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H Christensen

Publications and source records attributed to H Christensen.

296 records · Page 17Linked to original sources
PubMedDate not supplied

Bursting strength of experimental colonic anastomoses. A methodological study.

This study was performed to evaluate the validity of the bursting strength test of experimental anastomoses. By a combination of measuring the intraluminal physiological pressure during the test procedure with a radiological detection of the anastomosed intestinal segment until disruption it was demonstrated that the bursting pressure is a meaningful parameter since the maximum pressure equals the time of anastomotic leak. At day 6 60% of the tested segments disrupted outside the anastomotic line. This indicates that the bursting strength test is not a valid measure for determining the strength of colonic anastomoses after the 4th to 5th postoperative day. Moreover, the bursting wall tension parameter was evaluated. Assessment of the anastomotic radius demonstrated significant differences when the anastomotic radius at disruption was determined from the amount of inflated contrast compared with the radius detected radiologically. These differences had the effect that the wall tension at burst compared with the wall tension determined from direct radius measurement on day 4 was 61% higher than the wall tension determined from the amount of inflated contrast with no correction for elongation of the tested segment, and 36% higher than the wall tension determined from the amount of inflated contrast and corrected for elongation of the segment. No differences in the bursting strength were found between inflation rates of 2.5 and 5.0 ml.min-1. In conclusion, the bursting strength test is a meaningful parameter since the maximum physiological pressure equals the time of anastomotic radiological disruption, and the bursting pressure is a more exact parameter for measuring the bursting strength than the bursting wall tension.

Anastomosis, Surgical↗
PubMedDate not supplied

Myofilament localization and immunoelectron microscopic detection of muscle-specific actin in neoplastic myoepithelial cells in pleomorphic adenomas and myoepitheliomas.

Elucidating the cellular characteristics of the nonluminal or myoepithelial cells of pleomorphic adenomas is one approach to establishing the diagnostic criteria for myoepitheliomas. Ultrastructural features of nonluminal tumor cells in 22 pleomorphic adenomas and of tumor cells in 9 myoepitheliomas were assessed from micrographs of routinely fixed and epoxy resin-embedded samples. Recognizable myofilaments were only moderately prominent in 1 myoepithelioma. In the rest of the cases, irrespective of whether nonluminal cells of pleomorphic adenomas or tumor cells of myoepitheliomas were spindle, angular, round, or plasmacytoid in form, myofilaments were noted only in one third of the cases and were present even in these in a small proportion of the tumor cells. Intermediate filament accumulations and basal lamina were more frequent findings associated with nonluminal tumor cells. Six pleomorphic adenomas and 2 myoepitheliomas had been fixed in half-strength glutaraldehyde and embedded in LR White resin for immunoelectron microscopic detection of muscle-specific actin. In 3 (2 pleomorphic adenomas and myoepitheliomas) of these 8 cases, readily visualized bands of filaments in many tumor cells were strongly labeled by the colloidal gold probe detecting muscle-specific actin even when myofilaments were minimal and infrequent in 2 cases and undetectable in the third by routine transmission electron microscopy. Lack of myofilament detection by immunocytochemistry or routine electron microscopy does not exclude a diagnosis of pleomorphic adenoma or myoepithelioma when growth patterns and cytology indicate such diagnoses. Immunoelectron microscopy, in fact, shows that muscle-specific actin can be detected even when myofilaments or muscle actin are apparently absent or minimal by routine electron microscopy or immunohistochemistry, respectively. Because examples of pleomorphic adenoma and myoepithelioma each with similar histologic and cytologic features of the myoepitheliomatous cells can have variable degrees or complete absence of expression of myofilaments or muscle-specific actin, the time-honored term myoepithelial for the nonluminal cells of pleomorphic adenomas and the term myoepithelioma are legitimate even in the absence of those markers that are specific for normal myoepithelial cells.

Actins↗
PubMedDate not supplied

Immunoelectron microscopy for chromogranin A in small cell neuroendocrine carcinoma of lung.

To see if immunoelectron microscopy can improve localization of neurosecretory granules, postembedding immunolabelling for chromogranin A was performed on 15 examples of small cell anaplastic (neuroendocrine) carcinomas primary in lung, five cases of bronchopulmonary carcinoids, and two cases of pheochromcytoma; both the carcinoids and pheochromocytomas had neurosecretory granule-rich cytoplasm by routine electron microscopy and some neurosecretory granules were identified in each of the small cell carcinomas. Immunolabeling for chromogranin A resulted in many colloidal gold particles over cytoplasmic secretory granules in both pheochromcytomas and four of the carcinoids. One carcinoid that was focally positive by immunoperoxidase staining was negative by immunoelectron microscopy. None of the 15 cases of small cell carcinoma stained for chromogranin A using immunoperoxidase techniques, but three had a small number of secretory granules weakly labeled by the anti-chromogranin A/colloidal gold complex. Immunoelectron microscopy, at least using standard glutaraldehyde fixation and epoxy resin embedding, does not increase the sensitivity of neurosecretory granule identification in small cell neuroendocrine carcinomas of the lung. Results of other studies of this neoplasm suggest that despite transcription of chromogranin genes, synthesis of the specific protein may occur to a limited extent or not at all.

Carcinoid Tumor↗
PubMedDate not supplied

Transient leukemia with extreme basophilia in a phenotypically normal infant with blast cells containing a pseudodiploid clone, 46,XY i(21)(q10).

PURPOSE: Transient leukemia and extreme basophilia occurred in a phenotypically normal newborn with expression of isochromosome (21)(q10) in the blast population. PATIENTS AND METHODS: A newborn boy was found to have an elevated white blood cell count of 120,800 with 33% blasts. The peripheral blood also contained elevated numbers of basophils and neutrophils with unusual staining properties. The blasts, evaluated by flow cytometry and light and electron microscopy, had the properties of megakaryoblasts. Cytogenetic studies revealed 46,XY karyotype in peripheral blood lymphocytes; however, analysis of the blast cells from the bone marrow showed an abnormal chromosome 21. RESULTS: The blast cells in the peripheral blood disappeared by day 42 without chemotherapy. The red blood cell count and platelet count normalized by 2 months. Chromosomal analysis of skin fibroblasts and bone marrow after the disappearance of the blast cells in the peripheral blood showed a 46,XY phenotype. CONCLUSIONS: The leukemic cell of transient leukemia has the potential of forming cells of basophil and megakaryocyte lineages. Trisomy of the q arm of chromosome 21 contains sufficient genetic information for the development of transient leukemia in a phenotypically normal newborn.

Basophils↗
PubMedDate not supplied

Methods for assessment of future demand of medical doctors in Denmark.

BACKGROUND: Whereas supply prognoses is mainly a matter of establishing mathematical scenarios with ongoing adjustments of variables, reliable demand prognoses are more difficult and complex to establish. However, optimum use of human and educational resources and--on the other hand--sufficient supply of medical doctors calls for reliable supply as well as demand prognoses. METHODS: Based on a number of technical and political considerations the first demand prognosis was based on three different methods; 1. Changes in demand due to demographic changes. 2. An evaluation made by the owners of the hospitals. 3. An evaluation made by the scientific medical societies. RESULTS: The demand prognosis was found to be hampered by a number of limitations. Demographic changes beyond the next 10 years was found to be unreliable. Moreover, the demand observed during the last 20 years was only to a very limited extent explained by demographic changes. The owners of the hospitals could only prognosticate for an election period, i.e. for about 5 years,--and only in very general terms that were difficult to interpretate. From some counties the answers did only seem to be based on rather superficial analysis and gave very little information. Each of the Scientific Medical Societies claimed increasing demands for the next 25 years, despite marked expectations for diagnostic and therapeutic advantageous technological developments. The overall conclusion from the combined weighed analysis was an expected increase in the demand of medical doctors of about 1% per year in the short as well as in the long term (25 years). This should be compared to the observed development during the last 10 years, i.e. an annual increase of 1.7-1.8%.

Demography↗
PubMedDate not supplied

Dimensioning of the postgraduate educational training in Denmark.

BACKGROUND: Postgraduate medical training in Denmark consists of basic training, offered to all medical doctors, followed by specialist training. The National Board of Health is responsible for the overall frame of medical training in Denmark and determines the number of trainee positions for each of the 42 specialities available. The total number of positions and their distribution between specialities are based on demand, supply and demographic considerations. Approximately 85% of medical doctors finalise specialist training. METHODS: Denmark is divided into three educational regions: North, South and East. Each region consists of counties, with their own administration. The National Board of Health approves each position for postgraduate training. All new positions and changes of existing positions are evaluated before approval by The National Board of Health. An updated version of the list of educational positions is available on the internet. CONCLUSION: The Danish governmental authorities have an efficient tool to control the dimensioning of the postgraduate medical education and thereby the production of specialists. Medical doctors can easily get information about where to obtain trainee positions. The majority of hospital departments improve their recruitment potential by participating in medical training. A number of structural changes, for instance establishing of medical centres and corporations within larger entities across an extended geographic area, specialisation between hospitals and reduced number of hospitals, calls for decentralisation of the administration in order to improve flexibility in the organisation of postgraduate medical training. However, the National Board of Health will still co-ordinate at the national level.

Denmark↗
PubMedDate not supplied

Quantification of muscular activity in the shoulder region during monotonous repetitive work.

The purpose of this preliminary study was to evaluate the degree of myoelectric activity (EMG) in the shoulder muscles during repetitive monotonous work cycles in order to assess the load on the shoulder muscles. The tasks were video recorded and the movements performed were analyzed with a direct computer-based observational method (OS-WALD). The amplitude distribution probability function (ADPF) of the surface EMG from the deltoideus lateralis and trapezius pars descendens muscles was analyzed in 6 persons working on assembly lines. For each subject, "on-site" EMG and video recordings were performed over 10-minute periods at four different workstations on the same day. Force/EMG amplitude calibration curves had been previously calculated for the same subjects using a strain-gauge dynamometer. The results obtained during the working periods were the following: the mean static contraction level, as defined by Jonsson (13), was 1.3% MVC in the trapezius muscle and 0.5% MVC in the deltoid muscle; the medium contraction level was 5.2% MVC in the trapezius and 1.7% MVC in the deltoid; the peak contraction level was 17% MVC in the trapezius and 6.2% MVC in the deltoid. When compared to previously suggested upper limits of ADPF levels, all the contraction levels monitored were below the recommended limits. The assessment of musculoskeletal load in the shoulder region via EMG and video recordings led us to conclude that the work cycles examined were characterized by low-repetitive monotonous work and were well organized in order to avoid the occurrence of musculoskeletal injuries.

Adult↗