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Biomedical subjects

B A Barron

Publications and source records attributed to B A Barron.

At least 55 records · Page 3Linked to original sources
PubMed1990

Mooren's ulcer treated with a periosteal graft.

We report a case of recurrent Mooren's ulcer treated with an autogenous periosteal graft. The eye responded well to this therapy. Final visual acuity was 20/40 with spectacle correction of +2.00 + 2.50 X 165.

Aged↗
PubMed1989

Role of sympathoadrenomedullary system in cardiovascular response to stress in rats.

Sympathetic nerve and/or adrenal medulla contributions to stress-induced cardiovascular responses were investigated by factoring out their influence using adrenal demedullation (DMED) and/or chemical sympathectomy with guanethidine (GUAN). Rats divided into 4 groups [sham-operated/saline (SHAM/SAL), SHAM/GUAN, DMED/SAL and DMED/GUAN] were injected i.p. over 4 weeks with either saline or GUAN (25 mg/kg/day). At the end of this treatment period, blood pressure (BP) and heart rate (HR) were monitored via carotid catheter prior to and during restraint in conscious rats. Treatments did not alter basal BP or HR when compared to controls. Restraint increased HR (delta 72 bpm) and systolic, diastolic and mean BP (delta approximately 20 mm Hg) in control animals. Restraint-induced HR change was significantly greater in DMED/SAL animals (delta 88 bpm), but less in SHAM/GUAN animals (delta 40 bpm) than in controls. DMED/GUAN was not different from SHAM/GUAN alone in altering HR response to stress, supporting the greater influence of sympathetic nerves over adrenal medulla in controlling HR. Chronic GUAN abolished normal pressor responses to restraint stress. DMED increased diastolic blood pressure response to stress. However, in DMED/GUAN rats, not only did stress fail to increase blood pressure but rather stress produced hypotension (delta - 34 mm Hg MAP), demonstrating the role of adrenal medulla in maintaining BP during stress. Differential effects of the various treatments on diastolic and systolic pressure suggest that the treatments had effects on peripheral vasculature. These results demonstrate that sympathetic nerves and adrenal medulla have important influences on cardiovascular function during stress and that in the absence of either, the other system may partially compensate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Medulla↗
PubMed1987

Cystoid macular edema following corneal-relaxing incisions.

We believe that this is the first report of cystoid macular edema following corneal-relaxing incisions. Both cases we describe occurred in pseudophakic eyes, one of which contained an ultraviolet light-absorbing intraocular lens. One case was complicated by a corneal perforation and postoperative inflammation. The other case had no apparent intraoperative or postoperative complications other than the cystoid macular edema. In both cases, the cystoid macular edema resolved after the institution of medical treatment, and visual acuity returned to preoperative levels.

Aged↗
PubMed1986

Muscarine binding sites in bovine adrenal medulla.

The presence of muscarinic binding sites in the bovine adrenal medulla was investigated using [3H]QNB and the bovine adrenal medulla. Scatchard analysis combined with computer analysis yielded data consistent with a two binding site configuration. KDs of 0.15 and 14 nM and Bmax s of 29 and 210 fmol/mg protein, respectively, were observed. Displacement of [3H]QNB by various cholinergic agents is, in order of decreasing potency: QNB, dexetimide, atropine, scopolamine, imipramine, desipramine, oxotremorine, pilocarpine, acetylcholine, methacholine and carbachol. These results demonstrate the presence of more than one muscarine binding site in the bovine adrenal gland.

Adrenal Medulla↗
PubMed1986

Modulation of bovine adrenal gland secretion by etorphine and diprenorphine.

Retrograde perfusion was used to investigate the effect of an opiate agonist and an opiate antagonist on the release of catecholamines and [Met5]-enkephalin immunoreactive material (ME-IRM) from bovine adrenal glands. Etorphine (5 X 10(-7) M) inhibited the spontaneous outflow of ME-IRM by approximately 10 percent but had no significant effect on the spontaneous catecholamine release. Acetylcholine (ACh, 5 X 10(-5) M) or 1,1-dimethyl-4-phenylpiperazinium (DMPP, 5 X 10(-5) M) stimulated release of ME-IRM and catecholamines was significantly decreased by the addition of etorphine. Diprenorphine (5 X 10(-7) M) had no significant effect on the spontaneous outflow of either ME-IRM or catecholamines. Diprenorphine reversed the inhibition of the DMPP-stimulated release caused by etorphine. After submaximal stimulation of the gland with DMPP (1 X 10(-5) M), a further stimulation of release of ME-IRM and catecholamines was observed after the addition of diprenorphine alone, i.e., in the absence of etorphine. These results provide further evidence supporting the contention that opiates modulate the secretion of catecholamines and ME-IRM from the adrenal gland.

Acetylcholine↗
PubMed1986

Epikeratophakia with commercially prepared tissue for the correction of aphakia in adults.

The records of all adult patients at Louisiana State University Eye Center, New Orleans, who underwent epikeratophakia for aphakia with commercially prepared tissue since February 1984 were reviewed. The epikeratophakia lenticule was maintained in 37 (92.5%) of 40 patients; complications required the removal of three tissue lenses. The average refractive error three months after surgery was +0.67 +/- 1.97 diopters; 25 (90%) of 28 patients were within 3 D of emmetropia. At six months, the average refractive error was -0.18 +/- 2.27 D. Fourteen (58%) of 24 patients whose visual acuity was 20/40 or better with spectacles before surgery achieved 20/40 spectacle visual acuity three months after surgery, as did ten (59%) of 17 patients at six months and five (83%) of six patients at 12 months. The results in these recent cases are better than in previously reported series and reaffirm the usefulness of epikeratophakia in the treatment of aphakia.

Adult↗
PubMed1986

Muscarinic receptor modulation of release of [Met5]enkephalin immunoreactive material and catecholamines from the bovine adrenal gland.

Muscarinic receptor modulation of secretion from the adrenal medulla was studied using retrogradely perfused bovine tissue. Atropine, at a dose not affecting 1,1 dimethyl-4-phenylpiperizinium (DMPP)-stimulated release, inhibited the acetylcholine (ACh)-stimulated release of noradrenaline and [Met5]enkephalin-immunoreactive material (ME-IRM). DMPP-stimulated release of catecholamines and ME-IRM was potentiated by the addition of methacholine. Pilocarpine significantly potentiated the release of noradrenaline only. Methacholine, pilocarpine or muscarine, when infused alone, had no stimulatory affect on the basal release of ME-IRM. These findings suggest that the muscarinic receptors in the bovine adrenal medulla function by potentiating the release of ME-IRM and catecholamines induced by nicotinic receptor stimulation.

Acetylcholine↗
PubMed1985

Comparison of the effects of Viscoat and Healon on postoperative intraocular pressure.

We compared the effects of Viscoat and Healon on postoperative increases in intraocular pressure in patients undergoing uncomplicated extracapsular cataract extraction with posterior chamber intraocular lens implantation in a prospective, randomized, single-masked study. Eleven eyes received Viscoat and 13 received Healon. The Viscoat or Healon was aspirated from the anterior chamber with the irrigation-aspiration tip of an automated irrigation-aspiration system at the end of the procedure. No prophylactic intraoperative or postoperative ocular hypotensive agents were used. Intraocular pressure was measured at three, six, 12, and 24 hours postoperatively. Compared with preoperative intraocular pressure, postoperative intraocular pressure was significantly increased in both the Viscoat group and the Healon group. Some postoperative intraocular pressures were as high as 50 to 60 mm Hg, despite removal of the viscoelastic substance at the end of surgery. There was no significant difference in the postoperative intraocular pressures of the Viscoat group and the Healon group.

Aged↗
PubMed1985

K-Sol corneal preservation.

K-Sol, a new cornea preserving solution which contains no calf serum of foreign protein and is used for refrigerated storage of donor tissue, has storage procedures identical to those currently used for tissue preservation in McCarey-Kaufman medium. K-Sol can keep corneas alive and usable for penetrating keratoplasty for at least two weeks. The clinical results in a series of 17 patients indicated that tissue preserved in K-Sol for as long as two weeks, even when used by inexperienced surgeons in difficult or unfavorable cases requiring extensive anterior segment reconstruction, including reoperations or retained intraocular lenses, gave results virtually identical to those obtained with tissue preserved in McCarey-Kaufman medium for only two or three days.

Adult↗
PubMed1985

Effects of topical epinephrine on experimental sickle cell hyphema.

Experimental sickle cell hyphemas were produced by injecting human sickle cell-beta(0)-thalassemia blood into rabbit anterior chambers. Eyes treated with topical 2% epinephrine hydrochloride showed no significant difference in the duration of the hyphema or in the percentage of sickled cells in the anterior chamber compared with untreated eyes. Topical 2% epinephrine had no apparent sustained effect on intraocular pressure.

Anemia, Sickle Cell↗
PubMed1984

Release of catecholamines and [Met5]enkephalin immunoreactive material from perfused bovine adrenal glands.

Retrogradely perfused bovine adrenal glands were stimulated by acetylcholine (ACh) and 1,1-dimethyl-4-phenyl-piperazinium (DMPP), with or without hexamethonium. Stimulation by either agent resulted in an increased release of both [Met5]enkephalin immunoreactive material (ME-IRM) and catecholamines as measured by radioimmunoassay and high performance liquid chromatography with electrochemical detection, respectively. ACh (5 X 10(-5) M) and DMPP (5 X 10(-5) M) stimulated the release of norepinephrine greater than the release of epinephrine. The action of these agents was antagonized by hexamethonium (5 X 10(-4) M). DMPP produced the same percentage increase in the release of ME-IRM and norepinephrine but produced a greater percentage increase in the release of ME-IRM compared to the release of epinephrine. There was no apparent correlation between the percentage increase in the release of ME-IRM and either norepinephrine or epinephrine after ACh.

Acetylcholine↗
PubMed1984

Extraction and partial characterization of enkephalin-like peptides from splanchnic nerve.

A method is described for the extraction of enkephalin-like peptides from peripheral nerve using chloroform and acidic methanol to facilitate a differential extraction of peptides and lipid. Porcine splanchnic nerve contains enkephalin-like peptides in low amounts compared to porcine adrenal medulla and striatum. Gel filtration chromatography reveals the presence of enkephalin-like peptides in both processed and cryptic forms. This is the first reported isolation and partial characterization of these peptides in splanchnic nerve. The presence of these peptides in this nerve provides support for the contention that the splanchnic nerve can modulate catecholamine release from the adrenal medulla through an effect on opiate receptors located on chromaffin cells.

Adrenal Medulla↗
PubMed1982

Ultrasonic measurement of the femur length as an index of fetal gestational age.

Fetal femur length was measured with a linear-array, real-time ultrasound scanner in 145 uncomplicated gravid patients from 16 to 42 weeks' gestation. The data were analyzed by means of the method of least-squares linear regression. The results of this analysis generated the following equation: Y = -0.6809 + 0.2127 X (Y = femur length; X = gestational age.) With the use of these data, the error in estimation of gestational age given femur length in the interval 25 to 35 weeks' gestation is less than 5 days. Outside these intervals, there is less precision in this measurement, with a range from 8 days at 15 weeks to 6 days at 40 weeks. Furthermore, the correlation coefficient of gestational age versus fetal femur length is statistically greater than that of the gestational age versus fetal biparietal diameter. These results suggest that the measurement of the fetal femur length is a more precise index of gestational age than is the biparietal diameter. We propose that the ultrasonic measurement of the fetal femur length is a sensitive and precise variable for estimation of fetal growth and development.

Female↗
PubMed1981

Screening strategies for cervical cancer and cervical intraepithelial neoplasia.

Exfoliative cytology is a highly sensitive and inexpensive screening technique for cervical cancer and its precursors. The detection and eradication of the precursors have led to a significant fall in cervical cancer incidence rates and death rates in those areas in which there has been widespread and prolonged use. Recently, however, the utility and cost-effectiveness of cytology has been questioned, and it has been suggested that screening strategies be altered. A consideration of the effect of the transit times of cervical intraepithelial neoplasia on screening intervals and the impact of the changing patterns of cervix cancer epidemiology on screening strategy suggests that a significant change in screening intervals may be counterproductive.

Adult↗