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PubMed1986

Changes in isoenzyme patterns of a cloned culture of nonpathogenic Entamoeba histolytica during axenization.

The axenization of an Entamoeba histolytica isolate with a nonpathogenic isoenzyme electrophoretic pattern (zymodeme) was recently achieved for the first time (15). Forty days after the cells were transferred to the medium used for axenic cultivation, the amebae developed virulence properties, and the zymodeme converted to a pathogenic pattern. To exclude the possibility that the original isolate consisted of two zymodeme populations and that conditions of growth selected for a particular population, the experiment was repeated with a cloned culture of a nonpathogenic (zymodeme III) strain, E. histolytica SAW 1734R clAR, isolated by and obtained from P. G. Sargeaunt. Axenization was accomplished, as before, by transferring trophozoites to TYI-S-33 medium containing a mixture of antibiotics to suppress the growth of the associated bacterial flora and a nutritional supplement consisting of gamma-irradiated bacteria. A change in the hexokinase and phosphoglucomutase isoenzyme pattern was observed 21 days after the amebae had been transferred to the axenic medium but before complete axenization of the amebae had occurred. The change in zymodeme was accompanied by an increase in virulence, as evidenced by the ability of fewer amebae to induce hepatic abscesses in hamsters. A reverse conversion to a nonpathogenic zymodeme was also accomplished by reassociating and subculturing the newly converted pathogenic trophozoites of strain SAW 1734R clAR with the bacterial flora that accompanied this ameba in the original xenic culture. The electromobilities of the hexokinase isoenzymes changed back to their original pattern 7 days after the amebae were returned to xenic growth conditions. Our in vitro results demonstrate that culture conditions and bacterial flora can cause changes in the zymodeme and virulence of a cloned ameba isolate and raise the concern that this could happen also in vivo. Thus, the finding of a particular zymodeme in a culture of E. histolytica isolated from a carrier should not be used to predict a clinical condition or serve as a basis for the recommendation of therapy.

Animals↗

PubMed1988

Anatomy and physiology of visual evoked potentials and electroretinograms.

ERGs are electrical potentials originating in the retina and recorded directly from the corneal surface of the eyes. Flash ERGs are elicited by high intensity flashes either on scotopic or photopic conditions. The origin of the A and B waves of ERG are a combination of photoreceptor potentials, K+ mediated current flow and DC potentials within Müller cells, whereas the C waves are altered K+ fluxes induced by light in the pigment epithelia. Oscillatory potentials are probably related to feedback circuits of the inner layer of the retina. Electroretinograms evoked by pattern are mostly originated in ganglion cells. The use of various visual stimuli allow the selective activation of different retinal structures. Flashes selectively activate retina luminance and color detectors, whereas small pattern stimuli preferentially activate contrast and edge detectors. Visual evoked potentials recorded from the scalp probably originate from multiple cortical visual areas. P-100 response of the visual evoked potential to pattern stimulation is a cortically originated wave either produced exclusively by area 17 or 18 or by a multiplicity of cortical neuronal pools. Visual evoked potentials have important application for the diagnosis of optic nerve disease, assessment in conjunction with pattern ERG of the prognosis of recovery of visual function, and the evaluation of visual physiology and physiopathology.

Animals↗

PubMed1993

Mitochondrial RNA abundance in differentiating human colonic epithelial tumor cells estimated through use of a mitochondrial genome map.

We describe a procedure for quantification of mitochondrial (mt) RNA present in total RNA extracts of HT-29 human colonic adenocarcinoma cells grown under conditions for rapid growth (25 mM glucose) or differentiation (25 mM trehalose or 5 mM butyrate). Purified mt DNA was fragmented into specific coding regions using restriction endonuclease sites predicted from HeLa cell mt DNA sequence and probed with either 32P-labelled mt DNA or cDNA made from total RNA of HT-29 or HeLa cells. The amounts of probe that hybridized to various gene-encoded mt DNA fragments or RNA were quantified by laser densitometry. Use of 13 restriction endonucleases revealed that most if not all the mt DNA of HT-29 and K562 leukemic cells was comparable in size to that of HeLa cells. Relative levels of mt RNA from rapidly growing HT-29 and HeLa cells were lower than those measured for differentiated HT-29 cells induced by either trehalose or butyrate. In rapidly growing HT-29 cells and HeLa cells, the highest levels of specific mt RNAs were those encoded by mt DNA sequences immediately flanking the nested promoters and the heavy-strand replication origin (OH). Expression patterns of specific mt RNAs from HT-29 cells treated with butyrate and with trehalose were similar, but not identical. In either case, the mt RNAs that increased the most were those coded by mt DNA sequences located downstream from the light-strand replication origin (OL), suggesting a novel pattern of expression not seen before.

Butyrates↗

PubMed1977

The topology of hair streams and whorls in man, with an observation on their relationship to epidermal ridge patterns.

Hair slope, whorl, cross and field formation is expressible in a topological form. The mathematical description required suggests an origin for the patterns in a growth process occurring in the upper dermis which determines the patterns of the hair slope. The formulae proposed by Euler, Poincaré and Ludwig are adopted as a descriptive method for the analysis of hair patterning resulting from hair slope. A unitary theory for hair streams and fingerprint patterns is suggested by the discovery, on one remarkable human foetus, of sites where epidermal ridges and convergent hair whorls were combined. Placement of the parietal scalp whorl in man is linked to hominid brain and skull development, and its associated hair field is noted to be bipartite, as revealed through patterns of differential hair loss.

Dermatoglyphics↗

PubMed2005

Evolution of the genetic triplet code via two types of doublet codons.

Explaining the apparent non-random codon distribution and the nature and number of amino acids in the 'standard' genetic code remains a challenge, despite the various hypotheses so far proposed. In this paper we propose a simple new hypothesis for code evolution involving a progression from singlet to doublet to triplet codons with a reading mechanism that moves three bases each step. We suggest that triplet codons gradually evolved from two types of ambiguous doublet codons, those in which the first two bases of each three-base window were read ('prefix' codons) and those in which the last two bases of each window were read ('suffix' codons). This hypothesis explains multiple features of the genetic code such as the origin of the pattern of four-fold degenerate and two-fold degenerate triplet codons, the origin of its error minimising properties, and why there are only 20 amino acids.

Amino Acids↗

PubMed2005

Origin of craniopharyngiomas: implication on the growth pattern.

BACKGROUND: The surgical management of craniopharyngiomas has been among the most challenging neurosurgical procedures because of their complex topographical relationship with surrounding structures and high recurrence rate after subtotal resection. Craniopharyngiomas have been classified only by their location to determine an appropriate surgical approach without due regard to other factors that could affect the surgical results, such as the extent of adhesion to surrounding structures or the nature of the tumor. METHODS: We describe the role of the diaphragm sellae on the growth patterns of craniopharyngiomas from surgical experiences and pathological evidences, suggesting the classification of craniopharyngiomas into three categories by the level of origin and the competence of the diaphragm sellae: a tumor of subdiaphragmatic origin with competent diaphragm sellae, subdiaphragmatic with incompetent diaphragm sellae, and supradiaphragmatic. DISCUSSION: Tumors in each category have shown peculiar topographical relationship with the optic chiasm, third ventricle, and also adhesion extents. The nature of the tumor itself, e.g., the composition of cystic and solid parts, may bring additional minor variations to the topographical features of a craniopharyngioma, but will maintain the major characteristics determined by its level of origin and competence of the diaphragm sellae. CONCLUSION: This classification scheme, which considers the origin level, is clinically relevant and useful because optimal surgical approaches could be designed by considering multiple factors affecting surgical procedure and outcome, including the expected extent of adhesion and preferred sites of recurrence, as well as the topographical location of the tumor. In subdiaphragmatic tumors, which correspond to intrasellar and prechiasmatic tumors, a transsphenoidal approach could be reasonably attempted even with considerable suprasellar extensions because they tend to adhere to the intrasellar structures, and the superior surface of the tumor may be easily separated from the brain structures by pulling. Supradiaphragmatic tumors, however, may need a wider surgical approach that can provide direct vision of the tumor because of possible extensive adhesion.

Craniopharyngioma↗

PubMed2004

Emergence of community structure in terrestrial mammal-dominated ecosystems.

We present a paper that combines empirical and theoretical research about the trophic organization of biological communities. Some regularities are observed in the analysis of the relationship between the trophic structure (how the species are distributed among a set of feeding groups) of a number of African large mammal communities and the type of ecosystem. Different types of ecosystems are characterized by specific patterns in the trophic structure of the mammal community. In order to explain the origin of these patterns, we propose a model defining the underlying dynamic of mammal-dominated ecosystems. The main aim of this study is to show that it is possible to obtain a dynamic explanation of those patterns. The model is shown to spontaneously define different types of structures in community organization, related to those observed. We propose a model that could help to explain the correlation between different environmental factors and the abundance or diversity of herbivores, and which establishes a general mechanism that makes it possible to understand how some rules constrain the assembly of the communities. In addition, the proposed model leads us to see how biological communities can operate in an integrated way, which allows for the acceptance of their changes on large time-scales as evolutionary. In summary, we suggest that communities are unitary structures with coherent properties that result from the self-organizing dynamic of the whole system.

Animals↗

PubMedDate not supplied

Fat patterning in athletes in relation to ethnic origin and sport.

Six skinfold measurements of 92 White, Black and Mexican-American high school varsity female athletes were analysed to identify principal components of fatness and relative fat patterning. As in other athletic and non-athletic samples, two principal components were evident: a first component, accounting for 69% of the variation, was positively related to all skinfold sites, and a second principal component, accounting for 11% of the variation, was correlated positively with extremity sites (particularly lower limb sites) and negatively with trunk sites. The first component (fatness) was significantly related to sport (P less than 0.02) but not ethnicity. The second component (extremity/trunk) was significantly related to ethnicity (P less than 0.01) but not sport. These results, although tentative due to the limited sample size, support our earlier findings on Olympic athletes, i.e., fatness is more influenced by sport and by training than is fat patterning.

Adipose Tissue↗

PubMed1985

The normal mucosal surface pattern of the duodenal bulb: radiologic-histologic correlation.

Similar to the stomach and colon, the duodenum also demonstrates a fine mucosal relief pattern on double-contrast radiographic examination. Two patterns may be identified--fine reticular and "small dot." In order to investigate the origin of these patterns, duodenal bulb specimens were obtained at autopsy, and macroscopic and microscopic features were correlated with radiographic patterns. Findings indicate that the surface patterns identified radiographically on cadaveric specimens and in live patient subjects are due to villi and the collections of barium within the intervening sulci. Knowledge of this normal pattern will prevent misdiagnoses, especially when inflammatory disease of the duodenum is being considered.

Duodenum↗

PubMed1984

Activation sequence and potential distribution maps demonstrating multicentric atrial impulse origin in dogs.

We examined the onset of atrial epicardial excitation by recording unipolar potentials from 360 electrodes arranged in templates affixed to the superior vena cava and right atrium in dogs. Both activation sequence and potential distribution maps were obtained for the period of impulse origin beginning before the surface P wave and continuing through the first 15-20 msec of atrial depolarization. The activation maps demonstrated impulse origin from multiple widely separated sites, resulting in two to three individual wavefronts that merged to form a single widely disseminated wavefront spread over a 50 X 20 mm area by 10-15 msec. Atrial potential maps obtained for the same time periods revealed multiple sites of primary negativity corresponding to the points of impulse origin in the activation maps. The potential distributions and evolution of these maps also indicated the presence of multiple wavefronts originating from widely separated locations, and suggested an extensively dispersed source of impulse origin. One of these sites at the superior cavo-appendicular junction corresponded to the rostral portion of the sinus node and the site of classical unifocal origin. Additional sites of impulse origin and primary negativity distant to the sinus node were noted either concurrently in the same map or in other maps associated with different patterns of impulse initiation. Classical physiological and pharmacological interventions were used to alter adrenergic and cholinergic input to the atrium, and resulted in coincident changes of both the patterns of impulse origin and heart rate. In addition, we examined spontaneous changes in the patterns of impulse initiation which accompanied beat-to-beat changes in cycle length (sinus arrhythmia). There was close agreement between activation and potential maps over the entire steady state and dynamic range of impulse origin. The data can be explained by the concept of a widely distributed system of functionally differentiated but coordinated atrial pacemakers.

Action Potentials↗

PubMed2000

Dynamic readjustment of parental methylation patterns of the 5'-flank of the mouse H19 gene during in vitro organogenesis.

Gametic marks are stably propagated in order to manifest parent of origin-specific expression patterns of imprinted genes in the developing conceptus. Although the character of the imprint has not yet been fully elucidated, there is compelling evidence that it involves a methylation mark. This is exemplified by a region upstream of the H19 gene, which is not only methylated in a parent of origin-specific manner, but also regulates the silencing of the maternal Igf2 and paternal H19 alleles, respectively. We show here that the parental-specific methylation patterns within the differentially methylated domain (DMD) are perturbed in the soma during in vitro organogenesis. Under these conditions, the paternal DMD allele becomes partially demethylated, whereas the maternal DMD allele gains methylation. Despite these effects, there were no changes in allelic Igf2 or H19 expression patterns in the embryo. Finally, we show that although TSA derepresses the paternal H19 allele in ectoplacental cone when in vitro developed, there is no discernible effect on the methylation status of the paternally inherited 5'-flank in comparison to control samples. Collectively, this data demonstrates that the parental mark is sensitive to a subset of environmental cues and that a certain degree of plasticity of the gametic mark is tolerated without affecting the manifestation of the imprinted state.

Alleles↗

PubMed2004

Altered N-myc downstream-regulated gene 1 protein expression in African-American compared with caucasian prostate cancer patients.

PURPOSE: The protein encoded by N-myc downstream-regulated gene 1 (NDRG1) is a recently discovered protein whose transcription is induced by androgens and hypoxia. We hypothesized that NDRG1 expression patterns might reveal a biological basis for the disparity of clinical outcome of prostate cancer patients with different ethnic backgrounds. EXPERIMENTAL DESIGN: Patients who underwent radical prostatectomy between 1990 and 2000 at Veterans Administration Medical Center of New York were examined. We studied 223 cases, including 157 African Americans and 66 Caucasians (T2, n = 144; >/=T3, n = 79; Gleason <7, n = 122; >/=7, n = 101). Three patterns of NDRG1 expression were identified in prostate cancer: (a) intense, predominately membranous staining similar to benign prostatic epithelium; (b) intense, nucleocytoplasmic localization; and (c) low or undetectable expression. We then examined the correlations between patients' clinicopathological parameters and different NDRG1 expression patterns. RESULTS: In this study of patients with equal access to care, African-American ethnic origin was an independent predictor of prostate-specific antigen recurrence (P < 0.05). We also observed a significant correlation between different patterns of NDRG1 expression and ethnic origin. Pattern 2 was less frequent in African Americans (21% versus 38%), whereas the reverse was observed for pattern 3 (60% in African Americans versus 44% in Caucasians; P = 0.03). This association remained significant after controlling for both grade and stage simultaneously (P = 0.02). CONCLUSIONS: Our data suggest that different NDRG1 expression patterns reflect differences in the response of prostatic epithelium to hypoxia and androgens in African-American compared with Caucasian patients. Further studies are needed to determine the contribution of NDRG1 to the disparity in clinical outcome observed between the two groups.

Black or African American↗

PubMedDate not supplied

[Left supraclavicular adenopathy with a neuroendocrine pattern of unknown cause: prostatic carcinoma metastasis].

Contribution of a case report of a male patient presenting with single left supraclavicular adenopathy of initially unknown origin and histologic pattern of neuroendocrine nature, finally traced to the prostate. It is believed that in any male over 45 diagnosed with carcinoma of unknown origin in the supradiaphragm lymph nodes, prostate carcinoma metastasis should also be ruled out using PSA immunostaining and by measuring serum PSA, serum alkaline phosphatase and DRE.

Adenocarcinoma↗

PubMed1987

Effects of cyclophosphamide alone and scheduled methotrexate-5-fluorouracil combination chemotherapy on transplantable R-3327 prostatic adenocarcinoma in F1 hybrid male rat.

Male F1 hybrid rats bearing the R-3327 transplantable adenocarcinoma demonstrating similar growth patterns within the original sample of animals were carefully separated into control and treatment groups for each growth pattern. This assured treatment of tumors with similar cell kinetics within each group. In one group, cyclophosphamide (100 mg/kg) was injected intraperitoneally once every four weeks for eight weeks (total of two doses). In the second group, methotrexate (7.5 mg/kg) followed in ninety minutes by 5-fluorouracil (50 mg/kg) were injected intraperitoneally once each week for eight weeks (total of eight doses). These drug dosages did not depress the white cell count of the animals, and they tolerated the medicines well. Excellent suppression of tumor growth was obtained in each group with the cyclophosphamide treatment group being significant at the 0.01 level and the methotrexate-5-fluorouracil treatment group being significant at the 0.05 level.

Adenocarcinoma↗

PubMed1999

Data convergence in a brain model.

Assuming the existence of encoding synapses that record presynaptic axonal 'on-off' pattern as the content of memory, the author has presented a brain model. In this brain model, the synapses of a neuron work like a static random access memory (RAM) that may encode 2 the power of 10,000 'on-off' patterns, the cell body like a central processing unit (CPU) that produces a signal of 1 or 0 in response to different presynaptic axonal 'on-off' patterns, and the axon like a data bus to form synapse with another neuron. Accordingly, the brain is analogous with a computer made of serial static RAMs amid 14 billions of parallel processing CPUs. Such a brain model converges data with each tier of computation, because there are always more input presynaptic 'on-off' patterns than output axonal 'on-off' patterns in a cortical area. The more computations of the data from the primary perceptive cortices, the more likely the data involving the synapses of central cortices, and the more abstract the content of the memory--hence, in the retrieval of memory, parts of the 'on-off' patterns of the original stimulus may lead to the converged, abstract memory. This can be the mechanism of pattern recognition in the brain.

Brain↗

PubMed2005

On optimal current patterns for electrical impedance tomography.

We develop a statistical criterion for optimal patterns in planar circular electrical impedance tomography. These patterns minimize the total variance of the estimation for the resistance or conductance matrix. It is shown that trigonometric patterns (Isaacson, 1986), originally derived from the concept of distinguishability, are a special case of our optimal statistical patterns. New optimal random patterns are introduced. Recovering the electrical properties of the measured body is greatly simplified when optimal patterns are used. The Neumann-to-Dirichlet map and the optimal patterns are derived for a homogeneous medium with an arbitrary distribution of the electrodes on the periphery. As a special case, optimal patterns are developed for a practical EIT system with a finite number of electrodes. For a general nonhomogeneous medium, with no a priori restriction, the optimal patterns for the resistance and conductance matrix are the same. However, for a homogeneous medium, the best current pattern is the worst voltage pattern and vice versa. We study the effect of the number and the width of the electrodes on the estimate of resistivity and conductivity in a homogeneous medium. We confirm experimentally that the optimal patterns produce minimum conductivity variance in a homogeneous medium. Our statistical model is able to discriminate between a homogenous agar phantom and one with a 2 mm air hole with error probability (p-value) 1/1000.

Algorithms↗

PubMed1981

Stochastic properties of gustatory impulse discharges in rat chorda tympani fibers.

1. The present study was intended to elucidate the role of temporal patterns of impulse discharges of the gustatory primary afferents in the coding of taste qualities by the use of simultaneous analyses of the across-neuron patterning (5) and the temporal patterning of impulses. 2. Impulse discharges of 43 rat chorda tympani fibers elicited by gustatory stimulation (0.1 M NaCl, 0.5 M sucrose, 0.01 N HCl, 0.02 M quinine hydrochloride, 0.3 M KCl, and 0.02 M saccharin sodium) were recorded. The temporal patterns of impulse discharges elicited by these stimuli were statistically analyzed both in an initial dynamic phase and a succeeding stationary phase of responses. In the dynamic phase, the time courses of firing frequency were studied; however, these were not clearly associated with the qualities of taste stimuli. In the stationary phase, the stochastic properties of impulse trains were studied regarding the impulse trains as a stochastic point process (30). In this study, interspike interval histograms (ISI histograms), joint interval histograms, serial correlograms, and autocorrelograms were computed. 3. In general, the distribution patterns of ISI histogram were not absolutely specific to the taste qualities. However, the gamma or the exponential distribution occurred most often with 0.1 M NaCl, and the bimodal or the skewed distribution was dominated with 0.5 M sucrose stimulation among the stimuli tested. The rhythmic discharges did not occur exclusively with the sweet taste stimulation, though they occurred more often with the sweet taste stimulation than with other taste stimulations. The joint interval histogram and the serial correlogram were used to examine the stochastic properties of impulse trains with particular reference to the time dependence in the impulse trains. Generally, the time dependence was not concerned with the taste qualities. 4. The chorda tympani fibers were classified into three types according to the magnitude of responses and the temporal patterns of impulse discharges. The neurons predominantly responsive to NaCl and unresponsive to sucrose were classified as type I neurons. The remaining neurons, which moderately responded to both NaCl and sucrose, were further categorized into type II neurons and type III neurons, depending on their temporal patterns of impulse discharge. The type II neurons tended to show the rhythmic or burstlike firing of impulses in response to more than one kind of taste stimuli. 5. The results showed that the taste quality was represented in the characteristic temporal patterning of impulses as well as in the across-neuron patterning of responses. The possible origin of the temporal discharge pattern and its significance in gustatory information processing were discussed on the basis of the neuron types described above.

Afferent Pathways↗

PubMed1999

The dysmorphic cervical spine in Klippel-Feil syndrome: interpretations from developmental biology.

The authors conducted a study to identify radiological patterns of Klippel-Feil syndrome (KFS), and they present a new interpretation of the origin of these patterns based on recent advances in understanding of embryonic development of the spine and its molecular genetic control. The authors studied radiographs and computerized tomography (CT) scans as well as magnetic resonance images or CT myelograms obtained in 30 patients with KFS who were referred for treatment between 1982 and 1996; the patients had complained of various neuroorthopedic complications. Homeotic transformation due to mutations or disturbed expression of Hox genes is a possible mechanism responsible for C-1 assimilation, which was found to have occurred in 19 cases (63%). Notochordal defects and/or signaling problems, which result in reduced or impaired Pax-1 gene expression, may underlie vertebral fusions. This, together with asymmetrical distribution of paraxial mesoderm cells and a possible lack of communication across the embryonic midline, could cause asymmetrical fusion patterns, which were present in 17 cases (57%). The wide and flattened shape of the fused vertebral bodies and their resemblance to the embryonic cartilaginous vertebrae as well as the process of progressive bone fusion with age suggest that the fusions occur before or, at the latest, during chondrification of vertebrae. The authors suggest that the aforementioned mechanisms are likely to be, at least in part, responsible for the observed patterns in KFS that affect the craniovertebral junction and the cervical spine.

Journal Article↗