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Biomedical subjects

B A Hansen

Publications and source records attributed to B A Hansen.

85 records · Page 5Linked to original sources
PubMed1979

Clinical methods in smoking cessation: description and evaluation of a stop smoking clinic.

This study reports the results of the Kaiser-Permanente Stop Smoking Clinic and describes the philosophy and methods employed by the clinic in treating addictive smoking behavior. Of the 1,128 clients who registered for the group program, 57 per cent are abstinent six months after quitting smoking and 47 per cent are abstinent at one year. The clinic methods used are described in detail. They attempt to relate smoking behavior to the larger phenomenon of addiction.

Adult↗
PubMed1978

Impacted fractures of the femoral neck treated by early mobilization and weight-bearing.

Among 280 patients with femoral neck fractures 46 were classified as having impacted fractures according to the criteria mentioned below. The treatment of patients with impacted femoral neck fractures was determined to be mobilization with partial weight-bearing from the first day of admission. Among the 42 patients successful in immediate mobilization there were eight whose fractures disimpacted. Three cases of avascular necrosis were recorded but no cases of non-union. In order to determine the predictive signs of secondary dislocation the X-ray findings were subjected to statistical analysis. The inclination of the fracture line, dislocation into a valgus or varus position and the presence of retroversion did not influence the tendency to disimpaction. More than 80 per cent of the fractures healed without disimpaction.

Aged↗
PubMed1977

Sulfhydryl groups in relation to the structure and catalytic activity of 2-oxo-4-hydroxyglutarate aldolase from bovine liver.

Bovine liver 2-oxo-4-hydroxyglutarate aldolase (suggested name: 2-oxo-4-hydroxyglutarate glyoxylate-lyase catalyzing the reaction: 2-oxo-4-hydroxyglutarate in equilibrium pyruvate + glyoxylate) contains eight to ten sulfhydryl groups as determined by titration of the enzyme with either 5,5'-dithiobis(2-nitrobenzoic acid) (Nbs2) or p-mercuribenzoate in the presence of 1% sodium dodecyl sulfate. In the absence of a denaturant, all of the cysteinyl residues react with p-mercuribenzoate whereas only four are accessible to titration with Nbs2. No differences in -SH group reactivity can be detected during titration of the aldolase with p-mercuribenzoate. In contrast, two classes of sulfhydryls can be differentiated in the disulfide exchange reaction with Nbs2 in the absence of a denaturant; one -SH group (Class I) reacts rapidly whereas three additional thiols (Class II) titrate at approx. 0.1 the rate of the Class I-SH residue. Both pyruvate and glyoxylate protect one of the three -SH residues in Class II from reaction with Nbs2. Either substrate also prevents titration of one to two thiol groups by p-mercuribenzoate and decreases the rate of reaction of aldolase -SH groups with Nbs2 in 8 M urea. These ligand-induced changes in -SH reactivity provide a sensitive indication that the enzyme exists in an altered conformational state in the presence of either of its cosubstrates. Titration of the enzyme with either Nbs2 or p-mercuribenzoate results in a progressive loss of aldolase activity which is not proportional to the number of -SH groups modified. The enzyme retains 50% of the activity of the native enzyme when Class I and Class II thiols (i.e. four -SH groups total) are modified with Nbs2; 15% residual activity is still observed following titration of all of the cysteinyl residues with p-mercuribenzoate. Pyruvate and glyoxylate provide partial protection against inactivation. It is concluded that inactivation of 2-oxo-4-hydroxyglutarate aldolase by Nbs2 or p-mercuribenzoate is a consequence of alterations in protein structure which accompany modification of -SH groups. The data argue against the direct participation of an active-site thiol group in the catalytic mechanism of 2-oxo-4-hydroxyglutarate aldolase, be that aldol cleavage and condensation or beta-decarboxylation.

Aldehyde-Lyases↗
PubMed1976

Inactivation of bovine liver 2-keto-4-hydroxyglutarate aldolase by cyanide in the presence of aldehydes.

Kinetic data show that the irreversible inactivation of liver 2-keto-4-hydroxyglutarate aldolase observed when the enzyme is incubated with an aldehydic substrate (or substrate analogue) in the presence of cyanide is a biphasic process and can, under certain conditions, involve a direct interaction between the enzyme and cyanide. The kinetic data are consistent with a scheme consisting of three competing reactions: (1) irreversible addition of cyanide to the enzyme-substrate Schiff base intermediate, (2) reversible cyanohydrin formation between cyanide and the aldehydic substrate (or substrate analogue), and (3) an interaction of cyanide with the enzyme which is not substrate dependent. Approximately 0.4 mol of cyanide is associated with 1 mol (120 000 g) of enzyme when 2-keto-4-hydroxyglutarate aldolase is incubated with [14-C]-cyanide followed by exhaustive dialysis; an ionic attachment possibly at a carboxylate binding site, is suggested. Whereas native enzyme, not treated with cyanide, has ten Nbs2-titratable sulfhydryl groups, approximately one less such group reacts with Nbs2 when the aldolase is incubated with cyanide (in the absence of aldehydic substrate). It is suggested that the binding of cyanide results in a conformational change of the enzyme; conformational changes in the presence of cyanide are confirmed by circular dichroism spectra.

Animals↗
PubMed1976

Fractures of the tibia in children.

A total of 102 children, aged 1-15 years, treated for fissures, infractions, and fractures of the tibia were studied to elucidate the influence of age, type of fracture, and mechanism of trauma upon the course of union. In addition, an assessment was made of the possibilities the child has of correcting deformities of the diaphysis during continued growth. Eight-five of the children were followed up clinically and radiologically. The time taken for union to occur increased with increasing age. The "high energy" injuries were found to be more apt to cause transverse and comminuted fractures, with injury to the skin, than the "low energy" fractures. At the time of union, 25 patients had angular deformities. The mean correction of this deformity up to the time of follow-up was only 10 per cent. The tendency to correct the deformity ceased 18 months after the accident, and was independent of the child's age at the time of the accident.

Adolescent↗
PubMed1975

Peripheral nerve injury as a complication of axillary arteriography.

Five patients with peripheral nerve injury after axillary arteriography are presented. The clinical and electromyographic pictures of this complication are described. In 4 patients the brachial plexus was damaged due to haematoma or pseudoaneurysm-formation at the site of the arterial puncture. The grave prognosis for this complication is illustrated on the basis of the literature and our cases. Since it is concluded that the prognosis is better if rapid surgical correction of the complication is performed, certain steps to prevent the disabling outcome are proposed.

Adolescent↗
PubMedDate not supplied

Xylitol normalizes the accelerated hepatic capacity for conversion of amino nitrogen to urea nitrogen in diabetic rats.

In diabetes, the capacity of urea nitrogen synthesis, ie, a substrate-independent measure of the hepatic conversion of amino nitrogen to urea nitrogen, is increased. Xylitol decreases urea synthesis in normal rats. Capacity of urea nitrogen synthesis and nitrogen balance were measured during intravenous alanine loading in control rats, rats with experimental diabetes (streptozocin 75 mg/kg), and rats with experimental diabetes infused with xylitol to 1 mmol/L. In control rats, capacity of urea nitrogen synthesis was 9.4 +/- 1.1 mumol/min per 100 g of body weight, and nitrogen balance -2.7 +/- 1.2 mumol/min per 100 g of body weight. In the diabetics, these values were markedly increased to 26.6 +/- 1.9 and -16.3 +/- 2.1 mumol/min per 100 g of body weight, respectively (p < 0.01). The infusion of xylitol normalized these values to 11.2 +/- 1.0 and -3.6 +/- 2.1 mumol/min per 100 g of body weight for capacity of urea nitrogen synthesis and nitrogen balance, respectively. Xylitol did not change glucagon or insulin. Xylitol improved the nitrogen economy of uncontrolled diabetic rats by decreasing urea synthesis. The mechanism is not settled, but it does not involve insulin or glucagon.

Amino Acids↗