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Biomedical subjects

D Moore

Publications and source records attributed to D Moore.

At least 55 records · Page 3Linked to original sources
PubMed1989

Evolutionary remodeling in a visual system through extensive changes in the synaptic connectivity of homologous neurons.

The cellular mechanisms by which nervous systems evolve to match evolutionary changes occurring in the rest of the body remain largely unexplored. In a distal visual neuropil of a previously unexamined ancient dipteran family, Stratiomyidae, homologues of all of the periodic neurons known already from more recent Diptera can be recognized, occupying the same locations within the unit structure. This points to extreme developmental stasis for more than 200 million years, conserving both cell identity and position. The arborizations that some neurons make also have remained conservative, but others show marked differences between families in both size and branching patterns. At the electron-microscopical level, extensive differences in synaptic connectivity are found, some sufficient to radically redefine the systems roles of particular neurons. The findings bear out an earlier prediction that changes in the connectivity matrix linking conserved neurons may have been a major factor in implementing evolutionary change in the nervous system.

Animals↗
PubMed1989

Rapid human chromosome aberration analysis using fluorescence in situ hybridization.

We have used in situ hybridization of repeat-sequence DNA probes, specific to the paracentromric locus 1q12 and the telomeric locus 1p36, to fluorescently stain regions that flank human chromosome 1p. This procedure was used for fast detection of structural aberrations involving human chromosome 1p in two separate experiments. In one, human lymphocytes were irradiated with 0, 0.8, 1.6, 2.4 and 3.2 Gy of 137Cs gamma-rays. In the other, human lymphocytes were irradiated with 0, 0.09, 0.18, 2.0, 3.1 and 4.1 Gy of 60Co gamma-rays. The frequencies (per cell) of translocations and dicentrics with one breakpoint in 1p and one elsewhere in the genome were determined for cells irradiated at each dose point. These frequencies both increased with dose, D, in a linear-quadratic manner. The delta, alpha, and beta coefficients resulting from a fit of the equation f(D)=delta + alphaD + betaD2 to the translocation frequency dose-response data were 0.0025, 0.0027 and 0.0037 for 137Cs gamma-rays, and 0.0010, 0.0041, and 0.0057 for 60Co gamma-rays. The delta, alpha, and beta coefficients resulting from a fit to the dicentric frequency dose-response data were 0.0005, 0.0010 and 0.0028 for 137Cs gamma-rays and 0.0001, 0.0002 and 0.0035, for 60Co gamma-rays. Approximately 32,000 metaphase spreads were scored in this study. The average analysis rate was over two metaphase spreads per minute. However, an experienced analyst was able to find and score one metaphase spread every 10s. The importance of this new cytogenetic analysis technique for biological dosimetry and in vivo risk assessment is discussed.

Cesium Radioisotopes↗
PubMed1989

The influence of time of day on the foraging behavior of the honeybee, Apis mellifera.

The honeybee time sense, or Zeitgedächtnis, is highly adaptive, allowing bees to synchronize their foraging behavior with the peak time of daily floral nectar rhythms. Each foraging group within the honeybee colony shows a high degree of fidelity to one species of flower. Across the day, the temporal accuracy of foraging visits to experimental feeding times varies considerably, being nearly exact for morning-trained foraging groups but becoming less so for foraging groups trained later in the day. The evidence gained in this study suggests that the diel change in accuracy exhibited by foraging groups, which persists after the removal of many potential environmental time cues, is an endogenously driven behavior pattern. Furthermore, it appears that individual bees are continuously and accurately aware of the time of day, but are programmed to forage with greater anticipation to late-day food sources. Therefore, two separate processes contributing to the honeybee time sense are implicated. The first varies with time of day and determines the amount of anticipatory activity directed toward the food source. The second process is invariant across the day and is involved with the individual forager's continuous, accurate awareness of time.

Animals↗
PubMed1989

Early exercise testing and discharge of patients with acute chest pain syndromes.

Forty-nine patients deemed to have a low in-hospital risk after 24 hours observation for suspected myocardial infarction, underwent exercise testing 24-48 hours after admission. Thirty-six patients had adequate exercise tolerance and follow-up of this group at one year, showed that no major cardiac event occurred. Of the 13 patients whose performance was inadequate, five were found to have critical lesions at angiography. Early exercise testing is a useful prognostic test, permitting confident early discharge of patients who do not have threatening coronary disease. If this approach was adopted throughout the country, the number of patients, referred for angiographic assessment prior to loss of myocardium could be substantially, and justifiable increased.

Electrocardiography↗
PubMed1989

Children's use of a verbal-nonverbal consistency principle to infer truth and lying.

Children's use of a verbal-nonverbal consistency principle to infer truth and lying was investigated in 2 experiments. In Experiment 1, kindergarten (5-year-olds), second- (7-year-olds), and fourth-grade (9-year-olds) children judged the truthfulness of stimulus persons whose verbal communication and nonverbal communication varied in valence (positive, neutral, and negative). In Experiment 2, children from the same 3 grades were presented part of the verbal communications on audiotape and a similar set of general verbal communications. They were asked to predict what facial expression the speaker would show if he or she was telling the truth or lying. The findings yielded by both experiments indicated that the use of the verbal-nonverbal consistency principle increased with age. Use of that principle was demonstrated by fourth grade children who judged that telling the truth, as opposed to lying, was shown by a consistency between the affective valence of the verbal and the nonverbal communications.

Affect↗
PubMed1988

Incubation periods for paediatric AIDS patients.

A recent seroprevalence study of newborns indicates that one in 62 children born in New York City has antibodies to the human immunodeficiency virus (HIV). The distribution of incubation periods for paediatric patients is needed to estimate future AIDS case loads from these seroprevalence data. Current estimates of incubation periods for paediatric patients are based on limited data. We use parametric and non-parametric methods to analyse incubation periods for 215 paediatric patients with AIDS whose only known route of infection is maternal. We conclude that incubation periods are longer than previously reported; that there is a distinct knee in the incubation period distribution at seven months which suggests two risk populations; and that there is an increase in incidence which is consistent with exponential growth.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Axonal projections within the brain-retrocerebral complex of the cricket, Teleogryllus commodus.

The cerebral origins and axonal trajectories of neurons projecting to the retrocerebral complex of the cricket, Teleogryllus commodus, were examined in silver-intensified nickel preparations. Spatially separate groups of somata in the pars intercerebralis (PI) and in the pars lateralis (PL), commonly accepted as neurosecretory loci, were found to give rise to axons which terminate in the nervus corporis allati 2, the corpus allatum, or the corpus cardiacum. Additional findings demonstrated a distinct group of somata from the PI whose axons run in the esophageal nerve (stomatogastric nervous system), nine somata in the subesophageal ganglion with axons projecting into the nervus corporis allati 2, and also a small cluster of tritocerebral perikarya with axons terminating in the corpus cardiacum. Somata residing in the PI and PL were found to be compartmentally organized based upon the retrocerebral destinations of their axons. Possible functional consequences of these results with respect to the insect neurosecretory system are discussed.

Animals↗
PubMed1988

Interactions between the tonic and cyclic postural motor programs in the crayfish abdomen.

1. In the crayfish (Procambarus clarkii) abdomen, the superficial flexor and extensor muscles and the motoneurons that innervate them are employed during two completely different modes of behavior: (1) tonic postural adjustments and (2) cyclic movements associated with backwards terrestrial walking. We have tested the possibility that these two behavioral subsystems share at least some of the same tonic premotor interneurons. 2. Of the 108 tonic flexion- and extension-producing interneurons monitored during cyclic pattern generation, only 25 were recruited while 36 were inhibited. None of the recruited interneurons made a measurable contribution to the cyclic motor output. Similarly, none of the 20 inhibitory interneurons of the tonic subsystem recorded in this study was found to play a role in shaping the cyclic motor pattern. 3. Simultaneous activation of single tonic postural interneurons with the cyclic motor pattern revealed that the two behavioral subsystems interact in complex ways. Some tonic interneurons produced motor outputs that overrode the cyclic motor outputs while the motor outputs of other tonic interneurons were completely overwhelmed by the cyclic motor program. Still other tonic interneurons generated motor outputs that predominated over cyclic patterned outputs in some ganglia but were masked by the cyclic motor pattern in other ganglia. 4. Although weak interactions between the two subsystems occur at the premotor level, they have little effect on the normal generation of the cyclic pattern. Stronger interactions apparently occur at the level of the motoneurons and these interactions presumably may form the basis of switching from one behavior to the other. We conclude, therefore, that each behavioral subsystem relies upon its own unique set of premotor interneurons. Finally, those interneurons contributing to the cyclic motor pattern have not yet been identified.

Abdomen↗
PubMed1988

Ammonium ions and glutamine inhibit sporulation of Coprinus cinereus basidia assayed in vitro.

Basidia of Coprinus cinereus (Schaeff.:Fr) S. F. Gray are committed to their developmental pathway, continuing through meiosis and sporulation even when excised from their parental fruit body. A technique is described which permits this in vitro differentiation to be used as a rapid, small-scale bioassay for chemicals which interfere with these morphogenetic processes. Of a range of compounds tested, only ammonium and glutamine, and some structural analogues, were able to inhibit basidium differentiation. Growth was not inhibited; instead the differentiation inhibitors caused vegetative hyphal tips to grow out from regions of the basidial apparatus expected to be in active growth during sporulation. Depending on the stage reached at the time of exposure to the inhibitors, vegetative hyphal tips emerged from the four apical sites for sterigmata, from the tips of sterigmata, from partially formed or abnormal spores, and from the basal regions of the basidium from which paraphyses would be expected to arise. The experiments show that ammonium ions and glutamine halt meiocyte differentiation. Reports of similar effects in other organisms, animals and plants as well as fungi, may imply that sporulation events are generally sensitive to ammonium inhibition.

Agaricales↗
PubMed1988

Semisynthetic pyrrolizidine alkaloid N-oxide antitumor agents. Esters of heliotridine.

The C-9 and C-7 monoesters and C-7, C-9 diesters of heliotridine with (S)-(+) and (R)-(-)-2-hydroxy-2-phenylbutyric acid were prepared, converted into their N-oxides, and compared with the corresponding C-9 monoesters of retronecine in the in vivo P388 lymphocytic leukemia screen. Relative in vitro cytotoxicities of some of the free bases and their corresponding N-oxides were also measured against the A204 rhabdomyosarcoma cell line by using the soft agar colony forming assay. Stereochemistry at C-7 of the necine and at C-2' of the necine acid appears to have a significant effect on the antitumor activity in this system. In the heliotridine series, the configuration of the necic acid has a pronounced effect on the site selectivity (C-7 vs C-9) in esterification with carbodiimidazole. An explanation for this site selectivity is offered.

Animals↗
PubMed1988

In vitro susceptibilities of Nocardia species to newer antimicrobial agents.

The in vitro activities of various quinolones, two newer cephalosporins, and imipenem against 23 strains of Nocardia asteroides, 4 strains of Nocardia brasiliensis, and 4 strains of Nocardia caviae were determined by an agar dilution method. PD-117558, a newer carboxyquinolone, and imipenem were the most active agents tested, inhibiting 90% of N. asteroides isolates at an MIC of 2 micrograms/ml. Of the 23 strains of N. asteroides, 15 were susceptible to cefpirome and 10 were susceptible to ciprofloxacin. The N. brasiliensis and N. caviae strains were very susceptible to PD-117558 (MIC, less than or equal to 1 microgram/ml), moderately susceptible to ciprofloxacin, and resistant to most of the other tested drugs.

Anti-Bacterial Agents↗
PubMed1988

An analysis of structural aberrations in human sperm chromosomes.

We have analyzed structural aberrations in 5,000 sperm chromosome complements obtained from 20 men over a 5-yr period by fusion of human sperm with hamster eggs. Detailed data are presented on 366 abnormal cells with 379 analyzable breakpoints. The frequency of cells with structural aberrations ranged from 1.9% to 14.5% among donors; this interindividual variability was statistically significant (p less than 0.0001). In contrast, repeat samples from individual men showed no significant variation over time. The number of sperm chromosome sets processed per hamster egg had no effect on the frequency with which structural aberrations occurred, nor were sperm chromosome abnormalities altered by varying capacitation or culture conditions. The spectrum of structural aberrations observed in human sperm chromosomes and a chi-square analysis of breakpoints based on DNA content are presented. Although human sperm chromosome abnormalities were visualized with a cross-species system, we believe that they represent an inherent, biologically significant phenomenon.

Animals↗
PubMed1987

Characterization of hyaluronate binding proteins isolated from 3T3 and murine sarcoma virus transformed 3T3 cells.

A hyaluronic acid binding fraction was purified from the supernatant media of both 3T3 and murine sarcoma virus (MSV) transformed 3T3 cultures by hyaluronate and immunoaffinity chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis resolved the hyaluronate affinity-purified fraction into three major protein bands of estimated molecular weight (Mr,e) 70K, 66K, and 56K which contained hyaluronate binding activity and which were termed hyaluronate binding proteins (HABP). Hyaluronate affinity chromatography combined with immunoaffinity chromatography, using antibody directed against the larger HABP, allowed a 20-fold purification of HABP. Fractions isolated from 3T3 supernatant medium also contained additional binding molecules in the molecular weight range of 20K. This material was present in vanishingly small amounts and was not detected with a silver stain or with [35S]methionine label. The three protein species isolated by hyaluronate affinity chromatography (Mr,e 70K, 66K, and 56K) were related to one another since they shared antigenic determinants and exhibited similar pI values. In isocratic conditions, HABP occurred as aggregates of up to 580 kilodaltons. Their glycoprotein nature was indicated by their incorporation of 3H-sugars. Enzyme-linked immunoadsorbent assay showed they were antigenically distinct from other hyaluronate binding proteins such as fibronectin, cartilage link protein, and the hyaluronate binding region of chondroitin sulfate proteoglycan. The apparent dissociation constant of HABP for hyaluronate was approximately 10(-8) M, and kinetic analyses showed these binding interactions were complex and of a positive cooperative nature.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗