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G Lehnert

Publications and source records attributed to G Lehnert.

At least 37 records · Page 2Linked to original sources
PubMed1998

[The path to "Doctor of Medicine"--how do doctoral candidates evaluate their dissertation?].

BACKGROUND AND OBJECTIVE: The value of medical dissertations has for some time been controversial. Critical opinions have, on the one hand, been directed against the effort required, its duration and the concept behind these dissertations, while asserting, on the other hand, that such dissertations hinder studying and lead to unnecessary lengthening of the medical curriculum. PARTICIPANTS AND METHOD: In collaboration with the Medical School in Hanover a questionnaire was sent to all the 189 dissertationists of one year, to be returned anonymously. It contained 16 questions about the dissertation itself, supervision. time spent on it, total duration of medical course and effect of the dissertation on the individual's medical studies. The answers were evaluated statistically by explorative data analysis. RESULTS: 181 questionnaires could be evaluated (96%). Average age of those questioned was 30.5 years, median duration of medical studies to-data was 13 semesters. For 80% it was the first attempted dissertation. 22% had been working on an entirely experimental topic (laboratory or animal experiments). The median time from starting to submitting the dissertation was 4 years, the median time of the experimental phase one year. Two-thirds of students said that work on the dissertation had not prolonged their studies. Supervision during various phases of the dissertation was overwhelmingly judged to have been "very good" or "good". Altogether 90% of dissertationists thought that it had been personally meaningful, and they would recommend it to younger costudents. CONCLUSIONS: The results of this study show that a universal criticism of medical dissertations does not stand up to detailed enquiry. Successful dissertationists highly rated their value both to themselves and to scientific medicine. The medical dissertation should therefore firmly remain as part of medical studies and of research within them.

Academic Dissertations as Topic↗
PubMed1998

Heterogeneity of Borrelia burgdorferi sensu lato demonstrated by an ospA-type-specific PCR in synovial fluid from patients with Lyme arthritis.

Borrelia burgdorferi sensu lato, the etiological agent of Lyme borreliosis, has been divided into three genospecies: B. burgdorferi sensu stricto (OspA-type 1), B. afzelii (OspA-type 2) and B. garinii (OspA-type 3-7). Whereas in Europe B. afzelii (OspA-type 2) is predominant among human skin isolates and B. garinii (OspA-type 3-7) among human CSF isolates, some previous serological studies suggested that Lyme arthritis is also associated with B. burgdorferi sensu stricto in Europe. In the present study we designed ospA type-specific PCRs and identified four different ospA types associated with Lyme arthritis. Our study group consisted of 20 patients with positive serology (ELISA and immunoblotting) and clinical criteria for Lyme arthritis. B. burgdorferi DNA was detected in 13 patients and in none of 10 control patients from synovial fluid. We identified ospA-type 1 (26.6%), ospA-type 2 (33.3%), ospA-type 4 (6.6%) and ospA-type 5 (33.3%). Our conclusion is that in Europe B. burgdorferi sensu lato strains causing Lyme arthritis are considerably heterogeneous and that there is no prevalence of certain genospecies or OspA-types among this strains.

Adolescent↗
PubMed1998

Diagnostic value of proteins of three Borrelia species (Borrelia burgdorferi sensu lato) and implications for development and use of recombinant antigens for serodiagnosis of Lyme borreliosis in Europe.

More and more assays for the serodiagnosis of Lyme borreliosis (LB) are based on recombinant antigens. However, so far, there is no consensus as to which are the most specific and sensitive proteins and how they should be used in combination to obtain tests with the best discrimination abilities. The present study was preceded by a detailed analysis of Western blots (WB) using whole-cell lysates of Borrelia burgdorferi sensu stricto strain PKa2, B. afzelii PKo, and B. garinii PBi (U. Hauser, G. Lehnert, R. Lobentanzer, and B. Wilske, J. Clin. Microbiol. 35:1433-1444, 1997). For the present work, the data bank from that study, containing information about the reactivities of 330 sera (from patients at different stages of LB [n = 189]; control group, n = 141), was reused. The specificities and sensitivities of various combinations of proteins from different strains were calculated for different interpretation criteria. For immunoglobulin G (IgG) WB, the recommended combination of antigens available to date as recombinant proteins included p83/100 of PKa2, p83/100 of PKo, p39 of PKo, p39 of PBi, and OspC of PBi (interpretation criterion, at least one reactive band required for a positive WB; specificity, 96.5%; sensitivity, 56.1%). The further addition of p58 of PKo, p17 of PKo, or p14 of PKo was most favorable in terms of both a considerable gain of sensitivity and little loss of specificity. IgG Western blotting with a whole-cell lysate of strain PKo might be improved by the addition of OspC of PBi. For IgG WB, the best combination, out of all bands, was p83/100, p58, p39, p30, and p21 of all three strains and OspC of PBi, p17b of PBi, p56 of PKa2, p43 of PKo, p17 of PKo, and p14 of PKo (interpretation criterion, at least two reactive bands required for a positive WB; specificity, 97.2%; sensitivity, 61.4%). An interpretation criterion of at least two reactive bands is more reliable than one of only one reactive band. For IgM WB, the best combination was OspC of PKo, OspC of PBi, p39 of all three strains, p17 of PKo, and strong reactions with p41 of all three strains (interpretation criterion, at least one reactive band required; specificity, 97.9%; sensitivity, 47.0%).

Antibodies, Bacterial↗
PubMed1998

Evaluation of an auto-CPAP device for treatment of obstructive sleep apnoea.

BACKGROUND: Auto-CPAP machines used in the treatment of obstructive sleep apnoea (OSA) are designed to vary the treatment pressure automatically in order always to apply the actually needed pressure. Consequently they should be able to achieve at least identical therapeutic effects as conventional constant pressure CPAP with a lower mean treatment pressure. The present study was designed to evaluate the therapeutic efficacy and the treatment pressure of an auto-CPAP machine (REM + auto, SEFAM) in comparison with a conventional CPAP device. METHODS: Following CPAP titration, 16 patients with OSA were allocated to receive conventional CPAP and auto-CPAP treatment under polysomnographic control in a randomised order. After each treatment the patients were asked to assess the therapy using a questionnaire; a vigilance test was also carried out and subjective daytime sleepiness was evaluated using the Epworth Sleepiness Scale (ESS). RESULTS: The mean (SD) apnoea/hypopnoea index (AHI) during auto-CPAP treatment was comparable with that during conventional CPAP treatment (4.2 (5.1) versus 3.6 (4.0)). Neither an analysis of sleep architecture nor the arousal index (7.4 (4.1) versus 7.0 (4.3)) revealed any significant differences. Daytime sleepiness measured with the ESS was also comparable (5.3 (3.4) versus 6.5 (4.2)). The vigilance test showed normal values after both treatments in all patients with no significant differences. The mean pressure during auto-CPAP treatment (8.1 (2.9) mbar), however, was significantly higher than that employed in conventional CPAP treatment (7.6 (2.7) mbar; mean difference 0.5 mbar; 95% CI 0.1 to 0.9 mbar; p < 0.05). CONCLUSIONS: Auto-CPAP was equally as effective as conventional CPAP with respect to therapeutic efficacy. The aim of reducing the treatment pressure with auto-CPAP, however, was not achieved.

Adult↗
PubMed1998

[Significance of social medicine in the medical contract office].

In the German statutory social security system, the necessity of long-term care for chronically ill persons with multi-morbidity and reduced performance has made the socio-medical management of illness and its consequences an important characteristic of primary medical activity. In routine practice a discrepancy between the practical demands and social-medical insights has often been observed. With this in mind, the aim of our pilot study was to systematically collect data on the state of the art and attitudes towards the relevant spheres of work in a defined group of physicians and analyse this data. The study was carried out in the form of a voluntary questionnaire within the medical association (Arztlicher Kreisverband-AKV) in the area of Erlangen-Hochstadt. The database was a computer-processible, anonymous questionnaire with which first of all general socio-demographic and activity-related data was collected. The following 10 questions included, in addition to an estimation of the participants' own socio-medical knowledge, questions on the general status of socio-medical knowledge and how the individual gained this knowledge and the importance of socio-medical themes in routine practice. The data was evaluated using descriptive statistics in the form of exploratory data analysis. Of the 320 physicians registered at the time of the investigation (4/96), 89 (31 female doctors, 58 male doctors) sent back a questionnaire that proved useful (returns: approx. 28%). Significant sex-related or specialisation-related differences with regard to participation in the study were not observed. The ratio of female to male doctors and of general practitioners to specialists in the study collective corresponded more or less to the distribution in the total group. The participants had a median age of 41 years (minimum 31, maximum 71) and had been in practice for a median of 11 years (maximum 43 years, minimum 1 year). 36% were general practitioners, 64% specialists. 97% regarded sound knowledge in socio-medicine as essential for doctors wishing to set up practice. 70% regarded their own knowledge of socio-medicine as being in need of improvement. 85% regarded their knowledge as having been insufficient at the start of their medical careers. With regard to doctors gaining socio-medical competence, routine practice and their own autodidactic capabilities played an important role. 84% would like to see increased teaching of socio-medical themes during specialist training courses. For over 70% socio-medicine is a part of medical studies as a subject in its own right. The content and aims of New Public Health were known to 45%. Among the areas of socio-medical work the care of chronically ill persons was given highest priority. Preventive measures were also accorded high relevance by the participants, and they were particularly interested in preventive medicine. Taking into consideration conceptional problems (e.g. the size of the random sample/selection effects) it was found that: despite many years of practice in some cases, doctors feel there is a deficit in their socio-medical knowledge--prcctical knowledge is mainly gained autodidactically during routine practice ("learning by doing"). There is a clear wish for increased consideration of socio-medical themes in specialist training courses. The great importance of socio-medical tasks as part of medical practice is undeniable to the study collective. The results underline the necessity for improved communication and co-operation between doctors involved in primary medical activity and in socio-medicine.

Adult↗
PubMed1998

Occupational health in Germany and other countries of the European Union.

Occupational medicine is affected to a much greater extent by national legal and social conditions than by clinical issues. The different preconditions specific to each country serve to restrict the scientific dialogue on issues of occupational medicine. Therefore, in this paper are described the organisation and the under- and postgraduate education of occupational medicine in Germany and other European countries (Austria, Belgium, Denmark, Italy, United Kingdom). In summary one can state that in many member states of the EU there is a lack of undergraduate training in occupational medicine for students and there are distinct systems for the postgraduate training and assessment of occupational physicians. The practice of occupational medicine in the EU countries probably has many similarities. The responsibilities of occupational physicians are rather comparable, though in some countries the approaches of occupational medical prevention and the interest in evaluating the structure, process and outcome of many of the activities of occupational medicine seem to recede something into the background.

Education, Medical, Undergraduate↗
PubMed1997

[Auto-CPAP treatment in obstructive sleep apnea syndrome: a prospective randomized study during initiation of treatment].

OBJECTIVE: The efficacy and acceptance of self-regulated continuous positive airway pressure (auto-CPAP) ventilation was compared with conventional CPAP administration in the treatment of patients with obstructive sleep apnoea. PATIENTS AND METHODS: Using a cross-over design, under polysomnographic monitoring in a sleep laboratory, 25 patients with obstructive sleep apnoea underwent conventional CPAP or auto-CPAP treatment. Using a questionnaire, patients gave their assessment of its acceptability and efficacy after each treatment session. RESULTS: The mean pressure during treatment was the same in the two groups (7.2 +/- 1.9 versus 7.1 +/- 1.9 mbar; no significant difference). Maximal pressure during auto-CPAP averaged 3.7 +/- 2.1 mbar higher than during conventional CPAP ventilation. The mean apnoea-hypopnoea index (AHI) during auto-CPAP, 4.4 +/- 4.3 mbar, during auto-CPAP was significantly higher than during conventional CPAP treatment (2.8 +/- 2.8 mbar; P = 0.044). In eight patients on auto-CPAP an AHI of 5 or less could not be reached, while an AHI of 5 or less was obtained in all but three patients under conventional CPAP. In a subgroup of 17 patients, in whom a reduction of AHI to at most 5 was achieved with both conventional and auto-CPAP, analysis of sleep pattern and of arousals was similar with the two forms of ventilation. Several patients reported that with auto-CPAP falling in sleep was more difficult and they slept less well. None of the patients preferred auto-CPAP. CONCLUSION: By means of the auto-CPAP neither a pressure reduction nor an improvement in compliance could be achieved. Therapeutic effectiveness was significantly less as with conventional CPAP therapy.

Adult↗
PubMed1997

[Cardiovascular diseases caused by unemployment? An analysis from the viewpoint of social medicine].

Unemployment has become a sociopolitical problem of great importance in the Western industrialised countries. Although negative effects on social life and psyche resulting from unemployment are regarded as scientifically accepted today, a possible causal relationship between job loss and somatic illnesses is still a matter of controversy. A possible target organ is the cardiovascular system. The aim of this study was, therefore, to check by means of extensive literature analysis to what extent unemployment can be seen to influence cardiovascular morbidity. Particular attention was paid to the method used and the clinical relevance of the results. Person-related epidemiological studies published since 1980 which investigated changes in cardiovascular risk factors associated with unemployment or prevalence rates of manifest disease influenced by unemployment, were included in the final evaluation. In some cases statistically significant associations were found between unemployment and the increase in cholesterol levels or systolic/diastolic blood pressure, but the clinical relevance of such slight changes is questionable. To consider unemployment as an independent, social, cardiovascular risk factor is at present unwarranted. An increase in the prevalence rates of coronary heart disease or arterial hypertonia causally linked in some studies with unemployment is scientifically questionable due to severe methodological shortcomings. On the basis of the currently available methodologically acceptable studies, the question of a qualitative contribution of unemployment to cardiovascular disease cannot be answered conclusively.

Adult↗
PubMed1997

Neurotoxicity of long-term low-level exposure to carbon disulphide: results of questionnaire, clinical neurological examination and neuropsychological testing.

OBJECTIVE: Carbon disulphide (CS2) is highly neurotoxic. There is ample evidence of damage to the peripheral and central nervous system. The air concentration at which such adverse effects can first be observed is presently a subject of controversy. METHODS: In a cross-sectional study of CS2-exposed workers from the viscose industry and healthy controls, data on neurological complaints, basic laboratory diagnosis, clinical neurological examination and neuropsychological testing were evaluated. Data were from 222 workers in the viscose industry exposed to CS2 and 191 employees from the same factory with similar physical and psychological stress factors but without occupational contact with neurotoxic substances. Multiple linear or multiple logistic regression analysis was used to check for statistical differences. RESULTS: The median of the CS2-measurements using personal air sampling was below the current maximum concentration permissible (MAK value) in Germany (10 ppm) in all departments. The threshold limit value was, however, exceeded in almost 10% of the persons investigated. Exposure fluctuated between < 0.2 and 65.7 ppm (median of all departments was 4.02 ppm). As a parameter of internal exposure, CS2-metabolite 2-thio-1,3-thiazolidine-4-carboxylic acid (TTCA) concentrations in the urine of the exposed persons were between < 0.16 and 10.9 mg/g creatinine (median 1.43 mg/g). CONCLUSIONS: Neither an increase in subjective complaints nor an increase in pathological findings in clinical-neurological and neuropsychological examination could be found in persons exposed to CS2 at the exposure levels described.

Adult↗
PubMed1997

Internal exposure to hazardous substances of persons from various continents: investigations on exposure to different organochlorine compounds.

UNLABELLED: The aim of the study was to investigate the concentration of organochlorine compounds of environmental-medical relevance in biological materials from refugees with regard to their countries of origin and to compare these concentrations with the internal exposure of the German general population. METHODS: During medical examination after entry to Germany specimens could be taken from the refugees to determine the following parameters of biological monitoring: 1,1-dichloro-2,2-bis(-chlorophenyl)-ethylene (DDE-P), polychlorinated biphenyls (PCB-P), pentachlorophenol (PCP-P) and the beta- and gamma-hexachlorocyclohexanes (beta-HCH-P, gamma-HCH-P) in plasma and the excretion of chlorophenols (4-MCP-U, 2,4-DCP-U, 2,5-DCP-U, 2,4,5-TCP-U, 2,4,6-TCP-U, 2,3,4,5-TeCP-U, 2,3,5,6-TeCP-U) in urine. One hundred and three men (13 from former Yugoslavia, 29 from the former USSR, 33 Africans and 28 Asians) ranging from 16 to 53 years of age (median 27 years) were investigated. Thirty four male Germans without occupational exposure to these substances and a similar age structure (age 25-36 years; median 26 years) served as a control group. RESULTS: A much higher level of internal exposure was found for the DDT metabolite, DDE, for those persons from Asia, the former USSR and Africa compared with the German controls (medians: 16.9 micrograms/l, 11.9 micrograms/l and 10.9 micrograms/l) and 1.1 micrograms/l). The levels of PCB in plasma were below the detection limit in the majority of refugees. In the control group, however, the PCB levels were higher (sigma PCB; median: 2.1 micrograms/l, maximum: 13.3 micrograms/l). The highest beta-HCH concentrations, up to a maximum of 15.5 micrograms/l, were detected in the persons from the former USSR and Asia. The five groups do not differ with regard to internal exposure to PCP and gamma-HCH. Renal excretion of 4-MCP, 2,4-DCP and TeCP did not differ between the five groups. The concentrations of 2,5-DCP in urine, however, were significantly lower in the Germans than the refugees from the four regions investigated. The median for the Germans was 3.0 micrograms/l and for the refugees between 10.8 and 14.7 micrograms/l. Also the levels of 2,4,5-TCP and 2,4,6-TCP in urine were lower in the German controls than in the men from the former USSR, Africa and Asia. CONCLUSIONS: Organochlorine compounds exist worldwide due to their extensive use. There are, however, regional differences for the various substance groups, which during biological monitoring are seen in the different background exposures of the general population. Particularly characteristic are markedly higher levels of DDE in plasma from the refugees compared with the German population.

Adolescent↗
PubMed1997

Computer-assisted classification system for chest X-ray and computed tomography findings in occupational lung disease.

The ILO classification of pneumoconiotic changes in the lungs and pleura has become a standardized and widely accepted method of documentation in occupational medicine. Recently a classification system for computed tomography/high-resolution computed tomography (CT/HRCT) findings in the lung has been proposed as well. For both classification systems, computed-assisted programs have been developed that allow the storage and archiving of the results as well as further statistical processing. The programs are compatible with usual hardware configurations, have a comprehensible and transparent structure, and are easy to learn and adaptable to individual needs. The use of the computer-assisted classification systems is presented in the example of an insulator exposed to asbestos. The system of data documentation and processing has proved to be very practicable in the more than 2000 patients studied thus far.

Asbestosis↗
PubMed1997

Unemployment and cardiovascular diseases: a causal relationship?

Unemployment has become a socio-political problem of great importance in the Western industrialised countries. Although negative effects on social life and psyche resulting from unemployment are regarded as scientifically accepted today, a possible causal relationship between job loss and somatic illnesses is still a matter of controversy. A possible target organ is the cardiovascular system. The aim of this study was therefore to check by means of extensive literature analysis to what extent unemployment can be seen to influence cardiovascular morbidity. Particular attention was paid to the methods used and the clinical relevance of the results. Person-related epidemiological studies published since 1980 which investigated changes in cardiovascular risk factors associated with unemployment or prevalence rates of manifest disease influenced by unemployment were included in the final evaluation. In some cases statistically significant associations were found between unemployment and the increase in cholesterol levels or systolic/diastolic blood pressure, but the clinical relevance of such slight changes is questionable. To consider unemployment as an independent, social, cardiovascular risk factor is at present unwarranted. An increase in the prevalence rates of coronary heart disease or arterial hypertension causally linked in some studies with unemployment is scientifically questionable due to severe methodological shortcomings. On the basis of the currently available methodologically acceptable studies, the question of a quantitative contribution of unemployment to cardiovascular disease cannot be answered conclusively.

Adult↗
PubMed1997

Electrophysiological investigation of central, peripheral and autonomic nerve function in workers with long-term low-level exposure to carbon disulphide in the viscose industry.

OBJECTIVE: Neurotoxicity of carbon disulphide (CS2) is well known. The air concentration at the workplace at which such adverse effects can first be observed is the subject of controversial discussion. METHODS: In a cross-sectional study on CS2-exposed workers peripheral motor and sensory nerve conduction studies, somatosensory evoked potentials, thermotesting and investigation of forced respiration sinus arrythmia have been carried out. The data from 222 workers exposed to CS2 in the viscose industry were evaluated and compared with data from 191 employees from the same factory with similar physical and psychological stress factors but without detectable occupational contact to neurotoxic substances. Median exposure to CS2 was below the currently valid occupational-medical threshold limit value (MAK-value) of 10 ppm. Multiple linear or multiple logistic regression analysis was used to check for statistical differences. RESULTS: Binary evaluation (comparison of exposed persons versus controls after multiple linear regression) revealed a slightly lower value in the exposed group for the motor nerve conduction velocity (MNCV, -0.76 m/s, median 48 m/s), but a long way from pathological thresholds. No dose-response relationship could be found within the exposed group for any evaluation criteria of CS2-exposure. Somatosensory evoked potentials, thermotesting and analysis of heart rate variability yielded no indication of a neurotoxic effect of CS2. CONCLUSION: Isolated decrease of MNCV in binary evaluation is, with regard to the known mechanism of CS2-neurotoxicity and the lack of a dose-response relationship, obviously not due to toxic effects. We interpret our results as showing that an adverse effect of carbon disulphide at the exposure ranges found was not detectable in the exposed group.

Adult↗
PubMed1997

Interpretation criteria for standardized Western blots for three European species of Borrelia burgdorferi sensu lato.

Western blots (WBs; immunoblots) are a widely used tool for the serodiagnosis of Lyme borreliosis, but so far, no defined criteria for performance, analysis, and interpretation have been established in Europe. For the current study WBs were produced with strains PKa2 (Borrelia burgdorferi sensu stricto), PKo (Borrelia afzelii), and PBi (Borrelia garinii). To improve resolution we used gels of 17 cm in length. In a first step, 13 immunodominant proteins were identified with monoclonal antibodies. Then, the apparent molecular masses of all visually distinguishable bands were determined densitometrically. Approximately 40 bands of between 14 and 100 kDa were differentiated for each strain. From a study with 330 serum samples (from 189 patients with Lyme borreliosis and 141 controls), all observed bands were documented. To establish criteria for a positive WB result, the discriminating ability of a series of band combinations (interpretation rules) were evaluated separately for each strain (for immunoglobulin G [IgG] WB, > 40 combinations; for IgM WB, > 15 combinations). The following interpretation criteria resulting in specificities of greater than 96% were recommended: for IgG WB, at least one band of p83/100, p58, p56, OspC, p21, and p17a for PKa2; at least two bands of p83/100, p58, p43, p39, p30, OspC, p21, p17, and p14 for PKo; and at least one band of p83/100, p39, OspC, p21, and p17b for PBi; for IgM WB, at least one band of p39, OspC, and p17a or a strong p41 band for PKa2; at least one band of p39, OspC, and p17 or a strong p41 band for PKo; and at least one band of p39 and OspC or a strong p41 band for PBi. The overall sensitivity was the highest for PKo WB, followed by PBi and PKa2 WB, in decreasing order. Standardization of WB assays is necessary for comparison of results from different laboratories.

Antibodies, Bacterial↗
PubMed1997

[Nasal CPAP therapy of obstructive sleep apnea syndrome with expiratory pressure reduction: a prospective randomized study of acceptance of treatment during therapy initiation].

It is often difficult to achieve adequate acceptance of nasal continuous positive airway pressure (CPAP) therapy by patients with OSA. Many patients find it particularly inconvenient to expire against the treatment pressure. With this in mind, we have attempted to improve acceptance of CPAP therapy by using a bilevel system that reduces the treatment pressure during expiration. 52 patients were randomized either to initial treatment with CPAP therapy followed by bilevel treatment, or to treatment in reversed order. During bilevel therapy the ratio of inspiratory to expiratory pressure was fixed at 1:0.6. After each treatment the patients were interviewed on the basis of visual analogue scales to establish their subjective evaluation of such parameters as general well-being, quality of sleep, comparison of the respective treatment pressures, and possible preference for one of the two systems for long-term treatment. The minimal effective inspiratory treatment pressure during bilevel therapy (IPAP) and the minimal effective CPAP pressure were closely correlated (r = 0.89). There was no difference between the apnoea hypopnoea indices during CPAP therapy as compared with bilevel therapy. Most patients (57%) felt the treatment pressure with the bilevel system to be lower (p = 0.048). There were no differences in patients' well-being early in the morning, or in their assessment of sleep quality. The majority of patients (52%) preferred bilevel therapy for long term treatment, while 38% preferred CPAP therapy (n.s.). In a subgroup of 13 patients with a treatment pressure of > or = 10 mbar during CPAP therapy 10 patients (77%) gave preference to the bilevel system (n.s.). In a considerable number of patients the acceptance of treatment can be improved by using a bilevel system for initiation of nasal positive pressure therapy.

Adult↗
PubMed1996

Dendritic morphology of projection neurons in the cat pretectum.

The distribution and dendritic morphology of neurons in the cat pretectal nuclear complex were analyzed with respect to their projection to the ipsilateral dorsal lateral geniculate nucleus (LGNd) and the ipsilateral inferior olive (IO). Single and double retrograde tracing techniques were combined with intracellular injections of either horseradish peroxidase into electrophysiologically identified pretectal neurons or Lucifer Yellow into retrogradely labeled somata. Pretectal cells afferent to the LGNd were located in the nucleus of the optic tract (NOT), adjacent dorsal terminal nucleus of the accessory optic system (DTN), and posterior pretectal nucleus (NPP). Cells projecting to the IO were also distributed throughout the NOT-DTN and dorsal part of the NPP. Separate tracer injections (fluorogold and horseradish peroxidase [HRP] or granular blue) into the LGNd and the IO showed considerable overlap of labeled neurons in the NOT and dorsal NPP. Double-labeled neurons, however, were not observed after double tracer injections into LGNd and IO. Partial topographical segregation of the two populations was observed along the dorsoventral axis because LGNd-projecting neurons exhibited maximum density ventral to that of IO neurons. Pretectal cells to the LGNd had cell body diameters between 16 and 48 microns. Somatic shapes varied between fusiform and multipolar with considerable overlap between these two morphological appearances. Neurons projecting to the IO exhibited similar cell body sizes and their morphology also varied from fusiform to multipolar. Quantitative analysis of dendritic field size and orientation, number and order of dendritic arborizations, and symmetry of the dendritic tree revealed no statistically significant difference between the two neuronal populations. Hence, neurons of the two populations cannot be unequivocally identified just from the dendritic morphology. By contrast, dendritic morphology was correlated with the topographical location of either cell type within the pretectal nuclei rather than projection. Thus, the morphological appearance of neurons located dorsally predominantly was fusiform while neurons located ventrally mostly were multipolar.

Animals↗