Aluminum-induced defective mitochondrial metabolism perturbs cytoskeletal dynamics in human astrocytoma cells.

Although aluminum (Al), a known environmental toxin, has been implicated in a variety of neurological disorders, the molecular mechanism responsible for these conditions is not fully understood. In this report, we demonstrate the ability of Al to trigger mitochondrial dysfunction and ineffective adenosine triphosphate (ATP) production. This situation severely affected cytoskeletal dynamics. Whereas the control cells had well-defined structures, the Al-exposed astrocytoma cells appeared as globular structures. Creatine kinase (CK) and profilin-2, two critical modulators of cellular morphology, were markedly diminished in the astrocytoma cells treated with Al. Antioxidants such as alpha-ketoglutarate and N-acetylcysteine mitigated the occurrence of the globular-shaped cells promoted by Al toxicity. Taken together, these data reveal an intricate link between ATP metabolism and astrocytic dysfunction and provide molecular insights into the pathogenesis of Al-induced neurological diseases.

Blue native polyacrylamide gel electrophoresis and the monitoring of malate- and oxaloacetate-producing enzymes.

We demonstrate a facile blue native polyacrylamide gel electrophoresis (BN-PAGE) technique to detect two malate-generating enzymes, namely fumarase (FUM), malate synthase (MS) and four oxaloacetate-forming enzymes, namely pyruvate carboxylase (PC), phosphoenolpyruvate carboxykinase (PEPCK), citrate lyase (CL) and aspartate aminotransferase (AST). Malate dehydrogenase (MDH) was utilized as a coupling enzyme to detect either malate or oxaloacetate in the presence of their respective substrates and cofactors. The latter four oxaloacetate-forming enzymes were identified by 2,6-dichloroindophenol (DCIP) and p-iodonitrotetrazolium (INT) while the former two malate-producing enzymes were visualized by INT and phenazine methosulfate (PMS) in the reaction mixtures, respectively. The band formed at the site of enzymatic activity was easily quantified, while Coomassie staining provided information on the protein concentration. Hence, the expression and the activity of these enzymes can be readily evaluated. A two-dimensional (2D) BN-PAGE or SDS-PAGE enabled the rapid purification of the enzyme of interest. This technique also provides a quick and inexpensive means of quantifying these enzymatic activities in normal and stressed biological systems.

Expression of G protein alpha subunits in normal rat colon and in azoxymethane-induced colonic neoplasms.

BACKGROUND & AIMS: Heterotrimeric G proteins are important in growth-regulating signal transduction. The aim of this study was to characterize the relative expression of G protein alpha subunits in rat colonocytes, colonocyte antipodal plasma membranes, and colonic neoplasms. METHODS: Antipodal plasma membranes were prepared from isolated colonocytes. Azoxymethane was administered to rats to induce colonic neoplasms. K-ras mutations in the neoplasms were determined by oligonucleotide hybridization and confirmed by primer mediated-restriction fragment length polymorphism. Colonocyte and tumor homogenates or membranes were probed for Galpha subunits by Western blotting with isoform-specific antibodies. RESULTS: The expressions of Galphai2, alphai3, and alphaq/11 were significantly enriched in the basolateral compared with brush border fraction of colonic antipodal plasma membranes. In neoplasms without K-ras mutations, the expression of Galphai2 increased 4-fold, Galphas(long) increased 2.5-fold, and Galphai3 increased 1.5-2-fold. Expression did not differ among tumor grades. K-ras mutations were associated with lowered expression of G proteins, especially Galphao. CONCLUSIONS: In colonocytes, Galpha subunits are localized primarily in basolateral plasma membranes. The increased expressions of Galphai2 and, to a lesser degree, Galphai3 and Galphas(long) in tumors was independent of tumor grade but was modulated by the presence of K-ras mutations.

The outcome of triplet pregnancies at Hartford Hospital--1989-1996.

The advent of artificial induction of ovulation has increased the incidence of triplet pregnancies. Although the outcome of triplet pregnancies has improved through advanced technology, several studies have suggested that triplets conceived by artificial induction of ovulation have worse prenatal and perinatal outcomes than those conceived naturally. Our study examined the outcome of 14 sets of triplets conceived at Hartford Hospital between 1989 and 1996. Five of 14 sets of triplets were conceived by artificial methods and nine of 14 were conceived naturally. The mean gestational age was 31.8 weeks for artificially conceived infants vs 29.7 weeks for naturally conceived infants. Average weight at birth was 1.625 kg in the artificially conceived study group and 1.377 kg in the naturally conceived group. Time spent in the neonatal intensive care unit was 4.67 weeks for the artificially conceived study group and 3.57 weeks for the naturally conceived group. It is concluded that there was no difference in outcome in the triplets conceived by artificial induction of ovulation vs natural conception. Maternal age and sex of triplets were important factors determining perinatal outcomes of triplets.

Pulmonary embolism as a complication of long-term total parenteral nutrition.

Although much has been written concerning the complications of long-term total parenteral nutrition, little or no mention of pulmonary embolism is made in the literature. We present two patients maintained on home total parenteral nutrition who suffered pulmonary emboli, one while receiving standard heparin therapy. No potential source other than their indwelling total parenteral nutrition catheter was identified. Studies have revealed catheter-related thrombosis in up to 50% of patients with indwelling central venous catheters. Although early surgical literature suggested that upper extremity deep vein thromboses rarely embolize, more recent investigations have proven this false. In fact, the risk of pulmonary emboli appeared to be greatest in those thrombi that were catheter related. Because of this risk, we suggest a hypercoaguable work-up in any patient with a history of recurrent thrombosis. Heparin is central to the current preventive regimens; however, further study is needed to determine the most efficacious dose. Future development of less thrombogenic catheters will also be of assistance. Thrombolytic agents currently have an expanding role in the treatment of thrombotic complications. Whether they will have a future role in prevention remains unknown.

Hypertension: heavy metals, useful cations and melanin as a possible repository.

Popular belief has often attributed the disproportionate occurrence of hypertension in blacks to the increased social stresses faced by the minority population. Evidence now points to a more biologically relevant explanation of black hypertension, an increase in levels of heavy metals. Preferentially bound to melanin, cadmium, lead, and copper have implications not only in the etiology of black hypertension, but in the etiology of all hypertension. Of course, hypertension is heterogeneous by nature and cannot be attributed solely to any single cause. However, the indictment of the heavy metals, as well as a deficiency of other cations such as calcium, magnesium, and potassium, warrants a more nutritional approach and less reliance on current pharmacological therapy in selected cases. Melanin should be investigated as a storage bank for useful cations. If real, such a cation reservoir would explain the heat tolerance capacity of blacks and other dark-skinned tropical races.