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Andrew Wagner

Publications and source records attributed to Andrew Wagner.

4 recordsLinked to original sources
PubMed2004

New information on the mechanism of forcible ascospore discharge from Ascobolus immersus.

Many ascomycete fungi spurt their spores from asci pressurized by osmosis. This paper explores the details of this process in the coprophilous species Ascobolus immersus, through a combination of biomechanical and biochemical experiments, and mathematical modeling. A. immersus forms large asci that expel 8 spores as a single, mucilage-embedded projectile. Measurements of ascus turgor using a microprobe attached to a strain gauge showed a pressure of 0.3 MPa or 3 atm. Analysis of ascus sap using GC/MS identified glycerol as a major osmolyte, accounting for 0.1 MPa of the osmotic pressure within the ascus sap. A mathematical model indicated that a pressure of 0.2 MPa would be sufficient to propel the cluster of ascospores over the distance measured in previous studies. The difference between the measured and predicted pressures is ascribed to loss of pressure as the spores are forced through the tip of the open ascus.

Ascomycota↗
PubMed2002

Low doses of dizocilpine block the development and subsequent expression of locomotor sensitization to nicotine in rats.

RATIONALE AND OBJECTIVES: We attempted to determine if the effects of the glutamate NMDA receptor blocker dizocilpine (MK-801) on nicotine locomotor sensitization were due to a blockade of the development of sensitization or to state-dependency. METHODS AND RESULTS: In experiment 1, repeated co-administration of a high dose of dizocilpine (0.25 mg/kg) along with 0.4 mg/kg nicotine enhanced locomotion, failed to alter the development of locomotor sensitization to nicotine, but completely blocked the subsequent expression of sensitization to a challenge injection of nicotine alone. However, repeated injections of this dose of dizocilpine alone produced locomotion and sensitization that was equivalent to that produced by the dizocilpine/nicotine combination. In four separate replications in experiments 2 and 3, co-administration of a low dose of dizocilpine (0.075 mg/kg), which did not produce sensitization to itself, blocked both the development of nicotine sensitization and its subsequent expression in response to a challenge injection of nicotine. Moreover, this repeated dizocilpine/nicotine administration did not affect the subsequent development of sensitization to nicotine alone (experiment 3). Suggesting that these effects of dizocilpine may be confined to the development of sensitization, challenge injections of dizocilpine failed to block the capacity to express previously nicotine-sensitized locomotion (experiment 2). CONCLUSIONS: Co-administration of a low dose of dizocilpine can block the development of locomotor sensitization to repeated injections of nicotine without producing state-dependency. Thus, NMDA receptor activation appears to be critical for the development, but not the subsequent expression, of nicotine locomotor sensitization.

Animals↗
PubMedDate not supplied

Refining the laparoscopic retroperitoneal lymph node dissection for testicular cancer.

Since its initial description, the laparoscopic retroperitoneal lymph node dissection has evolved considerably, from a purely diagnostic tool performed to stage germ cell testicular cancer to a therapeutic operation that fully duplicates the open technique. Herein, we describe the current technique employed at our institution, along with illustrations of all surgical steps, and delineate the refinements of the technique over time.

Humans↗