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PubMed1983

Vinculin is a component of an extensive network of myofibril-sarcolemma attachment regions in cardiac muscle fibers.

Immunofluorescent staining of bovine and avian cardiac tissue with affinity-purified antibody to chicken gizzard vinculin reveals two new sites of vinculin reactivity. First, vinculin is organized at the sarcolemma in a striking array of rib-like bands, or costameres. The costameres encircle the cardiac muscle cell perpendicular to the long axis of the fiber and overlie the I bands of the immediately subjacent sarcomeres. The second new site of vinculin reactivity is found in bovine cardiocytes at tubular invaginations of the plasma membrane. The frequency and location of these invaginations correspond to the known frequency and distribution of the transverse tubular system in bovine atrial, ventricular, and Purkinje fibers. We do not detect tubular invaginations that stain with antivinculin in avian cardiocytes and, in fact, a transverse tubular system has not been found in avian cardiac fibers. Apparent lateral Z-line attachments to the sarcolemma and its invaginations have been observed in cardiac muscle by electron microscopy in the same regions where we find vinculin. On the basis of these previous ultrastructural findings and our published evidence for a physical connection between costameres and the underlying myofibrils in skeletal muscle, we interpret the immunofluorescence data of this study to mean that, in cardiac muscle, vinculin is a component of an extensive system of lateral attachment of myofibrils to the plasma membrane and its invaginations.

Animals↗

PubMed2006

[Change in the joint line after total knee arthroplasty].

OBJECTIVE: To investigate the change in joint line after knee arthroplasty. METHODS: A total of 43 patients had 25 primary cruciate-retaining total knee replacements (Link Gemini MKII) and 25 rotational knee replacements (Link Endo-Model Rotational Knee System) sacrificing collateral ligaments and cruciate ligaments. Lateral radiographs were made both preoperatively and postoperatively. The change in the relative position of the joint line preoperatively and postoperatively was defined as the difference between the perpendicular distance from the weight-bearing surface of the tibial plateau to the tibial tubercle of the natural tibia (JL) and perpendicular distance from the weight-bearing surface of the prosthetic tibial component to the tibial tubercle (JL'). This distance was JL'-JL. The statistical differences between 2 groups were analyzed. RESULTS: The distance of JL'-JL was 2.0 mm (-1.3 - 7.2 mm) in 22 patients with Gemini replacement, whereas the distance was 3.1 mm (-1.5 - 12.3 mm) in the other patients with rotational knee system. The difference was significant. CONCLUSIONS: If the collateral ligaments and cruciate ligaments are removed during the knee replacement operations, the prosthetic joint line is likely to be malpositioned proximally. The fibular styloid and medial or lateral epicondylar reference points can be used to determine proper position of the joint line during operation.

Aged↗

PubMed1993

Choline acetyltransferase immunoreactive neurons innervating labyrinthine and lateral line sense organs in amphibians.

The goal of the present study was to investigate aspects of the central organization of the neurons belonging to the octavolateralis efferent system of amphibians. The perikarya of three genera, Pleurodeles, Xenopus, and Discoglossus, were located in the brainstem by applying retrograde tracers to the appropriate cranial nerves and choline acetyltransferase immunohistochemistry was used to identify cholinergic neurons. The efferent neurons supplying lateral line (Pleurodeles, Xenopus) and labyrinthine (Pleurodeles, Xenopus, and Discoglossus) end organs were found to intermingle in a single octavolateralis efferent nucleus. The neurons lie bilateral to the labelled nerves in Pleurodeles and ipsilateral in Xenopus and Discoglossus. Separate labelling of the anterior and posterior octavus rami provided no evidence for distinct groupings of efferent neurons that could be associated with auditory and vestibular end organs. In all three species many if not all octavolateral efferent neurons displayed immunoreactivity for choline acetyltransferase. They could be distinguished from the cholinergic facial motoneurons, with which they sometimes intermingle, on the basis of either their distinctive size and shape (Pleurodeles, Xenopus) or their location (Discoglossus). Double labelling in Xenopus confirmed the cholinergic nature of the efferent neurons.

Animals↗

PubMed1996

Intra- and interfractional reproducibility of tangential breast fields: a prospective on-line portal imaging study.

PURPOSE: A perception exists that weekly verification films accurately reflect the setup of the tangential breast portals. This prospective study was undertaken to assess patient movement during treatment and setup reproducibility of tangential breast fields using electronic on-line portal imaging. METHODS AND MATERIALS: Thirteen patients with carcinoma of the breast were treated on a linear accelerator equipped with an on-line portal imaging system. Patients were immobilized daily with an alpha cradle. The medial and lateral tangential fields were imaged and 139 fractions, 225 portal fields, and 4450 images were obtained. Images were then analyzed off line and 22,250 measurements were made from these images. Anatomical features recorded include the lung area (LA), central lung distance (CLD), central breast distance (CBD), central flash distance (CFD), and inferior central margin (ICM). Intrafractional variations were calculated for every portal field and fraction for each patient. Interfractional variations were determined by finding the variance of intrafractional means for each patient. A population standard deviation for each of the five parameters for intra- and interfractional variations were determined. The simulation to treatment setup errors were calculated for all five variables. RESULTS: Lung area variation was 1.50 and 4.19 cm(2) [1 standard deviation (SD)] for intra- and interfractional movement. Intrafractional variation for the other four variables ranged from 0.85 mm for ICM to 2.1 mm (1 SD) for CBD, while interfractional variations ranged from 3.2 to 6.25 mm for CBD and ICM, respectively. The simulation-to-treatment setup variation was greater than the interfractional variation for three of the five variables and was similar for the other two. CONCLUSIONS: On-line verification of intrafractional variation shows a moderate deviation from the treatment setup position for all five parameters studied, while interfractional variation showed even greater deviations for these five parameters. To cover the breast target in 95% of cases, margins of 7.70, 7.70, and 10.30 mm corresponding to the CLD, CFD, and ICM distances, respectively, are required.

Breast Neoplasms↗

PubMed2003

The human tissue plasminogen activator-Cre mouse: a new tool for targeting specifically neural crest cells and their derivatives in vivo.

The ontogeny of neural crest cells (NCC) involves a number of orchestrated variety of derivatives, including components of the peripheral nervous system and melanocytes. Thus, it represents an excellent model system to investigate mechanisms controlling epithelial-mesenchymal transitions, cell migration and differentiation, as well as cell proliferation and death. We have established a new transgenic line expressing the Cre recombinase under the control of the human tissue plasminogen activator promoter (Ht-PA). The activity of the reporter in the Ht-PA-Cre/R26R embryos is observed as early as Theiler stage 12 in the cephalic mesenchyme. Later, the targeted cells include all the known derivatives of cranial, vagal, and trunk NCC, including craniofacial structures and cranial ganglia, cardiac and endocrine derivatives, melanocytes, peripheral, and enteric nervous system. At the vagal level, the location of presumptive enteric NCC differs from their avian counterparts in their ability to invade the mesenchyme lateral to the neural tube. In contrast to the Wnt1-Cre line, the Ht-PA-Cre line does not target the central nervous system and therefore renders it more specific for NCC. Our Ht-PA-Cre mice represent a novel model to specifically target conditional mutations in migratory NCC.

Animals↗

PubMed1992

Immunohistochemical and biochemical analysis of N-cadherin expression during CNS development.

The expression of the calcium-dependent adhesion molecule N-cadherin during chick embryo central nervous system (CNS) development was examined by immunohistochemistry and electrophoresis and immunoblotting. During histogenesis, N-cadherin is expressed at high levels in a uniform fashion in many regions of the CNS. However, during later stages of development, expression becomes restricted to the ependymal cells lining the ventricular system and in the choroid plexus. This down-regulation was confirmed by both immunohistochemical and biochemical techniques. The program of expression lags behind in the cerebellum in concert with the delayed development of this region of the brain. A high level of N-cadherin was found to be expressed in the brainstem and spinal cord floorplate, while a low level was detected at the optic nerve head. The results indicate that while, in general, the program of N-cadherin expression is similar in the retina and the brain, certain structures unique to the eye and brain express locally high or low levels of this adhesion protein.

Animals↗

PubMed1981

Electrosensory pathways to the valvula cerebelli in mormyrid fish.

The valvula cerebelli of mormyrid fish has been implicated in the electroreceptive capabilities of these animals. This study uses peroxidase and tritiated amino acid tracing techniques to examine the pathways by which electroreceptive information gains access to the valvula. Ampullary and mormyromast receptor information reaches the medial and ventrolateral portions of the valvula by means of a large, direct projection from n. lateralis, part of the midbrain electrosensory area. In addition, smaller indirect n. lateralis-valvular projections travel via a pretectal nucleus and the so-called postventral thalamic nucleus, Knollenorgan receptor information ends in the dorsolateral portion of the valvula. A small, relatively direct pathway runs via n. medialis ventralis, but most Knollenorgan information appears to travel via an indirect system involving n. extrolateralis pars posterior and n. isthmi. The lateral line processing areas of the valvula project back onto many of the midbrain electrosensory nuclei. These results indicate that much of the cerebellum of this family is devoted to sensory processing rather than motor functions.

Afferent Pathways↗

PubMed2005

What is new in the Wolbachia/Dirofilaria interaction?

Presence of transovarially-transmitted endosymbiontic Wolbachia bacteria in Dirofilaria immitis, and in other filariae of man and animals, presents a new paradigm for our understanding of pathogenesis, treatment and diagnosis of filarial infections. Many of the basic biological characteristics of Wolbachia have yet to be elucidated, but the results obtained to date suggest that canine or the feline hosts can be exposed to D. immitis Wolbachia when larvae, or adult worms, are killed; when Wolbachia are expulsed, with the deposition of microfilariae, from the uterus of the females; and possibly through the excretory system of both male and female worms. The two organs that have the greatest potential of being affected by the Wolbachial metabolic products/antigens released from the adult worms are the lungs and the kidneys. Population of Wolbachia in D. immitis is polymorphic. The life cycle of Wolbachia is complex and may consist of two reproductive modes: multiplication of the bacillary forms by binary fission and by a more complex mode which resembles the Chlamydia-like cycle that consists of three morphological stages: a small, dense body, an intermediate stage with a dense inclusion, and a bacillary form which represents the final product of development and maturation of the small, dense body. The Chlamydia-like cycle offers a potential survival strategy for the Wolbachia by producing more progeny than multiplication by binary fission, and appears to be more active during growth and development of embryos and of the larvae. The small, dense bodies may be the infectious forms responsible for the spread of Wolbachia through the canalicular system, within the lateral chords of filariae. An amorphous membrane that lines the perienteric surface of the body wall may represent a physical barrier that limits the spread and movement of Wolbachia to the perienteric surface of the lateral chords. Wolbachia in D. immitis may also offer therapeutic and diagnostic possibilities. Elimination of Wolbachia by chemotherapy, and the suppressive effect of aposymbiosis on embryonic development of D. immitis, may have potential application for control (sterilization of female worms) and treatment of dirofilariasis. However, the three stages in the life cycle of Wolbachia may be antigenically different and each stage may have a different susceptibility to therapeutic agents. Persistence of dormant small, dense bodies after treatment would allow the Wolbachia to re-establish once the conditions for development would become favorable. Detection of Wolbachial antigens provides an attractive diagnostic possibility to identify D. immitis early in the infection. Further studies on Wolbachia of filariae, including those of D. immitis, will undoubtedly reveal additional information that can be applied towards treatment, diagnosis, and control of filarial infections.

Animals↗

PubMed1994

Electric organ discharge and electrosensory reafference in skates.

Skates possess bilateral electric organs that produce intermittent, weak discharges of relatively long duration compared to the discharges of other weakly electric fish. They, like all elasmobranchs, also have an electrosensory system capable of detecting weak, low-frequency electric fields. Several studies have suggested that the discharge is used in some type of social communication. This study measured the strength and nature of the response of the skate electrosensory system to electric organ discharge. Electric organ discharge (EOD) was elicited via electrical stimulation of the medullary command nucleus in two species of skates. The temporal structure and power spectra of the EODs demonstrated that they should be effective stimuli for the skate electrosensory system. The responses of electrosensory afferent fibers in the anterior lateral line nerve (ALLN) to EODs were variable depending upon the location and orientation of the receptor. The responses of most ALLN fibers were very weak compared to the strong reafference produced by the skate's ventilatory activity. Unlike the common-mode ventilatory reafference, EOD reafference was variable in terms of excitation or inhibition, depending upon receptor orientation. Despite the low signal-to-noise ratio observed in ALLN responses to EODs, it is likely that EODs serve as a communicative signal over moderate distances.

Action Potentials↗

PubMedDate not supplied

Impact of vasculogenesis on solid tumor growth in a rat model.

Peripheral stem cells released from bone marrow (BM) are known to be incorporated into foci of neovascularization and to contribute to solid tumor development. In the present rat Walker256 tumor model, BM suppression induced by total body irradiation resulted in poor growth of the tumor with apparently poor vascularization, and BM transplantation restored tumor growth. Endothelial progenitor cells are considered to be crucial for vasculogenesis, but they are not yet well defined, and methodology for their purification has not been established. As a model to examine the significance of endothelial progenitor cells in tumor-specific vasculogenesis, we utilized an immortalized rat BM-derived endothelial cell line named TR-BME-2. Fluorescence-labeled TR-BME-2 cells injected systemically into rats were accumulated at the tumor site 4 days later. Another rat BM-derived cell line named C2-11, which does not have an endothelial profile, did not show tumor-specific accumulation. The tumor volume in rats treated with TR-BME-2 was significantly larger than that in rats treated with C2-11. Thus, our results suggest the importance of neovascularization by bone marrow-derived endothelial cells for the promotion of tumor growth.

Animals↗

PubMed1977

An on-line method for the acquisition of medical information for computer processing as applied to radiotherapy.

Based on a structured medical record, specially designed for patients with malignant disease, an on-line data capture system has been developed. This enables the collection of virtually any type of information contained in the patient's case notes. The structure of the record is described, with actual examples. The record is typed on a typewriter terminal linked to a mini-computer. Data is recorded as code + heading + value string. The headings are identified automatically, and an internal code generated, describing the type of information. Record keeping according to the principles described was introduced in clinical routine at the department in 1971. Data collection was implemented later that year, using an off-line magnetic tape encoder (IBM MT72). The system has been developed further and converted to a versatile on-line system. The data base, collected with these systems, now contains data on about 20,000 patients.

Computers↗

PubMed1996

A prospective randomized clinical trial comparing two film-screen systems for chest radiography.

OBJECTIVE: To compare conventional and asymmetric film-screen chest radiography systems in a prospective, randomized trial. PATIENTS AND METHODS: Posteroanterior and lateral films were obtained with each system for one healthy volunteer and 49 consenting patients referred from pulmonary clinics and wards (for a total of 27 male and 23 female subjects ranging in age from 16 to 82 [mean 58] years). The radiographs, obtained and presented in random order, were reviewed and rated independently by two experienced radiologists and one resident in radiology; all observers were blinded to patient identification and film type. The Wilcoxon signed rank sum nonparametric test for paired samples was used to test for significant differences between the two film-screen systems. A second evaluation involving direct (blinded) comparison of the two types of films was then performed for each of the 25 patients in whom abnormality was noted during the first evaluation. RESULTS: For the posteroanterior radiographs, the asymmetric film-screen system was significantly better for assessing the trachea and mainstem bronchi, the descending thoracic-aortic edge, the left paraspinal line, the thoracic vertebral body interspace and the azygo-esophageal line (p < 0.05), whereas the conventional system had superior conspicuity in the lateral subpleural zones (p < 0.05). For the lateral radiographs, the asymmetric system was superior for assessing retrosternal lung markings (p < 0.05) but inferior for assessing fissures (p < 0.05). CONCLUSIONS: In general, the asymmetric system was superior for assessing mediastinal features and inferior for assessing the lateral subpleural zones in the posteroanterior radiographs. The asymmetric system was superior for assessing retrosternal lung markings and inferior for assessing fissures in the lateral radiographs. The results for the posteroanterior radiographs were consistent with the results of nonblinded studies reported elsewhere.

Adolescent↗

PubMed2000

Modeling inhibitory plasticity in the electrosensory system of mormyrid electric fish.

Mathematical analyses and computer simulations are used to study the adaptation induced by plasticity at inhibitory synapses in a cerebellum-like structure, the electrosensory lateral line lobe (ELL) of mormyrid electric fish. Single-cell model results are compared with results obtained at the system level in vivo. The model of system level adaptation uses detailed temporal learning rules of plasticity at excitatory and inhibitory synapses onto Purkinje-like neurons. Synaptic plasticity in this system depends on the time difference between pre- and postsynaptic spikes. Adaptation is measured by the ability of the system to cancel a reafferent electrosensory signal by generating a negative image of the predicted signal. The effects of plasticity are tested for the relative temporal correlation between the inhibitory input and the sensory input, the gain of the sensory signal, and the presence of shunting inhibition. The model suggests that the presence of plasticity at inhibitory synapses improves the function of the system if the inhibitory inputs are temporally correlated with a predictable electrosensory signal. The functional improvements include an increased range of adaptability and a higher rate of system level adaptation. However, the presence of shunting inhibition has little effect on the dynamics of the model. The model quantifies the rate of system level adaptation and the accuracy of the negative image. We find that adaptation proceeds at a rate comparable to results obtained from experiments in vivo if the inhibitory input is correlated with electrosensory input. The mathematical analysis and computer simulations support the hypothesis that inhibitory synapses in the molecular layer of the ELL change their efficacy in response to the timing of pre- and postsynaptic spikes. Predictions include the rate of adaptation to sensory stimuli, the range of stimulus amplitudes for which adaptation is possible, the stability of stored negative images, and the timing relations of a temporal learning rule governing the inhibitory synapses. These results may be generalized to other adaptive systems in which plasticity at inhibitory synapses obeys similar learning rules.

Action Potentials↗

PubMed1981

Electroreception in lampreys: evidence that the earliest vertebrates were electroreceptive.

Evoked potential and unit responses from the lamprey brain to weak electric fields demonstrate that lampreys have an electrosensory system as sensitive as those of other electroreceptive fishes. Electrosensory responses were recorded in the dorsal medulla, the midbrain torus semicircularis, and the optic tectum. Similarities in the structure of the anterior lateral line nerves and medullary organization between lampreys and several primitive jawed fishes indicate that the electroreceptive systems are homologous in these taxa. Thus electroreception was probably present in the earliest vertebrates ancestral to both agnathans and gnathostomes.

Animals↗

PubMed2001

Post-operative sensitivity in glass-ionomer versus adhesive resin-lined posterior composites.

PURPOSE: To compare objective and subjective assessments of post-operative sensitivity when class 1 cavities, lined with glass-ionomer or adhesive bonding system, were restored with resin-based composite (RBC). MATERIALS AND METHODS: Occlusal cavities on homologous contra-lateral posterior teeth in 44 male patients attending primary health centers in Riyadh, Saudi Arabia were restored with RBC after a cavity lining of either a light cured glass-ionomer cement (Vitrebond) or an adhesive bonding system (One-Step). RESULTS: Cold response measurements 24 hrs, 7 days and 1 month post-operatively showed that the threshold of pulpal response was significantly lower (P< 0.05) in the restored teeth when the adhesive bonding system served as cavity liner. In addition, based on the patients' subjective assessments, the prevalence of mild or severe post-operative sensitivity was significantly higher (P< 0.05), 24 hrs and 7 days post-operatively, in the teeth with the adhesive bonding system as a cavity liner. After a post-operative period of 1 month, however, there was no significant difference (P> 0.05) between the prevalence of post-operative sensitivity when the restored teeth received a lining of either glass-ionomer or adhesive bonding system.

Acid Etching, Dental↗

PubMed1988

Scientific investigations at a lunar base.

Scientific investigations to be carried out at a lunar base can have significant impact on the location, extent, and complexity of lunar surface facilities. Among the potential research activities to be carried out are: (1) Lunar Science: Studies of the origin and history of the Moon and early solar system, based on lunar field investigations, operation of networks of seismic and other instruments, and collection and analysis of materials; (2) Space Plasma Physics: Studies of the time variation of the charged particles of the solar wind, solar flares and cosmic rays that impact the Moon as it moves in and out of the magnetotail of the Earth; (3) Astronomy: Utilizing the lunar environment and stability of the surface to emplace arrays of astronomical instruments across the electromagnetic spectrum to improve spectral and spatial resolution by several orders of magnitude beyond the Hubble Space Telescope and other space observatories; (4) Fundamental physics and chemistry: Research that takes advantage of the lunar environment, such as high vacuum, low magnetic field, and thermal properties to carry out new investigations in chemistry and physics. This includes material sciences and applications; (5) Life Sciences: Experiments, such as those that require extreme isolation, highly sterile conditions, or very low natural background of organic materials may be possible; and (6) Lunar environmental science: Because many of the experiments proposed for the lunar surface depend on the special environment of the Moon, it will be necessary to understand the mechanisms that are active and which determine the major aspects of that environment, particularly the maintenance of high-vacuum conditions. From a large range of experiments, investigations and facilities that have been suggested, three specific classes of investigations are described in greater detail to show how site selection and base complexity may be affected: (1) Extended geological investigation of a complex region up to 250 kilometers from the base requires long range mobility, with transportable life support systems and laboratory facilities for the analysis of rocks and soil. Selection of an optimum base site would depend heavily on an evaluation of the degree to which science objectives could be met. These objectives could include lunar cratering, volcanism, resource surveys or other investigations; (2) An astronomical observatory initially instrumented with a VLF radio telescope, but later expanding to include other instruments, requires site preparation capability, "line shack" life support systems, instrument maintenance and storage facilities, and sortie mode transportation. A site perpetually shielded from Earth is optimum for the advanced stages of a lunar observatory; (3) an experimental physics laboratory conducting studies requiring high vacuum facilities and heavily instrumented experiments, is not highly dependent on lunar location, but will require much more flexibility in experiment operation and EVA capability, and more sophisticated instrument maintenance and fabrication facilities.

Astronomical Phenomena↗

PubMed2005

Influence of prosodic information on the processing of split particles: ERP evidence from spoken German.

Spoken language comprehension involves the use of different sources of linguistic information such as prosodic, syntactic, lexical, and semantic information. The question, however, of ''when'' and ''how'' these sources of information are exploited by the language processing system still remains unanswered. In the present study, we used event-related brain potentials (ERPs) to investigate the interaction between prosodic, syntactic, and lexical information during the processing of spoken German sentences. The sentence structure was manipulated by positioning a split particle at the end of the sentences after the occurrence of inflected verb whose lexical entry does not contain a split particle (e.g., *Sie alarmierte den Detektiv an [*She alerted at the detective]) [According to linguistic convention, incorrect sentences are marked by an asterisk.]. The prosodic contour of the verb stems was manipulated such that it marked either the presence of a split particle at a later position in the sentence or not. Participants performed an off-line probe-detection task. ERP data indicate that prosodic information of German-inflected verb stems is consulted on-line by the language processing system (''parser'') in order to ''predict'' the presence of a split particle at a later position in the sentence. An N400 effect was observed for the processing of split particles following verb stems which do not take a particle. However, this effect was only observed when the prosody of the verb stem did signal the presence of a split particle. We argue that the N400 component reflects the high costs associated with the lexical search that the language processing system has to perform when confronted with nonexisting words such as these resulting from the combination of the split particle and the verb stem in the present study. Furthermore, as a general reflection of prosodic processes, a Closure Positive Shift (CPS) was found at intonational phrase boundaries. In sum, the present findings provide strong evidence that prosodic information is a good ''predictor'' of upcoming information during the auditory processing of German sentences.

Adult↗

PubMed1988

A lateral line analogue in cephalopods: water waves generate microphonic potentials in the epidermal head lines of Sepia and Lolliguncula.

Many cephalopods have lines of ciliated cells on their head and arms. In the cuttlefish Sepia and the squid Lolliguncula, electrophysiological recordings clearly identify these epidermal lines as an invertebrate analogue to the mechanoreceptive lateral lines of fish and aquatic amphibians and thus as another example of convergent evolution between a sophisticated cephalopod and vertebrate sensory system. Stimulation of the epidermal lines with local water displacements, generated by a vibrating sphere, causes receptor potentials that have many features known from lateral line microphonic potentials. The minimal threshold of the head lines is 0.2 micron peak-to-peak water displacement (calculated at the skin surface) at 75-100 Hz.

Action Potentials↗