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PubMed1994

Within-subject coronal caries distribution patterns: an evaluation of randomness with respect to the midline.

The distribution of caries among homologous surfaces can exhibit three possible patterns: random, aggregated, or regular. In a random caries pattern, caries lesions are randomly distributed among homologous surfaces. An aggregated caries pattern is distinguished by the aggregation of lesions on one side of the mouth or the other to a greater extent than would be expected by chance alone. For a regular caries pattern, the left-right distribution of lesions is more homogenous than would be expected by chance alone. A test statistic based on the left-right distribution of caries lesions among discordant homologous pairs was developed to investigate which of these three caries patterns is present in a representative sample of the adult United States population. The data originated from the National Survey of Oral Health in the US (Employed Adults), 1985-1986. Of the 15,132 subjects studied, 12,776 subjects had 2 or more decayed or filled teeth. (At least 2 carious or filled teeth are required for detection of patterns.) Approximately 50% of these subjects (n = 6,439) had two or more discordant homologous tooth pairs. With these tooth pairs, the hypothesis of a random caries pattern was rejected in favor of an aggregated caries pattern (p < 0.0001). Similar findings were obtained with discordant homologous surface pairs. This aggregation of caries on one side of the mouth or the other may be due to genetic, infectious, and/or environmental factors.

Adolescent↗
PubMedDate not supplied

Cognitive functioning as measured by the WISC-R: do children with learning disabilities have distinctive patterns of performance?

Patterns of performance on the Wechsler Intelligence Scale for Children-Revised (WISC-R) have been proposed as useful tools for the identification of children with learning disabilities (LD). However, most of the studies of WISC-R patterns in children with LD have been plagued by the lack of a typically achieving comparison group, by failure to measure individual patterns, and by the lack of a precise definition of LD. In an attempt to address these flaws and to assess the presence of patterns of performance on the WISC-R, we examined data from 121 children with typical achievement (TA), 143 children with reading disabilities (RD), and 100 children with a specific arithmetic disability (AD), ages 6 to 16 years. The results indicated that the RD and AD groups had significantly lower scores than the TA group on all the Verbal IQ subtests. Many of the children with AD and RD showed a significant difference between Verbal and Performance IQ scores, but so did many of the typically achieving children. Although there were some children with LD who showed the predicted patterns, typically, 65% or more of the children with LD did not. Furthermore, a proportion of the TA group-generally not significantly smaller than that of the RD and AD groups-showed discrepancy patterns as well. Our results indicate that the patterns of performance on intelligence tests are not reliable enough for the diagnosis of LD in individual children. Therefore, it might be more profitable to base the detection of an individual's LD on patterns of achievement test scores.

Adolescent↗
PubMedDate not supplied

The effect of monopolar radiofrequency treatment pattern on joint capsular healing. In vitro and in vivo studies using an ovine model.

The purpose of this study was to compare joint capsular healing after two delivery patterns of monopolar radiofrequency energy: 1) uniform treatment of the joint capsule (paintbrush pattern) and 2) multiple single linear passes (grid pattern). First, an in vitro study was performed to compare the percent shrinkage of these two treatment patterns using the femoropatellar joints (stifles) of six sheep. Monopolar radiofrequency energy (settings, 70 degrees C/15W) was applied to the lateral joint capsule; the treated area was approximately 10 x 10 mm. There was no significant difference in shrinkage between the grid (27% +/- 8.7%) and paintbrush (29% +/- 7.9%) patterns. In the in vivo study, stifles of 24 sheep were randomly assigned to the paintbrush or the grid pattern groups and treatment was performed arthroscopically. Sheep were sacrificed immediately after surgery, or at 2, 6, or 12 weeks after surgery. At 6 weeks after surgery, confocal microscopy demonstrated that treated areas had almost completely repaired in the grid group; some nonviable areas were still present in the paintbrush group. Mechanical testing at 6 weeks indicated that joint capsule in the grid group had better mechanical properties than capsule in the paintbrush group. This study revealed that radiofrequency treatment of joint capsule in a grid pattern allowed faster healing than tissue treated in a paintbrush pattern.

Animals↗
PubMed2003

Identification of signature and primers specific to genus Pseudomonas using mismatched patterns of 16S rDNA sequences.

BACKGROUND: Pseudomonas, a soil bacterium, has been observed as a dominant genus that survives in different habitats with wide hostile conditions. We had a basic assumption that the species level variation in 16S rDNA sequences of a bacterial genus is mainly due to substitutions rather than insertion or deletion of bases. Keeping this in view, the aim was to identify a region of 16S rDNA sequence and within that focus on substitution prone stretches indicating species level variation and to derive patterns from these stretches that are specific to the genus. RESULTS: Repeating elements that are highly conserved across different species of Pseudomonas were considered as guiding markers to locate a region within the 16S gene. Four repeating patterns showing more than 80% consistency across fifty different species of Pseudomonas were identified. The sub-sequences between the repeating patterns yielded a continuous region of 495 bases. The sub-sequences after alignment and using Shanon's entropy measure yielded a consensus pattern. A stretch of 24 base positions in this region, showing maximum variations across the sampled sequences was focused for possible genus specific patterns. Nine patterns in this stretch showed nearly 70% specificity to the target genus. These patterns were further used to obtain a signature that is highly specific to Pseudomonas. The signature region was used to design PCR primers, which yielded a PCR product of 150 bp whose specificity was validated through a sample experiment. CONCLUSIONS: The developed approach was successfully applied to genus Pseudomonas. It could be tried in other bacterial genera to obtain respective signature patterns and thereby PCR primers, for their rapid tracking in the environmental samples.

Base Pair Mismatch↗
PubMed2006

Support for a rare pattern of temperature-dependent sex determination in archaic reptiles: evidence from two species of tuatara (Sphenodon).

BACKGROUND: The sex of many reptiles is determined by the temperature an embryo experiences during its development. Three patterns of temperature-dependent sex determination (TSD) have been defined, but one pattern where only males are produced above an upper temperature threshold (Type IB) is controversial. Here we report new data on the relationship between constant temperature incubation and sexual phenotype in two species of tuatara (Sphenodon), archaic reptiles of enormous zoological significance as the sole representatives of a once widespread reptilian order. RESULTS: In both species, the pattern observed with constant incubation temperatures from 18 to 23 degrees C (or 24 degrees C) supported a female-->male (FM or Type IB) pattern of TSD: in Sphenodon guntheri males were produced above a pivotal temperature of 21.6 degrees C, and in S. punctatus (unnamed subspecies on Stephens Island, Cook Strait), males were produced above a pivotal temperature of 22.0 degrees C. The pivotal temperatures and scaling parameters differed between species (p < 0.001). The thermosensitive period (TSP), where temperature influences gonad morphogenesis, occurs between 0.25 and 0.55 of embryonic development. While it is possible that the more common female-->male-->female (FMF or Type II) pattern exists, with a second pivotal temperature above 23-24 degrees C, we review several lines of evidence to the contrary. Most notably, we show that in S. punctatus, the warmest natural nests during the TSP produce predominantly males. CONCLUSION: An FM pattern of TSD could be currently adaptive in promoting sexual size dimorphism in tuatara. However, an FM pattern has particularly serious consequences for S. guntheri because current patterns of global warming could exacerbate the male bias already present in the relic population.

Journal Article↗
PubMed2005

Percentage density, Wolfe's and Tabár's mammographic patterns: agreement and association with risk factors for breast cancer.

INTRODUCTION: The purpose of this report was to classify mammograms according to four methods and to examine their agreement and their relationship to selected risk factors for breast cancer. METHOD: Mammograms and epidemiological data were collected from 987 women, aged 55 to 71 years, attending the Norwegian Breast Cancer Screening Program. Two readers each classified the mammograms according to a quantitative method (Cumulus or Madena software) and one reader according to two qualitative methods (Wolfe and Tabár patterns). Mammograms classified in the reader-specific upper quartile of percentage density, Wolfe's P2 and DY patterns, or Tabár's IV and V patterns, were categorized as high-risk density patterns and the remaining mammograms as low-risk density patterns. We calculated intra-reader and inter-reader agreement and estimated prevalence odds ratios of having high-risk mammographic density patterns according to selected risk factors for breast cancer. RESULTS: The Pearson correlation coefficient was 0.86 for the two quantitative density measurements. There was moderate agreement between the Wolfe and Tabár classifications (Kappa = 0.51; 95% confidence interval 0.46 to 0.56). Age at screening, number of children and body mass index (BMI) showed a statistically significant inverse relationship with high-risk density patterns for all four methods (all P < 0.05). After adjustment for percentage density, the Wolfe classification was not associated with any of the risk factors for breast cancer, whereas the association with number of children and BMI remained statistically significant for the Tabár classification. Adjustment for Wolfe or Tabár patterns did not alter the associations between these risk factors and percentage mammographic density. CONCLUSION: The four assessments methods seem to capture the same overall associations with risk factors for breast cancer. Our results indicate that the quantitative methods convey additional information over the qualitative methods.

Aged↗
PubMed1981

Pattern of thyrotropin and thyroxine plasma concentrations during the 24-hour sleep-wake cycle in the male rhesus monkey.

The 24-h pattern of the plasma TSH concentration was investigated in five male rhesus monkeys prepared chronically with right atrial catheters and electroencephalogram (EEG) electrodes. The preparation allowed frequent blood sampling (every 15 min), TV monitoring, and EEG recording from the adjacent room for extended periods of time from undisturbed animals. In addition, nap deprivation, 5 h total sleep deprivation, and specific sleep stage deprivation experiments were performed in order to test their influence on the TSH pattern. T4 was also determined in approximately half of the profiles during undisturbed conditions. Both TSH and T4 patterns consisted of low amplitude, high frequency fluctuations which, however, did not exceed the assay variation. TSH showed superimposed higher amplitude spikes at unpredictable times (0-5/24-h). Intra- and interanimal variabilities of both TSH and T4 patterns were high. Power spectral maxima of the TSH time series indicated periodicities between 30-75 min which were not significant. No nyctohemeral difference in the TSH or T4 pattern or their mean concentrations was found, and there was no consistent pattern of a circadian cycle. Independent changes of average TSH and T4 concentrations were seen in 5 of the 16 profiles during undisturbed conditions, under which both hormones were determined. Cross-correlation analysis of the hormonal time series revealed no significant relation between TSH and T4 patterns. The deprivation procedures had no significant influence on the day or nighttime pattern of TSH. Cross-correlation analysis showed no relation between TSH and either activity during the day or sleep stages during the night. It is concluded that in the rhesus monkey, in contrast to man, TSH secretion shows no circadian variation and is not influenced by the sleep-wake cycle.

Animals↗
PubMed1996

Cortisol secretory patterns in Cushing's disease and response to cyproheptadine treatment.

To investigate whether cortisol secretory patterns are associated with a response to cyproheptadine treatment in Cushing's disease, we studied two patients with a hyperpulsatile pattern and one patient with a hypopulsatile pattern before and during chronic cyproheptadine therapy (24 mg daily). In the two patients with a hyperpulsatile cortisol secretory pattern, pituitary magnetic resonance imaging with gadolinium did not reveal a pituitary adenoma, whereas in the patient with a hypopulsatile cortisol secretory pattern, a microadenoma was identified. Plasma cortisol levels were measured every 30 min for 24 h. In the two patients with a hyperpulsatile cortisol secretory pattern, chronic treatment with cyproheptadine resulted in sustained clinical and biochemical improvement and normalization of the median of absolute and relative increments in cortisol spikes. In the patient with a hypopulsatile cortisol secretory pattern, only a reduction of cortisol spikes was noticed during treatment. These results suggest that patients with Cushing's disease who are characterized by a hyperpulsatile cortisol secretory pattern and in whom no pituitary lesion can be identified by magnetic resonance imaging, cyproheptadine treatment may be useful.

Adenoma↗
PubMed1992

Expression patterns of the homeobox gene, Hox-8, in the mouse embryo suggest a role in specifying tooth initiation and shape.

We have studied the expression patterns of the newly isolated homeobox gene, Hox-8 by in situ hybridisation to sections of the developing heads of mouse embryos between E9 and E17.5, and compared them to Hox-7 expression patterns in adjacent sections. This paper concentrates on the interesting expression patterns of Hox-8 during initiation and development of the molar and incisor teeth. Hox-8 expression domains are present in the neural crest-derived mesenchyme beneath sites of future tooth formation, in a proximo-distal gradient. Tooth development is initiated in the oral epithelium which subsequently thickens in discrete sites and invaginates to form the dental lamina. Hox-8 expression in mouse oral epithelium is first evident at the sites of the dental placodes, suggesting a role in the specification of tooth position. Subsequently, in molar teeth, this patch of Hox-8 expressing epithelium becomes incorporated within the buccal aspect of the invaginating dental lamina to form part of the external enamel epithelium of the cap stage tooth germ. This locus of Hox-8 expression becomes continuous with new sites of Hox-8 expression in the enamel navel, septum, knot and internal enamel epithelium. The transitory enamel knot, septum and navel were postulated, long ago, to be involved in specifying tooth shape, causing the inflection of the first buccal cusp, but this theory has been largely ignored. Interestingly, in the conical incisor teeth, the enamel navel, septum and knot are absent, and Hox-8 has a symmetrical expression pattern. Our demonstration of the precise expression patterns of Hox-8 in the early dental placodes and their subsequent association with the enamel knot, septum and navel provide the first molecular clues to the basis of patterning in the dentition and the association of tooth position with tooth shape: an association all the more intriguing in view of the evolutionary robustness of the patterning mechanism, and the known role of homeobox genes in Drosophila pattern formation. At the bell stage of tooth development, Hox-8 expression switches tissue layers, being absent from the differentiating epithelial ameloblasts and turned on in the differentiating mesenchymal odontoblasts. Hox-7 is expressed in the mesenchyme of the dental papilla and follicle at all stages. This reciprocity of expression suggests an interactive role between Hox-7, Hox-8 and other genes in regulating epithelial mesenchymal interactions during dental differentiation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Segment polarity gene interactions modulate epidermal patterning in Drosophila embryos.

Each segment of a Drosophila larva shows a precisely organized pattern of cuticular structures, indicating diverse cellular identities in the underlying epidermis. Mutations in the segment polarity genes alter the cuticle pattern secreted by the epidermal cells; these mutant patterns provide clues about the role that each gene product plays in the development of wild-type epidermal pattern. We have analyzed embryos that are multiply mutant for five key patterning genes: wingless, patched, engrailed, naked and hedgehog. Our results indicate that wild-type activity of these five segment polarity genes can account for most of the ventral pattern elements and that their gene products interact extensively to specify the diverse cellular identities within the epidermis. Two pattern elements can be correlated with individual gene action: wingless is required for formation of naked cuticle and engrailed is required for formation of the first row of denticles in each abdominal denticle belt. The remaining cell types can be produced by different combinations of the five gene activities. wingless activity generates the diversity of cell types within the segment, but each specific cell identity depends on the activity of patched, engrailed, naked and hedgehog. These molecules modulate the distribution and interpretation of wingless signalling activity in the ventral epidermal cells and, in addition, each can contribute to pattern through a pathway independent of the wingless signalling pathway.

Animals↗
PubMed1996

Distinct stages of melanocyte differentiation revealed by anlaysis of nonuniform pigmentation patterns.

The injection of an antagonistic anti-murine c-kit monoclonal antibody ACK2 during mouse embryonic development produced three distinctive pigmentation patterns on the coat of the offspring. Pattern 1 consisted of pigmentation in craniofacial and caudal regions and was induced by an ACK2 injection between 9.5 and 11.5 days post coitum (dpc). In pattern 2, the entire coat was unpigmented and was induced by the injection at around 13.0 dpc. Pattern 3 consisted of pigmented patches spreading ventrolaterally from the dorsoanterior trunk regions towards the anterior and posterior directions and it was induced by ACK2 administered at 14.5-15.0 dpc. We investigated the embryological basis of these nonuniform pigmentation patterns to elucidate the process of melanoblast differentiation between lineage commitment and colonization into developing hair follicles. The results showed the following. (1) Melanocyte differentiation at the embryonic stage from 10.5 to 12.5 dpc progresses in a spatially nonuniform fashion, being faster in the craniofacial and caudal regions than in the trunk; pattern 1 reflects this. (2) Melanoblasts are activated to proliferate synchronously upon entering into the epidermis; pattern 2 correlates with this process. (3) c-kit functions as a survival signal for proliferating melanoblasts in the epidermis. (4) The melanoblasts that enter developing hair follicles can survive without a c-kit signal; pattern 3 essentially represents the hair follicles colonized by these cells. Analysis of the melanoblast distribution of ls/ls embryos that bear a loss-of-function mutation in the endothelin 3 gene suggested that endothelin 3 is required for early melanoblast differentiation before entering into the epidermis, whereas proliferation in the epidermis takes place without this molecule. Based on these data, we propose 4 distinct steps of embryonic melanocyte differentiation: (1) migration in the dermis, which requires both c-kit and endothelin 3; (2) a state before epidermal entry that is resistant to anti-c-kit mAb; (3) cell proliferation after entering the epidermal layer, which requires c-kit and endothelin receptor B but not endothelin 3 and (4) integration into developing hair follicles, which renders melanoblasts resistant to anti-c-kit mAb. Thus, melanoblast differentiation proceeds by alternately repeating c-kit -dependent and c-kit-independent stages and c-kit functions as a survival factor for the proliferating melanoblasts.

Animals↗
PubMed2006

Alterations in the immunohistochemical localization patterns of alpha-smooth muscle actin (SMA) and vimentin in the postnatally developing bovine cryptorchid testis.

Previously, we reported the normal postnatal developmental changes in immunohistochemical localization of alpha-smooth muscle actin (SMA) and vimentin in the bovine testis. In this study, we demonstrate the alterations of these cytoskeletal proteins in the bovine cryptorchid testis as compared to the contralateral scrotal testis during postnatal development. Seminiferous peritubular alpha-SMA did not appear in the cryptorchid testis until 8 months of age, except for very weak intermittent filaments in relatively larger seminiferous tubules. However, a similar peritubular pattern was observed in the 18-month-old cryptorchid and scrotal testes. Moreover, weak expression of alpha-SMA in the straight tubules and rete testes at 5 months of age did not improve until 18 months of age in the cryptorchid testes. The Sertoli cell vimentin in the cryptorchid testes revealed a highly immature pattern at 5 months of age, a pattern similar to a transforming pattern with infranuclear vimentin extensions at 8 months of age, and a pattern that was almost a transforming pattern, but with considerable weakening of the vimentin filaments, at 18 months of age. In conclusion, cryptorchidism may cause considerable delay in testicular myoid cell differentiation and in attainment of the transforming pattern of the Sertoli cell vimentin, which weakens and fails to attain the mature pattern in the cryptorchid testis. These alterations may be related to the structural immaturity and functional failure of postnatally developing bovine testes exposed continuously to body heat.

Actins↗
PubMedDate not supplied

Effects of stimulation pattern on electrical stimulation-induced leg cycling performance.

Electrical stimulation-induced leg cycling (ES-LC) is beneficial for individuals with spinal cord injury (SCI), but cycling performance is often limited because of rapid fatigue of the stimulated muscles. This study evaluated whether a stimulation pattern with a catchlike-inducing pulse train increased force production and hence cycling performance. Five men with SCI performed ES-LC using different stimulation patterns: (1) the standard pattern with ramp modulation, (2) a pattern with no ramp modulation, (3) a pattern with no ramp modulation but with an initial doublet, and (4) a pattern with a middle doublet. None of the experimental patterns resulted in significantly improved cycling performance compared with the standard pattern. However, during the first 3 min of cycling, the current amplitude was significantly higher with the standard stimulation, suggesting that stimulation with no ramp modulation produces more force at the same submaximal current amplitude. The results do not indicate that stimulation with catchlike-inducing trains with the current parameter settings improves ES-LC performance.

Adolescent↗
PubMed2004

Color-pattern modifications and speciation in butterflies of the genus Vanessa and its related genera Cynthia and Bassaris.

We have previously shown that the systemic injection of sodium tungstate, a protein-tyrosine phosphatase (PTPase) inhibitor, to pupae immediately after pupation efficiently produces characteristic color-pattern modifications on the wings of many species of butterflies including Vanessa indica and Cynthia cardui. In these species, the black spots reduced in size in response to the treatment. Similar modifications are occasionally seen in the field-caught aberrant individuals. Exceptionally, however, a C. cardui individual with enlarged black spots ("reversed" modification pattern) has been reported. Here we show that these modified patterns of V. indica and C. cardui are quite similar to the normal color-patterns of other Vanessa species. V. indica with tungstate-induced modifications resembled V. tameamea, V. samani, and Bassaris itea, whereas V. dilecta, V. atalanta, and V. dejeanii are similar to the "reversed" individual. Most features seen in the experimentally-modified V. indica were observed throughout the fore- and hindwings of V. samani. In contrast, the experimentally-induced color-patterns of C. cardui did not parallel variation of Cynthia butterflies. Since it has been proposed that a hypothetical transduction pathway with a PTPase for the scale-cell differentiation globally coordinates the wing-wide color-patterns, our findings suggest that spontaneous mutations in genes in this hypothetical pathway might have played a major role in creating new color-patterns and species in the Vanessa genus but not in the Cynthia genus. This evolutionary mechanism may probably be shared more widely in Lepidoptera, although this would not be a sole determinant for the color-pattern development and evolution.

Animals↗
PubMedDate not supplied

Effect of sperm viability, plasmalemma integrity, and capacitation on patterns of expression of mannose-binding sites on human sperm.

The objective of this study was to characterize patterns of surface expression of mannose-binding sites (MBS) on human spermatozoa while evaluating the influence of sperm viability, plasma membrane integrity, and capacitation, D-Mannose binding sites were visualized by fluorescence microscopy using fluoresceinated mannose-enriched bovine serum albumin (FITC-DMA). To verify the probe specificity, 200 mM D-mannose and D-mannosylated albumin 200 micrograms/mL (DMA) were used as competitive inhibitors. Fluoresceinated bovine serum albumin (FITC-BSA) was used as control. Sperm membrane integrity was checked with a hypoosmotic swelling test (HOST) and sperm viability with Hoechst 33,258 at 1 microgram/mL. Viable spermatozoa with intact plasma membrane presented two main patterns: light bar (weak labeling of the equatorial segment) and slot (labeling of the pre- and postequatorial areas with a negative band in between). These patterns were significantly inhibited when unlabeled D-mannose or DMA were included in the medium. The percentages of spermatozoa displaying these two patterns increases significantly during capacitation. Nonviable spermatozoa with altered plasma membrane integrity presented multiple fluorescent patterns, all of which were present when FITC-BSA was used as the marker. None of them could be suppressed by unlabeled D-mannose or DMA. Viable spermatozoa displayed two main patterns which increased their incidence with capacitation and may be the only specific patterns for surface MBS. Other patterns detected in spermatozoa bearing altered plasma membranes may be due to nonspecific BSA binding or intracellular MBS recognition.

Animals↗
PubMedDate not supplied

Hyalinizing trabecular carcinoma of the thyroid gland: report of two cases of follicular cell thyroid carcinoma with hyalinizing trabecular pattern.

Recently tumors have been reported that have an architectural pattern and cellularity similar to hyalinizing trabecular adenoma and show either parafollicular differentiation or histological findings suggestive of malignant neoplasm of the follicular cells. This study describes two cases of thyroid carcinoma of follicular cells that displayed a hylinizing trabecular pattern. The first case was a 25-year-old euthyroid woman with a cold thyroid nodule in the right lobe. On fine needle aspiration a diagnosis of papillary carcinoma was rendered. The thyroidectomy disclosed a 2-cm, firm, brown, encapsulated tumor in the right lobe. The tumor had a growth pattern and cytologic features similar to those described in hyalinizing trabecular adenoma. The differences between these neoplasms were the presence of mitotic figures, prominence of the nucleolus, capsular blood vessel invasion, and microtubule groups in the endoplasmic reticulum. The second case was a 19-year-old euthyroid woman with a cold thyroid nodule in the left lobe. A cytologic diagnosis of follicular proliferation was rendered. A 4-cm, firm, whitish, encapsulated nodule was found in the left lobectomy. The tumor cells were arranged in two clear-cut patterns: a trabecular hyalinizing pattern with a small focus of papillary growth, and a follicular pattern. These findings confirm the existence of malignant thyroid tumors with a hyalinizing trabecular pattern and illustrate the nonspecificity of this peculiar pattern, since it may also be seen in papillary carcinomas of the thyroid. The relationship between hyalinizing trabecular adenoma and papillary carcinoma of the thyroid is commented on.

Adenocarcinoma, Follicular↗
PubMed1999

From ultradian to infradian rhythms: LH release patterns in vitro.

In the present study, we examined in vitro luteinizing hormone (LH) release patterns from pituitaries and from pituitary cell cultures (3 and 7 days in culture) to elucidate the endogenous period generated by the gonadotroph cell population and to evaluate the relationship between the basic period generated at the cellular level and the output pattern observed at the organ level. In addition, we examined the effect of photic environmental signals perceived by the animals on LH release patterns from pituitaries in vitro. When the animals were exposed to circadian photoperiodic signals, the in vitro LH release pattern from the pituitaries exhibited ultradian, circadian, and infradian frequencies. When the animals were exposed to continuous illumination, the in vitro patterns exhibited only ultradian and infradian frequencies. Furthermore, free running is a process, not a state. This process is driven by a change in the relative dominance of different frequencies that construct the pattern without changing the basic period length. Evaluation of the relative dominance of the different frequencies that construct the pattern indicates that, although infradian oscillators may take part in shaping the output pattern, the basic rhythm generated by the pituitary cells is in the ultradian domain. The results obtained from the examined system suggest that an endogenous oscillator is a cellular entity with ultradian periodicity, and that the rhythmic output of many biological variables is structured by various ultradian components that construct the circadian and infradian output rhythms.

Activity Cycles↗
PubMed2003

Relationship between topographic patterns and corneal astigmatism in Korean adults.

The anterior corneal surface is one of the most important elements determining the optical performance of the eye. Corneal topography provides quantitative data about the anterior corneal surface. We studied the corneal topography of 200 normal corneas in 110 adult subjects. All of the eyes were examined using the Corneal Analysis System (EyeSys 2000, Houston, Texas). The topographic maps were grouped into the following patterns: round, oval, symmetric bow tie, asymmetric bow tie, and irregular. The symmetric and asymmetric bow tie patterns were the most common topographic pattern (33.0%, and 32.5%, respectively) in our study population, followed by oval (14.5%), irregular (12.5%), and round (7.5%) patterns. The mean corneal astigmatism calculated from videokeratographic data was 0.32 D for round, 0.63 D for oval, 1.16 D for symmetric bow tie, 1.21 D for asymmetric bow tie, and 0.43 D for irregular patterns. There were significant differences among the corneal astigmatic values in the topographic patterns (p < 0.01, Gabriel post hoc test). The distributions of symmetric and asymmetric bow tie patterns were skewed toward greater amounts of corneal astigmatism. In conclusion, the results of this study demonstrate the relationship between topographic patterns and corneal astigmatism and should provide one possible normal standard for corneal topography in Korean adults.

Adult↗