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Biomedical subjects

R Austin

Publications and source records attributed to R Austin.

12 recordsLinked to original sources
PubMed1992

Effects of prolactin on secretion and synthesis of human chorionic gonadotropin in human term placentas in vitro: short-term increase in secretion, followed by medium-term suppression of synthesis and secretion.

We studied the influence of human prolactin on the secretion and de novo synthesis of human chorionic gonadotropin (hCG) in the human term placenta in culture. Placental tissue from 14 patients with uncomplicated pregnancies and deliveries was prepared mechanically, with addition of a Percoll gradient step. hCG levels were determined in the culture media and in the cytosolic fraction of cells by means of an enzyme immunoassay with coated beads. The amount of newly synthesized hCG was measured by the extent of incorporation of 35S-methionine into the hCG molecule. Our results showed that human prolactin had two different effects in vitro: between 1/2 and 1 h, prolactin slightly increased secretion of hCG into the culture medium without affecting de novo synthesis; after 2 h, prolactin began to cause a significant decrease in both secretion and de novo synthesis of hCG over several hours. It appears that both effects are receptor mediated, for ovine prolactin failed to produce any response. We conclude that prolactin is one of the main factors regulating the synthesis and secretion of hCG in the human trophoblast at term.

Animals↗
PubMed1991

Pulmonary changes in congenital syphilis.

Three of seven infants afflicted with congenital syphilis at our institution in the past five years showed diffuse pulmonary infiltrates. These persisted long after adequate antibiotic treatment of the primary infection. Review of pathologic literature suggests these infiltrates represent pulmonary immaturity, extramedullary hematopoiesis, and interstitial scarring.

Humans↗
PubMed1976

Tardy palsy of the radial nerve from a Monteggia fracture.

A case of tardy palsy of the radial nerve, which developed 65 years after a Monteggia fracture that remained unreduced, is described. The weakness recovered sufficiently well for a tendon transference to bu unnecessary, partly because the patient was semi-retired. This condition is rare but comparison with the only two similar reported case of tardy radial and posterior interosseous nerve palsy associated with long-standing dislocation of the superior radio-ulnar joint suggests that the prognosis for recovery of such a palsy following excision of the radial head is better than might be expected.

Aged↗
PubMedDate not supplied

Steroid hormone modulation of cAMP production in response to beta adrenergic receptor stimulation in genital tract myocytes.

beta-Adrenergic receptor stimulation results in smooth muscle relaxation through activation of adenylyl cyclase and subsequent cyclic AMP (cAMP) production. The present study was performed to evaluate the effects of steroid hormones (i.e. testosterone and hydrocortisone) on beta 2-adrenergic receptors and their signal transduction in the DDT1 MF-2 genital tract myocyte. Radioligand binding studies demonstrated that these two steroid hormones produced a 70 to 80% increase in the density of beta 2-adrenergic receptors in these myocytes. Stimulation of the beta 2-adrenergic receptors with isoproterenol resulted in a significant increase of cAMP in control myocytes; cells treated with testosterone for 24 h demonstrated a comparable response to isoproterenol, whereas hydrocortisone for 24 h resulted in a 50% greater cAMP response. In contrast to the response at 24 h, stimulation of myocytes after testosterone treatment for 48 h resulted in a cAMP response comparable to that seen in response to hydrocortisone at 24 h. Studies performed using theophylline demonstrated similar cAMP responses at 24 h between the control and testosterone-treated myocytes, thereby ruling out the possibility that the delayed increase of the cAMP response after testosterone was caused by stimulation of phosphodiesterase. Direct stimulation with forskolin resulted in greater cAMP production in the testosterone-treated myocytes compared to controls, thereby refuting the possibility that testosterone directly suppresses adenylyl cyclase activity at 24 h. These findings suggest that although both testosterone and hydrocortisone produce a twofold increase in beta 2-adrenergic receptor density in the DDT1 myocytes, beta 2-adrenergic receptors expressed in response to hydrocortisone appear functional at 24 h resulting in increased cAMP production, whereas those expressed in response to testosterone require 48 h to demonstrate increased functional activity.

Animals↗