Brain creatine kinase with aging in F-344 rats: analysis by saturation transfer magnetic resonance spectroscopy.

We measured in vivo forward flux of the creatine kinase reaction in rat forebrain in young (Y: 6 month, n = 13), mid-aged (M: 12 month, n = 7) and aged (O: 27 month, n = 10) animals using 31P magnetic resonance saturation transfer. Forward flux was reduced in the aged rats (Y: 0.42 +/- 0.08; M: 0.41 +/- 0.10; O: 0.31 +/- 0.03 s(-1) +/- SD; p = 0.008 O vs. Y). In vitro studies in a subset of the same rats showed a parallel decline in CK activity (Y: 2.16 +/- 0.40; M: 2.17 +/- 0.25; O: 1.56 +/- 0.06 IU +/- S.D.; p = 0.002 O vs. Y). The in vivo spectroscopic and in vitro biochemical measures were significantly correlated. Reduced creatine kinase activity could account for the observed decreased forward flux in aging brain. Intracellular pH, phosphocreatine/inorganic phosphate ratio, and phospocreatine/gamma-adenosine triphosphate ratio did not differ between groups. Forward flux may represent a better measure of brain energy function than relative phosphocreatine or adenosine triphosphate levels observable in vivo.

Near-infrared spectrophotometric monitoring of stroke-related changes in the protein and lipid composition of whole gerbil brains.

Strokes are a critical problem in the U.S. that affect more than 500,000 people annually. Research into the causes of stroke and testing of drug therapies to reduce ischemic and postischemic damage to the brain is frustrated by an inability to continuously follow the physical and chemical events that occur during ischemia and reperfusion in vivo. Near-IR spectrometry is used in this paper to observe stroke-induced changes in the lipids and proteins of whole brain samples and in intact subjects. The examination of whole brains is made possible by a combination of hardware and software techniques designed to make the sample presentation to the spectrometer more reproducible. Near-IR spectrophotometry of brain tissue discriminates between adult (3-4 months of age) and aged (18-20 months of age) brains as well as between brains exposed to 5- and 10-min ischemia. The near-IR analytical method has many applications in aging and stroke research, including the noninvasive determination of age from brain spectra obtained transcranially, simultaneous multicomponent analysis of lipids and proteins, and quantification of edema.

MRI evaluation of pigmented skin tumors. Preliminary study.

Magnetic resonance imaging (MRI) was performed in 16 patients with pigmented skin lesions, seven with nodular melanomas, two with superficial spreading melanomas, two with subcutaneous melanoma metastases, and five with different benign pigmented nodular skin lesions. The results of MRI were compared with the histologic diagnoses. Signal intensities of the lesions were compared with subcutaneous fat, revealing a lower signal intensity of all lesions on T1-weighted images. Intensity measurements showed a significant (P less than .01) difference between benign and malignant lesions on T2-weighted images.

Decreased sensitivity of early imaging with In-111 oxine-labeled leukocytes in detection of occult infection: concise communication.

Imaging with leukocytes labeled with indium-111 oxine is a sensitive technique for detecting sites of occult infection. Traditionally, imaging is performed 24 hr after injection. We undertook a prospective study of 35 patients (40 studies) with possible occult infection to see whether a 24-hr delay in imaging is really necessary. Patients were imaged at 1-4 hr and again at 24 hr after injection. The early images had a sensitivity of only 33%, compared with 95% for the 24-hr images. Of the seven studies that were positive on both early and delayed images, 71% had more intense uptake at 24 hr. There were no false-positive early images. We conclude that imaging 1-4 hr after injection with In-111 oxine-labeled leukocytes has a low sensitivity for detecting occult infection. However, a positive early image is specific for a site of infection.