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Biomedical subjects

S Hellem

Publications and source records attributed to S Hellem.

35 records · Page 2Linked to original sources
PubMed1983

Microvascular response in cancellous bone to halothane-induced hypotension in pigs.

The microvascular response in cancellous bone to halothane-induced hypotension was studied simultaneously using Laser Doppler Flowmetry (LDF) and clearance of locally injected 133Xe in the subapical mandibular bone of 16 young pigs. During halothane inhalation, a significant reduction in mean blood pressure to values ranging from 22 to 60 mm Hg was observed. The blood flow, as measured with LDF, increased in more than 60% of the animals with hypotension levels above 30 mm Hg. At hypotension levels below 30 mm Hg, blood flow decreased in all cases. The individual regional vascular resistance, calculated as the quotient between blood pressure and recorded blood flow value, was significantly reduced (p less than 0.001) during hypotension. Rhythmical flow variations, observed in some animals at normotension, disappeared immediately following the start of halothane inhalation, but returned when blood pressure was stabilized at a lower level. For recordings made with 133Xe-clearance, a significant reduction (p less than 0.001) in the logarithmic decay of the washout curves was observed during hypotension. This logarithmic decay was correlated to the reduced blood pressure levels (r = 0.73). No average change in regional vascular resistance could, however, be demonstrated. The lack of correlation between results obtained by the 2 methods may be due to the fact that LDF is sensitive to the total blood flow in a limited tissue volume, while the 133Xe isotope seems to be washed out mainly by the capillary blood flow. It can be further concluded that halothane-induced hypotension levels, applicable to clinical routines, may produce an increase rather than a decrease in total blood flow in cancellous bone tissue.

Animals↗
PubMed1982

Paracetamol plus supplementary doses of codeine. An analgesic study of repeated doses.

A double-blind, multicentre analgesic trial was carried out in patients suffering from pain after removal of an impacted lower wisdom tooth. 266 patients were evaluated after random allocation to treatment with paracetamol 500 mg, paracetamol 500 mg plus codeine 20 mg, paracetamol 500 mg plus codeine 30 mg, or paracetamol 500 mg plus codeine 40 mg. On the day of surgery the patients assessed their own pain intensity hourly on a visual analogue scale. The analysis of the results was carried out according to the method which considered repeated dose intake. A statiscally significant dose-response relationship was obtained between the supplementary doses of codeine and analgesic efficacy. In the comparison of side effects, their frequency increased with increasing amounts of codeine. In clinical practice codeine 30 mg appeared to be the optimal supplement for paracetamol 500 mg.

Acetaminophen↗
PubMed1981

Normal and retrograde blood supply to the body of the mandible in the dog. I. A new method for selective multicolor arterial perfusion, combined with microangiography and histology.

An experimental study was performed to evaluate a method for selective, multicolor arterial perfusion. In seven adult beagle dogs the lingual, facial and mandibular arteries on one side were cannulated and perfused selectively with different colored perfusates (Microfil and Colorpaque). Identification of the perfusates was achieved using a clearing technique combined with microradiography and histology. With this method, the vascular territories of the body of the mandible and its adjacent tissue could then be identified separately.

Angiography↗
PubMed1981

Normal and retrograde blood supply to the body of the mandible in the dog. II. The role played by periosteo-medullary and symphyseal anastomoses.

An experimental study was carried out in 8 dogs to delineate the blood supply to the body of the mandible under normal conditions and when the central (medullary) circulation was blocked. A vascular blocking technique combined with selective arterial perfusion using different colored perfusates was used. The results were based on an evaluation of cleared specimens, microradiography and histology. Under normal conditions, the inferior alveolar artery was shown to be the sole source of perfusate to the entire mandibular body, marginal gingiva and the subperiosteal layer, without any contribution from facial artery branches. Several perfused symphyseal anastomoses were found. When the medullary circulation was blocked, retrograde perfusion was evident only in the medullary bone of the frontal region 30 min. after blocking. Marked periosteal and symphyseal vascularity and an increased medullary perfusion were seen 3 days later. 30 days after vascular blocking, perfusion was demonstrated throughout the entire bone including dental pulps. The facial artery was found to be the source of the retrograde perfusion through symphyseal and periosteo-medullary anastomoses in cases with blocked central (medullary) circulation.

Angiography↗
PubMed1979

A model for evaluating the analgesic effect of a new fixed ratio combination analgesic in patients undergoing oral surgery.

A special model designed for evaluating the analgesic effect of oral analgesics was based on a short-time registration period of immediate postoperative pain. One-hour intervals in pain registration and a minimum of 2 h between the tablet intake allowed a good estimation of changes in pain levels. The patient material consisted of 112 patients and from each patient a lower impacted wisdom tooth was removed. The test model was used to compare two analgesic drugs with placebo. The two pharmacologically active preparations were Doleron (dextropropoxyphene, acetylsalicylic acid, phenazone, caffeine and Transergan) and Astra 2167 (dextropropoxyphene and acetylsalicylic acid). The trial was double blind and the tablets were administered according to a crossover design. There was no statistically significant difference in analgesic effect between Astra 2167 and Doleron, and both drugs were superior to placebo. Finally, the trial showed that a reduction of the number of components of a compound analgesic to some degree reduced the pain relieving effect on this particular postoperative pain. This observed reduction was however, not statistically significant.

Adult↗
PubMedDate not supplied

Auger electron spectroscopic studies of stainless-steel implants.

Auger electron spectroscopy together with scanning electron microscopy has been used to study the interface between stainless-steel implants and human tissue. The thickness and nature of the oxide layer on the implants have been found to depend on the location of the implants in the body. Before implantation, the oxide layer is about 50 A thick, consisting mainly of chromium oxide. For implants located in cortical bone the thickness of the interfacial oxide layer remains unaffected, while it increases by a factor of three to four on samples located in bone marrow. In both these cases calcium and phosphorus are incorporated in the oxides. Implants located in soft tissue have an interfacial oxide layer with a thickness of about one and one-half times that on an unimplanted sample. On these samples, calcium and phosphorus are not found, but occasionally sulfur is found in the oxide layer. All these samples originated from the oral region of the body; the reason for this finding, however, is not known at present time. The interactions between the implants and human tissues resulting in the observed changes of the implant surfaces are discussed in terms of oxygen pressures and metabolic activity.

Humans↗