Adaptability in enzymes

In studying inhibitors and activators of enzymes it has often been found that inhibitors act as activators when in very low concentrations and that certain activators (in suitable concentrations) show inhibition. Similar results were obtained in the present work in studying urease from soya bean in the presence of lead acetate. Lead acetate is normally an inhibitor of urease. It was found, however, that in small concentrations of lead acetate increase in the activity of urease occurs. On prolonging the time of the reaction inhibition develops and still later increased enzymatic activity again occurs. The results were elaborated statistically and are discussed in relation to the use of “adaptation” of urease in unfavourable conditions in reaction mixtures by the action of lead acetate.     

Lithium in drinking water and the incidences of crimes,suicides, and arrests related to drug addictions

Using data for 27 Texas counties from 1978-1987, it is shown that the incidence rates of suicide, homicide, and rape are significantly higher in counties whose drinking water supplies contain little or no lithium than in counties with water lithium levels ranging from 70-170 micrograms/L; the differences remain statistically significant (p less than 0.01) after corrections for population density. The corresponding associations with the incidence rates of robbery, burglary, and theft were statistically significant with p less than 0.05. These results suggest that lithium has moderating effects on suicidal and violent criminal behavior at levels that may be encountered in municipal water supplies. Comparisons of drinking water lithium levels, in the respective Texas counties, with the incidences of arrests for possession of opium, cocaine, and their derivatives (morphine, heroin, and codeine) from 1981-1986 also produced statistically significant inverse associations, whereas no significant or consistent associations were observed with the reported arrest rates for possession of marijuana, driving under the influence of alcohol, and drunkenness. These results suggest that lithium at low dosage levels has a generally beneficial effect on human behavior, which may be associated with the functions of lithium as a nutritionally-essential trace element. Subject to confirmation by controlled experiments with high-risk populations, increasing the human lithium intakes by supplementation, or the lithiation of drinking water is suggested as a possible means of crime, suicide, and drug-dependency reduction at the individual and community level.     

Production of fungal rennet byMucor miehei using solid state fermentation

Summary Investigations have been carried out on the production of fungal rennet using a thermophilic strain ofMucor miehei under solid state fermentation conditions. A high milk clotting enzyme activity (58000 Soxhlet units/g) was achieved when optimum conditions were used. Further, a high ratio of 6.6:1 between milk clotting and proteolytic activities for this enzyme was obtained. Cheese prepared using this enzyme was also found to be acceptable in organoleptic quality. Large scale production of the enzyme in trays using the optimum conditions gave milk-clotting enzyme activities comparable to those in flask experiments.     

Free Radical Formation by Ultrasound in Aqueous Solutions. A Spin Trapping Study

Our recent spin trapping studies of free radical generation by ultrasound in aqueous solutions are reviewed. The very high temperatures and pressures induced by acoustic cavitation in collapsing gas bubbles in aqueous solutions exposed to ultrasound lead to the thermal dissociation of water vapor into H atoms and OH radicals. Their formation has been confirmed by spin trapping. Sonochemical reactions occur in the gas phase (pyrolysis reactions), in the gas-liquid interfacial region, and in the bulk of the solution (radiation-chemistry reactions). The high temperature gradients in the interfacial regions lead to pyrolysis products from non-volatile solutes present at sufficiently high concentrations. The sonochemically generated radicals from carboxylic acids, amino acids, dipeptides. sugars, pyrimidine bases. nucleosides and nucleo-tides were identified by spin trapping with the non-volatile spin trap 3.5-dibromo-2.6-dideuterio-4-nitrosobenzenesulfonate. At low concentrations of the non-volatile solutes. the spin-trapped radicals produced by sonolysis are due to H atom and OH radical reactions. At higher concentrations of these non-volatile solutes, sonolysis leads to the formation of additional radicals due to pyrolysis processes (typically methyl radicals). A preferred localization of non-volatile surfactants (compared to analogous non-surfactant solutes) was demonstrated by the detection of pyrolysis radicals at 500-fold lower concentrations. Pyrolysis radicals were also found in the sonolysis of aqueous solutions containing only certain nitrone spin traps. The more hydrophobic the spin trap, the lower the concentration at which the pyrolysis radicals can be observed. The effect of varying the temperature of collapsing transient cavities in aqueous solutions of different rare gases and of N₂O on radical yields and on cell lysis of mammalian cells was investigated.     

Complete1H NMR assignments of synthetic glycopeptides from the carbohydrate-protein linkage region of serglycins

We present complete¹H NMR assignments for two synthetic glycopeptides representative of the carbohydrateprotein linkage region of serglycin proteoglycans. The peptides are: Ser(Galp-Xylp)-Gly-Ser-Gly-Ser(Galp-Xylp)-Gly and, Ser(Galp-Xylp)-Gly-Ser(Galp-Xylp)-Gly-Ser(Galp-Xylp)-Gly. A number of 2D NMR spectra together with a 3D NOESY-TOCSY spectrum were acquired at 600 MHz to complete the assignments of the glycopeptides dissolved in water with 40% trifluoroethanol. Preliminary analysis of the NMR data suggests folded structures for the glycopeptides.A preliminary account of this work was presented at an International Symposium held at the University of Alabama at Birmingham in November, 1994 on the occasion of the 65th birthday of Professor Lennart Rodén.     

Some events of mitosis and cytokinesis in the generative cell of Ornithogalum virens L.

The organization of the microtubule (Mt) cytoskeleton during mitosis and cytokinesis of the generative cell (GC) in Ornithogalum virens L. (bicellular pollen type, chromosome number, n = 3) from prophase to telophase/sperm formation was investigated by localization of -tubulin immunofluorescence using a conventional fluorescence microscope and a confocal laser scanning microscope. Chromosomes were visualized with DNA-binding fluorochrome dyes (ethidium bromide and 46-diamino-2-phenyl-indole). The GC of O. virens is characterized by G2/M transition within the pollen grain and not in the pollen tube as occurs in the majority of species with bicellular pollen. It was found that prophase in the GC starts before anthesis and prometaphase takes place after 10 min of pollen germination. The prophase Mts are organized into three prominent bundles, located near the generative nucleus. The number of these Mt bundles is the same as the number of GC chromosomes, a relation which has not previously been considered in other species. The most evident feature in the prophase/ prometaphase transition of O. virens GC is a direct rapid rearrangement of Mt bundles into a network which appears to interact with kinetochores and form a typical prometaphase Mt organization. The metaphase chromosomes are arranged into a conventional equatorial plate, and not in tandem as is thought to be characteristic of GC metaphase. The metaphase spindle consists of kinetochore fibres and a few interzonal fibres which form dispersed poles. Anaphase is characterized by a significant elongation of the mitotic spindle concomitant with the extension of the distance between the opposite poles. At anaphase the diffuse poles converge. Cytokinesis is realized by cell plate formation in the equatorial plane of the GC. The phragmoplast Mts between two future sperm nuclei appear after Mts of the mitotic spindle have disappeared.Abbreviations DAPI 46-diamino-2-phenyl-indole - GC generative cell - GN generative nucleus - Mt microtubule This research was made possible in part due to TEMPUS Programme and Global Network for Cell and Molecular Biology UNESCO grants to Magorzata Bana. The experimental part of the work was done in Siena University. M. Banas is very grateful to Prof. Mauro Cresti and his group for scientific interest, offering the excellent laboratory facilities, and kind reception.     

Microcomputer BASIC programs for rapid determination of lethal dosages of biocides using logit transformations

The probit analysis model is generally used for the deterininationof lethal dosages in bioassay applications. However, the logitmodels, which use the logistic curve instead of the integratednonnal curve, could also be effectively used for the determinationof lethal dosages and regression coefficients. In this paper,two lypes of logit models, namely minimum logit chi square andmaximum likelihood, have been described in detail for the estimationof the parameters. The results of these two models are alsocompared with those of the probit model.     

Oral nicotinamide riboside raises NAD+ and lowers biomarkers of neurodegenerative pathology in plasma extracellular vesicles enriched for neuronal origin

Declining nicotinamide adenine dinucleotide (NAD⁺) concentration in the brain during aging contributes to metabolic and cellular dysfunction and is implicated in the pathogenesis of aging-associated neurological disorders. Experimental therapies aimed at boosting brain NAD⁺ levels normalize several neurodegenerative phenotypes in animal models, motivating their clinical translation. Dietary intake of NAD⁺ precursors, such as nicotinamide riboside (NR), is a safe and effective avenue for augmenting NAD⁺ levels in peripheral tissues in humans, yet evidence supporting their ability to raise NAD⁺ levels in the brain or engage neurodegenerative disease pathways is lacking. Here, we studied biomarkers in plasma extracellular vesicles enriched for neuronal origin (NEVs) from 22 healthy older adults who participated in a randomized, placebo-controlled crossover trial (NCT02921659) of oral NR supplementation (500 mg, 2x /day, 6 weeks). We demonstrate that oral NR supplementation increases NAD⁺ levels in NEVs and decreases NEV levels of Aβ42, pJNK, and pERK1/2 (kinases involved in insulin resistance and neuroinflammatory pathways). In addition, changes in NAD(H) correlated with changes in canonical insulin–Akt signaling proteins and changes in pERK1/2 and pJNK. These findings support the ability of orally administered NR to augment neuronal NAD⁺ levels and modify biomarkers related to neurodegenerative pathology in humans. Furthermore, NEVs offer a new blood-based window into monitoring the physiologic response of NR in the brain.     

Nano-biotechnology in tumour and cancerous disease: A perspective review

In recent years, drug manufacturers and researchers have begun to consider the nanobiotechnology approach to improve the drug delivery system for tumour and cancer diseases. In this article, we review current strategies to improve tumour and cancer drug delivery, which mainly focuses on sustaining biocompatibility, biodistribution, and active targeting. The conventional therapy using cornerstone drugs such as fludarabine, cisplatin etoposide, and paclitaxel has its own challenges especially not being able to discriminate between tumour versus normal cells which eventually led to toxicity and side effects in the patients. In contrast to the conventional approach, nanoparticle-based drug delivery provides target-specific delivery and controlled release of the drug, which provides a better therapeutic window for treatment options by focusing on the eradication of diseased cells via active targeting and sparing normal cells via passive targeting. Additionally, treatment of tumours associated with the brain is hampered by the impermeability of the blood–brain barriers to the drugs, which eventually led to poor survival in the patients. Nanoparticle-based therapy offers superior delivery of drugs to the target by breaching the blood–brain barriers. Herein, we provide an overview of the properties of nanoparticles that are crucial for nanotechnology applications. We address the potential future applications of nanobiotechnology targeting specific or desired areas. In particular, the use of nanomaterials, biostructures, and drug delivery methods for the targeted treatment of tumours and cancer are explored.     

Proteolytic processing of the vitellogenin precursor in the boll weevil,Anthonomus grandis

The soluble proteins of the eggs of the coleopteran insect Anthonomus grandis Boheman, the cotton boll weevil, consist almost entirely of two vitellin types with M_rs of 160,000 and 47,000. We sequenced their N-terminal ends and one internal cyanogen bromide fragment of the large vitellin and compared these sequences with the deduced amino acid sequence from the vitellogenin gene. The results suggest that both the boll weevil vitellin proteins are products of the proteolytic cleavage of a single precursor protein. The smaller 47,000 M vitellin protein is derived from the N-terminal portion of the precursor adjacent to an 18 amino acid signal peptide. The cleavage site between the large and small vitellins at amino acid 362 is adjacent to a pentapeptide sequence containing two pairs of arginine residues. Comparison of the boll weevil sequences with limited known sequences from the single 180,000 M_r honey bee protein show that the honey bee vitellin N-terminal exhibits sequence homology to the N-terminal of the 47,000 M_r boll weevil vitellin. Treatment of the vitellins with an N-glycosidase results in a decrease in molecular weight of both proteins, from 47,000 to 39,000 and from 160,000 to 145,000, indicating that about 10–15% of the molecular weight of each vitellin consists of N-linked carbohydrate. The molecular weight of the deglycosylated large vitellin is smaller than that predicted from the gene sequence, indicating possible further proteolytic processing at the C-terminal of that protein. © 1993 Wiley-Liss, Inc.

1 This article is a US Government work and, as such, is in the public domain in the United States of America.