Carboplatin and vincristine chemotherapy for children with newly diagnosed progressive low-grade gliomas

OBJECTIVES: The purpose of this study was to identify behaviors associated with change in body mass index or with weight gain at the waist. METHODS: A cohort of 79236 White, non-Hispanic, healthy adults was questioned in 1982 and 1992 about diet and 10 physical activities. Estimates were made of the mean effects of stable behaviors on 10-year change in body mass index and on odds ratios for gain at the waist. RESULTS: Ten-year changes in body mass index was associated positively with meat consumption and smoking cessation and inversely with vegetable consumption, vitamin E supplementation, continued smoking, and some vigorous activities (e.g., jogging/running). Women's body mass index decreased with walking 4 or more hours per week and with regular alcohol intake, but these behaviors had a smaller effect on men's body mass index. weight gain was inversely associated with high vegetable consumption, walking 4 or more hours per week, and jogging/running 1 to 3 hours per week but not with less demanding physical activities. CONCLUSIONS: Simple derivation of behaviors associated with weight loss or reduced abdominal obesity may enhance programs designed to prevent obesity and chronic diseases.     

Reduction of pantethine in rabbit ocular lens homogenate

In several animal models, preliminary studies have indicated that pantethine may inhibit cataract formation. Therefore, preclinical trials need to be conducted to study the pharmacology of pantethine in the ocular lens and to establish its efficacy. Since pantethine, which is a disulfide, can undergo a variety of chemical modifications such as reduction and formation of mixed disulfides, a detailed study was first conducted to determine the stability of pantethine in rabbit lens homogenate. A knowledge of the stability of pantethine in lens homogenate was necessary to establish if pantethine could be metabolized in the time it takes to harvest and homogenize a lens. The results of this study will be used to establish a protocol for harvesting and homogenizing lens samples. Pantethine (100 microM) is completely reduced to pantetheine in rabbit lens homogenate in about 16 min. About 1.5% of the pantethine added to lens homogenate forms a mixed disulfide with lens proteins, and the remainder is found in the supernatant. The supernatant pantethine concentration decreases exponentially as a function of time, and the terminal half-life for this process is 3.3 min. The free supernatant pantetheine concentration increases in pseudo first order manner as a function of time with a rate constant of 4.3 min. Pantethinase activity is not significant, because the free supernatant pantetheine concentration did not decrease. The exact mechanism of pantethine reduction in rabbit lens homogenate remains to be determined.     

Structures of competitive inhibitor complexes of protocatechuate 3,4-dioxygenase: multiple exogenous ligand binding orientations within the active site

Protocatechuate 3,4-dioxygenase (3,4-PCD) catalyzes the oxidative ring cleavage of 3,4-dihydroxybenzoate to produce beta-carboxy-cis, cis-muconate. Crystal structures of Pseudomonas putida3,4-PCD [quaternary structure of (alphabetaFe3+)12] complexed with seven competitive inhibitors [3-hydroxyphenylacetate (MHP), 4-hydroxyphenylacetate (PHP), 3-hydroxybenzoate (MHB), 4-hydroxybenzoate (PHB), 3-fluoro-4-hydroxybenzoate (FHB), 3-chloro-4-hydroxybenzoate (CHB), and 3-iodo-4-hydroxybenzoate (IHB)] are reported at 2.0-2.2 A resolution with R-factors of 0. 0.159-0.179. The inhibitors bind in a narrow active site crevasse lined with residues that provide a microenvironment that closely matches the chemical characteristics of the inhibitors. This results in as little as 20% solvent-exposed surface area for the higher-affinity inhibitors (PHB, CHB, and FHB). In uncomplexed 3,4-PCD, the active site Fe3+ is bound at the bottom of the active site crevasse by four endogenous ligands and a solvent molecule (Wat827). The orientations of the endogenous ligands are relatively unperturbed in each inhibitor complex, but the inhibitors themselves bind to or near the iron in a range of positions, all of which perturb the position of Wat827. The three lowest-affinity inhibitors (MHP, PHP, and IHB) yield distorted trigonal bipyramidal iron coordination geometry in which the inhibitor C4-phenolate group displaces the solvent ligand. MHB binds within the active site, but neither its C3-OH group nor the solvent molecule binds to the iron. The C4-phenolate group of the three highest-affinity inhibitors (PHB, CHB, and FHB) coordinates the Fe3+ adjacent to Wat827, resulting in a shift in its position to yield a six-coordinate distorted octahedral geometry. The range of inhibitor orientations may mimic the mechanistically significant stages of substrate binding to 3, 4-PCD. The structure of the final substrate complex is reported in the following paper [Orville, A. M., Lipscomb, J. D., & Ohlendorf, D. H. (1997) Biochemistry 36, 10052-10066].     

Mutational analysis of the role of nucleoside triphosphatase P4 in the assembly of the RNA polymerase complex of bacteriophage phi6

Bacteriophage phi6 is a complex enveloped double-stranded RNA virus with a segmented genome and replication strategy quite similar to that of the Reoviridae. An in vitro packaging and replication system using purified components is available. The positive-polarity genomic segments are translocated into a preformed polymerase complex (procapsid) particle. This particle is composed of four proteins: the shell-forming protein P1, the RNA polymerase P2, and two proteins active in packaging. Protein P7 is involved in stable packaging, and protein P4 is a homomultimeric potent nucleoside triphosphatase that provides the energy for the RNA translocation event. In this investigation, we used mutational analysis to study P4 multimerization and assembly. P4 is assembled onto a preformed particle containing proteins P2 and P7 in addition to P1. Only simultaneous production of P1 and P4 in the same cell leads to P4 assembly on P1 alone, whereas the P1 shell is incompetent for accepting P4 if produced separately. The C-terminal part of P4 is essential for particle assembly but not for multimerization or enzymatic activity. Altering the P4 nucleoside triphosphate binding site destroys the ability to form multimers.     

Microanalysis of lung airway surface fluid by capillary electrophoresis with conductivity detection

The thin layer of fluid that covers the surface of the epithelia lining the conducting airways plays an important role in primary pulmonary defense, and its composition may be a critical factor in the pathogenesis of several lung diseases including cystic fibrosis. Despite its physiological importance, the composition of airway surface fluid (ASF) is poorly understood due to considerable difficulties in sample collection from the 5-30 microns thick layer and subsequent analysis. We have used a novel technique for sample collection and microanalysis of ASF (nanoliter sample required) by capillary electrophoresis with conductivity detection. Limitations on the diameters of capillary required for the sample injection process and for the conductivity detector require the use of coupled separation capillaries with different external diameters. Two different methods were used to construct a butt-joint coupling for capillaries of different outer diameters. Reasonable efficiency is observed with the coupled capillaries (N = 100000 plates m-1) compared to an unbroken single capillary (N = 180000 plates m-1). The use of conductivity detection allows greater flexibility in method development and the possibility of determining a greater variety of ions than with a previous indirect-UV method. In the present study, we describe the analysis of cations (Na+, K+, Ca2+, Mg2+) and anions (Cl-, NO2-, NO3-, SO4(2-), PO4(2-), HCO3-) in rat ASF. Particular attention was paid to developing washing procedures which limited fouling of the conductivity sensor. In healthy rats, ASF was found to be hypotonic compared to plasma levels, consistent with some observations made in human airways.     

Brain metastases in well-differentiated carcinoma of the thyroid

Fifteen patients (4 males and 11 females) developed brain metastases from well-differentiated thyroid cancer within 1 month to 14 years of the initial diagnosis. One patient presented with a brain tumor. Except for 3 patients with unique brain metastases, all the others had extensive metastases in nodes, lungs and bones in various combinations. Brain metastases generally appeared after the onset of metastases at other sites. The histology of the brain tumor matched the primary pathology in the 6 operated cases. The treatment was surgery and external radiation in 6 cases, and radioiodine or chemotherapy in the others. Survival in general was less than 6 months after the diagnosis of brain metastases. The prognosis is poor once the onset of brain metastases is evident.     

Use of laser Doppler flowmetry for estimation of the depth of burns

The trend for treatment of deep second degree burns and third degree burns is toward early excision and skin grafting. The ability to predict burn depth accurately as early as possible is important for early excision and skin grafting. This study, prospectively evaluated the ability of laser Doppler flow measurements, obtained within 72 hours after burn injury, to predict the depth of burn wounds. A Periflux system 4001 laser Doppler flowmeter was used to measure the cutaneous microflow circulation of 100 selected points of burn wounds on 44 inpatients and of 1680 selected points on 120 volunteers from March of 1993 to February of 1994. The mean value of superficial second degree burns checked by laser Doppler was 194.6 perfusion units (PU). The value of deep second degree burns was 59.7 PU, and the value of third degree burns was 5.1 PU. The mean normal cutaneous blood flow of 120 volunteers (control group) was between 4 and 9 PU, except on the head, neck, hand, and foot. Blood flow of more than 100 PU correctly predicted (90.2 percent of cases) a superficial second degree burn. Blood flow between 100 and 10 PU correctly predicted (96.2 percent of cases) a deep second degree dermal burn. That of less than 10 PU correctly predicted (100 percent of cases) a third degree burn. There was also a significant correlation between initial flow measurements and the depth of burn wounds. We conclude that laser Doppler flow measurements performed early after burn injury are useful in predicting the depth of burn wounds. Laser Doppler flowmetry has the advantage of being easy to use and noninvasive and of providing immediate results for early determination of burn depth. Laser Doppler flowmetry is useful in selecting patients for early excision and grafting of burn wounds.