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PubMed1994

A phylogenetic analysis of soldier evolution in the aphid family Hormaphididae.

Aphid soldiers, altruistic larvae that protect the colony from predators, are an example of highly social behaviour in an insect group with a natural history different from the eusocial Hymenoptera and Isoptera. Aphids therefore allow independent tests of theory developed to explain the evolution of eusociality. Although soldiers have been discovered in five tribes from two families, the number and pattern of origins and losses of soldiers is unknown due to a lack of phylogenetic data. Here I present a mtDNA based phylogeny for the Hormaphididae, and test the hypothesis that soldiers in the tribe Cerataphidini produced during two points in the life cycle represent independent origins. The results support this hypothesis. In addition, a minimum of five evolutionary events, either four origins and one loss or five origins, are required to explain the distribution of soldiers in the family. The positions of the origins and losses are well resolved, and this phylogeny provides an historical framework for studies on the causes of soldier aphid evolution.

Animals↗
PubMed2004

Dynamics and stability of vortex-antivortex fronts in type-II superconductors.

The dynamics of vortices in type-II superconductors exhibit a variety of patterns whose origin is poorly understood. This is partly due to the nonlinearity of the vortex mobility, which gives rise to singular behavior in the vortex densities. Such singular behavior complicates the application of standard linear stability analysis. In this paper, as a first step towards dealing with these dynamical phenomena, we analyze the dynamical stability of a front between vortices and antivortices. In particular, we focus on the question of whether an instability of the vortex front can occur in the absence of a coupling to the temperature. Borrowing ideas developed for singular bacterial growth fronts, we perform an explicit linear stability analysis which shows that, for sufficiently large front velocities and in the absence of coupling to the temperature, such vortex fronts are stable even in the presence of in-plane anisotropy. This result differs from previous conclusions drawn on the basis of approximate calculations for stationary fronts. As our method extends to more complicated models, which could include coupling to the temperature or to other fields, it provides the basis for a more systematic stability analysis of nonlinear vortex front dynamics.

Journal Article↗
PubMed2000

Femoral surface strain in intact composite femurs: a custom computer analysis of the photoelastic coating technique.

Understanding how forces are distributed through the proximal femur has many clinical applications for surgeons, researchers, and prosthetic designers. A new system for two-dimensional analysis of femoral surface strain was developed and applied to intact composite femurs. The photoelastic coating method was used to resolve the surface strain under axial loading, and strain analysis was performed using digital imaging of the strain patterns and original computer programs. The technique provides qualitative and quantitative data that describes overall femoral surface strains more completely than previous point analysis and strain gauge techniques. Results from repeated testing found the photoelastic process, computer imaging and computer analysis of strain areas to be statistically repeatable.

Biomechanical Phenomena↗
PubMed2004

Regenerating MR tagged images using harmonic phase (HARP) methods.

Magnetic resonance tagging has proven useful in the visualization and quantification of cardiac motion. Traditionally, tags are designed to have crisp geometric profiles in order to enhance both visualization and detection of tags. Recent image acquisition and analysis methods, however, have been designed to exploit sinusoidal tag profiles. This paper presents a method based on harmonic phase (HARP) concepts to synthesize tag lines that have both crisp profiles and alternative orientations from the original sinusoidal patterns. Results are demonstrated on images acquired with SPAMM, CSPAMM, and fast-HARP pulse sequences.

Algorithms↗
PubMed2006

Craniofacial malformations: intrinsic vs extrinsic neural crest cell defects in Treacher Collins and 22q11 deletion syndromes.

The craniofacial complex is anatomically the most sophisticated part of the body. It houses all the major sensory organ systems and its origins are synonymous with vertebrate evolution. Of fundamental importance to craniofacial development is a specialized population of stem and progenitor cells, known as the neural crest, which generate the majority of the bone, cartilage, connective and peripheral nerve tissue in the head. Approximately one third of all congenital abnormalities exhibit craniofacial malformations and consequently, most craniofacial anomalies are considered to arise through primary defects in neural crest cell development. Recent advances however, have challenged this classical dogma, underscoring the influence of tissues with which the neural crest cells interact as the primary origin of patterning defects in craniofacial morphogenesis. In this review we discuss these neural crest cell interactions with mesoderm, endoderm and ectoderm in the head in the context of a better understanding of craniofacial malformations such as in Treacher Collins and 22q11 deletion syndromes.

Chromosome Deletion↗
PubMedDate not supplied

White and West Indian infants in London: development from birth to 44 weeks of age.

Fifty white and 50 West Indian babies were examined on four occasions between birth and the age of 10 months. The West Indian babies were significantly advanced over the white babies when newborn, but by 6 weeks of age were losing their advantage; there were no significant differences at 6 months and 10 months of age. The ethnic origin, growth pattern, feeding customs and relevant socioeconomic factors were considered and the implications discussed.

Black People↗
PubMed1985

The organization of cell populations within lymph nodes: their origin, life history and functional relationships.

The normal lymph node comprises a superficial cortex, a deep cortex or paracortex and a medulla. In each of these regions there are three kinds of spaces: an intralymphatic space, an intravascular space and an extravascular space or interstitium. Both the vascular endothelium and the lymphatic endothelium are specialized in these different regions. The cell types in lymph nodes comprise lymphoid cells, accessory or non-lymphoid cells and stromal cells, and within these cell types a number of different sub-types can now be identified by means of enzyme- and immunocytochemistry. Based predominantly on experimental studies, the origin, migratory patterns, localization, inter-relationships and interactions between these various cells are reviewed.

Animals↗
PubMed2005

Phylogeography, genetic structure, and diversity in the dhole (Cuon alpinus).

The Asiatic wild dog or dhole was once very widely distributed across Asia but now has a very fragmented range. In this first genetic study of this little-known species, we obtained information on genetic diversity, phylogeography, and social structure using both mitochondrial control region sequencing and microsatellite genotyping of noninvasive faecal samples from wild populations, as well as from museum and captive samples. A pattern largely consistent with isolation by distance across the Asian mainland was observed, with no clear subspecies distinctions. However, two major phylogeographical groupings were found across the mainland, one extending from South, Central, and North India (south of the Ganges) into Myanmar, and the other extending from India north of the Ganges into northeastern India, Myanmar, Thailand and the Malaysian Peninsula. We propose a scenario involving glaciation events that could explain this pattern. The origin of the dhole populations in Sumatra and Java is enigmatic and requires further study. Very low levels of genetic diversity were observed among wild dholes from Baluran National Park in Java, Indonesia, but in contrast, high levels were observed in Mudumalai Wildlife Sanctuary in South India.

Animals↗
PubMedDate not supplied

Immunocytochemical characterization of the macrophage and lymphocyte infiltrate in the brain in six cases of human encephalitis of varied aetiology.

Monoclonal antibodies that react with various macrophage and lymphocyte sub-populations have been applied to acetone-fixed cryostat sections of brains from six cases of human meningo-encephalitis (two cases of subacute sclerosing panencephalitis, two cases of allergic encephalitis, one case of suspected entero-virus meningo-encephalitis and one case of meningo-encephalitis of undetermined origin). The patterns of inflammatory cell response that these antibodies reveal is described and discussed in comparison with published descriptions of the corresponding cell types found in the brain in Japanese encephalitis, herpes simplex encephalitis and multiple sclerosis. In general, in the acute phases of inflammatory central nervous system diseases, T lymphocytes and macrophages predominate in the parenchyma, while the early phases of a B cell response take place in perivascular spaces.

Adolescent↗
PubMed1996

Use of ICD-9-CM codes in the estimation of alcohol-involved injury: search for a surrogate II.

This study presents a follow-up analysis of 22,427 injury cases drawn from the California Regional Trauma Registry. Whereas the earlier analysis developed a surrogate for alcohol-involved injuries using E-codes as reflective of injury type, this analysis explores the possibility of using ICD-9-CM diagnosis codes that have a longer history and are available in more jurisdictions. Findings reported herein indicate that the original demographic patterns predicting testing and alcohol involvement patterns were maintained in ICD-9-CM diagnostic code-based models. Moreover, although variables representing demographic background, time of day, and day of week clearly were the most powerful model predictors, ICD-9-CM diagnostic codes reflecting physician assessment that the patient had a chronic alcohol problem did improve the fit of models, and thus provide additional information concerning testing and blood alcohol concentration patterns. In contrast, ICD-9-CM diagnostic codes reflecting the specific nature of the injury, although statistically significant, explained little additional variability in alcohol involvement. Nevertheless, the overall model did accurately classify approximately 75% of those in the sample for whom blood alcohol concentration status information was available, suggesting its appropriateness for surrogate development.

Adolescent↗
PubMed2002

Making up for lost time: the experience of separation and reunification among immigrant families.

In the United States today, one-fifth of the nation's children are growing up in immigrant homes. In the process of migration, families undergo profound transformations that are often complicated by extended periods of separation between loved ones--not only from extended family members, but also from the nuclear family. Though many families are involved in these transnational formulations, there has heretofore been little sense of the prevalence of these forms of family separations, nor of the effects on family relations. Further, such research has generally been conducted with clinical populations using Western theoretical frameworks and perspectives of families, limiting its applicability to immigrant families. The data presented in this article are derived from a bicoastal; interdisciplinary study of 385 early adolescents originating from China, Central America, the Dominican Republic, Haiti, and Mexico. Findings from this study indicate that fully 85% of the participants had been separated from one or both parents for extended periods. While family separations are common to all country-of-origin groups, there are clear differences between groups in lengths of separations as well as people from whom the youth are separated. Descriptive statistics of country-of-origin prevalence, patterns, and outcomes are presented. Results of analyses of variance indicate that children who were separated from their parents were more likely to report depressive symptoms than children who had not been separated. Further, qualitative data from youth, parent, and teacher perspectives of the experience of separation and reunification provide evidence that the circumstances and contexts of the separations lead to a variety of outcomes. We conclude with a discussion of attenuating and complicating factors family therapists should consider in the assessment and treatment of immigrant families.

Adolescent↗
PubMed1993

Brief family therapy with alcohol-dependent men in Trinidad and Tobago.

This study--the first of its kind in the English-speaking Caribbean--investigated the efficacy of modified brief family therapy in the treatment of alcoholism. Thirty men were treated with family therapy and milieu therapy and compared with 30 sex- and age-matched patients treated with milieu therapy alone. Follow-up over a period of 1 year showed significant levels of improvement in those treated with family therapy. The treatment group did not revert to their original drinking pattern. This can be attributed to family therapy. Family therapy was brief and involved seeing all significant members for 3 sessions, each session lasting 90 min. The role of family therapy and importance of culture in management of these patients are discussed. Our study confirms that a time-limited problem-solving family therapy approach is of use in these ethnic groups.

Adult↗
PubMed1995

Early re-feeding in the management of acute diarrhoea in infants of 0-1 year of age.

We compared early versus late re-feeding in the management of acute diarrhoea in the first year of life. In the study group (73 groups) breast feeding was resumed or early re-feeding was performed in non-breast-fed infants, so that the feeding regimen used prior to the onset of the disease was reached within 2-3 days. In the control group (49 patients) late re-feeding was performed so that the infants returned to their original feeding pattern after 4-6 days. there were no significant differences between the two groups in the number of stools and stool output per day, or in the duration of the disease. No weight gain or loss during the diet was noted more frequently in the late re-feeding group (67.2% versus 2.3.4%). This study confirms the favourable effect on body weight of early re-feeding in the management of acute diarrhoea.

Acute Disease↗
PubMed1976

Re-innervation of twitch and slow muscle fibres of the frog after crushing the motor nerves.

1. The conduction velocities of individual motor axons innervating twitch and slow muscle fibres of the frog were determined by intracellular recording of junctional potentials elicited by stimulating the motor nerves at two different points. 2. In normal pyriformis muscles twitch and slow fibres were found to be innervated by two distinct populations of motor axons. Twitch fibre axons conducted at 10-18-7 m/sec, while the conduction velocities of slow fibre axons ranged from 0-5 to 5 m/sec (at 7-9 degrees C). The thresholds for electrical stimulation were significantly lower in the fast than in the slow axons population. 3. Following denervation by crushing the sciatic nerve fast axons which re-innervated the muscle had lower conduction velocities than normal but could still be identified. These lower conduction velocities were measured proximal to the site of the crush and did not recover over a period of 446 days. 4. Fast motor axons regenerated more quickly than slow axons and re-innervated twitch as well as slow muscle fibres non-selectively. About 1 month later slow axons re-established synaptic contacts with slow (and some twitch) muscle fibres. Simultaneous re-innervation by fast and slow motor axons was occasionally observed in slow muscle fibres. Finally, the slow muscle fibres were innervated by slow axons only, while synapses of fast axons could no longer be found in this type of muscle fibre. 5. Action potentials were observed in denervated as well as in re-innervated slow muscle fibres; they disappeared as re-innervation progressed. 6. It is concluded that non-selective re-innervation of slow muscle fibres is present in the frog; it is, however, a transient phenomenon followed by restoration of the original innervation pattern.

Action Potentials↗
PubMed1984

Post-synaptic inhibition of bulbar inspiratory neurones in the cat.

Stable intracellular recordings from thirty-six bulbar inspiratory neurones revealed three centrally originating, rhythmic patterns of synaptic inhibition (i.p.s.p.s). (i) A declining pattern of i.p.s.p.s accompanying the early stages of inspiration (early inspiratory inhibition) was identified in a total of twenty neurones representing examples of each of the functional classes of bulbar neurones examined, i.e. six R alpha- and two R beta-neurones of the dorsal respiratory group and twelve R alpha-neurones of the ventral respiratory group. (ii) A transient pattern of i.p.s.p.s just preceding or coinciding with the cessation of inspiration (late inspiratory inhibition) was present in the remaining sixteen neurones which were tested, representing six R alpha-neurones and three R beta-neurones of the dorsal respiratory group and seven R alpha-neurones of the ventral respiratory group. (iii) An augmenting pattern of expiratory i.p.s.p.s was present in all thirty-six neurones. Late inspiratory and expiratory i.p.s.p.s in the same neurones showed a similar time course of reversal when chloride was injected or allowed to diffuse into the cells and were associated with similar increases in input conductance. Both patterns of i.p.s.p.s appear to arise at or close to the cell soma. Early inspiratory i.p.s.p.s required a relatively longer period of chloride injection for reversal to be accomplished. Input conductance changes were either absent or smaller than those associated with late inspiratory or expiratory inhibition. These i.p.s.p.s appear to arise at more distal dendritic sites. These patterns of i.p.s.p.s are discussed in relation to the mechanisms shaping the growth of central inspiratory activity, bringing this activity to an end, and suppressing its redevelopment during expiration.

Animals↗
PubMed1998

[Analysis of transmission of Burkholderia cepacia isolates in an intrahospital by randomly amplified polymorphic DNA-PCR method].

Strains of Burkholderia cepacia isolated in our hospital from November 1995 to September 1996 were classified with randomly amplified polymorphic DNA-PCR (RAPD-PCR) and conventional biochemical tests (ID test.NF-18, API20NE, and Neg Combo 4J kit), and intrahospital isolates of B. cepacia were analysed. During the period 28 strains from inpatients and 2 from medical apparatus were isolated. Twenty four of 28 (85.7%) were from sputum. In 1996 from January to February, 20 strains were detected from 8 inpatients, and two strains were from the nebulizers at the Trauma and Critical Care Center (TCC). With typing of B. cepacia by conventional methods no epidemiological relations among isolates were found. However, DNA patterns of original isolates from the nebulizers at TCC by RAPD-PCR were identical with those of isolates in sputa from patients in other wards who had stayed at TCC, indicating that TCC was an initial source of transmission and the strain was transmitted with the patients to the wards. These results suggest that RAPD-PCR method might be a useful tool to analyse an epidemiological survey for intrahospital transmission of isolate.

Burkholderia Infections↗
PubMed1979

The effect of timing errors on the intelligibility of deaf children's speech.

The purpose of this study was to quantify the effect of timing errors on the intelligibility of deaf children's speech. Deviant timing patterns were corrected in the recorded speech samples of six deaf children using digital speech processing techniques. The speech waveform was modified to correct timing errors only, leaving all other aspects of the speech unchanged. The following six-stage approximation procedure was used to correct the deviant timing patterns: (1) original, unaltered utterances, (2) correction of pauses only, (3) correction of relative timing, (4) correction of absolute syllable duration, (5) correction of relative timing and pauses, and (6) correction of absolute syllable duration and pauses. Measures of speech intelligibility were obtained for the original and the computer-modified utterances. On the average, the highest intelligibility score was obtained when relative timing errors only were corrected. The correction of this type of error improved the intelligibility of both stressed and unstressed words within a phrase. Improvements in word intelligibility, which occurred when relative timing was corrected, appeared to be closely related to the number of phonemic errors present within a word. The second highest intelligibility score was obtained for the original, unaltered sentences. On the average, the intelligibility scores obtained for the other four forms of timing modification were poorer than those obtained for the original sentences. Thus, the data show that intelligibility improved, on the average, when only one type of error, relative timing, was corrected.

Adolescent↗
PubMed1986

Pure-tone pitch anomalies. II. Pitch-intensity effects and diplacusis in impaired ears.

Pitch-intensity functions and psychophysical tuning curves (PTC's) were measured in ten listeners with sensorineural impairments of presumed cochlear origin. Masking patterns, frequency jnd's, diplacusis measurements, and octave adjustments were also obtained for selected conditions in selected listeners. The results showed a tendency for increased frequency jnd's and increased pitch-matching variability in frequency regions where frequency resolution, as determined by PTC Q10 estimates, was degraded. The results also showed exaggerated pitch-level effects, both in regions where frequency resolution was degraded and, in many cases, in regions where thresholds and frequency resolution were apparently normal. The usual manifestation of exaggerated pitch-level effect was an abnormally large negative pitch shift with increasing level, particularly at low frequencies. The limited data from diplacusis measurements and octave adjustments suggest that the exaggerated negative pitch shifts are the consequence of a large increase in pitch at low stimulus levels which "recruits" at higher levels. These results are difficult to explain with simple tonotopic models, or presently formulated temporal models, of pure-tone pitch encoding.

Acoustic Stimulation↗