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At least 559 records · Page 31Linked to original sources
PubMed2006

[Growth factors as neuroprotective treatment in Parkinson disease?].

BACKGROUND: One of several probable causation theories of Parkinson disease postulates that brain tissue cannot generate sufficient levels of various growth factors required to sustain the viability of dopamine-producing nerve cells in the presence of as yet unknown toxic factors. The study reported here evaluates the ability of externally applied growth factors to protect the dopamine fibres in the basal ganglia in a toxin-induced animal model of the disease. MATERIALS AND METHODS: All animals (rats) were subjected to selective destruction of the dopamine-producing cells in substantia nigra. The rats were divided into three groups. Two groups received intracerebral treatment with either glia-cell derived neurotrophic factor (GDNF) or a combination of brain-derived neurotrophic factor (BDNF) and GDNF. The third group acted as untreated controls and were given sterile saline. The growth factors were infused directly into the brain by an osmotic pump over a period of 28 days. Brain sections taken from all three groups were evaluated by immunocytochemistry. RESULTS: The two groups of rats that received growth factor infusion displayed a significant improvement in their motor behaviour compared to control animals. Immunocytochemistry studies demonstrated that the group receiving a combination of GDNF and BDNF had an increased number of surviving active fibres in the dopamine system striatum in comparison to the control and GDNF groups. In addition the infusion of growth factors resulted in a proliferation of subventricular cells in the basal ganglia. CONCLUSION: The improved motor function following growth factor treatment in this rat model might be due to a delayed retrograde degeneration of the nigrostriatal nerve fibers. Growth factor infusion also clearly stimulated endogenous stem cells and caused their migration towards the striatum. Our observations indicate that the infusion of growth factors into the brain have a symptomatic and neuroprotective effect in this model.

Animals↗
PubMed1990

Multichannel 18-test panels: are 60% of panels abnormal by chance?

Current teaching concerning the frequency of abnormal results secondary to chance alone in a multichannel panel is theoretically based on the binomial distribution. However, this distribution can be used only when the probability of an abnormal result (pi) is the same for each test in the panel. In modern-day multichannel testing, pi varies from test to test and most often is less than the usually reported 0.05. On the other hand, a test such as cholesterol may have a pi level as high as 0.55. Theoretically the only distribution that can take this variability into consideration is the Lexis distribution, a form of the binomial distribution that allows for varying pi s. Since no formula is available to calculate this distribution, we wrote a computer program to generate it. We arranged 18-test panels from 203 normal patients in a frequency distribution. This was then compared with the theoretical Lexis and binomial distributions. This analysis showed that although there was a 50% chance of having one abnormality per panel and a 16% chance of having two abnormalities per panel, there was less than 4% chance of having three or more abnormalities per 18-test panel. In addition, most of the abnormalities noted were minor and were thought to be clinically unimportant.

Adult↗
PubMed1990

Relative decompression risk of dry and wet chamber air dives.

The difference in risk of decompression sickness (DCS) between dry chamber subjects and wet, working divers is unknown and a direct test of the difference would be large and expensive. We used probabilistic models and maximum likelihood estimation to examine 797 dry (and generally resting and comfortable) and 244 wet (and generally working and cold) chamber dives from the Defence and Civil Institute of Environmental Medicine, supplemented with 483 wet (working, cold) dives from the Navy Experimental Diving Unit. Several analyses considered whether dry and wet data were distinguishable using several models, whether models obtained from one set of exposure conditions would correctly predict the occurrence of DCS in the other condition, and whether a single wet-dry risk difference parameter was different from zero. Although the two conditions may not produce identical risks, immersion appears to change relative risk of DCS by less than 30% and certainly involves less than a doubling of DCS risk. Uncontrolled differences in exercise and temperature stresses unavoidably complicate interpretation. Several methods are presented to extrapolate results from dry-test subjects in decompression trials to expected at-sea performance.

Data Interpretation, Statistical↗
PubMed1989

[Use of the Monte Carlo method for predicting the outcome of hypertension].

A group of 764 out-patients (359 men and 405 women) was studied 10-24 years after having received clinical treatment for hypertension. After discharge from the clinic 455 patients died. The degree of the disease development was defined in 164 out of 178 survivals. The fate of 131 subjects was unknown. By using the theory of probability and Monte Carlo method we calculated mean times of progress from one class to another (according to Tochowicz's classification) and mean survival times at particular stages of the disease. Hypertension progress from class II to class III was 11.4 years, and survival time measured from the diagnosis to the manifestation of class II was 12.3 years. Progress from class III to class IV was 8.0 years, and survival time of patients with class III was 7.3 years. In class IV patients mean survival time was only 2.5 years. In patients died of hypertension complications mean survival time was 17.1 years. A single control study by using the Monte Carlo method permits a definition of the dynamics in the development of hypertension and duration of its successive stages.

Female↗
PubMedDate not supplied

Diagnosis by the bit: a method for evaluating the diagnostic process.

The extent to which a diagnostic observation or test contributes to a diagnosis is usually represented by a conditional, or Bayesian, probability. According to information theory, the contribution of a diagnostic observation can also be measured in bits of information. This offers a representation of the Bayes rule which may be useful in comparing and evaluating diagnostic sequences, since the diagnostic contributions of the various tests, expressed as bits of information, are additive, providing a simple and graphic representation of the diagnostic process.

Bayes Theorem↗
PubMed1989

[Stereometric characteristics of the ultrastructure of presynaptic terminals in the dorsal horn of the cat spinal cord].

Ultrastructure of 240 axo-dendritic presynaptic terminals (PT) in the dorsal horn of the spinal cord of cat was investigated using the morphometrical statistic method. Parameters describing shape and average spatial radius of the three-dimensional PT (approximated by irregular ellipsoid) were estimated on the basis of the morphometry of random PT sections using ideas of the theory of probabilities. A lack of correlation between the synaptic operative zone localization and features of the terminals' shape was demonstrated. The distribution of the spatial PT radii was obtained. The obtained distribution elicited the relatively small variability of these parameters.

Animals↗
PubMedDate not supplied

Estimating the combined effect of several disease precursors in health risk appraisal.

Health risk appraisal is an attractive health education technique but suffers from methodologic weaknesses. Many of the problems center on the formula that is usually used to estimate the combined effects of different disease precursors. The formula does not reflect current models of disease causation, underestimates the effects of protective factors, and confounds the effects of different precursors. We suggest a modification that resolves these problems by estimating the prevalence and associated composite relative risk for each combination of precursors before calculating the numerical estimate of combined risk. This method can be applied to the many diseases for which the data needed to support a multivariate approach are not available. We recommend its incorporation into existing appraisal instruments.

Attitude to Health↗
PubMed1986

[The history of tracheotomy. I].

Tracheotomy is one of the oldest operations. Indications for and methods of the operative technique are reported already from the ancient times. The following outline - subdivided in three parts - tries to give a comprehensive survey of the development of tracheotomy throughout the centuries. The first part is concerned with the role of tracheotomy in antiquity, in Greek and Roman medicine and in the medicine of the Arabians at the turn of the millennium according to our time. The first tracheotomy is said to have been performed by Asklepiades of Bythinien, who lived in Rome during the last century before the Christian era. The question whether tracheotomy would be of use or not was highly controversal in the following centuries. There were advocates of the operation (for example Antyllus, Paulus von Aegina), but there were strict antagonists, too (for example Aretaeus). In Arabian medicine finally, tracheotomy had an important rank in theory, but probably it had never been performed in humans. The second part of this paper is occupied with the establishment of tracheotomy in the medicine of the European middle ages. Despite many ethical reservations, it became generally accepted as the last live-saving method in certain syndromes. Protagonists of the method included Ambroise Paré, Thomas Fienus, Hieronymus Fabricius ab Aquapendente, Julius Casserius, and Johannes Scultetus. A new method of performing tracheotomy, the opening of the trachea with the use of a trocar, was first described by Sanctorius Sanctorius (1561-1636). The third part of this outline describes the development of the method of tracheotomy in the last 400 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Ethics, Medical↗
PubMed1986

[A new method for determining an infectivity index in assessing the intensity of an epizootic process].

A new method was suggested to determine the index of deadliness in fixing the intensity of the epizootic process as manifested in its two forms--apparent and inapparent. The method is based on the calculus of probability--a most general formula for the sum of any kind of events. The results obtained have been compared with those reached with the already existing two other methods. The model employed consist of theoretically composed examples corresponding to similar ones in the practice as well as of investigations on Salmonella abortions in sheep. The new method can be employed with all kinds of initial data and results in various variants.

Abortion, Veterinary↗