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Biomedical subjects

K B Simons

Publications and source records attributed to K B Simons.

29 records · Page 2Linked to original sources
PubMed1985

Intracameral administration of alpha-MSH increases intraocular pressure in rabbits.

A growing body of evidence suggests that neural peptides may induce important modulations on vegative and motor functions of the eye. The present study was designed to evaluate the effect of intracameral (I.C.) administration of alpha-melanocyte-stimulating hormone (alpha-MSH) and several other ocular peptides on intraocular pressure (IOP) in rabbits. alpha-MSH (5 micrograms) produced a significant and prolonged unilateral increase of IOP. This effect of I.C. alpha-MSH was dose-dependent (ED50 = 2.5 micrograms). Structure-activity studies revealed that equimolar doses of beta-MSH and gamma-MSH, unlike alpha-MSH, were totally ineffective. In addition, the structurally unrelated peptides beta-endorphin, thyrotropin-releasing hormone (TRH) and gonadotropin-releasing hormone (Gn-RH) did not affect IOP, when tested in a dose equimolar to 5 micrograms of alpha-MSH. These results confirm and extend previous observations, suggesting that alpha-MSH may be an important factor involved in regulation of IOP.

Animals↗
PubMed1985

Pupillary effects of neurotensin: structure-activity relationships.

We have previously reported that intracameral (I.C.) administration of neurotensin (NT) potently induces a time- and dose-dependent miosis in rabbits. This study was designed to determine structure-function relationships for NT-induced miosis. NT and twelve different fragments and analogs of NT, and the structurally-unrelated peptides beta-endorphin (beta-end), somatostatin (SRIF) and thyrotropin-releasing hormone (TRH) were tested in a dose equimolar to 30 micrograms of NT for their effects on pupillary diameter (PD) in rabbits. In confirmation of previous findings, NT produced significant miosis. Followed in order of duration of effect were D-Trp11-NT, D-Tyr11-NT, the N-terminal fragment NT1-12, [Gln4] - NT and NMe-NT. The N-terminal fragment NT1-8, D-Arg8-NT, and D-Phe11-NT were weakly active. In addition, the initial N-terminal fragment NT1-6 and the C-terminal fragments NT8-13 and NT9-13 did not affect PD. D-Pro10-NT, beta-end, SRIF, and TRH were totally ineffective. The results of this investigation contribute to support a role for NT on regulation of pupillary function, and suggest that the midportion of NT appears to be critical for the expression of NT-induced miosis.

Animals↗
PubMed1984

Vitreous in lattice degeneration of retina.

A localized pocket of missing vitreous invariably overlies lattice degeneration of the retina. Subjects with lattice also have a higher rate of rhegmatogenous retinal detachment, which is usually a complication of retinal tears. The latter are in turn a result of alterations in the central vitreous--that is, synchysis senilis leading to posterior vitreous detachment. In order to determine if there is either an association or a deleterious interaction between the local and central lesions of the vitreous in eyes with lattice, a comparison was made in autopsy eyes with and without lattice the degree of synchysis and rate of vitreous detachment. Results show no association between the local and central vitreous lesions, indicating that a higher rate of vitreous detachment is not the basis for the higher rate of retinal detachment in eyes with lattice. Also, there was no suggestion of deleterious interaction between the local and central vitreous lesions, either through vitreodonesis as a basis for precocious vitreous detachment, or through a greater degree of synchysis as a basis for interconnection of local and central lacunae (which could extend the localized retinal detachment in eyes with holes in lattice degeneration).

Adult↗
PubMed1983

Orbital inflammation, myositis, and systemic lupus erythematosus.

A 39-year-old man with systemic lupus erythematosus (SLE) experienced three episodes of acute orbital inflammation, a primary feature of each being a markedly enlarged extraocular muscle (myositis). The muscles of the upper trunk were concomitantly inflamed, and full-thickness skin and muscle biopsy specimens demonstrated an inflammatory myositis. The case demonstrates that orbital proptosis and extraocular myositis can be features of SLE.

Adult↗
PubMed1983

Comparison of lesions predisposing to rhegmatogenous retinal detachment by race of subjects.

Because rhegmatogenous retinal detachments are thought to be much less common in blacks than in whites, we compared the incidence of various lesions known to cause or predispose to this condition (synchysis senilis, posterior vitreous detachment, breaks, tears, and holes of the peripheral fundus, and lattice degeneration of the retina) in a series of postmortem eyes on the basis of race. Our statistical analysis also included trauma, myopia, and chorioretinitis. The series included 322 black subjects and 2,012 white subjects. The subjects ranged in age from 20 to 93 years at the time of death. Although the initial data showed a racial difference in the incidence of synchysis senilis of grade 3 (50% destruction) or higher and posterior vitreous detachment (P = .033 and P = .021, respectively), we found no difference when the data were age-corrected.

Adult↗
PubMed1983

Choroidal malignant melanoma in siblings.

Choroidal malignant melanoma was diagnosed on pathologic examination of enucleated globes from a 54-year-old man and his 58-year-old sister. The brother had been monitored at four-month intervals for four years because of a choroidal lesion, which abruptly increased in size, in his left eye. Three years after an examination with normal findings, the sister developed a retinal detachment with a pigmented dome in her right eye. Both patients are doing well five years (Patient 1) and two years (Patient 2) after enucleation. Screening examinations detected two cases of benign melanoma (nevi) in 18 close relatives but this incidence did not exceed chance.

Choroid Neoplasms↗
PubMed1983

Transient retinal striae.

Transient retinal folding was observed in a 28-year-old woman presenting with bilateral uveal inflammation. These retinal striae resolved within 5 weeks as the anterior uveal inflammation responded to topical cycloplegic and corticosteroid therapy. Ultrasonographic findings demonstrated choroidal thickening as a contributing factor in the production of these temporary retinal folds. We present this unusual case since transient retinal folding has been rarely documented, and as far as we are aware, has not been previously investigated by ultrasonography.

Adrenal Cortex Hormones↗
PubMedDate not supplied

Pupillary response to atrial natriuretic factor in rabbits.

This study was designed to evaluate the pupillary and intraocular pressure (IOP) response to exogenously administered atrial natriuretic factor (ANF) in rabbits. Dose-response studies were conducted by administering intracameral (i.c.) ANF (0.1-5 micrograms). The effect of route of administration was evaluated by administering ANF (5 micrograms/kg) intravenous (i.v.) subcutaneous (s.c.) and intraperitoneal (i.p.). In a final study, normal rabbit serum or ANF antiserum were administered i.c. In all studies, pupillary diameter (PD) and IOP were evaluated. Intracameral administration of ANF (0.1-5 micrograms) produced a significant (P less than 0.01) dose-dependent unilateral miosis without affecting IOP. Peripheral (i.v., s.c., i.p.) administration ANF did not affect PD or IOP. Finally, ANF antiserum did not affect PD significantly. These data suggest that ocular, but not circulating ANF may contribute to regulate pupillary function. The mechanism of the miotic response to ANF probably involves interactions with other autonomic neurotransmitters because immunoneutralization of endogenous ocular ANF was without measurable effect.

Animals↗
PubMedDate not supplied

Antagonism of neurotensin induced miosis by thyrotropin-releasing hormone (TRH) in rabbits.

In previous studies we have shown that thyrotropin-releasing hormone (TRH) antagonizes many of the neural effects of neurotensin (NT). This study, evaluated the ability of TRH and two TRH analogs: 3 methyl-His-TRH and Phe2-TRH to affect NT-induced miosis in rabbits. In confirmation of previous findings, NT (30 micrograms) produced a significant miosis. The high (60 micrograms), but not the low (30 micrograms) dose of TRH significantly antagonized NT (30 micrograms)-induced miosis. Of interest was the observation that 3 methyl-His-TRH and Phe2-TRH were more effective than native TRH in blocking NT-induced miosis. The inhibitory effect of 3 methyl-His-TRH on the miotic response to NT exhibited long duration (approximately 60 min) when compared to native TRH and Phe2-TRH. TRH or the TRH congeners had no appreciable effects on pupillary diameter when administered alone. These findings indicate that TRH antagonizes the miotic response to NT, and suggest a hitherto undescribed peptide-peptide interaction involved in regulation of iris motility.

Animals↗
PubMedDate not supplied

Ligneous conjunctivitis: an autosomal recessive disorder.

Two siblings, a boy and a girl, developed a chronic, bilateral conjunctivitis with large recurrent pseudomembranes. The diagnosis of ligneous conjunctivitis was made by excisional biopsies in both. The family was referred for genetic counseling after the second child developed the disorder. On the basis of this family and previous reports, we believe that ligneous conjunctivitis is a genetic disorder inherited in an autosomal recessive pattern and that genetic counseling should be offered to the parents of affected children.

Child, Preschool↗