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Biomedical subjects

H D Kohn

Publications and source records attributed to H D Kohn.

5 recordsLinked to original sources
PubMed1998

Foveal outer retinal function in eyes with unexplained visual symptoms or acuity loss.

OBJECTIVE: To determine whether foveal outer retinal dysfunction is common in eyes with unexplained visual symptoms or acuity loss. DESIGN: Prospective study. PARTICIPANTS: Seventy-three eyes of 44 consecutive patients with unexplained visual symptoms or acuity loss, 39 eyes of 39 control subjects, and 12 eyes of 7 patients with known maculopathy. INTERVENTION: Foveal cone electroretinography (ERG) and letter recognition perimetry. MAIN OUTCOME MEASURES: Foveal cone ERG data. RESULTS: Abnormal foveal cone ERG data were recorded in 35 (48%) of 73 eyes (23 [52%] of 44 patients). Among these 35 eyes, amplitude was lower than in normal controls (P<.001) and was correlated with visual acuity and the number of letter recognition perimetry errors (P<.05 for both). The latter was higher in eyes with abnormal retinal responses than in symptomatic eyes with normal responses (P<.01). However, initial symptoms, visual acuity, and macular appearance did not differentiate between these 2 groups. Foveal cone ERG test vs retest data showed consistent results. CONCLUSION: Foveal outer retinal dysfunction is a common underlying mechanism of previously unexplained visual symptoms or acuity loss. Foveal cone ERG testing should be considered early in the evaluation of eyes with this presentation.

Adolescent↗
PubMed1998

Foveal dysfunction and central visual field loss in glaucoma.

OBJECTIVE: To determine whether foveal function distal to the ganglion cell layer is an independent predictor of central visual field function in glaucoma. SETTING: University affiliated hospital and private practice. PARTICIPANTS: Twenty-seven eyes (27 patients) with normal-pressure glaucoma, 10 eyes (10 patients) with primary open-angle glaucoma, and 47 eyes of 47 matched normal volunteers. INTERVENTION AND MAIN OUTCOME MEASURES: Foveal cone electroretinogram (ERG) amplitude, relative optic cup to disc area and their relations to Humphrey full-threshold 30-2 visual field central 4-point mean total deviation (C4MTD) and pattern deviation (C4MPD). RESULTS: Foveal cone ERG amplitude was subnormal in 14 (37.8%) of the 37 glaucomatous eyes and lower in the glaucoma group compared with normal eyes (P<.01). The C4MTD and C4MPD were lower in glaucomatous eyes with subnormal amplitudes compared with those with normal amplitudes (P<.01 and P<.05, respectively). Amplitude was directly correlated with C4MTD (P<.01) and C4MPD (P<.01). Relative optic cup to disc area was inversely correlated with C4MTD (P<.001) and C4MPD (P<.001). Partial correlation analysis revealed that amplitude and relative optic cup to disc area were independent predictors of C4MTD and C4MPD. CONCLUSION: Foveal function distal to the ganglion cell layer and optic disc cupping independently predict central visual field function in glaucoma.

Adult↗
PubMed1997

Foveal cone function in nonproliferative diabetic retinopathy and macular edema.

PURPOSE: To study results of foveal cone electroretinography (ERG) in patients with nonproliferative diabetic retinopathy (NPDR), with and without clinically significant macular edema (CSME). METHODS: Electroretinograms of foveal cones were elicited, with a dual-beam stimulator-ophthalmoscope, from 18 consecutive patients with bilateral NPDR and unilateral CSME. RESULTS: Analysis of resulting data revealed that mean amplitude was significantly lower in eyes with CSME and in eyes without CSME., compared with that in normal eyes. Mean implicit time was significantly longer in eyes with CSME compared with that in normal eyes, but in eyes of diabetic patients without CSME., mean implicit time was the same as that in normal eyes. Amplitudes were directly correlated and implicit times were inversely correlated with best-corrected Snellen visual acuity in eyes with and without CSME. Eyes with CSME had significantly lower amplitudes and longer implicit times than their fellow eyes without CSME. In addition, eyes with NPDR, with or without CSME, did not exhibit the normal rise in amplitude with increasing duration of light exposure. CONCLUSIONS: Electroretinographic findings showed abnormalities in foveal cone responses in eyes with NPDR, particularly in the presence of CSME. These results may support a functional role for outer retinal dysfunction in patients with diabetic retinopathy and loss of central vision.

Adult↗
PubMed1996

Rat liver ferritin selectively inhibits expression of alpha-smooth muscle actin in cultured rat lipocytes.

The role of ferritin in lipocyte activation is unknown. This study examined the effect of rat liver ferritin (RLF), human recombinant H-ferritin (HrHF), human recombinant L-ferritin (HrLF), apo-ferritin (apo-RLF), and hemin on lipocyte activation. Lipocytes were cultured on uncoated plastic and were incubated with these agents for 7 days, at concentrations ranging from 10(-14) to 10(-7) M (0.5 to 50 microM for hemin). Collagen/noncollagen protein production and lipocyte proliferation were determined by [3H]proline and [3H]thymidine incorporation, respectively, and the expression of alpha-smooth muscle actin (alpha-SMA) and desmin was determined by Western blot. RLF, at concentrations ranging from 10(-10) to 10(-7) M, decreased alpha-SMA expression by 65-88%. Apo-RLF, HrHF, and HrLF decreased alpha-SMA by 17-45% at 10(-7) and 10(-8) M. Hemin (10 or 50 microM) inhibited alpha-SMA by 37 and 54%, respectively. Desmin expression was not altered by ferritin or hemin. Collagen and noncollagen protein production were not altered by either RLF or apo-RLF. Lipocyte proliferation was decreased by 54, 32, and 40%, by 10(-7) M RLF, HrHF, and HrLF, respectively, whereas apo-RLF had no effect. Thus RLF inhibited lipocyte alpha-SMA expression, which may be due to an effect of sequestered iron, since neither apo-RLF, HrHF, nor HrLF had a potent effect on alpha-SMA expression and all are essentially iron-free. The inhibitory effect of iron-loaded RLF on alpha-SMA expression suggests that tissue ferritin does not initiate lipocyte activation in iron overload, but rather may have a suppressive action on this process.

Actins↗