A tandem-based compact dual-energy gamma generator.

A dual-energy tandem-type gamma generator has been developed at E. O. Lawrence Berkeley National Laboratory and Sandia National Laboratories. The tandem accelerator geometry allows higher energy nuclear reactions to be reached, thereby allowing more flexible generation of MeV-energy gammas for active interrogation applications. Both positively charged ions and atoms of hydrogen are created from negative ions via a gas stripper. In this paper, we show first results of the working tandem-based gamma generator and that a gas stripper can be utilized in a compact source design. Preliminary results of monoenergetic gamma production are shown.

[Influence of prostaglandins on aqueous humour dynamics and intraocular pressure]. / Einfluss der Prostaglandine auf die Dynamik des Kammerwassers und des Augeninnendrucks.

In the glaucoma disease the disturbed trabecular outflow results not only in an increase in the intraocular pressure (IOP) level, but also in an increase in the intraocular pressure fluctuations in the majority of patients. This induces a biomechanical stress that may damage the optic nerve head over time and may result in the typical glaucomatous excavation. Prostaglandin analogues show positive effects on both risk factors. They enhance the uveoscleral outflow of the aqueous humour, improve the trabecular outflow facility and probably the regulatory capacity of the trabecular meshwork itself. This dual mechanism might explain the strong IOP-lowering efficacy of the prostaglandins and their additional property to reduce IOP fluctuations leading to a general improvement of the aqueous humour dynamics. Therefore, it makes sense pharmacologically to combine prostaglandins with those medications that also reduce aqueous humour production.

Anaerobic degradation and transformation of p-toluidine by the sulfate-reducing bacterium Desulfobacula toluolica.

The ability of the strictly anaerobic sulfate-reducing bacterium Desulfobacula toluolica (strain Tol2) to cometabolically degrade p-toluidine (p-methylaniline) while using toluene as the primary source of carbon and energy has been studied. This organism has been shown to modify and degrade toluidine in dense cell suspensions when no other source of carbon and energy is added. The metabolism led to the formation of a variety of metabolites. From these metabolites a biphenyl-like compound as well as phenylacetic acid have been identified by means of HPLC/MS techniques. The probable conversion of p-toluidine to p-aminophenylacetic acid and phenylacetic acid as dead end products suggested that this organism initiates p-toluidine degradation by the carboxylation of the methyl group. If this could be validated in further experiments, it would be the first time that a toluidine was carboxylated at the methyl moiety by an anaerobic, sulfate-reducing bacterium.

Leukemic thyroiditis as the initial relapsing sign in a patient with acute lymphocytic leukemia and blast expression of the neural cell adhesion molecule.

We report a patient with a history of T-cell ALL in remission who presented with symptoms and laboratory values consistent with subacute thyroiditis but was found to have leukemic thyroiditis as the first clinical manifestation of leukemic relapse. Bone marrow examination at this time demonstrated recurrent ALL. After successful re-induction with chemotherapy and an allogeneic bone marrow transplant this patient developed an isolated recurrence of her ALL manifested by symptomatic thyromegaly and a new mediastinal mass that was treated with irradiation. Despite no medullary recurrence of ALL, the patient developed pleuritic chest pain and shortness of breath and succumbed to pericardial extramedullary leukemia 9 months later. This to our knowledge is the third reported case of symptomatic ALL involvement of the thyroid gland and the first to be confirmed histologically. Furthermore, this patient had blast expression of the neural cell adhesion molecule (CD56), a cell surface marker that has not been studied in ALL but has previously been identified as a risk factor for extramedullary leukemia (EML) in acute non-lymphocytic leukemia. The authors hypothesize that CD56 expression in this patient might have contributed to her predisposition to EML.

Fine needle aspiration of thyroid nodules. Determinants of insufficiency rate and malignancy yield at thyroidectomy.

OBJECTIVE: To evaluate patient- and practice-specific determinants of the thyroid nodule fine needle aspiration (FNA) insufficiency rate and malignancy yield at a tertiary-care teaching hospital. STUDY DESIGN: All FNAs of thyroid nodules performed from August 1990 to October 1993 at the Walter Reed Army Medical Center Endocrinology Clinic were reviewed and the results analyzed for correlation with surgical outcome, scintiscanning result and operator experience. Provider-specific factors influencing the FNA insufficiency rate, surgical referral pattern and malignancy yield were evaluated. RESULTS: A total of 504 aspirations in 422 patients with thyroid nodules were included in the analysis. The sensitivity of FNA for detecting malignancy was 80%, specificity was 73.2%, and accuracy was 75.2%. A significant negative correlation was found between recent aspirator experience and the insufficiency rate. Repeat aspiration of nodules previously yielding benign cytology increased the malignancy yield. Surgical excision of nodules with insufficient aspirations gave a low malignancy yield, and aspiration of nodules that were "hot" on scintiscanning rarely yielded false positive FNA results. CONCLUSION: Specific limitations of thyroid nodule FNA include a large number of aspirates containing insufficient cytologic material and a variable malignancy yield. Specific recommendations based on the findings in this report are: the establishment of uniform criteria for judging specimen adequacy, the performance of repeat aspiration on thyroid nodules with previously benign aspirates, the abandonment of scintiscanning in the routine management of thyroid nodules and a conservative approach to clinically indolent nodules repeatedly found to have scant cellularity on FNA. Based on these findings, an algorithm for the diagnostic evaluation of a solid thyroid nodule can be constructed.