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Biomedical subjects

M Ruben

Publications and source records attributed to M Ruben.

At least 19 recordsLinked to original sources
PubMed1988

Regulated expression of a transfected human cardiac actin gene during differentiation of multipotential murine embryonal carcinoma cells.

P19 embryonal carcinoma (EC) cells are multipotential stem cells which can be induced to differentiate in vitro into a variety of cell types, including cardiac muscle cells. A cloned human cardiac actin (CH-actin) gene was transfected into P19 cells, and stable transformants were isolated. Low levels of CH-actin mRNA were present in transformed EC cells, but a marked increase in the level of CH-actin mRNA was found as these cells differentiated into cardiac muscle. The accumulation of CH-actin mRNA paralleled that of the endogenous mouse cardiac actin mRNA. A chimeric gene, which consisted of the CH-actin promoter linked to the herpes simplex virus thymidine kinase coding region, was constructed and transfected into P19 cells. In these transformants, the thymidine kinase protein was located almost exclusively in cardiac muscle cells and was generally not detectable in EC or other nonmuscle cells. These results suggest that the transfected CH-actin promoter functions in the appropriate developmental and tissue-specific manner during the differentiation of multipotential EC cells in culture.

Actins↗
PubMed1986

An integrated software system for microcomputer management of recombinant DNA data.

A database-oriented system (pCP123) is described for the manipulation of recombinant DNA data. This system was developed within the context of an integrated software package with spreadsheet, database, graphing and programming capabilities. The system includes two databases, one of sites and another of regions, coordinately handled by a series of macro-programs operated from four user-define menus. A distinctive feature of the system is the possibility of handling both ends of defined functional or structural regions in situations of simulated deletions or insertions.

Computers↗
PubMed1984

Contact lenses.

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Aged↗
PubMed1984

Corneal epithelial response of the primate eye to gas permeable corneal contact lenses: a preliminary report.

The comparative corneal epithelial effects of rigid gas permeable and soft contact lenses are reported in the present preliminary study using two bush baby monkeys (Galago senegalensis). Both types of lenses produced early cell death among the surface squamous cells while internally the epithelium and its nerve fibers remained normal. Sporadically small abnormal groups of cells involving two to three of the surface layers were observed in both the hard and soft lens wearing corneas. It was concluded that this represented superficial punctate keratitis (SPK). Small superficial intracellular epithelial cysts with membranous contents were infrequently noted in the gas permeable lens wearing cornea and it is suggested here that they were mild forms or precursors of those seen clinically in human corneas. Since the gas permeable lens met the corneal oxygen requirement it is postulated that the traumatic effect of the rigidity of the lens caused the cystic formation to occur. The relative hypoxia induced by the soft contact lens resulted in a mild superficial epithelial edema.

Animals↗
PubMed1983

Covalently closed circles of adenovirus 5 DNA.

The genome of adenoviruses is a double-stranded linear DNA molecule with inverted terminal repeats about 100 base pairs (bp) in length and a terminal protein covalently linked to the 5' nucleotide of each strand. Both of these features permit the formation of DNA circles, the inverted repeats allowing the circularization of single-stranded DNA and the terminal protein the joining of one or more molecules to yield double-stranded circles or concatemers. However, although the existence of covalently closed circles has been postulated, double-stranded viral DNA purified from virions or infected cells by conventional methods (that is, using proteases and phenol or chloroform) has always been obtained in a linear form. Here, we present evidence for the existence in adenovirus 5 (Ad5) infected cells of novel structures resulting from covalent head-to-tail joining of viral DNA molecules and show that these structures are due at least in part to the formation of covalently closed circles.

Adenoviridae↗
PubMed1982

Integration and expression of viral DNA in cells transformed by host range mutants of adenovirus type 5.

Group I host range (hr) mutants of adenovirus type 5 are unable to transform rat embryo or rat embryo brain cells but induce an abnormal transformation of baby rat kidney cells. We established several transformed rat kidney cell lines and characterized them with respect to the transformed phenotype and the structure of the integrated viral DNA. The hr mutant-transformed cells, unlike wild-type virus transformants, were fibroblastic rather than epithelial, failed to grow in soft agar, and were also less tumorigenic in nude mice. Studies on the structure of the integrated viral DNA sequences showed that hr-transformed cells always contained the left end of the adenovirus DNA, but the size of the integrated DNA fragment varied among different lines, and a high percentage of the lines contained the entire viral genome colinearly integrated. The patterns of integration were maintained after prolonged growth in culture and after subcloning. Attempts to rescue infectious virus from lines which contained the entire genome were unsuccessful. Using immunoprecipitation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, we analyzed the viral proteins expressed in hr-transformed cells. Results of these studies indicated that, like wild type-transformed cells, hr transformants expressed E1B proteins of molecular weight 58,000 and 19,000.

Adenoviridae↗
PubMed1981

Clinical aspects of the measurement of oxygen flux into the cornea.

A comparison was firstly done of the oxygen flux through the Bausch and Lomb Plano T lens, the Bausch & Lomb U3 lens, and the Duragel 75 lens with a sensor on the normal eye. The results showed that the Bausch and Lomb Plano T lens was the best for use with the sensor probe. The sensor was then used to obtain a comparison with the normal oxygen flux through a therapeutic lens on keratoplastic eyes and eyes with bullous keratopathy. The results showed that both conditions had a lower oxygen consumption than normal and that eyes with bullous keratopathy predictably had the lowest value.

Contact Lenses, Hydrophilic↗
PubMed1980

Penetration of mercury from ophthalmic preservatives into the human eye.

Single corneas of nine patients about to undergo full-thickness corneal keratoplasty were exposed to thiomersal by application of a hydrophilic gel contact lens preserved with this mercurial agent. These lenses were removed at operation 4 h later, and the lenses, corneal buttons, and samples of aqueous were taken for determination of total mercury by wet digestion and flameless atomic absorption. The contact lenses contained little residual mercury, but mercury was readily detected in the corneal buttons and in the samples of aqueous over the range of 1--60 ng/ml. Five control samples of aqueous obtained without exposure to mercurial preservatives contained less than 1 ng/ml mercury. Although specific effects on ocular function are not described, the use of these preservatives is associated with penetration of mercury into the aqueous in concentration similar to those reported with systemic poisoning by organic mercurials.

Aqueous Humor↗
PubMed1980

The pathology of soft contact lens spoilage.

Our study of a random series of more than 300 spoiled soft contact lenses reveals that virtually all lenses currently in use for daily or extended wear are subject to deterioration due to extraneous deposits, physical and chemical changes in the lens material, and microbial invasion. Common causes include ocular secretions, finger dirt and cosmetics, disinfecting and cleansing techniques, environmental factors, manufacturing defects and polymer impurities, mechanical stress and breakage, as well as aging and decay of the lens material. Mucoprotein-lipid deposits, with or without calcium, and calcareous deposits constitute the major forms of lens spoilage. Removal of encrusted deposits leaves surface irregularities and matrix defects which facilitate secondary spoilage including microbial invasion, and such lenses should be discarded. As virtually no soft lens material currently in use is "safe" for extended wear, the practitioner must carefully evaluated and follow his patients to identify those at risk of lens failure and spoilage complications. To eliminate spoilage, new lens materials and improved manufacturing techniques are needed. In the interim, for many patients, an inexpensive disposable soft lens which can be easily replaced, perhaps weekly or bi-weekly, may be the answer.

Acrylates↗
PubMed1979

Keratoconus, keratoplasty thickness, and endothelial morphology.

A group of successful keratonic grafts (51 eyes) up to 10 years from operation were examined to establish a relationship between graft thickness and acuity. Best acuity occurred in the grafts of normal corneal thickness. No grafts were thinner than normal; thus no tendency to keratonic thinning occurred. No relationship between age of graft and thickness was determined. Endothelial cell studies in vivo of a small number of grafts showed that cell counts a third of normal coexisted with normal acuity and corneal thickness.

Cornea↗
PubMed1979

Keratoplasty sensitivity.

Analysis of graft sensitivity showed a return to normal after 3 years in only one-third of the eyes. It is not known whether this is due to regeneration of abnormal or superficial nerve fibres. Contact lens wearers showed less sensitivity than spectacle wearers.

Contact Lenses↗