Biomedical subjects

Leif Jansson

Publications and source records attributed to Leif Jansson.

15 recordsLinked to original sources

PubMed2003

[Severe vascular dysfunction shown in transplanted islets].

Despite recent advances in clinical islet transplantation, a surprisingly large number of islets (approximately 1 million) are still required to obtain insulin independence in type 1 diabetes. The reasons for this are obscure and likely multifactorial. One explanation may be disturbances in engraftment of the transplanted islets, i.e. the adaptation of the islet transplant to its new surroundings with regard to e.g. revascularization and blood perfusion. Endogenous islets have a dense glomerular-like angioarchitecture. Transplantation of isolated islets causes a disruption of their vascular connections, making the islets dependent on the formation of new blood vessels for optimal function. Evidence from experimental islet transplantation indicates an insufficient revascularization of transplanted islets with subsequent chronically decreased blood perfusion and oxygen tension, which has metabolic consequences within the tissue.

Animals↗

PubMed2003

Impaired revascularization of transplanted mouse pancreatic islets is chronic and glucose-independent.

BACKGROUND: Pancreatic islets are avascular immediately after transplantation and depend on revascularization. Recently, the authors found decreased vascular density in mouse islets 1 month after implantation into nondiabetic recipients. This study investigated possible differences in revascularization between islets implanted into nondiabetic and diabetic recipients, and also evaluated changes in vascular density up to 6 months posttransplantation. METHODS: Islets were syngenically transplanted beneath the renal capsule of normoglycemic or alloxan-diabetic C57BL/6 mice. One to 6 months later, the animals were killed and the grafts removed. Histologic slides were prepared and stained with Bandeiraea simplicifolia. RESULTS: The vascular density in all transplanted islets was decreased compared with native islets. There were no differences in the islet graft vascular density between nondiabetic and diabetic animals. No improvement over time occurred. CONCLUSIONS: The vascular density is decreased in islets implanted to cure diabetic recipients. No improvement occurs in transplanted islets after 1 month posttransplantation.

Animals↗

PubMed2003

Role of superoxide anion in pancreatic islet blood flow regulation in anesthetized rats.

The aim of the investigation was to study the influence of the superoxide anion on pancreatic islet blood flow in rats. For this purpose, blood flow measurements were conducted with a microsphere technique 10 min after intravenous administration of different doses of superoxide dismutase (5, 15, 50, 100 or 1000 kU/kg body weight). In separate experiments, diethyldithiodicarbamate, an inhibitor of endogenous superoxide dismutase, was given to nontreated control rats or to rats subjected to a bilateral abdominal vagotomy before the injection. Only the highest dose of superoxide dismutase increased both whole pancreatic and islet blood flow. A 50% augmentation of fractional islet blood flow was seen. Administration of diethyldithiocarbamate induced marked hyperglycemia, which was partly prevented by vagotomy. Diethyldithiocarbamate decreased the whole pancreatic blood flow, while islet blood flow was maintained in both control and vagotomized rats. Consequently, a pronounced increase in fractional islet blood flow was noted in both these groups. We conclude that administration of superoxide dismutase and its inhibitor diethyldithiocarbamate influences pancreatic blood perfusion. In particular, superoxide dismutase causes a general increase in the whole pancreatic and islet blood flow, and an augmented fractional islet blood flow, presumably by a decrease in the local concentration of O(2)(z.rad;-), leading to increased concentration of NO. Diethyldithiocarbamate, on the other hand, by increasing the levels of O(2)(z.rad;-), decreases the whole pancreatic blood flow, whereas islet blood flow remains unaffected.

Anesthesia↗

PubMed2003

Caerulein-induced pancreatitis and islet blood flow in anesthetized rats.

BACKGROUND: Microcirculatory mechanisms have been suggested to be involved in the development of acute pancreatitis. Islet blood flow has not previously been studied in this disease. The present study aimed to investigate the effects of caerulein-induced pancreatitis on pancreatic blood perfusion, especially islet blood flow. MATERIALS AND METHODS: Continuous 4 h caerulein-infusion was used to induce mild, edemateous pancreatitis in anesthetized Sprague-Dawley rats. Some animals were then given an additional 2 h infusion of saline. Thus, at 4 or 6 h after initiating caerulein infusion the blood flow to the pancreas, pancreatic islets, and intestines was measured with a microsphere technique. RESULTS: All infused animals demonstrated an edemateous pancreatitis, without hemorrhages. Both total pancreatic and islet blood flow was increased after the 4-h infusion. However, the increase was less pronounced in the islets. After an additional 2 h with only saline infused, the blood flow values in rats initially infused with caerulein were lower than at 4 h, but total pancreatic blood was still higher than in control rats. No effects on intestinal blood flow values were seen. CONCLUSIONS: Pancreatic islet blood flow in rats with mild edematous pancreatitis is increased, but not to the same extent as that in the whole pancreas.

Amylases↗

PubMed2003

Systemic disorders in patients with periodontal disease.

BACKGROUND, AIMS: Over the past 10 years several studies have been published pointing towards a relationship between periodontal disease and various systemic disorders or diseases. The purpose of this retrospective study was to investigate the occurrence of self-reported systemic disorders in patients referred to a specialist clinic for periodontal treatment and to explore possible relationships between general health and periodontal disease severity in this population. MATERIAL AND METHODS: Data were collected from the dental records and the health questionnaires of 1006 subjects. Stepwise multiple linear regression analyses were adopted to calculate correlations between systemic disorders as independent variables and number of remaining teeth and the relative frequency of periodontal pockets of 5 mm or more, respectively, as the dependent variable. RESULTS: The number of remaining teeth was significantly and positively correlated to the presence of cardiovascular disease, diabetes and rheumatoid disease after adjustment for age, sex and smoking. The relative frequency of diseased sites, however, was not significantly correlated to any one of the investigated systemic health disorders. CONCLUSION: No significant associations between investigated systemic disorders and periodontal disease severity were found if the relative frequency of deep periodontal pockets was used as the clinical parameter for periodontal disease severity. However, cardiovascular disease, diabetes and rheumatoid disease were found to be significantly correlated to number of lost teeth, which may represent one aspect of periodontal health. This result held true in nonsmokers only.

Adult↗

PubMed2003

K(ATP) channels and pancreatic islet blood flow in anesthetized rats: increased blood flow induced by potassium channel openers.

K(ATP) channels are important for insulin secretion and depolarization of vascular smooth muscle. In view of the importance of drugs affecting K(ATP) channels in the treatment of diabetes, we investigated the effects of these channels on splanchnic blood perfusion in general and pancreatic islet blood flow in particular. We treated anesthetized Sprague-Dawley rats with the K(ATP) channel openers diazoxide or NNC 55-0118 or the K(ATP) channel closer glipizide. Both diazoxide and NNC 55-0118 dose-dependently increased total pancreatic and islet blood flow in the presence of moderate hyperglycemia, but had no effects on the blood perfusion of other splanchnic organs. Diazoxide markedly lowered the mean arterial blood pressure and thus increased vascular conductance in all organs studied. NNC 55-0118 had much smaller effects on the blood pressure. Glipizide did not affect total pancreatic blood flow, but decreased islet blood flow by 50% in the presence of hypoglycemia. We conclude that K(ATP) channels actively participate in the blood flow regulation of the pancreatic islets and that substances affecting such channels may also influence islet blood flow.

Adenosine Triphosphate↗

PubMed2002

Prediction of marginal bone loss and tooth loss--a prospective study over 20 years.

AIM: The purpose of the study was to investigate the influence of potential risk predictors/risk factors on the longitudinal marginal bone loss and tooth loss over 20 years. MATERIAL AND METHODS: A clinical and radiographic investigation of a sample of 513 individuals was performed in 1970 and 1990. Stepwise multiple regression analyses were adopted to calculate the influence of the potential risk predictors/risk factors on the longitudinal marginal bone loss and tooth loss. RESULTS: Russell's Periodontal Index in 1970 and smoking were significantly and positively correlated to longitudinal bone loss. Russell's Periodontal Index, marginal bone loss and Plaque Index at baseline were positively and significantly correlated to the longitudinal tooth loss, whilst age, the number of missing teeth in 1970 and the number of school years showed a significant negative correlation to number of teeth lost between 1970 and 1990. CONCLUSIONS: Smoking was found to be a significant risk factor in marginal bone loss, while plaque was a risk factor in tooth loss. However, the regression models explained a low percentage of the total variance, especially for marginal bone loss.

Adolescent↗

PubMed2002

Influence of smoking on marginal bone loss and tooth loss--a prospective study over 20 years.

AIMS: The aim was to investigate the influence of smoking on longitudinal marginal bone loss and tooth loss in a prospective study over 20 years. In addition, the effect of cessation of smoking on bone loss and the interaction between smoking, plaque and marginal bone loss were evaluated. MATERIAL AND METHODS: A total of 507 dentate individuals from an epidemiological study were examined in 1970 and 1990. The clinical investigation included registration of number of remaining teeth and presence of plaque. The marginal bone level was determined by assessments on the proximal surfaces on the radiographs from 1970 and 1990. The marginal bone loss was defined as the difference in marginal bone level over 20 years. The subjects were interviewed about smoking habits. Stepwise multiple regression analyses were adopted to calculate the influence of the independent variables on longitudinal marginal bone loss and tooth loss. RESULTS: In 1970, 50.7% of the subjects were smokers, while the corresponding relative frequency in 1990 had decreased to 31.0%. Smoking was significantly correlated to an increased marginal bone loss over 20 years. Individuals who stopped smoking between 1970 and 1990 lost significantly less marginal bone during this period than those who declared that they smoked during the 20-year period. Smoking was not found to be significantly correlated to tooth loss over 20 years. CONCLUSIONS: The results support the hypothesis that smoking is a significant risk factor of periodontal disease.

Adult↗

PubMed2002

Relationship between oral health and mortality rate.

BACKGROUND/AIMS: Some symptoms of diseases or causes of death are often related to oral health, especially cardiovascular diseases. The purpose of this study was to investigate the relationship between poor oral health and mortality risk, especially when cases of fatal cardiovascular diseases were excluded. MATERIAL AND METHODS: An odontological investigation was made on a sample of 1393 individuals, aged 18-65 years, in 1970 in the County of Stockholm with a follow-up in 1997, when the mortality rate and causes of death in the sample during the time period 1971-1996 were registered. Oral health was defined as a sum of scores for number of missing teeth, apical lesions, caries lesions and marginal bone loss. RESULTS: A significant correlation was found between poor oral health and an increased mortality risk even when persons dying from cardiovascular diseases were excluded from the analyses. CONCLUSION: Poor oral health was found to be a risk indicator of all-cause mortality. The lack of specificity of the associations between oral health and mortality strengthens the hypothesis that the significant correlations could be explained by not identified confounding factors.

Adolescent↗

PubMed2002

Microdialysis measurements demonstrate a shift to nonoxidative glucose metabolism in rat pancreatic islets transplanted beneath the renal capsule.

BACKGROUND: We aimed to use microdialysis to assess, for the first time, the internal milieu of pancreatic islet grafts. METHODS: One month after transplantation, microdialysis probes were inserted into syngeneic rat islet transplants (500-700 islets) placed beneath the renal capsule of nondiabetic or diabetic recipients. The number of grafted islets was purposely chosen not to cure the diabetic recipients. RESULTS: During an intravenous glucose challenge, insulin concentrations increased in parallel in serum and in the graft interstitium of nondiabetic animals suggesting the existence of a functionally well-established vascularization. Diabetic recipients had both a lower serum and dialysate insulin concentration than normoglycemic animals. The lactate/pyruvate ratios were determined in the dialysates as a measure of the degree of anaerobic metabolism in the islet grafts. Lactate/pyruvate ratios were between 50 and 100 in grafts of both nondiabetic and diabetic recipients, and they almost doubled in response to the intravenous glucose challenge in the grafts of nondiabetic recipients. In comparison, lactate/pyruvate ratios were approximately 12 in the medium of cultured islets incubated at low glucose (5.6 mmol/L) or high glucose (16.7 mmol/L) concentrations. CONCLUSIONS: The microdialysis technique has proven to be a valuable tool for evaluating the internal environment of islet transplants. Moreover, the high lactate/pyruvate ratio suggests that islet grafts have an increased anaerobic glucose metabolism.

Animals↗

PubMed2002

Glucose-induced islet blood flow increase in rats: interaction between nervous and metabolic mediators.

This study investigated the mechanisms for glucose-induced islet blood flow increase in rats. The effects of adenosine, adenosine receptor antagonists, and vagotomy on islet blood flow were evaluated with a microsphere technique. Vagotomy prevented the islet blood flow increase expected 3, 10, and 20 min after injection of glucose, whereas theophylline (a nonspecific adenosine receptor antagonist) prevented the islet blood flow increase from occurring 10 and 20 min after glucose administration. Administration of selective adenosine receptor antagonists suggested that the response to theophylline was mediated by A1 receptors. Exogenous administration of adenosine did not affect islet blood flow, but local accumulation of adenosine, induced by the adenosine uptake inhibitor dipyridamole, caused a doubling of islet blood flow. In conclusion, the increased islet blood flow seen 3 min after induction of hyperglycemia is caused by the vagal nerve, whereas the increase in islet blood perfusion seen at 10 and 20 min after glucose administration is caused by both the vagal nerve and adenosine.

Adenosine↗

PubMed2002

Histological markers for endothelial cells in endogenous and transplanted rodent pancreatic islets.

BACKGROUND/AIMS: To obtain a selective marker to identify endothelial cells is difficult, due to the heterogeneity of these cells. Most described markers perform well in some applications, but fail in others. The aim of this study was to identify a selective and specific marker for rodent microvascular endothelial cells, especially for use in studies on the vascular system of pancreatic islets. METHODS: A biotin-labelled form of the lectin Bandeiraea or Griffonia simplicifolia in combination with a streptAB-Complex with alkaline phosphatase was used to stain endothelium in paraffin-embedded tissue sections from C57BL/6 mice, Sprague-Dawley or Wistar-Furth rats. RESULTS: We were consistently able to selectively stain microvascular endothelial cells in lungs, small intestines, white and brown adipose tissue, pancreas and islets of Langerhans with the lectin Bandeiraea simplicifolia. Furthermore, we were able to visualise the vasculature in syngenically transplanted islets of Langerhans in Wistar-Furth rats and C57BL/6 mice. Attempts to stain rodent endothelial cells with antibodies against CD34, CD31, CD200, Ox43, von Willebrand factor and the lectin Ulex europaeus were not uniformly successful. CONCLUSION: The lectin Bandeiraea simplicifolia is a versatile marker for rodent endothelial cells, and may be used to study revascularisation after transplantation of pancreatic islet in rodents.

Animals↗

PubMed2002

Decreased vascular density in mouse pancreatic islets after transplantation.

An adequate revascularization is crucial for islet survival and function after transplantation. Previous studies have suggested that islet revascularization is concluded within 14 days after transplantation. We investigated if the vascular density of transplanted islets and endogenous pancreatic islets differs. Cultured islets were syngeneically transplanted into the kidney, liver, or spleen of C57BL/6 mice. One month later, the graft-bearing organ was removed, and histological specimens were prepared and stained for endothelium with the lectin Bandeiraea simplicifolia. Pancreata from nontransplanted control animals were prepared similarly. Uniform staining of endothelium within the grafts and endogenous islets was obtained. The vascular density was markedly decreased in transplanted islets at all implantation sites, but preferentially in islets implanted into the spleen. The vascular density in the connective tissue surrounding the transplanted islets was very high compared with that of graft intra-islet capillaries. A much lower vascular density was detected in connective tissue surrounding implanted microspheres of a size similar to the islets, which suggests that the islets per se induced blood vessel formation in their vicinity. We conclude that the vascular density in revascularized transplanted islets is markedly decreased compared with endogenous islets. This has potential implications for islet graft metabolism and function.

Animals↗

PubMed2002

Multiple injections of coloured microspheres for islet blood flow measurements in anaesthetised rats: influence of microsphere size.

We investigated if coloured microspheres could be used for repeated measurements of pancreatic islet blood flow in rats. An initial injection of 1.0-1.5 x 10(5) microspheres (black colour), with a size of 10 or 15 microm, was made into the ascending aorta, while an arterial reference sample was collected from the femoral artery. Twelve min later, 1 ml of saline or 30% D-glucose was injected intravenously. Three min after this injection a second injection of 10- or 15-microm microspheres (green colour) was given. The animals were then killed, and the pancreas and adrenals were removed and samples (150-200 mg) were secured from the duodenum, ileum, colon, right kidney and liver. The microsphere contents were determined with the aid of a freeze-thawing technique and blood flow values were calculated. Our results suggest that 10-microm microspheres, but not 15-microm microspheres, provide reproducible islet and total pancreatic blood flow measurements when repeatedly injected. Values for the blood flow to the intestines, kidney and liver were less sensitive to the size of the microspheres. We conclude that repeated administration of 15-microm microspheres induces a high risk for erroneous islet and total pancreatic blood flow measurements, whereas two such measurements can be performed if 10-microm microspheres are used.

Animals↗

PubMed2002

Marginal bone loss and tooth loss in a sample from the County of Stockholm--a longitudinal study over 20 years.

The purpose of the study was to assess the degree of marginal alveolar bone loss and tooth loss in a longitudinal study over a period of 20 years. In 1970 a medical and odontological study on a stratified sample of the population of the County of Stockholm aged 18-65 years started. Twenty years later a new odontological investigation was performed on the 513 subjects who wanted to take part once more and who had at least five remaining teeth. The mean distance between the marginal bone level and the cemento-enamel junction measured on the radiographs in 1970 (MBL) was 13.8% of the root length. The mean bone loss during the 20-year period (MBD) was about 10%, corresponding to a mean annual marginal bone loss of about 0.1 mm. The MBD-values were significantly positively correlated to the MBL-values. The mean number of remaining teeth was 24.7 in 1970 and 21.8 in 1990. A significant positive correlation existed between the number of teeth lost between 1970 and 1990 and the mean MBD-value. In stepwise multiple regression analyses, the MBL-value was the only independent variable positively correlated to the MBD-value, while the number of teeth lost between 1970 and 1990 was significantly correlated to age and the MBL-value.

Adolescent↗