Search PubMed⌕ Search

Biomedical subjects

R van Strik

Publications and source records attributed to R van Strik.

At least 55 records · Page 3Linked to original sources
PubMed1987

Long-acting somatostatin analogue (Sandostatin) reduces late night insulinopenic ketogenesis in diabetic teenagers.

Ten diabetic teenagers were admitted into our hospital for two nights, separated by one week. In a double-blind cross-over randomized study they received either 50 micrograms of the new long-acting somatostatin analogue Sandostatin sc or placebo. All patients were between 12 and 16 years of age, C-peptide negative with a duration of diabetes of at least four years. They had either conventional therapy or insulin pump therapy. Insulin doses and diets were kept unchanged. Blood samples were taken half hourly from 17.00 h until 09.30 h the next morning from an indwelling venous catheter. Hormonal and metabolic profiles on the two nights were evaluated by means of a distribution free time sequential co-movement analysis and by the paired Wilcoxon's signed rank test. After Sandostatin was given at 22.00 h, GH levels were significantly suppressed during 4 h. During that period blood glucose was slightly but significantly lower than after placebo. The free-insulin profiles from both nights were very comparable. Co-movement analysis showed a significant correlation between glucose and free insulin variations with a 30-min backward shift of the glucose curve. However, after Sandostatin administration this relation was lost in the period between 22.00 and 07.00 h, indicating a different effect of insulin on glucose levels during the nights Sandostatin was given. Early morning glucose rises were associated with free insulin levels below 20 mU/l. This association was not altered during the Sandostatin nights. Glucagon was not suppressed by Sandostatin except at 120 min after injection, and remained unchanged during the rest of the observation period.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Hydroxybutyric Acid↗
PubMed1986

Overnight metabolic profiles in very young insulin-dependent diabetic children.

UNLABELLED: The magnitude of the disturbance of metabolic control in diabetes mellitus in very young children has been recognised, but seldom studied. Limitations to studies are set by the difficulty of obtaining control data and until recently the lack of alternative therapies. Recently "mini" pumps for continuous subcutaneous insulin delivery have become available and may offer an alternative therapeutic possibility. The present investigation has been undertaken to collect overnight metabolic data of very young diabetic children (less than 6 years) controlled by standard injection therapy. During one admission to hospital frequent blood samples were collected for free insulin, glucose, alanine, lactate, glycerol and 3-hydroxybutyrate determinations. In all children (n = 9) the profiles showed a steep rise in glucose from 04.30 h (6.2 +/- 1.3 mmol/l) to 09.30 h (17.8 +/- 2.4 mmol/l) (the so-called "dawn-phenomenon"). The nature of the changes in the intermediary metabolites suggested that rise in blood glucose was caused by insufficient insulin. We have attempted to explore the time relationship between the overnight drop in free insulin levels and the rises in blood glucose by a distribution-free statistical analysis, correlating successive changes in time between the two profiles. The analysis suggested a delay of 2-6 h between free insulin levels and their effects. IN CONCLUSION: a clear "dawn phenomenon" is seen in very young diabetic children, and contributes to their poor glycaemic control. More stable and higher insulin concentrations in the early morning, obtained perhaps by continuous subcutaneous insulin infusion, might ameliorate the overall glycaemic control in the very young diabetic child.

Age Factors↗
PubMed1986

Minimizing interlaboratory variation in routine assays of serum cholesterol through the use of serum calibrators.

A cholesterol standardization program was developed in The Netherlands for clinical laboratories that use their analytical results as indicators of cardiovascular risk. Participants with sufficient precision but inaccurate results are encouraged to use serum-based calibrators as a means to decrease bias. A regional pilot survey and thereafter a national one were carried out in 31 and 138 laboratories, respectively, to investigate whether use of the serum-calibration procedure could improve routinely performed cholesterol measurements. To participants in our national quality-control surveys were mailed three calibrators (pooled human serum) and five human-serum controls, for analysis of cholesterol on four different days. Reference method values had been assigned to the calibrators by the Netherlands Reference Laboratory, applying the U.S. Centers for Disease Control modification of the Abell-Kendall procedure. Using the calibration curves based on results for the serum calibrators decreased the between-laboratory variation (SD) by at least 50%, with improved accuracy for non-enzymatic methods. The initial within-laboratory precision was generally good, and improvements in it were small. To our knowledge, standardization results involving so many routine hospital laboratory procedures have not been previously reported.

Calibration↗
PubMed1985

Measurement of human small airway smooth muscle function in vitro with the bronchiolar strip preparation.

The technique by which human bronchiolar strips are prepared is described in detail. The biological viability of the preparations after storage at 4 degrees C overnight and the reproducibility of contractile responses to KCl and methacholine were examined in lung tissue from six patients. Measurements were performed on the first and second day after surgical resection. On both days, most bronchioles showed an increase in contractility. The responses on the first day were not different from those on the second day. No significant changes in time were found for pD2 and slope of the methacholine dose-response curves. The variability of responses between patients was significantly larger than between strips within patients. The pD2 was the best reproducible parameter.

Bronchi↗
PubMed1984

Hepatitis B antigen and antibody in the blood of prostitutes visiting an outpatient venereology department in Rotterdam.

We took blood samples from 128 prostitutes visiting the outpatient venereology department of the University Hospital, Rotterdam-Dijkzigt to test for the presence of hepatitis B surface antigen (HBsAg) and antibody to hepatitis B surface antigen (anti-HBs). The prevalence of anti-HBs was found to be significantly higher in the group of prostitutes than in "normal populations", and we concluded that more of the former had been in contact with the hepatitis B virus (HBV). We recommend that the advice on vaccination of the hepatitis B committee of the Health Council of The Netherlands should be followed by screening prostitutes for the presence of HBsAg and anti-HBs in the blood, and vaccinating those who have no anti-HBs.

Adolescent↗
PubMed1983

Evaluation of accuracy of 20 different test kits for the enzymic determination of cholesterol.

We evaluated the accuracy of 20 different test kits for the enzymic determination of cholesterol. Using a selected set of standards, we found mean values differing by -9.9 to + 10.7% from values obtained by the Abell-Kendall procedure. Nine kits gave values with a relative bias of less than 2.5%. In the case of the other 11 kits, recalculation with secondary serum standards resulted in values within 5% of the reference values. Depending on the kit used, two different commercially available standard solutions produced results differing by, at most, 8.7%. We obtained indirect evidence that use of esterase of bacterial origin is associated with low values. We ascribe the high values obtained with some kits to positive interference by stabilizers or unspecified compounds in the reagents.

Cholesterol↗
PubMed1978

The nose provocation and the passive anterior rhinometry (PAR).

The authors describe an easy and fast way of nose provocation (aerosol provocation combined with passive anterior rhinomanometry). A comparative study between skin tests, lungprovocations and noseprovocations proves the usefulness of the method.

Adolescent↗
PubMed1978

Analysis of fat-soluble vitamins. XIX. Collaborative studies on the chemical assay for vitamin D concentrates.

In 1971, a chemical method for the assay of vitamin D in concentrates containing only vitamin D was collaboratively studied by 14 laboratories, using 6 different samples from 2 European manufacturers. On the basis of these results, the laboratories were divided into 2 groups: 5 with significant laboratory biases of greater than or equal to 2%, and 9 laboratories with nonsignificant bias. The 9 laboratories were subdivided into 2 groups which differed significantly as to reproducibility within laboratories. The reproducibility between laboratories, expressed as a standard deviation in per cent with 95% confidence limits, was 1.2% (confidence range 0.6-7.3) and 4.7% (confidence range 2.4-29.3) for 3 and 6 laboratories, respectively. A second collaborative test was performed in 1974, using 12 vitamin D resin samples in oil from 3 United States manufacturers, to compare 2 chemical vitamin D assay methods (with and without maleic anhydride) and to compare results from the chemical and biological methods; 9 laboratories participated in the chemical method study and 3 in the rat bioassay study. The correlation of results of the chemical method including maleic anhydride treatment and the rat bioassays was satisfactory. The reproducibility of the chemical method was about the same as that in the first collaborative test.

Fats↗
PubMed1977

Cryoprecipitated plasma perfusion preservation and cold storage preservation of duct-ligated pancreatic allografts.

It has been shown previously that, at least in dogs, a vascularized pancreatic allograft with ligation of the pancreatic duct can maintain normal beta-cell function for at least 5 years. In this study common organ preservation techniques, as used in human cadaveric kidney transplantation, were applied to canine pancreatic allografts to determine the influence of 24-hour preservation on beta-cell function, graft survival and histological appearances. Three groups of dogs were compared: group A consisted of 9 dogs with fresh grafts; group B consisted of 5 dogs who received grafts preserved for 24 hours by pulsatile hypothermic cryoprecipitated plasma perfusion; and group C was composed of 5 animals who received grafts that had been flushed with Collins' solution followed by hypothermic storage for 24 hours. It appeared that both preservation methods were equally effective and that preservation did not alter either the graft's function or its histological appearance. No significant differences after transplantation were observed in the endocrine function tests of the three groups when compared with the preoperative values; neither was there a significant difference in the mean graft survival time between the groups.

Animals↗
PubMedDate not supplied

Lung function and bronchial responsiveness in children who had infantile bronchiolitis.

A number of studies have shown that children who had infantile bronchiolitis are at increased risk of recurrent episodes of wheezing. A genetic predisposition to atopy is mentioned in some studies and is contested by others. Lung function abnormalities and increased bronchial responsiveness (BR) have been described after infantile bronchiolitis. We investigated children who had had the clinical syndrome of bronchiolitis during infancy and compared them with asthmatic and healthy children of the same age regarding bronchial caliber, smooth muscle tone, and responsiveness to histamine. Lung function was measured by forced oscillometry. We found that most children with current symptoms had either decreased baseline bronchial caliber, increased bronchial smooth muscle tone, or increased BR. These patients are comparable to mild asthmatics. The children without current symptoms are comparable to healthy children in these respects. Recurrent respiratory symptoms after bronchiolitis should be regarded as mild asthma and treated as such.

Asthma↗
PubMedDate not supplied

Uveal melanoma: updated considerations on current management modalities.

Published data on growth rates of uveal melanomas and effects of treatment modalities raise important considerations. Dissemination from uveal melanomas starts after the tumour is larger than 7 mm diameter; growth from 7 to 10 mm diameter increases the risk of metastases incrementally to approximately 16%. Estimations of tumour doubling times indicate that metastatic death before 8 years is nearly always due to pre-therapeutic dissemination so that the impact on survival by therapy can only be assessed thereafter. Histopathology on irradiated melanomas reveals that reproductive activity has not been suppressed and the anticipated (and unfavourable) risk of metastases is not balanced by poor post-irradiation visual acuity. Also the psychological well-being of a patient with a functional fellow eye is better after primary enucleation. Conservative management is most appropriate for: small melanomas, patients with a short life expectancy, melanomas in a single functioning eye, and patients refusing enucleation.

Combined Modality Therapy↗
PubMedDate not supplied

Excessive prolongation of the bleeding time by aspirin in essential thrombocythemia is related to a decrease of large von Willebrand factor multimers in plasma.

Patients with essential thrombocythemia (ET), who frequently have bleeding complications, may manifest an excessive prolongation of the bleeding time (BT) after ingestion of aspirin (ASA). The reason for this excessive prolongation of the BT is unknown, but it is attributed to qualitative platelet defects. Since patients with ET may also have acquired abnormalities of plasma and platelet von Willebrand factor (vWF), we questioned whether the excessive prolongation of the BT by ASA was related to changes in either plasma or platelet vWF. To that end, we studied BT and plasma and platelet vWF in ten ET patients, ten patients with reactive thrombocytosis (RT), and ten normal individuals, both before and after administration of 500 mg ASA for 7 days. In a second study, the effect of DDAVP infusion on plasma vWF in relation to the BT was studied in ten normal individuals and ten ET patients after treatment with 100 mg ASA for 3 days. In the first study, treatment with ASA resulted in a significant prolongation of the BT in normal subjects, RT patients, and ET patients. However, in five ET patients an excessive (> 2 SD) prolongation of the BT by ASA was observed. Although ASA induced no direct changes in either plasma or platelet vWF levels in either normal subjects, RT patients, or ET patients, all five ET patients who showed an excessive prolongation of the BT by ASA had significantly decreased levels of large vWF multimers in plasma. In the second study, infusion with DDAVP resulted in a significant increase in plasma large vWF multimers, paralleled by a normalization of (excessively) prolonged BT. Our data suggest that in ET inhibition of platelet function by ASA in the presence of concurrently decreased levels of large vWF multimers in plasma may have provoked the excessive BT prolongation.

Adult↗
PubMedDate not supplied

Experience with a modified solid-phase enzyme immunoassay for detection of gonorrhea in prostitutes.

The modified Gonozyme Test (Abbott Laboratories; Chicago, IL), a new enzyme immunoassay for detection of Neisseria gonorrhoeae, was evaluated in testing of 266 prostitutes. When the enzyme immunoassay was used with material from the cervix, the prevalence of gonorrhea was 8.4%. As compared with culture results, this rate represents a sensitivity of 88% and a specificity of 99.2%. A sensitivity of 71% and a specificity of 98.9% were registered for tests of urethral material. In a comparison of the two tests without accepting either one as standard, the sensitivity of the enzyme immunoassay was 90% for material from the cervix and the specificity was 100%. There are several possible causes for discordance between results of culture and of enzyme immunoassay. The high predictive value of a negative enzyme immunoassay in screening urogenital samples from prostitutes makes this test very suitable for rapid elimination of gonorrhea from this pool of patients.

Adult↗