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K Leonard

Publications and source records attributed to K Leonard.

At least 73 records · Page 4Linked to original sources
PubMed1987

Three-dimensional structure of NADH: ubiquinone reductase (complex I) from Neurospora mitochondria determined by electron microscopy of membrane crystals.

NADH: ubiquinone reductase (electron transfer complex I) has been isolated from Neurospora crassa mitochondria as a monodisperse protein-phospholipid-Triton X-100 complex (1:0.04:0.15, by weight). The enzyme is in the monomeric state, has a protein molecular weight of 610,000 and consists of about 25 different subunits. Membrane crystals of the enzyme complex have been prepared by adding mixed phospholipid-Triton X-100 micelles and then removing the Triton by dialysis. Diffraction patterns of the negatively stained membrane crystals extend to about 3.9 nm, with a unit cell size of 19 nm X 38 nm and gamma = 90 degrees. The two-sided plane group packing corresponding to pgg is p22(1)2(1). By combining four sets of tilted views, a low-resolution three-dimensional structure of the protein has been calculated. The structure shows that NADH: ubiquinone reductase extends 15 nm across the membrane, projecting 9 nm from one membrane side and 1 nm from the opposite side. Only about one-third of the total protein mass is located in the membrane. The structure of NADH: ubiquinone reductase is compared with that of ubiquinol: cytochrome c reductase determined by electron microscopy of membrane crystals.

Chromatography, High Pressure Liquid↗
PubMed1987

Distribution of neurotensin binding sites in rat brain: a light microscopic radioautographic study using monoiodo [125I]Tyr3-neurotensin.

The topographic distribution of specifically labeled neurotensin binding sites was examined by light microscopic radioautography in rat brain sections incubated with monoiodo [125I]Tyr3-neurotensin. Preliminary experiments indicated that under the present experimental conditions [125I]neurotensin specifically binds to a single apparent population of sites with a dissociation constant of 7.7 +/- 0.3 nM, and that fixation of the labeled sections with glutaraldehyde ensures regionally proportional retention of more than 70% of bound [125I]neurotensin molecules. High concentrations of [125I]neurotensin binding sites were detected in the olfactory bulb and tubercle, parts of the neocortex, the lateral septum, the diagonal band of Broca, the caudate putamen, the amygdala, the dentate gyrus, the anterior dorsal nucleus of the thalamus, the suprachiasmatic nucleus of the hypothalamus, the medial habenula, the zona incerta, the substantia nigra and the ventral tegmental area. In certain areas, such as in the diagonal band of Broca, the substantia innominata, the nucleus basalis and the pars compacta of the substantia nigra, discrete accumulations of silver grains were apparent over neuronal perikarya and their proximal dendrites. In most areas, however, the label appeared more or less uniformly distributed over nerve cell bodies and surrounding neuropil. In several instances, the labeling conformed with the distribution of cell bodies of origin and terminal aborizations of specific projection systems, suggesting that neurotensin receptors might be distributed both proximally and distally on the plasma membrane of certain neurons. Such putative "neurotensinoceptive" projection systems might involve part of the mesostriatal, mesocortical and mesolimbic dopamine systems, as well as the raphe-prosencephalic serotonin system and the habenulo-interpeduncular and basal forebrain-cortical cholinergic systems. Finally, areas of dense [125I]neurotensin labeling often corresponded to zones previously shown to exhibit intense acetylcholinesterase staining, suggesting the existence of a possible link between the expression of neurotensin binding sites and that of acetylcholinesterase in certain neuronal populations.

Animals↗
PubMed1986

Ultrastructure of native lipoprotein from Escherichia coli envelopes.

The free form of the major lipoprotein from Escherichia coli cells envelopes has been purified to homogeneity by gentle extraction procedures and conventional chromatographic separations in a non-ionic detergent. The morphology of paracrystals obtained from homogeneous protein was investigated by low-dose electron microscopy. Electron diffraction of the paracrystals was consistent with alpha-helices arranged perpendicularly to the main cross-band with a periodicity of 20 nm.

Bacterial Outer Membrane Proteins↗
PubMed1986

Radiotherapy for prostate carcinoma.

The charts of 96 patients who received radiotherapy at The M. S. Hershey Medical Center for their prostatic carcinoma were reviewed. The 4-year NED (no evidence of disease) survival rates for patients receiving between 6,500 and 7,000 rad of external beam radiation (EBR) were 92, 78, 56, and 50% for stages A, B, C, and D1, respectively. The 4-year NED survival rate for stage B patients was 90% for those receiving approximately 6,500 rad of EBR, 75% for those receiving approximately 7,000 rad of EBR, and 71% for those receiving interstitial implants. Bowel or urinary complications occurred in 27% (21% grade I, 3% grade II, and 3% grade III) of those receiving approximately 6,500 rad of EBR, 40% (25% grade I, 10% grade II, and 5% grade III) of those receiving 7,000 rad of EBR, and 0% of those receiving interstitial implants. The effects of stage, grade, and treatment type on NED survival and complications are discussed.

Brachytherapy↗
PubMed1986

Three-dimensional structure of the T-layer of Bacillus sphaericus P-1.

The three-dimensional structure of the regular surface layer of Bacillus sphaericus P-1 (T-layer) was determined to a resolution of ca. 2.5 nm by electron microscopy and image analysis. The T-layer has P4 symmetry, a lattice constant of 13 +/- 0.2 nm, and a thickness of ca. 8 nm. The reconstruction revealed three distinct domains: a major, a minor, and an arm domain. In the z-direction, the domains are arranged in two planes creating two different surface reliefs.

Bacillus↗
PubMed1986

Psychosocial functioning in children of alcoholic fathers, depressed fathers and control fathers.

Children of alcoholics are often viewed as having major psychological problems resulting from their interactions within disturbed family structures. Most studies, however, have selected alcoholics from multiproblem families in which it is difficult to disentangle the impact of alcoholism from concomitant psychosocial and psychiatric problems. Further, few studies have used psychometrically sound measures of alcoholism or child functioning. In this investigation, children of alcoholic, depressed and control (social drinkers and not depressed) fathers were assessed by parents on the Child Behavior Checklist and by teachers on the Conner Teacher Rating Scale and the Myklebust Pupil Rating Scale. Although children of alcoholics and of depressives were rated higher on behavior problems by parents than the children of controls, only a minority of these children received scores indicative of severe impairment. The importance of considering the clinical significance of group differences and of examining the joint impact of alcoholism and other psychopathologies is discussed.

Achievement↗
PubMed1985

Three-dimensional structure of unstained, frozen-hydrated extended tails of bacteriophage T4.

Unsupported, unstained frozen-hydrated extended tails of bacteriophage T4 have been studied by cryo-electron microscopy. Their three-dimensional structure has been reconstructed after correlation and averaging of the information from different particles. While the reconstructions of hydrated tails show all the features found by conventional electron microscopy, they are characterized by an open structure. Individual subunits constituting the axial repeat cannot be outlined unambiguously, as the density connectivity is sensitive to the phase-contrast transfer function effects. In order to minimize these effects, we found that the best data set for three-dimensional reconstruction is composed of layer-lines corrected for the phase-contrast transfer function and an uncorrected equator.

Computers↗
PubMed1985

Arthrin: a new actin-like protein in insect flight muscle.

There are one or more proteins of 50,000 to 60,000 Mr in the thin filaments of insect flight muscle. A protein of 55,000 Mr has been isolated from insect fibrillar flight muscle and called arthrin. Despite its higher molecular weight, arthrin is in many ways like actin. The amino acid composition of arthrin was similar to that of actin. There were similarities in the peptides produced by digesting the denatured proteins and mild digestion of polymerized proteins cleaved similar-sized fragments from arthrin and actin. Polymerized arthrin activated the Mg2+ ATPase of myosin to the same extent as actin and the ATPase was regulated by rabbit or Lethocerus troponin and tropomyosin. Arthrin did not itself act as troponin-T. Electron microscopy of negatively stained specimens showed that arthrin and actin filaments were similar in structure and that arthrin could be decorated by rabbit subfragment-1 to form normal-looking arrowheads. Arthrin formed paracrystals at an optimum concentration of MgCl2 (25 mM) that was somewhat lower than the optimum for actin paracrystals. Optical diffraction showed that the structure of the paracrystals was similar to those formed from actin. The mass of arthrin and actin filaments relative to phage fd was measured by scanning transmission electron microscopy; the relative mass of arthrin and actin was 1.33, in agreement with molecular weight estimations. Therefore arthrin has the properties of a heavy form of actin. The proportion of actin, arthrin and troponin-T in Lethocerus myofibrils was six moles of actin to one mole of arthrin and one mole of troponin-T. The function of arthrin is not known.

Actins↗
PubMed1985

Male violence toward females: victim and aggressor variables.

The present study focused on the effects of two variables that have been proposed as determinants of male violence toward female targets in American society. One target variable, verbal attack, and one aggressor variable, masculine performance, were manipulated. Forty male research participants competed in a reaction-time task with a female confederate who had previously criticized them or remained silent when the males' performance on a physical strength task appeared to be average or considerably below the norms for male performance. The significant interaction between the two variables indicated that inhibitions against harming females were reduced when the male performed poorly on a masculine task in the presence of a female who criticized his performance. Results are discussed in terms of their relevance to control and understanding of male-to-female aggression in the natural ecology.

Achievement↗
PubMed1985

Alcohol-related impairments in male alcoholics and the psychiatric symptoms of their spouses: an attempt to replicate.

This paper reports two attempts to replicate a recent finding by Steinglass linking social-behavioral consequences of drinking with the nonalcoholic spouse's psychiatric symptomatology. Only weak support was obtained for the original findings. Discussion focused on several variables which appeared to be importantly related to the strength and generalizability of relationships under investigation.

Adult↗
PubMed1984

Two-dimensional crystalline sheets of Bacillus stearothermophilus 50S ribosomal particles.

Two-dimensional crystalline sheets of the large ribosomal subunit from Bacillus stearothermophilus have been obtained using a slightly modified procedure to that for growing three-dimensional crystals of the same material. The crystalline subunits are packed within monolayers in a relatively small unit cell, the dimensions of which are closely related to those observed for two forms of the three-dimensional crystals. The packing symmetry is p121, and the optical diffraction patterns of micrographs of negatively stained crystals extend to approximately 3.0 nm.

Crystallization↗
PubMed1983

Structural studies of cytochrome reductase. Subunit topography determined by electron microscopy of membrane crystals of a subcomplex.

Ubiquinol: cytochrome c reductase was isolated from Neurospora mitochondria as a protein-detergent complex and dissociated by mild salt treatment. Three parts were obtained and characterized. Firstly, a complex containing the subunits III (cytochrome b), IV (cytochrome c1), VI, VII, VIII and IX; secondly, a complex containing the subunits I and II; and thirdly, the single subunit V (iron-sulphur subunit). Membrane crystals were prepared from the cytochrome bc1 subunit complex and by combining tilted electron microscopic views of the crystals, a low-resolution three-dimensional structure was calculated. This structure was compared to that of the whole cytochrome reductase (previously determined by electron microscopy of membrane crystals). Protein density absent from the structure of the subunit complex was then attributed to the missing subunits according to their size and shape and their association with the phospholipid bilayer.

Crystallization↗
PubMed1983

Structural studies of cytochrome reductase. Improved membrane crystals of the enzyme complex and crystallization of a subcomplex.

Membrane crystals of mitochondrial ubiquinol: cytochrome c reductase of improved size and long-range order and of the cytochrome bc1 subcomplex have been obtained by a dialysis method. The enzyme--Triton X-100 complex was mixed with Triton phospholipid micelles and the Triton slowly removed by dialysis for 48 hours at pH 5.5 at room temperature or above. The effect of varying the pH and temperature on the shape, size and order of the crystals is described.

Crystallization↗
PubMed1983

Drinking problems of alcoholics: correspondence between self and spouse reports.

The present study examined the level of agreement between alcoholics and their wives on a variety of drinking-related behaviors. The self-report of alcoholics on the Michigan Alcoholism Screening Test (MAST) was compared with a parallel version completed by the wives concerning their husbands' behaviors. The couples evidenced a high level of agreement with respect to the Total MAST score as well as to the Helpseeking subscale. The Recognition of Alcohol Problems subscale manifested relatively lower levels of agreement. Alcoholics tended to under-report on this scale relative to their wives and maintain that they were normal drinkers.

Adult↗
PubMed1983

Patterns of alcohol abuse and family stability.

Male alcoholics and their spouses participating in an ongoing family interaction study were assessed as to drinking patterns, psychiatric symptoms, and marital satisfaction. Analyses of these data indicated that high alcohol consumption was associated with high satisfaction and reduced symptomatology in the spouses of steady but not binge drinkers. Findings are discussed in terms of Steinglass' suggestion that alcohol can have "adaptive" consequences for the marriage and family life of alcoholics.

Adolescent↗