A method for the determination of neuraminidase activity in the presence of added neuraminic acids or potential inhibitors.
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Glyoxylates↗
Biomedical subjects
L Holmquist
Publications and source records attributed to L Holmquist.
Adsorption losses of human serum apolipoproteins C and E during manipulation of diluted solutions.
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Adsorption↗
High performance concentration and gel filtration of rat urinary protein allergens.
Allergies to laboratory animals, notably rats, have become an increasingly recognized occupational problem. Identification and isolation of the individual proteins causing allergic reactions, could form the basis for early recognition of sensitivity, diagnosis, control of degree of pollution of the environment and desensibilization treatments. Frequently, allergens originate from dried rat urine. Because earlier published methods were found unsatisfactory we have developed a new strategy for isolation of rat urinary proteins including a high performance technique for their mild concentration on hydroxyapatite. The concentrated allergens have been fractionated according to molecular size by high performance gel filtration and according to carbohydrate content by wheat germ lectin-Sepharose 6 MB affinity chromatography. The obtained fractions have been examined by denaturing and non-denaturing polyacrylamide gradient gel electrophoresis followed by sensitive staining procedures, and tested with respect to allergenicity by skin tests on allergic patients.
Adult↗
Separation of glutaraldehyde and some of its aldol condensation products by hydroxyl-aldehyde group affinity chromatography.
Glutaraldehyde exists in aqueous solution in equilibrium with monomers and polymers of cyclic and open-chain hemialdals and hydrates. At alkaline pH oligomeric and polymeric alpha,beta-unsaturated aldehyde derivatives are formed from primarily produced aldol condensation products. This communication reports a method for separation of such aldol condensates by means of a new high performance liquid chromatography technique based on the affinity of aldehyde groups for hydroxyl groups of a hydroxylated polyether matrix (Bio-Gel SEC-10). Five peaks corresponding to different aldol condensates of glutaraldehyde were obtained from the affinity column. They have been distinguished by 1H-NMR and UV spectroscopy. Kinetic measurements yielded formation rates for the different aldol condensates.
Alcohols↗
Time course for the changes of serum lipoproteins and apolipoprotein T concentrations after major surgical trauma in man.
Trauma induces changes in the serum lipoprotein pattern in man. A characteristic apolipoprotein, named apolipoprotein T existing in its isoforms T-I to T-IV, in the high density lipoprotein (HDL) fraction of serum, also appears in response to trauma. In this report eight patients operated on for abdominal aortic aneurysms were studied concerning the time dependency in changes of serum lipoproteins and the appearance of apolipoprotein T. Blood samples for lipoprotein analysis were taken preoperatively, postoperatively on days 1, 2, 4, 6 and thereafter twice a week until discharge from the hospital. The serum lipoprotein concentrations were compared with those from a group of healthy men. The most striking abnormalities were found in serum VLDL where both concentrations of triglycerides and cholesterol decreased during the first 2 days by more than 50%, compared to the initial level, and remained low for about 1 week. Also the concentration of LDL cholesterol in serum decreased about 40% from the preoperative value during the first days. Serum HDL cholesterol either increased during the first 2 days in those patients with a low preoperative concentration or stayed on a subnormal level during the first 4 days. After day 4 the serum HDL cholesterol decreased and reached the minimum level on days 10 to 13. Already on day 1 after trauma apolipoprotein T had reached a high level in order to stay high for several weeks. The apolipoprotein T isoforms had different appearance with time and varied independently of serum cholesterol in HDL.
Aged↗
Round window membrane permeability. An in vitro model.
The round window membrane is regarded to be the main route for passage of potentially ototoxic substances from the middle ear cavity into the inner ear. This may be of clinical importance in acute otitis media and chronic otitis media, where sensorineural hearing impairment sometimes develops. The accuracy and reliability of an in vitro round window membrane permeability model was studied. The round window membrane of the mongolian gerbil was resected, together with its bony niche. The preparation was mounted between two glass chambers representing the middle ear and the inner ear. Passage through the round window membrane did not occur within 3 h for low density lipoprotein with a molecular weight of 2,300 kD. Only minute amounts of highly density lipoprotein, of molecular weight 115-350 kD, passed the round window membrane. The passage rate of horseradish peroxidase, which has previously been shown to pass the round window membrane in vivo, was estimated. The design of the present model is considered to make feasible controlled permeability studies on the round window membrane. Passage rates for different substances through the round window membrane can be calculated under controlled conditions by using this type of in vitro model.
Animals↗