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PubMed2006

Patchy distribution fields: sampling distance unit of a spiral survey and reconstruction adequacy.

A mathematical model is used to examine the effects of choosing various units of sampling distance of a spiral acoustic survey on the adequacy of reconstructing patchy distribution fields. The model simulates fish or plankton patches (or gaps) of different shapes and spatial orientations, and an acoustic survey by a spiral of Archimedes along which a unit of sampling distance is set. For comparison, surveys are imitated by parallel transects along which the same unit of sampling distance is set. Adequacy of the reconstructed fields to those originally generated is evaluated by calculating their correlations (r). In the case of a spiral survey, the mathematical experiments conducted show that an immovable field can be reconstructed properly (r(2) > 0.70) if the ratio of the units of sampling distance to the autocorrelation radius for the field averaged in various directions d/R(av) < 1.0-1.5. Regarding immovable fields, the spiral surveys ensure, practically speaking, the same adequacy of the field reconstruction as do surveys by parallel transects with the same unit of sampling distance. In regard to movable fields, a comparison of the results of spiral surveys with those of surveys by parallel transects indicates that the former may ensure even higher adequacy of the field reconstruction than do the latter, provided that the units of sampling distances in these surveys are equal to each other.

Animals↗

PubMed2007

An approach to the validation of novel molecular markers of breast cancer via TMA-based FISH scanning.

Tissue microarrays (TMA) are valuable tools for validating results of array-based comparative genomic hybridization (ACGH) and other translational research applications requiring independent verification of genomic gains and losses by fluorescence in situ hybridization (FISH). However, spatial orientation and accurate manual tracking of the TMA cores is challenging and prone to error. Image analysis combined with core tracking software, implemented via an automated FISH scanning workstation, represents a new approach to FISH and TMA-based validation of novel genomic changes discovered by ACGH in breast and other cancers. Automated large-scale tissue microarray validation FISH studies of genomic gains and losses identified by ACGH for breast cancer are feasible using an automated imaging scanner and tracking/classifying software. Furthermore, by leveraging the bifunctional fluorescent and chromogenic properties of the alkaline phosphatase chromogen fast red K and combining the technology with FISH, correlative and simultaneous phenotype/genotype studies may be enabled.

Biomarkers, Tumor↗

PubMed2004

The advantages of hand-assisted laparoscopy.

The technical challenges of performing laparoscopic renal surgery require fellowship training and are associated with a steep learning curve. For the established urologist in practice, fellowship training is not a reality. As a result of these obstacles, in the late 1990s, laparoscopic renal surgery was entering the domain of the general surgeons who had a large number of laparoscopic procedures at their disposal to develop laparoscopic skills. Hand-assisted laparoscopic renal surgery is a hybrid procedure combining the most salient features of open renal surgery and laparoscopic renal surgery. By allowing the surgeons to place their non-dominant hand into the abdominal cavity, palpation and spatial orientation became possible, lessening the learning curve for laparoscopic surgery. Moreover, hand-assisted laparoscopic surgery could be applied to a variety of renal surgeries, extirpative and reconstructive, with results similar to those already achieved by standard laparoscopy. Throughout the past 5 years, hand-assisted laparoscopy has allowed urologists to incorporate laparoscopic renal surgery into their practices to the benefit of their patients and of their specialty. This review article offers a historical review of the development of hand-assisted laparoscopy and describes the procedures commonly performed today using this technique.

Cystectomy↗

PubMed1980

Left atrial ball thrombus diagnosed by two-dimensional echocardiography.

The diagnosis of the ball thrombus in the left atrium has been very difficult by conventional clinical techniques. In the present case, two-dimensional echocardiography successfully demonstrated a spherical tumor moving in unpredictable directions in the left atrium. M-mode echocardiography did not clearly identify the tumor because of the limited visual width and spatial orientation of the technique; however, simultaneous recordings of the M-mode echocardiogram with phonocardiogram, carotid pulse wave, and electrocardiogram provided some diagnostic clues to the occlusive left atrial tumor. In the absence mitral valve occlusion by the tumor, a logarithmic correlation between the ejection time and the preceding R-R interval, and a negative lines correlation between Q to the first sound interval and the preceding R-R interval were found. In the beat following the appearance of the tumor in the mitral orifice, the sudden shortening of the ejection time and the prolongation of Q to the first sound interval were noted. Both of these findings are indirect evidence of decreased left ventricular filling associated with an elevated left atrial pressure resulting from the sudden mitral orifice obstruction by the tumor. Detailed analysis of the data obtained by the conventional noninvasive techniques could provide critical clues for the diagnosis of the occlusive left atrial tumor.

Blood Coagulation↗

PubMed1985

Relative wall thickness analysis by two-dimensional echocardiography.

M-mode echocardiographic relative wall thickness (RWT) has been used extensively as an index of left ventricular hypertrophy. To determine whether the more extensive tomographic sampling and enhanced spatial orientation provided by two-dimensional echocardiography (2DE) might improve the value of RWT analysis, we compared 2DE and M-mode RWT in 69 subjects (19 normals, 13 with aortic stenosis, 22 with aortic regurgitation, and 15 with congestive cardiomyopathy). M-mode results correlated relatively weakly with 2DE RWT (r = 0.62 at end diastole; r = 0.81 at end systole). End-systolic M-mode values were larger than 2DE results, while end-diastolic M-mode values were generally smaller than 2DE results (both p less than 0.001). Thus, in congestive cardiomyopathy M-mode RWT was larger than 2DE end-diastolic results and therefore failed to distinguish between cardiomyopathy, aortic regurgitation, and normals. We conclude that M-mode and 2DE analysis of RWT yield disparate results. Moreover, 2DE may enhance the value of RWT in the assessment of left ventricular hypertrophy due to volume overload and cardiomyopathy.

Adolescent↗

PubMed1981

Reproducibility of left ventricular internal dimensions with M mode echocardiography: effects of heart size, body position and transducer angulation.

Analysis was made of the variables of heart size, body position and transducer angle affecting the reproducibility of left ventricular internal dimensions as measured with M mode echocardiography. Echocardiograms were recorded in 24 subjects as the thorax was incrementally rotated and tilted. Transducer angle was noted from a three plane level attached to the probe. Constants were the technician, transducer placement and the interpreter. Heart rates varied insignificantly; respirations were held. Groups A and B were defined by their initial left ventricular internal dimensions at end-diastole (LVIDd): 49 +/- 5.9 and 73 +/- 8.6 mm (group mean +/- standard deviation). With body position constant the measurement error between duplicate recordings of LVIDd was +/- 1.2 mm (coefficient of variation = 1.8 percent) in Group A and +/- 4.5 mm (coefficient of variation = 4.6 percent) in Group B (p less than 0.001). Transducer angle varied 12 degrees between duplicate recordings in both groups. As the position of the thorax changed, the transducer followed, maintaining approximately the same incline with the chest wall. In both groups errors for combined LVIDd recorded with rotation and tilt, respectively, were unchanged from the duplication error. Thus, when the spatial orientation between the transducer and heart is held constant, it is the size of the heart that determines the reproducibility of the measurement of left ventricular internal dimensions.

Cardiac Volume↗

PubMed1982

Echocardiographic study of abnormal position and motion of the posterobasal wall of the left ventricle in cases of giant left atrium.

In 35 of 70 patients with rheumatic mitral valve disease, two dimensional echocardiography revealed the posterobasal wall of the left ventricle to be entrapped between the left ventricular and atrial cavities and bent inward. The motion of the bending segment was paradoxical. This abnormality was assumed to be induced by the left atrial dilatation extending inferiorly behind the left ventricle, because the length of the bending segment correlation with the left atrial dimension. There was no correlation between the degree of abnormal bending and left atrial pressure, mitral valve pressure gradient or left ventricular dimension. The systolic excursion of the posterobasal wall of the left ventricle was reduced according to the length of the bending segment. This abnormal feature was also observed in five postmortem heart specimens with an extremely dilated left atrium. The macroscopic and microscopic findings in the myocardium of the bending segment were not different from those of the remaining segment of the left ventricle. Therefore, the asynergic motion of the bending segment is assumed to be caused by the abnormal spatial orientation of the left ventricle and the left atrium. It should be considered that the giant left atrium not only oppresses the surrounding organs but also affects the left ventricle.

Adult↗

PubMed1985

Effect of basic pacing cycle length on sinus node refractoriness in the rabbit.

The effect of basic pacing cycle length on sinus node refractoriness was investigated. In 18 rabbit right atrial preparations, the sinus node effective refractory period (SNERP) was measured at multiple basic pacing cycle lengths. In 14 experiments SNERP was measured at basic pacing cycle lengths of 400, 350 and 300 ms. The mean SNERP (+/- standard deviation) prolonged from 168 +/- 31 ms at 400 ms to 181 +/- 37 ms at 350 ms to 196 +/- 40 ms at 400 ms (p less than 0.001). To rule out the possibility that rapid stimulation might release acetylcholine and thus prolong refractoriness, 4 more experiments were conducted in the presence of atropine (2 X 10(-6) M), and similar results were obtained. The spatial orientation of refractoriness was examined in 7 experiments. At the same premature interval, shorter basic pacing cycle lengths resulted in block of the premature impulse at a greater distance from the sinus node. Therefore, in sinus node tissue refractoriness increases with shortening of basic pacing cycle length, a response similar to that of the atrioventricular node.

Action Potentials↗

PubMed1976

Localization of left ventricular outflow obstruction by cross-sectional echocardiography.

Cross-sectional echocardiographic studies were performed using a high resolution real time mechanical sector scanner in 70 patients with left ventricular outflow obstruction. Seven separate obstructive patterns were recorded in these patients. An area of aortic narrowing just distal to the aortic valve at the superior border of the left atrium was noted with supravalvular aortic stenosis. With congenital valvular aortic stenosis there was an increase in echo production by the thickened aortic leaflets. During systole these prominent leaflet echoes curved inward toward the center of the aortic root reflecting the systolic doming of the valve. With calcific aortic stenosis, the calcification produced an area of dense linear echoes attached in varying degrees to either the anterior or posterior border of the aortic root. At the subvalvular level three obstructive patterns were recorded; with a discrete subvalvular obstructive membrane two linear echoes apparently produced by the inner margins of the obstructing membrane were recorded in the outflow tract. With more extensive fibromuscular narrowing of the subvalvular area, there was inward bowing of the echoes from both the anterior and posterior walls of the outflow tract. In one case this was a dense shelf-like mass of echoes extending downward from the basal portion of the interventricular septum toward the mid-portion of the anterior mitral leaflet with corresponding systolic anterior motion of the mitral leaflet. In patients with idiopathic hypertrophic subaortic stenosis there was systolic anterior motion of the anterior mitral leaflet beginning just distal to the point of coaptation of the mitral leaflets and extending distally toward the papillary muscles. This report suggests that the enlarged field of vision and spatial orientation provided by the cross-sectional echocardiographic technic should improve our ability to record and characterize areas of obstruction to left ventricular outflow.

Aortic Stenosis, Subvalvular↗

PubMed1977

Principles of echocardiography.

Echocardiography is basically a diagnostic procedure whereby images of the heart are produced using ultrasound. It can be considered a natural means of sensing one's environment in that this basic technic is used by several animals as sonar. The manner in which the images are created is in many ways similar to light. With the standard M-mode examination one obtains a one-dimensional view of the heart whereby distance is plotted against time on a strip chart recorder. Cross-sectional or two-dimensional echocardiography plots distance against distance, and one more accurately recreates a spatially oriented heart on either movie film or videotape. All the availability information thus far indicates that echocardiography offers very little, if any, hazard to the patient.

Echocardiography↗

PubMed1975

Photoinduced convalent crosslinkage, in situ, of Escherichia coli 50 S ribosomal proteins to rRNA.

Irradiation of aqueous solutions of Escherichia coli 50 S ribosomal subunits with 253.7 nm light results in the covalent crosslinkage of the rRNA and protein components. Neither peptide bond cleavage nor protein-protein crosslinkage accompanies the crosslinkage reactionmin addition, substantial photoinduced modifications in the primary structure of the ribosomal proteins, other than crosslinkage to rRNA, are not detected. The crosslinkage of the ribosomal proteins to the rRNA proroceeds in two discrete, dose-dependent steps. The first step, requires an input of up to 3 with 10-20 Quanta of 253.7nm radiation, and results in the crosslinkage of less than half of the ribosomal proteins to the rRNA. The second step requires an input of greater than 3 with 10-20 Quanta of 253.7 nm radiation, and results in the crosslinkage of the remaining ribosomal proteins to the rRNA. The possible relationship of the nature of the corsslinkage reaction to the spatial orientations of the rRNA and protein molecules in the intact 50 S ribosomal subunits is discussed.

Bacterial Proteins↗

PubMed1977

Influence of hydrogen bonding on the rotamer distribution of the histidine side chain in peptides: 1H NMR and CD studies.

Both 1H NMR and circular dichroism pH titration studies on histidine, His-Gly, Gly-His and Gly-His-Gly indicate that the side-chain spatial orientation depends strongly on the vicinal charges. The arrangement of the imidazole side-chain (rotamer population) is shown by the histidine beta and beta' and the glycine methylene proton chemical shifts as well as the vicinal 1H-1H coupling constants 3JCalpha-H-beta-H, beta'-H. For His-Gly and Gly-His-Gly a good correlation can be found between the ionization of the glycine COOH group and the increase of rotamer III (g-g) which is also visualized by circular dichroism through an enhancement of the ellipticity at 212 nm. In these two peptides a hydrogen bond between the imidazolium and the carboxylate group is supposed to stabilize rotamer III at pH 4-5.

Circular Dichroism↗

PubMed1982

Responses of primate spinothalamic neurons located in the sacral intermediomedial gray (Stilling's nucleus) to proprioceptive input from the tail.

Extracellular an intracellular recordings were obtained from 24 spinothalamic neurons located in the intermediomedial gray (Stilling's nucleus) in the S2 and S3 spinal segments of anesthetized adult monkeys (Macaca fascicularis). Most units were spontaneously active. They lacked cutaneous receptive fields but could be excited by subcutaneous receptors. Bending the tail to one side of the animal's body axis excited cells located on the contralateral side of the cord an inhibited ipsilateral cells. The firing rate of each cell was a reproducible function of the angle of the portion of the tail distal to the innervated segment. Cells responded with a burst of spikes to electrical stimulation of low threshold ipsilateral primary afferent fibers in the homosegmental dorsal root. The latency of the underlying synaptic potential was 0.5-0.7 ms from the time of arrival of the afferent volley at the cord, indicating monosynaptic input. Low intensity stimulation of the contralateral homosegmental dorsal root inhibited back-ground activity. The latency of the underlying inhibitory synaptic potential was 0.8-1.1 ms, suggesting crossed disynaptic inhibition. We conclude that sacral spinothalamic tract neurons located in the intermediomedial gray participate in signalling the spatial orientation of the animal's tail.

Animals↗

PubMed1984

Spatial and temporal response properties of secondary neurons that receive convergent input in vestibular nuclei of alert cats.

Responses to rotation in many vertical and horizontal planes were studied in electrically identified secondary vestibular neurons of alert cats. This report concerns secondary neurons that gave responses which could not be explained as due to a summation of semicircular canal inputs. These cells responded to sinusoidal rotation of the cat in any vertical plane, and response phase depended on the plane of rotation. The responses were modeled as the result of summation of two inputs that differed in their spatial orientations and dynamics. Response dynamics and a comparison of responses to vertical and horizontal rotations showed that some cells were sensitive to rotation with respect to gravity. Their responses both to gravity and horizontal rotations argue that these secondary neurons received convergent otolith and canal inputs. Some cells also had oculomotor related discharges and/or responded weakly to neck rotation.

Animals↗

PubMed1985

The distribution and origin of serotonin immunoreactivity in the rat cerebellum.

The distribution of serotonin immunoreactivity in the rat cerebellum was studied using the indirect antibody peroxidase-antiperoxidase (PAP) technique of Sternberger. Furthermore, the origin of these chemically defined cerebellar afferents was studied using a procedure which combines the retrograde transport of horseradish peroxidase (HRP) with the PAP technique. Serotoninergic fibers and varicosities distribute throughout the cerebellar cortex. However, within the cortex there are density variations in the distribution of this indoleamine to the granule cell and molecular layers as well as differences in the spatial orientation of labeled elements, especially in the latter lamina. Serotonin-positive fibers are also present in the Purkinje cell layer. Some of the fibers pass from this layer into the overlying molecular layer while others form a plexus around the somata of Purkinje cells. Subsequent to injections of HRP into the vermis and immediately adjacent portions of the cerebellar cortex, several reticular and raphe nuclei (n.) were found to project to the cerebellum including the paramedian reticular nucleus, n. raphe pallidus, n. raphe obscurus, n. raphe magnus, n. reticularis gigantocellularis, n. reticularis paragigantocellularis, n. pontis oralis, n. reticularis tegmenti pontis and n. centralis superioris. Double-labeling experiments, however, reveal that the neurons giving rise to serotoninergic afferents to the cerebellum are located almost exclusively in the n. reticularis gigantocellularis, the n. reticularis paragigantocellularis and the n. pontis oralis. In conclusion, the findings of the present study further support the view that the cerebellar cortex is not uniform in its histological structure. Although serotoninergic elements are distributed throughout the cerebellar cortex, there are lobular variations in the laminar distribution of this indoleamine. These data suggest that serotonin may be exerting its physiological effect on different populations of cortical neurons in different lobules. Thus this putative neurotransmitter may play different roles in the circuitry of the cerebellum in disparate regions of the cortex. Further, the data obtained in the double-label experiments demonstrate a fairly restricted origin for serotoninergic afferents in the medullary and pontine reticular formation. Moreover, the majority are not located in the raphe nuclei.

Animals↗

PubMed1986

Navigational deficits in weaver mutant mice.

Weaver mutant mice have selective degeneration of cerebellar granule cells. In comparison to normal mice, the weaver mutants made more errors and took a longer time to reach a platform in a water-maze. Results are discussed in terms of a role for the cerebellum in spatial orientation.

Animals↗

PubMed1992

Inhibition of NK cell-mediated cytotoxicity by oxysterols.

Some of the oxidation products of cholesterol (oxysterols) have profound effects on plasma membrane structure and function. The present studies were undertaken to determine the effects of oxysterols on NK cell-mediated cytotoxicity. When mouse spleen cells were preincubated with certain oxysterols, NK cell cytotoxicity was inhibited without loss of effector cell viability. The strongest inhibition was observed with oxysterols that are oxidized at the C-5, C-6, or C-7 positions of the sterol nucleus. Among these, 7 beta-hydroxycholesterol caused more inhibition than 7 alpha-hydroxycholesterol suggesting that the spatial orientation of the hydroxyl group in the beta-position results in a greater perturbation in plasma membrane structure than that oriented in the alpha-position. In contrast, oxysterols that are oxidized at the C-20 and C-25 positions that are located on the C-17 acyl chain had little or no inhibitory effect, suggesting that oxidation in the cholesterol nucleus which is situated closer to the phospholipid headgroups at the lipid bilayer-aqueous interface results in a more profound effect on the plasma membrane physical structure. These results suggest that the lytic function of NK cell is sensitive to alterations in the physical state of its plasma membrane induced by oxysterols.

Animals↗

PubMed1990

Alternative representations of time, number, and rate.

Three facts of time perception are described based upon a temporal generalization task for rats (the peak procedure) in which food reinforcement is delivered on half the trials following the first lever-press response after some fixed interval after signal onset. (1) The mean response rate as a function of time is a smooth, slightly asymmetric, function with a maximum near the time of reinforcement; (2) the response rate on individual trials is characterized by an abrupt change from a state of low responding to a state of high responding and finally another state of low responding (break-run-break pattern); and (3) the mean response rate in 12-s and 20-s peak procedures is similar when plotted against time relative to the time of reinforcement (superposition). An information-processing version of scalar timing theory is described and compared to an alternative connectionist version of scalar timing theory that involves multiple oscillators and an autoassociation network. Psychological, mathematical and biological descriptions of the two versions are described and some possible extensions of the connectionist version are proposed to deal with perception of number, rate, and spatial orientation.

Animals↗