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Biomedical subjects

M Yanoff

Publications and source records attributed to M Yanoff.

At least 19 recordsLinked to original sources
PubMed1992

Comparison and characterization of retinal pericytes and retinal pigment epithelial cells on subcellular IP3-sensitive Ca2+ pools.

A comparative study of inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ mobilization in bovine retinal capillary pericytes (BRCP) and bovine retinal pigment epithelial cells (BRPE) was carried out. Both cells were permeabilized with saponin. The two cell types had similar basal levels of [Ca2+]i (130 nM for BRCP, 132 nM for BRPE) and responded to IP3 in a dose-dependent manner. However, when stimulated by various concentrations of IP3 (1-10 microM), the increase in [Ca2+]i of BRCP was always two- to threefold higher than that in BRPE. Subcellular-fractionation studies showed that a single population of IP3 binding site with a high affinity and high specificity of IP3 mainly localized to plasma membrane in these two cell types. Although the dissociation constant of specific [32P]-IP3 binding sites (Kd 1.9-2.8 nM) was similar, the profile of maximal binding capacity (Bmax) of each fraction was markedly different. In comparison, plasma membrane fractions of BRCP were with Bmax of 165 fmol/mg protein versus 90 fmol/mg protein for BRPE membranes. The ATP-dependent Ca2+ uptake and IP3-dependent Ca2+ release were observed in the both plasma membrane fractions. With quantitative correlation, the membrane fraction (2 mg) of BRCP released 0.2 nmol Ca2+ whereas BRPE only released 0.07 nmol Ca2+ with the same dose of IP3 (5 microM). The selectively higher density of IP3 binding sites in coupling to the larger Ca(2+)-release in the membrane of BRCP suggests that the quantity of Ca2+ mobilized is determined by the spatially preferential distribution of membrane-associated IP3 binding sites. These findings may provide an explanation for the differences observed between BRCP and BRPE in IP3-induced DNA replication.

Binding Sites↗
PubMed1992

Reciprocal corneal transplantation fails to correct mucopolysaccharidosis VI corneal storage.

This report contains the results of studies designed to evaluate corneal clearing in mucopolysaccharidosis VI (MPS VI)-affected cats. Corneal buttons from affected cats were transplanted into normal cat corneas and, as controls, normal-to-normal and normal-to-affected transplants also were done. No clearing of the MPS VI graft or host beds occurred, nor was there any clouding of the normal donor or recipient corneal tissues. This assessment was made by serial clinical examinations over a 14-30 mo period and by light and electron microscopic examination of the corneal tissues at the end of the study. Lack of corneal clearing under conditions that would maximize such a process in this animal model indicates that corneal clearing is not an appropriate index for measuring the success of systemic therapy in MPS VI.

Animals↗
PubMed1991

Subconjunctival anesthesia: an alternative to retrobulbar and peribulbar techniques.

We present a method of anesthesia for intraocular surgery of the anterior segment of the eye that avoids the risks of the potential complications associated with retrobulbar and peribulbar anesthesia. The method consists of topical anesthesia plus 0.5 cc of lidocaine (with hyaluronidase and epinephrine) injected beneath the superior conjunctiva. We have demonstrated the safety and effectiveness of this technique in 431 consecutive cases.

Anesthesia, Local↗
PubMed1990

A 32-year follow-up of the rigid Schreck anterior chamber lens. A clinicopathological correlation.

We describe the clinicopathological findings in an eye after 32 years of successful anterior chamber lens implantation. In 1956, a rigid Schreck total polymethylmethacrylate anterior chamber lens was implanted in the right eye of a 28-year-old white man 1 year after corneo-scleral laceration with traumatic cataract. The postoperative clinical course was subjectively unremarkable for at least 30 years. In 1988, the patient developed secondary angle closure glaucoma, associated with a cavernous Schnabel optic atrophy that was caused by peripheral anterior synechiae and fibrovascular downgrowth into the anterior chamber. The lens implant was encapsulated "cocoonlike." Secondary proliferation of corneal endothelial cells covered the fibrous membrane and the chamber angle structures. No inflammatory reaction and only a very slight foreign-body reaction in the area of the footplate of the anterior chamber lens were present. Clinical and histopathological findings indicate that polymethylmethacrylate is sufficiently inert and biocompatible to be tolerated by the surrounding ocular tissues for more than 30 years.

Anterior Chamber↗
PubMed1990

Anterior eyewall perforation during subconjunctival cataract block.

A patient was given a new type of subconjunctival block in preparation for cataract surgery. During the insertion of the needle subconjunctivally, the anterior eyewall was inadvertently perforated, resulting in a tiny retinal tear and focal retinal detachment. The cataract surgery, including intraocular lens implantation, was carried out without further problems. The retinal tear and tiny detachment were repaired the next day by argon laser photocoagulation. The visual result was excellent. To our knowledge, this is the first report of anterior eyewall perforation occurring with the use of this new subconjunctival anesthetic block.

Aged↗
PubMed1989

[Configuration of corneal incisions with the excimer laser: an experimental study].

The potential applications of an ophthalmic excimer laser at 193 nm include its use as a precise trephine in keratoplasty procedures. In a series of 20 human autopsy and 40 pig cadaver eyes the histological and ultrastructural results of donor and recipient trephination and full-thickness corneal grafting using new mask systems were evaluated. In comparison with other beam delivery systems the "open mask system" allows the performance of excimer laser trephinations with reproducible wound configuration and geometry, with easy handling and high reliability. This technique enables the surgeon to surmount the mechanical limitations of cutting direction and makes non-circular trephinations possible.

Animals↗
PubMed1989

Excimer laser keratoplasty. Part 2: Elliptical keratoplasty.

An excimer laser at 193 nm was used with a new "open mask system" to perform elliptical noncontact and nonthermal keratoplasties and corneal grafts in human cadaver eyes (Part 1 of this article, Ophthalmic Surg 1989; 20:262-267). By light microscopy the corneas showed sharp, unbeveled cut margins with nearly perfect apposition of the inner wound aspects. An elliptical shape may be better than a circular one, since the former closely approximates the cornea's normal elliptical outline, making it easier to fit corresponding areas of corneal graft to bed. Also, it provides a wider area of Bowman's membrane for anchoring sutures and relatively less volume of donor antigenic tissue.

Cadaver↗
PubMed1989

Excimer laser keratoplasty. Part 1: Basic concepts.

A commercially available ophthalmic excimer laser was used with a new "open mask system" to perform noncontact and nonthermal excimer laser keratoplasty in 20 human and 40 pig cadaver eyes. Circular penetrating corneal trephinations and corneal grafts were performed with the excimer laser set at 193 nm. Light microscopy and scanning and transmission electron microscopy of the human and pig eyes demonstrated the high quality of excimer laser trephination (smooth wound margins that were approximately parallel to the optical axis of the eye), and the superior wound configuration and geometry.

Animals↗
PubMed1988

Intraocular pressure in exfoliation syndrome.

Two studies, both retrospective, were done at our institution. The first study evaluated 100 consecutive patients with exfoliation (EX) syndrome found as an incidental finding in a private, general ophthalmology practice, to determine the incidence of glaucoma. The second determined the long-term course of EX as it relates to the onset of elevated intraocular pressure (IOP). In the first study, of 124 eyes having EX 78% had normal IOP, 15% had intraocular pressure greater than 22 mm Hg but no cupping or field loss (ocular hypertension or glaucoma suspect), and 7% had glaucoma. In the second study 347 patients who initially had normal IOPs and either unilateral or bilateral EX were followed over time. Elevated IOP developed in 35 patients (44 eyes) during the study. The cumulative probability for eyes with EX to develop elevated intraocular pressure was 5.3% in 5 years and increased to 15.4% in 10 years. These probabilities predict that patients with EX have a higher incidence of developing elevated intraocular pressure than would be expected in patients without EX of similar age.

Aged↗
PubMed1987

Inverted follicular keratosis. A report of two recurrent cases.

Few cases of recurrent inverted follicular keratosis (IFK) have been reported in the literature, none with histopathologic confirmation. The authors report two cases of IFK that recurred within weeks of primary excision. Histologic confirmation was obtained on all four specimens. By establishing the benign nature of the recurrent lesions, unnecessary, possibly drastic surgery was avoided.

Aged↗