Biomedical subjects
L Jansson
Publications and source records attributed to L Jansson.
Macromolecular properties and end-group analysis of heparin isolated from bovine liver capsule.
Glycosaminoglycans were extracted from bovine liver capsule with 4 M-guanidinium chloride, resulting in solubilization of approx. 90% of the total uronic acid-containing polysaccharide of the tissue. The extracted polysaccharide was purified and fractionated by anion-exchange chromatography on DEAE-cellulose, density-gradient ultracentrifugation in CsCl and finally gel chromatography on Sepharose 4B. By using these procedures, the two major polysaccharide components, dermatan sulphate and heparin, which constituted 55 and 30% respectively of the total glycosaminoglycan content of the tissue, were separated from each other. Analysis of the macromolecular properties of the two polysaccharides showed that heparin existed exclusively as single polysaccharide chains, whereas dermatan sulphate occurred largely as a proteoglycan (protein content, 74% dry wt.). The purified heparin preparation was subjected to sedimentation-equilibrium ultracentrifugation, indicating a molecular weight of 8800. Analysis for neutral sugars (by g.l.c.) showed 0.1 residue of xylose and 0.2 residue of galactose/polysaccharide chain; serine amounted to 0.3 residue/polysaccharide chain. Reduction of the heparin with NaB3H4 resulted in incorporation of 3H, approximately corresponding to one reducible group/polysaccharide chain. The 3H-labelled sugar residue was liberated by a combination of acid hydrolysis and deaminative cleavage of the polysaccharide with HNO2; it was subsequently identified as an aldonic acid by paper electrophoresis. Most of the heparin chains thus contained a uronic acid residue in reducing position. It is suggested that heparin isolated from bovine liver capsule is a degradation product released from larger molecules by an endo-glycuronidase.
Biosynthesis of heparin. Solubilization and partial characterization of N- and O-sulphotransferases.
Assay methods were developed enabling separate determination of N- and O-sulphotransferase activities in an enzyme preparation from mouse mastocytoma. N-Desulphoheparin and chemically N-acetylated heparan sulphate were used as specific exogenous sulphate acceptors in the transfer of [35S]sulphate residues from adenosine 3'-phosphate 5'-[35S]sulphatophosphate to amino and hydroxyl groups respectively. The resulting 35S-labelled polysaccharides were isolated as their cetylpyridinium complexes on filter paper. Sulphotransferases were solubilized from a mastocytoma microsomal fraction by treatment with detergent-alkali. The pH optimum for both enzymes was about 7.5 Km with regard to adenosine 3'-phosphate 5'-sulphatophosphate was estimated to be 2 X 10(-5) M for the N-sulphotransferase and 1 X 10(-4) M for the O-sulphotransferase(s). The enzymes required bivalent cations for maximum activity, Mn2+ stimulating both the N- and O-sulphotransferase four- to five-fold, whereas Ca2+ increased the N- but not the O-sulphotransferase activity. The O-sulphotransferase was found to be more sensitive to heat-inactivation, 60% of the activity being lost after 1 min at 50 degrees C, whereas only 15% of the N-sulphotransferase activity was lost. In contrast, the N-sulphotransferase was selectively inhibited (or inactivated) by NaCl; at 0.125 M-NaCl concentration the O-sulphotransferase activity was essentially unaffected, whereas the N-sulphotransferase activity was depressed by 80%. These results strongly indicate that N- and O-sulphate-transfer reactions should be ascribed to different enzymes, or, alternatively, to separate and independent active sites on the same enzyme molecule.
Noise reduction of ECG by averaging. An experimental study of the procedure and a validated method.
Electrical noise often hampers the interpretation of ECG and other heart-synchronous signals. Time-coherent averaging is a commonly used method to reduce the noise. This method has been implemented on a computer with 12,000 12-bit words of core memory, suitable for on-line use in any clinical laboratory. An analysis was made of which demands apply to the exactness of synchronization of added heart cycles. The method was tested with respect to these demands and also, on a limited scale, for its efficiency in eliminating ectopic beats from the average.
Electronic timing of a high-speed immunonephelometric continuous-flow system.
We describe a high-speed immunoephelometric continuous-flow system. The mechanical timing asembly and cams of the sampler were replaced by an external electronic control unit. Improved sampling precision, speeds of 2 to 900 samples per hour, and a wide variety of sample-to-wash ratios are the most important advantages of the unit. We analyzed albumin and fibrinogen at speeds of 150, 180, and 210 samples per hour. Carry-over studies showed that, in clinical practice, it should be possible to run the system at 150 samples per hour with an interaction of less than 5% and a precision (CV) of around 4%. Comparative studies with a previously described method, run at 60 samples per hour, showed correlation coefficients of 0.968 and 0.935 for albumin and fibrinogen, respectively. The electronic control unit can be used to increase speed and improve sampling precision of any continuous-flow system. An immunonephelometric system equipped with this device provided fast and reliable results, and required less antiserum than other systems described.
A method for studies of airway closure in relation to lung volume and transpulmonary pressure at a regulated flow rate.
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Biosynthesis of heparin. II. Formation of sulfamino groups.
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A theoretical study on flow patterns of ventilators.
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Evidence for the existence of a multichain proteoglycan of heparan sulphate.
1. Glycosaminoglycans were extracted with 2m-potassium chloride from bovine aorta and purified by precipitation with cetylpyridinium chloride from 0.5m-potassium chloride. The yield amounted to 24% of the total glycosaminoglycan content of the tissue. 2. After removal of chondroitin sulphate by digestion with testicular hyaluronidase, the residual glycosaminoglycan material (11% of the extracted polysaccharide) was fractionated by gel chromatography on Sephadex G-200. Two peaks (I and II) were obtained, the more retarded of which (II) corresponded to single polysaccharide chains. 3. The macromolecular properties of fraction I were investigated by repeated gel chromatography, after treatment of the fraction with alkali or digestion with papain. In both cases the elution position of fraction I was shifted towards that of the single polysaccharide chains. 4. Analysis of fraction I showed approximately equal amounts of heparan sulphate and dermatan sulphate. It is concluded that these glycosaminoglycans both occur in the aortic wall as multichain proteoglycans.
Porcine islet-like cell clusters cure diabetic nude rats when transplanted under the kidney capsule, but not when implanted into the liver or spleen.
The ability of porcine islet-like cell clusters (ICC) to cure diabetic nude rats after transplantation (tx) into one of three different implantation sites was investigated. Streptozotocin-diabetic (50 mg/kg BW) nude Rowlett rats were transplanted with 40 microliters of packed ICC (approximately 4500 ICC) either under the kidney capsule, intraportally, or into the spleen. After transplantation the rats were treated with insulin every second day; insulin therapy was discontinued four days before blood glucose determinations (6, 8, 12 and 16 wk after tx) or when graft function was obtained. Six weeks after tx all rats implanted under the kidney capsule (n = 13) had blood glucose concentrations which were significantly lower than before transplantation. However, six of these rats slowly returned to hyperglycemia, whereas seven rats remained normoglycemic with normal intraperitoneal glucose tolerance tests. The return of hyperglycemia seen in some of the rats transplanted under the kidney capsule may be due to rejection, since older nude rats may show a development of T lymphocytes. After nephrectomy in four of these rats, all reverted to hyperglycemia. The rats transplanted intraportally (n = 9) or into the spleen (n = 6) remained hyperglycemic throughout the study (16 wk). It is concluded that porcine islet-like cell clusters cure diabetic nude rats when transplanted under the kidney capsule, but not when implanted into the liver or spleen.
Striving for becoming at-home in the midst of dying.
Research interviews with 12 patients at an inpatient, free-standing hospice in Sweden were analyzed, using a phenomenological hermeneutic approach, to show the effects of individual nursing care as experienced by the guests. The findings revealed that the effects of, and reactions to, nursing care were inseparable from the hospice milieu and the patients' situation, which was interpreted as including the prospect of becoming homeless. Thus, the effects of hospice spirit (nursing care and milieu) as experienced by these hospice patients represented the contrasting possibilities of hindering--or contributing to--the prospect of becoming homeless. What the patients spoke about was either a consoling or a desolating hospice spirit. A consoling hospice spirit supports experiences of wholeness and communion, i.e., becoming at-home in the midst of dying, while a desolating hospice spirit results in feelings of alienation and fragmentation, i.e., feeling homeless. Considering the dying person to be a guest rather than a patient is an important component of Swedish hospice philosophy and supports the view of the dying person as an autonomous and dignified human being.
Influence of adrenaline on blood perfusion and vascular conductance of the whole pancreas and the islets of Langerhans in the rat.
The blood perfusion and vascular conductance of the whole pancreas and of the islet organ were measured separately with the aid of a microsphere technique after intravenous infusion (0.1 ml/min) of adrenaline in different doses (1, 2 or 3 micrograms/kg body weight x min). Control animals were infused with saline alone and had a mean arterial blood pressure of approximately 100 mm Hg. Adrenaline increased the mean arterial blood pressure to 150, 175 and 200 mm Hg, respectively. A decrease of both whole pancreatic blood flow and islet blood flow could be seen after adrenaline administration, but no differences were observed between the two highest doses (greater than 2 micrograms/kg body weight x min of adrenaline). The fraction of blood diverted through the islets was approximately 10% of the whole pancreatic blood flow in all experimental groups. Also the vascular conductance decreased more than the blood perfusion values. It is concluded that adrenaline produces a decrease of blood flow to both the islets and the whole pancreas, which is similar in both the endocrine and exocrine tissue.
Collagen induced arthritis: an experimental model for rheumatoid arthritis with involvement of both DTH and immune complex mediated mechanisms.
The type II collagen induced arthritis animal model (CIA) provides opportunities to study the nature of autoimmune reactions leading to arthritis and is also a useful model for rheumatoid arthritis (RA). Thus, in similarity with RA, the CIA when induced with autologous type II collagen, shows a chronic and progressive disease course. The susceptibility to both RA and CIA are correlated to the expression of certain MHC class II allotype genes. In both diseases autoantibodies to type II collagen and rheumatoid factors are produced. Immunohistopathology of affected joints show in both diseases a dominance of activated macrophages/fibroblasts with a significant infiltration of activated T cells. We suggest here that both RA and CIA are dependent on a synergy between delayed type hypersensitivity and immune complex mediated inflammatory mechanisms and that CIA could provide a tool for studies of immunospecific reactions leading to arthritis.
The protective effect of glucose, but not 3-O-methyl glucose, against alloxan-induced diabetes depends upon the route of hexose administration.
It is well established that pretreatment with glucose prevents the development of alloxan-induced diabetes in rodents. This was confirmed in the present study, and a protective effect against the development of hyperglycemia, after alloxan administration (75 mg/kg body weight), in male NMRI mice was observed when glucose was injected i.v. 10 or 20 min before alloxan injection. However, when glucose was administered i.p., a protective effect was only observed when glucose was given 20 min before alloxan, despite the fact that the serum glucose concentrations at the time of the alloxan injection were similar in the i.v.- and i.p.-injected animals. Administration of 3-O-methyl glucose by i.v. and i.p. routes protected against the effects of alloxan to the same extent. When alloxan was administered at a lower dose (65 mg/kg body weight) both i.v. and i.p. administration of glucose 10 min before alloxan, protected against the development of hyperglycemia. It is concluded that the route of administration of glucose, but not of 3-O-methyl glucose, affects its protective action against alloxan-induced diabetes. The present findings suggest that an important feature of the glucose mediated protection against alloxan-induced diabetes is the metabolism of glucose within the B-cells, rather than via extracellular effects on the B-cell plasma membrane.
Experimental pancreatic transplantation in diabetes.
Although transplantations of vascularized pancreas in diabetic patients show steadily improving results, the immediate operative risks and life-long immunosuppressive medication involved represent considerable disadvantages. Efforts are being made to develop simpler and safer methods of transplantation with isolated pancreatic islet grafts, e.g., isolated islets, fetal pancreas, or dispersed adult pancreas. Iso-, allo-, and xenografts of such preparations have been shown to reverse diabetes in animals. However, attempts to apply these techniques in clinical practice have remained largely unsuccessful, and major technical advances are needed before success is achieved. Attempts to use whole, segmented, or isolated islets from pancreatic grafts as a cure for diabetes in animals and in diabetic patients are reviewed. The importance to the graft's permanent function, of adequate preparation and storage of the graft, and of beta-cell growth and vascularization are reviewed. Various forms of immunomodulation by pretreatment of grafts in vitro have been employed in animal models of diabetes, but none of these have yet been employed with long-term success in humans. Recurrence of a specific autoimmune response toward the beta-cell in a spontaneously diabetic recipient is a potential mechanism for destruction of transplanted islet tissue.
A charcoal sampling method and a colorimetric analytical procedure for carbon disulfide. Measurement data from a viscose rayon manufacturing plant.
A charcoal sampling method and a colorimetric analytical method for carbon disulfide were developed. The methods were validated at relevant concentration of CS2. Precision and accuracy were acceptable (23%-6% and 36%-1%) at 25-400 micrograms CS2 deposited on the solid sorbent. The methods were calibrated with charcoal tube sampling and GC-FPD analysis. Regression analysis was performed on duplicate samples and a correlation coefficient of 0.96 and a regression coefficient of 0.8 were obtained. Occupational hygiene measurements were performed in a rayon manufacturing plant. A great proportion of TWA concentrations exceeded the swedish TLV (16 mg/m3) at all sample sites.
Isovolemic hemodilution and pancreatic islet blood flow in the rat.
Adult rats were isovolemically hemodiluted with isotonic dextran-solutions to reduce the hematocrit by approximately one third. This procedure decreased the mean arterial blood pressure but markedly increased cardiac output. The serum glucose concentration was increased, whilst the serum insulin concentration remained unchanged. The blood flow values and the vascular conductances of both the whole pancreas and the islets were reduced by 40-60% by hemodilution. However, the decrease in islet blood flow was less affected as indicated by the increase in the percentage fraction of whole pancreatic blood flow diverted through the islets (13.5 +/- 0.7% compared to 9.7 +/- 0.8%; p < 0.05). It is concluded that isovolemic hemodilution, despite a markedly increased cardiac output, decreased both whole pancreatic blood flow and islet blood flow.