A new insulin immunoassay specific for the rapid-acting insulin analog, insulin aspart, suitable for bioavailability, bioequivalence, and pharmacokinetic studies

OBJECTIVES

To validate a specific enzyme-linked immunosorbent assay for the rapid-acting human insulin analogue, insulin aspart, in human serum, human plasma, and porcine plasma.

DESIGN AND METHODS

For the enzyme-linked immunosorbent assay, two murine monoclonal antibodies were developed that bind to two different epitopes on the insulin aspart molecule. Key parameters for validation were imprecision, accuracy, matrix effects, dilution-linearity, and cross-reactivity.

RESULTS

No cross-reactivity was found with human and porcine insulin, human proinsulin, or human C-peptide. The assay is sensitive (limit of quantification = 11.5 pmol/L), accurate (95-107% recovery with human serum, human plasma, and porcine plasma in the range 16-800 pmol/L), and has a 14.7% total imprecision within the entire analytical range. Dilution of samples gave linear results with human serum as the diluent.

CONCLUSIONS

The insulin aspart-specific enzyme-linked immunosorbent assay described in this study is well suited to study the bioavailability, bioequivalence, and pharmacokinetics of this insulin analogue.

Synthesis of epimers of L-cyclopentenylglycine using enzymatic resolution

Both epimers of the naturally occurring nonproteinogenic amino acid L-cyclopentenylglycine, (2S,1'S)- and (2S, 1'R)-2-(cyclopent-2'-enyl)glycine, were obtained via a procedure involving condensation of 3-chlorocyclopentene with diethyl acetylaminomalonate, deethoxycarbonylation, chromatographic separation of the resulting two pairs of enantiomers, and enzymatic resolution of the racemates employing enantioselective hydrolysis of the ethyl ester group with alpha-chymotrypsin. The method was used for preparation of (13)C-labeled compounds of interest for biosynthetic tracer experiments. Enantiomeric purity of the products was determined by chiral HPLC on a Crownpak CR(+) column. The biologically active (2S,1'R) isomer was obtained as a pure compound and characterized for the first time. The (2R,1'R) and (2R,1'S) isomers were obtained as N-acetyl ethyl ester derivatives.

Treatment of breast-cancer-related lymphedema with or without manual lymphatic drainage--a randomized study

A prospective randomized study was carried out to investigate whether the addition of manual lymphatic drainage (MLD) to the standard therapy could improve treatment outcome in women with lymphedema of the ipsilateral arm after breast cancer treatment. Forty-two patients were randomly assigned to receive standard therapy or standard therapy plus MLD 8 times in 2 weeks and training in self-massage. The standard therapy consisted of use of a compression garment, exercises and information about lymphedema and skin care. The efficacy of treatment was evaluated by reduction in lymphedema volume during treatment and by improvement in symptoms potentially related to lymphedema. The patients were followed-up for a total of 12 months. The study showed that both groups obtained a significant reduction in edema and that MLD did not contribute significantly to reduce edema volume.

Seroconversion and seroreversion in IgG antibodies to Helicobacter pylori: a serology based prospective cohort study

STUDY OBJECTIVES

To assess the incidence of seroconversion and seroreversion in IgG antibodies to Helicobacter pylori within a 11 year observation period using these events as markers for acquisition and loss of the infection, respectively.

DESIGN

Population based prospective cohort study.

SETTING

Northern part of Copenhagen County, Denmark.

PARTICIPANTS AND METHODS

A random sample of 2527 Danish adults were examined and blood obtained in 1983 and in 1994. Matching pairs of sera were analysed for the presence of IgG and IgM antibodies to H pylori with an in house enzyme linked immunosorbent assay. Participants who were seronegative at study entry and seropositive at follow up and had a fourfold increase in baseline IgG antibody levels were categorised as seroconverters and regarded as having acquired H pylori infection. Participants who were seropositive at study entry and had at least a fourfold decrease in baseline IgG antibody levels at follow up were assumed to have lost the infection (seroreverters).

RESULTS

The seroprevalence of H pylori infection was 24.7 (95% confidence intervals (95% CI) 23.0, 26.4) % in 1983 and 24.5 (95% CI 22.8, 26. 2) % in 1994. A total of 14 participants seroconverted within the observation period (cumulative 11 year incidence proportion: 1.0 (95% CI 0.5, 1.5) %). Having increased IgM antibody levels at study entry significantly increased the likelihood of IgG seroconversion (relative risk 6.4 (95% CI 2.1, 19.6). Seroreversion was seen in 48 participants (cumulative 11 year incidence proportion: 7.7 (95% CI 5. 6, 9.8) %).

CONCLUSIONS

Changes in H pylori infection status with time are rare in Danish adults. Few adults become infected with H pylori in Denmark.

Pharmacokinetics of the rapid-acting insulin analog, insulin aspart, in rats, dogs, and pigs, and pharmacodynamics of insulin aspart in pigs

The objective of this study was to compare the pharmacokinetics and pharmacodynamics of insulin aspart (IA), a rapidly acting insulin analog, with those of human soluble (regular) insulin (HI) in animal models after s.c. and i.v. dosing. Single doses of IA and HI were administered i.v. and s.c. to rats and dogs at three dose levels, and at one dose level to pigs; rats and dogs also underwent repeated s.c. dosing for 1 week. Plasma insulin levels were assessed at predetermined time points after dosing; plasma glucose levels were measured in pigs only. There were no significant pharmacokinetic differences between IA and HI after a single s.c. or i.v. dose in rats or dogs, and no differences were observed after repeated s.c. dosing, implying there was no accumulation. In pigs, there was a strong trend toward more rapid absorption of IA compared with HI after s.c. dosing, whereas there were no differences after i.v. administration. After s.c. dosing in pigs, IA produced significantly lower plasma glucose levels compared with HI during the period 30 to 75 min after dosing (P <.05). In conclusion, IA was more rapidly absorbed than HI after s.c. administration only in the pig; this difference was reflected in earlier and more pronounced effects on plasma glucose levels.

Fetal growth and adverse birth outcomes in women receiving prescriptions for acetaminophen during pregnancy. EuroMap Study Group

We studied the association between acetaminophen exposure during pregnancy and the prevalence of congenital abnormalities and fetal growth. Our study included 123 women who had received a prescription of acetaminophen during pregnancy and/or 30 days before conception and 13,329 controls who did not receive any prescription at all. We found more malformations among those who received a prescription with an odds ratio of 2.3 (95% CI 1.0-5.4), but the type of malformations did not indicate a causal link. When restricting the study to first time pregnancies, we identified 58 women who received a prescription of acetaminophen during pregnancy and 30 days before conception and 7472 controls. We found no excess risk of malformation [OR = 0.7 (95% CI 0.1-5.5)], and no evidence that acetaminophen should influence fetal growth.

Weekly gemcitabine and cisplatin combination therapy in patients with transitional cell carcinoma of the urothelium: a phase II clinical trial

PURPOSE

To determine the efficacy of gemcitabine and cisplatin combination therapy in patients with advanced and/or metastatic transitional cell urothelial carcinoma.

PATIENTS AND METHODS

Forty-two chemonaïve patients with Karnofsky performance status (KPS) > or = 70 were treated with cisplatin 35 mg/m2 followed by gemcitabine 1000 mg/m2 (30 min i.v. infusion) on days 1, 8, and 15 every twenty-eight days.

RESULTS

Thirty-eight patients were evaluable for efficacy. Half had visceral disease. There were seven complete (18%) and nine partial responses (24%), for a response rate of 42% (95% confidence interval (95% CI): 26%-59%). Responses were independently reviewed. Median response duration was 13.5 months (95% CI: 8.5-18.1 months), median time to progressive disease 7.2 months (95% CI: 4.0-9.1 months) and median survival 12.5 months (95% CI: 8.1-18.7 months); one-year survival was 52%. Laboratory toxicities included leucopenia (44% grade 3; 17% grade 4), neutropenia (25% grade 3; 33% grade 4) and thrombocytopenia (29% grade 3; 49% grade 4). Four patients had grade 4 symptomatic toxicity (three nausea and vomiting, one diarrhoea). There were no grade 4 infections and no toxic deaths.

CONCLUSIONS

The combination of gemcitabine and cisplatin is active in patients with locally advanced and/or metastatic urothelial carcinoma. The weekly schedule of cisplatin is considered inappropriate.

The muscular load on the lower back and shoulders due to lifting at different lifting heights and frequencies

The aim of the study was to investigate the muscular load on the lower back and shoulders and the circulatory load on employees at a post center during repetitive lifting of mail transport boxes. A mock-up was designed in the laboratory, a total of nine combinations of lifting height and frequency were studied. Surface EMG was recorded bisymmetrically from m. erector spinae (L3-level) and m. trapezius. The circulatory load was evaluated by measuring the heart rate. The results show a trade off between the low back and shoulders. The maximum load on the low back occurred at the low lifting height (363 and 54.4 cm) whereas the maximum load on the shoulders occurred at the high lifting height (144.9 and 163.0 cm).

Serum ferritin, hemoglobin, and Helicobacter pylori infection: a seroepidemiologic survey comprising 2794 Danish adults

BACKGROUND & AIMS

Helicobacter pylori infection was recently associated with iron-deficiency anemia. The aim of this study was to examine the relationship between H. pylori infection, hemoglobin, and iron status using serum ferritin as a marker for total body iron.

METHODS

Serum ferritin, hemoglobin, and immunoglobulin G (IgG) antibodies against H. pylori were assessed in 2794 Danish adults who attended a population survey. IgG antibodies were measured with an in-house enzyme-linked immunosorbent assay, serum ferritin with an immunoradiometric assay, and hemoglobin with Coulter-S.

RESULTS

The seroprevalence of H. pylori infection did not relate to hemoglobin. Serum ferritin levels were significantly lower in men (114 vs. 120 microg/L; P = 0.01) and in postmenopausal women (63 vs. 77 microg/L; P = 0.02) who were IgG positive than in seronegative individuals. IgG-positive people more often had reduced serum ferritin levels (</=30 microg/L) than seronegative people. This association persisted in multivariate analysis after adjusting for possible confounding factors (odds ratio, 1.4; 95% confidence interval 1.1-1. 8).

CONCLUSIONS

Serum ferritin levels are reduced in people with increased IgG antibodies to H. pylori. H. pylori infection affects iron metabolism in humans.

Dose titration study of tinzaparin, a low molecular weight heparin, in patients on chronic hemodialysis

The minimal necessary dose of Innohep (IH) (MNDI) (Innohep [tinzaparin], Leo Pharmaceutical Corp., Ballerup, Denmark) was examined in 40 patients switched from conventional heparin ([CH], Leo Pharmaceutical Corp.) to IH and in 13 patients already treated with IH. Clotting in the venous chamber and in the dialyzer was evaluated on a 4 point scale by visual inspection. IH was administrated as a bolus injection into the arterial side of the dialyzer at the beginning of dialysis sessions. The initial dose of IH was 50% of the total dose of CH used before the study (in respective IU). According to clotting in the venous chamber or dialyzer, the dose of IH was titrated by stepwise changes of 500 IU to the lowest possible dose until 3 subsequent dialysis sessions without clotting were obtained. The total dose of CH (bolus and infusion) before switching was 6,162 +/- 2,100 IU. The bleeding time from the cannulation site after dialysis, in 24 patients with A-V fistulas, was 7.1 +/- 2.8 min(triplicates). Eight patients were excluded before achieving the MNDI, 3 due to bleeding not clearly related to heparinization (1 due to gingival bleeding, 1 to epistaxis, and 1 to sugillations), 1 due to alopecia, 2 due to a need of more than 10,000 IU of IH, and 2 patients due to cessation of treatment resulting from anxiety. After switching over, the MNDI amounted to 66 +/- 26% in respective IU. The conversion IH/CH ratio correlated significantly to the blood flow rate and the type of dialyzer. When compared on 3 subsequent sessions before and after switching to IH, no differences were found in the bleeding time after decannulation and in clotting in the venous chamber while dialyzer clotting fell on the visual scale from an average of 0.36 to 0.19 (p < 0.01). No total clot formation was observed during the study. The MNDI correlated positively to the body weight, blood flow rate, and time on dialysis (with the respective coefficients of correlation of r being 0.58, 0.44, and 0.30, p < 0.05) and was also influenced by the type of dialyzer. The average MNDIs for the Hemoflow-FS hollow-fiber (Fresenius, Bad Homburg, Germany), Lundia PRO plate (Gambro, Lund, Sweden), and Polyflux hollow fiber (Gambro) were 2,571, 3,727, and 5,020 IU (p < 0.01, ANOVA). In patients on chronic hemodialysis, IH given as a bolus of 4,250 IU effectively prevented extracorporeal clotting during dialysis, similarly to CH. However, a considerable individual variation in MNDIs not related to the need for CH was observed, and this necessitates individual dosage adjustments to obtain the optimal prevention of clotting with minimal bleeding risk.

A morphometric analysis of nucleoli in cultured carcinoma cells of the human thyroid

Cells from 7 patients operated on for thyroid cancer were investigated. Samples of cells from the carcinoma and from the normal thyroid tissue were cultured with and without TSH stimulation. For light microscopy, serial sections of cells were cut and the size of nucleoli was measured and the number of nucleoli per cell counted. At the electron microscopic level the number and the volume of the fibrillar centres (FC) were estimated taking the Swiss cheese effect into account. The areal densities of FC, the fibrillar and granular component in nucleoli were determined by point counting. The results indicate that the malignant transformation has no influence on the size of the FC, but the observed numbers as well as the total area of FC are larger in cancer cells than in the normal thyroid epithelial cells. The nucleolar density of the fibrillar component is larger and that of the granular component is smaller in thyroid carcinoma cells than in non-malignant thyroid epithelial cells (p = 0.0001). Thus simple morphometry at the electron microscopic level might be helpful to discriminate between thyroid epithelial cells and thyroid carcinoma cells in culture.

[Use of alendronate in osteoporosis--is it cost-effective?]

The objective of the analysis was to establish the cost-effectiveness of five years intervention with alendronate in women aged 65 years with a bone mineral density (BMD) of the femoral neck 2.5 SD below peak bone mass. A cost-utility analysis based on a simulation model was used. The risk of future fractures was estimated on the basis of clinical and epidemiologic data. The costs of intervention and of fracture treatment were based on market prices (measurement of BMD), the Norwegian DRG price list (in-patient hospital care), the pay scale of the Norwegian Medical Association (out-patient care, doctor's visits, laboratory tests, radiographs), public accounts (nursing home care, rehabilitation) and customary charges (transport, physiotherapy etc.). The discounted cost per Quality Adjusted Life Year (QALY) was NOK 528,000, NOK 291,000 and NOK 147,000 when BMD was respectively 1.5, 2.5 and 3.5 SD below peak bone masa at onset of intervention. Sensitivity analyses indicate that the cost per QALY is relatively sensitive to future risk of fracture, cost of intervention, discount rate, and magnitude and duration of the effects of the intervention. The results indicate that the use of alendronate competes favourably with other commonly used preventive programmes when administered to women with high risk of fragility fractures.

Toward understanding insulin fibrillation

Formation of insulin fibrils is a physical process by which partially unfolded insulin molecules interact with each other to form linear aggregates. Shielding of hydrophobic domains is the main driving force for this process, but formation of intermolecular beta-sheet may further stabilize the fibrillar structure. Conformational displacement of the B-chain C-terminal with exposure of nonpolar, aliphatic core residues, including A2, A3, B11, and B15, plays a crucial role in the fibrillation process. Recent crystal analyses and molecular modeling studies have suggested that when insulin fibrillates this exposed domain interacts with a hydrophobic surface domain formed by the aliphatic residues A13, B6, B14, B17, and B18, normally buried when three insulin dimers form a hexamer. In rabbit immunization experiments, insulin fibrils did not elicit an increased immune response with respect to formation of IgG insulin antibodies when compared with native insulin. In contrast, the IgE response increased with increasing content of insulin in fibrillar form. Strategies and practical approaches to prevent insulin from forming fibrils are reviewed. Stabilization of the insulin hexameric structure and blockage of hydrophobic interfaces by addition of surfactants are the most effective means of counteracting insulin fibrillation.

Report of the American Diabetes Association's Task Force on standardization of the insulin assay

Recent large-scale epidemiological studies demonstrate that blood concentrations of immunoreactive insulin predict the development of NIDDM and IDDM and are associated with the risk of several degenerative diseases, such as coronary and peripheral vessel atherosclerosis, hypertension, and dyslipidemia. The reliability of these measurements is dependent on a biological assay that has not been well standardized between laboratories. Recognizing this, the American Diabetes Association organized a task force to assess comparability of blood insulin measurements between laboratories and to suggest techniques to improve comparability. The task force found that identical serum and plasma samples measured in different laboratories produced widely disparate values that were unacceptable for population comparisons. Use of a single reference standard did little to improve comparability. Assay characteristics such as linearity, recovery, accuracy, and cross-reactivity to proinsulin and its primary conversion intermediates varied among the laboratories, and they did not readily explain differences in the measurements made from assay to assay. Use of the same assay kit in different laboratories did not always ensure comparable measurements. Linear regression of assay results from one laboratory to an arbitrarily chosen reference assay greatly improved comparability and demonstrated the potential value in comparing each assay to a reference method. The task force report defines acceptable assay characteristics and proposes a three-step process of insulin assay proficiency and comparability. A central reference assay and ongoing sample exchange will be needed to allow reliable comparisons of insulin measurements made in different laboratories. Rigorous quality control and continuous quality improvement are needed to maintain reliability of the insulin measurement.

[Reduced blood utilization in hip arthroplasty. Introduction of a blood preservation program]

In spring 1992 a blood conservation programme was established at Nordland Central Hospital with emphasis on indications for blood transfusion and intraoperative blood salvage (cell-saver). Medical records from all patients who underwent hip arthroplasty during the period 1 June 1991 to 28 February 1994 were examined. Mean transfusion of homologous SAGMAN-blood (bank blood) was substantially reduced during the period: for total prosthesis (n = 192) from 2.6 to 1.1 units per operation (p < 0.0001) and for hemiprosthesis (n = 66) from 3.1 to 0.9 units per operation (p = 0.0202). The percentage of patients in each of these two groups who did not receive blood transfusion at all increased from 18 to 61 in the first group (p < 0.0001) and from 24 to 65 (p = 0.0202) in the second. The substantial reduction of bank blood transfusion in this material conforms with current international transfusion guidelines. A particular benefit, considering the risk of transfusing contagious blood, is the marked increase in the number of patients who did not receive any blood product at all.

Odontological identification of fire victims--potentialities and limitations

A retrospective study was performed to analyse the power of odontological evidence in burn victims. The material comprised 292 single fire cases registered at 4 centers of forensic odontology in Scandinavia (DK: Aarhus, Copenhagen; N: Oslo; S: Goteborg) covering a 10-year period. Filed antemortem (am) and postmortem (pm) data were critically reviewed and registered. New systems for classification of the degree of injuries to the teeth and jaws and of the quality of dental records were developed. Matching dental am-pm units/features were recorded using the tooth as unit. Units were scored as either ordinary or extraordinary if the frequency of occurrence in a Danish reference population was > or = 10% or < 10%, respectively. The ID conclusion of a single case was classified into one of the categories: no conclusion, ID possible, ID probable or ID established, depending on the number of ordinary/extraordinary matching units. All age groups were represented. Most fatal burns occurred in house fires (62%) and there was a preponderance of males (71%). Detailed written records supplied by single or by systematic radiographs were available in 71% of cases. About 50% of burn victims were classified into the no-injury group and approximately 25% of cases showed injuries to the anterior teeth only. The number and complexity of dental restorations increased with age. The dental examination was a powerful tool in identification of burn victims. Thus, dental identity (ID) was established in 61% of burn victims and dental evidence assisted the identification in another 31% (ID possible 19%; ID probable 12%).(ABSTRACT TRUNCATED AT 250 WORDS)

A methodical study of shape changes in human oral cells perturbed by a simulated orthodontic strain in vitro

Cells are known to alter their shape as a response to physical and chemical changes. Mechanical loads applied to teeth produced cellular perturbations resulting in orthodontic movement. An in vitro model was developed to simulate the in vivo strain of orthodontic movement. Calibrated forces were applied to human periodontal ligament cells and buccal mucosal fibroblasts (controls). A biaxial strain-producing device was used to stretch vital cells growth on flexible polytetrafluorethylene membranes. In addition, a new cell adhesive, Cell Tak, was employed to examine the effect of an adhesive substrate on the cellular response to two known loads. The shape changes of unstrained (control) and strained cells were evaluated by time-lapse telemicroscopy, and plots of time-dependent alterations in area and shape were recorded. The fusiform cells became more rounded over a given time of up to 1400 s. The responses appeared to be independent of cell type, the strain employed, and the presence of cell adhesive. Scanning electron microscopy demonstrated, irrespective of cell type, that the surface of stressed cells produced a striking number of microvilli as compared with the relatively smooth-surfaced controls.

Individual identification by means of conventional bitewing film and subtraction radiography

An analysis of simulated post- and antemortem (p.m. and a.m.) victim radiographs was performed. Existing pairs of bitewing radiographs randomly sampled from a large population of adolescents were used. Two categories of individuals were included based on dental therapy conditions (none or few simple fillings). Subtraction images were performed of pairs of bitewings originating from the same individual (identical images) and different individuals (non-identical images) within each group. Four observers were asked to match the bitewings and to assess the subtraction images with respect to identity based on the score system: 1 = 'eliminated', 2 = 'possible', 3 = 'likely', or 4 = 'certain'. Three observers each mismatched the film radiographs among two out of 12 individuals without fillings. True positive identification (identified by scores 2 + 3 + 4) of subtraction images were made in 10-12 individuals out of a possible 12. The range of false positive (FP) and false negative (FN) scorings was 3-15 and 0-2, respectively. All observers were capable of correctly matching bitewings originating in the 12 individuals with amalgam fillings. By use of subtraction radiography, 12-14 identical images out of a possible 15 were assessed correctly. The range of FP and FN scorings of subtraction images in this group was 1-4 and 1, respectively. Defining only score 4 as positive identification, the sensitivity of the subtraction technique decreased from approximately 0.90 to 0.70 in both categories of individuals, while specificity increased to almost 1.00 from 0.82 vs. 0.96 in the categories with and without dental restorations. Bitewing radiographs from single individuals within a group of individuals were sufficiently identical to allow for valid identification by a strict criterion. The subtraction technique may add to the subjective matching of radiographs as a screening test in victim identification.

[Bone lengthening of the extremities using the Ilizarov method]

We describe the indications and the results in 18 bone lengthenings carried out on 14 patients in our department during the period January 1991 to September 1993. Seven patients had limb length inequality, five patients had dysplasia or aplasia, one patient had Turner's syndrome and one patient had suffered traumatic amputation of all the fingers of one hand. The mean lengthenings achieved were: femur 4.9 cm; tibia 5.6 cm; fibula 1.5 cm; humerus 7.5 cm; ulna 3.5 cm; radius 1.9 cm; and metacarpals 1.6 cm. There were 14 cases of pin-problems which needed surgery. Nine cases of infection around the pin holes were treated with antibiotics only. We had five cases with severe pain due to distraction. We had two cases of fracture after removal of the external fixation. Both fractures healed without further problems, but in one case there was three cm loss of the achieved lengthening. Our conclusion is that the Ilizarov method for bone lengthening is a demanding procedure. Because of the many--often minor--complications the patients must be seen frequently, as one must be prepared for "aggressive" treatment of the problems.