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At least 325 records · Page 18Linked to original sources
PubMed1994

Confocal image analysis of spatial variations in immunocytochemically identified calmodulin during pollen hydration, germination and pollen tube tip growth in Nicotiana tabacum L.

Using monoclonal anti-calmodulin antibodies in conjunction with confocal scanning laser microscopy we have analysed the spatial variations in the distribution pattern of calmodulin (CaM) during the sequential events of pollen hydration, germination and tube growth in Nicotiana tabacum. These immunocytochemical observations have been complemented by immunochemical studies wherein the anti-calmodulin antibody raised against pea CaM recognises a polypeptide of c. 18 kDa in the pollen extracts. Digitisation of confocally acquired optical sections of immunofluorescence images reveals that in hydrated pollen a high level of CaM is consistently present in the region of the germinal apertures. Subsequently, with the onset of germination a high CaM concentration was found associated with the plasma membrane of the germination bubble and in the cytoplasm in its vicinity, while in the vegetative cytoplasm a weak diffuse and intense punctate signal was registered. CaM immunostain was also detected in association with the plasma membrane of the tube tips in both short and long pollen tubes. Furthermore, the cytosol of the tubes invariably manifested an apically focused CaM gradient. We were, however, unable to detect any vacuolar association of CaM in the older regions of the pollen tubes. Although punctate immunostain was obvious across the pollen tube numerous punctate structures were invariably present in the extreme tip. The possible implications of these findings in development of cell polarity, polarised growth, maintenance of calcium homeostasis and CaM interactions with other mechanochemical motor proteins in effecting propulsion of organelles during pollen hydration, germination and pollen tube growth are discussed.

Blotting, Western↗
PubMed1985

Odor-related bulbar EEG spatial pattern analysis during appetitive conditioning in rabbits.

Mildly thirsty rabbits were classically conditioned by reinforcement with water to give a discriminative licking response to the presentation of odors. The jaw movement component of the licking conditioned response (JM CR) was elicited only by the reinforced odor; an increase in the relative frequency of sniffing (RR CR) occurred to both reinforced (CS+) and nonreinforced (CS-) odors. Oscillatory electroencephalographic bursts of high-frequency (40-80 Hz) potentials were recorded epidurally from the lateral olfactory bulb with 64-electrode arrays (8 X 8, 3.5 X 3.5 mm) chronically implanted. Emphasis was on comparing bursts during odor presentation with bursts preceding odor arrival on each trial. A "detection" burst was characterized as occurring immediately after odor arrival and before the sniff response. "Discrimination" bursts occurred during the RR CR and before the JM CR onset. Significant air-odor burst differences (together with sniffing) occurred through up to six sessions for both CS+ and CS- odors for "discrimination" bursts but not for "detection" bursts.

Animals↗
PubMedDate not supplied

Geographic variation in vascular mortality in Eurasia: spatial autocorrelation analysis of mortality variables and risk factors.

The geographic variation patterns of vascular mortality and their major risk factors from 68 samples in Eurasia are described in this work. The goodness-of-fit tests and analysis of variance indicate significant differences in incidence of mortality from the studied diseases, as well as in risk factors among the various geographic regions in four age groups. Correlation analysis points out the two general tendencies for the majority of studied traits: (a) significant positive association with latitude and (b) significant negative correlation with longitude. In turn, one-dimensional correlograms showed no specific geographic pattern at least up to 3000 km for all studied variables. However, at the large geographic scale a long-distance differentiation pattern was indicated for total serum cholesterol and body mass index; regional patches--for total death rate, mortality rate from cardiovascular and ischaemic heart diseases, systolic and diastolic blood pressure; and a local patches pattern was detected for mortality rate from stroke. Two-dimensional correlograms uncovered three distinct and significant patterns of variation: (a) a north-south trend for total mortality rate, for death rate from cardiovascular and ischaemic heart diseases, for diastolic and systolic blood pressure and for body mass index; (b) a northwest-southeast pattern for mortality rate from cerebrovascular disease; and (c) local patches for total serum cholesterol.

Adult↗
PubMed2000

Isometric pull and push strengths of paraplegics in the workspace: 2. Statistical analysis of spatial factors.

The effect of reach levels, horizontal angles, and vertical angles on isometric pull and push strengths of male and female was determined. Highly significant increases in men's push strength were found between extreme to maximum reaches, and from extreme to normal reaches. However, for women's push strength, a significant increase was found only between extreme to maximum reach. Significant or highly significant increases were found in men's and women's pull strength between the horizontal angle (theta) sagittal through the active shoulder (90 degrees ) and other angles (0, 45, and 135 degrees ). However, for men's push strength, highly significant increases were found between the horizontal angle 45 degrees from the frontal plane, and other angles. For women's push strength, significant or highly significant increases were found between the horizontal angles 0 degrees and angles of 90 and 135 degrees. For men's and women's pull strength, significant or highly significant increases were found between the vertical angle (phi), 90 degrees, and other angles (-20, 0, and 45 degrees ). Similar increases were found for women's push strength between the 45 degrees angle and other angles. In the design of a workstation for paraplegics that requires pull and push forces, consideration must be given to the spatial factors.

Adult↗
PubMed1998

Spatial-temporal analysis of mobility over the adult age range using the Postural-Locomotor-Manual Test.

BACKGROUND: Mobility measurements were performed on healthy adult subjects to investigate changes over the adult age range and to obtain reference values. METHODS: Ninety-five males (19-90 years, mean 58.2) and 122 females (19-90 years, mean 51.8) were measured using the commercially available Postural-Locomotor-Manual Test (PLM-test). Subjects are required to perform a standard maneuver that is recorded using an optoelectronic technique. RESULTS: Older subjects carried out all phases of the maneuver more slowly than younger subjects. At about the age of 50 years, females showed a more rapid slowing down. Males showed a more gradual decrease over the adult age range. CONCLUSION: The PLM-test provides a fairly simple noninvasive method of assessing motor performance. However, it is important to separate male and female data in the determination of reference values.

Adult↗
PubMed1998

Alcohol consumption and injury in Western Australia: a spatial correlation analysis using geographic information systems.

Geographic information systems technology was used to describe, in geographical terms, the nature and strength of the relationship in Western Australia between alcohol consumption and the rates of related injury: night-time assaults (10 p.m. to 6 a.m.); minor night-time road crashes (10 p.m. to 6 a.m.), weighted by traffic density; and hospital E-code (external-cause) morbidity, weighted by alcohol aetiologic fractions. The data were aggregated by five conventional state regions: northern, central, western, southern and Perth metropolitan. There was a general association, of equal significance for males and females, between estimated per capita alcohol consumption and the selected rates of injury in the five regions. However, the nature and strength of association between alcohol consumption and individual injury measures varied. Night-time assaults and hospital E-code morbidity were strongly, associated with consumption. Minor night-time crashes had only a weak association. The variation in the relationship between alcohol consumption and injury suggests that prevention strategies need to take into account the particular drinking patterns and associated harm that occur in different regions of the state, and to develop a range of targeted responses. High rates of consumption and injury in most country areas support the need for greater regional prevention efforts.

Adolescent↗
PubMed2000

Near-infrared study of fluctuations in cerebral hemodynamics during rest and motor stimulation: temporal analysis and spatial mapping.

We have noninvasively studied the motor cortex hemodynamics in human subjects under rest and motor stimulation conditions using a multichannel near-infrared tissue spectrometer. Our instrument measures optical maps of the cerebral cortex at two wavelengths (758 and 830 nm), with an acquisition time of 160 ms per map. We obtained optical maps of oxy- and deoxy-hemoglobin concentration changes in terms of amplitudes of folding average, power spectrum and coherence at the stimulation repetition frequency, and the phase synchronization index. Under periodic motor stimulation conditions, we observed coherence and frequency or phase synchronization of the local hemodynamic changes with stimulation. Our main findings are the following: (1) The amplitude of the hemodynamic response to the motor stimulation is comparable to the amplitude of the fluctuations at rest. (2) The spatial patterns of the oxy- and deoxy-hemoglobin responses to the stimulation are different. (3) The hemodynamic response to stimulation shows a spatial localization and a level of phase synchronization with the motor stimulation that depends on the stimulation period.

Adult↗
PubMed2002

Spatial coherence analysis applied to aberration correction using a two-dimensional array system.

Complex degree of coherence functions are computed using synthetic and measured ultrasound data to demonstrate noteworthy aspects of coherence analysis in the context of aberration correction. Coherence functions calculated from synthetic data illustrate the importance of proper normalization of the constituent cross-correlation integrals when weak elements and receiver directivity are significant factors. The synthetic data also show that a spike can occur at the zero-lag position of the coherence function when the signal-to-noise ratio is reduced by element directivity near the edges of a large aperture. The latter observation is confirmed by experimental data acquired through tissue-mimicking distributed aberration phantoms using a low f-number two-dimensional array system. The coherence of data acquired at neighboring elements is not changed by time-shift compensation of transmit and receive focusing, but time-shift compensation does improve the coherence of echoes measured over larger separations. The resulting increase in coherence widths evaluated at levels between 0.2 and 0.5 is correlated with narrower -10 dB and -20 dB effective widths in focuses visualized using single-transmit images. Iterative focus compensation methods may benefit from aberration estimation algorithms that take advantage of these longer-range correlations in random-scattering waveforms.

Artifacts↗