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J Tollemar

Publications and source records attributed to J Tollemar.

84 records · Page 5Linked to original sources
PubMed1987

Tissue culture of human fetal pancreas: growth hormone stimulates the formation and insulin production of islet-like cell clusters.

The human fetal pancreas (HFP) is a potential source of insulin-producing B-cells for transplantation to insulin-dependent diabetic patients. We recently described a technique for culturing HFP tissue in vitro which results in the development of islet-like cell clusters (ICC). These clusters exhibited (pro)insulin biosynthesis and a modest rate of insulin secretion, and immunocytochemical staining indicated the presence of insulin-positive cells in the cell clusters. In this study this technique was used to evaluate the effects of the addition of 1000 micrograms/L GH to HFP cultured in medium RPMI-1640 plus 10% human serum. ICCs developed in 21 of 33 consecutive cultures. GH increased the yield of ICC by 35% compared to explants supplemented with human serum alone. The insulin content of the ICCs also was increased, but the size of individual ICCs was not affected by GH, as reflected by an unchanged DNA content. GH also caused increased insulin release when the ICCs were stimulated with 16.7 mM glucose plus 5 mM theophylline. However, (pro)insulin biosynthesis was not affected by the addition of GH. These results suggest that GH stimulates the formation of both ICCs and insulin production within the explants. These observations are relevant both for the production of human fetal B-cells intended for transplantation into insulin-dependent diabetic patients and for our knowledge of the growth regulation of the HFP B-cell.

Culture Techniques↗
PubMed1987

Tissue culture of human fetal pancreas. Effects of human serum on development and endocrine function of isletlike cell clusters.

The human fetal pancreas represents a source of insulin-producing beta-cells with a potential for transplantation to diabetic patients. It has previously been shown that such cells can be viably maintained in tissue culture media containing fetal calf serum (FCS) and that these explants continue to synthesize and release insulin. In this study the effects of human serum (HS) on the growth and function of human fetal pancreatic explants have been compared with those of FCS. For this purpose, pancreatic glands, obtained after prostaglandin-induced abortions, were briefly exposed to collagenase, and the digest was cultured in RPMI-1640 medium plus 10% pooled HS or FCS. The outgrowth of isletlike cell clusters (ICCs) was monitored. In 31 of 58 consecutively explanted glands, development of ICCs was observed. In the presence of FCS the outgrowth of ICC took place on top of a fibroblast monocellular cell layer; HS effected less growth of fibroblasts and increased the formation of ICCs about sevenfold compared with explants from the same glands maintained in FCS. However, in the explant cultures with HS, the cell number per ICC, expressed as DNA content, was reduced by 50%. In both FCS and HS the insulin content of the medium showed great variability and progressively declined from day 2 to day 5. The medium glucagon concentration also decreased but not to the same extent as that of insulin. Immunocytochemical-stained ICCs showed insulin- and glucagon-positive cells scattered among most nonstained, presumably nonendocrine cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood↗
PubMed1985

Tissue culture of human fetal pancreas. Development and function of B-cells in vitro and transplantation of explants to nude mice.

The present study evaluates the development and function of human fetal B-cells in vitro with a view to using such cells in future attempts for transplantation of human fetal pancreas to diabetic patients. A method previously described in our laboratory for preparing islets in vitro from the fetal rat pancreas has been applied and modified for use with human fetal pancreas. Pancreatic glands of different gestational ages were obtained from 37 consecutive prostaglandin-induced abortions. After a mild collagenase treatment, the partially disintegrated tissue was maintained in culture for 7 days in tissue culture medium RPMI 1640 plus 20% fetal calf serum to permit cell attachment and out-growth of endocrine cells. In 17 of the 37 consecutively cultured fetal pancreatic glands, islet-like cell clusters were formed. The 20 remaining glands were lost because of either bacterial contamination or lack of viability already before dissection had occurred. Sections of the newly formed cell clusters revealed well-preserved pancreatic cells showing frequent mitotic figures. The tissue exhibited a high rate of (pro)insulin biosynthesis and a modest insulin response to secretory stimuli, suggesting that the mechanism of glucose regulation by the fetal B-cells is not yet fully developed. Electron micrographs showed a large number of granule-containing cells, some of which were identified as B-cells. In nine cases, harvested cell clusters were implanted beneath the kidney capsule of nude mice. When these animals were killed after 2 mo, seven mice showed a considerable growth of the grafts with numerous islet-like structures containing insulin- and glucagon-positive cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

A retrospective clinical comparison between antifungal treatment with liposomal amphotericin B (AmBisome) and conventional amphotericin B in transplant recipients.

Invasive fungal infections are an important cause of morbidity and mortality in immunosuppressed bone marrow and solid organ transplant recipients. Treatment with amphotericin B, the drug of choice for these infections, is however often limited by toxicity. Ten transplant patients receiving a liposomal amphotericin B formulation (AmBisome) were compared to ten retrospective control patients given conventional amphotericin B. Each group included bone marrow (8), kidney (1), and liver transplant (1) recipients. Conventional amphotericin B treatment was instituted due to nine Candida infections, and one Aspergillus fumigatus infection. In the AmBisome group treatment was instituted due to eight Candida infections, one infection caused by Saccharomyces cerevisiae and in one case as prophylactic treatment. In the amphotericin B group, maximal daily doses ranged from 0.1 to 0.65 mg kg-1 and cumulative doses were 21-836 mg kg-1 and were given over 3-32 days. In the AmBisome group, maximal daily doses ranged from 0.9 to 2.3 mg kg-1 and cumulative doses ranged from 225 to 3525 mg kg-1 over 8-28 days. All patients in the amphotericin B group experienced severe toxicity, especially nephrotoxicity which in four cases caused withdrawal of the drug. In contrast, the only adverse reaction in the AmBisome group was cholestasis in one patient. Only three out of ten patients in the amphotericin B group responded to treatment, seven patients died and six patients still had evidence of invasive fungal infection at autopsy. In contrast, eight out of nine patients in the AmBisome group responded to treatment, and the patient that received prophylaxis had a successful course.

Adolescent↗
PubMedDate not supplied

Liposomal amphotericin B (AmBisome) treatment of invasive fungal infections in immunocompromised children.

Thirteen children were treated for 16 cases of proven (8 cases) or suspected (8 cases) invasive fungal infections caused by Candida spp. (9 cases), Aspergillus spp. (3 cases) and mycetoma (1 case). The type of fungal infection was not identified in 3 cases. Liposomal amphotericin B (AmBisome) was instituted because of the failure of previous treatments in 9 cases, toxicity-associated amphotericin B therapy in 4 cases and renal insufficiency in 3 cases. AmBisome was given for a median of 19 days (range 3-55) with a mean cumulative dose of 1.8 +/- 1.3 g (+/- SD). Acute toxic side-effects were not seen in any patients. Slight increases in serum creatinine were seen in 3 cases during AmBisome therapy. No other side-effects were observed. Among 8 cases with proven invasive fungal infection, 6 were clinically cured, one had persistent fungi and one died after only 3 days of AmBisome therapy. Eradication of fungi was documented in 5 out of 6 cases. Among the 8 cases with presumed fungal infections, 6 were clinically cured, one improved and one died after 6 days of treatment. To conclude, AmBisome can safely be given to children with invasive fungal infections; side-effects are minimal and among those treated for at least a week, the overall cure rate was 86% (12 out of 14).

Adolescent↗
PubMedDate not supplied

Antibody response to Candida and its use in clinical practice.

Reference values for specific IgM, IgA and IgG antibodies against three defined Candida antigens were determined in 280 healthy Swedish children aged 1 month to 15 years. The antibody response in 10 children with Candida infections was also determined. Precipitating IgG antibodies to a mannan-free Candida protein antigen were detected only in children with Candida infection. The haemagglutinating IgM antibody response in healthy children to a polysaccharide Candida antigen was weak. Adult levels of < or = 320 (95% confidence interval, CI) were not reached even in the oldest children (< or = 160). All children with Candida infections had elevated IgM titres. Adult levels of IgA antibodies to Candida mannan were reached at 10-12 years of age; at 13-15 years the titres were higher (< or = 1600) than in healthy adults (< or = 1000, 95% CI). All children with an acute Candida infection had elevated IgA titres. Our study shows that antibody testing may be used to diagnose systemic Candida infection in children and to follow the progression and resolution of systemic Candida infection with the rise and fall of antibody titres.

Adolescent↗
PubMedDate not supplied

Safety and efficacy of liposomal amphotericin B in allogeneic bone marrow transplant recipients.

In a retrospective analysis, 79 allogeneic bone marrow recipients treated with AmBisome prophylactically or because of proven or suspected invasive fungal infection (IFI) were evaluated in 92 episodes. The median duration of treatment was 14 (range 1-112) days. The mean maximum dose given was 1.64 +/- 0.8 mg kg-1 day-1 and the mean total dose was 1.29 +/- 2.28 g. The overall incidence of reported adverse events was 194, of which none had a serious outcome. In six cases, the drug was withdrawn as a result of toxic or allergic reactions: dyspnoea and flush (3), urticaria (1), cholecystitis (1) and disorientation (one case, probably not related to AmBisome). No anaphylactoid reactions were seen. Laboratory findings, including low serum potassium (48% of the episodes), increased serum creatinine (38%) and increased serum sodium levels (7%), caused no major clinical problems. Thirteen cases of verified IFI were evaluated regarding the efficacy of AmBisome. Survival or cure of the mycotic infection occurred in 5/13 patients (38%). Two patients were treated with AmBisome (3.6 and 3.3 mg kg-1 day-1) because of verified IFI before BMT. One died of IFI. The other died of venoocclusive disease of the liver (VOD) without histological evidence of active IFI. We found a significant (P < 0.05) reduction in autopsy-proven IFI, 12/199 (6%) compared to the period when only conventional doses of amphotericin B were used, 26/227 (11%).

Adolescent↗
PubMedDate not supplied

Experimental pancreatic transplantation in diabetes.

Although transplantations of vascularized pancreas in diabetic patients show steadily improving results, the immediate operative risks and life-long immunosuppressive medication involved represent considerable disadvantages. Efforts are being made to develop simpler and safer methods of transplantation with isolated pancreatic islet grafts, e.g., isolated islets, fetal pancreas, or dispersed adult pancreas. Iso-, allo-, and xenografts of such preparations have been shown to reverse diabetes in animals. However, attempts to apply these techniques in clinical practice have remained largely unsuccessful, and major technical advances are needed before success is achieved. Attempts to use whole, segmented, or isolated islets from pancreatic grafts as a cure for diabetes in animals and in diabetic patients are reviewed. The importance to the graft's permanent function, of adequate preparation and storage of the graft, and of beta-cell growth and vascularization are reviewed. Various forms of immunomodulation by pretreatment of grafts in vitro have been employed in animal models of diabetes, but none of these have yet been employed with long-term success in humans. Recurrence of a specific autoimmune response toward the beta-cell in a spontaneously diabetic recipient is a potential mechanism for destruction of transplanted islet tissue.

Animals↗