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Biomedical subjects

A Hartman

Publications and source records attributed to A Hartman.

52 records · Page 3Linked to original sources
PubMed1978

Synaptic membranes from Torpedo marmorata electric organ. 1. Separation and analysis of nicotinic acetylcholine receptor- and acetylcholinesterase-containing membrane vesicles using aqueous two-phase systems.

Two-phase systems consisting of water, dextran and poly(ethylene glycol) have been used for partition of membranes obtained from Torpedo marmorata electric organ. The partition behaviour of the membranes could be adjusted by using a polymer with covalently-bound charged groups. By using this method, the membranes were divided into several fractions which were analyzed for nicotinic acetylcholine receptor and acetylcholinesterase content. It was found that nicotinic receptor-enriched membranes were separated from those containing esterase in a single partition step. Receptor-enriched membranes obtained by gradient centrifugation could be further separated into two receptor fractions by the two-phase technique. The results also reveal at least two types of acetylcholinesterase-rich membranes.

Acetylcholinesterase↗
PubMed1976

A quantitative model for partition in aqueous multiphase systems.

A model for the partition of charged molecules in aqueous multiphase systems has been developed. The partition coefficient of one component, or the overall partition coefficient of a number of components, between two arbitrary phases is expressed in terms of the difference in electrical potential between the phases (due to electrolytes present in the system), the net charges of the partitioned components and their partition coefficients in a (sometimes hypothetical) uncharged state. The fraction of material in one phase has also been described as a function of the net charges of the partitioned components. The model fits well to experimental data for partition of chromate, pyridine, ribonuclease A, two types of CO-hemoglobin and an enzyme mixture (yeast lysate) in three-phase systems consisting of poly(ethylene glycol), dextran, Ficoll and water. Minor deviations from the model are construed to be a pH-dependent uptake of ions. The data have also been used to detect differences in solvation of similar proteins, as well as the presence of several forms of some glycolytic enzymes present in yeast lysate.

Carboxyhemoglobin↗
PubMed1976

Histological aspects of DNCB sensitization and challenge tests.

I. A group of twenty-one Caucasian volunteers was patch tested without preliminary sensitization with 3, 10, 30, 50 and 90 mug 2,4-dinitrochlorobenzene (DNCB)/cm2. Of this group seven persons were read after 24 h; with one exception all showed a toxic erythematous reaction to 30 mug and higher amounts of DNCB/cm2. The other fourteen volunteers were read after 48 h. All except one reacted positively to 30 mug and higher amounts of DNCB/cm2. Histologically no changes could be noted after application of 3 and 10 mug DNCB/cm2; they started to appear in patch tests with 30 mug DNCB/cm2 or more. II. A second group of twenty-one Caucasian volunteers was sensitized with 2000 mug DNCB on a surface area of 3-14 cm2. Biopsies were performed after 1 h, 5 h, 1 day and then daily for 17 days. The histological changes occurring in the sensitization site during the primary irritant reaction of the first days were compared with the changes occurring during the flare-up reaction. No essential qualitative differences could be noted. III. Four Caucasian volunteers were sensitized with 2000 mug DNCB on 3-14 cm2. Fourteen days later challenge patch test doses of 3, 10, 30, 50 and 90 mug DNCB/cm2 were applied. Biopsies of the challenge sites were performed after 48 h. In contrast to the results in group I, histological changes could already be noted after challenge patch tests with 3 mug DNCB/cm2. The nature ofthe histological changes in primary irritant and allergic reactions to DNCB appeared to be identical and consisted of spongiosis, epidermal degeneration and lymphocytic infiltration around vessles and epidermal appendages and penetrating into the epidermal layers. It is concluded that, in order to avoid errors through misinterpretation, challenge patch tests with DNCB must be performed with low amounts, e.g. 3 or 10 mug/cm2.

Adult↗
PubMedDate not supplied

Expression of the envelope antigen of dengue virus in vaccine strains of Salmonella.

The envelope gene of dengue 4 virus (DEN) was cloned in a plasmid under the control of Escherichia coli expression signals. A clone that expressed 93% of the gene was found to be detrimental to the bacterial host. Another clone which carried only 76% of the E gene was found to be quite stable in vitro as well as in vivo. The killed recombinant bacteria induced antibodies in mice which recognized native DEN virus. Attenuated Salmonella typhimurium (SAL) strains carrying the DEN-E plasmid were tested for their efficacy as orally administered live vaccines. Protective immunization was assessed in a mouse model by immunizing three-week old BALB/c mice followed by challenge with DEN virus. It was found that these young mice were highly susceptible to the carrier SAL strains (M206 and aroA SL3261). Moreover, the SAL-infected mice were more susceptible to DEN virus challenge than control mice, suggesting that the SAL infection caused immunosuppression in these young mice.

Animals↗
PubMedDate not supplied

The retroperitoneal approach to aortic surgery associated with horseshoe kidney.

The horseshoe kidney is a rare anomaly that can significantly complicate aortic surgery. A bulky isthmus, abnormalities of renal anatomy, and a variable blood supply associated with a horseshoe kidney can pose technical difficulties in terms of aortic reconstruction. The left retroperitoneal approach affords an excellent exposure of the abdominal aorta in patients with a horseshoe kidney without dividing the renal isthmus and avoids the risk of injury to a ureter in an anomalous location. This is a case report of a patient with a horseshoe kidney who underwent a successful repair of an abdominal aortic aneurysm by a left retroperitoneal approach.

Aged↗
PubMedDate not supplied

A national profile of child welfare workers and supervisors.

Using information gained in a national survey of inservice training of child welfare supervisors and workers, the authors provide a profile of the practitioners providing child welfare services, their clientele, and their perspectives on training needs.

Adult↗