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Biomedical subjects

O Braendstrup

Publications and source records attributed to O Braendstrup.

At least 37 records · Page 2Linked to original sources
PubMed1983

Necrotizing vasculitis in athymic rats with infarct kidney hypertension.

Infarct kidney hypertension was induced in congenital athymic nude rats and in their haired normal littermates. In both groups a significant and similar elevation of blood pressure was observed. The mesenteric vessels were studied histologically five, 12 and 20 days after operation. Necrotizing vasculitis with and without perivascular inflammatory reactions was found in mesenteric arteries and arterioles in six out of six athymic and in six out of 11 control rats. In sham operated athymic rats and in haired littermates neither hypertension nor vasculitis was observed. These observations indicate that the thymus play no role in the pathogenesis of acute hypertensive vascular disease.

Animals↗
PubMed1983

Effect of diazoxide-induced hypotension on cerebral blood flow in hypertensive rats.

The effect on cerebral blood flow of acute diazoxide-induced hypotension was studied in rats with renal and spontaneous hypertension. Diazoxide (5 mg/kg, i.v. bolus), caused arterial pressure to fall rapidly to that of normotensive rats, i.e. c. 75 mmHg. There was a concomitant fall in cerebral blood flow of about 35% (P less than 0.01) in renal hypertensive rats and 25% (P less than 0.05) in spontaneously hypertensive rats; the greater fall in flow in the former corresponded to a greater drop in pressure. Flow remained at these reduced levels during a 2 h observation period. Histological examination revealed small areas of ischaemic damage in the brains of five of the twelve animals. In control hypertensive rats not given diazoxide, cerebral blood flow and blood pressure were stable during a 2 1/2 h period and there was no evidence of ischaemic damage to the brains. The diazoxide-induced reduction in cerebral blood flow was interpreted as being secondary to a blood pressure fall to below the lower limit of cerebral blood flow autoregulation. No evidence was found of direct effects on the cerebral circulation such as seen with ganglionic blockers, alpha-blockers and cerebral vasodilators.

Animals↗
PubMed1983

Infarct-kidney hypertension in the rat mutant nude.

Infarct-kidney hypertension was induced in congenital athymic nude rats, and in their immunologically normal haired littermates. In both groups a significant initial increase in blood pressure was seen in the course of the first 30 days. In the remainder of the observation period of 120 days the mean blood pressure in the nude rats decreased to a significantly lower level where-as in the haired rats the mean blood pressure remained unchanged at the high level. Although a high mortality weakened the results, it is hypothesized that the failing ability to maintain the elevated blood pressure into the late phase in the nude rats could be due to impaired thymus function. Nine of 14 haired rats had increased numbers of lymphocytes around intrarenal arteries, in contrast to only 1 of 10 nude rats. A periarteritis nodosa like picture was observed around mesenterial arteries of 3 nude and 2 haired rats. The level of plasma renin was similar preoperatively in nude and haired rats. Infarction of the kidney was followed by a significant decrease in the plasma renin level in both nude and haired rats, which at 10 days was significantly lower in haired than in nude rats, despite a higher blood pressure in the latter.

Animals↗
PubMed1982

Cerebral blood flow in rats with renal and spontaneous hypertension: resetting of the lower limit of autoregulation.

The effect of chronic hypertension on cerebral blood flow (CBF) was studied in anaesthetised rats. CBF was measured with the intracarotid 133Xe injection method. Rats with spontaneous and renal hypertension were compared with normotensive controls. The lower limit of autoregulation was determined during controlled haemorrhage. In the normotensive rats, CBF remained constant until mean arterial pressure (MAP) had decreased to the range of 50-69 mm Hg. Thereafter, CBF decreased with each further decrease in MAP. In both types of hypertensive rats, CBF remained constant until MAP had decreased to the range of 70-89 mm Hg. Thus, a 20-mm Hg shift of the lower limit of CBF autoregulation was found in both spontaneous and renal hypertensive rats. A neuropathological study revealed ischaemic brains lesions in half of the hypertensive rats following hypotension, whereas only a single lesion was found in one of six normotensive rats. No ischaemic brain lesions were found in a control study in which CBF was shown to be stable over a 21/2-h period. In conclusion, hypertensive rats showed a shift of the lower limit of CBF autoregulation as well as an increased susceptibility to ischaemic brain damage during hypotension. These findings presumably reflect hypertensive structural changes in the cerebral circulation.

Animals↗
PubMed1981

Malignant non-Hodgkin lymphoma of the gastrointestinal tract. A histopathological review of 34 cases.

Thirty-four cases of malignant non-Hodgkin lymphomas of gastro-intestinal origin were histopathologically reviewed employing Rapaport's (18) classification. The majority of the tumours, 25, were localized to the stomach. The rest of the lesions occurred with decreasing frequency throughout the gastro-intestinal tract, with the exception of 3 rectal cases. Thirty lymphomas displayed a purely diffuse pattern, 1 was purely nodular, and 3 were nodular with diffuse components. "Histiocytic" lymphoma was the commonest type, including 16 cases; poorly differentiated lymphocytic type next, with 10 cases. The histopathology of this series does not differ from those of comparable studies.

Adolescent↗
PubMed1979

Macrophage-lymphocyte clusters in the immune response to soluble protein antigen in vitro. VIII. Cinephotomicrographic studies.

T cells from immune guinea-pigs produce clusters in vitro with macrophages pulsed with soluble protein antigens. The formation of clusters is antigen-specific. Time-lapse cinephotomicrography was used to study the sequence of events leading to cluster formation and the kinetics of already formed clusters. The central lymphocyte attaches through a broad base to the macrophage during the first few hours of incubation. After several hours, during which the central lymphocyte is situated alone on the surface of the macrophage, free lymphocytes begin to interact for shorter or longer periods of time through their uropods with the central lymphocyte, thus acting as peripheral lymphocytes. In spite of a frequent traffic of peripheral lymphocytes in and out, the cluster is a relatively stable structure. Occasionally the entire complex of lymphocytes leaves the macrophage, moves randomly in the culutre and attaches to a new macrophage or returns to the same macrophage.

Animals↗
PubMed1979

Macrophage-lymphocyte clusters in the immune response to soluble protein antigen in vitro. IX. Antigen-pulsed macrophages as a tool for specific absorption of cluster-initiating T cells.

T-cell populations from guinea-pigs sensitized to the protein antigens purified protein derivative of Mycobacterium tuberculosis, ovalbumin, or horseradish perioxidase can be selectively depleted of cells capable of initiating antigen-specific macrophage-lymphocyte clusters in vitro. The depletion is achieved by incubating the T cells on a monolayer of antigen-pulsed macrophages in a Petri dish for some hours and then gently aspirating the cells not adhering to the bottom of the dish. When subsequently assayed, the aspirated cells were found to be depleted of cluster-initiating lymphocytes committed to horseradish peroxidase, monolayers of macrophages pulsed with that antigen must be used. The optimum time for incubation on the absorbing monolayer appears to be 4 h, and two successive incubations are more effective than one. The cell density of the absorbing monolayer and the handling of the Petri dish may be critical for effective removal of the cluster-initating lymphocytes. With optimum procedure we have achieved up to 90% depletion of specific cells with no depletion of cells committed to a control antigen.

Absorption↗
PubMed1979

Macrophage-lymphocyte clusters in the immune response to soluble protein antigen in vitro. VII. Genetically restricted and nonrestricted physical interactions.

We have assessed the genetic restrictions on physical interactions between macrophages and central lymphocytes and between central and peripheral lymphocytes in antigen-specific macrophage-lymphocyte clusters with respect to I-region differences of inbred strains 2 and 13 guinea pigs. When using lymphocytes from guinea pigs immunized with DNP-OVA or DNP-GL in CFA, the antigen-specific interaction between central lymphocyte and macrophage requires that both cells be derived from animals syngeneic at the I-region of the major histocompatibility complex. In studies using antigens, the responses to which is under the control of MHC-linked Ir genes, macrophages from the responder, but not from the nonresponder parental strain support cluster formation with responder x nonresponder F1(2 X 13) T cells. In contrast, the physical interactions between central and peripheral T lymphocytes are not restricted by the I-region of the MHC and the peripheral lymphocyte need not be from an animal immune to the antigen used to drive macrophage central lymphocyte interactions.

Animals↗
PubMed1979

Specific absorption of T lymphocytes committed to soluble protein antigens by incubation on antigen-pulsed macrophage monolayers.

Monolayers of macrophages (Mphi) pulsed with antigen were used as immunosorbents for T lymphocytes from guinea pigs primed to soluble protein antigens. T lymphocytes were cultured on the Mphi monolayers for 4 hr, then aspirated and reincubated on a fresh monolayer pulsed with the same antigen for a second and a third step. T lymphocytes so treated were selectively deprived of cells responding in assay for antigen-dependent proliferation against the antigen used for pulsing the absorbing monolayer, but maintained their response to other antigens. The lymphocytes adhering to the Mphi of the absorbing monolayer were capable of giving a full response to the antigen used for pulsing the Mphi of the monolyers. The proliferative response of F1 T lymphocytes to antigen in association with Mphi of either parental strain could be absorbed leaving the response to antigen in association with Mphi of the other parental strain. The absorption of the proliferative response was not inhibited by addition of excess soluble antigen to the medium of the absorption culture. Our results indicate that specific guinea pig T lymphocytes responding by proliferation to soluble protein antigens recognize and bind specifically to a complex of Ia antigen and protein antigen at the surface of the Mphi.

Absorption↗
PubMed1974

Macrophage-lymphocyte clusters in the immune response to soluble protein antigen in vitro.

We have studied the physical interaction between macrophages and lymphocytes during the immune response to purified protein derivative of tuberculin (PPD) in vitro. Mixtures of peritoneal macrophages and lymph node lymphocytes from guinea pigs immunized with tubercle bacilli formed cell clusters during 20 h of culture with PPD. The number of clusters produced was correlated to the number of immune lymphocytes in the cultures. Peritoneal macrophages which had been pulsed with PPD and untreated lymph node lymphocytes produced cell clusters in the absence of free PPD in numbers equivalent to those produced by the same cells in the presence of free PPD. In cultures containing a mixture of PPD-pulsed macrophages, not-pulsed macrophages, and immune lymphocytes with no free PPD, cell clusters developed mainly between the antigen-pulsed macrophages and lymphocytes. Cluster formation was antigen-specific with the specificity residing in the lymphocytes, mainly or exclusively in the T lymphocytes. These data indicate that in the process of cell cluster formation macrophages serve as antigen-binding (or -processing) cells, while a subpopulation of lymphocytes interact physically and specifically with the macrophages.

Animals↗