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Biomedical subjects

J Kahn

Publications and source records attributed to J Kahn.

At least 37 records · Page 2Linked to original sources
PubMed2000

Compartment syndrome from balloon pump.

A 35-year-old man had significant left main coronary artery disease and required intra-aortic balloon catheter insertion owing to refractory ischemia before emergency coronary artery bypass graft. In the immediate postoperative period the patient started complaining of leg pain and diminished sensation in the right foot despite palpable pulses. The diagnosis of acute compartment syndrome of the right leg was made by an intracompartment pressure measurement of 90 mm Hg.

Adult↗
PubMed2000

Gene expression profiling in an in vitro model of angiogenesis.

In the present study we have used a novel, comprehensive mRNA profiling technique (GeneCalling) for determining differential gene expression profiles of human endothelial cells undergoing differentiation into tubelike structures. One hundred fifteen cDNA fragments were identified and shown to represent 90 distinct genes. Although some of the genes identified have previously been implicated in angiogenesis, potential roles for many new genes, including OX-40, white protein homolog, KIAA0188, a homolog of angiopoietin-2, ADAMTS-4 (aggrecanase-1), and stanniocalcin were revealed. Support for the biological significance was confirmed by the abrogation of the changes in the expression of angiogenesis inhibitors and in situ hybridization studies. This study has significantly extends the molecular fingerprint of the changes in gene expression that occur during endothelial differentiation and provides new insights into the potential role of a number of new molecules in angiogenesis.

Cells, Cultured↗
PubMed2000

A population pharmacokinetic analysis of the penetration of the prostate by levofloxacin.

Prostatitis has remained a pathological entity that is difficult to treat. Part of the difficulty revolves about the putative offending pathogens. For acute prostatitis, members of the Enterobacteriaceae, particularly Escherichia coli, play a central role, while intracellular pathogens such as Chlamydia are more frequently seen in chronic prostatitis. Consequently, a drug needs to be able to penetrate to this specialized site in both the acute and chronic infection forms of the disease and also have potent activity against the most common causative pathogens, both intracellular and extracellular. Levofloxacin has such an activity profile. We wished to document its ability to penetrate to the site of infection. Patients undergoing prostatectomies were administered 500 mg of levofloxacin orally every 24 h for 2 days prior to surgery, and then on the day of surgery, 500 mg was administered as an hour-long, constant-rate intravenous (i.v.) infusion. A set of blood samples was obtained as guided by stochastic optimal design theory. Prostate biopsy times were determined by randomizing subjects into one of four groups, based on the interval after the i.v. dose. All plasma and prostate drug concentrations were comodeled by a population modeling program, BigNPEM, implemented on the Cray T3E Supercomputer housed at the Supercomputer Center at the University of California at San Diego. Penetration was determined as the ratio of the area under the concentration-time curve (AUC) of levofloxacin in the prostate to the plasma levofloxacin AUC. When calculated from the mean population parameters, this penetration ratio was 2.96. We also performed a 1,000-subject Monte Carlo simulation from the mean parameter vector and covariance matrix. The mean penetration ratio here was 4.14 with a 95% confidence interval of 0.20 to 19.6. Over 70% of the population had a penetration ratio in excess of 1.0. Levofloxacin adequately penetrates a noninflamed prostate and should be evaluated for the therapy of prostatitis.

Aged↗
PubMed2000

Quantitative and cost comparison of ultrasensitive human immunodeficiency virus type 1 RNA viral load assays: Bayer bDNA quantiplex versions 3.0 and 2.0 and Roche PCR Amplicor monitor version 1.5.

Quantification of human immunodeficiency virus type 1 (HIV-1) RNA as a measure of viral load has greatly improved the monitoring of therapies for infected individuals. With the significant reductions in viral load now observed in individuals treated with highly active anti-retroviral therapy (HAART), viral load assays have been adapted to achieve greater sensitivity. Two commercially available ultrasensitive assays, the Bayer Quantiplex HIV-1 bDNA version 3.0 (bDNA 3.0) assay and the Roche Amplicor HIV-1 Monitor Ultrasensitive version 1.5 (Amplicor 1.5) assay, are now being used to monitor HIV-1-infected individuals. Both of these ultrasensitive assays have a reported lower limit of 50 HIV-1 RNA copies/ml and were developed from corresponding older generation assays with lower limits of 400 to 500 copies/ml. However, the comparability of viral load data generated by these ultrasensitive assays and the relative costs of labor, disposables, and biohazardous wastes were not determined in most cases. In this study, we used matched clinical plasma samples to compare the quantification of the newer bDNA 3.0 assay with that of the older bDNA 2.0 assay and to compare the quantification and costs of the bDNA 3.0 assay and the Amplicor 1.5 assay. We found that quantification by the bDNA 3.0 assay was approximately twofold higher than that by the bDNA 2.0 assay and was highly correlated to that by the Amplicor 1.5 assay. Moreover, cost analysis based on labor, disposables, and biohazardous wastes showed significant savings with the bDNA 3.0 assay as compared to the costs of the Amplicor 1.5 assay.

Acquired Immunodeficiency Syndrome↗
PubMed1999

Evaluation of ofloxacin in the treatment of laparoscopically documented acute pelvic inflammatory disease (salpingitis).

OBJECTIVE: To evaluate the safety and efficacy of intravenous and oral ofloxacin monotherapy in the treatment of laparoscopically documented acute pelvic inflammatory disease (PID). METHODS: This study was conducted as an open-label, phase-III, uncontrolled, multicenter study. Patients identified with laparoscopic findings of salpingitis were treated with 400 mg of intravenous ofloxacin every 12 hours followed by 400 mg of oral ofloxacin every 12 hours for 10 to 14 days. Patients were evaluated five times for clinical and microbial efficacy. Since laparoscopy was performed only at admission, pathogens identified laparoscopically were presumed eradicated if they were present on the laparoscopic culture and the patient was clinically cured or improved at final evaluation. RESULTS: Of the 70 patients evaluable for safety (intent-to-treat population), the mean age was 25.6 years. Sixty-one of 70 patients (87%) were cured, one improved, one did not improve, and seven were unevaluable because they discontinued study participation. Fifty-one were evaluable for clinical efficacy: 50 (98%) were cured and one did not improve. Sixteen were evaluable for expanded microbiological efficacy: three had documented Neisseria gonorrhoeae; 12, Chlamydia trachomatis; and one, a mixed infection of both organisms. All cervical, laparoscopic, and endometrial cultured pathogens, including N. gonorrhoeae and C. trachomatis, were eradicated or presumed eradicated at the posttherapy visit. No serious or unexpected adverse events occurred. CONCLUSIONS: Ofloxacin monotherapy was effective and well tolerated in the treatment of laparoscopically proven PID in a geographically diverse population. Future studies are necessary to evaluate long-term outcomes and sequelae of PID treatment with single agent therapy.

Administration, Oral↗
PubMed1999

Prevalence of dental occlusal variables and intraarticular temporomandibular disorders: molar relationship, lateral guidance, and nonworking side contacts.

STATEMENT OF PROBLEM: The association between dental occlusion and the development of intraarticular temporomandibular disorders remains unclear. PURPOSE: This study evaluated the prevalence of molar relationship, lateral guidance and nonworking side contacts and intraarticular temporomandibular disorders. MATERIAL AND METHODS: Eighty-two asymptomatic volunteers and 263 symptomatic temporomandibular disorder (TMD) patients completed a subjective questionnaire that documented the absence of jaw pain, joint noise, locking, and a positive history for TMD. Participants also underwent clinical and dental examination for signs and symptoms commonly associated with TMD or internal derangements. RESULTS: The most prevalent molar relationship was Class I. Symptomatic patients had a higher prevalence of Class II, Division 1 relationships on the left side compared with the asymptomatic volunteers with normal joints. There was a higher prevalence of canine guidance (52.04%; P <.005) on the right side in the symptomatic patients with disk displacement (DD). Volunteers with normal joints had a higher prevalence of 1 or more nonworking side contacts compared with symptomatic patients with normal joints (P <.001) and symptomatic patients with DD (P <. 001). CONCLUSION: This study suggests there are no systematic dental occlusal differences that clearly separate symptomatic from asymptomatic patients. Results indicate that it is unclear as to the relationship of the 3 analyzed factors and of intraarticular TMDs.

Chi-Square Distribution↗
PubMed1999

Booster immunization of HIV-1 negative volunteers with HGP-30 vaccine induces protection against HIV-1 virus challenge in SCID mice.

Eleven HIV-1 seronegative subjects previously injected with an HIV-1 p17 synthetic peptide vaccine (HGP-30) were given two booster immunizations to evaluate memory cell responses and the ability to boost cellular and humoral immune responses. Five of 11 subjects showed a significant increase in their antibody titres to HGP-30 or p17 and 6/11 had T-cell proliferation responses to either HGP-30 or p17. HIV-1 virus challenge studies in SCID mice demonstrated that 39 of 50 mice (78%) receiving PBMC from 5 of the HGP-30 immunized subjects were protected from infection with a different strain of HIV-1 compared to 4 of 30 mice (13%) that received PBMC from 3 non-immunized subjects (p < 0.001). These studies show that booster immunizations with HGP-30 vaccine are safe and non-toxic and induce protective cell mediated immune responses.

AIDS Vaccines↗
PubMed1999

High pregnancy rates and successful prevention of severe ovarian hyperstimulation syndrome by 'prolonged coasting' of very hyperstimulated patients: a multicentre study.

In a multicentre trial, 65 in-vitro fertilization (IVF)-embryo transfer cycles were severely hyperstimulated. Instead of cancelling the cycle, gonadotrophins were withheld for a 'coasting period' until serum oestradiol concentrations had dropped below 10,000 pmol/l (mean 4.3 days), and then human chorionic gonadotrophin was administered. Four cycles were cancelled and there were 61 oocyte aspirations. A total of 103 fresh embryos was transferred to 53 patients, resulting in a pregnancy rate of 42% per started cycle (51% per embryo transfer), with an implantation rate of 31%. Only one patient developed severe ovarian hyperstimulation syndrome (OHSS). Four patients developed moderate OHSS. In all, two patients were hospitalized for OHSS. In order to optimize the coasting procedure, it seems important that each IVF centre identifies its appropriate cut-off limits for serum oestradiol concentrations and follicle size for initiating and ending of the coasting period. Correctly handled, it seems to be a major advance in the search for improved stimulation policies for high-responders.

Adult↗
PubMed1999

Resistance surveillance of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis isolated in the United States, 1997-1998.

A national antimicrobial resistance surveillance study was conducted from December 1997 to May 1998 to determine the prevalence of antimicrobial resistance in 6620 clinical isolates of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis. In this centralized study, which involved 163 institutions located in 43 states, we determined MICs for representatives of five antimicrobial classes: beta-lactams (penicillin, co-amoxiclav, cefuroxime, ceftriaxone), macrolides (azithromycin, clarithromycin), co-trimoxazole, glycopeptides (vancomycin) and fluoroquinolones (levofloxacin). In most S. pneumoniae isolates, all antimicrobials were to be found active, but amongst penicillin-resistant isolates (MICs > or = 2 mg/L), resistance to other beta-lactams, macrolides and co-trimoxazole was common. For vancomycin and levofloxacin, however, activity was not associated with penicillin resistance. The prevalence of penicillin-nonsusceptible (intermediate and resistant) pneumococci was highest in the South Atlantic (44%) and East South Central (43%) regions and lowest in the Mid-Atlantic (28%) and New England (28%) regions. Resistance to beta-lactams, macrolides and co-trimoxazole was more commonly found amongst respiratory isolates than blood isolates and in strains from patients < or = 12 years old than from older patients. beta-lactamase, which was detected in 33% of H. influenzae and 92% of M. catarrhalis strains, did not affect the activity of the beta-lactams under study other than ampicillin. Certain agents, such as vancomycin and the fluoroquinolones, remain highly active, and well-designed surveillance systems that monitor MIC distributions would be needed to detect a potential for reduced susceptibility. In addition, surveillance programmes should be designed to collect information about associated resistance as well as differences in prevalence associated with region, specimen source and patient age.

Adolescent↗
PubMed1999

Hockey.

Hockey is a game of strength, speed, and skill. It is among the most difficult to master, the costliest to equip, the fastest to watch, and the most dangerous to play. It requires a combination of power, endurance, and flexibility applied within a confined space over a cold, hard, and slippery surface. It is a game of control and lack of control, both of emotions and flying objects. Hopefully, the reader will be better suited to understand the "culture" of hockey, both clinically and functionally, and can better interact with the men and women who play this fantastic sport, the one I hope to be playing for another 25 years, or until I finally get it right!

Adolescent↗
PubMed1998

Calmodulin regulates L-selectin adhesion molecule expression and function through a protease-dependent mechanism.

Expression of the L-selectin adhesion molecule is rapidly down-regulated upon cell activation through proteolysis at a membrane-proximal site. Here we demonstrate that calmodulin, an intracellular calcium regulatory protein, specifically coprecipitates with L-selectin through a direct association with the cytoplasmic domain of L-selectin. Furthermore, calmodulin inhibitors disrupt L-selectin-dependent adhesion by inducing proteolytic release of L-selectin from the cell surface. The effects of the calmodulin inhibitors on L-selectin expression and function can be prevented by cotreatment with a hydroxamic acid-based metalloprotease inhibitor. Our results suggest a novel role for calmodulin in regulating the expression and function of an integral membrane protein through a protease-dependent mechanism. These findings may have broader implications for other cell surface proteins that also undergo regulated proteolysis.

Amino Acid Sequence↗
PubMed1998

Clinical research designs for emerging treatments for Alzheimer disease: moving beyond placebo-controlled trials.

The design of clinical trials must evolve as new therapies become available. The demonstrated efficacy and clinical use of donepezil and vitamin E for Alzheimer disease (AD) has shifted the options for AD research design. There is now a compelling case for alternatives to trials that include a treatment arm with no active therapy (ie, a placebo control). With an existing therapy, such as donepezil or vitamin E, new drugs that are clearly superior to those drugs should be sought. Combination therapy is a likely strategy for the future, implying that clinical trials, if possible, should replicate actual practice. The long duration of future AD trials also will make placebo-controlled trials more difficult to justify and more difficult to recruit for. Add-on or active-control designs represent the alternative approaches. We believe that definitive clinical trials of new AD drugs that use one or the other of these designs would be more likely to bring about therapeutic advances than would comparisons with inactive treatments. Our argument is not a general rejection of placebo-control designs. Our recommendations apply only to the circumstances in which the field of AD drug therapy now finds itself.

Alzheimer Disease↗