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P Wiebe

Publications and source records attributed to P Wiebe.

10 recordsLinked to original sources
PubMed2003

A comparison of bone geometry and cortical density at the mid-femur between prepuberty and young adulthood using magnetic resonance imaging.

In upper extremity bones, a sexual dimorphism exists in the development of periosteal and endocortical bone surfaces during growth. Little is known about developmental patterns of bone geometry at weight-bearing bones like the femur. Using MRI and dual energy X-ray absorptiometry (DXA), this study assessed the differences in mid-femoral total (TA), cortical (CA) and medullary areas (MA), cortical thickness, and cortical density (BMD(compartment)) between prepuberty and young adulthood in 145 healthy subjects (94 females) 6 to 25 years old. Additionally, agreement between mid-femoral total bone volume (TV) measurements by DXA and MRI were investigated. In both sexes, TA, CA, MA, and cortical thickness were significantly larger in adults compared to prepubertal subjects (P < 0.001), and males had greater values than females. This sex difference persisted for TA, CA, and cortical thickness (P < 0.05), but not MA, after adjusting for femur length and weight. Mean (SD) cortical BMD increased from 1.05 (0.07) and 1.09 (0.10) g/cm(3) in prepubertal children to 1.46 (0.14) and 1.42 (0.1) g/cm(3) in young adults, females and males, respectively (P < 0.001). TV measurements by DXA were significantly greater than by MRI (P < 0.001) in young adults. In conclusion, periosteal and endocortical expansion and increasing cortical BMD are the growth processes found at the mid-femur in both sexes. Our findings contrast to that in upper extremity bones, where MA is constant in females during growth. The difference in femoral bone development may be due to higher strains caused by weight bearing and genetic factors. DXA, in contrast to MRI, is inaccurate in the determination of mid-femoral TV measures.

Adolescent↗
PubMed2002

EEG-Pen for medical emergencies.

This paper deals with a handy, mobile emergency EEG device. It provides a direct and immediate access to patients brain activity. This EEG-Pen consists of spring-loaded electrodes and all necessary components. Current mobile EEG systems do not seem to be appropriate for emergencies since they require a lot of time-consuming preliminary work. Usually the skin has to be pre-treated, the electrodes and the wires have to be attached to the body. This prototype of an EEG-Pen would do away with such preliminary measures and therefore becomes an essential tool for emergencies. Good recordings have been obtained. A miniaturized EEG-Pen, which can be easily carried by physicians or medical staff and immediately be used as a "bioelectric signal detector", requires more research.

Electroencephalography↗
PubMed1999

Differential modulation of human immunoglobulin isotype production by the neuropeptides substance P, NKA and NKB.

The modifying effects of tachykinins substance P, neurokinin A and neurokinin B on immunoglobulin production were analyzed in an in vitro culture system. Purified human T- and B-cells were stimulated with TGFbeta2 and IL-5 to induce preferential IgA production. Neuropeptides had the following effects. (1) The levels of IgA and IgG4 production were enhanced by IL-5 and TGFbeta2; IgA levels remained constant or were slightly augmented by neuropeptides, whereas IgG4 was further augmented. (2) IL-5 and TGFbeta2 did not alter IgG3 production, but neuropeptides stimulated secretion of this subclass. (3) IgG1 and IgM production were inhibited by IL-5 and TGFbeta2. This effect was prevented by neuropeptides. (4) Other isotypes including IgG2 and IgE remained unaffected. Except for IgM, these effects were blocked by specific receptor antagonists indicating specificity. The tachykinin receptor NK-1 mRNA was detected in B- and T-cells, whereas NK-3 mRNA was only present in T- and B-cell coculture following activation. Furthermore, neuropeptide effects depended on cytokine co-stimulation and the presence of T-cells. These results suggest that neuropeptides are potent modifiers of preferential IgA synthesis.

B-Lymphocytes↗
PubMed1996

Noninvasive positive-pressure ventilation in acute respiratory distress without prior chronic respiratory failure.

We evaluated the efficacy of noninvasive mechanical ventilation (NIMV) in alleviating distress and avoiding intubation in patients with de novo acute respiratory failure complicating primary medical disorders. Eleven consecutive patients with severe respiratory distress were entered. In all patients a decision to intubate on an urgent basis had been made, but NIMV could be initiated within minutes. The patients suffered from acute pulmonary edema (five), sepsis/ARDS (two), status asthmaticus (two), and severe pneumonia (two). Dyspnea score (max=10) was (+/- SD) 8.4 +.- 1.6, scale for accessory muscle use (max=5) was 4.2 +/- 0.7, and respiratory rate was 37.6 +/- 3.8 min -1. Pa CO2, pH, and base excess (BE) were 48 +/- 18 mm Hg, 7.27 +/- 0.13, and -5.5 +/- 7.4, respectively, with five patients showing severe metabolic acidosis (BE < - 10). NIMV was applied using proportional assist ventilation. There were three early failures. These included the two patients with sepsis/ARDS who did not tolerate the mask. One patient failed because Pa CO2 and pH deteriorated despite subjective improvement. The remaining eight patients demonstrated progressive improvement, and none required intubation. The duration of NIMV was 3 h to 2 d. We conclude that when NIMV is made available on a "few minutes" basis, selected patients with severe de novo respiratory distress/failure caused by reversible medical disorders, who would otherwise have been intubated, can be given substantial relief and be spared intubation.

Acid-Base Imbalance↗
PubMedDate not supplied

[Basis for information transmission with biosignals for development of technical communication aids for handicapped patients].

For the design of communication aids controlled by biosignals for the handicapped, an analysis of the aspects of the significance of information is mandatory. The definition of information in its five aspects statistics, syntax, semantics, pragmatics and apobetics, enables us to conclude that the transmission of information is possible only with voluntarily influenceable biosignal components. The voluntary influencing of the biosignal may be interpreted as a modulation of the amplitude density of the Fourier integral. By calculating the highest possible statistical information content of a biosignal, it is possible to estimate the technical complexity of a biosignal-based communication system. The construction of efficient communication aids is possible when many biosignal components that can be readily and rapidly controlled voluntarily are to be found.

Biosensing Techniques↗