Transcutaneous optical telemetry system for an implantable electrical ventricular heart assist device.
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Heart-Assist Devices↗
Biomedical subjects
F Johnson
Publications and source records attributed to F Johnson.
Lipreading in patients with schizophrenia.
This study was designed to explore whether schizophrenic patients who are able to maintain their gaze with adequate persistence could competently lip-read. Four lipreading tests, designed to assess recognition of syllables, words, and overlearned sentences, were administered to 15 schizophrenic and 15 normal subjects matched for age, sex, and educational level. The patients proved to be competent lip-readers susceptible to the blend illusion and were inferior only in lipreading of overlearned sentences. The latter difficulty may tentatively be attributed to the inadequacy of the patient's premorbid social network for establishing contextual cues that aid in the recognition of overlearned sentences.
Adult↗
Acute toxic delirium in a patient using transdermal fentanyl.
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Acute Disease↗
Local distribution and dosimetry of 226Ra in the trabecular skeleton of the beagle.
Young adult beagle dogs received a single injection of 38.1 kBq/kg body wt 226Ra and were serially sacrificed at 4 to 2955 days postinjection. Samples of sites of trabecular bone in the lumbar vertebral body, proximal ulna, and distal femoral metaphysis and epiphysis were analyzed autoradiographically. The time-dependent changes in the average 226Ra concentrations in the four regions were analyzed in terms of a compartmental model. The clearance rate from the lumbar vertebral body was about four times more rapid than for the proximal ulna and distal femoral epiphysis. Ratios of hotspot to diffuse label concentrations varied from about 10 to 23. The dose rate to the endosteum ranged between 8.7 and 39.5 mGy/day initially and 4 and 10.5 mGy/day toward the end of the observation period. Mean marrow dose rates were lower by a factor of 3 to 9.5. During their residence time the nuclei of bone lining cells receive a maximum dose of 8 Gy in the proximal ulna (2955 days after injection) and a minimum dose of 0.63 Gy in the lumbar vertebra (2955 days after injection). This corresponds on the average to 17 and 1.4 alpha-particle hits to the cell nuclei, respectively.
Animals↗
Inhibition of cellular thymidylate synthesis by cytotoxic propenal derivatives of pyrimidine bases and deoxynucleosides.
A series of cytotoxic propenal (3-oxoprop-1-enyl) derivatives of pyrimidine bases and deoxynucleosides was evaluated for their ability to block thymidylate synthesis in intact and permeabilized murine leukemia L1210 cells. Several were potent inhibitors of this process, likely contributing to their cytotoxicity. The IC50 values of thymidine-3-propenal, the prototype of this series, in intact and permeabilized L1210, L-M and L-M(TK-) cells were 21, 7.5, and 75 microM and 1.5, 1.7, and 3.5 microM, respectively. The related base analogue, thymine-1-propenal, is a product of bleomycin-induced DNA strand-scission; the results of the present study bear on the mode of action of this antibiotic.
Acrolein↗
Structural features of an exocyclic adduct positioned opposite an abasic site in a DNA duplex.
Structural studies have been extended to dual lesions where an exocyclic adduct is positioned opposite an abasic site in the center of a DNA oligomer duplex. NMR and energy minimization studies were performed on the 1,N2-propanodeoxyguanosine exocyclic adduct (X) positioned opposite a tetrahydrofuran abasic site (F) with the dual lesions located in the center of the (C1-A2-T3-G4-X5-G6-T7-A8-C9).(G10-T11-A12-C-13-F14-C15 -A16-T17-G-18) X.F 9-mer duplex. Two-dimensional NMR experiments establish that the X.F 9-mer helix is right-handed with Watson-Crick A.T and G.C base pairing on either side of the lesion site. NOEs are detected from the methylene protons of the exocyclic ring of X5 to the imino protons of G4.C15 and G6.C13 which flank the lesion site, as well as to the H1' and H1" protons of the cross strand F14 tetrahydrofuran moiety. These NMR results establish that the exocyclic adduct X5 is positioned between flanking G4.C15 and G6.C13 base pairs and directed toward the abasic lesion F14 on the partner strand. These studies establish that the exocyclic ring of the 1,N2-propanodeoxyguanosine adduct fits into the cavity generated by the abasic site.
Base Composition↗
NMR structural studies of the ionizing radiation adduct 7-hydro-8-oxodeoxyguanosine (8-oxo-7H-dG) opposite deoxyadenosine in a DNA duplex. 8-Oxo-7H-dG(syn).dA(anti) alignment at lesion site.
Proton NMR studies are reported on the complementary d(C1-C2-A3-C4-T5-A6-oxo-G7-T8-C9-A10-C11-C12).d(G13-G14-T15- G16-A17-A18-T19- A20-G21-T22-G23-G24) dodecanucleotide duplex (designated 8-oxo-7H-dG.dA 12-mer), which contains a centrally located 7-hydro-8-oxodeoxyguanosine (8-oxo-7H-dG) residue, a group commonly found in DNA that has been exposed to ionizing radiation or oxidizing free radicals. From the NMR spectra it can be deduced that this moiety exists as two tautomers, or gives rise to two DNA conformations, that are in equilibrium and that exchange slowly. The present study focuses on the major component of the equilibrium that originates in the 6,8-dioxo tautomer of 8-oxo-7H-dG. We have assigned the exchangeable NH1, NH7, and NH2-2 base protons located on the Watson-Crick and Hoogsteen edges of 8-oxo-7H-dG7 in the 8-oxo-7H-dG.dA 12-mer duplex, using an analysis of one- and two-dimensional nuclear Overhauser enhancement (NOE) data in H2O solution. The observed NOEs derived from the NH7 proton of 8-oxo-7H-dG7 to the H2 and NH2-6 protons of dA18 establish an 8-oxo-7H-dG7(syn).dA 18(anti) alignment at the lesion site in the 8-oxo-7H-dG.dA 12-mer duplex in solution. This alignment, which places the 8-oxo group in the minor groove, was further characterized by an analysis of the NOESY spectrum of the 8-oxo-7H-dG.dA 12-mer duplex in D2O solution. We were able to detect a set of intra- and interstrand NOEs between protons (exchangeable and nonexchangeable) on adjacent residues in the d(A6-oxo-G7-T8).d(A17-A18-T19) trinucleotide segment centered about the lesion site that establishes stacking of the oxo-dG7(syn).dA(anti) pair between stable Watson-Crick dA6.dT19 and dT8.dA17 base pairs with minimal perturbation of the helix. Thus, both strands of the 8-oxo-7H-dG.dA 12-mer duplex adopt right-handed conformations at and adjacent to the lesion site, the unmodified bases adopt anti glycosidic torsion angles, and the bases are stacked into the helix. The energy-minimized conformation of the central d(A6-oxo-G7-T8).d(A17-A18-T19) segment requires that the 8-oxo-7H-dG7(syn).dA18(anti) alignment be stabilized by two hydrogen bonds from NH7 and O6 of 8-oxo-7H-dG7(syn) to N1 and NH2-6 of dA18(anti), respectively, at the lesion site.(ABSTRACT TRUNCATED AT 400 WORDS)
8-Hydroxy-2'-Deoxyguanosine↗
Environmental and biological incidences over predatory aggression in rodents.
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Aggression↗
Site-specific mutagenesis using a gapped duplex vector: a study of translesion synthesis past 8-oxodeoxyguanosine in E. coli.
We have constructed a gapped plasmid vector in which a single defined lesion is introduced, site-specifically, within a single-strand region. Efficiency of translesional synthesis is determined by the number of colonies recovered following transformation of E. coli. The nucleotide sequence of progeny plasmids in the gapped region of the vector reflects incorporation of bases opposite and near the lesion. The analysis detects non-mutagenic as well as mutagenic events. This system was used to establish the mutagenic potential of 2'-deoxy-7,8-dihydro-8-oxoguanosine (8-oxodG), a lesion produced by the action of active oxygen species on DNA. The presence of 8-oxodG did not affect the number of transformants recovered. Most transformants (greater than 99%) contained G:C pairs at the site of the lesion; however, a limited number of targeted G----T transversions were observed in the presence and absence of SOS induction. Base substitutions neighboring the lesion, reported for an in vitro system, were not observed. We conclude that the 8-oxodG lesion in DNA is weakly mutagenic in E. coli.
8-Hydroxy-2'-Deoxyguanosine↗
Rupture of arteriovenous fistula after in situ saphenous vein bypass.
Residual saphenous vein tributaries function as arteriovenous fistulas after in-situ lower extremity bypass. Whether or not all of these tributaries need to be ligated at the time of bypass is controversial since many will close spontaneously. Other consequences of retained fistulas range from local skin problems to diminished graft flow and ultimate graft thrombosis. A complication not previously reported is rupture of a retained arteriovenous fistula. This unusual and potentially catastrophic complication should be discoverable at an earlier stage by periodic graft surveillance by means of duplex sonography. The routine policy of selective ligation of saphenous vein tributaries needs to be reexamined.
Aged↗
Isolation and characterization of oligodeoxynucleotides containing dG-N2-AAF and oxidation products of dG-C8-AF.
Decadeoxynucleotides containing N-(deoxyguanosine-N2-yl)-2-acetylaminofluorene (dG-N2-AAF) and three recently described products of oxidation of N-(deoxyguanosine-8-yl)-2-aminofluorene (dG-C8-AF) were isolated and characterized. dG-N2-AAF was synthesized; its structure was established by mass spectroscopic and 1H-NMR analysis. Decadeoxynucleotides containing dG-N2-AAF and dG-C8-AAF were prepared by permitting d(CACTAGTCAC) to react with N-acetoxy-AAF and separating the products by HPLC. The decamer containing dG-C8-AAF was incubated under aerobic alkaline conditions. In the presence of 2-mercaptoethanol, the adduct is deacetylated; in the absence of antioxidant, decamers bearing oxidation products are formed. Homogeneity of the modified oligomers was established by polyacrylamide gel electrophoresis. The modified oligodeoxy-nucleotides will be used to introduce dG-N2-aminofluorene adducts and oxidative lesions, site-specifically, into DNA, thereby to correlate these adducts with their mutagenic properties.
2-Acetylaminofluorene↗
A decade of atrial natriuretic factor research.
Present views on the biological significance of atrial natriuretic factor (ANF) relate this polypeptide hormone to the regulation of blood pressure and volume through its modulating effects on renal function, on blood vessel tone and permeability, and on the renin-angiotensin-aldosterone system. Although very important advances in the understanding of ANF have been made over the decade since its discovery, some fundamental facts about ANF biosynthesis and release remain to be elucidated. Stretch-induced enhancement of ANF release appears as the most significant mechanism underlying the endocrine response of the atria to acute volume load. This response decays over a period of minutes, indicating that chronic stimulation of ANF release involves mechanisms different from, or in addition to, those acting during acute stretch-stimulated release. In neither acute nor chronic conditions are the cellular or molecular mechanisms underlying ANF release understood. To better understand long-term stimulation of ANF release, we have conducted extensive in vitro testing of several hormones and neurotransmitters to determine their ability to modify ANF release. From these studies, clear-cut evidence of ANF stimulation was obtained with the vasopressor peptide endothelin. Investigations on the cell and molecular biology of cardiac muscle development and hypertrophy have shown that ANF is involved in cardiac growth. The role played by ANF in these processes is now being determined, but this is one line of evidence that suggests that this hormone, together with other natriuretic peptides, may have autocrine or paracrine functions.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Cervical length may change during ultrasonographic examination.
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Cervix Uteri↗
Measurement of cervical length in pregnancy: comparison between vaginal ultrasonography and digital examination.
Evaluation of the gravid cervix uteri is an important part of prenatal care, especially in the patient at risk for preterm birth. Seeking a method of cervical length measurement that could be used easily regardless of patient habitus, location of the cervix, and gestational age, we used a vaginal probe with a 240 degrees scanning angle in gravidas at various gestational ages to test the theoretical advantages of the wide scanning angle. Among the first 201 examinations, cervical length was measured successfully in 99.5% of cases. This success rate compares favorably with those of abdominal sonography and vaginal sonography using the standard 90 degrees scanning angle sector probes. We also compared this method with digital examination in a double-blind fashion. Only a fair degree of association between sonographic cervical measurements and measurements obtained by digital examination was found, reflected in a correlation coefficient of 0.49.
Cervix Uteri↗
NMR studies of exocyclic 1,N2-propanodeoxyguanosine adducts (X) opposite purines in DNA duplexes: protonated X(syn).A(anti) pairing (acidic pH) and X(syn).G(anti) pairing (neutral pH) at the lesion site.
Proton and phosphorus two-dimensional NMR studies are reported for the complementary d(C1-A2-T3-G4-X5-G6-T7-A8-C9).d(G10-T11-A12-C13-A14-C15-A 16-T17-G18) nonanucleotide duplex (designated X.A 9-mer) that contains a 1,N2-propanodeoxyguanosine exocyclic adduct, X5, opposite deoxyadenosine A14 in the center of the helix. The NMR studies detect a pH-dependent conformational transition; this paper focuses on the structure present at pH 5.8. The two-dimensional NOESY studies of the X.A 9-mer duplex in H2O and D2O solution establish that X5 adopts a syn orientation while A14 adopts an anti orientation about the glycosidic bond at the lesion site. The large downfield shift of the amino protons of A14 demonstrates protonation of the deoxyadenosine base at pH 5.8 such that the protonated X5(syn).A14(anti) pair is stabilized by two hydrogen bonds at low pH. At pH 5.8, the observed NOE between the H8 proton of X5 and the H2 proton of A14 in the X.A 9-mer duplex demonstrates unequivocally the formation of the protonated X5(syn).A14(anti) pair. The 1,N2-propano bridge of X5(syn) is located in the major groove. Selective NOEs from the exocyclic methylene protons of X5 to the major groove H8 proton of flanking G4 but not G6 of the G4-X5-G6 segment provide additional structural constraints on the local conformation at the lesion site. A perturbation in the phosphodiester backbone is detected at the C13-A14 phosphorus located at the lesion site by 31P NMR spectroscopy. The two-dimensional NMR studies have been extended to the related complementary X.G 9-mer duplex that contains a central X5.G14 lesion in a sequence that is otherwise identical with the X.A 9-mer duplex. The NMR experimental parameters are consistent with formation of a pH-independent X5(syn).G14(anti) pair stabilized by two hydrogen bonds with the 1,N2-propano exocyclic adduct of X5(syn) located in the major groove.
Base Composition↗
NMR studies of abasic sites in DNA duplexes: deoxyadenosine stacks into the helix opposite acyclic lesions.
Proton and phosphorus NMR studies are reported for two complementary nonanucleotide duplexes containing acyclic abasic sites. The first duplex, d(C-A-T-G-A-G-T-A-C).d(G-T-A-C-P-C-A-T-G), contains an acyclic propanyl moiety, P, located opposite a deoxyadenosine at the center of the helix (designated APP 9-mer duplex). The second duplex, d(C-A-T-G-A-G-T-A-C).d(G-T-A-C-E-C-A-T-G), contains a similarly located acyclic ethanyl moiety, E (designated APE 9-mer duplex). The ethanyl moiety is one carbon shorter than the natural carbon-phosphodiester backbone of a single nucleotide unit of DNA. The majority of the exchangeable and nonexchangeable base and sugar protons in both the APP 9-mer and APE 9-mer duplexes, including those at the abasic site, have been assigned by recording and analyzing two-dimensional phase-sensitive NOESY data sets in H2O and D2O solution between -5 and 5 degrees C. These spectroscopic observations establish that A5 inserts into the helix opposite the abasic site (P14 and E14) and stacks between the flanking G4.C15 and G6.C13 Watson-Crick base pairs in both the APP 9-mer and APE 9-mer duplexes. The helix is right-handed at and adjacent to the abasic site, and all glycosidic torsion angles are anti in both 9-mer duplexes. Proton NMR parameters for the APP 9-mer and APE 9-mer duplexes are similar to those reported previously for the APF 9-mer duplex (F = furan) in which a cyclic analogue of deoxyribose was embedded in an otherwise identical DNA sequence [Kalnik, M. W., Chang, C. N., Grollman, A. P., & Patel, D. J. (1988) Biochemistry 27, 924-931]. These proton NMR experiments demonstrate that the structures at abasic sites are very similar whether the five-membered ring is open or closed or whether the phosphodiester backbone is shortened by one carbon atom. Phosphorus spectra of the APP 9-mer and APE 9-mer duplexes (5 degrees C) indicate that the backbone conformation is similarly perturbed at three phosphodiester backbone torsion angles. These same torsion angles are also distorted in the APF 9-mer but assume a different conformation than those in the APP 9-mer and APE 9-mer duplexes.
Base Composition↗
Aggression in male mice: rapid-onset attack of lactating female mice following termination of hyperphysiological testosterone treatment.
Gonadally-intact or castrated and testosterone-(T) treated male mice display aggressive behavior towards olfactory-bulbectomized male (OBM) stimuli, but not towards lactating female (LF) stimuli. By comparison, T-treated female mice display aggressive behavior towards both OBM and LF stimuli. The purpose of the present experiment was to determine if male mice given hyperphysiological T-treatment would display "female-typical" attack of OBM and LF stimuli. Hyperphysiological T-stimulation did not lead to the display of aggressive behavior towards OBM and LF stimuli; only OBM stimuli were attacked, suggesting a qualitative behavioral sex difference in response to T. However, the major finding of this study occurred following the termination of T-treatment. Castrated males that had previously received hyperphysiological T-treatment began to attack LF stimuli within 48 hr of treatment termination. By comparison, castrated males that had previously received physiological T-stimulation, as well as a gonadally-intact control group, generally began to attack LF stimuli 3-4 weeks following treatment-termination/castration. It is suggested that this unusual treatment-termination-induced behavioral display occurs via neurochemical mediation.
Aggression↗
Differential effects of dietary fat on the tissue-specific expression of the apolipoprotein A-I gene: relationship to plasma concentration of high density lipoproteins.
Isocaloric substitution of polyunsaturated fat for saturated fat reduces concentrations of total plasma cholesterol and high density lipoproteins (HDL) in nonhuman primates. The biochemical mechanisms through which polyunsaturated fat lowers plasma HDL concentrations are not well understood but must involve changes in HDL production or HDL clearance from plasma, or both. To determine whether dietary polyunsaturated fat (P/S = 2.2) alters apolipoprotein (apo) A-I production, African green monkeys (Cercopithecus aethiops) were fed diets containing polyunsaturated fat or saturated fat (P/S = 0.3) each in combination with high (0.8 mg/kcal) and low (0.03 mg/kcal) amounts of dietary cholesterol. Animals fed polyunsaturated fat at either cholesterol level had lower plasma concentrations of total cholesterol and HDL cholesterol. Plasma apoA-I concentration was reduced by 16% by polyunsaturated fat in the high cholesterol group. The rate of hepatic apoA-I secretion, as estimated by the accumulation of perfusate apoA-I during recirculating liver perfusion, was reduced by 19% in animals consuming the high cholesterol, polyunsaturated fat diet. Hepatic apoA-I mRNA concentrations, as measured by DNA-excess solution hybridization, also were reduced by 22% in the high cholesterol, polyunsaturated fat-fed animals. In contrast, intestinal apoA-I mRNA concentrations were not altered by the type of dietary fat. Plasma apoA-II and hepatic apoA-II mRNA concentrations also were not altered by the type of dietary fat. These data indicate that dietary polyunsaturated fat can selectively alter the expression of the apoA-I gene in a tissue-specific manner.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗