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F Labella

Publications and source records attributed to F Labella.

4 recordsLinked to original sources
PubMed1993

An image analyzer study of central serous chorioretinopathy.

The angiographic characteristics of central serous chorioretinopathy (CSC) were studied by analyzing digitalized angiograms with an IMAGEnet system. We determined the type of leak, its location, and its distance from the fovea and from the center of the detachment. Round leaks were located farther from the detachment center and farther from the fovea than smokestack leaks. Detachments tended to center on the fovea regardless of the leak to fovea distance. These findings suggest that for serous detachment of the sensory retina to develop and be maintained, there must be a diffuse dysfunctional area of retinal pigment epithelium and a focal leak.

Adult↗
PubMed1984

Endogenous digitalis-like factors: in vitro comparison of biological and immunological activities of peptide and steroid candidates.

Endogenous substances that modulate the activity of (Na+ + K+)-ATPase through interaction at the cardiac glycoside site have been postulated. Reports of digitalis-like biological and immunological activity exhibited by certain ACTH/MSH peptides and 14-OH steroids make these compounds potential candidates as endogenous digitalis-like factors. We tested several ACTH/MSH peptides and 14 alpha-OH steroids in four in vitro assays and detected no significant cardiac glycoside-like activity. On the other hand, chlormadinone acetate, a progesterone derivative shown to bind with high affinity to the digitalis receptor, was nearly equipotent to digoxigenin in a [3H]ouabain radioreceptor assay. In a [3H]digoxin radioimmunoassay, however, digoxigenin and digoxin were equipotent but chlormadinone acetate was inactive. A clear dissociation between radioreceptor assay and radioimmunoassay activity was also observed using 15 beta-OH-progesterone. Our findings indicate that (a) ACTH/MSH peptides and 14 alpha-OH steroids are not viable candidates as endogenous digitalis-like factors, (b) digoxin antibodies are not necessarily directed at molecular determinants critical for biological activity, and (c) among the compounds reported to exhibit digitalis-like activity and postulated to share structural features with an endogenous steroidal digitalis-like factor, only chlormadinone acetate and its congeners appear to constitute tenable models.

Adrenocorticotropic Hormone↗
PubMed1975

Anterior pituitary hormone release in vitro inversely related to extracellular osmolarity.

Release of hormones from bovine anterior pituitary tissue in vitro was inveresly related to the osmolarity of the incubation medium. Addition of each of several ionic or non-ionic solutes to Krebs-Ringer-bicarbonate (KRB) or to beef serum inhibited hormone release. If the value of 286 mOsm/liter of KRB is considered as 100%, the osmolarity of the medium was altered from -15% to +10% of control. Over this range, an increase in osmolarity of 10% resulted in the following percentage inhibition: ACTH, 47; PRL, 43; TSH, 36; LH, 23; GH, 18; maximal percentage inhibition over this range was as follows: ACTH, 80; PRL, 60; TSH, 60; LH, 45; GH, 40. The inverse relationship between extracellular oxmolarity and secretion of ACTH and PRL would appear to be appropriate in view of the salt and water retaining actions of these hormones. The sensitivity of the response to osmotic changes suggests a possible role of body osmolarity in the regulation of adenohypophysial secretion.

Adrenocorticotropic Hormone↗