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Biomedical subjects

R Hultborn

Publications and source records attributed to R Hultborn.

At least 37 records · Page 2Linked to original sources
PubMed1986

Vascular reactivity to norepinephrine of 7,12-dimethylbenz(a)anthracene-induced rat mammary tumors and normal tissue as studied in vitro.

Vascular reactivity to norepinephrine has been studied in dimethyl-benz(a)anthracene-induced rat mammary neoplasia and compared with that of skeletal muscle, salivary gland, kidney, and uterus by means of an artificial perfusion technique. Perfusion of tissues and organs was measured with the microsphere tracer technique during smooth muscle relaxation and infusion of norepinephrine at two different dose levels. This procedure makes possible a dose-response analysis of several tissues under controlled conditions without confounding endogenous vasoregulation. The tumor vascular bed has a low perfusion capacity during smooth muscle relaxation and responds rapidly with an increased resistance to norepinephrine infusion. The results indicate a hypersensitivity, although the relative maximal constrictor response is equal to or less than that of other vascular beds studied.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1985

Effects of noradrenaline on interstitial fluid pressure in induced rat mammary tumours.

Interstitial fluid pressure was measured by the wick-in-needle technique in DMBA-induced rat mammary tumours during resting conditions and during noradrenaline infusion. The rate of infusion was chosen to increase the systemic blood pressure by 30-40 mmHg, known to result in a markedly increased vascular resistance of these tumours. During resting conditions tumour interstitial fluid pressure was 10.3 +/- 1.3 mmHg (n = 13) but fell to 7.0 +/- 1.1 mmHg (n = 13) during noradrenaline infusion. The results suggests that noradrenaline is likely to affect the pre-capillary resistance vessels of the tumour vascular bed. This result, together with earlier perfusion studies, indicates that noradrenaline is unsuitable for increasing tumour cell perfusion as an adjunctive in radiation and cytotoxic drug therapy.

Animals↗
PubMed1985

A spectrophotometric method for measuring oxygen consumption in monolayers of cultured endothelial cells.

A new method for measuring oxygen consumption in monolayer cell cultures is described. Cells are cultured in shallow microchambers etched in glass chips. A haemoglobin solution is added and the microchambers are sealed airtight, the oxygenated haemoglobin solution serving as an indicator of oxygen tension within the microchamber as well as a source of oxygen. With cellular extraction of oxygen, an increasing amount of reduced haemoglobin is formed within the microchamber resulting in an increased absorbance of the haemoglobin solution at 435 nm. With a specially prepared device, it is possible to record this absorbance change with an ordinary laboratory spectrophotometer and, from this recording, it is possible to calculate the respiratory rate, provided the number of cells (or any other quantity of biological material), microchamber volume and haemoglobin concentration are known. Repeated measurements on the same undisturbed culture is possible. The system was tested on monolayer cultures of endothelial cells from the rat pulmonary artery.

Animals↗
PubMed1985

Vascular resistance characteristics of 7,12-dimethylbenz(a)anthracene-induced rat mammary tumors and normal tissues as studied in vitro.

Vascular perfusion characteristics have been studied in dimethylbenz(a)anthracene-induced rat mammary neoplasia and compared with those of skin, skeletal muscle, salivary gland, kidney, spleen, uterus, and brain by means of an artificial perfusion technique. Perfusion of tissues and organs was measured by the microsphere tracer technique. This procedure makes possible a detailed hemodynamic analysis of several tissues under controlled conditions, in this study maximum vascular relaxation, without confounding endogenous vasoregulation. The maximal perfusion capacity, i.e., during smooth muscle relaxation, of tumors and various tissues was related to perfusion pressure at three levels by means of three differently labeled microspheres. Tumors, especially large ones, have a low maximum perfusion capacity, i.e., high vascular resistance, compared to most other tissues. For the tumors, a relatively high perfusion pressure is required to open up the otherwise collapsed vascular network.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Blood flow and reactivity to noradrenaline in induced and autotransplanted DMBA rat mammary neoplasia.

Blood flow during the 'resting condition' and during noradrenaline infusion was compared by means of a microsphere tracer technique in induced DMBA-tumours along the mammary ridge and in autotransplanted tumours, as well as in abdominal skin, skeletal muscle, liver and kidneys. During 'resting conditions' the blood flow of tumours transplanted into skeletal muscle of the hindlimb, liver and kidney was similar to that of the non-transplanted tumours present along the mammary ridges. A pronounced decrease of blood flow upon moderate noradrenaline infusion was characteristic of autotransplanted as well as non-transplanted tumours, which contrasted to the insignificant reaction of skeletal muscle. The striking similarities in blood flow and reactivity of non-transplanted DMBA tumours and autotransplanted ones, and the dissimilarities of the transplanted tumours and the hosting tissues, favour the idea that these tumours regulate their blood supply irrespective of host tissue.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Transcapillary passage of albumin in mammary tumours and in normal lactating mammary glands of the rat.

A triple-isotope technique was used to obtain albumin clearances and blood flow in DMBA induced mammary tumours, normal lactating mammary glands and various other tissues of the rat. Albumin clearance was high both in tumours (0.0337 ml/min/100 g) and in lactating mammary glands (0.0414 ml/min/100 g). Albumin extraction (defined as the ratio of clearance over plasma flow) was exceptionally high in tumours (23 X 10(-4)) and lactating glands (18 X 10(-4)) as compared to all other tissues (1-7 X 10(-4)). This probably reflects an increased capillary permeability to macromolecules and/or a change in the relation between blood flow and available capillary surface area, both in the physiological, hormonally induced gland and in the abnormal neoplasia derived from the same tissue. Increased extravasation of albumin, together with other changes (e.g. impaired lymph formation) may be important factors behind the production of increased tumour interstitial pressure, which tend to reduce nutritional blood flow in tumours.

Albumins↗
PubMed1983

Hypothermic perfusion of human kidney carcinoma: effects on viability and perfusate distribution.

A more deteriorating effect on tumour tissue than on normal renal parenchyma by hypothermic perfusion has previously been observed. The purpose of this study was to further evaluate changes in the perfusate distribution and the viability of normal cortical tissue and of kidney carcinoma during hypothermic perfusion. Tumour-involved kidneys obtained by nephrectomy from 12 patients were studied either with regard to viability, as measured with the Na+-K+ pump function in incubated tissue slices, or with regard to perfusate flow, as analysed with an isotope labelled microsphere technique. Six days of hypothermic perfusion decreased the potassium content in the tumour tissue, while it was mainly unchanged in the cortical tissue. The steady-state level of potassium in incubated slices reflected that the transmembrane K+ influx was unchanged after 6 days of perfusion in normal cortical tissue, whereas a significant reduction was observed in the tumour tissue. The relative perfusate flow in the tumour, when compared to the normal kidney cortex flow, was reduced from 60% after 1 hr of perfusion to 30% after 6 days of perfusion.

Adult↗
PubMed1983

Vascular reactivity and perfusion characteristics in 7,12-dimethylbenz(a)anthracene-induced rat mammary neoplasia.

Blood flow during "resting conditions" and during noradrenaline infusion were studied by the labeled microsphere technique in dimethylbenz(a)anthracene-induced mammary tumors, skin, muscle, and lung in the rat. Intratumoral distribution of flow was studied by autoradiography of spheres trapped in the vascular beds of the tumors. Histological examination was performed and correlated to the blood flow data. Mean blood flow to the tumors during "resting conditions" was relatively high (49 ml/min/100 g tissue) but was substantially decreased (5 ml/min/100 g tissue) during noradrenaline infusion which produced a pressure elevation of 35 mm Hg. Thus, vascular resistance of the tumor tissue increased dramatically. Cardiac output increased, but total systemic resistance was unchanged. Vascular resistance in muscle was unchanged in contrast to an increase seen in skin. Shunted systemic blood flow to the lungs and bronchial arterial flow decreased indicating reactivity of abnormally large arteriovenous passages in the tumors. Poorly differentiated tumors had a higher vascular resistance than did well-differentiated tumors. Autoradiography revealed a nodular flow distribution with a slight tendency of higher perfusion in the periphery of these tumors.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1982

Respiration rate in human pituitary tumor explants.

Studies on the respiration rate of human pituitary tumor tissue have so far been lacking in the literature. This study presents the results from four adenomas causing acromegaly, all with different clinical degrees of the disease. Determination of oxygen uptake was performed in vitro with a spectrophotorespirometric system. Pieces of the tumors were explanted to an organ culture system with a high degree of stability. The secretion rate of growth hormone (GH) and prolactin (PRL) was determined. After 4-8 days in vitro, specimens were analyzed for respiration rate. This was approximately 1-1.5 microliters O2/h/micrograms dry weight. The activity of the pituitary tumor tissue was characterized by both the hormone secretion rate and the respiration rate. Particularly active foci were found to occur in the adenoma tissue. Depending on the individual tumor, the GH secretion rate was approximately 0.1-100 pmol/micrograms dry weight/h and PRL secretion rate approximately 0.4-18 micrograms/micrograms dry weight/h. The respiration rate--as is also the hormone secretion rate--is dependent on the time in vitro prior to analysis. The respiration rate in individual tumors is a parameter which does not reflect GH or PRL serum levels or clinical activity of the disease.

Acromegaly↗
PubMed1982

Interstitial fluid pressure in DMBA-induced rat mammary tumours.

Interstitial fluid pressure (IFP) in DMBA-induced rat mammary tumours was measured by micropuncture with sharpened glass capillaries (diameter 1-3 micron) and by the 'wick-in-needle' technique (WIN). IFP in the superficial layers of the tumours (depth less than 800 micron) was measured with micropuncture, while WIN was used for measurements in deeper areas. IFP in the superficial layers of the tumours was 2.4 mmHg (SD 2.4, n=19), while IFP in deeper layers increased with increasing tumour weight. Thus central IFP in tumours weighing more than 5.5 g was 16.0 mmHg (SD 4.8, n=10), with a maximum value of 23.3 mmHg. When related to tumour histopathology a significant correlation was found between high cellular differentiation (i.e. low degree of malignancy) and high interstitial fluid pressure only. The high IFP may be secondary to a high capillary protein premeability and/or a relatively insufficient lymphatic drainage. A further rise in IFP might result from ischaemic cell swelling and/or a continuous cell proliferation within a tissue of rather low compliance. Together or alone one or more of these factors could facilitate the development of a compartment syndrome with concomitant cell death and tissue necrosis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1981

[Metabolic and circulatory aspects of hypothermic perfusion of human kidney cancers].

In this study a report is made on the hypothermal perfusion of 15 renal tumours. Protein synthesis by incorporation of 14C leucine, lipide synthesis by conversion of 14C mevalonic acid and the activity of the sodium-potassium pump by incubation of sections of tissue were used as parameters of the vitality of the tissue. Circulation was studied before and after perfusion by means of angiography and the microsphere technique. After 6 days of perfusion the tumour tissue is found to be less vital in comparison with the renal cortex.

Cold Temperature↗
PubMed1980

Blood flow and reactivity to noradrenaline in DMBA-induced rat mammary neoplasia.

Blood flow during "resting condition' and during noradrenaline infusion were studied by microsphere tracer technique in DMBA-induced mammary tumors, hindpaw, muscle and liver in rats. During "resting condition' the mean tumor blood flow was relatively high and in the same range as that of the hindpaw representing mainly skinflow, but during noradrenaline infusion there was a marked decrease in tumor blood flow as was the case for hindpaw, while cardiac output, muscle flow and arterial liver flow remained essentially unaltered. There was an inverse relation between tumor size and blood flow.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1977

A simple system for inspection of microelectrophoretic patterns.

An inexpensive device for inspection of electrophoretic patterns on microgels is described. A common slide frame is modified in order to hold inside microgels immersed in liquid, so that the gels may then be projected on paper screens. The electrophoretic patterns may be drawn on the basis of the gel images. Staff-meeting presentation of microelectrophoretic patterns seems to be another application of the system.

Animals↗
PubMed1976

Effect of luteinizing hormone on respiration of the preovulatory cumulus oophorus of the rat.

The effect of luteinizing hormone (LH) on the respiration of isolated cumulus cell complexes (the oocyte surrounded by cumulus granulosa cells) obtained from immature Sprague-Dawley rats injected with 10 IU pregnant mare's serum gonadotropin on day 30 was investigated. The cell complexes were isolated from preovulatory follicles of rats killed at specific time intervals on the day preceding ovulation, i.e., on day 32. The samples were incubated in Eagle's tissue culture medium. Oxygen uptake was recorded either with the Cartesian diver technique or with a recently described microspectrophotometric technique using hemoglobin as an indicator. Exposure to exogenous bovine LH in vitro or in vivo or to endogenous LH, i.e., the preovulatory LH-surge, resulted in a marked decrease in respiratory activity of the cumulus cell complex, as revealed by both techniques. The cumuli exposed to LH showed an oxygen uptake of approximately 40-65% of the control cumuli. The results suggest that LH has a direct effect on this cell complex resulting in a decreased oxidative metabolism.

Animals↗