Biomedical subjects

L Jansson

Publications and source records attributed to L Jansson.

At least 73 records · Page 4Linked to original sources

PubMed1998

Angiotensin II and the endocrine pancreas: effects on islet blood flow and insulin secretion in rats.

An intrinsic angiotensin system has been described in the pancreas, with angiotensin II specific receptors being present on both exocrine, endocrine and vascular cells. The aim of the present study was to evaluate the effects of angiotensin II on insulin secretion and blood flow regulation in the pancreas. Blood flows were determined with a microsphere technique. Infusion of angiotensin II induced a dose-dependent reduction in both whole pancreatic and islet blood flow, which was most pronounced in the former. Administration of enalaprilate, an inhibitor of angiotensin-converting enzyme, and saralasin, a nonselective angiotensin II receptor antagonist, preferentially increased islet blood flow. The effects of angiotensin II on insulin release were examined by measuring insulin concentrations in the effluents from isolated perfused pancreata. In these preparations, enalaprilate affected neither basal nor glucose-stimulated insulin release, whereas angiotensin II delayed the first phase of insulin release in response to glucose. The effect of angiotensin II was probably due to initial marked vasoconstriction. The retardation of insulin release could be avoided by adding angiotensin II to the perfusion medium 20 min before glucose administration, i. e. so that the vasoconstriction had disappeared when glucose-stimulation began. The present study suggests that the angiotensin-system is important in regulation of islet blood flow and points to a pivotal role of islet blood perfusion for an adequate insulin release.

Angiotensin II↗

PubMed1998

Effects of the carbonic anhydrase inhibitor acetazolamide on splanchnic blood flow in anaesthetized rats.

The aim of the present study was to evaluate whether inhibition of the enzyme carbonic anhydrase with acetazolamide interfered with pancreatic islet and whole splanchnic blood perfusion in rats. Carbonic anhydrase is present both in the endocrine cells and, in particular, the endothelium of the pancreatic islet. Thiobutabarbital-anaesthetized, male Sprague-Dawley rats were used in all experiments, and acetazolamide (50 mg/kg body weight) was given to untreated control rats or rats pretreated with glucose, i.e. to normoglycaemic and hyperglycaemic animals. No acetazolamide-induced effects on blood glucose or serum insulin concentrations, mean arterial blood pressure, whole pancreatic or islet blood flow were seen in any of the animals. There were no effects on duodenal or colonic blood flow recorded in the control rats, whereas an increase in duodenal blood flow (P<0.02) was observed in the hyperglycaemic animals. A tendency to an increase was seen in colonic blood flow in hyperglycaemic animals, although this was not statistically significant (P = 0.069). Inhibition of carbonic anhydrase seems to induce only minor effects on pancreatic blood flow, while duodenal blood flow is slightly enhanced in hyperglycaemic animals.

Acetazolamide↗

PubMed1998

On CNS repair and protection strategies: novel approaches with implications for spinal cord injury and Parkinson's disease.

In the adult mammalian central nervous system lost nerve cells are not replaced and there is no regeneration of injured axons in white matter. Together, these two facts mean that there are no spontaneous reparative mechanisms in operation. Instead, the adult central nervous system copes with the risks of injuries and diseases by protective encapsulation in bone, by a multitude of neuroprotective mechanisms, and finally by the fact that many important functions are represented by a much larger number of neurons than minimally needed. The long life expectancy of a human being nevertheless means that the risk that the central nervous system is affected by disease, injury or other forms of insults for which it cannot fully compensate is relatively high. Experimentally, two strategies are being pursued in order to develop ways of minimizing various forms of CNS damage, namely neuroprotective and reparative strategies. Here we present a possible reparative intervention applicable to spinal cord injury based on multiple white-to-gray matter peripheral nerve bridge grafts and work based on the specific role of Nurr1 for dopamine neuron development, suggesting that development of ligands to transcription factor might be a new inroad to neuroprotective treatments in Parkinson's disease.

Adult↗

PubMed1998

B cell-deficient mice do not develop type II collagen-induced arthritis (CIA).

To investigate the role of B cells in the development of CIA, a model for rheumatoid arthritis, we investigated susceptibility to CIA in mice lacking B cells due to the deletion of the IgM heavy chain gene (muMT). The muMT deletion was backcrossed into two different CIA-susceptible strains, B10.Q and B10.RIII. Two different variants of the CIA model are inducible in these strains: in B10.Q with rat type II collagen (CII) and in B10.RIII with bovine CII. Homozygous deletion of the IgM gene led to the absence of B cells and dramatically reduced immunoglobulin levels compared with wild-type mice. The deletion of IgM totally abrogated development of CIA in both strains, although the anti-CII T cell response did not differ between the muMT and wild-type controls. We conclude that B cells play a crucial role in the development of CIA.

Animals↗

PubMed1998

Blood flow to the pancreatic islet parenchyma of the Atlantic hagfish (Myxine glutinosa).

The islet organ of the Atlantic hagfish, a cyclostome, phylogenetically is the most original islet parenchyma. It is well equipped with blood vessels, but lacks nerves. The aim of the present study was to evaluate the relative proportions between regional blood flows in these animals with a microsphere technique and with laser-Doppler flowmetry. As regards the results obtained in the kidneys, gills, and islet organ, the data were essentially the same found using both methods. Approximately 20% of the injected microspheres were found in the kidneys; when corrected for weight, the gill bodies and the islet organ were also found to have the same blood perfusion. The blood flow to the brain and that of the gut and the liver were only approximately 30% and 10%, respectively, of that to the kidney. Topical application of the nitric oxide donor, sodium nitroprusside failed to affect the islet blood flow. Apart from this observation, this non-innervated "primitive" islet parenchyma did not differ from that of the amply innervated mammalian islets with regard to their high basal blood perfusion.

Animals↗

PubMed1998

Effects of proximal vertical destructions on periodontal status and healing in adjacent proximal sites with horizontal destruction.

The purpose of the study was to investigate if the presence of vertical destruction in proximal sites influences periodontal status and healing in adjacent sites in the same proximal space without vertical destruction. The investigation was conducted as a retrospective study on a 3-year consecutive referral population of periodontitis-prone patients based on full-mouth oral radiographic examinations, probing pocket depth registrations and plaque scores. The analyses were performed by using regression analyses on a final sample of 1169 (periodontal status) and 1051 (periodontal healing) proximal sites in 163 patients. The relative radiographic attachment level (RRAL) in proximal horizontal sites did not depend on the type of destruction, vertical or horizontal, in the adjacent proximal sites. However, after non-surgical treatment, pocket-depth reduction in proximal sites with horizontal destruction was significantly reduced in the presence of a vertical destruction in the adjacent proximal site compared to the corresponding sites adjacent to a horizontal defect. It was concluded that marginal periodontal healing in proximal sites with horizontal destruction is impaired by the presence of a vertical destruction in the adjacent proximal site.

Adult↗

PubMed1998

Influence of age, hyperglycemia, leptin, and NPY on islet blood flow in obese-hyperglycemic mice.

This study aimed to elucidate possible age-related changes in islet blood perfusion in lean and obese C57BL/6 mice. Obese mice aged 1 mo were hyperglycemic and hyperinsulinemic and had an increased islet blood flow compared with age-matched lean mice. This augmented blood flow could be abolished by pretreatment with leptin. The islet blood perfusion was, in contrast to this, markedly decreased in obese 6- to 7-mo-old animals compared with age-matched lean mice. Reversal of hyperglycemia, but not hyperinsulinemia, in these obese mice with phlorizin normalized the islet blood flow. Spontaneous reversal of hyperglycemia, but not hyperinsulinemia, was seen in the 12-mo-old obese mice. Islet blood perfusion in obese mice at this age did not differ compared with lean mice. It is suggested that the initial increase in islet blood flow in obese mice is due to the leptin deficiency. The subsequent decrease in islet blood perfusion is probably caused by the chronic hyperglycemia. The described islet blood flow changes may be of importance for impairment of islet function in obese-hyperglycemic mice.

Aging↗

PubMed1998

Pancreatic islet blood perfusion in the nonobese diabetic mouse: diabetes-prone female mice exhibit a higher blood flow compared with male mice in the prediabetic phase.

The present study tested the hypothesis that changes in pancreatic islet blood flow correlate with the difference in diabetes incidence between male and female nonobese diabetic (NOD) mice. The blood flows were determined by a microsphere technique. In animals aged 10 and 14 weeks, the islet blood perfusion was 3-fold higher in female NOD mice compared with that in either age-matched male NOD mice or age- and sex-matched control ICR mice. At 5 weeks of age islet blood flow was similar in all groups. No differences between male and female NOD mice in whole pancreatic, duodenal, ileal, or colonic blood flows were observed at any time point. Administration of a bolus dose of aminoguanidine (a blocker of inducible nitric oxide synthase) to 10-week-old animals selectively and markedly decreased islet blood flow in female NOD mice, whereas islet blood flow in ICR mice and male NOD mice remained unaffected. Aminoguanidine did not affect mean arterial blood pressure or whole pancreatic blood flow in any of the groups. Injection of N(G)-methyl-L-arginine, an unspecific inhibitor of both constitutive and inducible nitric oxide synthase, markedly decreased whole pancreatic and islet blood flow to the same level in both male and female NOD mice. These combined findings suggest that diabetes-prone female NOD mice have an increased islet blood flow, which is mediated by an excessive production of nitric oxide formed by inducible nitric oxide synthase. The islet blood hyperperfusion may augment homing to the pancreatic islets of inflammatory cells and soluble factors involved in beta-cell destruction during the development of insulin-dependent diabetes mellitus in this animal model. The presently observed gender difference in the blood flow response could, therefore, at least partially explain why female NOD mice are more prone to develop hyperglycemia than the males.

Aging↗

PubMed1998

Capillary blood pressure in syngeneic rat islets transplanted under the renal capsule is similar to that of the implantation organ.

The aim of the present study was to measure capillary blood pressure and interstitial pressure in transplanted pancreatic islets and to correlate these measurements to capillary and tubular pressures in the adjacent kidney. For this purpose, 250 syngeneic islets were implanted under the renal capsule of WF rats and studied 1, 2, or 6 months after transplantation. Some of the animals studied after 1 and 2 months were streptozotocin (STZ)-induced diabetic. Measurements were performed during basal conditions or after an acute glucose-stimulation of insulin release. The hydrostatic pressures were determined in vivo by direct micropuncture. The islet transplant capillary pressure in normoglycemic animals was 6.9 +/- 0.4 mmHg (n = 9), 10.0 +/- 0.8 mmHg (n = 7), and 12.4 +/- 0.8 mmHg (n = 7) when measured 1, 2, and 6 months after implantation, respectively. Previous data from our laboratory showed that the normal capillary pressure of native rat pancreatic islets is approximately 3 mmHg. The blood pressure in kidney peritubular capillaries was 10-12 mmHg in both transplanted and control animals. Islet transplant interstitial pressures were 4-6 mmHg in the normoglycemic recipients at 1, 2, and 6 months after transplantation. Acute glucose stimulation had no effect on islet transplant interstitial pressure or peritubular or transplant capillary blood pressures. Capillary pressures in the islet grafts were slightly increased 1 month after transplantation in STZ-induced diabetic rats, and this was associated with an increased blood perfusion of the transplants. However, 2 months after transplantation there were no differences in transplant capillary blood pressure between diabetic and normoglycemic animals. The graft interstitial pressure was, on the contrary, decreased in the diabetic animals 2 months after transplantation. We concluded that the capillary blood pressure in islets implanted under the renal capsule was similar to that of the implantation organ, which was three to four times higher than that normally found in native islets.

Animals↗

PubMed1998

Measurements of oxygen tension in native and transplanted rat pancreatic islets.

This study was performed to measure the oxygen tension before and after revascularization of pancreatic islets transplanted beneath the renal capsule and to investigate to what extent this was affected by acute and chronic hyperglycemia. In addition, the oxygen tension in islets within the pancreas was determined. PO2 was measured with a modified Clark electrode (tip 2-6 microm o.d.). Within native pancreatic islets, the mean PO2 was higher (31-37 mmHg) than within the exocrine pancreas (20-23 mmHg). The mean oxygen tension in the transplanted islets the day after implantation was half of that recorded in native islets (14-19 mmHg) and did not differ between normoglycemic and diabetic recipients. At 1 month after transplantation, when revascularization had occurred, the mean PO2 in the islet grafts was 9-15 mmHgf in normoglycemic animals but was lower (6-8 mmHg) in diabetic animals, whereas the blood perfusion of the transplants, as measured with laser-Doppler flowmetry (probe diameter 0.45 mm), was similar in both groups. The mean oxygen tension in the superficial renal cortex surrounding the implanted islets was similar in all groups and remained stable at 13-21 mmHg. Intravenous administration of D-glucose (1 g/kg) did not affect the oxygen tension in any of the investigated tissues. We conclude that the mean PO2 in islets implanted under the renal capsule is markedly lower than in native islets, not only in the immediate posttransplantation period but also 1 month after implantation, i.e., when revascularization has occurred. Furthermore, persistent hyperglycemia in the recipient leads to a further decrease in graft oxygen tension. To what extent this may contribute to islet graft failure is at present unknown.

3-O-Methylglucose↗

PubMed1998

Parenthood as talked about in Swedish ante- and postnatal midwifery consultations. A qualitative study of 58 video-recorded consultations.

In order to explore the manner in which parenthood was discussed in midwifery consultations, 58 video-recorded consultations were analysed. A content analysis revealed a variety of topics concerning conversation on parenthood--topics of an intimate nature and discussions from a societal perspective. Parenthood was not of primary importance in visits, which were mostly directed by the midwives. A phenomenological hermeneutic analysis of the meaning of being a mother revealed a complex and difficult situation of being both needed and dependent. The meaning of being a father revealed a struggle between distancing from and closeness to the child. The mate relationship was indicated as important and under strain. The metaphor of the 'spiders web', where the mother is the spider with the child mostly on her back, the father entering the web on her terms, summarizes the understanding. The results from this study could provide a basis for reflection on the status of the topic of parenthood, on the meaning of being a mother and a father disclosed in the consultations, and ultimately on the organization of ante- and postnatal midwifery care.

Adult↗

PubMed1998

Skilled carers' ways of understanding people with Alzheimer's disease.

Five carers in a group dwelling for people with dementia were observed and interviewed concerning their interactions with five residents with Alzheimer's disease. The tape-recorded and transcribed data were analyzed as text. The carers' personal ways of achieving understanding were defined as: affect attunement; affect attunement and completing a puzzle through explanatory connections of observation, knowledge about the residents' life histories and behavior at the group dwelling; and affect attunement within the context of caring as an intrinsic end. Personal experience from childhood and motherhood, knowledge about the residents' life history and the nature of the disease, and personal talent seemed to form these carers' ways of achieving understanding.

Adult↗

PubMed1998

Number and frequency of bitewing radiographs and assessment of approximal caries in 14-to-19-year-old Swedish adolescents.

The hypothesis of the present study was that previous experience of caries may serve as an indicator for individualised bitewing examinations in 15-19-old adolescents. One hundred adolescents, all 19 years old, were randomly selected from the files of public dental clinics in the County of Orebro. For 93 adolescents the total number of radiographs were summed for every patient from the age of 3 to 19 by assessing the files of public dental clinics and by assessing the files of the dental radiology department. All sets of bitewing radiographs from 14 up to and including the age of 19 were assessed with respect to approximal caries. The average number of intraoral radiographs exposed in a patient from the age of 3 through 19 was 24.4. It was shown that 70 to 80% of 14-19-year-old-adolescents had had a bitewing examination every year. The decision to perform a bite-wing examination in a 15-year-old was significantly correlated to the number of surfaces with initial caries at the age of 14. In the other age groups, none of the investigated variables was found to be significantly correlated to the performance of radiographic examinations.

Adolescent↗

PubMed1997

Dopamine neuron agenesis in Nurr1-deficient mice.

Dopamine neurons of the substantia nigra and ventral tegmental area regulate movement and affective behavior and degenerate in Parkinson's disease. The orphan nuclear receptor Nurr1 was shown to be expressed in developing dopamine neurons before the appearance of known phenotypic markers for these cells. Mice lacking Nurr1 failed to generate midbrain dopaminergic neurons, were hypoactive, and died soon after birth. Nurr1 expression continued into adulthood, and brains of heterozygous animals, otherwise apparently healthy, contained reduced dopamine levels. These results suggest that putative Nurr1 ligands may be useful for treatment of Parkinson's disease and other disorders of midbrain dopamine circuitry.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1997

Thought disorder in schizophrenic and control adoptees and their relatives.

BACKGROUND: Previous research showed significantly elevated levels of thought disorder in the relatives of persons with schizophrenia, as well as in the persons with schizophrenia themselves. Comparisons of schizophrenic and control adoptees and their respective relatives provide a method for minimizing the confounding of genetic and environmental sources of familial resemblance and for elucidating whether the elevated levels of thought disorder in persons with schizophrenia and their relatives reflect the influence of shared genetic factors, shared environmental factors, or both. The present study provides the first such adoption-sample data on an operationally defined measure of thought disorder. METHODS: Speech samples elicited by standard interview questions from schizophrenic and control adoptees and their respective biological and adoptive relatives were tape-recorded. Verbatim transcripts of these speech samples were scored, while unaware of the personal or family diagnoses of the subjects, using the Thought Disorder Index (TDI). RESULTS: The mean TDI scores were significantly higher in schizophrenic than in control adoptees and in biological relatives of the schizophrenic adoptees than in the biological relatives of the control adoptees, whereas the respective groups of adoptive relatives did not differ significantly. The differences were most marked for the samples of biological sibs and half sibs, which were larger and more representative than the samples of parents. CONCLUSION: Results suggest that the elevated TDI scores in the relatives of persons with schizophrenia that have been found in other studies reflect the operation of genes increasing the liability for schizophrenia, rather than the rearing experiences that were shared in common with schizophrenic probands.

Adolescent↗

PubMed1997

Gastric inhibitory polypeptide and splanchnic blood perfusion: augmentation of the islet blood flow increase in hyperglycemic rats.

The aim of the study was to investigate how the incretin candidate hormone gastric inhibitory polypeptide (GIP) affects splanchnic blood flow, especially pancreatic islet blood flow. For this purpose, male Sprague-Dawley rats were injected intravenously with either saline or GIP (5 or 15 micrograms/kg body weight) 10 min before blood flow measurements by a microsphere technique. Furthermore, 3 min before the blood flow measurements, 1 ml of either saline or 30% D-glucose was given intravenously. All glucose-injected animals were markedly hyperglycemic (> 20 mmol/liter) at the time of the blood flow measurements. Both doses of GIP potentiated basal and glucose-stimulated insulin release. In the normoglycemic rats, the lowest dose of GIP did not affect the blood perfusion to any of the investigated organs. The highest dose of GIP decreased whole pancreatic and duodenal blood flow, whereas islet blood flow was unaffected. As a result, fractional islet blood flow was increased. In the hyperglycemic rats, where the islet blood flow was increased compared with control animals, both doses of GIP further enhanced islet blood flow. No effect on pancreatic, fractional islet, or duodenal blood flow was seen after GIP administration to hyperglycemic animals. It is concluded that administration of GIP can further augment the glucose-induced stimulation of islet blood flow. This may contribute to facilitating release of insulin from the islets.

Animals↗

PubMed1997

Inhibition of nitric oxide formation by aminoguanidine: an attempt to prevent insulin-dependent diabetes mellitus.

1. Insulin-dependent diabetes mellitus is an autoimmune disease leading to pancreatic beta-cell destruction, an event that may, at least partially, be induced by the formation of nitric oxide. 2. Under the influence of cytokines, the enzyme nitric oxide synthase is induced. 3. Blockage of the inducible form of nitric oxide synthase has been found to protect against insulin-dependent diabetes mellitus in some animal models. 4. Aminoguanidine has been found to be a fairly specific inhibitor of cytokine-inducible nitric oxide synthase. 5. Aminoguanidine may reduce the blood flow to the pancreatic islets in vivo and, at higher concentrations, also impair insulin secretion by the beta-cells,--which may make the compound less useful in attempts to prevent insulin-dependent diabetes mellitus.

Animals↗

PubMed1997

Relationship between apical and marginal healing in periradicular surgery.

OBJECTIVE: The purpose of the present study was to evaluate the relationship between apical and marginal periodontal healing after periapical surgery. STUDY DESIGN: The investigation was conducted on 59 patients referred for periradicular surgery. A radiographic examination as well as assessments of periodontal attachment and pocket depth of teeth undergoing surgery and control teeth were performed at the time of surgery and 1 year after surgery. The radiographic periapical healing pattern was evaluated. RESULTS: After an observation time of 1 year, 85% of the healing patterns were classified as successful or uncertain. Teeth within the surgical area showed a significant loss of clinical attachment during the observation period. The mean clinical attachment loss in teeth with an unsuccessful healing was 0.85 mm and differed significantly from successfully healed cases (mean, 0.15 mm). CONCLUSIONS: A persisting endodontic infection may be regarded as a contributing risk factor for a progressing marginal attachment loss.

Adult↗