DNA structure in which an adenine-cytosine mismatch pair forms an integral part of the double helix.

Extensive studies using one- and two-dimensional 1H NMR at 500 MHz revealed that the oligonucleotide d(CGCCGCAGC) in solution at 5 degrees C forms a double helix under conditions of high salt (500 mM in NaCl, 1 mM sodium phosphate), low pH (pH 4.5), and high DNA concentration (4 mM in duplex). The presence of very strong nuclear Overhauser effects (NOEs) from base H8/H6 to sugar H2',H2" and the absence of NOE from base H8/H6 to sugar H3' suggested that the oligomer under these solution conditions forms a right-handed B-DNA double helix.

Ten to fourteen residue peptides of Alzheimer's disease protein are sufficient for amyloid fibril formation and its characteristic x-ray diffraction pattern.

The molecular basis of fibril formation in Alzheimers disease was explored by electron micrographic and x-ray diffraction analysis of a series of synthetic peptides corresponding to portions of the amino acid sequence of beta protein and that of its putative precursor. A minimum 14 residue peptide was identified that formed typical amyloid fibrils under physiological conditions. Of these 14 residues, 10 were sufficient to give an identical 4.

A cytosine . cytosine base paired parallel DNA double helix with thymine . thymine bulges.

500 MHz 1H NMR studies using 2D-NOESY indicate that the oligonucleotide d(CTCTCT) at low pH forms a parallel double helix with cytosine . cytosine base pairs and thymine . thymine bulges.

500-MHz 1H NMR study of poly(dG).poly(dC) in solution using one-dimensional nuclear Overhauser effect.

Secondary structures of poly(dG).poly(dC) and poly(dG).poly(dm5C) in solution are determined by nuclear Overhauser effect (NOE) measurements on GH8-deuterated and -nondeuterated DNAs with low presaturation pulse lengths (10-25 ms) and low-power and prolonged accumulations in the range of 50,000-72,000 scans.

NOE data at 500 MHz reveal the proximity of phenyl and tyrosine rings in enkephalin.

Met5-enkephalin-a pentapeptide (Tyr-Gly-Gly-Phe-Met)-can exist in two possible folded arrangements with a rigid two-hydrogen-bonded network. In one arrangement, a Gly 2-Gly 3 beta-bend is formed and in the other a Gly 3-Phe 4 beta-bend. The two conformations are distinguished by the spatial relation of Tyr 1 and Phe 4: in the Gly 2-Gly 3 beta-bend, Tyr 1 and Phe 4 can be brought close to each other while in the Gly 3-Phe 4 beta-bend they are far apart (greater than 5 A).

Effect of phencyclidine on the metabolism of individual brain proteins.

The effect of phencyclidine on the metabolism of a selected number of rat brain proteins was determined using two-dimensional gel electrophoresis and quantitative fluorography. When rats were injected with phencyclidine, modulation of individual protein metabolism occurred in the pituitary and cortex. That is, a few proteins showed increased and others decreased incorporation of [35S]methionine, whereas total protein metabolism was unaltered.

Structure of poly(dA).poly(dT) is not identical to the AT rich regions of the single crystal structure of CGCGAATTBrCGCG. The consequence of this to netropsin binding to poly(dA).poly(dT).

The basic assumption of Dickerson and Kopka (J. Biomole. Str.

Secondary structure of the hybrid poly(rA).poly(dT) in solution. Studies involving NOE at 500 MHz and stereochemical modelling within the constraints of NOE data.

One-dimensional nuclear Overhauser effect (NOE) in nuclear magnetic resonance spectroscopy along with stereochemically sound model building was employed to derive the structure of the hybrid poly(rA).poly(dT) in solution. Extremely strong NOE was observed at AH2' when AH8 was presaturated; strong NOEs were observed at TH2'TH2'' when TH6 was presaturated; in addition the observed NOEs at TH2' and TH2'' were nearly equal when TH6 was presaturated.

Conformational microheterogeneity in a DNA double helix: structure of restriction endonuclease Bam H1 recognition site.

Structural studies using 500 MHz 1H NMR spectroscopy on Bam H1 recognition site d(GGATCC)2 in solution at 19 degrees is reported. The resonances from the sugar ring and base protons have been assigned from the 2D-COSY and NOESY spectra. Analyses of the NOESY cross-peaks between the base protons H8/H6 and sugar protons H2'/H2", H3' reveal that the nucleotide units G2, A3 and C6 adopt (C3'-endo, chi = 200 degrees-220 degrees) conformation while G1, T4 and C5 exhibit (C2'-endo, chi = 240 degrees-260 degrees) conformation.

Untenability of the heteronomous DNA model for poly(dA).poly(dT) in solution. This DNA adopts a right-handed B-DNA duplex in which the two strands are conformationally equivalent. A 500 MHz NMR study using one dimensional NOE.

1D NOE 1H NMR spectroscopy at 500 MHz was employed to examine the structure of poly(dA).poly(dT) in solution. NOE experiments were conducted as a function of presaturation pulse length (50, 30, 20 and 10 msec) and power (19 and 20 db) to distinguish the primary NOEs from spin diffusion.

Netropsin specifically recognizes one of the two conformationally equivalent strands of poly(dA).poly(dT). One dimensional NMR study at 500 MHz involving NOE transfer between netropsin and DNA protons.

Recent observations that the heteronomous structural model for poly(dA).poly(dT) is not found in solution and that in this DNA, the two strands are conformationally equivalent (J. Biomole.

An exponential formula for heart rate dependence of QT interval during exercise and cardiac pacing in humans: reevaluation of Bazett's formula.

A new exponential formula to characterize the human RR-QT relation was evaluated in comparison with Bazett's formula in 16 subjects: 10 healthy, normal men (ages 18 to 30 years) who exercised on a stationary bicycle, and 6 patients (ages 50 to 80 years; 2 women and 4 men) with rate-programmable VVI pacemakers whose rates were changed by an external programmer. The RR and QT intervals for heart rate in the range of 50 to 180 beats/min were measured from electrocardiographic tracings recorded at a paper speed of 100 mm/s. The data from each subject were fitted separately by 4 formulas by an appropriate regression analysis using a statistical package program: (F1) QT = A1 - B1*Exp(-k1*RR); (F2) QT = A2[1-Exp-(-k2*RR)]; (F3) QT = A3* square root (RR) + B3; and (F4) QT = A4* square root (RR), where all A, B, and k are regression parameters.

Solution structure of poly(dA-dT).poly(dA-dT) in low and high salt: a 500 MHz 1H NMR study using one-dimensional NOE.

CD spectra of poly(dA-dT).poly(dA-dT) in low salt (10-100 mM NaCl) and high salt (4-6 M CsF) are different i.e.

Structure and dynamics of netropsin-poly(dA-dT).poly(dA-dT) complex: 500 MHz 1H NMR studies.

Antibiotic netropsin is known to bind specifically to A and T regions in DNA; the mode of binding being non-intercalative. Obviously, H-bonding between the proton donors of netropsin and acceptors N3 of A and O2 of T comes as a strong possibility which might render this specificity. In netropsin there could be 8 proton donors: four terminal amino groups and four internal imino groups.

Fluorescence characterization of the low pH-induced change in diphtheria toxin conformation: effect of salt.

We have examined the effect of pH on diphtheria toxin conformation using intrinsic protein fluorescence and a new fluorescence quenching method. In aqueous solutions, fluorescence indicates toxin conformation undergoes a drastic change at low pH. This conformational change is closely associated with a switch from a hydrophilic conformation to a hydrophobic one, as judged by quenching-detected detergent binding.

Determination of handedness of DNA double helices from NOE difference spectra: the structure of poly(dG-dC).poly(dG-dC) in low salt.

Combined use of shielding constant computations, measurements of chemical shifts and NOE studies reveal that poly(dG-dC).(poly)dG-dC) in low salt solutions exist as a right-handed B-DNA double helix described by Gupta, Dhingra, Sarma, Sarma, Rajagopalan and Sasisekharan, J. Biomole.

Poly(dA-dT).poly(dA-dT) in low salt appears to be a left-handed B-helix combined use of chemical theory, fiber diffraction and NMR spectroscopy.

Poly(dA-dT).poly(dA-dT) can adopt the B- and D- forms in the fibrous state. Theoretical energy calculations and fiber diffraction analyses suggest that there can be three structural models of poly(dA-dT).

Left-handed intercalated DNA double helix: rendezvous of ethidium and actinomycin D in the Z-helical conformation space.

It is now very well recognized that the DNA double helix is conformationally pluralistic and that this flexibility is derived from internal motions due to backbone torsions. But what is less apparent is that such internal motions can occur in a correlated fashion and express themselves in a wide variety of structural motifs and phenomena. For example, flexibility inherent in the DNA molecule can lead to a family of Z-DNA, LZ1 and LZ2 being the two extremes and correlated internal motion can cause LZ1 in equilibrium LZ2 transition.

During B-Z transition there is no large scale breakage of Watson-Crick base pairs. A direct demonstration using 500 MHz 1H NMR spectroscopy.

Monitoring of the Watson-Crick GNH1 proton in poly(dG-dC).poly(dG-dC) at 500 MHz in 90% H2O:10% D2O at 30 degrees C as a function of NaCl concentration (1.5 to 3.

Usefulness of two-dimensional echocardiography in diagnosing right ventricular hypertrophy.

The purpose of this study was to evaluate the usefulness of two-dimensional echocardiographic (2D echo) measurements in diagnosing right ventricular hypertrophy (RVH). These measurements of the right atrium and the ventricle were made in 15 patients with right ventricular hypertrophy and in 11 normal subjects and were as follows: right atrium long axis 2.13 +/- 0.

Reliability of two-dimensional echocardiography in diagnosing fungal endocarditis.

Although the techniques of M-mode and two-dimensional (2D) echocardiography (echo) have been found to be useful in patients with bacterial endocarditis, the 2D findings of fungal endocarditis are not known. In this report, we present the case of a young female narcotic addict with Candida albicans endocarditis in whom we diagnosed a large vegetation by 2D echo. Decision for surgery was made solely on the basis of the 2D-echo findings.

Infective endocarditis due to anaerobic and microaerophilic bacteria.

Seven cases of infective endocarditis (IE) due to anaerobic or microaerophilic bacteria were seen in a period of 42 months at Rancho Los Amigos Hospital (Downey, California), representing 10.6 percent of the total number of 66 cases that carried the diagnosis of IE. Five of the 66 patients had polymicrobial endocarditis.

Preliminary crystallographic investigation of the protein toxin from corynebacterium diphtheriae.

Crystals of diphtheria toxin have been obtained in vapor diffusion experiments from concentrated solutions of potassium tartrate as the precipitating agent. The crystals are trigonal with unit cell dimensions a = b = 97.90 A and c = 100.