The effect of vitamin E on lipid peroxidation in the copper-deficient rat

The present study was designed to determine whether the supplementation of vitamin E in the copper-deficient diet would ameliorate the severity of copper deficiency in fructose-fed rats. Lipid peroxidation was measured in the livers and hearts of rats fed a copper-deficient diet (0.6 microg Cu/g) containing 62% fructose with adequate vitamin E (0.1 g/kg diet) or supplemented with vitamin E (1.0 g/kg diet). Hepatic lipid peroxidation was significantly reduced by vitamin E supplementation compared with the unsupplemented adequate rats. In contrast, myocardial lipid peroxidation was unaffected by the level of vitamin E. Regardless of vitamin E supplementation, all copper-deficient rats exhibited severe signs of copper deficiency, and some of the vitamin E-supplemented rats died of this deficiency. These findings suggest that although vitamin E provided protection against peroxidation in the liver, it did not protect the animals against the severity of copper deficiency induced by fructose consumption.     

Incidence of three cross-reactive idiotypes on human rheumatoid factor paraproteins

The basis for rheumatoid factor (RF) production in autoimmune or lymphoproliferative diseases cannot be understood without defining the molecular factors that dictate RF structure and specificity. Recently three different mAb (6B6.6, 17.109, and G6) have been developed that define cross-reactive idiotypes (CRI) on intact L or H chains of human monoclonal RF cryoglobulins. However, the true incidence of these CRI among RF and their relationship to each other have not been delineated. In the present experiments, a panel of 163 randomly selected IgM paraproteins was evaluated for the expression of the two kappa L chain CRI, 6B6.6 and 17.109, and the H chain CRI, G6. Among the paraproteins with kappa L chains, 14% expressed the 17.109 CRI, and 9% expressed the 6B6.6 CRI. Both ELISA and Western immunoblotting experiments showed that the two L chain CRI were mutually exclusive. Anti-IgG activity was documented in 22 of the IgM-kappa paraproteins, among which mAb 6B6.6 reacted with 7 (32%) and mAb 17.109 with 6 (27%). Both CRI were expressed exclusively by L chains within the kappaIII variable gene subgroup. Although 17.109 CRI+ paraproteins had kappaIIIb L chains, none of the 6B6.6 CRI+ paraproteins possessed L chains with this kappa sub-subgroup specific Ag. The G6 CRI was found predominantly among RF paraproteins and was frequently yet not exclusively associated with the 17.109 CRI+ L chains. Additional experiments were performed on a panel of normal adult human sera and documented the presence of 6B6.6 and 17.109 CRI on a small percentage (0.1 to 2.0%) of IgM from most individuals. These data indicate that 1) the mAb 6B6.6 and 17.109 identify two major and distinct CRI among IgM-RF paraproteins, 2) both CRI are associated exclusively with kappaIII L chains, 3) kappaIIIb and kappaIII non-b L chains are equally prevalent among IgM-RF, 4) the G6 H chain CRI is frequently associated with 17.109 CRI+ L chains, but not with 6B6.6 CRI+ L chains, and 5) although the ability to make 6B6.6 and 17.109 CRI+ kappa L chains is common in humans, these CRI are present in low concentrations in normal IgM.     

Pulmonary epithelial sieving of small solutes in rat lungs

Transport and consumption of glucose from the air spaces of isolated, fluid-filled lungs can result in significantly lower glucose concentrations in the air spaces than in the perfusate compartment (11). This concentration difference could promote the osmotic movement of water from the air spaces to the perfusate, but the rate of fluid extraction from the air spaces would then be limited by the rates of electrolyte transport through the epithelium. In the present study, measurements were made of solute and water losses from the air spaces of fluid-filled rat lungs and the transport of these solutes and water into the vasculature after addition of hypertonic glucose or sucrose to the perfusate. Increases in the concentrations of Na+, Cl-, K+, and labeled mannitol in the air space were initially comparable to those of albumin labeled with Evans blue. Similarly, decreases in electrolyte concentrations in the perfusate were comparable to those of labeled albumin, indicating that very little solute accompanied the movement of water out of the lungs. Nor was evidence found that exposure of the vasculature to hypertonic glucose resulted in an increase in the rate at which fluid was reabsorbed from the air spaces over a 1-h interval, aside from an initial, abrupt loss of solute-free water from the lungs. These observations suggest that perfusion of fluid-filled lungs with hypertonic solutions of small solutes results in the extraction of water from the air spaces and pulmonary parenchyma across membranes that resist the movement of electrolytes and other lipophobic solutes.     

Glucocorticoid-induced osteoporosis: a cross-sectional study.

We studied 70 patients (48 women and 22 men) with either rheumatic disease (n = 25) or lung disease (n = 45) who had been treated with glucocorticoids for at least 6 months (mean cumulative dose, 24.2 +/- 27.1 g of prednisone; mean current dose, 11.0 +/- 8.6 mg/d, mean duration of therapy, 8.1 years. We measured bone mineral density (BMD) of the hip (femoral neck) and spine (L2-L4) using dual-photon absorptiometry and BMD of the distal one third radius using single-photon absorptiometry. Compared with age-matched controls, the study population had decreased BMD of the spine (87.0%), hip (87.2%), and radius (90.6%). Current dose, cumulative dose, and duration of therapy were not correlated with BMD in the spine or hip in the total study population. The most significant correlations with low bone mass at the hip and spine were short height and low weight. There was a high incidence of hypercalciuria (30%) as compared with an age- and sex-matched control group (6.4%). Glucocorticoids are known to decrease vertebral and radial bone density. We conclude that glucocorticoids also decrease hip bone density as measured at the femoral neck. The high incidence of hypercalciuria may have implications for therapy of glucocorticoid-induced osteoporosis.     

Fine needle aspiration cytology of neuroblastoma, including peripheral neuroectodermal tumor, with immunocytochemical and ultrastructural confirmation

Eleven fine needle aspiration (FNA) biopsies were performed on seven children with neuroblastoma, including one patient with a congenital neuroblastoma and another with a peripheral neuroblastoma of the thoracopulmonary region. FNA cytology made the primary diagnosis of neuroblastoma in four of the seven cases. The other biopsies documented local recurrences and metastases to liver, lymph nodes, orbit and breast. The cytologic features included varying numbers of small primitive cells with scanty cytoplasm, poorly to well-formed pseudorosettes, cell processes, a fibrillary matrix and multinucleated ganglion cells. Five of the seven patients had electron microscopic (EM) examination of the FNA specimen, which in all cases confirmed the diagnosis. Batteries of immunoperoxidase stains were performed on all 11 aspirates with variable results. Staining for neuron-specific enolase was positive in four of the five neoplasms tested, although strongly positive in only three of the cases. Staining for neurofilament markers was positive in only two of five tumors. Studies for cytokeratin markers (AE1/3), low-molecular-weight cytokeratin (35BH11), hematopoietic markers (T29/33), immunoglobulin light chains and myoglobin were negative. One case was positive for vimentin. This study attests to the value of FNA cytology in suggesting a correct diagnosis of either primary, recurrent or metastatic neuroblastoma in children. Selective use of immunoperoxidase stains and EM on the aspirates may be of value.     

Inactivation of gamma-aminobutyric acid aminotransferase by (Z)-4-amino-2-fluorobut-2-enoic acid

(Z)-4-Amino-2-fluorobut-2-enoic acid (1) is shown to be a mechanism-based inactivator of pig brain gamma-aminobutyric acid aminotransferase. Approximately 750 inactivator molecules are consumed prior to complete enzyme inactivation. Concurrent with enzyme inactivation is the release of 708 +/- 79 fluoride ions; transamination occurs 737 +/- 15 times per inactivation event. Inactivation of [3H]pyridoxal 5'-phosphate ([3H]PLP) reconstituted GABA aminotransferase by 1 followed by denaturation releases [3H]PMP with no radioactivity remaining attached to the protein. A similar experiment carried out with 4-amino-5-fluoropent-2-enoic acid [Silverman, R. B., Invergo, B. J., & Mathew, J. (1986) J. Med. Chem. 29, 1840-1846] as the inactivator produces no [3H]PMP; rather, another radioactive species is released. These results support an inactivation mechanism for 1 that involves normal catalytic isomerization followed by active site nucleophilic attack on the activated Michael acceptor. A general hypothesis for predicting the inactivation mechanism (Michael addition vs enamine addition) of GABA aminotransferase inactivators is proposed.     

Localization of a human gene homologous to the PrP gene on the p arm of chromosome 20 and detection of PrP-related antigens in normal human brain

Infectious fractions prepared from scrapie-infected hamster brains contain a protein, PrP 27-30, which shares antigenic determinants with polypeptides found in similarly prepared fractions from patients with Creutzfeldt-Jakob disease. cDNA sequences encoding the hamster PrP 27-30 identified homologous sequences in the human genome as well as in normal human brain mRNA preparations. Antibodies raised against the mouse PrP's identified antigenically related peptides in both normal hamster and human brain as well as in scrapie-infected hamster brain and CJD-affected human brain. By using in situ hybridization we localized the homologous human genomic sequences on the short arm of chromosome 20. Our results indicate that the reportedly unique proteins detected in human CJD preparations derive from normal human gene products.     

Activation of 2-5A-dependent RNase by analogs of 2-5A (5'-O-triphosphoryladenylyl(2'----5')adenylyl(2'----5')adenosine ) using 2',5'-tetraadenylate (core)-cellulose

A variety of 2-5A (px(A2'p)nA; x = 2 or 3, n greater than or equal to 2) analogs were assayed for their abilities to activate murine 2-5A-dependent RNase (subsequently "the nuclease") using a recently developed method. This technique consists of immobilizing and partially purifying the nuclease using core-cellulose [A2'p)3A-cellulose) and then monitoring the breakdown of poly(U)-3'-[32P]Cp into acid-soluble fragments. Several 5'-adenosinecapped analogs of 2-5A (containing a tetra-, tri-, or diphosphate) were analyzed, and it was found that reducing the number of phosphoryl groups between the 5' to 5'-diadenosine linkages resulted in a progressive loss of activity. Because A5' pppp(A2'p)3A was a potent activator of the nuclease yet stable during the assay these results suggested that a free 5'-phosphoryl group may not be required for the activation of the nuclease. A number of 8-bromoadenosine-substituted analogs of 2-5A were also studied. Curiously, the brominations decreased the activities of the 5'-di- and triphosphorylated molecules while substantially increasing the activities of the 5'-monophosphorylated species. The results indicated that a tri- or diphosphate moiety on the 5'-end of 2-5A or the presence of ATP is not absolutely required for the nuclease to be active. Furthermore, the ATP analog, beta, gamma-methylene ATP, did not inhibit the activity of the nuclease. Finally, a 3',5'-phosphodiester linkage isomer of 2-5A and a 3'-deoxy (cordycepin) analog of 2-5A were tested, and both were found to be completely without activity.     

Movement of ions and small solutes across endothelium and epithelium of perfused rabbit lungs

In situ and isolated fluid-filled rabbit lungs were used to study the transport of indicators between the air space and vascular compartments. These indicators were placed in either the perfusate or air spaces and samples were collected from the perfusate at intervals during a 1-h perfusion period. At the end of the hour, fluid was pumped out of the air space compartment into serial tubes and indicator concentrations were determined in both the air space and perfusion fluids. One hour after introducing the indicators into the air space, the relative decreases in solute concentration were (arranged from the greatest to the least decline): [14C]urea greater than 36Cl- = 125I- greater than 22Na+ greater than [3H]mannitol. The relative rates at which the indicators appeared in the perfusate were similar. When the indicators were placed in the perfusate, a similar relationship was observed in the increase in air space concentrations, but the loss of 22Na+ from the perfusate was similar to those of 36Cl- and 125I-. Losses of all indicators from the perfusate were two or more times those from the air spaces, and although the loss of [3H]mannitol from the perfusate was similar to that of 22Na+ for about 30 min, subsequent loss was much slower. Very little 125I-albumin traversed the tissue barrier, and the small changes in the concentrations of 125I-albumin in the air spaces suggested that little fluid movement had occurred. These studies suggest that the epithelium is less permeable to solutes than the endothelium and permits passage of anions at a faster rate than 22Na+.(ABSTRACT TRUNCATED AT 250 WORDS)