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Biomedical subjects

J Jensen

Publications and source records attributed to J Jensen.

At least 343 records · Page 19Linked to original sources
PubMed1990

[Arthroscopy and arthroscopic surgery of the temporomandibular joint].

Diagnostic arthroscopy and arthroscopic surgery of the TMJ has during the recent years been introduced in the treatment of internal derangements, preauricular pain and osteoarthrosis of the TMJ. In closed lock cases and in cases with preauricular pain a satisfactory result of treatment has been described in 80-90% of cases, where there was lacking effect of conservative treatment with splints and physiotherapy. The refinement in the technique has made it possible to use rotating instruments, cauterisation and to perform suturing through the arthroscopic cannula and in this way reduce the need for open joint surgery. Due to the technique only few complications have been reported. In the Department of Oral and Maxillofacial Surgery in the University Hospital of Aarhus arthroscopy of the TMJ was introduced 1 1/2 year ago and 22 patients with the clinical diagnosis closed lock or preauricular pain or a combination of these has been treated during this period. The results are satisfactory in most cases and are comparable with previously published results.

Arthroscopy↗
PubMed1990

[Use of titanium osteosynthesis in maxillofacial traumatology and orthognathic surgery].

This paper reviews the clinical use of titanium miniplate osteosynthesis in maxillofacial traumatology and orthognathic surgery. These materials were originally developed for treatment of mandibular fractures, but the application has within recent years been extended to other fractures of the facial skeleton and orthognathic surgery. The osteosynthesis increase stability in many situations, and may reduce or eliminate the need for post-operative intermaxillary fixation, by which morbidity, hospitalization period and period of sick-leave can be reduced. In orthognathic surgery, the stability of the miniplate osteosynthesis increase the demand for precision during surgery as compared to conventional fixation with wire osteosynthesis and intermaxillary fixation. Further refinements of the technique are, however, necessary in the future, as the current techniques does not always allow a sufficient reproduction of the position of the condylar segment.

Bone Plates↗
PubMed1990

Osteoradionecrosis, pathogenesis, treatment and prevention.

The present paper discuss the development of osteoradionecrosis (ORN) in the jaws. ORN is the end stage of tissue injury induced by irradiation. The most prominent etiologic factor of ORN seems to be the effect of radiation on endothelial cells lining the vessels. These cells are, as tumor cells, highly radiosensitive, and radiation leads to a vascular damage resulting in hypoxic, hypovascular and hypocellular tissues. Wound healing in such tissues is impaired since nutritional demands of the wound, including oxygen, cannot be supplied due to the degenerative changes in the blood vessels. The paper furthermore describes the scientific basis for the use of hyperbaric oxygen therapy (HBO) in ORN. HBO increase the vascularity in the tissues injured by radiation, and thus tissue viability and healing capacity is increased reducing the risk for spontaneous or traumainduced ORN. Protocols for the treatment of patients with ORN are presented and prophylactic guidelines are described.

Adult↗
PubMed1990

Detection of bovine viral diarrhea virus genome in leukocytes from persistently infected cattle by RNA-cDNA hybridization.

A bovine viral diarrhea virus (BVDV) cDNA library was constructed. One cloned complementary DNA sequence was used as a probe to detect BVDV RNA by hybridization in infected cell cultures and in mononuclear leukocytes from persistently infected cattle by dot blot and in situ hybridization. The cDNA probe hybridized with all cytopathic and noncytopathic BVDV isolates tested. The hybridization results were consistent with results obtained using conventional subculturing and immunofluorescent staining methods and by inoculation of seronegative test cattle.

Animals↗
PubMed1990

Methylmalonic acid concentrations in serum of normal subjects: biological variability and effect of oral L-isoleucine loads before and after intramuscular administration of cobalamin.

The clinical value of measuring concentrations of methylmalonic acid in serum (S-MMA) as an aid in the diagnosis of cobalamin deficiency has recently aroused interest. In 58 healthy subjects, ages 40-68 years, we found a 0.95 reference interval of 0.05-0.37 mumol/L (mean 0.21, SD 0.094). In 33 of the subjects, who were studied further, day-to-day variation (SD) was 0.031 mumol/L. Intake of food had no effect. Weekly and three-monthly intra-individual variations were both 0.038 mumol/L. In all seven subjects with S-MMA greater than 0.30 mumol/L, the concentrations declined significantly after intramuscular administration of cobalamin. No significant difference was found between mean serum cobalamin concentrations in these seven and in the remaining subjects. We have also established the normal response of S-MMA to standardized oral loading of L-isoleucine: 100 mmol caused a significant average S-MMA increase of 0.072 mumol/L before cobalamin administration vs 0.013 mumol/L after cobalamin, without significant relation to initial S-MMA values. Our results provide a necessary background for interpretation of S-MMA measurements in clinical studies.

Administration, Oral↗
PubMed1989

A model for the stepwise radiation inactivation of the alpha 2-dimer of Na,K-ATPase.

This study is a direct continuation of Jensen, J., and Nørby, J. G., (1988) J. Biol. Chem. 263, 18063-18070. A new model in which we propose that the in situ organization of the Na,K-ATPase alpha-subunit is an alpha 2-dimer and which describes the stepwise degradation by radiation inactivation of this assembly is presented on the basis of the following findings. Radiation inactivation size for alpha-peptide integrity, normal nucleotide, vanadate and ouabain binding, and K-pNPPase activity is close to m(alpha) = 112 kDa; for Na-ATPase activity it is 135 kDa and for Na,K-ATPase activity it increases from 140 to about 195 kDa with increasing assay ATP concentration (equal to increasing average turnover). Normal Tl+ occlusion had the same radiation inactivation size as Vmax for Na,K-ATPase, i.e. about 195 kDa. The binding experiments disclosed radiation-produced molecules with active binding sites but with a lower than normal affinity. Radiation inactivation size for the total binding capacity of ADP and ouabain was therefore smaller than the size of an alpha-peptide, namely about 70 kDa, and for total Tl+ occlusion it was down to 40 kDa. We can explain all these observations by using a new approach to target size analysis and by assuming a dimeric organization of the alpha-subunit. Each alpha-peptide is degraded stepwise by first destruction of either a 42- or a 70-kDa domain, and the partly damaged peptide may retain biochemical activity. We conclude that there is no role for the beta-subunit in catalysis and that the alpha-peptide is organized as an alpha 2-dimer in the membrane with each alpha-subunit being able to perform complete catalytic cycles (and probably also active transport), provided that it is stabilized by an adjacent alpha-peptide or a sufficiently large fragment thereof.

Animals↗
PubMed1989

Thallium binding to native and radiation-inactivated Na+/K+-ATPase.

The number of high-affinity K+-binding sites on purified Na+/K+-ATPase from pig kidney outer medulla has been assessed by measurement of equilibrium binding of thallous thallium, Tl+, under conditions (low ionic strength, absence of Na+ and Tris+) where the enzyme is in the E2-form. Na+/K+-ATPase has two identical Tl+ sites per ADP site, and the dissociation constant varies between 2 and 9 microM. These values are identical to those for Tl+ occlusion found previously by us, indicating that all high-affinity binding leads to occlusion. The specific binding was obtained after subtraction of a separately characterized unspecific adsorption of Tl+ to the enzyme preparations. Radiation inactivation leads to formation of modified peptides having two Tl+-binding sites with positive cooperativity, the second site-dissociation constant approximating that for the native sites. The radiation inactivation size (RIS) for total, specific Tl+ binding is 71 kDa, and the RIS for Tl+ binding with original affinity is approx. 190 kDa, equal to that of Na+/K+-ATPase activity and to that for Tl+ occlusion with native affinity. This latter RIS value confirms our recent theory that in situ the two catalytic peptides of Na+/K+-ATPase are closely associated. The 71 kDa value obtained for total Tl+ sites is equal to that for total binding of ATP and ADP and it is clearly smaller than the molecular mass of one catalytic subunit (112 kDa). The Tl+-binding experiments reported thus supports the notion that radiation inactivation of Na+/K+-ATPase is a stepwise rather than an all or none process.

Animals↗
PubMed1989

[Running injuries sustained in a marathon race. Registration of the occurrence and types of injuries in the 1986 Arhus Marathon].

A questionnaire investigation was undertaken in connection with the Arhus Marathon Race in 1986, with the object of registering experience, previous running injuries, amount of training, running injuries, treatment and causes. A total of 831 replies were obtained (90%). Of these, there were 731 men and 100 women with an average age of 34.6 (11-77) years, duration og training 5.5 months, training distance 47.5 km/week and tempo 10.8 km/hour. Among these, 193 injuries were registered in 161 runners (19%). Eighty-nine had to stop sports for more than one week and 26 still had injuries which limited participation in sport after eight weeks. The injuries consisted of blisters (25%) and stress injuries (66%) particularly in the knee (37%) and leg (23%). Runners who sustained injuries were found to be significantly younger than non-injured runners, their training distance was less and training tempo lower. The causes of the injuries were mainly overexertion. The significance for the types of shoes for stress injuries was investigated and a tendency to increased risk of overexertion injuries was demonstrated on employing competition shoes and cheap jogging shoes.

Adult↗
PubMed1989

[Patellar fractures. Modified tension band osteosynthesis].

In a retrospective investigation, the ability of modified tension band osteosynthesis to retain 45 reduced fractures of the patella and the functional end result was studied. Postoperatively, 24 patients were immobilized in plaster casts for 0-14 days and the remainder for 25-56 days. Postoperative radiographs revealed nine fractures (four transverse, three comminuted and two pole fractures) with fragment displacements exceeding 2-3 millimeters. Among these, three fractures had secondary dislocation and, further, one exactly reduced pole fracture dislocated. Operation was complicated with infection in four cases: two superficial wound infections, one subcutaneous fistula and one pyarthron. Operative release of adhesions was performed in five cases, two patients were patellectomized and one required a condyle prosthesis. At follow-up 18-80 months after the injury, 37 patients were examined clinically. Among 29 patients without concomitant injuries, seven patients were free of symptoms and 13 patients were without any pain. Free knee movement and quadriceps atrophy less than or equal to 1.5 cm was found in 17 patients. The modified tension band can retain adequately reduced transverse and comminuted fractures of the patella, probably also without plaster immobilisation. Dislocated fracture of the patella is a serious lesion, which must be treated with care.

Adolescent↗