Biomedical subjects

J C Merriam

Publications and source records attributed to J C Merriam.

31 records · Page 2Linked to original sources

PubMed1992

Radiation retinopathy: electron microscopy of retina and optic nerve.

A 4 1/2 year old female was treated for embryonal rhabdomyosarcoma of the left orbit in 1975 with radiation (59.5 Gy in 5 weeks), followed by chemotherapy. An electroretinogram (ERG) in March, 1988 revealed cone responses 3% of normal and no rod responses in the left eye, and normal responses in the right eye. The eye was enucleated in April 1988. In the fovea no choroidocapillaris was seen at the intact Bruch's membrane, and the pigment epithelium was preserved only in small patches. No photoreceptor cells were seen in the areas devoid of pigment epithelial cells. The parafoveal and peripheral (30 degrees eccentricity) retina was better preserved. The thickness of the layer of rods and cones and of Henle's fiber layer was reduced. Very few outer segments were present. Macrophages had invaded the retinal tissue in moderate numbers. The retinal vessels were ensheathed by several layers of collagen fibrils. The spatial densities of pigment epithelial, cone, rod, and bipolar cells had been reduced. The optic nerve contained a total number of 1,022,000 nerve fibers.

Child, Preschool↗

PubMed1991

Evidence of genotoxic damage in human cataractous lenses.

Lens epithelial fragments (tags) recovered from individuals during routine cataract extraction have been assessed for cellular changes reflective of genotoxic damage. A high percentage of tags exhibited a population of micronucleated and polyploid cells. The presence and number of micronuclei (MN) in the epithelia of cataract patients appears to be independent of age and sex. However, a large number of MN in the epithelial cells of some individuals strongly suggests a history of compromised genomic integrity. While the study was not designed to define the role of DNA damage in the development of cataracts or to monitor human populations at risk of exposure to exogenous mutagens/cataractogens, the potential of the methodology to address each is demonstrated.

Adult↗

PubMed1988

Reconstruction of the lids of a child with microblepharon and multiple congenital anomalies.

The initial stages in the rehabilitation of a male child with severe microblepharon, corneal opacities, bilateral facial clefts, bilateral complete cleft lip and palate, and unilateral syndactyly are described. Review of the literature suggests that severe microblepharon is associated with other craniofacial anomalies, and often the child is stillborn or retarded. Surviving children have been abandoned because of their appearance. The child described in this case appears to be unique because his intelligence is normal, and, to our knowledge, this is the first reported case of penetrating keratoplasty after reconstruction of functional eyelids. The principal problems after corneal grafting appear to have been chronic partial exposure due to inadequate lid length and a poor Bell's reflex and the persistence of a rim of vascularized fibrous tissue around the corneal graft. Future reconstructive surgery is outlined.

Cleft Lip↗

PubMed1984

Toxicity of a monoclonal F(ab')2:ricin A conjugate for retinoblastoma in vitro.

The toxic A chain of the poison ricin has been conjugated to the F(ab')2 fragment of a retinoblastoma-specific murine monoclonal antibody. The conjugate was toxic in vitro to Y-79 retinoblastoma cells at a concentration of approximately 5 X 10(-10) M; Y-79 retinoblastoma cells were the immunizing cells in the production of the monoclonal antibody. Against a second retinoblastoma cell line, the conjugate was toxic at a concentration of approximately 10(-9) M. Ricin A chain alone was not toxic to either of these cell lines at concentrations less than 4 X 10(-8) M. The conjugate was no more toxic than was ricin A chain against five control cell lines in vitro. The effect of the conjugate on retinoblastoma-derived cells was concentration dependent. Concentrations less than a "minimum" concentration were not cytotoxic, despite an excess of conjugate molecules over target cells. Concentrations greater than the minimum toxic concentration rapidly reached maximal toxicity, suggesting that antigenic sites were saturated. No clinical, hematologic, or renal toxicity was noted when mice were given injections of the conjugate at 1 mg/kg, or free ricin A chain at 0.375 mg/kg.

Antibodies, Monoclonal↗

PubMed1983

Early-onset pauciarticular juvenile rheumatoid arthritis. A histopathologic study.

A young girl with early-onset pauciarticular juvenile rheumatoid arthritis suffered from recurrent severe bilateral iridocyclitis. Despite intensive medical therapy, she gradually lost all useful vision and ultimately required bilateral enucleation at the age of 10 years for control of pain and photophobia. Histopathologic study of the eyes revealed in the iris and ciliary body a dense inflammatory infiltrate composed principally of plasma cells, as well as angle closure, a dense cyclitic membrane, retinal detachment, cystoid macula, and optic atrophy. Immunoperoxidase stains showed little immunoglobulin within or around the plasma cells within the ciliary body, although strong reactions for IgG and kappa- and lambda-light chains were seen in other parts of the eyes.

Arthritis, Juvenile↗

PubMed1979

Morphology and pathogenesis of adrenal cysts.

Adrenal cysts represent a rare condition (approximately 250 cases have been reported). We report two additional cases: the first involved a huge lesion removed surgically and thoroughly studied preoperatively; the second was an incidental autopsy finding. Detailed ultrastructural studies have been made of both cases. We think that the basic cell of origin of the cyst is an endothelial cell lining lymphatic channels. We speculate that the pseudocysts, which have been described as having a fibrous lining, probably were at one time also lymphendothelial but, perhaps due to trauma or repeated bleeding, the major portion of the endothelial lining became replaced by collagen. The primary and secondary cystic malignancies and cases of cysts due to parasites should be classified separately from the adrenal cysts of lymphendothelial origin which probably represent a benign tumor-like overgrowth.

Adrenal Gland Diseases↗

PubMed1978

Prolonged survival of alymphatic skin allografts in the rat. A humoral component.

Immunological mechanisms of increased graft survival in "immunologically privileged" sites were defined by comparing host responses against orthotopic and alymphatic skin allografts in rats. The conventional skin grafts reject by day 8; grafts placed on alymphatic skin pedicles heal in normally, but begin by day 16 to 18 to contract inexorably until only a scar remains by day 35 to 40. Lymphocyte-mediated cytotoxicity rose significantly in spleen and draining lymph nodes 8 to 10 days after orthotopic grafting, but was absent as long as 35 days after skin transplantation to alymphatic pedicles. No significant activity in antibody-dependent lymphocyte-mediated cytotoxicity was noted in either recipient group, while complement-dependent cytotoxicity was slightly elevated 8 to 10 days postoperatively in both groups. Passive transfer of serum from recipients of alymphatic skin grafts, taken 8 and 12 days after grafting, prolonged survival of test cardiac allografts significantly, although neither control serum from recipients of orthotopic skin allografts, or serum taken 28 days after alymphatic skin grafting increased test heart survival. We conclude that prolonged survival of skin grafts on alymphatic sites may be based, at least partially, on the development of host humoral factors.

Animals↗

PubMed1976