Magnesium homeostasis during high-intensity anaerobic exercise in men

This study was conducted to determine whether short-term, high-intensity anaerobic exercise alters Mg homeostasis. Thirteen men performed intermittent bouts of treadmill running at 90% of their predetermined maximum O2 uptake until exhaustion on one occasion during a week in which all men were consuming a standard diet (115 mg Mg/1,000 kcal). Plasma and erythrocyte Mg concentrations and peripheral blood mononuclear cell Mg content were measured before and after the exercise. Complete 24-h urine collections were obtained on control days, on the day of exercise, and on the day after exercise. Exercise induced a transient but significant decrease in plasma Mg content (-6.8%; P less than 0.01); over 85% of the loss could be accounted for by a shift to the erythrocytes. Significant increases in urinary excretion of Mg were observed on the day of exercise (131.5 +/- 6.8 mg/day) compared with control days (108 +/- 6.6 mg/day), with the percent increase correlating with postexercise blood lactate concentration (r = 0.68; P less than 0.01) and oxygen consumption during recovery (r = 0.84; P less than 0.001). The data indicate that high-intensity anaerobic exercise induces intercompartmental Mg shifts in blood that return to preexercise values within 2 h and urinary losses on the day of exercise that return to base line the day after exercise. It is postulated that the exercise-induced increase in Mg excretion may depend on the intensity of the exercise, and the relative contribution of anaerobic metabolism to the total energy expended during exercise.     

Trace metal uptake by garden herbs and vegetables

In many regions of Iran, crops are irrigated with municipal and industrial wastewater that contain a variety of metals. The purpose of this study was to simulate the level of metals that may be presented to plants over a growing season in a controlled laboratory setting. Cadmium, lead, arsenic, chromium, mercury, nickel, copper, zinc, and selenium were applied to plants at the high rate of 200 g metal/ha/wk. The following plants were examined for metal accumulation and effects on yield: garden cress (Lipidium sativum), leek (Allium porrum L.), basil (Ocimum basilicum L.), mint (Mentha arvensis L.), onion (Allium capa L.), radish (Raphanus sativus L.), and tarragon (Artemisia draculus L.). All plants showed significant uptake of all metals when compared to control (p=0.05), and growth was significantly reduced (p=0.05). Cadmium and chromium levels of 85±7.4 and 47.6±8.9 μg/g); selenium levels were highest in tarragon (16.5±5.8 μg/g). Zinc levels were similar (p=0.05) in all species tested, as were mercury and lead. The remaining metals (nickel and copper) showed significant differences in uptake, depending on plant species.     

Sequences encoding two trypsin inhibitors occur in strikingly similar genomic environments.

The nucleotide sequences of two approx. 4 kilobase pair segments of the bovine genome are presented. One segment contains a coding region for bovine pancreatic trypsin inhibitor (BPTI) and the other segment contains a coding region for a BPTI homologue. The two 4 kilobase pair sequences are strikingly similar over approx. 3.4 kilobase pairs of their sequence, including putative intron sequences, suggesting that they have evolved from a gene duplication event.     

Kidney glomerular explants in serum-free media. Sequential morphologic and quantitative analysis of cell outgrowths

Guinea pig glomeruli were grown in vitro for 22 days in a serum-free medium composed of Waymouth's MB 752/1 supplemented with sodium pyruvate, nonessential amino acids, antibiotics, insulin, transferrin, selenium, triiodothyronine, and fibronectin (FN), and sequential morphologic and quantitative studies of cell outgrowth were performed. Glomeruli grown in serum-free medium showed preservation of glomerular visceral epithelial cells but extensive necrosis of endocapillary cells (endothelial and mesangial cells). Morphologic analysis demonstrated progressive morphologic changes in cultured glomerular cells; however, most cell types observed in culture appeared to grow from the epithelial side of the glomerular basement membrane. Mitosis was a prominent component of glomerular cell outgrowth in vitro, and total DNA increased slightly during glomerular culture. FN was required for glomerular cell outgrowth, and studies using FN fragments demonstrated that the carboxy-terminal portion of FN was required for whole glomerular attachment. These results are used to develop a model for glomerular cell outgrowth in vitro.     

Fast atom bombardment: evidence of disproportionation and recombination of a synthetic porphyrin in the matrix

In addition to dimerization and polymerization of samples as previously suggested, it appears that during FAB-MS, reactions in the sample matrix can occur to yield new compounds that are recombinations of molecular fragments. This type of reaction may be especially critical to the integrity of peptide sequencing using FAB, since the reactions cited in this report involve the formation and rupture of amides or peptide bonds.     

Regulation of Nostoc sp. phycobilisome structure by light and temperature.

Nostoc sp. strain MAC cyanobacteria were green in color when grown in white light at 30 degrees C and contained phycobilisomes that had phycoerythrin and phycocyanin in a molar ratio of 1:1. Cells grown for 4 to 5 days in green light at 30 degrees C or white light at 39 degrees C turned brown and contained phycoerythrin and phycocyanin in a molar ratio of greater than 2:1. In addition to the change in pigment composition, phycobilisomes from brown cells were missing a 34.5-kilodalton, rod-associated peptide that was present in green cells. The green light-induced changes were typical of the chromatic adaptation response in cyanobacteria, but the induction of a similar response by growth at 39 degrees C was a new observation. Phycobilisomes isolated in 0.65 M phosphate buffer (pH 7) dissociate when the ionic strength or pH is decreased. Analysis of the dissociation products from Nostoc sp. phycobilisomes suggested that the cells contained two types of rod structures: a phycocyanin-rich structure that contained the 34.5-kilodalton peptide and a larger phycoerythrin-rich complex. Brown Nostoc sp. cells that lacked the 34.5-kilodalton peptide also lacked the phycocyanin-rich rod structures in their phycobilisomes. These changes in phycobilisome structure were indistinguishable between cells cultured at 39 degrees C in white light and those cultured at 30 degrees C in green light. A potential role is discussed for rod heterogeneity in the chromatic adaptation response.     

Nutrient control of brain neurotransmitter synthesis and function

Dietary fluctuations in nutrient availability are factors in the regulation of brain function. Until recently the prevailing view was that brain biochemistry and function were influenced by diet only when biochemical and clinical evidence of nutrient deficiency was present. It is now clear, however, that the brain is sensitive and responsive to diet composition. Preliminary data show that variation in vitamin and mineral nutrient intakes over ranges that are considered to maintain normal nutritional status may impact on brain biochemistry, owing to their many coenzyme roles. Furthermore, the synthesis of at least five brain neurotransmitters, namely serotonin, the catecholamines, acetylcholine, histamine, and glycine responds to dietary fluctuations in availability of their nutrient precursors, tryptophan, tyrosine, choline, histidine, and threonine, respectively. Not only are these biochemical events altered by normal variations in diet composition, but considerable evidence now exists to show that the brain uses this information to regulate many functions. Future studies can be expected to continue to elucidate the links between diet, brain neurotransmission, and brain function, and to exploit the application of these links in understanding the function of the brain under normal and disease conditions.     

Simple and rapid method for isolating large plasmid DNA from lactic streptococci.

A procedure for the rapid isolation of plasmid DNA larger than 30 megadaltons from lactic streptococci is described. This protocol can be used on a preparative scale to isolate sufficient quantities of plasmid DNA required for restriction analysis, cloning, or transformation experiments. A scaled-down protocol is very useful for rapidly screening the plasmid content of streptococcal strains. With this methodology, previously undetected large plasmids were observed.     

Choriocarcinoma metastatic to the lung. A cytologic study with identification of human choriogonadotropin with an immunoperoxidase technique

A case of choriocarcinoma metastatic to the lung following a previous hydatidiform mole is presented. It was possible to make definitive identification of trophoblastic elements on a needle aspiration biopsy using an immunoperoxidase staining technique, thus avoiding diagnostic thoracotomy prior to therapeutic intervention. A method of immunoperoxidase staining of previously fixed and Papanicolaou-stained needle aspiration biopsy specimens is also described, and other uses of the immunoperoxidase technique on needle biopsy specimens are discussed.