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Biomedical subjects

C Laue

Publications and source records attributed to C Laue.

At least 19 recordsLinked to original sources
PubMed2001

Improved yield and functionality of parathyroid cells separated by using collagenase-digestion with cold pre-incubation.

Preparation of cells from solid organs often induces a functional impairment due to the proteolytic cell damage by the applied digestive enzyme like collagenase, trypsin or dispase. To preserve the tissue and to enhance the yield of cells, Laue et al. reported an islet cell isolation with pre-incubation at 4 C permitting the enzyme to diffuse into the tissue and explicite activity equally throughout the whole particle. The aim of this study was to investigate whether this procedure can be applied to parathyroid glands. Therefore porcine parathyroid glands were dissected into 1 mm3 pieces. Subsequently one group of these pieces was incubated 22 h at 4 C in 2 mg/ml collagenase before activating the enzyme by elevating the temperature to 37 C for 30 min. The other group was incubated directly at 37 C for 30 min. The yield of cells and their viability was assessed by light-microscopy and staining with trypan-blue. After the cells were immobilized in barium-alginate and cultivated for 7 days, the function was tested by incubation in different calcium concentrations and PTH-measurement. Finally, the viability was assessed by histology. Using a cold pre-incubation with collagenase, a significantly higher number of isolated cells was retrieved compared with collagenase-digestion without pre-incubation. The viability was about 100% and did not differ between both groups. After immobilization and cultivation the viability decreased to less than 30%, with and without pre-incubation. In contrast to viability the PTH-secretion of the cells differed significantly between both procedures. By pre-incubation with collagenase at 4 C a gentle method is presented resulting in an enhancement of yield and function of single cells of parathyroid glands.

Animals↗
PubMed2001

Effect of extracellular pH on insulin secretion and glucose metabolism in neonatal and adult rat pancreatic islets.

Changes in extracellular pH are known to affect glucose-stimulated insulin secretion. In the present study, glucose metabolism in pancreatic islets cultured at different pHs was investigated. Also, for islet transplantation purposes, insulin secretion and glucose metabolism were compared in neonatal and adult islets at different pHs to determine which islet preparation is more tolerant to acidity and alkalinity. The results revealed a dependency of insulin secretion on the external pH in both neonatal and adult islets. Reduction of insulin secretion was observed at both the acidic and alkaline sides of pH 7.3. Glucose stimulated increases of insulin secretion in all cases. Similar results were obtained for ATP and pyruvate contents. Intracellular insulin increased with the increase of pH value. In contrast, calcium content decreased with the increase of pH. The results demonstrate that neonatal islets are more acid tolerant than adult islets. Both basal and glucose-stimulated insulin secretions, as well as other parameters of neonatal islets were significantly higher than those of adult islets in response to low pH. The differences under alkaline conditions were not significant but give an indication that neonatal islets are more tolerant to alkalinity than are adult islets.

Adenosine Triphosphate↗
PubMed2001

Xenotransplantation of parathyroids in rats using barium-alginate and polyacrylic acid multilayer microcapsules.

The integrity and function of encapsulated parathyroid tissue following xenotransplantation is limited by oxygen and nutrition supply and capsule fibrosis. Since some of these factors depend on stability and biocompatibility of the coating material, multilayer microcapsules have been developed. Parathyroid tissue pieces and digested single cells from pigs were encapsulated in barium-alginate and in polyacrylic acid (PAA) multilayer capsules. After 7 days of culture the function of the encapsulated cells were assessed. Subsequently, in a part of the cultured microcapsules the viability was directly assessed whereas the other part was transplanted in dark animal [DA] rats for 30 days. After explantation viability and fibrotic reaction were examined. Single cells showed a significant increase in parathyroid hormone [PTH] secretion when exposed to medium low in calcium, whereas minced tissue pieces revealed necrosis without stimulatory responsiveness. Morphometry showed significantly better viability of single cells compared with minced tissue in vitro and in vivo. The fibrotic reaction against capsules with minced tissue was more pronounced than for capsules containing single cells. There was no difference between barium alginate and PAA capsules when containing minced tissue. In single cells, however, the fibrous tissue reaction differed significantly between barium alginate and PAA capsules. Encapsulated single cells of parathyroid tissue maintain detectable function and viability. In contrast minced tissue underwent necrosis and induced significantly more connective tissue reaction than single cells indicating an interrelationship between necrosis and fibrosis.

Acrylic Resins↗
PubMed2001

Probiotics--compensation for lactase insufficiency.

Yogurt and other conventional starter cultures and probiotic bacteria in fermented and unfermented milk products improve lactose digestion and eliminate symptoms of intolerance in lactose maldigesters. These beneficial effects are due to microbial beta-galactosidase in the (fermented) milk product, delayed gastrointestinal transit, positive effects on intestinal functions and colonic microflora, and reduced sensitivity to symptoms. Intact bacterial cell walls, which act as a mechanical protection of lactase during gastric transit, and the release of the enzyme into the small intestine are determinants of efficiency. There is a poor correlation between lactose maldigestion and intolerance; in some studies, low hydrogen exhalation without significant improvement of clinical symptoms was observed. Probiotic bacteria, which by definition target the colon, normally promote lactose digestion in the small intestine less efficiently than do yogurt cultures. They may, however, alleviate clinical symptoms brought about by undigested lactose or other reasons.

Animals↗
PubMed2000

Effect of media composition on long-term in vitro stability of barium alginate and polyacrylic acid multilayer microcapsules.

For a number of applications stability of microcapsules is a critical factor. Since the maintenance of polyelectrolyte complexes depends considerably on the ion composition we tested the physical properties of barium alginate capsules and searched for conditions to improve stability by a multilayer coating with polyethylenimine (PEI) and polyacrylic acid (PAA). Mechanical stability and diameters were determined in barium alginate capsules and compared with multilayer capsules. Multilayer coating resulted in smaller capsules than barium complexing alone. The difference was more pronounced when CaCl2 was used instead of NaCl during coating. Barium alginate capsules and application of CaCl2 during coating led to continuous pressure profiles, whereas NaCl resulted in bursting at a defined pressure, indicating the additional contribution to mechanical stability by the outer layers. After 7 d culture, mechanical stability of coated capsules decreased in RPMI and NaCl but was most pronounced in sodium citrate. The capsule diameter increased in sodium citrate, less pronounced in NaCl and was significantly different to RPMI and double distilled water. During long-term culture in RPMI, the diameter increased and mechanical stability decreased significantly. Multilayer coating improved mechanical stability which was impeded most in sodium citrate, to a lesser extent by NaCl and RPMI even after long-term exposure.

Acrylic Resins↗
PubMed1999

The effect of alginate and hyaluronate on the viability and function of immunoisolated neonatal rat islets.

Recent observations suggest that the extracellular matrix plays a role as regards the viability and morphological integrity in long-term culture of Langerhans islets. For the present study we encapsulated neonatal rat islets without extracellular matrix (WEM), with alginate solution (AL) and with hyaluronate solution (HY) into cuprophane hollow fibers. Function was tested after week 1 and 5. The insulin release of WEM encapsulated islets decreased significantly during the culture period. In contrast to this, AL and HY embedded islets had stable secretion values throughout the whole cultivation. Histological examination confirmed that viability of HY and of AL embedded islets differed significantly from that of WEM encapsulated islets. Furthermore, HY seems to be a more advantageous environment to immunoisolated islets than AL. Both the insulin secretion values and the viability of HY embedded islets were higher than of AL embedded islets. We conclude that an extracellular matrix is important for immunoisolated islets, to maintain their function and morphological integrity and that HY is especially suitable for this application.

Alginates↗
PubMed1993

The phenomenon of a high triglyceride response to an oral lipid load in healthy subjects and its link to the metabolic syndrome.

Excessive postprandial triglyceride (TG) responses despite normal fasting TG levels have been described in single cases within small groups of healthy subjects and in patients with obesity or precocious atherosclerosis, known to be associated with high insulin fasting levels. To clarify this association, fasting and postprandial TG and insulin levels were studied in 113 healthy young (25.7 +/- 2.6 years), normal weight (body mass index 20.8 +/- 2.3 kg/m2) male subjects who were selected from among 117 subjects on the basis of TG fasting levels < 200 mg/dl. After a 12-hour fast a standardized liquid lipid load was administered containing 58 g mainly saturated fat and 1,017 kcal energy. Both fasting TG values and postprandial TG peak values showed bimodal frequency distributions. Statistical analysis of fasting TG discriminated two groups: a low fasting TG group with normally distributed values < 150 mg/dl (mean +/- SEM: 79.5 +/- 2.7 mg/dl; n = 104) and a high fasting TG group > 150 mg/dl (194.5 +/- 7.2 mg/dl; n = 13). Likewise, two groups could be differentiated according to their maximal postprandial TG response (TG max) to the lipid load: (1) normal responders with TG max < 260 mg/dl (mean +/- SEM: 123 +/- 4.8 mg/dl; n = 96) and (2) high responders with TG max > 260 mg/dl (272.5 +/- 20.5 mg/dl; n = 17). Fasting TG and TG max were highly correlated (r = 0.745; p < 0.0001). However, 9 of 17 (53%) high responders had fasting TG < 150 mg/dl, which means that the prediction of high response is only 47.0% based on fasting TG values. Fasting insulin levels were significantly higher in high responders than in normal responders, whereas they did not differ between the low and high fasting TG group. In conclusion, the bimodal frequency distribution of TG max after a lipid load permitted the differentiation of two groups, normal responders and high responders, with higher fasting insulin levels, which might indicate a link to the metabolic syndrome.

Adult↗
PubMed1993

Long-term function of porcine islets and single cells embedded in barium-alginate matrix.

The influence of alginate-embedding on the maintenance of functioning and morphological integrity in long-term culture of isolated porcine islets and islet cells was studied. Free-floating islets and islet cells served for control. Function was tested after the 1st, 2nd and 4th week. Basal and glucose-stimulated insulin secretion of embedded islets decreased slightly, but significantly after the first week (from 4.39 +/- 0.64 to 2.87 +/- 0.47 at normal and from 11.96 +/- 1.44 to 4.76 +/- 0.78 microU pro 24 h pro islet at elevated glucose concentration, p < 0.05 and < 0.01, resp.) and remained unchanged thereafter. Glucose-stimulation resulted in significant increases in insulin secretion at all three testings (p < 0.001, < 0.01 and < 0.01). Single cells in alginate matrix had even more stable insulin secretion throughout the whole cultivation with significant increases to glucose challenge (p < 0.01, < 0.01 and < 0.05). In contrast, insulin secretion of free-floating islet cells decreased from 5.70 +/- 1.19 to 2.04 +/- 0.64 and to 1.05 +/- 0.33 at basal conditions (p < 0.01 and < 0.05) and from 11.39 +/- 1.87 to 2.76 +/- 0.76 and to 2.15 +/- 0.71 microU pro 24 h pro islet under stimulation (p < 0.01 and not sign). In addition, the secretory response to glucose challenge was significant only at the first testing (p < 0.05). Non-embedded islets could be tested only at the first week since after this time they dissociated to single cells. Embedded islets and single cells showed intact morphology after four weeks with trypan blue (TPB) positivity of less than 5%.(ABSTRACT TRUNCATED AT 250 WORDS)

Alginates↗