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J A Sampson

Publications and source records attributed to J A Sampson.

6 recordsLinked to original sources
PubMed2006

Abundance and ultrastructural diversity of neuronal gap junctions in the OFF and ON sublaminae of the inner plexiform layer of rat and mouse retina.

Neuronal gap junctions are abundant in both outer and inner plexiform layers of the mammalian retina. In the inner plexiform layer (IPL), ultrastructurally-identified gap junctions were reported primarily in the functionally-defined and anatomically-distinct ON sublamina, with few reported in the OFF sublamina. We used freeze-fracture replica immunogold labeling and confocal microscopy to quantitatively analyze the morphologies and distributions of neuronal gap junctions in the IPL of adult rat and mouse retina. Under "baseline" conditions (photopic illumination/general anesthesia), 649 neuronal gap junctions immunogold-labeled for connexin36 were identified in rat IPL, of which 375 were photomapped to OFF vs. ON sublaminae. In contrast to previous reports, the volume-density of gap junctions was equally abundant in both sublaminae. Five distinctive morphologies of gap junctions were identified: conventional crystalline and non-crystalline "plaques" (71% and 3%), plus unusual "string" (14%), "ribbon" (7%) and "reticular" (2%) forms. Plaque and reticular gap junctions were distributed throughout the IPL. However, string and ribbon gap junctions were restricted to the OFF sublamina, where they represented 48% of gap junctions in that layer. In string and ribbon junctions, curvilinear strands of connexons were dispersed over 5 to 20 times the area of conventional plaques having equal numbers of connexons. To define morphologies of gap junctions under different light-adaptation conditions, we examined an additional 1150 gap junctions from rats and mice prepared after 30 min of photopic, mesopic and scotopic illumination, with and without general anesthesia. Under these conditions, string and ribbon gap junctions remained abundant in the OFF sublamina and absent in the ON sublamina. Abundant gap junctions in the OFF sublamina of these two rodents with rod-dominant retinas revealed previously-undescribed but extensive pathways for inter-neuronal communication; and the wide dispersion of connexons in string and ribbon gap junctions suggests unique structural features of gap junctional coupling in the OFF vs. ON sublamina.

Animals↗
PubMed1997

Management of an uncomplicated posterior elbow dislocation.

OBJECTIVE: To present a case of an uncomplicated posterior elbow dislocation in a US World Cup athlete and discuss her rehabilitation. BACKGROUND: Traditional protocol for management of this injury has been splint immobilization for several weeks, but research suggests a shortened duration of immobilization and early active motion. DIFFERENTIAL DIAGNOSIS: Elbow dislocation with possible fracture. TREATMENT: The dislocation was reduced and a compression bandage and sling were applied. The sports medicine staff and athlete determined that rehabilitation would involve limited immobilization with a posterior splint. Also, active range-of- motion exercises were to be incorporated early in the range-of- motion program to decrease pain at the articulation. UNIQUENESS: The athlete was not immobilized and her aggressive five-phase rehabilitation program progressed according to decrease in inflammation and increase in range of motion and strength. CONCLUSIONS: Shortened immobilization and return to World Championship competition 6 weeks postinjury had no longterm adverse effects on the athlete.

Journal Article↗
PubMed1987

Clinical aspects of infection with Yersinia enterocolitica in adults.

Yersinia enterocolitica was isolated from the feces of 29 patients over a three-year period following the introduction of a selective culture medium. Y. enterocolitica was the third most common enteric pathogen after Campylobacter jejuni and Salmonella in this series of 3795 specimens from a predominantly adult population. The isolation rate of Y. enterocolitica was 0.9% and this represented 15.8% of positive cultures. The usual symptoms of Yersinia infection were diarrhea (93%) and abdominal pain (72%), often associated with tenderness in the right iliac fossa and fever. Fourteen patients required admission to hospital and four came to surgery for possible appendicitis. Acute terminal ileitis and mesenteric lymphadenitis were noted in each case. Two patients who were HLA-B27 positive had a reactive arthritis as their dominant complaint. In conclusion, Y. enterocolitica has emerged as a common cause of diarrhea in adults. It is an important cause of symptoms resembling those of acute appendicitis and is occasionally complicated by reactive arthritis.

Adolescent↗