Carbon-11 labelled tyrosine to study tumor metabolism by positron emission tomography (PET)

To measure the rate of protein synthesis in human neoplasms by positron emission tomography, we prepared no carrier added DL-(1-¹¹C)-tyrosine by ¹¹C-carboxylation of the appropriate -lithioisocyanide followed by hydrolysis of the isocyanide function and removal of the protecting methoxy group. The purification, resolution and solvent switch to saline was performed by high performance liquid chromatography (HPLC). DL-(1-¹¹C)-Tyrosine in 0.1 N NaH₂PO₄ buffer was prepared with a radiochemical yield of 8%–16% (EOS, 35 min). The enantiomeric separation and solvent switch to saline were achieved in 5 min and 10 min respectively. Consequently L-(1-¹¹C)-tyrosine in physiological saline was obtained in 2%–4% radiochemical yield. Tumor accumulation in rats with the experimental WALKER 256 carcinosarcoma was observed for both the L- and D-isomer. Using positron emission tomography a tumor/muscle ratio of two was observed for the L-isomer 15 min after injection. The corresponding figure for the D-isomer was 2.5. The first clinical results with DL-(1-¹¹C)-tyrosine show accumulation of radioactivity in meningioma, a primary breast carcinoma and in liver metastases of a colonic carcinoma.     

A study on impact and tensile strength of acrylic resin filled with short ultra-high molecular weight polyethylene fibers

In dentistry, acrylates have been used for preparing denture bases for 50 years. Although polymethylmethacrylates (PMMA) are known to be an ideal base material, they possess some undesirable mechanical properties, especially their impact strength and tensile strength, which appear to be unsatisfactory for some applications. Additives and fibers have therefore been used to enhance and improve these properties over the last two decades. The present article describes the mechanical properties, impact and tensile strength of PMMA reinforced with chopped ultra-high molecular weight polyethylene fiber (6 mm long). It was found that, although the processing involved for high loading of fibers into the PMMA was difficult, the resulting improvement of impact strength was substantial.     

Granulocyte colony-stimulating factor in neutropenic, pediatric solid tumor patients following chemotherapy

Granulocyte colony-stimulating factor (G-CSF) has been used to reduce the duration and/or degree of neutropenia of different etiologies in recent years. In this study, experience with the use of G-CSF (Neupogen, Roche) after 123 courses of highly myelosuppressive chemotherapy administered to 31 (20 female, 11 male) patients with pediatric solid tumors is reported. G-CSF was initialed at a white blood cell (WBC) count of 918 ± 452/μL (100-2000), at a dose of 7.6 ± 2.3 μg/kgl/d (5-14) subcutaneously for 5.2 ± 2.4 days (2-18). G-CSF was given for afebrile neutropenia after 82 and for febrile neutropenia after 41 courses. Only in two episodes where G-CSF was given for afebrile neutropenia, fever developed. The average hospitalization period for febrile neutropenia was 9.8 ± 3.3 days (5-20). Chemotherapy could be given on scheduled time and dosage in 90% of the courses in which G-CSF was used for afebrile neutropenia. G-CSF was well tolerated. Bone pain was observed in two patients and urticaria in one patient. In conclusion, G-CSF increased the WBC count effectively, there were only two febrile episodes in 82 courses in children receiving G-CSF for afebrile neutropenia, it was well tolerated, and it was found to be feasible for use in a developing country.     

X-Ray Structure and Crystal Lattice Interactions of the Taxol Side-Chain Methyl Ester

A colorless, parallelepiped crystal of methyl (2R,3S)-N-benzoyl-3-phenylisoserinate belonging to the space group P2_l with a = 5.414(4), b = 7.813(1), c = 17.802(7) , = 90.87(4)°, Z = 2, V = 752.9 ³, D _calc = 1.32 g cm^–3, and µ_calc = 1.02 cm^–1 was selected and the structure solved using direct methods. Refinement led to a final R = 0.079 for 819 [F _o 5(F_o)] reflections. Intermolecular hydrogen-bonding interactions are prevalent in the crystal lattice of this compound.     

Cerebral atrophy in Cushing's disease

BACKGROUND: Cushing's disease causes significant pathological changes throughout the body as a result of elevated cortisol levels. Very few systematic investigations have focused on the morphologic effects of hypercortisolism on the central nervous system. The validity of using premature cerebral atrophy as a diagnostic tool for Cushing's disease remains unknown. METHODS: This study includes 63 patients with Cushing's disease who were evaluated and treated at the University of Virginia Medical Center. Radiologists randomly compared these individuals with age- and sex-matched controls in a blinded protocol, assessing the degree of cerebral atrophy on computed tomography and magnetic resonance scans. RESULTS: Patients with Cushing's disease showed significant premature atrophy when compared with controls. This trend continued after subdividing the groups based on age and duration of symptoms except in the following groups: age greater than 60, duration of symptoms less than 1 year, and symptoms lasting between 4-5 years. CONCLUSIONS: Excluding the three aforementioned groups, the hypercortisolemic state manifested in patients with Cushing's disease promotes the premature development of cerebral atrophy, which can be identified on routine radiologic imaging and may assist in the clinical diagnosis of the condition.     

Sigmoidoscopy in minor lower gastrointestinal bleeding

The role of sigmoidoscopic examination in the diagnosis, evaluation, and treatment of minor lower gastrointestinal bleeding was investigated. A hundred patients with minor rectal bleeding were examined by rigid sigmoidoscopy under general anaesthesia between January 1989 and July 1996. Patients who had bleeding secondary to infections, anal fissure, or haemorrhoids were excluded from study. Patients were reviewed retrospectively according to their diagnosis and endoscopic and histopathological findings. Twenty nine of these patients were girls and 71 boys; their ages ranged between 8 month and 14 years (mean 7.2 years). Endoscopic pathological findings were established in 60 patients; 32 had rectal polyps, 16 non-specific proctitis, four solitary rectal ulcers, three internal haemorrhoids, two ulcerative colitis, two Hirschsprung's enterocolitis, and one haemangioma. It is concluded that sigmoidoscopic examination should be performed for the diagnosis, prognosis, and choice of treatment in patients with minor rectal bleeding and the diagnosis should be confirmed histopathologically.     

Takayasu's arteritis: assessment of disease activity with contrast-enhanced MR imaging

OBJECTIVE: The purpose of this study was to evaluate the role of contrast-enhanced MR imaging in the determination of disease activity in patients with Takayasu's arteritis. SUBJECTS AND METHODS: High-resolution contrast-enhanced T1-weighted spinecho MR imaging using small fields of view (14-20 cm) and thin slices (4-5 mm) was performed in 26 patients with Takayasu's arteritis and 16 healthy subjects. The degree of aortic mural enhancement was assessed by measuring signal intensity and by visually estimating it in comparison with that of the myocardium. RESULTS: Contrast-enhanced MR imaging showed more enhancement of thickened aortic wall compared with myocardium, thus suggesting active Takayasu's arteritis on MR imaging in 16 patients. Determination of disease activity using contrast-enhanced MR imaging was concordant with clinical findings in 23 patients (88.5%). Contrast-enhanced MR findings were concordant with laboratory findings in most patients (erythrocyte sedimentation rate in 92.3% [24/26] and C-reactive protein in 84.6% [22/26]). The measured signal intensity of the aortic wall relative to that of myocardium during the early phase of contrast-enhanced MR imaging correlated well with the erythrocyte sedimentation rate (r = 0.78, p < 0.005) and with the C-reactive protein level (r = 0.63, p < 0.005). CONCLUSION: Contrast-enhanced MR imaging provides information about disease activity of Takayasu's arteritis, which may be useful in the diagnosis and treatment of Takayasu's arteritis.