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Biomedical subjects

E Moses

Publications and source records attributed to E Moses.

At least 19 recordsLinked to original sources
PubMed1999

Pearling in cells: a clue to understanding cell shape.

Gradual disruption of the actin cytoskeleton induces a series of structural shape changes in cells leading to a transformation of cylindrical cell extensions into a periodic chain of "pearls." Quantitative measurements of the pearling instability give a square-root behavior for the wavelength as a function of drug concentration. We present a theory that explains these observations in terms of the interplay between rigidity of the submembranous actin shell and tension that is induced by boundary conditions set by adhesion points. The theory allows estimation of the rigidity and thickness of this supporting shell. The same theoretical considerations explain the shape of nonadherent edges in the general case of untreated cells.

Actins↗
PubMed1998

Dynamic excitations in membranes induced by optical tweezers.

We present the phenomenology of transformations in lipid bilayers that are excited by laser tweezers. A variety of dynamic instabilities and shape transformations are observed, including the pearling instability, expulsion of vesicles, and more exotic ones, such as the formation of passages. Our physical picture of the laser-membrane interaction is based on the generation of tension in the bilayer and loss of surface area. Although tension is the origin of the pearling instability, it does not suffice to explain expulsion of vesicles, where we observe opening of giant pores and creeping motion of bilayers. We present a quantitative theoretical framework to understand most of the observed phenomenology. The main hypothesis is that lipid is pulled into the optical trap by the familiar dielectric effect, is disrupted, and finally is repackaged into an optically unresolvable suspension of colloidal particles. This suspension, in turn, can produce osmotic pressure and depletion forces, driving the observed transformations.

Biophysical Phenomena↗
PubMed1998

Localized dynamic light scattering: a new approach to dynamic measurements in optical microscopy.

We present a new approach to probing single-particle dynamics that uses dynamic light scattering from a localized region. By scattering a focused laser beam from a micron-size particle, we measure its spatial fluctuations via the temporal autocorrelation of the scattered intensity. We demonstrate the applicability of this approach by measuring the three-dimensional force constants of a single bead and a pair of beads trapped by laser tweezers. The scattering equations that relate the scattered intensity autocorrelation to the particle position correlation function are derived. This technique has potential applications for measurement of biomolecular force constants and probing viscoelastic properties of complex media.

Biophysics↗
PubMed1992

Comparison of two culture approaches, blind passage and dual observation, for detecting Chlamydia trachomatis in various prevalence populations.

Chlamydia trachomatis diagnosis in our laboratory consisted of dual inoculation of shell vials and detection of inclusions by using fluorescein-conjugated monoclonal antiserum; the second culture vial was conventionally used for blind passage when the first vial was negative. We compared the increase in positivity using blind passage with that of a strategy utilizing observation of two stained monolayers (dual observation) without blind passage, in an effort to reduce the reporting time and labor associated with the conventional approach. A total of 4,329 specimens were obtained from an obstetrics and gynecology (OB-GYN) clinic (2,563 specimens) and the sexually transmitted disease clinic (1,766 specimens). These specimens were used to compare the two strategies. Blind passage of 1,269 initially culture-negative specimens from the OB-GYN clinic resulted in an additional 6 positive chlamydial diagnoses. In comparison, a similar number of specimens (1,294) from the OB-GYN clinic collected subsequently to the first group were tested by dual observation. There were five additional positive findings. A similar evaluation of specimens from the sexually transmitted disease clinic was performed. Blind passage of 313 initially culture-negative specimens yielded 3 additional positive diagnoses, whereas dual observation of 1,435 similar specimens resulted in 9 positive diagnoses. On the basis of analysis of 4,332 specimens, sensitivity of dual observation is comparable to that of blind passage; labor, cost, and reporting time of dual observation are reduced in comparison to those of blind passage.

Bacteriological Techniques↗
PubMed1991

Evaluation of a visual, rapid, membrane enzyme immunoassay for the detection of herpes simplex virus antigen.

We evaluated a 12-min, direct, monoclonal antibody-based enzyme immunoassay (EIA) (SureCell; Kodak, Rochester, N.Y.) which aids in the detection of herpes simplex virus infection; the assay system is also approved for culture confirmation. The test was evaluated from direct clinical samples and compared with conventional culture methodology by using a single swab. A total of 265 specimens from 180 female cervical-urogenital sites, 62 male urogenital sites, 4 rectal sites, 3 skin sites, 6 oral sites, and 10 colposcopy sites were collected on Dacron or cotton swabs and placed in viral transport medium (VTM). Within 6 h of receipt, 0.2 ml of the vortexed VTM was inoculated into each of two replicate cell cultures. Cell monolayers were observed daily for ten days, and cytopathic effect was confirmed by using an indirect immunoperoxidase reagent. The procedure for the SureCell assay conformed to the manufacturer's recommendations. When conventional culture was compared with EIA results, the overall sensitivity, specificity, positive predictive value, negative predictive value, and agreement were 64.4, 98.9, 96.7, 84.4, and 87.2%, respectively. Variables affecting the EIA sensitivity are the stage of the lesion and conventional culture methodologies. A review of culture results for 32 EIA false-negative tests indicated that 15 were detected after 48 h of incubation. Cytopathic effect observed at 48-, 72-, and 96-h cutoffs altered the sensitivity for the EIA. To ensure detection of SureCell herpes simplex virus-negative specimens, it is recommended that an unused aliquot of VTM be tested in cell culture.

Antigens, Viral↗
PubMed1991

[Overexpression of an extracellular Bacteroides nodosus protease in E. coli and isolation and characterization of its promoter].

Bacteroides nodosus is the essential causative agent of ovine footrot. It produces extracellular proteases which involved in pathogenesis of footrot. In this paper, we report the subcloning of Bacteroides nodosus protease, its overexpression in E. coli and its N-terminal polypeptide sequence. The subclone library was constructed in E. coli using SphI digested original clone (15 kb) and plasmid PTZ18R and screened using immunological assay. The expression was observed using SDS-PAGE. The subcloned DNA fragment was then cut with Sau3AI, cloned into pKK232-8 vector to perform promoter isolation and analysis. The promoter strength was determined using spectrophotometric assay.

Bacteroides↗
PubMed1989

Common variable immunodeficiency: a family study and therapeutic trial with cimetidine.

Various immunologic parameters were tested in a family of two patients with common variable immunodeficiency. Both patients had low serum immunoglobulin levels, low peripheral B cell and T4 subclass of lymphocytes, and reversed T4/T8 ratio. One of the patients had excessive suppressor activity. Two of the asymptomatic members of the family (the father and one brother) had also low T4/T8 ratio that was not associated with excessive suppressor activity. No linkage between the disease inheritance to HLA could be observed. A study of the T cell helper activity to an antigen, the response to which is regulated by an HLA-linked gene, suggested a defect in the immune response of the two patients and their asymptomatic brother with immunologic disorders. Treatment with cimetidine of the patient with excessive suppressor activity led to an improvement in his clinical state, reduction in suppressor activity, temporary effect on his proliferative response capacity to mitogens, and an increase in the antigen-specific helper activity.

Adult↗
PubMed1989

Phosphorylation of superior cervical ganglion proteins during regeneration.

The incorporation of radioactive phosphate into proteins of both normal and regenerating ganglia of the sympathetic nervous system of the rat is reported. The incorporation reactions were carried out in vitro by incubating homogenates of excised ganglia with [gamma-32P]ATP under various conditions. It was found that incorporation of phosphate into proteins of regenerating ganglia in the molecular mass range 10,000-100,000 daltons increased up to 40% over incorporation into proteins from control ganglia during the first 3 days following injury and returned to control levels after 14 days. Analysis of the proteins by two-dimensional electrophoresis revealed that only few, i.e., less than 20, became radioactively labelled in homogenates of superior cervical ganglia in the presence of Ca2+, and even fewer in the presence of cyclic AMP. Furthermore, all these proteins fell within a narrow pI range of 4-6. The growth-associated protein, variously designated GAP-43, B-50, F-1, and pp46, has an enhanced level of expression and phosphorylation in regenerating ganglia compared with controls at day 3. Injury also caused consistently higher levels of incorporation into two other proteins with molecular masses at positions 55,000 and 85,000 and pI values of 5.1 and 4.5, respectively; the former protein most probably is beta-tubulin. The fact that both proteins are found in the 15,000 g pellet after the tissue has been solubilized in 0.5% nonionic detergent indicates that they may indeed by components of filament assemblies. Thus, the results suggest that protein phosphorylation is a mechanism involved in cytoskeletal function in regenerating nerve.

Adenosine Triphosphate↗