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Biomedical subjects

B Kegel

Publications and source records attributed to B Kegel.

At least 19 recordsLinked to original sources
PubMed2006

Effect of propofol on seizure-like phenomena and electroencephalographic activity in children with epilepsy vs children with learning difficulties.

There is an ongoing debate as to whether propofol exhibits pro- or anticonvulsant effects, and whether it should be used in patients with epilepsy. We prospectively assessed the occurrence of seizure-like phenomena and the effects of intravenous propofol on the electroencephalogram (EEG) in 25 children with epilepsy (mean (SD) age: 101 (49) months) and 25 children with learning difficulties (mean (SD) age: 52 (40) months) undergoing elective sedation for MRI studies of the brain. No child demonstrated seizure-like phenomena of epileptic origin during and after propofol sedation. Immediately after stopping propofol, characteristic EEG changes in the epilepsy group consisted of increased beta wave activity (23/25 children), and suppression of pre-existing theta rhythms (11/16 children). In addition, 16 of 18 children with epilepsy and documented EEG seizure activity demonstrated suppression of spike-wave patterns after propofol sedation. In all 25 children with learning difficulties an increase in beta wave activity was seen. Suppression of theta rhythms occurred in 11 of 12 children at the end of the MRI study. In no child of either group was a primary occurrence or an increase in spike-wave patterns seen following propofol administration. The occurrence of beta wave activity (children with learning difficulties and epilepsy group) and suppression of spike-wave patterns (epilepsy group) were transient, and disappeared after 4 h. This study demonstrates characteristic, time-dependent EEG patterns induced by propofol in children with epilepsy and learning difficulties. Our data support the concept of propofol being a sedative-hypnotic agent with anticonvulsant properties as shown by depression of spike-wave patterns in children with epilepsy and by the absence of seizure-like phenomena of epileptic origin.

Adolescent↗
PubMed2002

In vitro determination of specific toxicity in tetanus vaccines.

Tetanus vaccine is prepared from detoxified tetanus neurotoxin. To ensure the absence of residual toxin activity or to exclude the reversion to toxicity reliable control testing is based on in vivo methods, because no in vitro assay provides the required specificity and sensitivity. Tetanus neurotoxin is a 150 kDa protein produced by Clostridium tetani. The 50 kDa light chain of this neurotoxin belongs to the family of zinc metalloproteases. It cleaves synaptobrevin, a small synaptic vesicle protein, which is involved in neuroexocytosis, at the single Q76-F77 peptide bond. To develop a sensitive in vitro assay capable of quantifying the proteolytic activity of this toxin, we used as substrate a recombinant fragment of synaptobrevin2 (1-97). For detecting the cleavage products a peptide antibody raised against the N-terminal cleavage site was used. In Western Blot analysis only the cleaved substrate was detected while the uncleaved substrate showed no signal. In different approaches, recombinant synaptobrevin was either (i) bound to a microtitre plate, reduced toxin was added and the N-terminal cleavage product was detected by a specific antibody or (ii) the cleavage was performed in test tubes, the samples were transferred to a microtitre plate and immobilised cleavage products were detected. When toxoid or crude toxin is used, non-specific cleavage of synaptobrevin substrate occurs. Depending on the toxoid used different patterns of degradation of substrate are visible in Western Blots. Different protease inhibitors and reaction conditions seem to have an effect on the inhibition of this non-specific cleavage.

Amino Acid Sequence↗
PubMed2001

Multiple ecto-nucleotidases in PC12 cells: identification and cellular distribution after heterologous expression.

The physiological action of extracellular ATP and other nucleotides in the nervous system is controlled by surface-located enzymes (ecto-nucleotidases) of which several families with partially overlapping substrate specificities exist. In order to identify ecto-nucleotidases potentially associated with neural cells, we chose PC12 cells for analysis. PC12 cells revealed surface-located ATPase and ADPase activity with apparent K(m)-values of 283 microM and 243 microM, respectively. Using PCR we identified the mRNA of all members of the ecto-nucleoside triphosphate diphosphohydrolase family investigated (NTPDase1 to NTPDase3, NTPDase5/6), of ecto-nucleotide pyrophosphatase/phosphodiesterase3 (NPP3), tissue-non-specific alkaline phosphatase and ecto-5'-nucleotidase. The surface-located catalytic activity differed greatly between the various enzyme species. Our data suggest that hydrolysis of ATP and ADP is mainly due to members of the ecto-nucleoside triphosphate diphosphohydrolase family. Activity of ecto-5'-nucleotidase and alkaline phosphatase was very low and activity of NPP3 was absent. For a detailed analysis of the cellular distribution of ecto-nucleotidases single and double transfections of PC12 cells were performed, followed by fluorescence analysis. Ecto-nucleotidases were distributed over the entire cell surface and accumulated intracellularly in varicosities and neurite tips. PC12 cell ecto-nucleotidases are likely to play an important role in terminating autocrine functions of released nucleotides and in producing extracellular nucleosides supporting the survival and neuritic differentiation of PC12 cells.

Adenosine Diphosphate↗
PubMed1997

An ecto-ATPase and an ecto-ATP diphosphohydrolase are expressed in rat brain.

Extracellular nucleotides acting as signaling molecules are inactivated by hydrolysis catalyzed by ecto-nucleotidases. ATP is sequentially degraded via ADP and AMP to adenosine. Enzymes that can be involved in the extracellular hydrolysis chain are ecto-ATP diphosphohydrolase (ecto-apyrase), ecto-ATPase, ecto-ADPase and 5'-nucleotidase. Mammalian ecto-ATP diphosphohydrolase is a member of a family of apyrases sharing four "apyrase conserved regions" that presumably participate in the formation of the catalytic site. We report the presence of ecto-ATP diphosphohydrolase in rat brain and the primary structure of a new mammalian member of the apyrase family. Expression in CHO cells shows that it represents an ecto-ATPase. As revealed by Northern analysis of rat tissues, the ecto-ATPase is co-expressed with ecto-ATP diphosphohydrolase in heart, kidney, spleen, thymus, lung, skeletal muscle and brain. Signals for both ecto-nucleotidases are very weak in liver. mRNAs for both proteins are present in PC12 cells, suggesting that the two nucleotidases may be co-expressed in the same neural cell. Using computer-aided sequence analysis, primary structure and membrane topography are compared with those of other members of the apyrase family.

Adenosine Triphosphatases↗
PubMed1981

Effects of isometric muscle training on residual limb volume, strength, and gait of below-knee amputees.

This study was undertaken to determine if prosthetic suspension capabilities of below-knee amputees could be improved by using biofeedback in a controlled exercise program. Improvements in muscle bulk of four amputees were assessed. Changes in transverse cross-sectional areas and suspension ability of the residual limb were measured. The effect of muscle training on gait and on muscle-use patterns during gait was observed. Marked increases in muscle bulk below the knee and improvement in suspension capabilities were seen in two of the subjects, and somewhat lesser improvements were seen in the remaining two subjects. From these changes, one could modify prosthetic designs to take advantage of the residual limb muscles for suspension. For this reason, training the below-knee amputee to exercise the residual limb musculature should become part of routine physical therapy management. In this study, biofeedback was proven to be a useful tool for the reeducation of the residual limb musculature.

Amputation, Surgical↗
PubMed1980

Recreational activities of lower extremity amputees: a survey.

This study summarizes a detailed questionnaire evaluation of recreational activities participated in by 100 persons with lower extremity amputations. Additional information was obtained from prosthetists and physical therapists. Approximately 60% of the respondents are active in sports. Younger persons of either sex, who have had amputations for congenital deformities or trauma, are most active. Level of amputation does not appear to be a determining factor as to whether amputees participated or not. The most common recreational activities are fishing and swimming. Sports causing the amputee most discomfort are hunting and jogging. The ability to run and jump is the most difficult to achieve. Reasons for non-participation are pain, embarrassment, insufficient training and lack of organized sports programs for the disabled. Fear of further injury or an overprotective family are not inhibiting factors, nor is cost of the prosthesis. Only a few people wear specifically designed recreational prostheses, and only one-third of the amputees believe that their prosthetist is knowledgeable about recreational prostheses, while 40% feel the prosthetist discouraged their own ideas about prosthetic innovations. Therapists also proved inadequate in their knowledge and efforts at preparing the amputee for recreation. The amputees indicate a need for improved prosthetic design, and believe that insufficient information, both verbal and written, was given to them.

Adult↗
PubMed1978

Functional capabilities of lower extremity amputees.

One hundred thirty-four lower extremity amputees were evaluated from six months to 12 years postamputation by means of retrospective questionnaires. Patient population was similar to that of the "Amputee Census" in terms of sex, amputation level and cause of amputation. Information was gathered on activities generally considered essential for daily living, vocation and recreation, living arrangements and adjustments therein, as well as feedback on the patients' beliefs concerning what rehabilitation personnel should be doing to improve amputees' lifestyle. The relationship of functional outcome to age, amputation level, and cause of amputation was also evaluated. Results showed that most amputees did not resume a completely normal lifestyle and many modifications were made. The most popular recreational activities were fishing and swimming. Activities that amputees found most difficult were running and walking long distances. Patients requested better communication between professional staff and themselves. Below-knee amputees were significantly more independent than above-knee and bilateral amputees, but the differences between above-knee and bilateral amputees were statistically insignificant. Tumor patients did better than the other three etiologic groups. As age increased, functional independence decreased.

Activities of Daily Living↗
PubMed1977

Load cell: a device to monitor weight bearing for lower extremity amputees.

The PRS-Moore Load Cell for use in immediate postoperative prosthetic fitting for above- and below-knee amputees is described. The design incorporates an audible warning device which will sound whenever the wearer applies more than the predetermined weight on the affected limb. The device is easy to use in a clinical setting and can be incorporated into any endoskeletal pylon. The cost per unit is approximately $125, and the cell can be reused for successive patients.

Amputees↗
PubMed1976

Controlled environment treatment (CET) for patients with below-knee amputations.

This paper describes a new approach to early postsurgical wound management of the patient with a below-knee amputation. The method involves using the Controlled Environment Treatment (CET) machine, which wasdeveloped in England. A brief explanation of the components of the machine and its capabilities are listed. Ambient pressure, temperature, sterility, and humidity are easily controllable; advantages and disadvantages of this device over immediate post-operative plaster and conventional dressings as they relate both to wound environment and to physical therapy are mentioned. The early postsurgical therapy program used at Prosthetics Research Study is outlined.

Air Pressure↗