Chronobiologic Evaluation of Blood Pressure in School Children

Blood pressure (BP) and heart rate (HR) data were collected over 24 h with an ambulatory BP monitor to (a) determine the existence of 12-, 24-, and combined 12- and 24-h BP patterns in children as previously noted for adults; (b) provide MESOR (an acronym for midline estimating statistics of rhythm), amplitude, and acrophase data for subgroups of students by race and gender; and (c) determine the influence of HR (as an estimate of activity) on BP and BP patterns for 100 normal, healthy students 9-12 years of age. We found no statistically significant differences between various racial groups or between gender for MESOR, amplitude, acrophase, or degree of sinusoidality of circadian rhythmicity (R² values) for BP; clinically interesting differences were observed, including lower MESOR BPs in Hispanic males when compared with their female counterparts and slightly higher MESOR BPs in blacks of both genders when compared with whites. In addition, we demonstrated subgroups of students who exhibited specific 24-h and combined 12- and 24-h patterns. Also, 67% of subjects showed stable or nonrhythmic BP patterns, perhaps related to BP sampling intervals. Differences in HR, as a surrogate measure of activity, accounted for 56% of the variation in systolic BP but only 26% in diastolic BP over the 24 h.     

Intrinsic pKas of ionizable residues in proteins: An explicit solvent calculation for lysozyme

Molecular dynamics simulations of triclinic hen egg white lysozyme in aqueous solution were performed to calculate the intrinsic pK_as of 14 ionizable residues. An all-atom model was used for both solvent and solute, and a single 180 ps simulation in conjunction with a Gaussian fluctuation analysis method was used. An advantage of the Gaussian fluctuation method is that it only requires a single simulation of the system in a reference state to calculate all the pK_as in the protein, in contrast to multiple simulations for the free energy perturbation method. pK_int shifts with respect to reference titratable residues were evaluated and compared to results obtained using a finite difference Poisson-Boltzmann (FDPB) method with a continuum solvent model; overall agreement with the direction of the shifts was generally observed, though the magnitude of the shifts was typically larger with the explicit solvent model. The contribution of the first solvation shell to the total charging free energies of the titratable groups was explicitly evaluated and found to be significant. Dielectric shielding between pairs of titratable groups was examined and found to be smaller than expected. The effect of the approximations used to treat the long-range interactions on the pK_int shifts is discussed. © 1994 Wiley-Liss, Inc.     

Prior experience affects the visual ability ofRhagoletis pomonella flies (Diptera: Tephritidae) to find host fruit

Females of the apple maggot fly,Rhagoletis pomonella, were allowed for 3 days to alight upon and oviposit in green or red 18- to 20-mm hawthorn host fruit (Crategus mollis) or green or red 45- to 55-mm apple host fruit (Malus pumila) hung from branches of potted host trees in field enclosures. Subsequently, when females were released individually on potted host trees harboring fruit of one of these types, their ability to find fruit of unfamiliar size proved unaffected by prior experience with fruit but their ability to find fruit of unfamiliar color was significantly affected. Specifically, females exposed to red hawthorns or red apples were less able to find green hawthorns or green apples than were females experienced with either of the latter fruit types. Fruit odor was found to have no effect on female ability to find familiar compared with unfamiliar green fruit. In contrast, a difference in size (or surface chemistry) between familiar and unfamiliar fruit but not a difference in fruit color had a significant negative influence on the propensity of alighting females to bore into unfamiliar fruit. Three bouts of experience with alighting upon and ovipositing into fruit over a period of about 1 h had no detectable effect on female ability to find unfamiliar fruit but did reduce propensity to bore into unfamiliar fruit. Our findings are discussed in relation to insect ability to learn visual and chemical stimuli of resources and insect propensity to form host races. We also discuss the potential impact of our findings on nonpesticidal, behavioral methods of managingR. pomonella in commercial apple orchards.     

Non-lethal secondary product release from transformed root cultures of Beta vulgaris

Transformed root tissue of Beta vulgaris (Detroit Dark Red) was permeabilized to stimulate the release of intracellularly stored betanin without adverse affects on tissue viability as measured by biomass accumulation. Product release of up to 15% (w/w) was achieved by heat treatment at 42°C for 45 min with minimal effect on viability. Higher levels of product release were obtained with increasing temperature and exposure, but at the expense of viability. Viability was measured by comparing dry weight increases of permeabilized tissue 3 days after treatment vs non-permeabilized tissue over the same time interval. Recovery of heat-treated tissue was improved by addition of CaCl₂ (20 mm for 10 min) post-heat treatment. Betanin release up to 15% was also obtained at ambient temperature (25°C) by addition of up to 20 mm (NH₄)₂SO₄ in the presence of 1 mm ethylenediaminetetraacetic acid (EDTA). Correspondence to: A. A. DiIorio     

5′-Isothiocyanato-N-1-naphthylphthalamic acid: a chemically reactive site-directed irreversible ligand for phytotropin receptors

A chemically reactive analog of the phytotropin N-1-naphthylphthalamic acid (NPA) was synthesized and evaluated as a site-directed irreversible ligand for the NPA receptor. The NPA analog (5-isothiocyanato-N-1-naphthylphthalamic acid; NCS-NPA) was synthesized in two steps. Pretreatment of etiolated Helianthus hypocotyl segments with NCS-NPA at concentrations in excess of 1 M resulted in a dose-dependent inhibition of basipetal [¹⁴C]IAA transport. Net uptake of IAA by hypocotyl segments was stimulated by NCS-NPA at concentrations of 1 M or greater. NCS-NPA inhibited the saturable binding of [³H]NPA in Helianthus microsomes in a dose-dependent fashion with 50% inhibition occurring at NCS-NPA concentrations of 3 to 10 nM. The binding affinity of [³H]NPA in microsomes pretreated with NCS-NPA followed by extensive washing was substantially reduced. These results demonstrate that NCS-NPA is a site-directed irreversible ligand for the NPA receptor and suggest that it may be of use in the purification and characterization of this biologically important receptor.Abbreviations ANPA 5-amino-naphthylphthalamic acid - IAA indole-3-acetic acid - NCS-NPA 5-isothiocyanato-N-1-naphthylphthalamic acid - NPA N-1-naphthylphthalamic acid - TLC thin-layer chromatography     

31P NMR Relaxation Does Not Affect the Quantitation of Changes in Phosphocreatine, Inorganic Phosphate, and ATP Measured In Vivo During Complete Ischemia in Swine Brain

Abstract: Ischemia-induced changes in ³¹P NMR relaxation were examined in 16 piglets. NMR spectra were acquired under control conditions and during complete cerebral ischemia induced via cardiac arrest. Changes in T ₁ were assessed directly in six animals during control conditions and after 30–45 min of complete ischemia when changes in brain P₁ levels had reached a plateau. The T ₁ for P₁ did not change, i.e., 2.3 ± 0.5 s during control conditions versus 2.4 ± 1.0 s during ischemia. To evaluate phosphocreatine and ATP, two types of spectra, with a long (25-s) or short (1-s) interpulse delay time, were collected during the first 10 min of ischemia (n = 10). Both types of spectra showed the same time course of changes in phosphocreatine and ATP levels, implying that the T ₁ relaxation times do not change during ischemia. There were no changes in the linewidths of phosphocreatine, ATP, or P₁ during ischemia, implying that the T *₂ values remain constant. Our results suggest that the ³¹P T ₁ and T *₂ for phosphocreatine, P_i, and ATP do not change during ischemia, and therefore changes in ³¹P NMR peak intensity accurately reflect changes in metabolite concentrations.     

Cerebral Metabolic Compartmentation as Revealed by Nuclear Magnetic Resonance Analysis of D-[1-13C]Glucose Metabolism

Abstract: Nuclear magnetic resonance (NMR) was used to study the metabolic pathways involved in the conversion of glucose to glutamate, γ-aminobutyrate (GABA), glutamine, and aspartate. d -[1^-13C]Glucose was administered to rats intraperitoneally, and 6, 15, 30, or 45 min later the rats were killed and extracts from the forebrain were prepared for ¹³C-NMR analysis and amino acid analysis. The absolute amount of ¹³C present within each carbon-atom pool was determined for C-2, C-3, and C-4 of glutamate, glutamine, and GABA, for C-2 and C-3 of aspartate, and for C-3 of lactate. The natural abundance ¹³C present in extracts from control rats was also determined for each of these compounds and for N-acetylaspartate and taurine. The pattern of labeling within glutamate and GABA indicates that these amino acids were synthesized primarily within compartments in which glucose was metabolized to pyruvate, followed by decarboxylation to acetyl-CoA for entry into the tricarboxylic acid cycle. In contrast, the labeling pattern for glutamine and aspartate indicates that appreciable amounts of these amino acids were synthesized within a compartment in which glucose was metabolized to pyruvate, followed by carboxylation to oxaloacetate. These results are consistent with the concept that pyruvate carboxylase and glutamine synthetase are glia-specific enzymes, and that this partially accounts for the unusual metabolic compartmentation in CNS tissues. The results of our study also support the concept that there are several pools of glutamate, with different metabolic turnover rates. Our results also are consistent with the concept that glutamine and/or a tricarboxylic acid cycle intermediate is supplied by astrocytes to neurons for replenishing the neurotransmitter pool of GABA. However, a similar role for astrocytes in replenishing the transmitter pool of glutamate was not substantiated, possibly due to difficulties in quantitating satellite peaks arising from ¹³C-¹³C coupling.     

Pitfalls in the molecular genetic diagnosis of Leber hereditary optic neuropathy (LHON).

Pathogenetic mutations in mtDNA are found in the majority of patients with Leber hereditary optic neuropathy (LHON), and molecular genetic techniques to detect them are important for the diagnosis. A false-positive molecular genetic error has adverse consequences for the diagnosis of this maternally inherited disease. We found a number of mtDNA polymorphisms that occur adjacent to known LHON-associated mutations and that confound their molecular genetic detection. These transition mutations occur at mtDNA nt 11779 (SfaNI site loss, 11778 mutation), nt 3459 (BsaHI site loss, 3460 mutation), nt 15258 (AccI site loss, 15257 mutation), nt 14485 (mismatch primer Sau3AI site loss, 14484 mutation), and nt 13707 (BstNI site loss, 13708 mutation). Molecular genetic detection of the most common pathogenetic mtDNA mutations in LHON, using a single restriction enzyme, may be confounded by adjacent polymorphisms that occur with a false-positive rate of 2%-7%.