Biomedical subjects

S Bosman

Publications and source records attributed to S Bosman.

4 recordsLinked to original sources

PubMed1995

Ultrastructural alterations in heated canine myocardium.

BACKGROUND AND OBJECTIVE: The anisotropy factor of light scattering (g) (wavelength 632.8 nm) in heated myocardium decreases as a function of temperature, suggesting, on the basis of Mie theory of light scattering, formation of an increasing number of particles with diameters smaller than the incident wavelength. STUDY DESIGN/MATERIALS AND METHODS: To test this hypothesis, fresh myocardium was heated at constant temperatures between 37 degrees C and 75 degrees C for 1,000 s. Changes in size and number of granules generated by disintegrating organelles and sarcomeres were studied as a function of temperature by transmission electron microscopy, planimetry and particle counting. RESULTS: The mitochondria started to disintegrate at 45 degrees C and myofibrils between 45 degrees C and 50 degrees C into increasing numbers of small electron dense granules (diameter 50-200 nm), which correlated with the observed decrease of g from 0.93 +/- 0.02 (at room temperature to 45 degrees C) to 0.77 +/- 0.05 at 75 degrees C. CONCLUSION: The scattering coefficient microseconds of 161 +/- 33 cm-1 did not change significantly.

Actin Cytoskeleton↗

PubMed1993

Colorectal adenomas: inflammatory changes that simulate malignancy after laser coagulation--evaluation with transrectal US.

To evaluate the assumption that inflammatory changes in the rectal wall after treatment of colorectal adenoma with photocoagulation may simulate malignant infiltration, the findings were reviewed in 23 follow-up examinations performed with transrectal ultrasound (TRUS) in 17 patients with benign adenoma. Special attention was given to the appearance of the wall layers underneath the adenoma. After partial coagulation, changes in the colorectal wall were usually seen on TRUS scans obtained early in follow-up; sometimes the thickened muscle layer had an irregular outer margin. In three of the 13 early examinations, lesions mimicked malignancy. To correlate these findings with histologic proof, an experimental study was performed: Colorectal specimens from pigs were examined with ultrasound (US) and microscopy. The abnormal sonographic appearance of specimens on US scans was caused by an inflammatory reaction in the deep wall layers; concomitant serositis appeared to be responsible for the malignancy-mimicking irregular outer margin. In screening for malignancy in colorectal adenoma, TRUS may cause overstaging during the first 6 weeks after polypectomy or after a session of laser treatment and should be avoided.

Adenoma↗

PubMed1991

Effect of percutaneous interstitial thermal laser on normal liver of pigs: sonographic and histopathological correlations.

Tumour necrosis can be induced by interstitial application of low power laser light, which causes thermal damage to the tissue. In normal pig liver the effects were studied of low power Nd:YAG laser light (continuous wave; 1.5 W, 10 min, wavelength 1064 nm), administered percutaneously via a 600 micron fibre. Ultrasound images were compared with histopathological findings. Histopathology showed induction of sharply demarcated lesions with a mean diameter of 10-15 mm (days 0 and 7), consisting of coagulative necrosis. Healing of the lesion occurred by granulation, fibrosis and removal of cell debris. Lesions could not be seen by week 4, which suggests complete regeneration. Ultrasonography showed a good correlation with histopathology, especially at 1 week when different histopathological tissue layers could be discriminated by ultrasonography. It is concluded that thermal lesions in liver can be induced via a percutaneous route and that ultrasound imaging is useful in monitoring the lesions during and after the procedure.

Animals↗

PubMed1988

[Non-invasive method of arterial oxygen saturation monitoring in the neonatal intensive care unit (with a review of blood oxygen monitoring methods)].

Recently a new method (pulse oximetry) became available, which enables us to monitor non-invasively the arterial oxygen saturation in neonates. We tested this new method in several premature infants, from the time that oxygen therapy was instituted (IPPV; CPAP), in order to evaluate its potential clinical use. In stable patients we found a better correlation (r = 0.90) between the oxygen saturation measured transcutaneously and that measured in an arterial blood sample that the correlation (r = 0.22) between oxygen tensions measured either transcutaneously or in a blood sample. Although transcutaneous monitoring of the arterial oxygen saturation, especially because it is a continuous process, can be a valuable adjunct in monitoring premature infants who receive extra oxygen, it can not replace the necessity for intermittent blood sampling to determine 'arterial blood gases'. One should also remember that; due to the fact that the position of oxyhemoglobin dissociation curve depends on several factors; the SO2 can not simply be derived from the pO2 or vice versa. Continuous transcutaneous monitoring of oxygen saturation may decrease the frequency with which arterial blood samples for blood gas measurement have to be taken.

Blood Gas Analysis↗