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Biomedical subjects

G Erickson

Publications and source records attributed to G Erickson.

11 recordsLinked to original sources
PubMed1998

von Willebrand factor does not influence atherogenesis in arteries subjected to altered shear stress.

The role of von Willebrand factor (vWF) in arterial neointimal formation that develops in arteries with altered shear stress was investigated using normal, heterozygous, and homozygous von Willebrand disease pigs (ie, vWD, or lacking vWF) that were fed normal pig chow. Shear stress was applied to carotid and femoral arteries with a Goldblatt clamp for 14 days, producing a > or = 80% stenosis. Neointimal lesion size was measured by computer-assisted morphometry. Expression of proliferative cell nuclear antigen (PCNA) by neointimial and medial cells was used as a relative index of proliferative activity. For shear-stressed arteries, there was no significant difference in the number of smooth muscle cell layers in the lesion, lesion size, and percent of PCNA-positive neointimal or medial cells among normal, heterozygous, and homozygous vWD pigs (P> or =.1, ANOVA). Lesions in pigs that expressed vWF (normals and heterozygotes) contained large amounts of vWF in the neointima, whereas lesions in vWD pigs had no detectable vWF. Moreover, no foam cells were detected in the lesions. Thus, the absence of vWF apparently does not alter the size of lesions in shear-stressed arteries in vWD pigs or the number of neointimal or medial cells expressing PCNA. Mechanism(s) involved with shear-induced modulation of smooth muscle cell proliferation, then, can operate independently of vWF in normolipemic pigs.

Animals↗
PubMed1996

Go for it!

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Career Mobility↗
PubMed1996

Operating safely.

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Ambulatory Surgical Procedures↗
PubMed1995

Gonadotropin-releasing hormone overcomes follicle-stimulating hormone's inhibition of insulin-like growth factor-5 synthesis and promotion of its degradation in rat granulosa cells.

The effect of a gonadotropin-releasing hormone-agonist (GnRH-a) on the synthesis of insulin-like growth factor-binding protein-5 (IGFBP-5), a physiological marker for atresia, was investigated. Granulosa cells obtained from diethylstilbestrol (DES)-treated immature female rats were cultured in serum-free medium for 72 h with GnRH-a and the conditioned media were subjected to immunoblot analysis using rat IGFBP-5 specific antibody. GnRH-a caused a dose-dependent (ED50 = 8.6 x 10(-11) M) accumulation of IGFBP-5, which migrated as 35 (non-glycosylated) and 36 kDa (glycosylated) bands under reducing conditions. A maximally effective dose of GnRH-a (10(-9) M) caused a 4-fold increase in IGFBP-5 accumulation. In contrast, increasing doses of porcine follicle-stimulating hormone (pFSH) caused a biphasic effect on IGFBP-5 accumulation. A low dose of pFSH (0.25 ng/ml) increased and higher doses of pFSH (22.5 ng/ml) decreased the 35 and 36 kDa IGFBP-5 bands. In the presence of high doses of pFSH (20.75 ng/ml), a 22 kDa band corresponding to a cleaved IGFBP-5 fragment appeared in the media. When the granulosa cells were cultured with a saturating dose of pFSH, co-addition of GnRH-a dose dependently inhibited the FSH effects (ED50 = (2.3-3.7) x 10(-10) M). The GnRH-a effects were completely blocked by co-incubation with GnRH-antagonist. IGFBP-5 mRNA accumulation levels were increased by GnRH-a in a dose dependent manner.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

The chronic intracerebroventricular infusion of interleukin-1 beta alters the activity of the hypothalamic-pituitary-gonadal axis of cycling rats. II. Induction of pseudopregnant-like corpora lutea.

The acute administration of interleukin-1 beta (IL-1 beta) into the brain ventricles of rats has been shown to cause a significant decrease in plasma LH levels, a phenomenon primarily mediated through inhibition of LHRH release. However, there are no studies of the long-term consequences of IL-1 beta injected intracerebroventricularly on the hypothalamic-pituitary-gonadal axis. In particular, we became interested in determining whether IL-1 beta exerts deleterious effects on reproductive parameters, and to what extent they might be caused by a lowering of circulating gonadotropins. In the present experiments, we therefore investigated the effects of the infusion of IL-1 beta to intact cycling female rats and compared them to those observed in rats injected with a potent LHRH antagonist. Although blockade of LHRH receptors caused a modest and delayed inhibition of progesterone secretion, infusion of IL-1 beta (4 ng/h for 4-6 days) was accompanied by persistent and significant increases in plasma P4 levels. In these rats, the PRL release was erratic, with low values during the morning and generally extremely elevated values during the night. The volume of the corpora lutea-I (CL-I) of rats exposed to IL-1 beta, but not to the vehicle or the LHRH antagonist, was significantly increased, and the lutein cells showed extensive hypertrophy. These results indicate that prolonged infusion of IL-1 beta into the brain of cycling rats blocks luteolysis in newly formed CL. These changes were not present in rats injected with the LHRH antagonist, suggesting that they were not primarily related to decreases in gonadotropin secretion. We propose that the high plasma PRL levels may play a role in the changes in ovarian activity which we observed, through other mechanisms, such as sustained increases in adrenal epinephrine and/or glucocorticoids, may also be involved. These findings indicate a novel role for central IL-1 beta in the prevention of luteolysis and the transformation of the CL of the cycle into a CL of pseudopregnancy.

Animals↗
PubMed1983

Histopathologic and ultrastructural analysis of congenital corneal staphyloma.

Although the visual prognosis for eyes with congenital corneal staphyloma has been considered hopeless, we successfully treated a 1-month-old girl with this condition. We performed two penetrating keratoplasties, operating on the left eye first and then, one week later, on the right eye. During each procedure, we totally resected the staphyloma and excised the iris which was adherent to the posterior surface of the cornea. We then sutured an 11-mm corneal button into place with 34 interrupted 10-0 nylon sutures. Light and transmission electron microscopy of the Descemet's membrane and endothelium. The left eye had two rejection episodes and underwent a second penetrating keratoplasty. The graft in this eye is now opaque. The child follows objects well with her right eye.

Cornea↗
PubMed1979

Below-knee orthosis: a wrap-around design for ankle-foot control.

Control of foot and ankle positions with orthotic appliances is generally more difficult to accomplish in children with spastic than flaccid paralytic disorders. Our new design for a custom molded plastic ankle-foot orthosis has proven superior to other designs in most applications. The appliance is vacuum molded from very thin polypropylene plastic and innerfaced with a foam material (Aliplast). The limb is enclosed completely in plastic with an anterior opening secured by several Velcro straps. Although the material is soft and pliable, the circumferential support provides remarkably rigid control of the limb. The orthosis has been successfully applied to children with polio, meningomyelocele and all forms of spastic and athetoid cerebral palsy. In addition to superior limb control, another advantage appears to be reflex inhibition of abnormal motor tone in may spastic patients. Patients have preferred this orthosis to those previously worn probably due to greater comfort. The limitation of adjustability of dorsiflexion can be compensated by heel or sole shoe lifts. Excessive heat created by the "wrap-around" design can be reduced by a thin cotton sock extended above the orthosis.

Adult↗
PubMed1978

Action of PMSG and asialo-PMSG on rat Leydig and granulosa cells.

Highly purified pregnant mares serum gonadotropin (PMSG) was nearly as potent as ovine luteinizing hormone (LH) and human follicle stimulating hormone (hFSH) when bioassayed in vitro in systems known to respond primarily to LH or FSH. An analogue of human chorionic gonadotropin treated with neuraminidase, galactosidase, beta-N-acetylglucosaminidase, and mannosidase (hCG) inhibited the stimulatory effects of hCG, LH, and PMGS on cAMP accumulation in rat Leydig cells but did not inhibit the stimulatory effects of FSH or PMSG on cAMP accumulation in ovarian granulosa cells obtained from immature rats fed diethylstillbestrol. Thus PMSG appeared to form functional complexes with both LH and FSH receptors and may be unique among mammalian gonadotropins. Treatment of PMGS with neuraminidase increased its potency nearly tenfold in vitro apparently by increasing its affinity for both LH and FSH receptors. Although the kinetics of PMSG binding were not investigated with radiolabeled materials, indirect functional binding studies are described that suggest that hCG more rapidly forms stable hormone-receptor complexes than PMSG, asialo-PMSG, FSH, and LH when all hormones are incubated under the same conditions.

Animals↗