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Biomedical subjects

B Engström

Publications and source records attributed to B Engström.

At least 91 records · Page 5Linked to original sources
PubMed1979

Retreatment of endodontic fillings.

Effects of endodontic retreatment on quality of seal and periapical healing were assessed among 660 previously root-filled roots. The roots were divided into either of two groups according to presence or absence of pathologic alterations in the periapical area. The retreatments, which were carried out by dental students, involved a thorough chemomechanical debridement of the root-canal system aiming to control infection. Following a 2-year observation period 556 roots were reexamined clinically and radiographically. The results showed that root-fillings with technical shortcomings could, following retreatment, be markedly improved as regards effectiveness of seal and distance to the apex. A large number of lumina discernible apical to root-filling could also be treated and filled. Seventy-eight percent of the cases with pathologic lesion present periapically prior to retreatment either completely healed or displayed an obvious size-reduction of the process. Retreatments carried out because of technical inadequacies alone were successful in 94% of the cases. It was concluded that renewed endodontic treatment whenever possible is the method of choice when treating defective endodontic fillings complicated with pathologic processes periapically. Apical surgery may be attempted if no signs of healing are apparent following observation.

Adult↗
PubMed1979

The labyrinth of the American bullfrog.

The labyrinth of the American bullfrog (Rana catesbiana) has been studied by aid of light and electron microscopy. Cell counts and sensory area mapping has been made and it has been shown that scanning electron microscopy is the most appropriate technique at present for cell counts.

Animals↗
PubMed1978

Effects of milk diet on gastrointestinal absorption of cadmium in adult mice.

Effect of milk diet on absorption of cadmium were investigated in a 6-week study. Forty adult male mice were divided into groups of 10 and treated with different foodstuffs (I: mouse pellets and deionized water; II: mouse pellets and water containing cadmium chloride: III: milk only: IV: milk containing cadmium chloride). The intake of cadmium and milk was regulated during the experiment to make sure that the animal groups received the same amounts of cadmium andmilk respectively. After 2 weeks the mice were exposed to a single oral dose via stomach tube of 109CdCl2, the fate of which was followed by whole body counting. A markedly higher whole body retention of 109CdCl2 was observed in animals given milk diet compared to other groups. Total cadmium concentrations in different organs measured by atomic absorption spectrophotometry were twice as high in milk-fed mice compared to mice fed on R35 mouse pellets.

Animals↗
PubMed1978

Structure of the hairs on cochlear sensory cells.

A study of cochlear sensory hairs has been made using transmission and scanning electron microscopy. The structure of the hairs and the relation to the hair cells and to the tectorial membrane is described. A number of micrographs demonstrate both the inner structure of the hairs and their relation to the surrounding structures.

Animals↗
PubMed1978

Effects of detergent formula chelating agents on the metabolism and toxicity of cadmium in mice.

Chelating agents like NTA (nitrilotriacetic acid) STPP (sodiumtripolyphosphate, Na5P3O10) and EDTA (ethylenediaminetetraacetic acid) are used as components of detergents. An increased toxicity of some metal compounds when combined with NTA has led to decreased use of this chelating agent in relation to STPP. In the present studies short-term and long-term effects of these chelating agents on cadmium toxicity in mice were investigated. I: In the short-term study, mice subcutaneously exposed to CdCl2 (3.2 mg Cd/kg b. wt.) in combination with STPP (32 mg/kg b. wt.) demonstrated a markedly higher mortality compared to animals given CdCl2 alone. This increase in mortality was similar to the one encountered when CdCl2 (3.2 mg Cd/kg b. wt.) and NTA (32 mg/kg b. wt.) were combined. Animals exposed subcutaneously to CdCl2 + STPP or CdCl2 + NTA showed histological evidence of liver necrosis 24 hrs after exposure not seen in animals given the same dose of CdCl2 alone and also had markedly lower cadmium concentrations in the livers compared to only Cd-exposed animals. II: In the long-term study, mice were exposed orally to CdSO4 (50p.p.m Cd) alone or in combination with STPP (500 p.p.m.), NTA (500 p.p.m.) or EDTA (50 p.p.m.) by continuous administration via the drinking water for 18 months. A decreased total excretion of urine proteins was seen in all Cd-treated animals irrespectively of the combination with various chelating agents. The conclusion of the present work was the NTA and STPP given by subcutaneous injection to mice markedly increased the toxicity of cadmium but that neither NTA, STPP nor EDTA given orally altered the toxicity of cadmium during a period of long-term exposure of 18 months.

Animals↗
PubMed1976

Effect of foundry size on the dust concentration of different work phases.

The dust concentrations of different work phases in iron foundries of different sizes were studied. The results of the total dust measurements made during the Finnish Foundry Project were considered according to the eight main work phases, and the 51 iron foundries were divided into four groups according to the number of foundry workers. The division between the groups at 25, 50, and 100 workers is related to the degree of mechanization in Finnish foundries. The total dust concentration clearly increased in sand making and melting as the size of the foundry increased. The concentration decreased in molding, coremaking, knock-out, and cleaning as the number of workers increased. No significant differences between the foundry groups could be found during casting. The factors affecting the differences in dust concentrations are discussed.

Air Pollutants↗
PubMed1976

Dust exposure in Finnish foundries.

Dust measurements were made in 51 iron, 9 steel, and 8 nonferrous foundries, at which 4,316 foundrymen were working. The sampling lasted at least two entire shifts or work days continuously during various operations in each foundry. The dust samples were collected at fixed sites or in the breathing zones of the workers. The mass concentration was determined by weighing and the respirable dust fraction was separated by liquid sedimentation. The free silica content was determined by X-ray diffraction. In the study a total of 3,188 samples were collected in the foundries and 6,505 determinations were made in the laboratory. The results indicated a definite difference in the dust exposure during various operations. The highest dust exposures were found during furnace, cupola, and pouring ladle repair. During cleaning work, sand mixing, and shake-out operations excessive silica dust concentrations were also measured. The lowest dust concentrations were measured during melting and pouring operations. Moderate dust concentrations were measured during coremaking and molding operations. The results obtained during the same operations of iron and steel foundries were similar. The distribution of the workers into various exposure categories, the content of respirable dust and quartz, the correlation between respirable dust and total dust, and the correlation between respirable silica and total dust concentrations are discussed. Observations concerning dust suppression and control methods are briefly considered.

Air Pollutants↗
PubMed1975

Morphological studies of the rat small intestine after jejuno-ileal transposition.

The small intestine of the rat was studied by light, fluorescence, transmission electron and scanning electron microscopy after jejuno-ileal transposition. No systematic cell damage in the wall layers of the transposed intestine was observed. Two and 12 weeks postoperatively the villi of the transposed ileum were significantly higher than in the ileum of both sham-operated animals and intact controls. In corresponding comparisons the transposed jejunum also exhibited slightly higher villi 2 weeks postoperatively, but this difference had decreased 10 weeks later. The length and breadth of the villi appeared to be less affected by the operation. In comparison with corresponding sham-operated and intact animals the epithelial cells along the villi in the transposed ileum were initially increased in number per mm basement membrane, but later decreased.

Animals↗