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Biomedical subjects

B Andersson

Publications and source records attributed to B Andersson.

At least 541 records · Page 30Linked to original sources
PubMed1976

Separation of subchloroplast membrane particles by counter-current distribution.

Counter-current distribution in an aqueous Dextran-polyethylene glycol two-phase system has been used to fractionate membrane fragments obtained by press treatment of Class II chloroplasts. By the counter-current distribution technique membrane particles are separated according to their surface properties such as charge and hydrophobicity. The fractions obtained were analysed with respect to photochemical activities, chlorophyll and P-700 contents. The Photosystem II enrichment after counter-current distribution was better than that obtained by differential centrifugation of the disrupted chloroplasts. However, the best separation of Photosystem I and II enriched particles could be achieved if differential centrifugation was combined with the counter-current distribution technique. Each centrifugal fraction could be further separated into Photosystems I and II enriched fractions since the Photosystem II particles preferred the dextran-rich bottom phase while the Photosystem I particles preferred the polyethylene glycol-rich top phase. By this procedure it was possible, without the use of detergents, to obtain vesicles which were more enriched in Photosystem II as compared to intact grana stacks. The partition behaviour of undisrupted Class II chloroplasts and the Photosystem I centrifugal fraction was the same. This similarity indicated that the membrane which is exposed to the surrounding polymers by the Class II chloroplasts is the Photosystem I rich membrane of the stroma lamellae.

2,6-Dichloroindophenol↗
PubMed1976

IgM complex receptors on subpopulations of murine lymphocytes.

Murine lymphocytes from spleen, lymph node, and thymus were examined for IgM complex receptors. Lymphocytes from all three organs were found to bind SRBC sensitized with IgM from various sources including: primary anti-SRBC serum, murine and rabbit anti-Escherichia coli LPS sera, and a murine IgM myeloma (MOPC 104E). Rosette formation by lymphocytes with IgM-sensitized SRBC was inhibited by soluble antigen-IgM complexes but not by IgM or antigen alone. Rosette formation was also inhibited by human IgM (Fc)5mu but not by Fab mu. Antiserum and complement treatment of the cells and subsequent recovery of the viable cells by trypsinization, filtration, and washing revealed the IgM rosette-forming cell (RFC) in the thymus to be a T cell. Spleen on the other hand was found to contain both B and T cells capable of binding IgM sensitized SRBC. Removal of both B and T cells from spleen cell suspensions eliminated all IgM RFC. The IgM complex receptor was found to be trypsin insensitive. Anti-Ig column fractionation enriched IgM RFC in spleen and lymph node suspensions passed through the columns, whereas cells bearing surface Ig, IgG complex receptors, and C3 receptors were retained in the columns.

Animals↗
PubMed1975

Perturbations in fluid balance induced by medially placed forebrain lesions.

Acute and chronic effects on the fluid balance of radio-frequency forebrain lesions were studied in the goat. Medial lesions which involved practically the entire anterior wall of the third cerebral ventricle cause persistent loss of thirst and lack of significant antidiuretic hormone (ADH) release in response to hypernatraemia and plasma hyperosmolality. As acute response to such lesions an uncompensated, temporary water diuresis was seen, which rapidly caused pronounced hypernatraemia and hypovolaemia. Lesions extending laterally to encroach upon the supraoptic nuclei resulted in persistent signs of weak, inappropriate ADH secretion (=impaired water diuresis, renal salt wasting, and pronounced hyponatraemia during hydration). Forebrain damage, mainly restricted to the septal region, caused hyperdipsia. In some goats, obvious post-lesioning increase in salt appetite was observed which could not be coreelated to the extent of their forebrain damage. The results are discussed in relation to hypothalamic syndromes in man and previous studies on central control of fluid balance in the goat.

Animals↗
PubMed1975

Duration of central action of angiotensin II estimated by its interaction with csf Na+.

In pre-hydrated goats, an urge to drink persisted for approximately half an hour after combined infusions of angiotensin II and hypertonic (0.5 M) NaCl into the lateral or third cerebral ventricle. The intraventricular infusion of angiotensin/glucose solution, having no dipsogenic action of its own, markedly accentuated the dipsogenic and antidiuretic effects of the subsequent intraventricular infusion of hypertonic NaCl. The possibility is discussed that angiotensin may be bound at periventricular receptor sites where it continues to interact with Na+ in eliciting thirst and ADH release for about half an hour.

Angiotensin II↗
PubMed1975

Recovery of ADH activity in the urine of goats under normal and stimulated conditions.

The hydrated goat was used for bioassays of antidiuretic hormone (ADH) activity recovered by resin column separation from the urine of other animals of the same species. A methodological innovation in the separation procedure was ethanol purification of the column before elution. In this manner substances which sometimes obscured the bioassays were eliminated without loss of ADH activity. With the bioassay method employed, it was possible to determine to the nearest 0.5 of a mU the ADH activity of unknown samples, provided they contained between 0-5 mU of ADH. When arginine vasopressin was infused intravenously into hydrated animals, slightly more than 10% of its antidiuretic activity was recovered in the urine. In the water replete goat the ADH activity found in the urine was of the order of 1 mU per hr urine secretion, indicating a neurohypophyseal ADH release of approximately 5 muU/kg min. After 48 h of dehydration in an environmental temperature of 20 degrees C the renal ADH excretion increased to about 8 mU/h, suggesting an 8-fold increase of ADH secretion over basic, water replete secretion of ADH. ADH secretion of the same high order was induced in hydrated animals by the infusion of angiotensin II together with hypertonic NaCl into the lateral cerebral ventricle.

Angiotensin II↗
PubMed1975

Varicose ulcers.

The results of a combined dermatological and surgical treatment of varicose ulcers was studied in 100 patients. This chronic disease, often persisting for decades, was halted in 90 percent of leg operated upon. Even when the general outcome of the treatment was favourable, it was found that, for 5 out of the 12 ulcers which were the same or larger in size at follow-up than before operation, the patient assessed the result as good or even excellent. This finding deserves further study. It indicates that patients and physicians sometimes use different standards by which to measure therapeutic success.

Aged↗
PubMed1975

IgM antibody-dependent cell-mediated cytotoxicity in the Moloney sarcoma virus system: the involvement of T and B lymphocytes as effector cells.

Antibody-dependent cell-mediated cytotoxicity in the Moloney sarcoma virus (MSV) system was analyzed with respect to the subpopulations of effector cells involved in tumor target cell destruction when IgM was used as the sensitizing antibody. With unfractionated sera from animals that had undergone regression primary MSV tumors it was found that macrophages did not contribute to the cytotoxicity induced by normal spleen cells that were syngeneic to the target cells. The IgM fraction of MSV regressor sera was found to induce cytotoxicity against the target cells by immunoadsorbent column-fractionated normal spleen cells, which were either depleted of T cells or B cells, according to the specificity of the columns. Immune IgM was also found to potentiate the activity of MSV regressor spleen cells that had been similarly fractionated. Furthermore, IgM antibody was found to induced cytotoxicity by normal spleen cells which had been depleted of either T or B cells by the appropriate antiserum (anti-T or anti-Ig) in the presence of complement and subsequent recovery of the viable cells by trysinization, filtration, and washing. However, spleen cells treated with both anti-T and anti-Ig sera simultaneously in the presence of complement and subsequet recovery of viable cells, were not induced to be cytotoxic against the IgM-coated tumor target cells. Further support oy T cells was provided by an experiment showing the induction with IgM of cytotoxicity against the target cells by normal thymocytes.

Animals↗
PubMed1975

Antibody-dependent lymphocyte cytotoxicity in the murine sarcoma virus system: activity of IgM and IgG with specificity for MLV determined antigen(s).

Antisera with specificity for Moloney leukemia virus-(MLV) determined antigen(s) were studied for their ability to induce MLV antigen bearing target cell reduction by lymphocytes in microcytotoxicity assays. Sera from animals which had regressed Moloney sarcoma virus (MSV) tumors as well as sera from animals with progressively growing MSV tumors were found to induce normal lymphocytes to be active against the targets. Regressor serum was found also to induce cytotoxicity by immune lymphocytes from a tumor-bearing animal 15 days after MSV and from a regressor 50 days after MSV infection. Both the 19S and 7S Sephadex G-200 fractions of the antisera were found to induce cytotoxicity by normal lymphocytes and to potentiate the cytotoxicity of MSV immune lymphocytes. These activities were shown to be IgM and IgG, respectively, by the use of Sepharose-coupled anti-mouse IgM and anti-mouse IgG columns. All activity was removed by passing sera over both columns.

Absorption↗