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Biomedical subjects

K L Cohen

Publications and source records attributed to K L Cohen.

At least 55 records · Page 3Linked to original sources
PubMed1984

Effect of tissue fit on corneal shape after transplantation.

Postkeratoplasty astigmatism is now a major problem preventing visual recovery. Certain postoperative topographic characteristics are felt to be dictated by the fit of the donor corneal button in its recipient bed. Deficient tissue at the wound is predicted to contribute to the location of the steep meridian and excess tissue to the location of the flat meridian. In an eight-cat sample using our Fit Assessment Method and Photogrammetric Index Method, the authors tested the relationship between button fit in recipient bed and resulting corneal curvature at approximately 42, 161, and 289 postoperative days. Corneal symmetry improved between the first and second postoperative periods. Deficient tissue led to steepened curvature and ample tissue to flattened curvature in the first measurement period. When buttons fit poorly, deficient tissue led to steepness in the first postoperative period, but led to flattened curvature 90 deg away from the deficient tissue meridian in the second and third periods. The relationship between ample tissue and flattest postoperative curvature did not depend on the magnitude of button-fed disparity in any period. Corneal elasticity appeared to influence the way tissue disparity affected postoperative topography. Our findings support Troutman's balloon mode. When there was a large amount of uncompensated tissue disparity, the tissue deficiency exerted a force that shortened the translimbal chord. This produced both steepened curvature parallel to this chord soon after surgery and flattened curvature at 90 deg to the chord in the stable postoperative cornea.

Animals↗
PubMed1984

A new photogrammetric method for quantifying corneal topography.

Attempts to describe normal corneal shape and to represent corneal topography by an array of discrete points have limited usefulness. A quantitative photogrammetric method that produces indices to describe corneal shape was developed. Four indices depict the departure of keratographic rings from circularity, and two indices express the trends and consistencies of all the rings from one keratograph. This photogrammetric index method (PIM) was evaluated against established measurement techniques. Values for the six indices were computed for groups (10 corneas each) of symmetrical, regularly astigmatic, and keratoconic corneas that had been defined by keratometry and clinical criteria. Predictions of the differences among groups were formulated for each index based on group descriptions and anticipated manual tracing and/or digitization error. Parametric and nonparametric tests of significance supported most predictions. The asymmetry of irregularly astigmatic keratoconic corneas, the variability of their orthogonal principal meridians, and an increasing symmetry toward their peripheries were documented clearly. The circularity of symmetrical group rings and the ellipticity of regularly astigmatic group rings were also evident. Preliminary norms are offered to illustrate the usefulness of the PIM in defining groups of corneas with the same histories and in classifying individual corneas.

Adult↗
PubMed1983

Episcleral and orbital pseudorheumatoid nodules.

Pseudorheumatoid nodules are subcutaneous necrobiotic granulomas that are histopathologically similar or identical to those seen with rheumatoid arthritis, granuloma annulare, necrobiosis lipoidica diabeticorum, and systemic lupus erythematosus. Although these nodules are most common in children, they are also seen in adults and are usually located on the extremities and scalp. Eyelid and eyebrow involvement is seen infrequently. We histopathologically verified episcleral and orbital pseudorheumatoid nodules in an adult with eyelid and eyebrow nodules. Pseudorheumatoid nodules must be included in the differential diagnosis of subconjunctival mass lesions that may concomitantly involve the orbit, episclera, and periocular region.

Adult↗
PubMed1982

Primary lymphoma of the spinal cord.

Lymphomas may occur in the central nervous system either as primary lesions or secondary to lymphomas in other sites. While lymphomas secondary to generalized lymphoproliferation may occur in either the brain or the spinal cord, primary lymphomas are found almost exclusively in the brain. Only three primary lymphomas of the cord have been reported. We recently had the opportunity to study a fourth case. Spinal cord lymphoma was not the diagnosis considered in any of these cases. Since the lesion is radiosensitive, inclusion of primary lymphoma in the differential diagnosis of obscure spinal cord tumors could result in a histological diagnosis and effective therapy.

Diagnosis, Differential↗
PubMed1982

Sterile corneal perforation after cataract surgery in Sjögren's syndrome.

Painless, sterile, noninfiltrated corneal ulceration and perforation, which may occur after recent cataract surgery in patients with rheumatoid arthritis, and Sjögren's syndrome, appears to be a distinct clinical entity. The cause is probably multifactorial. Contributing factors may be the underlying systemic disease process in rheumatoid arthritis and Sjögren's syndrome, the associated keratoconjunctivitis sicca, the surgical procedure, and the postoperative use of oral and topical corticosteroids. Two cases of this clinical entity are reported here. Preoperative recognition by cataract surgeons that corneas in patients with rheumatoid arthritis and Sjögren's syndrome have an increased risk for postoperative ulceration should prompt postoperative preventive measures.

Aged↗
PubMed1981

Sarcoidosis and ocular disease in a young child. A case report and review of the literature.

Uveitis in the very young child may be a manifestation of sarcoidosis. A case of sarcoidosis with intraocular inflammation that occurred in a child 2 years 7 months old is reported. The diagnosis was supported by biopsy of uncommon bulbar conjunctival nodules. Knowledge by the ophthalmologists that this disease can occur in children younger than 5 years of age may be crucial to the establishment of proper diagnosis.

Biopsy↗
PubMed1981

Mucinous sweat gland adenocarcinoma of the eyelid.

A 62-year-old woman developed a recurrent mucinous sweat gland adenocarcinoma of the eyelid. The clinical characteristics of this rare, primary adnexal neoplasm of skin in our patient were, to our knowledge, unique. The tumor mimicked a lacrimal sac tumor and had orbital extension demonstrated preoperatively by computed axial tomography. Orbital extension of the tumor mass was confirmed during a wide, en bloc, excisional biopsy.

Adenocarcinoma↗
PubMed1981

Specular microscopic observations of clinically normal feline corneal endothelium.

Endothelial specular microscopy and pachometry were performed on right and left eyes of 11 anesthetized young adult American Shorthair cats with clinically normal eyes. Endothelial cells of the central cornea formed a mosaic-like pattern of hexagonal cells 15 to 20 microns in diameter; the average number of cells per millimeter2 was 2,668 +/- 211 SD. Corneal thickness was 0.56 mm +/- 0.06 SD.

Animals↗
PubMed1980

Haemophilus influenzae ophthalmia neonatorum.

Haemophilus influenzae is an occasional cause of ophthalmia neonatorum. Recently, this organism has exhibited a change in its epidemiology and has been identified as a cause of severe neonatal infections. Ophthalmologists should be aware of the changing susceptibility of neonates to severe infections with H influenzae and the possibility that H influenzae ophthalmia neonatorum can be associated with these infections.

Antibodies, Bacterial↗
PubMed1980

Cohn fraction VI enhances the growth stimulating effect of Multiplication Stimulating Activity (MSA) on chick embryo fibroblasts in culture.

Although the somatomedin polypeptides stimulate the growth of cells in vitro, the magnitude of this effect is less than that of whole serum. We have investigated the possibility that serum may contain a factor(s) which would enhance the mitogenic response of cells in tissue culture to purified MSA (Multiplication Stimulating Activity), a somatomedin-like polypeptide. MSA alone is unable to achieve the full stimulating effect of serum on cultured chick embryo fibroblasts (CEF). However, Cohn Fraction VI prepared from human serum greatly enhances the ability of MSA to stimulate DNA synthesis and cell multiplication in CEF. This activity is not accounted for by the three major components of fraction VI-albumin, alpha, acid glycoprotein, and alpha2 acid glycoprotein. The factor is heat stable and has an apparent molecular weight of 1000-1500. Brief exposure of CEF to the factor prior to the addition of MSA is sufficient for enhancement to occur. In addition, the factor also enhances the stimulation of (3H) thymidine incorporation in CEF by insulin. This factor may modulate the cellular response to diverse insulin-like peptides.

Animals↗
PubMed1979

Thyroid function screening in psychiatric patients.

Abnormalities in levels of total thyroxine and thyroxine binding capacity were common in a group of 480 newly admitted psychiatric patients. The estimated free thyroxine (EFT4) level was elevated in 43 patients (9%). In 27 of these patients, the level of EFT4 became spontaneously normal, usually within a two-week period (acute "stress hyperthyroidism"). The level of EFT4 was decreased in 42 patients (9%). In 16 of these patients, the level became spontaneously normal; the etiology of this apparent acute hypolhyroidism is unclear. The yield of new cases of primary hyperthyroidism and hypothyroidism was low, but a presumptive diagnosis of secondary hypothyroidism was made in eight patients. In addition, nine patients with known thyroid disease were taking inadequate or excessive replacement therapy. Thyroid function screening tests are of value in psychiatric patients.

Adolescent↗