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Biomedical subjects

L S Fisher

Publications and source records attributed to L S Fisher.

8 recordsLinked to original sources
PubMed2006

Instability of a two-layer thin liquid film with surfactants: Dewetting waves.

Dewetting dynamics of a liquid film composed of two superposed ultra-thin layers of immiscible liquids resting on a solid substrate is investigated in the case when surfactants are present at the liquid-liquid interface. Two cases are considered: insoluble surfactant and surfactant soluble in the lower liquid. The dependence of Hamaker constants on the surfactant concentration is taken into account. A system of three strongly nonlinear evolution equations describing large (comparable to the layer thicknesses), long-wave perturbations of the liquid-liquid and liquid-gas interfaces, as well as the surfactant concentration, is derived for each case in the lubrication approximation. The linear stability analysis shows that in the presence of surfactants, oscillatory dewetting instability can occur. Numerical simulations of this system of nonlinear evolution equations are performed. It is found that in the case of oscillatory instabilities, the system exhibits either standing or traveling "dewetting waves." The weakly nonlinear analysis explains this phenomenon.

Journal Article↗
PubMed2005

Nonlinear stability analysis of a two-layer thin liquid film: dewetting and autophobic behavior.

The nonlinear stability analysis of a liquid film composed of two superposed thin layers of immiscible liquids resting on a solid substrate is performed. It is shown that the coupling of van der Waals interactions in the two layers can lead to an autophobic behavior in the form of spinodal decomposition of two planar liquid layers into a system of localized drops divided by almost planar wetting layers. The results of the weakly nonlinear analysis near the instability threshold are confirmed by the numerical solution of a system of two strongly nonlinear evolution equations for the liquid-liquid and liquid-gas interfaces. The kinetics of the drop coarsening at late stages is studied and is found to be close to that reported for a one-layer film. It is also shown that gravity effects can become significant even for very thin two-layer films.

Journal Article↗
PubMed1977

Anorectal gonococcal infection.

Anorectal gonococcal infection is common in women and homosexual men. In women with uncomplicated gonorrhea, the mean prevalence rate of anorectal involvement is 44%, with lone involvement of the anorectum in 4%. Among homosexual men with gonorrhea, anorectal infection occurs in 45%, although more than 90% of all male patients with anorectal gonorrhea admit to homosexual rectal intercourse. This infection is usually asymptomatic but occasionally presents with acute or chronic symptoms that mimic other causes of proctitis. Whereas currently recommended regimens for uncomplicated gonorrhea appear effective for anorectal gonorrhea in women, results in men have not been adequately evaluated. Available data showed failure rates from 7% to 35%; however, only one study used a currently accepted regimen. Further controlled studies in male patients with anorectal gonorrhea are clearly needed to establish optimal therapeutic regimens. Diligent contact tracing of all male homose.xual cases appears to be the only effective means of control at present.

Anti-Bacterial Agents↗
PubMed1977

Therapeutic regimens for anorectal gonococcal infection in males.

Anorectal gonococcal infection is particularly prevalent in women and homosexual men. Although the currently recommended Public Health Service therapeutic regimens for uncomplicated gonorrhea appear to be effective also for anorectal gonorrhea in women, their efficacy for anorectal infection in men has not been adequately evaluated. We report a case of gonococcal proctitis in a homosexual man that did not respond to therapy with ampicillin plus probenecid and tetracycline, but subsequently responded to spectinomycin therapy. Currently available therapeutic regimens for anorectal gonococcal infection in males are reviewed.

Adult↗
PubMed1975

Cephalothin and cephaloridine therapy for bacterial meningitis.

The efficacy of cephalothin and cephaloridine in the treatment of bacterial meningitis was evaluated from a review of 106 cases reported in the literature. Fifty-nine percent of 34 patients treated with intravenous cephalothin responded suboptimally; those receiving daily doses of 12 g or more fared significantly better (P less than 0.025). In contrast, 74% of 72 patients treated with cephaloridine responded favorably; those who received concomitant intrathecal cephaloridine responded significantly better (P less than 0.005). These findings indicate that cephalosporin therapy for bacterial meningitis, without concomitant intrathecal medication, is unreliable and that this is probably due to inadequate penetration of the antibiotics into cerebrospinal fluid. In penicillin-allergic patients with pneumococcal, meningococcal, and hemophilus meningitis, chloramphenicol is the agent of choice. For staphylococcal meningitis, intravenous cephalothin at doses of 12 g/day with additional intrathecal cephaloridine at doses of 12.5 to 50 mg/day should be administered concomitantly.

Bacterial Infections↗
PubMedDate not supplied

Case report. Failure of metronidazole in amebic liver abscess.

A 51-year-old man was treated with open surgical drainage and metronidazole for an amebic liver abscess. During therapy and while the original abscess was resolving, a second, noncontiguous amebic liver abscess developed. This second abscess eventually responded to emetine, chloroquine, and diodohydroxyquin therapy without surgical drainage. This unique case serves to document that new abscess may develop in the course of metronidazole therapy and illustrates the value of serial hepatoscanning in such patients.

Chloroquine↗