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Biomedical subjects

H B Mortensen

Publications and source records attributed to H B Mortensen.

At least 37 records · Page 2Linked to original sources
PubMed1994

[A comparison of 2 new rapid methods for determination of HbA1C concentration in patients with diabetes mellitus].

We have evaluated a new immunoturbidimetric assay (DCA 2000 HbA1c system, Bayer, Denmark) for determination of HbA1c. The aim of the study was to evaluate accuracy, precision and feasibility for the DCA 2000 method when employed in a diabetes centre by a technical assistant and at a general practitioner's by non lab staff. The results were compared with a high performance liquid chromatographic method (HPLC, AUTO A1C, Kyoto Daiichi Kagaku Co., Kyoto, Japan) which is the current laboratory method, and therefore used as reference. Assay time for the DCA 2000 method was nine minutes, while the HbA1c result was displayed within four minutes by HPLC. Blood samples were drawn after informed consent from 118 patients during a period of two months at the out-patient clinic of the Dept. of Paediatrics, Glostrup Hospital (n = 67) and at a general practitioner's (n = 51). Each sample was analyzed twice by each method on two consecutive days. In the HbA1c range from four to 14% (n = 67) the average within-assay precision (SD) for the HPLC method was 0.13%, whilst it was 0.23% for the DCA 2000 method (p < 0.001). The within-assay precision was low and acceptable, and for both methods it was independent of the current HbA1c concentration. For the DCA method precision was almost similar (p > 0.07) when carried out by a technical assistant (SD: 0.20%) and by non lab staff (SD: 0.25%). Interbatch variations for HbA1c results investigated with two different batches of reagents within a month were SD 0.30% (HbA1c range: 4.9-5.9%, n = 30) and SD 0.44% (HbA1c range: 10.5-12.1%, n = 30) for these two preparations.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, High Pressure Liquid↗
PubMed1994

Elevated vibration perception threshold in young patients with type 1 diabetes in comparison to non-diabetic children and adolescents.

The vibration perception threshold (VPT) was investigated by biothesiometry in 61 children (28 boys) with Type 1 diabetes, mean age 15.5 (range 10-21) years, duration of diabetes 6.9 (range 1-19) years, and in 76 healthy children (39 males), mean age 13.8 (range 10-19) years. The measurements were performed in triplicate on the right second finger and on the right first toe. The vibration perception threshold was significantly increased (p < 0.0001) in the young diabetic patients (mean +/- SD, finger 4.1 +/- 1.1 V, toe: 5.7 +/- 1.3 V) compared to healthy children (finger 3.4 +/- 0.9 V, toe: 3.6 +/- 1.3 V). Twenty percent of adolescents with Type 1 diabetes had a VPT above the 95th percentiles (finger: 5 V, toe 6.5 V) for normal control children. In healthy controls a significant correlation (r = 0.27, p < 0.01) was found for VPT in finger versus toe. This relationship was not significant in the diabetic group and may be due to reduced sensitivity of the fingertips caused by frequent blood glucose testing. Age, Tanner stage and height were significantly correlated to VPT (toe) in both diabetic and normal boys, while duration of diabetes, HbA1c, arterial blood-pressure and body mass index were not significantly associated with VPT in any of the groups. The results indicate that changes in VPT appears early in childhood and emphasize a need for further studies of subclinical neuropathy in young patients with Type 1 diabetes.

Adolescent↗
PubMed1994

Relationship between blood pressure and urinary albumin excretion rate in young Danish type 1 diabetic patients: comparison to non-diabetic children. Danish Study Group of Diabetes in Childhood.

In 1989 a nation-wide investigation of blood pressure and urinary albumin excretion rate (AER) was carried out in 506 boys and 441 girls with Type 1 diabetes (approximately 80% of total) treated at 22 paediatric departments. In addition a reference population from 1979 consisting of 663 healthy non-diabetic children (334 boys, 329 girls) served as a control group with respect to blood pressure and body mass index. Microalbuminuria was defined as AER of 20-150 micrograms min-1 in at least two out of three timed overnight urine collections and was diagnosed in 30 adolescents (16 boys, 14 girls). Five patients (3 boys, 2 girls) had overt proteinuria (AER: > 150 micrograms min-1). Age-related percentile charts based on one blood pressure reading were provided for normoalbuminuric diabetic patients and the healthy control group. The study revealed an increase in arterial blood pressure during the period of the pubertal growth spurt for the diabetic and non-diabetic group. The changes were most pronounced for systolic blood pressure. No statistically significant difference was observed in systolic and diastolic blood pressure between normoalbuminuric diabetic children and healthy control children. However, diabetic females aged 15-18 years had significantly higher diastolic blood pressure (75 +/- 1 mmHg, n = 139, mean +/- SE) than healthy control females (72 +/- 1 mmHg, n = 155, p < 0.01), and significantly (p < 0.001) higher body mass index (diabetic females: 22.3 +/- 0.2 kg m-2 vs healthy females: 20.9 +/- 0.2 kg m-2, mean +/- SE.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Relationship between insulin injection regimen and metabolic control in young Danish type 1 diabetic patients. The Danish Study Group of Diabetes in Childhood.

In 1987 and 1989 nationwide screening for HbA1c was carried out in Denmark. Twenty-one paediatric departments treating children with diabetes participated in the first study and twenty-two in the second. During this 2-year period metabolic control deteriorated despite the fact that the use of multiple injection regimens increased from 39% to 54%. The possible reasons for the deterioration in metabolic control were examined in the 429 children (> or = 9 years, 1987) and adolescents (< 18.8 years, 1989) who participated in both studies. All had diabetes duration of greater than one year (1987) and all were treated by the same departments during the study period. The children were divided into three subgroups according to injection regimen. Group A (n = 128) received twice-daily insulin injections; group B (n = 171) were on multiple injections (three or more) while group C (n = 130) shifted from twice-daily insulin to multiple injections during the 2-year period. A deterioration of blood glucose control as assessed by HbA1c was observed in all three treatment groups. For group C the 2-year increase in daily insulin dose was more pronounced for males (19%) than for females (6%). Body mass index increased significantly in all treatment groups during the study period. The 1989 mean levels were higher in group B (males 20.6 kg m-2, females 22.0 kg m-2) than group A (males 19.3 kg m-2, p = 0.002; females 20.7 kg m-2, p = 0.000003) and group C (males 19.4 kg m-2, p = 0.0005; females 20.7 kg m-2, p = 0.008).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Predicting and monitoring of growth in children with short stature during the first year of growth hormone treatment.

Fifteen prepubertal short stature children (10 girls, 5 boys), mean age 9.6 years (range 5.2-12.7 years), with normal response to growth hormone stimulation tests (group A) or partial growth hormone deficiency (GHD) of idiopathic nature (group B) were included in a controlled longitudinal study for evaluation of predictive parameters for the long-term growth response after administration of biosynthetic human growth hormone (B-hGH). The average knee-heel length velocity for the first 3 months was significantly correlated to total body height velocity during the following 9 months (p less than 0.0008). By contrast, this association could not be found for height velocity during the same period. The increase in serum values of alkaline phosphatase and insulin-like growth factor I (IGF-1) during the first month of treatment was not significantly correlated to height velocity during the first year. During one year of treatment with B-hGH the mean height velocity for groups A and B increased from 4.4 cm/year (range 2.5-6.5) to 7.6 cm/year (range 4.7-10.6). Bone age advanced by 1.08 +/- 0.60 per chronological year. The ratio between total height and knee-heel length prior to treatment was 3.34 +/- 0.10 and after one year 3.33 +/- 0.10, suggesting a proportional linear growth. An inverse relationship was observed between the ratio and chronological age. In conclusion, early knee-heel measurement may be a useful non-invasive predictor of long-term linear growth in children during treatment with growth hormone, and the ratio of total height to lower leg length may be of importance in detecting dysproportional growth.

Age Determination by Skeleton↗
PubMed1991

Patient acceptance of Nordiject: a new drug delivery system for growth hormone.

Twenty-seven children, aged 5-20 years, with growth retardation were enrolled in an open study to evaluate the acceptability of a new injection pen (Nordiject 24, Novo Nordisk A/S) for administration of recombinant human growth hormone (r-hGH). Prior to this study, 17 of the patients had been receiving treatment with r-hGH administered via syringes and vials; their experiences with this conventional technique have been used for comparison with Nordiject. The injection pen is provided with a replaceable 27-gauge needle and a cartridge containing 24 IU of reconstituted r-hGH (12 IU/mL). A benzyl alcohol 0.9% solution is used as the solvent for the reconstitution. The pen can be regulated for doses from 0.5 to 8 IU per injection; regulation is accomplished by a turning movement. The patients had no problems with the dissolving procedure or handling the pen. Nearly two-thirds of the patients experienced less injection pain with the pen as compared with the syringe. Special attention was paid to local tolerability, which was reported to be good. The thigh was the preferred injection site. The residual contents from 68 cartridges returned by the patients were analyzed for microbial contamination. Contamination was detected in only one cartridge, which could not be confirmed in a repeated test. Because of the simplification of the injection procedure afforded by the injection pen, 20 of 27 patients were able to perform the injections themselves and hence assume a more active role in their treatment. The patients who previously had been using conventional syringes strongly preferred the pen, and all patients wished to continue using the device.

Adolescent↗
PubMed1990

A nation-wide cross-sectional study of urinary albumin excretion rate, arterial blood pressure and blood glucose control in Danish children with type 1 diabetes mellitus. Danish Study Group of Diabetes in Childhood.

Nation-wide screening for microalbuminuria in Denmark was performed in 22 paediatric departments treating children with Type 1 diabetes. Over a period of 6 months 1020 children (less than or equal to 12 years) and adolescents (greater than 12 to 19 years) were screened (81% of total). Of these, 957 (94%) performed at least two timed overnight urine collections. In 209 non-diabetic subjects the upper 95% limit for normal albumin excretion rate (AER) was 20 micrograms min-1. Mean overnight AER was significantly (p less than 0.001) elevated in diabetic (3.0 x/divided by 2.3 (SD tolerance factor) micrograms min-1) and in non-diabetic (2.5 x/divided by 2.2 micrograms min-1) adolescents compared with diabetic (1.7 x/divided by 2.1 micrograms min-1) and non-diabetic (1.3 x/divided by 2.2 micrograms min-1) children. In the diabetic patients AER was positively correlated with the body surface area and age. Among the patients with Type 1 diabetes, 4.3% (18 males and 23 females) had AER greater than 20 to 150 micrograms min-1 (persistent microalbuminuria). A further 7 adolescents (0.7%) had overt proteinuria (greater than 150 micrograms min-1). Clinical data for the 41 diabetic patients with AER greater than 20 to 150 micrograms min-1 were compared with those for 569 diabetic adolescents with AER less than or equal to 20 micrograms min-1 and duration of diabetes more than 2 years. The group with AER greater than 20 to 150 micrograms min-1 had significantly higher mean age (16.5 years) than the group with AER less than or equal to 20 micrograms min-1 (15.0 years; p less than 0.001). Females with AER greater than 20 to 150 micrograms min-1 had significantly higher mean HbA1c level (10.8 +/- 1.9%) than those with AER less than or equal to 20 micrograms min-1 (9.8 +/- 1.9%, p less than 0.003); they also had impaired linear growth (standard deviation score -0.25 vs + 0.16; p = 0.003). These associations were not found in males. Mean body mass index (BMI) was significantly increased in both females (22.2 +/- 2.9 kg m-2) and males (20.8 +/- 2.7 kg m-2) with AER greater than 20 to 150 micrograms min-1, compared with diabetic patients with AER less than or equal to 20 micrograms min-1 (females 20.8 +/- 3.0 kg m-2, p = 0.02; males 19.7 +/- 2.4 kg m-2, p less than 0.006).(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1988

Glycated haemoglobins.

The association between elevated levels of glycated haemoglobins and diabetes mellitus has been known for twenty years [92]. Since then the determination of glycated haemoglobins has become a valuable tool for the objective assessment of long-term glycaemia in diabetic patients. The marked clinical interest in reliable measurements of glycated haemoglobins has stimulated the development and perfection of the necessary methodology. Limitations of the techniques have led to investigation of the underlying causes. Some of them led to the recognition of processes that were not known to occur in vivo before, such as glycation at sites other than the amino terminus of the beta-chains, modification of haemoglobin by reactants other than glucose or the existence of labile haemoglobin adducts. With ideal methodology these features would have gone unnoticed. Furthermore, the determination of glycated haemoglobin in large populations of diabetic patients has lead to the discovery of new, clinically silent mutant haemoglobins. Today, the routine determination of glycated haemoglobins in diabetic patients probably represents the broadest screening for mutant haemoglobins. The experience with glycated haemoglobins shows that overcoming difficulties in their determination, and progress in biomedical research, are closely intertwined.

Animals↗
PubMed1988

Hemoglobin hafnia: alpha 2 (beta 116 (G18) His----Gln)2; a new hemoglobin variant mistaken for glycated hemoglobin.

Isoelectric focusing of hemolysate from patients with diabetes mellitus is routinely performed to measure their level of HbA1c (glycated hemoglobin). For a 6 year old boy with diabetes mellitus this analysis showed an HbA1c fraction of approx. 50%, which is very unlikely to occur. The possibility of a hemoglobin variant was considered, and by HPLC-separation the presence of two different beta-chains was shown. One tryptic fragment was found to deviate from the normal, and amino-acid analysis and sequence determination revealed the following amino-acid substitution: beta 116 His----Gln. It is the first reported mutation at this position. Functional studies showed almost normal behaviour, consistent with the fact that the affected persons are without any symptoms. In a family survey we found five nondiabetic members with an abnormality similar to the proband. For the variant we chose the name Hafnia, which is Latin for Copenhagen.

Amino Acid Sequence↗
PubMed1988

A nation-wide cross-sectional study of glycosylated haemoglobin in Danish children with type 1 diabetes.

A nation-wide screening for HbA1c was carried out in Denmark. Twenty-one paediatric departments treating children with Type 1 diabetes participated. During a period of 4 months 884 children were included, 93% of all those followed at these centres, representing approximately 70-80% of all children and adolescents with Type 1 diabetes in Denmark. Among the children 351 were less than or equal to 12 years and 533 were adolescents between 12 and 18 years. Children less than or equal to 12 years had a HbA1c concentration of 8.9 +/- 1.5 (+/- SD)% and an insulin dose of 0.71 +/- 0.3 U kg-1 24-h-1. For adolescents HbA1c was significantly higher 9.7 +/- 2.0% (p less than 0.001) and insulin dose significantly increased 0.85 +/- 0.3 U kg-1 24-h-1 (p less than 0.001). Normal range for HbA1c is 4.0-6.5 (mean 5.3)% of total haemoglobin. Boys and girls less than or equal to 12 years had similar HbA1c, but girls received 13% more insulin (p less than 0.001). In the group of adolescents, girls had a HbA1c 4% higher than boys (9.9 +/- 2.0 vs 9.5 +/- 2.0%, p less than 0.025), received 11% more insulin (p less than 0.001), and had 6% higher body mass index (p less than 0.001). A weak correlation was found between insulin dose and the HbA1c level (r = 0.29, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Application of a biokinetic model for prediction and assessment of glycated haemoglobins in diabetic patients.

An improved biokinetic model describing the haemoglobin A1c ketoamine fraction (HbA1c), and the haemoglobin A1d aldimine fraction (HbA1d), as a function of preceding blood glucose levels has been studied. The model requires knowledge of the chemical reaction rate constants and the life span of the erythrocytes. Calculated HbA1c corresponding to constant blood glucose levels was about 6% lower than previously found using a simplified method of calculation. The predicted variations in the glycated haemoglobins in response to simulated variations in the glucose concentration were, however, similar to the improved and the simplified model calculations. Thus, HbA1d reached a new steady state level within 24 h and HbA1c within 4 weeks after sudden change in glucose concentration. When the blood glucose concentration was simulated by sine waves with periods from 2 to 60 days it was observed that the HbA1d varied in parallel with the glucose concentration with a time delay of about 2 h, whereas the HbA1c was almost constant with periods less than 7 days. Haemoglobin A1c predicted from observed blood glucose levels in diabetic patients followed over several weeks varied in parallel with measured HbA1c. However, the measured values were systematically higher than the calculated. This could be due to an underestimation of the daily mean blood glucose levels used for calculation of HbA1c or to inaccurate estimates of the reaction rate constants. Based on the model it could be demonstrated that the HbA1c fraction corresponds to an exponentially weighted average of daily mean blood glucose levels over the preceding 4 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Glucose↗
PubMed1988

Variations in blood constituents of healthy full term infants as related to body weight in the new-born period.

In 59 full term new-born infants an increase in the mean value for (blood, (B] B-haemoglobin, (plasma, (P] P-potassium and (plasma, (P] P-bilirubins was seen during the first three days of life. The erythrocyte volume fraction, P-sodium and P-albumin varied in parallel with the B-haemoglobin concentration. The variation in these blood constituents indicated that an initial destruction of erythrocytes occurred and that a haemoconcentration took place as well. This was further substantiated by the observation of a weight loss in the infants of about 6.4% of the estimated total body water content during the first three days after delivery. An increase in P-sodium of 5% in the same period indicated that the weight loss consisted mainly of water. These results show that new-born infants are prone to be hypovolaemic during the first three days of life.

Body Weight↗
PubMed1988

Anion transport as related to hemoglobin A1c in erythrocytes of diabetic children.

We determined chloride and bicarbonate transport [Jcl and Jbic, nmol/(cm2.s)] under physiological conditions (Cl- 110 and HCO3- 25 mmol per liter, respectively, pH 7.4, 38 degrees C) across the erythrocyte membrane in blood samples from 12 diabetic (Jcl 26.1, SD +/- 3.7, n = 24; Jbic 7.6, SD +/- 0.9, n = 19) and 10 non-diabetic children (Jcl 30.6, SD +/- 4.6, n = 16; Jbic 7.3, SD +/- 1.0, n = 20) with mean hemoglobin A1c values of 11.08% (SD +/- 2.45%) and 5.36% (SD +/- 0.25%), respectively. The concentration of HbA1c, which also reflects the degree of glycation of the membrane proteins, differed significantly (P greater than 0.001) between the two groups, whereas there was no significant variation (P greater than 0.1) in Jcl and Jbic. We conclude that glycation of the integral transport protein in the erythrocyte membrane, capnophorin (also called "band 3"), which mediates a tightly coupled anion exchange, does not change the capacity of the transport system under physiological conditions. Thus the rate-limiting step of the exploitation of the CO2 transport capacity of the blood is not impaired in diabetics and consequently does not endanger the compensatory hyperventilation after ketoacidosis.

Adolescent↗
PubMed1985

Glycated hemoglobin. Reaction and biokinetic studies. Clinical application of hemoglobin A1c in the assessment of metabolic control in children with diabetes mellitus.

The introduction briefly describes the necessity of maintaining a good metabolic control in children with diabetes mellitus. Thereupon, the object of the study is defined, viz. the wish to elucidate glycation of hemoglobin by means of reaction and biokinetic studies and to evaluate the applicability of the glycated hemoglobin fraction HbA1c in the clinical control of children with diabetes mellitus. In the subsequent historical section the most important studies on glycated hemoglobin are reviewed, with a particular view to the formation of this hemoglobin fraction and its clinical applicability. A brief description follows of the pathway in which hemoglobin A, via condensation with glucose, first forms a labile intermediate adduct, designated HbA1d, which is thereafter rearranged to the more stable HbA1c form. The methods used for determining glycated hemoglobin are described and their specificity assessed. In addition, an account is given of the reasons for choosing isoelectric focusing for a further elucidation of the glycation of hemoglobin. Among the results of the present studies it may be mentioned that by using the method of isoelectric focusing for separation of hemoglobin it is possible to: separate HbA1d and HbA1c and to determine the rate and equilibrium constants for the formation and dissociation of these glycated hemoglobin fractions; calculate, by the use of a biokinetic model, that HbA1c reflects the mean blood glucose concentration of the preceding 4 weeks; ascertain that HbA1c is preferable to HbA1 as a parameter for assessing the glycemic control; demonstrate that in children with newly diagnosed diabetes mellitus HbA1c is a useful index for defining the start and cessation of the remission period and for predicting the length of this period; demonstrate that HbA1c in children with diabetes mellitus is positively correlated to the clinical control and negatively correlated to linear growth; demonstrate a seasonal variation in the HbA1c substance fraction which shows the lowest level in the months of June and July; demonstrate that the transport of glucose across the erythrocyte membrane in children with diabetes mellitus is not notably affected by the glycemic control. The final section deals with the possibility whether glycation of hemoglobin and of other proteins can be a contributory cause of long-term diabetic complications.

Blood Glucose↗
PubMed1985

Glucose transport in erythrocytes of diabetic and healthy children as related to hemoglobin A1c.

We studied glucose transport under physiological conditions (38 degrees C, pH 7.2, 5 mmol of glucose per liter) in erythrocytes of nine diabetic children with hemoglobin A1c values ranging from 6.6 to 13.8%, and in erythrocytes from six healthy children. Glucose transport was determined to be 2.38 (SD 0.16) X 10(-10) mol/cm2 X s (n = 18), and 2.47 (SD 0.18) X 10(-10) mol/cm2 X s (n = 12) in erythrocytes from diabetics and controls, respectively. The corresponding values for hemoglobin A1c were 11.0% (SD 2.3%) for the diabetics and 5.6% (SD 0.3%) for the controls. Thus the concentration of hemoglobin A1c, which reflects the degree of glycation of membrane proteins, differs significantly (p less than 0.001) between the two groups, whereas there was no significant variation (p greater than 0.1) in D-glucose transport. We conclude that glycation of the integral membrane protein that mediates glucose transport has no effect on transport function under physiological conditions.

Adolescent↗
PubMed1985

A screening procedure for diabetes in pregnancy.

A screening system for detection of diabetes in pregnancy was carried out in a geographically well-defined unselected population of 2 457 pregnant women all living in the community of Copenhagen. The screening was based on clinical criteria for potential diabetes consisting of previous delivery of a large baby, a family history of diabetes and obesity combined with examination of glucosuria and determination of the fasting blood glucose concentration. It was possible to follow up 95% of all pregnancies. One hundred and ninety women had a positive screening determination and among these women, 24 (1%) were found to have diabetes in pregnancy. It was established that a fasting blood glucose concentration of 4.1 mmol/l was the ideal cut-off point for referring potential diabetics to an oral glucose tolerance test (OGTT). The screening procedure is easy to administer and acceptable for the pregnant woman. The screening OGTT should be performed in the second or third trimester as only one woman had diabetes detected in the first trimester in this study.

Adult↗