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Biomedical subjects

T B Connor

Publications and source records attributed to T B Connor.

At least 19 recordsLinked to original sources
PubMed1994

Surgical removal of an extrafoveal fibrotic choroidal neovascular membrane with foveal serous detachment in age-related macular degeneration.

BACKGROUND: Visual recovery after submacular surgery for age-related macular degeneration (AMD) has been very limited. METHODS: A patient with an extrafoveal fibrotic choroidal neovascular membrane from AMD had an overlying serous foveal detachment with the fibrotic tissue elevating the foveal retina. Photocoagulation of the neovascular membrane was not recommended because of its nonpigmented, fibrotic nature. The membrane was surgically excised. RESULTS: Preoperative and postoperative visual acuity and central 30 degrees visual fields were followed. Visual acuity improved from 20/200 to 20/25, and a preoperative central scotoma resolved completely 18 months after surgical excision of the extrafoveal fibrotic neovascular membrane. There were no intraoperative or postoperative complications. CONCLUSION: This type of patient may represent a distinct subset of patients with AMD amenable to subretinal surgery who could potentially have good recovery of vision.

Aged↗
PubMed1990

Systemic amiloride inhibits experimentally induced neovascularization.

Amiloride is an inhibitor of urokinase-type plasminogen activator, and might therefore have an inhibitory effect on neovascularization. Neovascularization was induced in rabbit corneas via local implantation of prostaglandin E1 pellets prepared in a slow-release polymer. Animals received daily intraperitoneal injections of 30 mg of amiloride, or an equivalent volume of saline solution for 5 days; both were well tolerated without severe untoward effect. Neovascular response, as documented by corneal photographs, was evaluated after 5 days of injections. The area of induced corneal neovascularization was decreased by 55% in animals receiving amiloride when compared with controls. Thus, amiloride and similar compounds may prove useful in the study and management of neovascularization.

Alprostadil↗
PubMed1989

Transforming growth factor beta. A biologic chorioretinal glue.

Transforming growth factor beta (TGF-beta) stimulates fibrosis. We studied its possible role as a bioactive substance for inducing localized chorioretinal wound healing along the edge of a retinal tear. The TGF-beta was applied to induced retinal tears that were examined histopathologically. One day after surgery, neither control nor TGF-beta-treated eyes developed chorioretinal wound healing. Four days, two weeks, and two months after surgery, the control eyes still had not developed chorioretinal wound healing. In contrast, the edges of the retinal tear treated with TGF-beta were adherent to the underlying Bruch's membrane via localized fibrous tissue without apparent effects elsewhere. These results demonstrate intraocular in vivo bioactivity of TGF-beta and suggest that TGF-beta may have a potential role as an alternative means for inducing a chorioretinal adhesion in the treatment of retinal tears.

Animals↗
PubMed1989

Correlation of fibrosis and transforming growth factor-beta type 2 levels in the eye.

Approximately 1 out of every 10 eyes undergoing surgery for retinal detachment develops excessive intraocular fibrosis that can lead to traction retinal detachment and ultimate blindness. This disease process has been termed proliferative vitreoretinopathy (PVR). The ability to monitor and grade this fibrotic response accurately within the eye as well as the ability to aspirate vitreous cavity fluid bathing the fibrotic tissue makes this an ideal setting in which to investigate the development of fibrosis. Although laboratory studies have recently shown that transforming growth factor-beta (TGF-beta) can enhance fibrosis, little clinical evidence is yet available correlating the level of this or other growth factors with the degree of fibrosis in a clinical setting. We have found that vitreous aspirates from eyes with intraocular fibrosis associated with PVR have more than three times the amount of TGF-beta (1,200 +/- 300 pM [SEM]) found in eyes with uncomplicated retinal detachments without intraocular fibrosis (360 +/- 91 pM [SEM]). Using an in vitro assay, 84-100% of the TGF-beta activity could be blocked with specific antibodies against TGF-beta 2, whereas only 10-21% could be blocked by specific antibodies against TGF-beta 1. TGF-beta 1 was used in an animal model of traction retinal detachment. Since beta 1 and beta 2 have essentially identical biologic effects and only human beta 1 was available in quantities required, beta 1 was chosen for these in vivo studies. The injection of TGF-beta1 plus fibronectin (FN) but not TGF-beta1 alone into the vitreous cavity of rabbits resulted in the increased formation of intraocular fibrosis and traction retinal detachments as compared to control eyes. In previous studies, intravitreal FN levels were also found to be elevated in eyes with intraocular fibrosis.

Adolescent↗
PubMed1984

Circulating thyroid hormone changes in acute trauma: prognostic implications for clinical outcome.

Alterations in circulating thyroid hormone concentrations occur in a variety of nonthyroidal disease states. In the present study, thyroid hormone levels were measured every 8 to 12 hours in 19 otherwise healthy individuals suffering acute severe trauma necessitating admission to the Maryland Institute for Emergency Medical Services Systems. Four fatalities occurred within 48 hours of admission. The mean total T3 level fell rapidly after the onset of trauma and remained low throughout the observation period. Reverse T3 rose concurrent with the fall in T3 but gradually returned to normal in the survivors. Total and free T4 levels remained normal in the survivors but fell below normal in the fatalities on the samples obtained preceding death. Changes in free T4 were consistent in three separate radioimmunoassay systems. Pharmacologic doses of glucocorticoids administered to seven of the 15 survivors and to the four fatalities did not result in an acute depression in total and free T4 levels in the survivors. Post-mortem examination of three fatalities did not reveal evidence of significant thyroid or pituitary disease. These results suggest that in acutely traumatized patients: 1) T3 declines rapidly and remains depressed throughout the illness; 2) continued fall of T4 to subnormal levels is associated with a poor prognosis; and 3) steroid therapy alone cannot explain the acute changes observed in hormone levels.

Acute Disease↗
PubMed1983

Ectopic pro-opiolipomelanocortin: sequence of cDNA coding for beta-melanocyte-stimulating hormone and beta-endorphin.

A recombinant bacterial plasmid, pMS1, was constructed that contains 318 nucleotides complementary to a portion of pro-opiolipomelanocortin (proOLMC) messenger RNA from an ectopic adrenocorticotropin-producing tumor. The cloned complementary DNA insert, which contains the sequence that codes for all of the beta-melanocyte-stimulating hormone and beta-endorphin portions of proOLMC, as well as the 3' nontranslated section, is identical to the genomic sequence. Hybridization of tumor proOLMC complementary DNA to RNA subjected to electrophoresis and transferred to a nitrocellulose filter revealed two proOLMC messenger RNA species in the tumor polyadenylated RNA, but only one in pituitary polyadenylated RNA. At least one of the tumor proOLMC messenger RNA's is similar, if not identical, to human pituitary proOLMC messenger RNA.

Amino Acid Sequence↗
PubMed1983

Degradation of basement membrane components by vascular endothelial cells: role in neovascularization.

A retina-derived substance (or substances) has been identified that stimulates vascular endothelial cells to degrade three structural components of basement membrane: type IV collagen, fibronectin and laminin. In basement membrane surrounding existing blood vessels, endothelial cells stimulated in this way can presumably migrate through the resulting gaps and form new vascular sprouts. These events may therefore represent the earliest steps in the formation of new blood vessels.

Animals↗
PubMed1981

Computed tomography for localization of parathyroid adenomas.

Fourteen consecutive patients with the clinical diagnosis of primary hyperparathyroidism had computed tomography (CT) preoperatively to evaluate the use of CT in localizing parathyroid adenomas. The patients were scanned from above the level of the thyroid cartilage to the bifurcation of the trachea. Computed tomography correctly identified, prospectively, the site of the adenoma in 7 of 14 patients, including one adenoma that was ectopic in location. Nine of these patients also had barium esophagrams, and this study was accurate in only three of the nine. Our study suggests that CT may be beneficial in the preoperative localization of parathyroid adenomas, particularly those in ectopic locations.

Adenoma↗
PubMed1979

Effect of androgen on growth hormone secretion and growth in boys with short stature.

The response of plasma growth hormone (GH) to insulin-induced hypoglycaemia (IIH) and arginine infusion (AI) was studied in 22 young males (ages 8 to 17 years) with short atature and absent or delayed sexual maturation, before and after androgen administration. During initial evaluation, 5 patients had blunted GH response to IIH, 12 responded subnormally to AI and 4 failed to respond normally to either stimulus. These same studies were repeated in each patient following androgen administration. The source of androgen was as follows: a) 5 days of testosterone propionate (25 mg intramuscularly daily) in 20 patients. b) Methyltestosterone, 10 mg t.i.d. orally for four days in the other 2 subjects. In almost every case, androgen administration resulted in raising the levels of fasting GH and enhancement of the GH responses to IIH and AI was observed. Patients manifesting subnormal GH responses to these stimuli before androgen consistently demonstrated a normal response when challenged with identical stimuli during androgen administration. Growth velocities during the year following these studies were significantly increased in most instances and the growth spurts correlated well with the progression of sexual maturation. Sustained improvement in the GH responses to IIH and AI were uniformly observed in 3 patients when repetitive studies were performed 8 to 12 months later during spontaneous advancing sexual development. The results indicate that brief androgen administration can be helpful in delineating the cause of growth retardation in boys with short stature and delayed sexual maturation, particularly when the diagnosis of isolated growth hormone deficiency is suspected. They also offer prognostic value in determining growth potential in this same group of young males.

Administration, Oral↗