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Biomedical subjects

L Jansson

Publications and source records attributed to L Jansson.

At least 163 records · Page 9Linked to original sources
PubMed1993

Development of periapical lesions.

The purpose of the present study was to follow the development of periapical lesions both radiographically and histologically in infected teeth with open and sealed root canals. The mandibular premolars from five adult monkeys were used in the experiment. Sealed infected teeth developed radiographic signs of periapical pathosis significantly earlier than unsealed teeth. Although, histological signs of pathology could be seen periapically at earlier observation periods, sealed teeth consistently developed these changes earlier than unsealed teeth. Furthermore, the histological periapical pathology differed somewhat between the two groups in that unsealed teeth showed a multi-focal diffuse pattern of spreading.

Animals↗
PubMed1993

Tissue formation on cementum surfaces in vivo.

The purpose of the present investigation was to study cell colonization of and tissue formation on denuded (anorganic) cementum surfaces as well as denuded demineralized cementum surfaces. The most conspicuous finding was the distinctly different pattern of cell colonization and subsequent tissue formation on etched and non-etched denuded cementum surfaces. Non-etched cementum surfaces displayed a limited number of resorbing cells and resorption lacunae, while etched cementum surfaces displayed an abundance of fibroblast-like cells in varying stages of activity in a meshwork of fibres, probably collagenous. These fibres were organized in a layer parallel to the root surface. This appearance of a fibrous capsule-like structure has previously been associated with periodontal healing with a non-functional repair-tissue. It may be concluded, based on the present results that, a cementum surface in which collagen fibers have been exposed presents a suitable surface for colonization by mesenchymal cells. However, if collagen fibers are not exposed in the cementum surface leaving mineralized surface, mesenchymal cells appear not to be able to attach.

Acid Etching, Dental↗
PubMed1992

Characterization of a spontaneously occurring arthritis in male DBA/1 mice.

OBJECTIVE: We studied the incidence, severity, histopathologic features, and status of infection in a spontaneous polyarthritis which occurs in male DBA/1 mice. METHODS: Over a 25-week period, the arthritis was evaluated macroscopically in naive mice of different strains. The histopathology was evaluated at different phases of the disease. Virologic and bacteriologic investigations were performed. RESULTS: The arthritis occurs in approximately 80% of aging male DBA/1 mice. The disease is chronic and destructive, and the affected joints are characterized by synovial lining proliferation and infiltration of inflammatory cells, mainly mononuclear. The susceptibility appears to be dependent on both sex-linked and non-sex-linked genes, since female DBA/1 mice are not affected and since male BALB/c housed in the same colony are only marginally affected. CONCLUSION: This first description of a spontaneous arthritis in aging male DBA/1 mice should provide new opportunities to study general features of a chronic and intermittent arthritis in a well-characterized strain, in which no generalized aberrations of the immune system have been described.

Aging↗
PubMed1992

Adaptive response in beta-cell function in pancreatic islets isolated from partially pancreatectomized rats.

Before clinical onset of insulin-dependent diabetes mellitus a decreasing pancreatic beta-cell mass maintains glucose homeostasis. We currently aimed to study the function of pancreatic islets isolated 2 weeks after a 60% partial pancreatectomy (P) or after a sham operation (S) on adult rats. Experiments on the islets were subsequently performed acutely (day 0) and after 1 week (day 7) of tissue culture in medium RPMI 1640 (11.1 mM glucose) + 10% calf serum. There was no difference in the body weight 2 weeks after surgery. The pancreatic remnant weight of the P rats was 35% less than the pancreatic weight in the S rats. The islet DNA content was 25% higher in the islets of the P rats on day 0, indicating a stimulated islet growth. However, this difference did not remain after culture for 7 days. Islet proinsulin mRNA content and (pro)insulin biosynthesis rates were slightly increased in the islets of P rats on day 0, which could be due to the increased islet mass. The islet insulin content was not different on day 0, but was higher after culture in the islets of the P rats. The islet rates of glucose oxidation and insulin release were markedly higher in the P rats on day 0, suggesting a selective effect on these processes. A higher glucose oxidation rate was, however, not evident on day 7. The relative fraction of insulin-positive cells was slightly lowered in the islets of the P rats on day 0.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1992

Dissociation between the blood flow response of transplanted pancreatic islets and that of the implantation organ.

The aim of this study was to investigate if the blood flow of transplanted islets is affected by the implantation organ or regulated by the grafted islets themselves. For this purpose adult rats were partially depancreatized and islets were isolated from the excised pancreatic tissue, maintained in tissue culture for 7 days, and subsequently 500 islets were implanted into the same animal beneath the renal capsule. Four weeks after transplantation, the rats were given an i.v. injection of either saline or furosemide (7.5 mg/kg body weight). Fifteen minutes later the blood perfusion of the whole left kidney and its islet grafts were measured separately with a microsphere technique. Also, the blood flow values of the pancreatic remnant were determined. Rats that were partially pancreatectomized and transplanted showed a decreased whole pancreatic blood flow in the pancreatic remnant after furosemide injection, whereas the blood flow to the islets was not significantly affected. Furosemide also increased the blood flow to the kidney but had no effect on the blood perfusion of the pancreatic islets grafted into the same kidney. These results suggest that the blood flow of an islet graft does not necessarily change in concert with the blood flow of the implantation organ. This may reflect differences in the blood flow regulation between the grafted islets and the implantation organ. In addition, it could be that the vascular system developing in the transplanted islets originates from either the islets or the kidney capsule, rather than from the kidney parenchyma. This may account for a different blood flow regulation.

Animals↗
PubMed1992

Pancreatic islet blood flow after syngeneic pancreaticoduodenal transplantation in rats. Differences between the blood perfusion of the native and the transplanted gland.

Inbred male Sprague-Dawley rats were transplanted with syngeneic pancreaticoduodenal grafts. Diabetes was induced in some of the recipient animals by an i.v. injection of streptozotocin one week before transplantation, while the remaining control rats were untreated, and thus had both an intact native and a transplanted pancreas. The left kidney of the recipient was removed and its blood vessels were used for the graft vascular anastomosis. The graft duodenum was sutured end-to-side to the ileum of the recipient. Two weeks after transplantation the rates of blood flow through both the native and transplanted pancreas and duodenum were measured. The blood perfusion of the whole pancreas and the islets was higher in the tx than in the native gland, although no difference was seen with regard to the duodenum. Administration of glucose to control animals had no effect on either native or tx whole pancreatic or intestinal blood flow. However, the islet blood flow through the native pancreas was increased in response to glucose, while that of the tx gland remained unchanged. The combined data show that the blood flow of a tx pancreas is slightly higher than that of the native organ, and that the response of the islet blood perfusion to glucose administration differs between the native and tx pancreas. This suggests that islets in the tx pancreas 14 days after transplantation are not subject to the same blood flow regulatory mechanisms as native islets.

Animals↗
PubMed1992

Genetic, hormonal and behavioural influence on spontaneously developing arthritis in normal mice.

DBA/1 male mice develop arthritis spontaneously at the age of 4 months. The affected joints show cell-rich pannus formation without T cell infiltration and only limited MHC class II expression. Specific pathogen-free DBA/1 mice from different sources developed the same disease. Analyses of inbred mouse strains with various genetic backgrounds and F1 hybrids revealed that the disease is genetically dependent of DBA/1 recessive genes. However, F1 hybrids between DBA/1 and BXSB spontaneously developed arthritis with earlier onset than DBA/1 mice, suggesting that the BXSB autoimmune gene background had both permissive and contributing effects on the development of arthritis. The complete male preponderance for disease susceptibility was investigated by castration and testosterone treatment of DBA/1 males. No arthritis developed after castration and disease susceptibility was restored by testosterone treatment. Arthritis developed only where more than two males were kept in cages, suggesting an influence by aggressive behaviour. Thus, the spontaneous development of arthritis is dependent on hormonal and behavioural mediated effects and differs from experimental models for rheumatoid arthritis such as type II collagen-induced arthritis and pristane-induced arthritis. We conclude that the spontaneously developing arthritis in the normal DBA/1 strain may be more useful as a disease model for osteoarthritis than for rheumatoid arthritis.

Animals↗
PubMed1992

Oestrogen-induced suppression of collagen arthritis; 17 beta-oestradiol is therapeutically active in normal and castrated F1 hybrid mice of both sexes.

The F1 hybrid mouse strain, from B10Q and DBA/1 parentals (the QD strain), is highly susceptible to induction of type II collagen-induced arthritis, an experimental model for rheumatoid arthritis. Males are more susceptible than females. Oophorectomy enhances susceptibility to arthritis and treatment with physiological doses of 17 beta-oestradiol (E2) suppresses disease. E2 treatment lowers the incidence of arthritis also in non-castrated and castrated males, showing that the anti-arthritic effect by oestrogen is not dependent on either sex hormone imprinting effects or interference with male sex hormones. Testosterone treatment of normal females, but not of castrated females, exaggerated development of the disease. In the testosterone-treated normal females, the oestrogen effect on vaginal smear was abolished and ovarian weight decreased, suggesting that the testosterone-mediated enhancing effect is caused by inhibition of ovarian oestrogen production. The crucial importance of oestrogens for the development of arthritis is focused on the effectiveness of treatment with gestation-related doses of E2 of normal, non-castrated females.

Animals↗
PubMed1992

Alloxan, but not streptozotocin, increases blood perfusion of pancreatic islets in rats.

It has recently been shown that selective B-cell toxins alloxan and streptozotocin (STZ) possess marked effects also on the vascular system. To evaluate to what extent changes in blood perfusion of islets induced by alloxan or STZ could be of importance for diabetogenic action of these compounds, we first investigated acute effects of alloxan (75 mg/kg body wt iv) and STZ (40 mg/kg body wt iv) on both whole pancreatic blood flow (PBF) and islet blood flow (IBF) in adult rats. Alloxan caused a marked increase in IBF, which was most pronounced 3 min after administration and remained for 30 min. PBF, however, was decreased 3 min after alloxan administration but was similar to that of control animals from 10 min and onward. These two opposite effects on IBF and PBF caused the fraction of whole PBF diverted through islets to increase from approximately 10 to 50%. Pretreatment with glucose (2 g/kg body wt iv), indomethacin (3.5 mg/kg body wt iv), dimethyl sulfoxide (10 ml/kg body wt ip of a 33% solution), superoxide dismutase (SOD, 1,000 kU/kg body wt iv), NG-methyl-L-arginine (30 mg/kg body wt iv), theophylline (7 mg/kg body wt iv), or terbutaline (1 mg/kg body wt iv) failed to affect stimulation of IBF by alloxan observed at 3 min. SOD was found to exert a marked stimulation of IBF both when given alone and together with alloxan. Alloxan increased IBF and decreased PBF also in a syngeneic pancreaticoduodenal graft in rats but did not affect flow distribution in a perfused pancreas-duodenum preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Alloxan↗
PubMed1992

Whole pancreatic blood flow and islet blood flow in hypovolemic hypotension in rats.

The blood volume of adult, male rats was reduced with 5 ml (approximately 30% of the total blood volume) by bleeding, which reduced the mean arterial blood pressure (MAP) to 50 mm Hg. This hemorrhagic hypotension caused an increase in both serum glucose and serum insulin concentrations when compared with either normotensive control animals or with rats infused with nitroprusside to obtain an MAP similar to that of the bled animals. The blood perfusion of the whole pancreas was reduced in both groups of hypotensive animals but more markedly in those with hemorrhagic hypotension. The islet blood flow was reduced only in the bled animals. The percentage fraction of blood diverted through the islet organ was markedly increased in bled rats compared to the control animals, whilst this increase was less pronounced in the nitroprusside-infused rats. The vascular conductance in the nitroprusside-treated rats was unchanged for the whole gland, but increased for the islets. Both these values in bled animals were decreased. It is concluded that the blood flow regulation differs between the endocrine and exocrine parts of the pancreas in hypovolemic hypotension.

Animals↗
PubMed1992

A continuous 48-hour glucose infusion in rats causes both an acute and a persistent redistribution of the blood flow within the pancreas.

Male Sprague-Dawley rats were infused for 48 h at a rate of 1.8 ml/h with either a 30% solution of D-glucose or a 10% solution of D-mannitol. The blood perfusion of both the whole pancreas and the islets was measured with a microsphere technique either immediately after the infusion or 10 days later. Infusion of mannitol did not influence the serum glucose or the serum insulin concentration at any time point. Infusion of glucose, however, increased both the glucose and insulin concentrations during the infusion period, but 45 min after the infusion ended both the glucose and insulin concentrations had already returned toward the values found in the mannitol-infused rats. Intraperitoneal glucose tolerance tests were normal both immediately after the infusion and 8 days later. The glucose infusion caused a significant increase in whole pancreatic blood flow and islet blood flow when compared to mannitol-infused rats immediately after the infusion. The increase in blood perfusion of the islets was more marked than that to the whole pancreas since a larger fraction of the whole pancreatic blood flow was diverted through the islets. Ten days after the infusion there was still a marked increase in the fractional islet blood flow in the glucose-infused animals, whereas the absolute flow values for whole pancreatic or islet blood flow did not differ significantly between the groups. We conclude that continuous hyperglycemia for 48 h causes an acute increase in both whole pancreatic and islet blood flow, and that a redistribution of the blood flow within the gland is present 10 days after the infusion.

Analysis of Variance↗
PubMed1992

Reinnervation of syngeneic mouse pancreatic islets transplanted into renal subcapsular space.

A syngeneic transplantation of 150 islets into the subcapsular renal space was performed on normoglycemic or alloxan-induced diabetic male C57BL/6 mice. Six, 8, 14, or 20-21 wk after transplantation, the graft-bearing kidney was removed and processed for microscopical examinations with indirect immunofluorescence for neuropeptides and tyrosine hydroxylase, and with acetylcholinesterase staining to visualize nerve fibers within the graft. Six weeks after implantation, only a few scattered nerve fibers were observed within the grafts. A progressive increase in the number of nerves was observed until 14 wk after transplantation, after which, a stable level was reached. Alloxan-induced diabetic mice showed quantitatively and qualitatively similar reinnervation to normoglycemic mice 20 wk after transplantation. The findings demonstrate the presence of sympathetic nerve fibers (containing tyrosine hydroxylase and neuropeptide Y), mainly accompanying ingrowing blood vessels; parasympathetic nerve fibers (containing acetylcholinesterase and vasoactive intestinal peptide), possibly reaching the graft from the adjacent renal capsule; and afferent nerve fibers (containing substance P and calcitonin gene-related peptide), which were less numerous. The data suggest that transplanted islets become reinnervated by ingrowth of nerve fibers from the implantation organ and that several types of nerves are present.

Animals↗
PubMed1992

Glucose tolerance and pancreatic islet blood flow in rats after intraperitoneal administration of different anesthetic drugs.

A comparison of the effects of different anesthetics on the pancreatic islet blood flow as measured with a microsphere technique and the blood sugar homeostasis in rats was made in rats anesthetized with an IP injection of either thiobutabarbital sodium (TB), pentobarbital sodium (PB), chloral hydrate (CH), chloral hydrate + pentobarbital (CP) or ketamine + xylazine (KX). The mean arterial blood pressure was similar (approximately 100 mm Hg) in all animals except those given KX in which a 20-30% increase was observed. The serum insulin concentrations were increased in rats given CH and CP, but not in the other groups, when compared with TB rats. An intraperitoneal glucose tolerance test (2 g glucose/kg BW 15 min after induction of anesthesia) showed a marked glucose intolerance in the KZ rats, in which the glucose concentrations were elevated for 5 h. Also animals anesthetized with CP and CH were glucose intolerant when compared with TB animals. The whole pancreatic blood flow was similar in TB, PB and CP rats, but was almost doubled in CH-rats and markedly decreased in KX rats. Islet blood flow was also increased by CH and decreased by KX when compared with TB rats, whilst PB and CP did not affect the islet blood flow. It is concluded that TB and PB are suitable anesthetics for the study of pancreatic islet blood flow.

Anesthetics↗