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Biomedical subjects

L Jansson

Publications and source records attributed to L Jansson.

At least 145 records · Page 8Linked to original sources
PubMed1994

Inhibition of nitric oxide synthase by NG-nitro-L-arginine causes a preferential decrease in pancreatic islet blood flow in normal rats and spontaneously diabetic GK rats.

To elucidate the effect of nitric oxide (NO) on the blood flow of the pancreatic islets, the NO synthase inhibitor NG-nitro-L-arginine (N-arg; 25 mg/kg BW) was administered iv to rats 10 min before pancreatic blood flow was measured with a nonradioactive microsphere technique. In male Sprague-Dawley rats, N-arg induced a marked decrease in islet blood flow (16 +/- 4 vs. 44 +/- 8 microliters/min.g pancreas; P < 0.001) and a less pronounced decrease in whole pancreatic blood flow (0.27 +/- 0.04 vs. 0.43 +/- 0.06 ml/min.g; P < 0.05), leading to a markedly decreased fractional islet blood flow (5.5 +/- 0.9% vs. 10.3 +/- 1.3%; P < 0.02). In a second experiment, injection of D-glucose (300 mg/kg BW, iv) in male Sprague-Dawley rats induced a selective increase in islet blood flow (P < 0.05). Such an increase has previously been shown to be mediated by a vagal cholinergic mechanism. Administration of N-arg to these rats resulted in decreased pancreatic (P < 0.05), islet (P < 0.001), and fractional (P < 0.001) islet blood flow, which did not differ from those observed in normoglycemic rats after treatment with N-arg. Furthermore, we studied the mechanism behind the previously described increase in islet blood perfusion, mediated by the vagus nerve, in F1-hybrids of the GK (Goto-Kakizaki) rat, a spontaneous animal model of noninsulin-dependent diabetes mellitus. Administration of N-arg to female GK rats resulted in decreases in islet (P < 0.001), pancreatic (P < 0.01), and fractional islet blood flow (P < 0.001) to the levels observed in female Wistar rats treated in parallel. These data are consistent with the possibility that NO is an important physiological regulator of islet blood flow. Furthermore, the vagally dependent high levels of islet blood flow demonstrated in the GK rat appear to be mediated by a mechanism involving NO.

Amino Acid Oxidoreductases↗
PubMed1994

Pancreatic and islet blood flow in F1-hybrids of the non-insulin-dependent diabetic GK-Wistar rat.

Previous studies have indicated that various conditions under which an increased functional load is posed on the pancreatic islets, e.g. partial pancreatectomy and continuous glucose infusions, may influence the microcirculation of the pancreas. To investigate further the effects of elevated functional demand on the islets, the blood perfusion of the whole pancreas and the pancreatic islets was measured with a microsphere technique in an animal model presenting impaired glucose tolerance and mild hyperglycemia, namely F1-hybrids of the spontaneously non-insulin-dependent diabetic GK-Wistar rat. Normal Wistar rats served as controls. All hybrids had a pathological intraperitoneal glucose tolerance test 1 week before the blood flow measurements, which were performed in 10-12-week-old rats. Both the whole pancreatic and the islet blood flows were increased in the hybrids compared to controls. The fractional islet blood flow, i.e. the fraction of whole pancreatic blood flow diverted through the islets, also was increased in the hybrid rats (12.6 +/- 0.6% vs 9.8 +/- 0.5% in controls, p < 0.01). A bilateral abdominal vagotomy performed 30 min before the blood flow measurement markedly decreased the blood flow values of the islets and the whole pancreas in both groups of rats. After vagotomy, the islet blood flow in the hybrid rats was similar to that of the vagotomized control animals (8.2 +/- 0.8 and 7.5 +/- 1.4%, respectively). It is concluded that the increased pancreatic and islet blood perfusion observed in F1-hybrids of the GK-Wistar rat depends on a mechanism mediated by the vagus nerve.

Animals↗
PubMed1994

Pancreatic islet blood flow in the rat after administration of islet amyloid polypeptide or calcitonin gene-related peptide.

Anesthetized male Sprague-Dawley rats (350-400 g) were injected intravenously with either 0.1, 1, 15, or 25 nmol rat islet amyloid polypeptide (IAPP), 65 or 650 pmol rat calcitonin gene-related peptide (CGRP), or saline alone. IAPP at the two highest doses decreased the mean arterial blood pressure (BP), increased blood glucose concentrations, and decreased serum insulin concentrations. CGRP at both doses decreased the BP but did not affect the blood glucose concentrations. The blood flow to the whole pancreas, pancreatic islets, adrenal glands, colon, duodenum, liver, and kidney was measured with a microsphere technique 30 min after administration of IAPP and 3 min after injection of CGRP. The two higher doses of IAPP (15 and 25 nmol) markedly reduced the whole pancreatic blood flow, whereas the islet blood flow remained unaffected. This resulted in an increase in the fraction of whole pancreatic blood flow diverted through the islets from approximately 10 to 17%. No blood flow changes in the pancreas or the islets were observed when 0.1 or 1 nmol IAPP was injected. CGRP at both doses caused a decrease in both whole pancreatic and islet blood flow. No changes in fractional islet blood flow were observed, despite similar effects on mean arterial BP as observed after IAPP injections. Neither adrenal, duodenal, colonic, hepatic, skeletal muscle, nor renal blood flow were significantly affected by any of the concentrations of IAPP used, whereas 650 pmol CGRP decreased both duodenal and colonic blood flow. We conclude that IAPP and CGRP have different effects on pancreatic islet blood flow and that IAPP may be of importance for islet blood flow regulation.

Amyloid↗
PubMed1994

Washout kinetics of blood cells from the perfused pancreas of normoglycemic and diabetic rats.

The aim of the present study was to evaluate vascular compartments within the rat pancreas with compartmental analysis of the outflow of blood cells from the perfused gland in situ. The presence of two vascular compartments requiring approximately 15 and 30 min for emptying, was noted in normoglycemic rats. The pancreas from diabetic rats, in which the islet beta-cells had been destroyed by intravenous injection of streptozotocin 1 or 6 weeks earlier, demonstrated the same outflow characteristics. It is therefore likely that these observations reflect the presence of two vascular compartments within the rat pancreas, possibly representing the islet-acinar vasculature and the ductal vasculature.

Animals↗
PubMed1994

Quality of periodontal healing. III: Periodontal width following long epithelial junction or reparative cementum formation.

The purpose of the present study was to compare the width of the periodontal space following two different marginal periodontal healing reactions (long epithelial junction and connective tissue healing involving formation of reparative cementum) with the width of normal periodontium, either intact or following reattachment. Twelve permanent lateral incisors in monkeys from a previous experimental study on periodontal wound healing on denuded surfaces were selected based on strict healing criteria. The periodontal width was measured histomorphometrically and compared to the periodontal width on the contra lateral side of the same root where reattachment had taken place and with the width of normal periodontal space of neighbouring untreated teeth. The mean periodontal width for both after formation of a long junctional epithelium and reparative cementum were significantly larger than the control width, approximately 290%. This may be taken as evidence of an impaired functional adaptation of the reparative tissue compared to a reestablished or normal periodontal membrane.

Animals↗
PubMed1994

Retroviral capture of c-erbB proto-oncogene sequences: rapid evolution of distinct viral genomes carrying mutant v-erbB genes with different transforming capacities.

The evolution of oncogene-transducing retroviruses was followed by studying the genomes of five new, erbB carrying retroviruses. These viruses, isolated from cells of one chicken infected with Rous Associated virus 1 (RAV-1), had captured c-erbB sequences as a consequence of RAV-1 integration into the host genome. Their genome structures were distinct; however, their v-erbB genes had sustained identical 5' and 3' deletions and the v-erbB-env junctions were identical at the nucleotide level. The results therefore strongly suggest that all five viruses originate from the same capture event. Sequence analyses of the v-erbB genes from three of these viruses revealed that one of them had undergone no further mutation and lacked detectable capacity to transform cells, therefore probably representing an 'early' form of transducing virus. The two other v-erbB genes contained distinct mutations and differed in their potential to induce fibroblast- and erythroblast transformation; they therefore probably represent later derivatives of the virus that captured the erbB oncogene. The data suggest that the initial retrovirus rapidly underwent many alterations after capture of c-erbB sequences, already in the RAV-1 infected bird as well as during subsequent in vitro isolation procedures. The changes involve both major rearrangements of the genome as well as point mutations that activated the erbB oncogene.

Amino Acid Sequence↗
PubMed1993

Effects of cyclosporin A on the blood flow of the native and transplanted rat pancreas and duodenum.

The aim of the present study was to evaluate the effects of cyclosporin A (CyA) on the blood perfusion of the transplanted pancreas. For this purpose syngeneic pancreaticoduodenal transplantations were performed in Wistar-Furth rats. After nephrectomy the graft was anastomosed using a nonsuturing cuff technique to the left renal vessels. Beginning 7 days after transplantation and then continuing for 2 weeks, CyA (15 mg/kg body weight) or vehicle was given p.o. once daily, 6 days a week. The serum CyA concentrations were greater than 600 ng/ml at all points in time tested. Intraperitoneal glucose tolerance tests were normal in CyA-treated animals after 12 days, but the pancreatic insulin concentration was decreased to the same extent in the native and transplanted pancreas. A microsphere technique was used to measure the blood perfusion of the pancreaticoduodenal graft, the native pancreas and duodenum, and remaining kidney 14 days after starting the CyA treatment. The renal blood flow was markedly decreased by CyA when compared with the control animals. In rats given vehicle alone, pancreatic, islet, and duodenal blood flows were higher in the graft than in the corresponding native organs. However, in rats given CyA, hyperperfusion of the graft was not observed. We conclude that the administration of CyA prevents the transplantation-induced blood flow increase seen in pancreaticoduodenal grafts of vehicle-treated rats. These observations may reflect graft denervation.

Animals↗
PubMed1993

Genes on the X chromosome affect development of collagen-induced arthritis in mice.

Susceptibility to collagen-induced arthritis (CIA) in mice is associated with a class II gene in MHC (Aq) but also with unknown genes outside MHC. Investigated here is the influence of genes on the X chromosome as well as the role of the X-linked immunodeficiency (xid) mutation. Reciprocal male F1 hybrids, bred to be heterozygous or homozygous for Aq, showed a genetic influence in their susceptibility to develop CIA. Crosses were made between B10.G, B10.Q, DBA/1, SWR/J, C3H.Q and CBA/Ca, and all F1 mice were castrated to avoid sex hormone modulation of the susceptibility. A differential timing of arthritis onset and severity were seen in the reciprocal F1 males. An exception was the reciprocal F1 male offspring from SWR/J and DBA/1 crosses which differed only in disease severity late in the course of the disease. The female F1 crosses did not show the same pattern of differential susceptibility to CIA as the F1 males. To exclude the possible influence of the Y chromosome, F1 males of reciprocal crosses were back-crossed to the parental strains creating offspring with equal X chromosomes but divergent Y chromosomes. No difference in development of arthritis was observed in these. The influence of the xid mutation was investigated next. The xid loci from the CBA/N mouse was bred into DBA/1 strain which is highly susceptible to CIA. The resulting congenic DBA/1-xid strain was resistant to induction of CIA and did not develop an antibody response to type II collagen. We conclude that polymorphic genes on the X chromosome modulate susceptibility to CIA. The results from the experiments with mice carrying xid mutations confirm that such immune modulating genes exist on the sex chromosomes.

Animals↗
PubMed1993

Relationship between periapical and periodontal status. A clinical retrospective study.

The purpose of the present investigation was to explore possible relationships between clinical periodontal status in periodontally involved teeth with and without endodontic infection. The investigation was conducted as a retrospective study on a consecutive referral population. The periapical conditions in endodontically-involved single-rooted teeth from a selected patient sample were evaluated and correlated to their periodontal status. There was a significant correlation between periapical pathology and vertical bony destructions. An intra-individual comparison between pocket depth in teeth with and without periapical pathology showed that periapical pathology was significantly correlated to an increased pocket depth in the absence of a vertical bony destruction. It was concluded that an endodontic infection, evident as a periapical radiolucency, promotes periodontal pocket-formation on an instrumented marginal root surface and, consequently, should be regarded as a risk factor in periodontitis progression and be given appropriate consideration in periodontal treatment planning.

Adult↗
PubMed1993

Periodontal healing in teeth with periapical lesions. A clinical retrospective study.

The purpose of the present investigation was to compare clinical periodontal healing in periodontally involved teeth with and without pulpal pathosis. The investigation was conducted as a retrospective study on a consecutive referral population. The periapical conditions in endodontically involved single-rooted teeth from a selected patient sample were evaluated and correlated with their periodontal healing pattern. Multiple regression analysis of the registered variables showed that initial mean pocket depth and time elapsed after treatment significantly influenced change in pocket-depth. Non-surgical treatment of periodontal pockets exceeding 2.5 mm in teeth with horizontal marginal defects, over the observation period, showed significantly reduced mean pocket depth reduction in teeth with periapical pathology compared to teeth without periapical pathology. It was, furthermore, evident that proximal restorations, abutments for fixed bridges and root fillings with and without dowels did not significantly influence pocket depth reduction in the present material. It was concluded, based on the present results, that a root-canal infection, evident as a periapical radiolucency, if left untreated may in the long term perspective result in retarded or impaired periodontal healing following periodontal therapy and, consequently, should be given appropriate consideration when coordinating endodontic therapy and periodontal treatment.

Adult↗
PubMed1993

Differences in the vascular response to terbutaline in the native and transplanted rat pancreas.

Syngeneic pancreaticoduodenal transplantations were performed in Wistar-Furth rats. Fourteen days after implantation, blood perfusion of the whole native and transplanted pancreas, the pancreatic islets and the native and transplanted duodenum was measured with a microsphere technique 5 min after an intravenous injection of 0.5 ml of either saline (n = 6) or terbutaline (1 mg/kg BW; n = 9). Terbutaline decreased the mean arterial blood pressure by approximately 30% (p < 0.001). The substance also decreased the whole pancreatic blood flow of the native pancreas (p < 0.05), but not of the transplanted gland. However, the vascular conductance of the whole pancreas was unchanged after terbutaline administration in both the native and transplanted gland. Islet blood flow (p < 0.001) and islet vascular conductance (p < 0.01) were markedly decreased in the native pancreas. In the transplanted gland, there was, however, no change in islet vascular conductance and only a slight decrease in islet blood flow (p < 0.05). Both the native and transplanted duodenal blood flows were unaffected by terbutaline. One likely explanation for the different effects of terbutaline on the blood perfusion of the native and transplanted pancreas may be that the latter gland is devoid of any physiologically relevant exogenous innervation.

Animals↗
PubMed1993

Reinnervation of transplanted pancreatic islets. A comparison among islets implanted into the kidney, spleen, and liver.

Islets transplanted beneath the kidney capsule become reinnervated during the first 3-4 months after implantation by both afferent and efferent nerve fibers. To evaluate the importance of the implantation organ for this process, the present study compared both the degree and the types of nerve fibers reinnervating islets transplanted into the liver, kidney, and spleen. For this purpose, 150 syngeneic islets were grafted under the kidney capsule of C57BL/6 mice. In addition, the same animals were injected with 150 islets into the spleen or liver. All animals were killed 14 weeks after transplantation, after which the graft-bearing organs were processed for indirect immunofluorescence for neuropeptides and tyrosine hydroxylase (TH), and with acetyl cholinesterase (AchE) staining to visualize nerve fibers. Both afferent (containing substance P and/or calcitonin gene-related peptide) and parasympathetic (containing vasoactive intestinal peptide or AchE) nerve fibers were absent from islets implanted into the spleen; an occasional CGRP fiber was seen in islets implanted into the liver; and all these fibers were regularly seen in islets implanted beneath the renal capsule. The islets implanted into the liver or spleen contained a dense network of sympathetic (containing neuropeptide Y and TH) nerve fibers that was often more dense than in the islet grafts under the kidney capsule. One-fifth of islets implanted into the liver were, however, completely devoid of demonstrable nerve fibers. In conclusion, there are marked differences with regard to the pattern of reinnervation of islets transplanted to different implantation sites.

Acetylcholinesterase↗
PubMed1993

Application of primary nursing within a team setting in the hospice care of cancer patients.

A qualitative study was conducted to obtain a deeper understanding of the hospice care of terminally ill cancer patients, where care was delivered via a primary nursing system combined with a team setting. Relatives of terminally ill cancer patients (n = 20) and the personnel (n = 8) participated in open-ended interviews. Phenomena relating to the philosophy of primary nursing and the hospice movement (continuity; closeness; accountability 24 h/day; individualized care; satisfied physical, psychological, social, and spiritual needs; and support to relatives) were experienced by the relatives, nurses, and physician as "good care." Most of the phenomena defined as important needs by the relatives and personnel were met when the primary nurse was on duty and the team was intact. Needs that were unmet were mainly a result of lack of continuity. Caring for the terminally ill via primary nursing in a team setting was regarded as two-sided by the nurses. It was seen as stimulating and rewarding, as well as demanding and burdensome. Therefore, the need for support to the nurses involved was deeply stressed.

Aged↗
PubMed1993

Experienced and skilled nurses' narratives of situations where caring action made a difference to the patient.

Forty-five skilled and experienced nurses working at long-term, medical and surgical care clinics narrated 88 caring situations. The aim of the study was to interpret these narratives concerning the nurses' caring actions and the type of situations where they experienced that their caring made a difference to the patient. There were eight types of caring actions that were then condensed into three interaction and intervention approaches; 1) deliberate distanced interaction and intervention with the patient; 2) deliberate providing of prerequisites for interaction and intervention with the patient; and 3) deliberate deep interaction with the patient when intervening. These approaches were used when the nurses dealt with the following three types of caring situations: caring focusing on the nurse-patient relationship, on medical intervention, and on practical problem solving. The first two approaches occurred in situations focusing on acute medical intervention and on practical problem solving. All approaches occurred in situations focusing on the nurse-patient relationship. The finding that experienced and skilled nurses described situations where the depth of their contact with the patient varied can be expressed in the phrase "how I act depends on the situation." The skill to find the right level of involvement seems important.

Adult↗
PubMed1993

Experienced nurses' narratives of their being in ethically difficult care situations. The problem to act in accordance with one's ethical reasoning and feelings.

In previous interviews, experienced nurses have reported that their decisions in ethical matters depended "on the situation at hand." We interviewed 18 good, experienced cancer nurses to determine how they handled ethical decisions. They were asked to give an account of difficult situations that required ethical decisions to be made. The 60 narrated situations were interpreted step-by-step departing from the following two questions: What do nurses experience when being in ethically difficult care situations? What does the expression "it depends on the situation at hand how I act" mean? In complex situations, the nurses reported that the ethical situations that arose were regarded either as overwhelming or at the other end of the spectrum, as possible to grasp, and they expressed either loneliness or togetherness, respectively. When reporting overwhelming situations, the nurses mostly referred to themselves by using the word "one," i.e., "one would" and used "they" when referring to their coactors. When narrating situations possible to grasp, they used the terms "I" and "we." The most important situational factor that was revealed in these narratives was whether or not the nurses had a support group in which to share their thoughts. Without the support group, they reported difficulties acting in accordance with their ethical reasoning and feelings.

Adult↗