Safety and efficacy of oral anticoagulants in extreme weights

BACKGROUND

The 2021 International Society on Thrombosis and Haemostasis' (ISTH) recommends standard doses of apixaban and rivaroxaban regardless of high body mass index (BMI) and weight, but had not compare DOACs head-to-head in obesity or address underweight patients.

METHODS

Our aim is to evaluate the safety and efficacy of DOACs in underweight and obese patients compared to warfarin. The primary endpoints include incidence of thromboembolic and bleeding events. Descriptive statistics was used for continuous variables. The Kruskal-Wallis test was used to compare the four-groups for continuous measures and the chi-square test or Fisher's exact test was used to analyze categorical data. The chi-square test or Fisher's exact test, was used for categorical variables, and the Mann-Whitney test (the non-parametric counterpart to the two-sample t-test) for continuous data.

RESULTS

Of 2940 patients receiving anticoagulation for venous thromboembolism (VTE) treatment or atrial fibrillation (AF), 492 met eligibility criteria. Within each group, 248 patients received warfarin, 101 received apixaban, 100 received rivaroxaban and 43 received dabigatran. Patients were characterized in 4 body mass index (BMI) categories, in which 80 were underweight and 412 were obese.

CONCLUSIONS

When each DOAC was compared to warfarin in rates of VTE, apixaban showed statistically significant lower rate of VTE (p = 0.0149). However, no statistical significance was identified in the rate of VTE between DOACs combined vs. warfarin (p = 0.1529). When each DOAC was compared to warfarin, apixaban showed the lowest rate of overall bleeding (p = 0.0194). However, no statistical difference in the rate of bleeding was observed between DOACs combined vs. warfarin (p = 0.3284). Patients with extreme body weights requiring anticoagulation for VTE and AF may safety benefit from DOAC therapy. This evaluation showed apixaban with the lowest rate of VTE and bleeding compared to warfarin, rivaroxaban, and dabigatran. These results provide experience for the clinician to use DOACs, particularly apixaban, in underweight and obese populations.

Measuring quality of care in the treatment of colorectal cancer: the moffitt quality practice initiative

PURPOSE

The Moffitt Quality Practice Initiative (MQPI) is a practice-based system of quality self-assessment, the ultimate goal of which is to improve the quality of cancer care at a statewide level. The initial phase of this project focused on developing procedures, determining feasibility, and evaluating utility for assessing quality of care for colorectal cancer within an existing affiliate network.

PATIENTS AND METHODS

Representatives from four oncology groups selected quality measures consistent with evidence-, consensus-, and safety-based guidelines that could be abstracted from medical records. Trained abstractors then reviewed records of all eligible colorectal patients seen by each practice in 2004. Frequencies of responses for each indicator were tabulated for overall and practice-specific level of adherence and were compared among practices.

RESULTS

Adherence was uniformly high for several indicators, including confirmatory pathology report, staging information, and chemotherapy discussion or recommendation. Lower adherence was evident across practices for performance of carcinoembryonic tests and complete colonoscopic evaluations. Significant variation among practices was evident only for consent for chemotherapy.

CONCLUSION

The initial phase of MQPI demonstrated the feasibility and utility of assessing quality indicators for colorectal cancer among members of an existing affiliate network. Findings identified areas where adherence to care was uniformly high, but also identified areas where both overall and practice-specific adherence were less than optimal. These efforts lay the groundwork for expanding MQPI in several directions that have in common the potential to improve the quality of cancer care on a statewide basis.

The sequence of the human genome

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

A novel fluorescent coronenyl-phospholipid analogue for investigations of submicrosecond lipid fluctuations

A fluorescent phospholipid derivative, the 2'-(4-coronenylbutyric) ester of lyso-egg phosphatidylcholine, has been synthesized for use in studies of submicrosecond lipid dynamics. Synthesis of the phospholipid derivative involves Friedel-Crafts acylation of free coronene, followed by a Huang-Minlon reduction to yield the fatty-acyl derivative, 4-coronenylbutyric acid. Esterification of the carboxylic acid with lyso-phosphatidylcholine is achieved through a mixed anhydride intermediate. The resultant coronenyl-phospholipid adduct (Cor-PC) has been incorporated into sonicated unilamellar vesicles of dimyristoylphosphatidylcholine (DMPC) for dynamic lipid studies. Fluorescence quenching studies using potassium iodide, together with steady-state emission anisotropy (EA) measurements, confirm that the coronene moiety of the phospholipid adduct resides towards the head group interfacial region of the lipid bilayer. Unique properties of this new fluorescent phospholipid adduct are its long mean fluorescence lifetime (tau av approximately 112 ns at 14 degrees C), the planar symmetry of the fluorophore and its defined bilayer location. As a consequence, depolarizing motions of the coronene moiety target submicrosecond 'gel-fluid' lipid dynamics arising from a relatively narrow bilayer distribution. Our data suggest that the sensitivity of this new long-lived fluorescent phospholipid analogue to localized transverse submicrosecond lipid dynamics can provide important biological insights into varied processes including lipid-peptide interactions, bilayer fluidity gradients and passive ion transport.

Probing the binding domain of the Saccharomyces cerevisiae alpha-mating factor receptor with rluorescent ligands

Three analogues of the alpha-mating factor pheromone of Saccharomyces cerevisiae containing the 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD) group were synthesized that had high binding affinity to the receptor and retained biological activity. The fluorescence emission maximum of the NBD group in [K7(NBD),Nle(12)]-alpha-factor was blue shifted by 35 nm compared to buffer when the pheromone bound to its receptor. Fluorescence quenching experiments revealed that the NBD group in [K7(NBD),Nle(12)]-alpha-factor bound to the receptor was shielded from collision with iodide anion when in aqueous buffer. In contrast, the emission maximum of NBD in [K7(ahNBD),Nle(12)]-alpha-factor or [Orn7(NBD),Nle(12)]-alpha-factor was not significantly shifted and iodide anion efficiently quenched the fluorescence of these derivatives when they were bound to receptor. The fluorescence investigation suggests that when the alpha-factor is bound to its receptor, K7 resides in an environment that has both hydrophobic and hydrophilic groups within a few angstroms of each other.

Two new early bacteriophage T4 genes, repEA and repEB, that are important for DNA replication initiated from origin E

Two new, small, early bacteriophage T4 genes, repEA and repEB, located within the origin E (oriE) region of T4 DNA replication, affect functioning of this origin. An important and unusual property of the oriE region is that it is transcribed at early and late periods after infection, but in opposite directions (from complementary DNA strands). The early transcripts are mRNAs for RepEA and RepEB proteins, and they can serve as primers for leading-strand DNA synthesis. The late transcripts, which are genuine antisense RNAs for the early transcripts, direct synthesis of virion components. Because the T4 genome contains several origins, and because recombination can bypass a primase requirement for retrograde synthesis, neither defects in a single origin nor primase deficiencies are lethal in T4 (Mosig et al., FEMS Microbiol. Rev. 17:83-98, 1995). Therefore, repEA and repEB were expected and found to be important for T4 DNA replication only when activities of other origins were reduced. To investigate the in vivo roles of the two repE genes, we constructed nonsense mutations in each of them and combined them with the motA mutation sip1 that greatly reduces initiation from other origins. As expected, T4 DNA synthesis and progeny production were severely reduced in the double mutants as compared with the single motA mutant, but early transcription of oriE was reduced neither in the motA nor in the repE mutants. Moreover, residual DNA replication and growth of the double mutants were different at different temperatures, suggesting different functions for repEA and repEB. We surmise that the different structures and protein requirements for functioning of the different origins enhance the flexibility of T4 to adapt to varied growth conditions, and we expect that different origins in other organisms with multiorigin chromosomes might differ in structure and function for similar reasons.

A direct method for the correction of pressure-induced scrambling of polarized fluorescence intensities

A simple and direct method for the simultaneous correction of steady-state polarized fluorescence intensities, depolarized (or scrambled) by the effects of applied hydrostatic pressure, is described. In the method discussed here, it is not necessary to first determine the scrambling factors from a separate experiment with a dye immobilized in a rigid medium. Rather correction for depolarizing effects of the high-pressure spectroscopy cell windows is achieved by direct recalculation of the measured polarized data obtained for the sample of interest at the time of data collection. This method of correction is tested for common fluorescent dyes 1, 6-diphenyl-1,3,5-hexatriene (DPH) and 9,10-diphenylanthracene in glycerol where their rotational behavior is well understood. In addition, the pressure-induced "melt" profile for the more complicated biologically relevant system of DPH imbedded within dipalmitoylphosphatidylcholine small unilamellar vesicles has been reexamined. While the method discussed here is used for the correction of steady-state polarized data, it may be easily adapted for use in time-resolved polarized fluorescence measurements. Advantages and limitations of the new correction method are discussed.

The largest (70 kDa) product of the bacteriophage T4 DNA terminase gene 17 binds to single-stranded DNA segments and digests them towards junctions with double-stranded DNA

Bacteriophage terminases are oligomeric multifunctional proteins that bind to vegetative DNA, cut it and, together with portal proteins, translocate the DNA into preformed heads. Most terminases are encoded by two partially overlapping genes. In phage T4 they are genes 16 and 17. We have shown before that the larger of these, gene 17, can yield, in addition to a full-length 70 kDa product, several shorter peptides. At least two of these, gene product (gp) 17' and gp17", are initiated in the same reading frame as the 70 kDa gp17 from internal ribosome binding sites. Most of the shorter gp17 s contain predicted ATPase motifs, but only the largest (70 kDa) peptide has a predicted single-stranded DNA binding domain. Here we describe the DNA binding and cutting properties of the purified 70 kDa protein, expressed from two different clones containing gene 17 but no other T4 gene. Epitope-specific antibodies, which recognize several different gene 17 products in extracts of induced clones or of T4-infected cells, precipitate the purified 70 kDa gp17. When Mg2+ is chelated by EDTA this 70 kDa protein binds to single-stranded DNA, preferentially to junctions of single- and double-stranded DNA segments. It does not bind to blunt-ended double-stranded DNA. When Mg2+ is present the purified 70 kDa gp17 digests single-stranded segments preferentially up to junctions with double-stranded DNA. A 70 kDa gp17 from a P379L temperature sensitive (ts) mutant, which has lost the nuclease and ATPase activities, retains the single-stranded DNA binding activity. Taken together with earlier findings these results support a model for packaging of T4 DNA from single-stranded regions in recombinational or replicative intermediates, which occur at nearly random positions of the genome. This mechanism may be an alternative to site-specific initiation of packaging proposed by other investigators.

A novel mechanism of virus-virus interactions: bacteriophage P2 Tin protein inhibits phage T4 DNA synthesis by poisoning the T4 single-stranded DNA binding protein, gp32

P2 prophages have been known to inhibit DNA replication and growth of T-even phages. We show here that this inhibition is due to poisoning of the T-even single-stranded DNA binding protein gp32 by the product of the nonessential P2 tin gene. Synthesis of Tin protein from a gene cloned in a multicopy plasmid is necessary and sufficient to completely prevent de novo DNA replication and growth of wild-type T2 or T4 phage. We isolated more than 20 independent mutants that render T-even phages resistant to poisoning by the P2 Tin protein. In all of these mutants, which we call asp, Asp codon 163 of gene 32 is changed to a Gly or Asn codon. The mutant alleles are recessive; i.e., when wild-type and asp mutants coinfect the same host cells, most DNA replication is poisoned by P2 Tin protein. To explain our results, we propose that the P2 Tin protein interacts with T-even gp32 at position 163 and distorts the helical filament of gene 32 protein on single-stranded DNA. Thereby Tin protein inhibits either assembly or function, or both, of the T4 replisome. The inhibition of late gene expression by P2 Tin protein may be an indirect consequence of inhibition of DNA replication.

Submicrosecond phospholipid dynamics using a long-lived fluorescence emission anisotropy probe

The use of the long-lived fluorescence probe coronene (mean value of tau(FL) approximately 200 ns) is described for investigating submicrosecond lipid dynamics in DPPC model bilayer systems occurring below the lipid phase transition. Time-resolved fluorescence emission anisotropy decay profiles, measures as a function of increasing temperature toward the lipid-phase transition temperature (T(C)), for coronene-labeled DPPC small unilamellar vesicles (SUVs), are best described in most cases by three rotational decay components (phi(i = 3)). We have interpreted these data using two dynamic lipid bilayer models. In the first, a compartmental model, the long correlation time (phi(N)) is assigned to immobilized coronene molecules located in "gel-like" or highly ordered lipid phases (S-->1) of the bilayer, whereas a second fast rotational time (phi(F) approximately 2-5 ns) is associated with probes residing in more "fluid-like" regions (with corresponding lower ordering, S-->0). Interests here have focused on the origins of an intermediate correlation time (50-100 ns), the associated amplitude (beta(G)) of which increases with increasing temperature. Such behavior suggests a changing rotational environment surrounding the coronene molecules, arising from fluidization of gel lipid. The observed effective correlation time (phi(EFF)) thus reflects a discrete gel-fluid lipid exchange rate (k(FG)). A refinement of the compartmental model invokes a distribution of gel-fluid exchange rates (d(S,T)) corresponding to a distribution of lipid order parameters and is based on an adapted Landau expression for describing "gated" packing fluctuations. A total of seven parameters (five thermodynamic quantities, defined by the free energy versus temperature expansion; one gating parameter (gamma) defining a cooperative "melting" requirement; one limiting diffusion rate (or frequency factor: d(infinity))) suffice to predict complete anisotropy decay curves measured for coronene at several temperatures below the phospholipid T(C). The thermodynamic quantities are associated with the particular lipid of interest (in this case DPPC) and have been determined previously from ultrasound studies, thus representing fixed constants. Hence resolved variables are r(O), temperature-dependent gate parameters (gamma), and limiting diffusion rates (d(infinity)). This alternative distribution model is attractive because it provides a general probe-independent expression for distributed lipid fluctuation-induced probe rotational rates occurring within bilayer membranes below the phospholipid phase transition on the submicrosecond time scale.

The Indented Paragraph Reading Test in the assessment of left hemi-neglect

We investigated the validity of the Indented Paragraph Reading Test (IPRT), designed to assess left hemi-neglect (LHN) in reading behavior, with regard to education effects, scoring properties, and sensitivity to recovery of LHN. The IPRT was administered aspart of a larger battery to 50 right-hemisphere stroke patients approximately 1, 2, 3, and 7 months post-stroke if, and only if, the patient demonstrated LHN on the previous test battery. Contrary to expectations, performance on the IPRT was not correlated with education and even patients with minimal formal education were able to complete the test. We demonstrated that the author's suggested scoring criterion was valid and sensitive to the presence of LHN as well as to its recovery over time.

Alterations in brain phosphorus metabolite concentrations associated with areas of high signal intensity in white matter at MR imaging

Areas of high signal intensity in white matter are identified on brain magnetic resonance (MR) imaging studies in 25%-50% of elderly subjects. The authors used phosphorus-31 MR spectroscopy to characterize the metabolic status of hemispheric white matter brain volumes in 30 elderly subjects with white matter areas of high signal intensity at MR imaging. Compared with white matter volumes with no or minimal areas of high intensity, white matter volumes with extensive areas of high intensity evidenced a 26% decrease in the adenosine triphosphate (ATP)/inorganic phosphate (Pi) ratio (P = .03) and a 21% decrease in the ATP concentration (P = .05), with the Pi level unchanged. A pilot P-31 spectroscopic imaging study in a subject with a large, coalescing white matter area of high signal intensity demonstrated large reductions in metabolite concentrations in the high-signal-intensity area. These results suggest that extensive white matter areas of high signal intensity indicate a process that affects white matter cellular energy metabolism.

Cognitive impairments in abstinent alcoholics

Impaired cognitive functioning in alcoholics is widespread during the first months of detoxification. Between half and two thirds of abstinent alcoholics exhibit cognitive impairments during this period, with residual deficits persisting for years after detoxification in some patients. The most severe deficits have been observed in visuospatial abilities, perceptual-motor integration, abstract reasoning, and new learning. The most significant predictors of cognitive dysfunction in persons recovering from alcoholism are the time elapsed since the last drink and the person's age. Surprisingly, the pattern and duration of a patient's alcohol abuse are relatively weak determinants of neuropsychological impairment during abstinence. Research investigating the hypothesis that cognitive impairments may be related to alcoholic persons resuming drinking has yielded mixed results, but a higher level of neuropsychological functioning is associated with increased rates of completing treatment programs and with greater success in the work environment after discharge from treatment. The possibility of cognitive limitations should be taken into account in planning treatment programs for alcoholism.

Preservation of normal cognitive functioning in elderly subjects with extensive white-matter lesions of long duration

Although deep white-matter brain lesions are seen on magnetic resonance imaging in about one third of elderly subjects, their clinical significance is not known. In 1984, we studied three retired teachers who had extensive deep white-matter brain lesions on magnetic resonance imaging, yet functioned cognitively at an above-average level. Blinded review of 1981 computed tomographic scans revealed patchy white-matter lucencies for two of the subjects. Repeated magnetic resonance imaging in 1987 showed that the deep white-matter brain lesions were at least as extensive as in the initial study. One subject had developed renal failure, while the other two continued to function at a high level with no evidence of cognitive decline or psychiatric or neurologic impairment. The presence of extensive deep white-matter brain lesions for up to 7 years in two subjects whose cognitive, behavioral, and neurologic functioning is unimpaired suggests that deep white-matter brain lesions do not necessarily indicate a clinically significant central nervous system disease process.

A fifteen-item modification of the Fuld Object-Memory Evaluation: preliminary data from healthy middle-aged adults

A modification of the Fuld Object-Memory Evaluation (FOME) test was developed for use with middle-aged adults. To avoid the ceiling effect which occurs when the 10-item FOME is used with adults in this age group, we made the test more difficult by increasing the number of items to 15. We obtained preliminary data on the 15-item version of the test by administering it to 32 healthy, well-educated adults aged 35 to 55. This version of the test was difficult enough so that even high functioning adults needed multiple trials to memorize all items. No sex differences, and no significant correlations with education or age for any aspect of test performance were found. We present mean scores for recall on each trial, as well as averaged scores for storage, retrieval, consistent retrieval, and recall failure across five trials.

Narrative speech deficits in dyslexics

Narrative speech of 31 dyslexics and 33 good readers was studied. Subjects were 10- to 12-year-old right-handed boys of normal intelligence, and with normal neurological status, vision, and hearing. The dyslexics used shorter communication units (independent clauses with all their modifiers), and a higher percentage of their words were noncommunications (words which are extraneous to the speaker's intended meaning). Rate of speech was the same in both groups. These findings were replicated in an independent second cohort of 21 dyslexics and 21 controls, aged 9 to 13. Our findings support theories of a general language deficit in dyslexia, and demonstrate the involvement of the previously unexamined area of narrative speech.

Neurometrics does not detect 'pure' dyslexics

Thirty-eight severely dyslexic boys and 38 good readers were evaluated with neurometrics, a diagnostic procedure based on the application of numerical taxonomy to EEG spectra obtained during resting conditions, supplemented by selected evoked potential features. This procedure generates deviance scores for the EEG spectra by comparing each individual's values to those obtained from a normative population and has been reported to discriminate learning disabled children from normal controls (Ahn et al. 1980). In the present study, all subjects, dyslexic and control, passed stringent screening to assure normal intellectual, neurological, sensory and emotional status. The false positive rate obtained in our control group was comparable to that reported earlier. However, none of the deviance scores significantly discriminated dyslexics from controls; most subjects from both groups were classified as normal. Severe dyslexia per se is thus not associated with the specific neurometric abnormalities reported previously in more heterogeneous learning disabled populations.

Anisotropy decay associated fluorescence spectra and analysis of rotational heterogeneity. 2. 1,6-Diphenyl-1,3,5-hexatriene in lipid bilayers

The application of a new spectroscopic tool [Knutson, J. R., Davenport, L., & Brand, L. (1986) Biochemistry (preceding paper in this issue)] for studying rotational microheterogeneity of probe location in lipid bilayer systems is described. Anisotropy decay associated spectra are derived from experimentally obtained polarized emission components. "Early" difference spectra (IV - IH) contain contributions from both fast and slow rotors, while "late" difference spectra predominantly reflect the emission from slowly rotating fluorophores. Anisotropy decay associated spectra have been used to resolve the emission spectra of 1,6-diphenyl-1,3,5-hexatriene (DPH) imbedded within a known rotationally heterogeneous mixture of two vesicle types (L-alpha-dimyristoyllecithin and L-alpha-dipalmitoyllecithin). At 29 degrees C, diphenylhexatriene within pure dimyristoyllecithin vesicles rotates rapidly, with a small r infinity, while diphenylhexatriene in dipalmitoyllecithin vesicles exhibits a large r infinity. Spectra for diphenylhexatriene imbedded in the two vesicle types show small but significant spectral differences. A spectrum of a mixture of the two vesicle types with DPH lies between these characteristic component spectra. The spectrum extracted for "immobilized" probes in the mixture correctly overlays the dipalmitoyllecithin spectrum. Further studies have shown that diphenylhexatriene exhibits more than one emission anisotropy decay associated spectrum in vesicles of a single lipid type, when that lipid is near its phase transition temperature. Diphenylhexatriene apparently inhabits more than one rotational environment even in these "homogeneous" vesicle preparations.

Anisotropy decay associated fluorescence spectra and analysis of rotational heterogeneity. 1. Theory and applications

Individual fluorescence spectra for species in a heterogeneous system can be determined by using differences between the rotational correlation times of those components. Each spectrum derived is associated with a particular fluorescence anisotropy decay function; hence, they are anisotropy decay associated spectra (ADAS). We have previously shown [Knutson, J. R., Walbridge, D. G., & Brand, L. (1982) Biochemistry 21, 4671-4679] that a system containing different decay functions for total intensity can be resolved into constituent decay-associated spectra. ADAS extends the technique into the realm of fluorescence polarization, making use of the often disparate Brownian rotations found in heterogeneous biochemical systems. In this paper, we present the basic theory for ADAS in various heterogeneous systems and then present an example of ADAS resolving a binary mixture of macromolecules into "fast-rotor" (smaller or more mobile) and "slow-rotor" (larger or less mobile) components. They correctly superimpose spectra taken for the unmixed components. In the companion paper [Davenport, L., Knutson, J. R., & Brand, L. (1986) Biochemistry (following paper in this issue)], a specific application to a problem of importance of lipid biochemistry--e.g., the origin of the membrane probe order parameter in lipid bilayers--is presented, demonstrating the role rotational heterogeneity may play in biochemical fluorescence.

Excited-state proton transfer of equilenin and dihydroequilenin: interaction with bilayer vesicles

The two-state excited-state proton-transfer process for d-equilenin [d-3-hydroxyestra-1,3,-5(10),6,8-pentaen-17-one] and dihydroequilenin is found to depend both on pH and on proton acceptor concentration. Both the protonated and deprotonated forms of the excited molecule are fluorescent. As is the case for 2-naphthol, the excited-state pKa (pKa*) is substantially lower than the ground-state pKa. Fluorescence decay studies have been performed as a function of emission wavelength in aqueous solutions at pH 6.9 in the presence of acetate anion (0.1 M). At this pH, both back-reaction from the excited-state and ground-state heterogeneity are minimal. A monoexponential decay is found in the blue region of the spectrum and a biexponential decay on the red edge. The lifetimes measured across both regions are constant, with a negative preexponential term, characteristic of an excited-state reaction, evident at longer wavelengths. Decay-associated spectra (DAS), the preexponential terms associated with the measured lifetimes, have been acquired for these aqueous solutions. Equilenin and dihydroequilenin are found to adsorb to dimyristoyllecithin (DML) vesicles. Rates for excited-state proton transfer are greatly reduced when dihydroequilenin adsorbs to vesicles. The accessibility of the bound probe to acetate as a proton acceptor depends on the cholesterol content of the vesicles.

EEG spectra in dyslexic and control boys during resting conditions

We studied the resting eyes open and eyes closed EEG in carefully screened samples of 9-13-year-old dyslexic and control boys within a 2-cohort cross-validation design with repeat testing 1-3 years later. We found: no difference between groups in delta or theta activity in either cohort or in repeat testing 1-3 years later; in the dyslexics, decreased beta (19-24 c/sec) activity at bilateral central, parietal and mid-temporal leads referenced to vertex; inconsistent group differences in the alpha band: the first cohort dyslexics had lower alpha power than did the controls, but there was no group difference in the second cohort; and significant relative delta differences between groups in the first cohort, which were shown to be a statistical artifact of the use of relative power. We conclude that: dyslexia per se is not associated with increased absolute power in the delta and theta bands; lower power in the high beta band is reliably found in these samples of dyslexics without other disorders; and alpha power levels are not consistently lower in the dyslexic group.

Transverse location of the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene in model lipid bilayer membrane systems by resonance excitation energy transfer

A fluorescent phospholipid derivative, the fluoresceinthiocarbamyl adduct of a natural phosphatidylethanolamine, has been synthesized and incorporated into sonicated single-bilayer vesicles of egg lecithin and dipalmitoyllecithin. The surface location of this probe has been confirmed by using extrinsic fluorescence quenching studies together with steady-state emission anisotropy measurements. Electronic excitation energy transfer between 1,6-diphenyl-1,3,5-hexatriene incorporated within the hydrophobic core of the bilayer and the novel derivative has been investigated to estimate the depth within the bilayer at which the former is located. Efficiencies have been measured for two different phospholipids, egg lecithin and dipalmitoyllecithin, in the latter case both above and below the phospholipid phase transition, with and without added cholesterol. The observed dependence of the transfer efficiency on the acceptor concentration was compared with that calculated according to Förster theory applied to random two-dimensional distributions of donor and acceptor molecules in parallel planes for various interplanar separations, taking into account orientational effects. The Förster R0 of about 45 A for this donor-acceptor pair is particularly well suited to such studies since it is of the order of the width of the bilayer. The experiments showed that energy-transfer spectroscopy can provide useful quantitative information as to the transverse location of diphenylhexatriene in homogeneous phospholipid bilayers and may also reflect lateral partitioning of donor or of both donor and acceptor into different phases in systems exhibiting phase separations.

MR imaging of the aging brain: patchy white-matter lesions and dementia

Magnetic resonance (MR) imaging studies of the brain in five elderly patients with non-Alzheimer dementia were compared with those in two groups of nondemented control subjects. Group 1 included five subjects aged 59-66; group 2 included nine subjects aged 74-81. In all of the demented patients and in three of the subjects in the older control group, MR showed diffuse, patchy white-matter lesions. A rating scale was used to grade the severity of the changes. The results suggest a higher incidence of white-matter lesions in elderly patients with non-Alzheimer dementia and in cognitively normal elderly with advancing age.

FANTASTIC Lifestyle Survey of University of Waterloo Employees

The purpose of this study was to survey selected health behaviors of University of Waterloo employees. The FANTASTIC lifestyle questionnaire was distributed to all employees. Results indicate that, overall, the university's employees' health behaviors are good. However, there is room for improvement in the areas of physical activity, tobacco use, insight and career, particularly for the women surveyed. The data from the study will be used to direct the university's Campus Health Promotion program planning.

Nanosecond time-resolved emission anisotropy of the fluorescent probe 1,6-diphenyl-1,3,5-hexatriene in human amniotic fluid

The fluorescence emission anisotropy of 1,6-diphenyl-1,3,5-hexatriene in human amniotic fluid has been studied using nanosecond time-resolved emission techniques. These studies demonstrate that the previously reported decrease in the steady state emission anisotropy, [r], with gestational age is due to a change in the rate of rotational motion of the probe. The emission anisotropy decays to a limiting value (r infinity) greater than zero, suggesting a hindered rotation of the probe, and this is independent of gestational age. The decay function for the emission anisotropy of amniotic fluids from 17, 29, 40 and 41 weeks in gestational age can be best expressed as a single exponential plus a constant term, with rotational correlation times varying from 17 ns to 2.2 ns, respectively. The zero time emission anisotropy remains approx. 0.30 for both early and late gestational times.

Comparison of human and hamster mitochondrial transfer RNA. Physical properties and methylation status

We have compared mitochondrial transfer RNA from cultured human (HeLa) and hamster(BHK) cells, giving emphasis to distinctive properties previously noted for the BHK system. Both HeLa and BHK mitochondrial tRNA sedimented slower, and had lower mobilities in "warm" acrylamide gels, than their cytoplasmic counterparts, suggesting that both mitochondrial tRNA populations have unusually loose configurations. HeLa mitochondrial tRNA was found to contain 2.8 methyl groups per 100 nucleotides compared to 8.7 for cytoplasmic, figures similar to previous BHK results. Both mitochondrial tRNA populations were notably deficient in 7-methylguanine, methylribose, and methylated pyrimidines. We propose that mitochondrial tRNA (or perhaps animal mitochondrial tRNA) constitutes a distinct evolutionary class.