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Biomedical subjects

G Smits

Publications and source records attributed to G Smits.

11 recordsLinked to original sources
PubMed2000

An examination of different Percoll density gradients and magnetic activated cell sorting (MACS) for the enrichment of fetal erythroblasts from maternal blood.

OBJECTIVE: To increase the yield of fetal erythroblasts from the blood of pregnant women by optimising and simplifying the enrichment procedure. METHODS: By using an experimental system whereby cord blood was mixed with normal adult blood, we evaluated the recovery of fetal erythroblasts using different single or double percoll density gradients with or without subsequent enrichment by Magnetic Activated Cell Sorting (MACS). RESULTS: The recovery of erythroblasts on single density gradients increased from 3%-68% of the input erythroblasts with an increase in the density of percoll from 1075 g/l-1098 g/l. Although the use of a double density gradient did eliminate most lymphocytes, it was accompanied by a significant loss of erythroblasts. The combination with MACS enrichment, however, lead to a almost 200 fold increase in the purity of erythroblasts. CONCLUSIONS: Erythroblasts are preferentially retained by higher density gradients. To enhance their purity a subsequent more specific enrichment step, such as MACS is advisable.

Blood Cell Count↗
PubMed1998

Microstaging of pT1 transitional cell carcinoma of the bladder: identification of subgroups with distinct risks of progression.

OBJECTIVES: To evaluate microstaging by means of quantifying the depth of invasion of the subepithelial connective tissue in pT1 transitional cell carcinoma (TCC) of the bladder for its additional prognostic value with respect to disease recurrence and progression. METHODS: We reviewed the pathologic findings of a consecutive series of 124 patients with pT1 tumors entered in a prospective randomized multicenter trial comparing mitomycin C and bacillus Calmette-Guérin treatment, with at least 3 years of follow-up and clinical outcome hidden from reviewers. The depth of invasion was established by identifying submucosal tumor invasion up to, in, or beyond the muscularis mucosae or vascular plexus and classified as pT1a, pT1b, or pT1c, respectively. In addition to tumor grade, the presence of carcinoma in situ (CIS) near the primary tumor or in biopsy specimens taken from abnormal looking mucosa was taken into account. The risks of recurrence and progression were calculated using Kaplan-Meier curves and modeled with proportional hazard models. RESULTS: pT1 subclassification was possible in more than 90% of the specimens. The 3-year risk of recurrence was not different in any of the subgroups. By contrast, the Kaplan-Meier 3-year risk for progression was 6%, 33%, and 55% for pT1a, pT1b (hazard ratio [HR] 5.51), and pT1c (HR 12.35) tumors, respectively (log-rank test P < 0.001). The Kaplan-Meier 3-year risk of progression was 9% versus 39% (HR 5.62) for the absence or presence of CIS in the tumor (P=0.001) and 8% versus 49% (HR 6.72) for CIS in biopsy specimens (P < 0.001). Tumor grade had no statistically significant prognostic value with respect to progression, nor had tumor volume or multifocality. The combination of the parameters (pT1c and CIS) increased the risk of progression by a factor of 27 (P < 0.0001) compared with the absence of pT1c and CIS. CONCLUSIONS: These data show that the extent of lamina propria invasion (pT1a, pT1b, pT1c) is a clinically relevant prognostic factor for progression of pT1 TCC of the bladder. With the combination of this pT1 subclassification and the presence of CIS subgroups, distinct risks of progression can be identified that may give additional information for follow-up and treatment policies.

Adjuvants, Immunologic↗
PubMed1995

Psychometric characteristics and validity of the Dutch adaptation of the Buss-Durkee Hostility Inventory (the BDHI-D).

Data are presented on the factorial structure, internal consistency, and validity of the Dutch adaptation of the Buss-Durkee Hostility Inventory (the BDHI-D). Factor analyses of the responses of 463 subjects revealed two scales measuring Overt Aggression and Covert Aggression. The reliability of both subscales is good. Concordance with other self-report measures reveals satisfactory convergent and divergent validity.

Adolescent↗
PubMed1995

On the presence of inulin and oligofructose as natural ingredients in the western diet.

The classic definitions of inulin and oligofructose are constructively criticized. It is observed that inulin cannot unequivocally be described as a polydisperse 1-kestose-based (GFn) beta (2-->1) linear fructan chain, but that inulin always contains small amounts of Fm and branched molecules. This review article describes the presence of inulin and oligofructose in common foodstuffs. Historical data on human consumption add an extra dimension. Modern analytical techniques (HPLC, LGC, HPAEC-PAD) are used to check the variety of data mentioned in the literature throughout the past century. Methods to determine inulin and oligofructose in natural foodstuffs (cereals, fruit, and vegetables) are optimized and used to determine the loss of inulin during storage and during preparation of the food. These findings allow quantification of the amount of inulin and oligofructose in the average daily western diet. The daily per capita intake is estimated to range from 1 to 10 g, depending on geographic, demographic, and other related parameters (age, sex, season, etc.). Inulin and oligofructose are not measured by classic methods of dietary fiber analysis and consequently are often not mentioned in food tables. Their significant contribution (1 to 10 g/d/per capita) to the dietary fiber fraction (recommended at 25 g/d/per capita) is not taken into account in any nutritional recommendations. In view of this, inulin and oligofructose deserve more attention, both in food composition tables and in diet or nutrition studies.

Diet↗
PubMed1995

Decrease of optic disc cupping and pallor of ocular hypertensives with timolol therapy.

PURPOSE: The purpose of this study was to determine whether timolol drops compared to placebo drops had a significant effect on optic disc cupping and pallor in ocular hypertensives. METHODS: Thirty-seven ocular hypertensives were randomly assigned to placebo or 0.5% timolol drops to both eyes in a double masked clinical trial. Measurements of ocular pressure and photographs of the optic disc for cupping by photogrammetry and pallor by computerized image analysis were made at about 3 month intervals, for 18 to 24 months of follow-up. RESULTS: None of the subjects developed visual field loss when tested with the Goldmann perimeter by kinetic and static means at six month intervals. Subjects treated with timolol developed a significant decrease in ocular pressure and a significant decrease in optic disc cupping with a smaller decrease in pallor compared to subject treated with placebo. Multivariate analyses indicated that the decrease of optic disc cupping and pallor was not associated with the ocular pressure on treatment or the decrease in ocular pressure during the trial. CONCLUSION: Timolol treatment was associated with a decrease in optic disc cupping and pallor. The effect of timolol appears to be related to mechanisms other than the decrease in ocular pressure.

Double-Blind Method↗
PubMed1995

Increase of retinal nerve fiber layer thickness in ocular hypertensives with timolol therapy.

PURPOSE: The purpose of this study was to determine whether timolol drops compared to placebo drops had a significant effect on retinal nerve fiber layer thickness in ocular hypertensives. METHODS: Thirty-seven ocular hypertensives were randomly assigned to receive placebo or 0.5% timolol drops to both eyes for 18 to 24 months in a double masked clinical trial. Measurements of ocular pressure and photographs of retinal nerve fiber layer using stereophotogrammetric techniques were made at about 3 month intervals for 18 to 24 months of follow-up. RESULTS: None of the subjects developed visual field loss when tested with the Goldmann perimeter by kinetic and static means at six month intervals. Subjects treated with timolol had a significant decrease in ocular pressure and developed a significant increase in retinal nerve fiber layer thickness compared to subjects treated with placebo. Multivariate analyses indicated that the increase of retinal nerve layer thickness was not associated either with the ocular pressure on treatment or the decrease in ocular pressure on treatment. CONCLUSION: Timolol treatment was associated with an increase of retinal nerve fiber thickness. The effect of timolol appears to be related to mechanisms other than the decrease in ocular pressure.

Double-Blind Method↗
PubMed1994

Rapid kinetics of glucose uptake in Saccharomyces cerevisiae.

In a multiple deletion mutant hxt1deltahxt2deltahxt3delta hxt4deltasnf3delta of Saccharomyces cerevisiae growing on a 2% glucose, high-affinity glucose-uptake (low Km) was exhibited throughout growth on glucose in contrast to the wild-type, which exhibited the usual low-affinity to high-affinity transition as the glucose in the medium was consumed. Elevated levels of invertase activity throughout growth on glucose, in this mutant as compared to the wild-type, indicate that glucose repression may be impaired. However, in a mutant containing only the HXT2 gene (hxt1deltahxt3deltahxt4deltasnf3delta), invertase levels were similar to those in the wild-type. It is likely, therefore, that some of these putative glucose transporters, such as HXT2, also have regulatory roles in cellular metabolism. In triple hexose-kinase mutants, rapid (200-ms) measurements of initial glucose-uptake revealed high-affinity glucose uptake (Km approx. 2 mmol/L) while measurements on the slower 5-s scale clearly demonstrate that uptake is not linear over this longer period. These results suggest that this high-affinity component does not require a functional hexose-kinase.

Biological Transport↗
PubMed1989

Eating in combat: a survey of U.S. Marines.

A survey of U.S. Marines was conducted in order to investigate the effect of combat, a highly stressful situation, on eating behavior. The results indicate that Marines reduced their food intake, especially during their first combat experience. The principle reason cited for reduced consumption during combat was the lack of time to eat and prepare food. However, fear was important in accounting for reduced consumption during the marines' initial exposure to combat. The results are consistent with other laboratory and survey findings that stress leads to a reduction in food intake.

Adult↗
PubMed1986

Effect of head-out water immersion on response to exercise training.

During spaceflight and head-out water immersion (WI) there is a cephalad shift in blood volume. We have recently shown that left ventricular end-diastolic dimension is significantly greater during moderate cycling exercise with WI compared with on land. The purpose of this study was to determine whether the cephalad shift in blood volume and accompanying increase in cardiac preload with WI alters the normal cardiovascular adaptations to aerobic exercise training. Nine middle-aged healthy men trained on cycle ergometers in water, nine trained on land, and four served as controls for 12 wk. Following training, both training groups showed similar increase (P less than 0.05) in stroke volume and similar decreases in heart rate (P less than 0.01) and blood pressure (P less than 0.05) at a given submaximal exercise O2 consumption (VO2). Maximal VO2 increased (P less than 0.01) similarly for both training groups. The control group did not demonstrate any significant changes in submaximal or maximal exercise responses. We conclude that the cephalad shift in blood volume with WI does not alter the normal cardiovascular adaptation to aerobic exercise training.

Adult↗
PubMed1976

Evaluation of the Vitatron "AKES" modification for optimal use in routine enzyme analysis.

The Vitatron has been used as designed by the manufacturer under routine laboratory conditions (Broughton, P.M.G., Buttolph, M.A., Gowenlock, A.H., Neill, D.W. and Sleutelberg, R.G. (1969) J. Clin. Pathol. 22, 278). We assessed the possibilities of the AKES with regard to determination of the activities of three enzymes: alanine transaminase (AIT), aspartate transaminase (AsT) and lactate dehydrogenase (LDH) in serum. Precision, accuracy, carry over and sample-diluent contamination were evaluated. This resulted in recommendations for optimal use in terms of capacity and precision, which were supported by computations on a mathematical model for measuring results.

Alanine Transaminase↗