameter of the lens and is significantly smaller than that used in traditional ICCE. The visual outcomes achieved with these various techniques were essentially identical. The proposed technique is simple and relatively safe for these complicated cases.

Adult↗
PubMed1993

An essential yeast gene encoding a TTAGGG repeat-binding protein.

A yeast gene encoding a DNA-binding protein that recognizes the telomeric repeat sequence TTAGGG found in multicellular eukaryotes was identified by screening a lambda gt11 expression library with a radiolabeled TTAGGG multimer. This gene, which we refer to as TBF1 (TTAGGG repeat-binding factor 1), encodes a polypeptide with a predicted molecular mass of 63 kDa. The TBF1 protein, produced in vitro by transcription and translation of the cloned gene, binds to (TTAGGG)n probes and to a yeast telomeric junction sequence that contains two copies of the sequence TTAGGG separated by 5 bp. TBF1 appears to be identical to a previously described yeast TTAGGG-repeat binding activity called TBF alpha. TBF1 produced in vitro yields protein-DNA complexes with (TTAGGG)n probes that have mobilities on native polyacrylamide gels identical to those produced by partially purified TBF alpha from yeast cells. Furthermore, when extracts are prepared from a strain containing a TBF1 gene with an antigen tag, we find that the antigen copurifies with the predominant (TTAGGG)n-binding activity in the extracts. The DNA sequence of TBF1 was determined. The predicted protein sequence suggests that TBF1 may contain a nucleotide-binding domain, but no significant similarities to any other known proteins were identified, nor was an obvious DNA-binding motif apparent. Diploid cells heterozygous for a tbf1::URA3 insertion mutation are viable but upon sporulation give rise to tetrads with only two viable spores, both of which are Ura-, indicating that the TBF1 gene is essential for growth. Possible functions of TBF1 (TFB alpha) are discussed in light of these new results.

Amino Acid Sequence↗
PubMed1993

Occupational and environmental reproductive hazards education and resources for communities of color.

Little research has been published on the occupational and environmental hazards affecting people of color. Even less is known about the hazards that affect women of color. Although women of color have always been aggressive participants in the work force, their labor activity has increased dramatically over the last decade. Current job placement patterns suggest that women of color are concentrated in the lowest-paying and most hazardous jobs. In this paper, we specifically focus on occupational and environmental reproductive health concerns. We write with the understanding that reproductive hazards can affect pregnant women, nonpregnant women, and men, as well as the health and development of young children. Emphasis is placed primarily on African American women, because information on Hispanic, Native American, and Asian women is very limited. We discuss the participation of women of color in the labor force, using the U.S. Department of Labor categories. We review specific occupational hazards associated with each category of work and briefly discuss environmental hazards, noting that communities of color are at a disproportionate risk of exposure. Finally, we present the consensus report of the Community Education Working Group from the Woods Hole Conference on Occupational and Environmental Reproductive Hazards.

Black or African American↗
PubMed1993

Orbital pseudotumor presenting as acute glaucoma with choroidal and retinal detachment.

A 68-year-old woman presented with acute visual loss, elevated intraocular pressure (IOP), and a flat anterior chamber combined with retinal and choroidal detachment. The diagnosis of orbital pseudotumor was based on the patient's poor response to conventional therapy and on computerized tomography and ultrasound findings. After treatment with oral corticosteroids, the inflammatory process, elevated IOP, and choroidal and retinal detachment resolved.

Acute Disease↗
PubMed1992

Leukocyte reduction in blood component therapy.

PURPOSE: To review methods of preventing or minimizing the adverse effects associated with the transfusion of passenger leukocytes present in cellular blood components and to define groups of patients who are at risk for adverse effects. DATA SOURCES: English-language articles on transfusion medicine. STUDY SELECTION: Original reports describing the pathogenesis of leukocyte-induced adverse effects in transfusion recipients and the influence of leukocyte-reduced blood components on these effects. DATA EXTRACTION: Evaluation of the diagnosis, transfusion history, and treatment of the study patients; the methods and results of leukocyte reduction; and specific outcomes, including development of alloimmunization to leukocytes, febrile reactions to transfusion, and platelet refractoriness. DATA SYNTHESIS: Passenger leukocytes are the chief cause of alloimmunization to human leukocyte antigen (HLA) and leukocyte-specific antigens in transfusion recipients. Alloimmunization may result in febrile transfusion reactions, platelet refractoriness, and acute lung injury. Leukocytes are also the vector for transfusion-associated cytomegalovirus infection. Technologic advances in the leukocyte reduction of cellular blood components have made it possible to reduce the number of leukocytes to fewer than 10(7) per transfusion. Findings suggest that the use of leukocyte-reduced cellular blood components may minimize or prevent recurrent febrile reactions and alloimmunization to leukocyte antigens. Cytomegalovirus may not be transmitted by blood components containing fewer than 10(7) leukocytes. CONCLUSIONS: Leukocyte reduction in red blood cell and platelet transfusions using third-generation filters is indicated for selected patients who are likely to receive long-term transfusion support, to prevent recurrent febrile reactions and to prevent or delay alloimmunization to leukocyte antigens. Leukocyte-depleted transfusions may also be indicated to delay or prevent refractoriness to platelet transfusion.

Blood Component Transfusion↗
PubMed1991

RAP1 protein activates and silences transcription of mating-type genes in yeast.

RAP1 is a sequence-specific DNA-binding protein essential for cell growth. The occurrence of RAP1-binding sites in many promoter regions, the mating-type gene silencer elements, and telomeres suggests that RAP1 has multiple functions in the cell. To assess its role in transcription, temperature-sensitive mutations in RAP1 were generated. Analysis of rap1ts strains provides evidence that RAP1 functions in both transcriptional activation and silencing of mating-type genes. Several observations indicate that rap1ts strains are defective in the expression of MAT alpha, whose upstream activation sequence (UAS) contains a RAP1-binding site. At nonpermissive temperatures, decreases in MAT alpha steady-state transcript levels can be detected in MAT alpha rap1ts strains. Furthermore, these strains are deficient in alpha-pheromone production and simultaneously express at least two alpha-specific genes. These phenotypes can be reversed by replacing the RAP1-binding site at MAT alpha with a binding site for the GAL4 transcriptional activator. Certain rap1ts alleles have an opposite effect on the silent mating-type locus HMR, which becomes partially derepressed at nonpermissive temperatures.

Alleles↗