Feeding ability in Rett syndrome

Feeding abilities in 20 individuals with Rett syndrome aged 1 1/2 to 33 years were investigated by history and clinical assessment during a meal, followed by videofluoroscopy of feeding. All were shown to have reduced movements of the mid and posterior tongue, with premature spillover of food and liquid from the mouth into the pharynx. They also showed delayed pharyngeal swallow, but otherwise pharyngeal problems were minimal. These findings were noted to be similar to those in Parkinson's disease. Those individuals with the most general neurological impairment tended to have the worst feeding problems and were smaller and malnourished.

Comparative review of techniques for recording respiratory events at rest and during deglutition

The coordination between swallowing and respiration is essential for safe feeding, and noninvasive feeding-respiratory instrumentation has been used in feeding and dysphagia assessment. Sometimes there are differences of interpretation of the data produced by the various respiratory monitoring techniques, some of which may be inappropriate for observing the rapid respiratory events associated with deglutition. Following a review of each of the main techniques employed for recording resting, pre-feeding, feeding, and post-feeding respiration on different subject groups (infants, children, and adults), a critical comparison of the methods is illustrated by simultaneous recordings from various respiratory transducers. As a result, a minimal combination of instruments is recommended which can provide the necessary respiratory information for routine feeding assessments in a clinical environment.

Effortful touch with minimum movement: revisited

The ecological static moment-torque model proposed by C. Carello, P. Fitzpatrick, I. Domaniewicz, T.C. Chan, and M.T. Turvey (1992) does not uniquely explain the perception of rod length by static holding. Guided by a mechanical analysis of the gravitational forces and torques produced in the hand as it statically holds rods of different lengths and materials at different orientations, we offer 2 additional theoretical explanations, the force-torque and weight-percept models. Experiment 1 demonstrates that all 3 models predict perceived rod length with considerable success. Experiment 2 provides clear experimental support for the force-torque and weight-percept models over the static moment-torque model. Experiment 3 pits the former 2 models against each other. Current results favor the weight-percept model. Implications for theories of haptic weight perception and design of a new tactile sensor are also considered.

Transcriptional regulator of programmed cell death encoded by Caenorhabditis elegans gene ces-2

The ces (for cell-death specification) genes of the nematode Caenorhabditis elegans control the cell-death fate of individual cell types and are candidates for being the regulators of an evolutionarily conserved general pathway of programmed cell death. Here we present what we believe is the first molecular characterization of a ces gene. We cloned the gene ces-2, which is required to activate programmed cell death in the sister cells of the serotoninergic neurosecretory motor (NSM) neurons, and found that ces-2 encodes a basic region leucine-zipper (bZIP) transcription factor. The CES-2 protein is most similar to members of the PAR (proline- and acid-rich) subfamily of bZIP proteins and has DNA-binding specificity like that of PAR-family proteins. An oncogenic form of the mammalian PAR-family protein, hepatic leukaemia factor (HLF), is reported to effect programmed cell death in mammalian cells. On the basis of these observations, we suggest that some CES-2/PAR family transcription factors are evolutionary conserved regulators of programmed cell death.

Effortful touch with minimum movement: revisited

The ecological static moment-torque model proposed by C. Carello, P. Fitzpatrick, I. Domaniewicz, T.C. Chan, and M.T. Turvey (1992) does not uniquely explain the perception of rod length by static holding. Guided by a mechanical analysis of the gravitational forces and torques produced in the hand as it statically holds rods of different lengths and materials at different orientations, we offer 2 additional theoretical explanations, the force-torque and weight-percept models. Experiment 1 demonstrates that all 3 models predict perceived rod length with considerable success. Experiment 2 provides clear experimental support for the force-torque and weight-percept models over the static moment-torque model. Experiment 3 pits the former 2 models against each other. Current results favor the weight-percept model. Implications for theories of haptic weight perception and design of a new tactile sensor are also considered.

The fog-3 gene and regulation of cell fate in the germ line of Caenorhabditis elegans

In the nematode Caenorhabditis elegans, germ cells normally adopt one of three fates: mitosis, spermatogenesis or oogenesis. We have identified and characterized the gene fog-3, which is required for germ cells to differentiate as sperm rather than as oocytes. Analysis of double mutants suggests that fog-3 is absolutely required for spermatogenesis and acts at the end of the regulatory hierarchy controlling sex determination for the germ line. By contrast, mutations in fog-3 do not alter the sexual identity of other tissues. We also have characterized the null phenotype of fog-1, another gene required for spermatogenesis; we demonstrate that it too controls the sexual identity of germ cells but not of other tissues. Finally, we have studied the interaction of these two fog genes with gld-1, a gene required for germ cells to undergo oogenesis rather than mitosis. On the basis of these results, we propose that germ-cell fate might be controlled by a set of inhibitory interactions among genes that specify one of three fates: mitosis, spermatogenesis or oogenesis. Such a regulatory network would link the adoption of one germ-cell fate to the suppression of the other two.

Dysphagia following strokes: clinical observations of swallowing rehabilitation employing palatal training appliances

A retrospective study was undertaken to evaluate the progress of a group of dysphagic stroke patients for whom a dental prosthesis the Palatal Training Appliance (PTA), was used in the active rehabilitation of the swallowing mechanism. Patients selected were those who had sustained a stroke uncomplicated by other neurological illness, during one 12-month period, and whose dysphagia caused anxiety to the medical staff in the hospital ward. Thirty severely dysphagic stroke patients satisfied these criteria. The study recorded the duration and type of supplementary feeding required during hospitalization. Thirteen patients had evidence of aspiration before the PTA was fitted and 5 afterwards. Seven patients died, but only 1 was recorded as having a febrile illness which may have contributed to the death. At discharge, which averaged 10 weeks after admission, 22 of the 23 survivors were taking an adequate oral diet. It was also noted that almost half of the patients who wore dentures before the cerebrovascular event were unable to control them afterwards, adding to their neurological swallowing difficulties. The fitting of a PTA and correction of unstable dentures appeared to help both motivation and function. The results show an improvement in the rehabilitation of oral feeding compared with previous reports by other authors, who did not use the dental appliance. There did not appear to be any medical contraindication to its use.

Superimposition of analogue data onto a video image: a new technique

There are many tools to aid the clinician in making an accurate medical diagnosis including various imaging techniques and recording analogue signals from the patient. A new, inexpensive method of combining a video image and the instantaneous values of analogue waveforms is described here. The system, TVDATA, is reliable, compact and portable and has been successfully used in various clinical situations. The unit requires a standard video source, such as a camera, a TV monitor, a video recorder and the output from the analogue source or sources. The analogue data are converted into a digital signal and then displayed in a convenient part of the screen as a horizontal bar. Two types of data channel are available--uni- and bidirectional. A number of these channels can be used to record different analogue parameters and an inbuilt octal frame counter assists subsequent review of the video record.

Control of germ cell differentiation in Caenorhabditis elegans

The germline of Caenorhabditis elegans is organized in a linear fashion--the most distal germ cells remain in mitosis, those in the middle enter meiosis and proximal cells differentiate as sperm or oocytes. Two signal transduction pathways control germ cell fates. The glp-1 gene mediates a signal that promotes mitosis and the genes of the sex determination pathway mediate a signal that determines if germ cells will develop as sperm or oocytes. Information from these pathways acts through terminal regulators to specify cell fate. For example, fog-1 and fog-3 are required to initiate spermatogenesis and gld-1 appears to be required to initiate oogenesis. Study of these terminal regulators suggests that the decisions about sexual identity and mitosis are linked in germ cells. We propose a tripartite interaction that forces germ cells to adopt one of only three fates--mitosis, spermatogenesis or oogenesis.

Water diffusion coefficient measurements in the finger by magnetic resonance imaging

Diffusion coefficients of water have been measured in the fingers of humans by magnetic resonance imaging. It was found that the measured diffusion coefficients increased with subject age in certain regions of the finger but that these regions differed between males and females. The observation of an increased diffusion coefficient with age appears to be inconsistent with a direct-hydration model and possible explanations are given using other models. It is conjectured that the measured diffusion coefficient of water increases with age as a result of structural changes to proteins.

The synchronization of respiration and swallow sounds with videofluoroscopy during swallowing

Simultaneous recording of adult subjects sipping small amounts of fluid from a cup have been obtained by videofluoroscopy together with feeding respiratory patterns and swallow sounds from the Exeter Dysphagia Assessment Technique (EDAT). These allowed visual representations of respiration and swallow sounds to be superimposed on a videofluoroscopy recording using a split-screen technique. Sequentially numbered, 1/50 sec, half-frame photographic prints were examined and schematic drawings of the relevant radiographs were made. These were superimposed on to the actual EDAT printed chart of the same swallow event, their exact time relationship with respiration and cervical swallow sounds being preserved. The results allow events in the barium videofluoroscopy to be related to events in the feeding respiratory pattern and swallow sounds recorded by EDAT.

A kinematic technique for describing wrist joint motion: analysis of configuration space plots

This paper describes an experimental method for determining the minimum number of degrees of freedom of a human joint. Application of this technique to the wrist suggests that the normal, intact wrist joint uses only two degrees of freedom to move in a plane that is not aligned with the anatomic planes. The technique may be useful in identifying emerging joint pathologies and in simplifying kinematic models of joint function.

Magnetic resonance imaging manifestations of idiopathic haemochromatosis in the wrist

The magnetic resonance imaging features of the wrist of a patient suffering from the arthropathy of haemochromatosis are presented. It is apparent that the deposition of iron within the bone marrow is focal in origin and may be associated with cyst formation. In addition, changes in serum ferritin levels with treatment suggest that the deposition is irreversible. Studies of two other patients with haemochromatosis without cyst formation in the wrists did not yield similar artefacts, in spite of having high ferritin levels and arthritis.

Dysphagia in cerebral palsy: a comparative study of the Exeter Dysphagia Assessment Technique and a multidisciplinary assessment

Eighteen children with cerebral palsy in a special school, most of whom had feeding difficulties, were studied to compare the diagnostic value of the Exeter Dysphagia Assessment Technique (EDAT) with an exhaustive clinical assessment undertaken by a multidisciplinary team experienced in the diagnosis and treatment of dysphagia of neurological origin. Four feeding skills were assessed by each method independently, viz. anticipation, intraoral sensory perception, oral-motor efficiency, and pharyngeal triggering. Comparison of the two sets of results showed agreement in at least 78% of the assessed skills. The possible reasons for the few discrepancies are discussed. The noninvasive EDAT equipment was easy to use with the children, who had a range of type and severity of cerebral palsy. The test was undertaken in their familiar surroundings and took 15 to 20 min per child. Interpretation of the results showed that EDAT provided a rapid, reliable diagnostic aid which assisted in the assessment of the degree of feeding impairment within each of the four feeding skills tested.

Negative regulators of programed cell death

During animal development many cells undergo programed deaths. Recently, genes that suppress the cell-death program have been described in both vertebrates and invertebrates. These genes play a vital role in regulation of the molecules that kill cells, and disruption of this regulatory process can contribute to disease.

Caenorhabditis elegans gene ced-9 protects cells from programmed cell death

The gene ced-9 of the nematode Caenorhabditis elegans acts to protect cells from programmed cell death. A mutation that abnormally activates ced-9 prevents the cell deaths that occur during normal C. elegans development. Conversely, mutations that inactivate ced-9 cause cells that normally live to undergo programmed cell death; these mutations result in embryonic lethality, indicating that ced-9 function is essential for development. The ced-9 gene functions by negatively regulating the activities of other genes that are required for the process of programmed cell death.

Genes required for the engulfment of cell corpses during programmed cell death in Caenorhabditis elegans

After programmed cell death, a cell corpse is engulfed and quickly degraded by a neighboring cell. For degradation to occur, engulfing cells must recognize, phagocytose and digest the corpses of dying cells. Previously, three genes were known to be involved in eliminating cell corpses in the nematode Caenorhabditis elegans: ced-1, ced-2 and nuc-1. We have identified five new genes that play a role in this process: ced-5, ced-6, ced-7, ced-8 and ced-10. Electron microscopic studies reveal that mutations in each of these genes prevent engulfment, indicating that these genes are needed either for the recognition of corpses by other cells or for the initiation of phagocytosis. Based upon our study of double mutants, these genes can be divided into two sets. Animals with mutations in only one of these sets of genes have relatively few unengulfed cell corpses. By contrast, animals with mutations in both sets of genes have many unengulfed corpses. These observations suggest that these two sets of genes are involved in distinct and partially redundant processes that act in the engulfment of cell corpses.

Two C. elegans genes control the programmed deaths of specific cells in the pharynx

The genes ces-1 and ces-2 control the decisions of two cells in the nematode Caenorhabditis elegans to undergo programmed cell death. Mutations that cause a gain of ces-1 function or a reduction of ces-2 function prevent these cells, the sisters of the two pharyngeal NSM neurons, from dying. These mutations do not affect most other cell deaths. Genetic studies indicate that ces-1 and ces-2 affect the fates of the NSM sisters by regulating the genes required for all programmed cell deaths to occur.

High-resolution magnetic resonance imaging of the interphalangeal joints of the hand

High-resolution magnetic resonance imaging (MRI) of the interphalangeal joints of the fingers is being employed to study arthritis. To facilitate this research, a clear understanding of the structures visualisable by MRI is necessary. A gradient echo (GE) sequence was developed that produced good contrast between cartilage and other joint structures. These detailed images, with an in-plane resolution of 200 x 100 microns, enable resolution of three cartilage zones which can be interpreted as a superficial layer at the cartilage/cartilage interface, an intermediate layer and calcified cartilage in contact with bone; these correlate well with known anatomy. Further analysis of the images indicates that although a chemical shift artifact causes changes in the images at the field strength used (0.5 T), it does not cause enough distortion to necessitate suppression of the effect. Furthermore, the only detectable susceptibility artifact at these low field strengths was a loss of signal in bone trabeculae at the bone/cartilage interface. There is clearly potential in the study of the articular structures, in particular cartilage, in detail, using high-resolution MRI.

The Exeter Dysphagia Assessment Technique

The Exeter Dysphagia Assessment Technique (EDAT) uses noninvasive equipment to record, simultaneously, "feeding respiratory patterns," the time drink entered the mouth, and associated swallow sounds during feeding. The easily portable equipment enabled patients' swallowing ability to be tested, at the bedside if necessary, using a small amount of fruit-flavored drink. The results appear in chart form. EDAT findings from groups of normal subjects aged 2-90 years were compared with those from patients with dysphagia of neurologic origin and normal subjects under experimental feeding conditions. The results revealed maturation of the feeding respiratory pattern in the teenage years and remarkable consistency thereafter. Differences in the recordings between the normal and abnormal subjects were sufficiently marked to allow the findings to be used in the diagnosis of other patients with dysphagia of doubtful neurologic cause. Interpretation of the charts and recorded timings of the oral and pharyngeal stages of swallowing permitted a more accurate identification of sensory nerve, motor nerve, and functional involvement causing dysphagia of neurologic origin and may be used as a guide to the origin of the sensory deficit.

Demonstration of a geode by magnetic resonance imaging: a new light on the cause of juxta-articular bone cysts in rheumatoid arthritis

The magnetic resonance imaging (MRI) features of a rheumatoid arthritic geode are presented. Development of such a cyst from before x ray diagnosis to its coalescence with the wrist joint is described. The evidence suggests that these juxta-articular cysts are not merely an intrusion of the synovial cavity into the bone marrow but start as isolated structures beneath the subchondral bone.

Respiratory patterns associated with swallowing: Part 1. The normal adult pattern and changes with age

Simple, non-invasive equipment was designed to record respiratory patterns associated with swallowing food or drink in young and elderly healthy adults, to compare with neurologically impaired patients who complained of dysphagia. The timing of the entry of the test drink from a spoon into the mouth, the swallow event and respiration were recorded electronically and were presented in chart form. The equipment proved to be easy to use and the results were consistent. All 33 subjects showed a well-defined respiratory pattern, with individual minor variations, but different from the pattern of their resting respiration. The direction of respiration during spoon contact was consistent for each individual and the pharyngeal stage of swallowing was almost always followed by a large expiration. Thus the resting respiration is not simply arrested during swallowing, but is substituted by a different, well-controlled pattern.