Quantitative in vitro phosphor imaging using [3H] and [18F] radioligands: the effects of chronic desipramine treatment on serotonin 5-HT2 receptors

Traditionally, autoradiography of neuroreceptors is performed in vitro using tritiated ligands and low sensitivity X-ray film, requiring long exposure times. In vivo imaging of neuroreceptors using positron emission tomography (PET) suffers poor spatial resolution, but in vitro PET autoradiography is difficult with film due to the short half-life of the isotopes. Storage phosphor screens provide an extremely sensitive alternative to film. To demonstrate and validate quantitative in vitro phosphor imaging with PET and tritiated ligands, we treated rats chronically with the antidepressant desipramine, which results in decreased binding to serotonin 5-HT(2) receptors. Serotonin 5-HT(2) binding decreased significantly in all cortical regions examined as measured by both [(3)H]ketanserin and [(18)F]setoperone. The data from the two radioligands were not significantly different, and the distribution of the receptors was in agreement with previous reports. We also present data on the reusability of tritium-sensitive phosphor screens, and show that the use of simple corrections allows receptor binding data with PET ligands to be compared across different days. The results indicate that phosphor imaging is a valid, fast, and quantifiable technique for measuring neuroreceptor regulation, and that it provides an excellent tool to corroborate in vivo PET data in vitro at higher resolution.     

Improved yields for the in situ production of [11C]CH4 using a niobium target chamber

The in situ production of [11C]CH4 using a niobium metal target chamber is described. Improved yields are observed in comparison to the previously reported aluminum conical target under similar conditions of beam energy and current. An empirical expression is proposed that quantifies the loss of yield as a function of irradiation time.     

Traumatic lumbar hernia: report of cases and comprehensive review of the literature

BACKGROUND: Acute lumbar hernia secondary to blunt trauma is an uncommon injury of the abdominal wall and, when encountered, is a difficult challenge for the trauma surgeon. METHODS: Three cases of lumbar hernia secondary to blunt trauma are described and a review of the literature was conducted for other such cases. Clinical, anatomic, and demographic data were extracted from these reports and analyzed. RESULTS: Sixty-three cases of lumbar hernia secondary to blunt trauma were found in the English literature and three cases are described here. Hernias occurred most commonly in the inferior lumbar triangle (70%) and were most frequently a result of a motor vehicle collision (71%). Physical examination findings were variable and reported in only a minority of cases (palpable hernia, 33%; flank hematoma, 27%) and associated intra-abdominal injuries were common (61%). Most traumatic lumbar hernias were diagnosed immediately, and computed tomography was 98% sensitive for diagnosis. Fifty-eight percent of patients were managed initially with exploratory laparotomy. Timing of hernia repair was variable. CONCLUSION: Traumatic lumbar hernias are associated with a high incidence of intra-abdominal injury and should be considered in all cases of severe blunt abdominal trauma. Computed tomography should be implemented when the diagnosis is suspected in a hemodynamically stable patient. Repair should be performed by mesh patching techniques at a time based on clinical correlation.     

Antithymocyte globulin is associated with complement deposition in cardiac transplant biopsies

Polyclonal antithymocyte globulin preparations contain antibodies with reactivity to endothelial cells. Therefore, we investigated whether treatment with this reagent caused complement deposition in human cardiac transplants. Frozen tissue was available from endomyocardial biopsies of 75 patients, who were transplanted between April 1995 and April 2000. Nine of these patients were converted from cyclosporin A (CsA) to horse antithymocyte globulin (ATGAM) in the first month after transplantation. All of the biopsies were stained by immunofluorescence for C4d as evidence of activation of the classical pathway of complement. In addition, biopsies from patients treated with ATGAM and control patients were stained for deposition of horse immunoglobulin (Ig)G. All nine patients who received ATGAM had deposition of horse IgG and C4d. Two color stains demonstrated that the horse IgG colocalized with the C4d staining. No staining for horse IgG or C4d was evident in biopsies obtained before ATGAM treatment. Likewise, no staining for horse IgG was detected in seven control patients who had C4d staining. Most patients treated with ATGAM had no histologic evidence of rejection, but did have myocyte damage and macrophage infiltration. Thus prophylactic treatment with ATGAM is associated with the deposition of horse IgG and activation of complement in the transplant.