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Biomedical subjects

L Kerp

Publications and source records attributed to L Kerp.

At least 19 recordsLinked to original sources
PubMed1993

In vivo labelling of the spleen with a red-fluorescent cell dye.

A method for labelling mouse spleen cells in situ is described. Spleen vessels were clamped before intrasplenic injection of a red-fluorescent cell dye (PKH-26). The labelling rate was 11.8% of all cells and 13.9% of B lymphocytes 30 min after injection as determined by FACS. 3 days later, the proportions of labelled cells were reduced to 7.4% (P < 0.01) and to 10.7% (P < 0.05), respectively. Only 10% of cells detected by FACS could be detected by fluorescence microscopy. Labelled cells were not found in peripheral lymph nodes 30 min after spleen injection, but were present 3 days later (FACS: 2.8% of all cells and 5.4% of B lymphocytes, P < 0.05 each), indicating migration of stained cells. Neither adverse nor toxic effects of in situ staining were observed. Isolated stained B lymphocytes from spleens of naive mice and from lymph nodes after immunisation with insulin showed proper function when tested in an ELISA-spot assay. The labelling procedure was used to follow splenic B lymphocytes producing natural anti-insulin antibody. These cells were found to be recruited for the early immune response in lymph nodes immunised with insulin.

Animals↗
PubMed1993

[Pulsatile insulin secretion into the portal vein in liver cirrhosis].

To characterize the pulsatile liberation of pancreatic hormones, blood was taken from the portal vein of four patients (three men, one woman; aged 65-71 years) with alcoholic (n = 3) or posthepatitic (n = 1) liver cirrhosis. The concentrations of glucose, insulin, C-peptide and glucagon were measured within one minute. The concentrations of insulin, C-peptide and glucagon varied considerably in intervals of 4.1-6.5 min. The swings in insulin concentration ranged between 17 and 163.5 microU/ml. Oral glucose loading with 100 g increased the insulin and C-peptide swings, but not their periodicity. This indicates that pulsatile insulin secretion is amplitude not rate driven.

Aged↗
PubMed1993

A time-resolved fluoroimmunoassay for human insulin based on two monoclonal antibodies.

The insulin time-resolved fluoroimmunoassay (TRFIA) described here is a 'sandwich type' immunoassay using two monoclonal antibodies recognizing different epitopes of insulin. One of the antibodies is fixed to a solid phase and the other is biotinylated. After sandwich formation the biotinylated antibody is detected by time-resolved fluorometry with the fluorophore europium which is coupled to streptavidin. Serum samples of 100 microliters can be analyzed within a concentration range of 4 microIU/ml up to 500 microIU/ml. The detection limit of this assay, 3.9 microIU/ml, is comparable to the conventional radioimmunoassay and the results overall correlate well with those of the radioimmunoassay (r = 0.99). There is no detectable crossreaction with human proinsulin even using a proinsulin concentration of 2000 microIU/ml. The assay is performed with the DELFIA system (Pharmacia).

Animals↗
PubMed1993

Glucose-induced water movement from the intracellular to the extracellular space and its influence on calculations of glucose metabolism.

The osmotic effect of intravenous glucose was investigated in eight healthy volunteers. Increases in plasma glucose can induce water movement from the intracellular to the extracellular space. Serum choline esterase was used as an endogenous marker of serum dilution. Intravenous tests with 5, 15, 30 and 35 g of glucose showed that the water shift was proportional to the amount infused. The respective dilutions of choline esterase were 1.3 +/- 0.7%, 3.3 +/- 0.9%, 6.3 +/- 0.8% and 7.8 +/- 0.5%. The effect on extracellular water was maintained when plasma glucose remained elevated (inhibition of insulin secretion with a somatostatin analogue). In comparison to glucose, infusion of 10 g of a mixture of amino acids produced a less pronounced effect than expected. The acute water shift after intravenous glucose dilutes serum components including glucose (8% of total extracellular glucose at 35 g). This can be misinterpreted as glucose clearance when calculating metabolic rates. For estimated amounts a proportional correction should be made (3.5% per 5 mmol l-1 increase). A measured plasma glucose of 22.2 mmol l-1 should be corrected to 24.8 mmol l-1, while a plasma glucose value of 5.0 mmol l-1 needs no correction.

Blood Glucose↗
PubMed1993

Influence of 6-week, 6 days per week, training on pituitary function in recreational athletes.

The influence on pituitary function of 6 weeks of training on 6 days a week was examined in six recreational athletes. Endurance training on a bicycle ergometer for 31-33 min was performed on 4 days each week at 90-96% (weeks 1-3) and 89-92% (weeks 4-6) of the 4 mmol lactate thresholds determined on day 0 and day 21, respectively, with interval training of 3-5 x 3-5 min in addition on 2 days a week at 117-127% and 115-110%, respectively. Determination of the serum hormone levels and a combined pituitary function test (200 micrograms thyrotropin releasing hormone (TRH), 100 micrograms gonadotrophin-releasing hormone (GnRH), 100 micrograms corticotrophin releasing hormone (CRH), 50 micrograms growth hormone releasing hormone (GHRH)) were made before training, after 6 weeks of training and after another 3 weeks of recovery. Training increased performance at 2 mmol lactate by 25%, at 4 mmol by 12%, and maximum performance by approximately 12%. The releasing hormone-stimulable prolactin, thyroid stimulating hormone (TSH) and somatotrophic hormone (STH) synthesis-secretion capacity remained unchanged, the adrenocorticotrophic hormone (ACTH) was increased after training. Cortisol release was reduced, follicle-stimulating hormone (FSH)-synthesis-secretion capacity was increased after training, and the luteinizing hormone (LH)-synthesis-secretion capacity reduced. This had no influence on base or exercise-induced serum hormone levels (cortisol, aldosterone, insulin, prolactin, FSH, LH, TSH, ACTH, ADH and STH), which showed no dependence on training, except for free testosterone which showed a decreasing trend (P < 0.10) of 19-25% and post-exercise ACTH which showed an increasing trend of 33% (P < 0.10). Conditioning (cortisol sensitivity and ACTH response) or adaptation (FSH and LH responses) to changed testosterone serum levels and altered spermatogenesis is discussed.

Adrenocorticotropic Hormone↗
PubMed1992

Is the reuse of needles for insulin injection systems associated with a higher risk of cutaneous complications?

Twenty diabetic patients participated in a study to assess if multiple use of needles for insulin injection systems (Pens) is safe under normal daily conditions. The previous mean duration of Pen therapy was 16.3 months. During this time, the 20 patients carried out altogether more than 33,000 injections without any sign of local infection despite needle reuse. Patients were told to use needles if possible for 1, 3, 6, 9, and 12 injections before bacteriological assessment. Bacteriological investigation of these needles showed no contamination, except with one needle used three times, which was colonized with coagulase negative Staphylococcus. In contrast, half of the needles' plastic ground points which touched the skin were contaminated. No signs of infection were observed at the injection sites throughout the study. We conclude that, based on the bacteriostatic effects of commercially formulated insulin and on the siliconisation of needles' surfaces, bacterial growth is sufficiently prevented. Therefore, we can recommend the reuse of pen needles as a simple, safe and cost-beneficial procedure.

Adult↗
PubMed1992

Osmotic stress due to changes in plasma glucose and its regulation in IDDM patients.

Intravenous glucose tolerance tests (30 g, 5 min, constant rate) were performed in 8 IDDM patients and in 8 controls. The consequences of the osmotic pressure, induced by glucose, were investigated. Serum choline esterase was used as an endogenous marker of serum dilution. Five minutes after the end of infusion plasma glucose was raised by 182 +/- 12 mg.dl-1 in patients and by 189 +/- 6 mg.dl-1 in controls. Choline esterase values decreased by 6.6 +/- 0.8% and 6.3 +/- 1.0% respectively, P less than 0.01 each. Calculated water shifts into the extracellular space were 924 +/- 112 ml and 882 +/- 140 ml respectively. Fifteen minutes after the end of infusion glucose decreased by 32 +/- 1 mg.dl-1 in IDDM patients and by 57 +/- 2 mg-1 in controls. Serum choline esterase recovered by 2.6 +/- 0.2% and 2.7 +/- 0.2% respectively, P less than 0.01 each, indicating comparable water correction in spite of the slower fall of glucose in IDDM patients. Water correction was more rapid than glucose fall. Diuresis (46 +/- 4 ml versus 42 +/- 3 ml) or cellular uptake of serum solutes (electrolytes, amino acids, urea, creatinine) could not explain this. It is hypothesized that accumulation of free intracellular glucose reduces the osmotic gradient and facilitates cellular water re-uptake.

Adult↗
PubMed1992

The pupillary light reflex. 1. Age-dependent and age-independent parameters in normal subjects.

A hundred and three normal subjects (14-75 years old) were examined with a modified infrared TV videopupillometer that had previously been developed. Maximal pupillary diameter (p less than 0.00001), pupillary diameter in percent of iris diameter (p less than 0.00001), maximal pupillary area (p less than 0.00001), latency time of the light reflex (p less than 0.00001), maximal contraction velocity (p less than 0.00002), contraction velocity at 1 s (p less than 0.00001) and dilatation velocity at 6 s (p less than 0.0001) are strongly age dependent. A statistical formula is given to allow the calculation of the exact percentile for every parameter. Parameters which are age independent if they are expressed in percent of the maximal pupillary area are contraction velocity at 1 s (r = 0.042, p = 0.68) and dilatation velocity at 6 s (r = -0.150, p = 0.13). They can be used if age-matched study groups are not available. Furthermore, it is shown that most parameters of the pupillary light reflex correlate significantly with each other. The highest correlations are found with the maximal pupillary area. Differences between sexes are not evident. It is thought that this infrared videopupillometry and the given data base are useful for further clinical studies to investigate the autonomic nervous system.

Adolescent↗
PubMed1992

The pupillary light reflex. 2. Prevalence of pupillary autonomic neuropathy in diabetics using age-dependent and age-independent pupillary parameters.

Seventy-seven diabetics with a duration of the disease ranging from 2 to 55 years (average 18.5 years) were studied with infrared videopupillometry. The prevalence of diabetic autonomic neuropathy at the pupillary control system (pANP) was studied comparatively using several pupillary tests. The average prevalence using age-dependent parameters was 30.2% [maximal pupillary area: 22.1%, maximal contraction velocity: 24.7%, contraction velocity at 1 s (CV1): 28.6%, and dilation velocity at 6 s (DV6): 45.5%]. Comparing these percentages to prevalences of other diabetic late complications, e.g. retinopathy (49.4%), DV6 seems to be good for the diagnosis of pANP. If CV1 and DV6 are expressed in percent of the maximal pupillary area (CV1% and DV6%), they become age-independent. The average CV1% and DV6% of diabetics differ highly significantly from those of normals (CV1%: 58.6 +/- 14.5 vs. 64.1 +/- 6.4%, 2 p less than 0.005, and DV6%: 6.0 +/- 2.9 vs. 7.3 +/- 1.1%, 2 p less than 0.001). The average prevalence of pANP using these age-independent parameters was 25.4%. These data suggest that the prevalence of pANP, especially disorders of pupillary dilation (DV6), is high in long-standing diabetes. Furthermore, CV1% and DV6% have proved to be valid parameters in finding differences in the light reflex in non-age-matched study groups.

Adolescent↗
PubMed1991

Lack of beta 2-adrenoceptor induced long-acting effect on glucose tolerance in type 2 diabetic patients.

The long-acting effect of a 10-min pulse infusion of the beta 2-adrenergic agonist fenoterol on oral glucose tolerance tests in controls and in normotensive patients with type 2 diabetes mellitus on diet was compared. During an oral glucose load starting 2 h after fenoterol control persons showed hyperglycemia (area: 25,950 +/- 467 vs. 22,650 +/- 410, P less than 0.01), hyperinsulinemia (area: 13,980 +/- 1050 vs. 8160 +/- 405, P less than 0.02) and a pronounced fall of serum potassium (area: 775 +/- 26 vs. 748 +/- 25, P less than 0.02). The patient group showed no late response to fenoterol: plasma glucose (area: 51,000 +/- 382 vs. 51,300 +/- 413, n.s.), serum insulin (area: 7215 +/- 233 vs. 8280 +/- 410, n.s.), serum potassium (area: 748 +/- 26 vs. 750 +/- 24, n.s.). The data show that there is a defect of the beta 2-adrenergic long-acting effect on glucose metabolism and on insulin release in type 2 diabetes mellitus.

Adult↗
PubMed1991

Urine screening in outdoor volunteers: day versus night versus 24 hour collection.

Urine constituents were measured in 12 healthy outdoor volunteers on four occasions within a month. Day, night, and 24 hour collection periods were compared. Measurements made on the four occasions did not differ. The amount of water, creatinine, electrolytes, proteins, and enzymes were higher during the day (up to three fold, p always less than 0.05), while equal amounts of amino acids were excreted in the day and the night period. A comparison of all values from all individuals for all four sampling occasions showed that the variation was lowest in the 24 hour samples. Relating the values to creatinine did not consistently reduce the variation. Twenty-four hour samples correlated better with the day than with the night samples. Day and night samples did not correlate. Twenty-four hour collection is superior to day or night collection in healthy outdoor volunteers. Based on the normal variation of values found in the present study, criteria for suspected kidney damage and therefore for the withdrawal of drugs in pharmacological studies can be defined for each collection period.

Adult↗
PubMed1990

["Lupus anticoagulant" in immune hyperthyroidism].

A 56-year-old woman with autoimmune hyperthyroidism (Basedow) whose blood coagulation had at first been normal developed prolonged partial thromboplastin time (PTT) of 48 s and a fall in prothrombin time (Quick value) to 52%. At the same time, total activity of factor VIII was reduced to 18% and factor IX to 16%. These values not having changed after the addition of normal plasma, it is assumed that an acquired inhibitor of plasmatic coagulation was responsible. Such inhibitors were first described in lupus erythematodes and therefore called lupus anticoagulant, but later also demonstrated in other autoimmune diseases.

Autoantibodies↗
PubMed1990

The detection of single cells forming antibodies to defined epitopes on insulin.

A solid-phase immunoenzymatic technique was modified to permit the detection and enumeration of antibody-secreting cells recognizing the amino or carboxy terminal of the insulin B chain. The procedure involves coating well surfaces with avidin and binding insulins specifically labelled with biotin at the B1 or B30 residue. On day 15 after immunization with human insulin, 20 outbred NMRI mice had generated cells secreting anti-insulin antibodies. The recognition of B1- or B30-related epitopes differed between individuals, suggesting that there was genetic determination of the epitopes expressed early in the immune response. The method can be used to find strains of mice with a preferential immune response to defined areas on the surface of small peptide molecules. Such strains could then be used to produce specific monoclonal antibodies.

Animals↗
PubMed1989

IgE antibodies to insulin and related peptides, a result of insulin treatment?

Anti-insulin immunoglobulin E (IgE) antibodies in sera of insulin-treated diabetic patients were characterized by affinity and concentration, and by binding to proinsulin and insulin A and B chains. The affinities of IgE to insulin scattered between less than 10(7) and 0.6 x 10(9) l/mol, the concentrations between 0.3 and 3.5 ng/ml. All positive sera of type 1 and few of type 2 patients recognized proinsulin, A chain, and B chain with comparable affinities and concentrations. Elevated concentrations of total serum IgE in 12 of the 16 anti-insulin IgE-positive sera from insulin-treated patients indicate that these patients are predisposed to allergies. The incidence of elevated levels of total serum IgE in type 1 (17.7%) and in type 2 (7.8%) diabetic patients did not differ from the general population. Reagins to insulin and related antigens were also observed in sera of non-diabetic allergic persons without previous contact with exogenous insulin. The natural occurrence of insulin-specific reagins makes the use of IgE as a marker of antigenicity of insulin questionable. Discrepancies between the insulin-positive radioallergosorbent test (RAST) or skin test and clinical manifestations of insulin allergy exist, because IgE antibodies with low affinities require high concentrations of insulin for binding. Such amounts of insulin may occur at the injection site, but not in the circulation.

Diabetes Mellitus, Type 1↗
PubMed1989

Evaluation of a solid-phase monoclonal antibody-based enzyme immunoassay for insulin in human serum.

A 'sandwich-type' enzyme immunoassay for the measurement of serum insulin is described in which a monoclonal antibody-alkaline phosphatase conjugate and an antibody-immobilized polystyrene solid phase are used. Serum samples of 50 microliters can be analyzed and the enzyme immunoassay is as sensitive as the conventional radioimmunoassay for insulin. The results obtained with ELISA correlate well with those of the radioimmunoassay (r = 0.9844) and the between-assay and within-assay coefficients of variation are less than 15% over the useful ranges of the assay (2-200 microIU/ml). The sensitivity is 2 microIU/ml and this can be increased by longer incubation times. The crossreaction with porcine insulin is 45%, with bovine insulin 30% and with human proinsulin 20%.

Animals↗
PubMed1989

Insulin abuse in long-standing IDDM.

Two patients with insulin-dependent diabetes mellitus (IDDM) for 42 and 46 years respectively were diagnosed to produce factitious hypoglycemia. They had several properties in common: abnormal personality, refusal to stop incipient hypoglycemia, ideal body weight, good hemoglobin A1c (HbA1c) values, non-specific changes in the EEG, and brain atrophy sparing the periventricular areas. The addiction forced the patients to continue their habit during hospital stay. The dose of surreptitiously injected regular insulin always produced serum insulin concentrations large enough to clarify the diagnosis.

Aged↗
PubMed1989

Gamma irradiation as a substitute for H2O2 in peroxidase-labelled enzyme immunoassays.

The ability of gamma irradiation to substitute for H2O2 in peroxidase-labelled enzyme immunoassays was investigated. Colouring of TMB (3,3',5,5'-tetramethylbenzidine), ABTS [2,2'-azino-di(3-ethylbenzthiazoline-6-sulphonic acid)], and OPD (o-phenylenediamine) was produced with doses of 10 and 20 Gy. Addition of superoxide dismutase enhanced TMB and ABTS, and inhibited OPD. The reaction was terminated when the irradiation was stopped. The use of denaturing compounds to stop the reaction was unnecessary and coated antigens could be re-used for a second immunoassay.

Free Radicals↗