Preparation of a protein micro-array using a photo-reactive polymer for a cell-adhesion assay

A protein micro-array, called a "cell chip" was constructed by using a photo-reactive polymer for a cell-adhesion assay. Various amounts of albumin or fibronectin were covalently immobilized on a polystyrene dish using a micro-spotter with a dip pen. First, poly(acrylic acid) carrying azidophenyl groups was synthesized as the photo-reactive polymer. Secondly, the aqueous solution of a photo-reactive polymer (several nanoliters) was cast using the dip pen of the micro-spotter and dried in air. Subsequently, aqueous solutions of proteins were cast on the same place using the micro-spotter. After drying, the dish was irradiated with ultraviolet light. Finally, the immobilization was confirmed by staining with a dye. The immobilization was stable even after washing with Tween-20. The protein-immobilized area depended on the manipulation of the micro-spotter and the size of the dip pen. Subsequently, cell adhesion on the photo-immobilized protein micro-array was investigated. The adhesion behavior of cells depended on the kind of immobilized proteins and the kind of cells. The protein micro-array will be useful for cell diagnosis and for the selection of biomaterials to regulate cell behavior.     

Sprinting on a running track: a rare cause of a Lisfranc dislocation

We present a case report of a young man who sustained a serious foot injury while sprinting in a straight line. We discuss the management of these injuries and emphasise the importance of a high index of suspicion amongst orthopaedic, casualty and radiology trainees.     

Once in a lifetime: a case of a pineal tumour

This paper describes the case of a 14-year-old boy who presented to his general practitioner with a history of headaches and visual problems. Investigations subsequently revealed that he had a pineal tumour. The management of the patient is described and this rare condition discussed.     

Writing through a robot: a proof of concept for a brain-machine interface

This paper describes a non-invasive human brain-actuated robotic arm experiment, which allows remote writing. In the local environment, the participant decides on an arbitrary word to transmit. A mental speller interface is then used to select the letters. A robot arm placed in the remote environment writes the word on a whiteboard in real time. A multidisciplinary framework such as the one presented here exemplifies a class of interactive applications with possible relevance in a variety of fields, such as entertainment and clinical environments.     

Silicone lymphadenopathy mimicking a lymphoma in a patient with a metatarsophalangeal joint prosthesis

With lymph node enlargement, the possibility of a malignant process such as metastatic carcinoma or lymphoma needs to be excluded. This report describes a 47 year old woman with inguinal lymph node enlargement initially suspicious for lymphoma. Fine needle aspiration findings favoured reactive hyperplasia, but a malignant process could not be excluded. The final histological diagnosis was a foreign body granulomatous inflammatory response as a result of regionally disseminated silicone particles from an over looked metatarsophalangeal joint prosthesis. Because of the large number of joint prostheses world wide, it should be kept in mind that migration of wear particles can create granulomatous inflammation and node enlargement.     

Molecular characterization of a strain of group a streptococcus isolated from a patient with a psoas abscess

We report the first case of a primary group A streptococcus (GAS) psoas abscess in a 31-year-old woman. The psoas abscess was preceded by an episode of acute pharyngitis. The M-protein gene (emm) and streptolysin S structural gene (sagA) were present in the isolate, with no significant amino acid differences from previously described sequences of M1 GAS isolates. Multilocus sequence typing (MLST) showed that the isolate belonged to MLST sequence type (MLST-ST) 28, the predominant MLST-ST associated with invasive disease caused by M1 isolates.     

Shear Augmented Dispersion of a Solute in a Casson Fluid Flowing in a Conduit

The unsteady dispersion of a solute in a Casson fluid flowing in a conduit (pipe/channel) is studied using the generalized dispersion model of Gill and Sankarasubramanian. With this approach, the entire dispersion process is described appropriately in terms of a simple diffusion process with the effective diffusion coefficient as a function of time, in addition to its dependence on the yield stress of the fluid. The results are accurate up to a first approximation for small times, but verified with Sharp to be exact for large times. The model brings out mainly the effect of yield stress, or equivalently, the plug flow region on the overall dispersion process. It is found that the rate of dispersion is reduced (i.e., the effective diffusivity decreases) due to the yield stress of the fluid, or equivalently, the plug flow region in the conduit. Also, the effective diffusivity increases with time, but eventually attains its steady state value below a critical time [0.48(a²/D_m) for dispersion in a pipe and 0.55(a²/D_m) for dispersion in a channel—the critical transient time for a Newtonian fluid—where a is the radius of the pipe and D_m is the molecular diffusivity]. At steady state, for dispersion in a pipe with the plug flow radius one tenth of the radius of the pipe, the effective diffusivity is reduced to about 0.78 times of the corresponding value for a Newtonian fluid at equivalent flow rates; for dispersion in a channel, the reduction factor is about 0.73 confirming the earlier result of Sharp. Further, the location of the center of mass of a passive species over a cross section is found to remain unperturbed during the course of dispersion and for different values of the plug flow parameter (i.e., the yield stress of the fluid). The study can be used as a starting first approximate solution for studying the dispersion in the cardiovascular system or blood oxygenators. © 2000 Biomedical Engineering Society. PAC00: 8719Uv, 4760+i, 8350Nj, 8370Hq, 8715Vv, 8710+e, 4755Kf     

Running a weight control group: experiences of a psychologist and a general practitioner

A weight control group is described, led jointly by a general practitioner and a clinical psychologist. Approaches employed included dietary advice, behavioural advice, and group support. Of the original 16 members (including one group leader), seven dropped out at an early stage and the reasons for this are discussed. All members were re-weighed at intervals up to 18 months after the beginning of the six-month intensive period. They were also interviewed by a psychological research worker a year after the start of the group. The results suggest that a combined dietetic and psychological approach to weight control is of value.     

Modelling a parasystolic rhythm in a heart-transplant patient

A parasystole from a heart-transplant patient is analysed using a beat-to-beat RR interval time series obtained from an electrocardiogram (ECG). The dysrhythmia, resulting from the co-existence of two pacemakers, the sinus node and an ectopic focus, presents distinctive regular patterns, with transitions from one pattern to another occurring abruptly. It is shown that the parasystolic rhythm can be simulated by a model involving two oscillators firing at fixed rates, under the restriction that neither is allowed to fire during the other's refractory period. It is found that the structure of the generated RR time series is essentially determined by the ratio of the periods of the two oscillators. In the case of a heart-transplant patient with a small heart-rate variability as a result of heart denervation, the model predicts the RR intervals with an error of less than 6% for an 80-beat sequence. From a physiological point of view, the results imply that the interaction between the two pacemakers in the heart is fairly weak, and hence the parasystole observed in the heart-transplant patient can be modelled as pure parasystole.     

Modelling a parasystolic rhythm in a heart-transplant patient

A parasystole from a heart-transplant patient is analysed using a beat-to-beat RR interval time series obtained from an electrocardiogram (ECG). The dysrhythmia, resulting from the co-existence of two pacemakers, the sinus node and an ectopic focus, presents distinctive regular patterns, with transitions from one pattern to another occurring abruptly. It is shown that the parasystolic rhythm can be simulated by a model involving two oscillators firing at fixed rates, under the restriction that neither is allowed to fire during the other's refractory period. It is found that the structure of the generated RR time series is essentially determined by the ratio of the periods of the two oscillators. In the case of a heart-transplant patient with a small heart-rate variability as a result of heart denervation, the model predicts the RR intervals with an error of less than 6% for an 80-beat sequence. From a physiological point of view, the results imply that the interaction between the two pacemakers in the heart is fairly weak, and hence the parasystole observed in the heart-transplant patient can be modelled as pure parasystole.     

Sleepiness as a state-trait phenomenon,comprising both a sleep drive and a wake drive

In this paper it is proposed to extend the classical models of sleepiness in two ways. Firstly, the role of a wake drive, besides a sleep drive, in determining sleepiness is emphasised. Although this has already been suggested in literature and convincing arguments can be found, it is not generally accepted. Secondly, we argue to incorporate trait aspects of sleepiness or a long-term person-specific level of sleepiness, besides short-term changes of sleepiness or 'state-sleepiness'. Shortly, a conceptualisation of sleepiness in which situational wake drive and sleep drive modify a basal level of both wake drive and sleep drive, is proposed. It implies that sleepiness can result from essentially different factors involved: a chronic condition or an acute state of either a high level of sleep drive, a low level of arousal or a combination of both. This is illustrated in a working model and potential assessment tools for the wake drive and state versus trait sleepiness are discussed.     

Is a stimulus conveying task-relevant information a sufficient condition to elicit a stimulus-preceding negativity?

Movement-preceding and stimulus-preceding negativities were recorded when a movement was followed by one of three informative visual stimuli. The meaning of the visual stimulus alternated between (a) conveying a task-relevant instruction about a subsequent time production task and (b) providing feedback (knowledge of results) about performance on the current time production task. In a control condition, premovement and postmovement scalp potentials were recorded when subjects made the same movements but in a voluntary, self-paced manner. Under all conditions, movements were preceded by a movement-preceding negativity, and neither the amplitude nor the lateral asymmetry of this negativity was affected by the subsequent presentation of either kind of informative stimulus. When the movement was followed by a stimulus conveying knowledge of results, the negativity in the postmovement epoch was enhanced, but this enhancement was not evident in epochs preceding instruction stimuli. We conclude that not all task relevant stimuli elicit a stimulus-preceding negativity, and we provide a functional interpretation of this negativity in terms of emotional anticipation and the contingency of the stimulus on a previous event.     

Triploidy arising from a first meiotic non-disjunction in a mother carrying a reciprocal translocation.

We report on a 22 year old mother, a carrier of a 6;14 balanced reciprocal translocation, who aborted a triploid conceptus carrying a similar translocation. We showed the maternal origin of this triploidy, after non-disjunction at meiosis I. The phenotypic expression as a non-molar pregnancy, the contribution of the maternal translocation, and possible aetiological factors of triploidy are discussed.     

Application of a PDMS microstencil as a replaceable insulator toward a single-use planar microelectrode array

Here we present a novel idea for a replaceable insulator, and thus advance toward the goal of a single-use planar microelectrode array (MEA) for the study of electrogenic tissues. The concept of a replaceable insulator is motivated by insulator degradation after repeated usage of an MEA. Instead of fabricating a more durable insulator for repeated MEA usage, we propose replacing the insulator and effectively producing a fresh MEA for each experiment. We chose a polydimethylsiloxane (PDMS) microstencil as a candidate for the replaceable insulator as it is biocompatible, shows reversible adhesion to surfaces, and can be easily and controllably fabricated. As a proof-of-concept, we demonstrate two applications using microstencils: the rejuvenation of an old MEA and the fabrication of a single-use MEA. These MEAs were tested with dissociated neural cell cultures and neural recordings were performed at 14 days in vitro. Inexpensive and quick supply of insulators with micrometer-sized holes provides a way of constructing an MEA that can be treated as a disposable component in high throughput cell-based biosensor applications.     

Multicentric reticulohistiocytosis: a report of a case and a review of the pathology

A case of multicentric reticulohistiocytosis (MR) in a 24-yr-old woman is presented. MR is a rare disorder characterized by progressive polyarthropathy and a papulo-nodular skin rash. The diagnosis was established by histological examination of biopsies of erythematous nodules on the fingers which showed circumscribed collections of large mononuclear cells and multinucleate giant cells in the reticular dermis. These were embedded in a fine network of mature fibrous tissue with a scanty lymphocytic infiltrate. Histochemical, immunopathological and ultrastructural investigations confirmed that the large mononuclear cells had the properties of macrophages. The histopathological features of MR are reviewed in the light of current knowledge of macrophage physiology, and evidence for lymphocyte-histiocyte interactions in the pathogenesis of this bizarre granulomatous disorder is presented.     

Cytogenetic analysis of a mature teratoma and a yolk sac tumor component of a late relapse of a disseminated testicular nonseminoma.

We report on the cytogenetics of a primary testicular nonseminoma, a residual mature teratoma after remission-induction chemotherapy, and a late relapse after 9 years of follow-up, in one patient. The late relapse was composed of a mature teratoma and a yolk sac tumor component. Cytogenetic comparison of the different tumors shows that progression of primary testicular nonseminoma to residual mature teratoma and to a late-relapse lesion is accompanied by net loss of chromosomes. In addition, our findings may suggest that transformation to viable cancer in a late-relapse lesion is accompanied by further chromosomal losses.     

Developing a framework for development: a discussion

A multitude of scientific disciplines study the development of behavior. Their use of different methodological and conceptual approaches makes integration of findings difficult. In a symposium at the 38th Annual Meeting of the International Society for Developmental Psychobiology in Washington DC, the question was discussed if a general theory of development could unify the field. The three participants explain their views and discuss the possibility of a theoretical framework for development.     

Analysis of a clinical case from a Spanish perspective

In Spain, psychological treatment is offered in both public and private settings. The public Mental Health Units are part of Community Health Centers, where psychiatric and psychological treatments are offered free of charge. However, most professionals offering psychotherapy work in the private sector. In any Spanish city, a great number of private clinical psychologists offer psychotherapy for a variety of clinical disorders and different ages. The case of Mrs. A illustrates many of the key features of psychotherapy in Spain. She would probably be treated in a Health Center. A family physician would evaluate her mental status and establish a pharmacological treatment. If the patient's condition did not improve, the physician would refer her to a specialist in mental health, either a psychiatrist (using pharmacological treatments), in most cases, or in a few cases, a clinical psychologist (using mainly cognitive-behavioral treatment).     

Abdominal actinomycosis associated with a sigmoid colon perforation in a patient with a ventriculoperitoneal shunt

Abdominal actinomycosis causing hydronephrosis in a patient with a ventriculoperitoneal shunt is very rare. A 27- year-old female patient was admitted complaining of lower abdominal pain. She had undergone ventriculoperitoneal shunt surgery 10 years ago. Abdominal Ultrasonography and a CT scan demonstrated an inflammatory mass in the lower left quadrant of the abdomen causing obstructive hydroureter and hydronephrosis. Laparotomy revealed a diffusely infiltrating mass involving the small bowel, mesentery, and sigmoid colon, and a 1cm perforation in the sigmoid colon. Actinomycosis was diagnosed upon histological examination. After treatment with antibiotics and surgery, the patient's condition improved.     

Coexistence of a Meckel's diverticulum and a urachal remnant

Meckel's diverticulum, which is a remnant of the omphalomesenteric or vitelline duct, is the most common congenital abnormality of the gastrointestinal system. Urachal abnormalities, resulting from anomalous urogenital development, are not observed frequently and case reports are mainly represented in literature. The presence of these two congenital anomalies together is a very rare pathology. Complications arising from a Meckel's diverticulum or urachal remnant may clinically mimic acute appendicitis and other surgical pathologies. We report on a patient who underwent surgery for acute appendicitis when it was discovered that the symptoms were produced by a perforated Meckel's diverticulitis. In the course of the surgery, a urachal remnant was found to coexist with the diverticulum.