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Biomedical subjects

H J Smit

Publications and source records attributed to H J Smit.

At least 19 recordsLinked to original sources
PubMed2006

Is a patient's self-reported health-related quality of life a prognostic factor for survival in non-small-cell lung cancer patients? A multivariate analysis of prognostic factors of EORTC study 08975.

BACKGROUND: The aim of this prognostic factor analysis was to investigate if a patient's self-reported health-related quality of life (HRQOL) provided independent prognostic information for survival in non-small cell lung cancer (NSCLC) patients. PATIENTS AND METHODS: Pretreatment HRQOL was measured in 391 advanced NSCLC patients using the EORTC QLQ-C30 and the EORTC Lung Cancer module (QLQ-LC13). The Cox proportional hazards regression model was used for both univariate and multivariate analyses of survival. In addition, a bootstrap validation technique was used to assess the stability of the outcomes. RESULTS: The final multivariate Cox regression model retained four parameters as independent prognostic factors for survival: male gender with a hazard ratio (HR) = 1.32 (95% CI 1.03-1.69; P = 0.03); performance status (0 to 1 versus 2) with HR = 1.63 (95% CI 1.04-2.54; P = 0.032); patient's self-reported score of pain with HR= 1.11 (95% CI 1.07-1.16; P < 0.001) and dysphagia with HR = 1.12 (95% CI 1.04-1.21; P = 0.003). A 10-point shift worse in the scale measuring pain and dysphagia translated into an 11% and 12% increased in the likelihood of death respectively. A risk group categorization was also developed. CONCLUSION: The results suggest that patients' self-reported HRQOL provide independent prognostic information for survival. This finding supports the collection of such data in routine clinical practice.

Adult↗
PubMed2006

Effects of perennial ryegrass cultivars on milk yield and nitrogen utilization in grazing dairy cows.

The effects of 4 diploid perennial ryegrass cultivars that differed in water-soluble carbohydrate (WSC) concentrations on milk yield and nitrogen (N) utilization in dairy cows were evaluated in a 2-yr grazing experiment. Twelve lactating dairy cows were assigned to 1 cultivar for a 2-wk period in a 4 x 4 Latin square design with 3 replicates. Each year, the experiment lasted 8 wk. Swards were in a vegetative stage throughout the experiment. Herbage constituents were determined, and DM intake was estimated with the n-alkane technique. Nitrogen utilization was calculated as N excreted in milk divided by N intake, assuming a zero N retention. Two cultivars had consistently higher WSC concentrations and slightly lower neutral detergent fiber concentrations than the other 2 cultivars. The ranking of the cultivars in chemical composition traits in both years was rather consistent. Cows grazing the cultivar with the lowest concentration of WSC had the lowest herbage DM intake, N intake, milk yield, and milk N yield in 2002, but with a similar difference in WSC concentration, no differences among cultivars were found in 2003. In both years, milk urea N concentration was slightly higher for cows grazing the cultivar with the lowest WSC concentration, although it was significant only in 2003. Nitrogen utilization (N milk:N intake, g/g) varied between 0.241 and 0.246 in 2002 and between 0.190 and 0.209 in 2003, and in both years there was no effect of cultivar. At relatively high N concentrations in grass and only small differences among cultivars in neutral detergent fiber concentrations, cultivars with an elevated WSC concentration did not increase N utilization in grazing dairy cows.

Animal Feed↗
PubMed2005

Comparison of techniques for estimating herbage intake of grazing dairy cows.

For estimating herbage intake during grazing, the traditional sward cutting technique was compared in grazing experiments in 2002 and 2003 with the recently developed n-alkanes technique and with the net energy method. The first method estimates herbage intake by the difference between the herbage mass before and after grazing and the regrowth between the 2 points in time. The second technique estimates herbage intake by the ratio of a dosed even-chain synthetic n-alkane (C32) and a naturally occurring odd-chain n-alkane (C31 or C33) in the herbage and feces. The third technique calculated the intake from the animal's energy requirements for milk production and maintenance. The sward cutting technique estimated herbage intake with the highest coefficient of variation and had different results in the 2 experimental years. The n-alkanes method yielded less variable results, whereas the net energy method gave the least variable results. In 2002, the estimates of the alkane ratio C32:C33 were best related with estimations of the net energy method. In 2003, the estimates of the alkane ratio C32:C31 were best related. The estimate based on the alkane ratio C32:C33 had a lower coefficient of variation than the one based on the alkane ratio C32:C31. Therefore, the C32:C33 alkane method was considered to be a better direct estimator for herbage intake by grazing lactating dairy cows.

Alkanes↗
PubMed2005

Effects of perennial ryegrass cultivars on intake, digestibility, and milk yield in dairy cows.

The effects of 8 diploid perennial ryegrass (Lolium perenne L.) cultivars on dry matter (DM) intake, DM digestibility, and milk yield (MY) of dairy cows were evaluated in the summer of 2000 and 2001. Each summer, herbage was harvested daily and stall-fed to 12 dairy cows during six 2-wk periods. Six cultivars were fed in 3 periods (1, 3, and 5) according to a double 3 x 3 Latin square design. In the other periods (2, 4, and 6), 2 cultivars were fed in a repeated measurement design. Herbage mass and leaf blades in the sward canopy varied among cultivars, but differences were not consistent between years. The largest differences in herbage composition were found in water-soluble carbohydrate content, followed by crude protein content. only small differences were found in the neutral detergent fiber (NDF) content. A higher water-soluble carbohydrate content was found in 2 cultivars in both years, whereas ranking of cultivars in crude protein and NDF content was not consistent with years. Dry matter intake and MY were not affected by cultivar. In both years, DM digestiblity was high (>77%), with very small differences among cultivars in 2000 (<0.5%) and larger differences in 2001 (up to 4%). This was associated with a delayed heading date in 2001, resulting in larger differences in leaf blades and NDF content among cultivars. It may be concluded that the 8 cultivars used in our experiments do not provide grass breeders with encouraging evidence to include selection criteria for an increased DM intake, DM digestibility, and MY in their grass breeding schemes.

Animal Nutritional Physiological Phenomena↗
PubMed2004

Mood and cognitive performance effects of "energy" drink constituents: caffeine, glucose and carbonation.

Three studies using healthy volunteers (n = 271) investigated the effects of caffeine, carbohydrates and carbonation in functional "energy" drinks (EDs) with the aim of determining their benefit in every-day life. The results showed caffeine to be the main ED constituent responsible for the effects found, with possible minor, relatively weak effects of carbohydrates. EDs were found to improve and/or maintain mood and performance during fatiguing and cognitively demanding tasks relative to placebo. In terms of absolute values, EDs maintained levels of arousal compared to a deterioration in arousal where placebo was consumed. These effects were found in caffeine-deprived participants, and so may be largely due to "withdrawal reversal". There were only minor differences in the effects of water vs. "sensory-matched" placebo, supporting previous findings indicating that the type of placebo does not alter the conclusions drawn about the effects of the full ED. Finally, carbonation had various effects on mood, some of which were present immediately following consumption, others were consistent with slower absorption of caffeine (and possibly carbohydrates) from carbonated drinks.

Adolescent↗
PubMed2003

Electrical impedance tomography to measure pulmonary perfusion: is the reproducibility high enough for clinical practice?

A possible clinical application of electrical impedance tomography (EIT) might be to monitor changes in the pulmonary circulation, provided the reproducibility of the EIT measurement is adequate. The purpose of this study was threefold: the intra- and inter-investigator variability of repeated measurements was investigated. Three different regions of interest (ROI) were analysed to assess the optimal ROI. Twenty-four healthy subjects and six patients were included. The Sheffield applied potential tomograph (DAS-01P, IBEES, Sheffield, UK) was used. Electrodes were attached by investigator A, and duplicate EIT measurements were performed. After detachment and 45 min of rest, the protocol was repeated by another investigator B, and afterwards by the initial investigator A. Three ROIs were analysed: whole circle, 'inner half circle' and contour. The mean difference in impedance changes between observers is presented in arbitrary units (AU) +/- SD. Finally, the influence of age, body composition and sex on the EIT result was examined. For the contour ROI, the mean difference for the intra-investigator situation was -1.44 x 10(-2) +/- 18.45 x 10(-2) AU (-0.7 +/- 9.0%), and was 5.46 x 10(-2) +/- 21.66 x 10(-2) AU (2.7 +/- 10.8%) for the inter-investigator situation. The coefficient of reproducibility of the intra- and inter-investigator reproducibility varied between 0.89 and 0.97 for all ROIs (P < 0.0001). There is a relation between impedance change and age (correlation coefficient r = -0.63, P < 0.01 for contour ROI), and between impedance change and body mass index (BMI) (r = -0.53, P < 0.05). We found a significant difference in mean impedance change between groups of males and females. In conclusion, EIT results are highly reproducible when performed by the same investigator as well as by two different investigators.

Adolescent↗
PubMed2002

Epoprostenol-induced pulmonary vasodilatation in patients with pulmonary hypertension measured by electrical impedance tomography.

Electrical impedance tomography (EIT) has been proposed as a method to monitor dynamic changes in the pulmonary vascular bed. In this study we examined the validity of EIT in the measurement of pulmonary vasodilatation in eight patients with primary and secondary pulmonary hypertension when given the vasodilating agent epoprostenol (Flolan). Therefore, catheterization of the pulmonary artery was performed in the ICU and the cardiac output was measured by means of the Fick method. The pulmonary vascular resistance (PVR) and mean pulmonary arterial pressure (mPAP) were determined. Epoprostenol was given in increasing doses to test reversibility of pulmonary hypertension. The maximum test dose was 12 ng kg(-1) min(-1). During each step simultaneous EIT (DAS-01 P Portable Data Acquisition System, Sheffield, England) measurements were performed with the 16 electrodes equidistantly positioned in the third intercostal space. The maximal systolic impedance change, relative to end-diastole, deltaZperf, was chosen as a measure of pulmonary perfusion. The impedance change between baseline and highest tolerable epoprostenol concentration was compared with the change in PVR. The mean PVR (dyn s/cm5) decreased from 636 (+/-399) to 366 (+/-242); p < 0.01. DeltaZperf (in arbitrary units) for the whole patient group increased from 901 (+/-295) x 10(-3) to 1082 (+/-472) x 10(-3) (p<0.05). Only one patient showed a reduction in pulmonary artery pressure >20%, which is defined as significant vasodilatation. A strong relationship was found between the impedance changes and the change in PVR and mPAP in the patient with a significant vasodilatation on epoprostenol. From these results we conclude that EIT is a reliable method to measure blood volume changes due to pharmacologically induced vasodilatation in the pulmonary bed.

Adult↗
PubMed2000

Effects of low doses of caffeine on cognitive performance, mood and thirst in low and higher caffeine consumers.

RATIONALE: Caffeine is present in many widely consumed drinks and some foods. In the fairly extensive literature on the psychostimulant effects of caffeine, there are few dose-response studies and even fewer studies of the effects of doses of caffeine lower than 50 mg (the range of the amounts of caffeine contained in, for example, a typical serving of tea or cola). OBJECTIVE: This study measured the effects of 0, 12.5, 25, 50 and 100 mg caffeine on cognitive performance, mood and thirst in adults with low and moderate to high habitual caffeine intakes. METHODS: This was a double-blind, within-subjects study. Following overnight caffeine abstinence, participants (n=23) completed a test battery once before and three times after placebo or caffeine administration. The test battery consisted of two performance tests, a long duration simple reaction time task and a rapid visual information processing task, and a mood questionnaire (including also an item on thirst). RESULTS: Effects on performance and mood confirmed a psychostimulant action of caffeine. All doses of caffeine significantly affected cognitive performance, and the dose-response relationships for these effects were rather flat. The effects on performance were more marked in individuals with a higher level of habitual caffeine intake, whereas caffeine increased thirst only in low caffeine consumers. CONCLUSIONS: After overnight caffeine abstinence, caffeine can significantly affect cognitive performance, mood and thirst at doses within and even lower than the range of amounts of caffeine contained in a single serving of popular caffeine-containing drinks. Regular caffeine consumers appear to show substantial tolerance to the thirst-increasing but not to the performance and mood effects of caffeine.

Adolescent↗
PubMed2000

Food craving and food "addiction": a critical review of the evidence from a biopsychosocial perspective.

Although certain commonalities exist between eating and drug use (mood effects, external cue-control of appetites, reinforcement, etc. ), it is argued that the vast majority of cases of (self-reported) food craving and food "addiction" should not be viewed as addictive behavior. An explanation is proposed that instead gives a prominent role to the psychological processes of ambivalence and attribution, operating together with normal mechanisms of appetite control, the hedonic effects of certain foods, and socially and culturally determined perceptions of appropriate intakes and uses of those foods. Ambivalence (e.g., "nice but naughty") about foods such as chocolate arises from the attitude that it is highly palatable but should be eaten with restraint. Attempts to restrict intake, however, cause the desire for chocolate to become more salient, an experience that is then labelled as a craving. This, together with a need to provide a reason for why resisting eating chocolate is difficult and sometimes fails, can, in turn, lead the individual to an explanation in terms of addiction (e.g., "chocoholism"). Moreishness ("causing a desire for more") occurs during, rather than preceding, an eating episode, and is experienced when the eater attempts to limit consumption before appetite for the food has been sated.

Affect↗
PubMed2000

Do bullae indicate a predisposition to recurrent pneumothorax?

A relationship between idiopathic spontaneous pneumothorax (ISP) and visible parenchymal bullae and blebs has been reported. The causal relationship between blebs and bullae and ISP is questionable. Consequently, resection of the involved area is only indicated if it predisposes to recurrence of the pneumothorax. CT studies on 101 cases of ISP were analysed. The presence of bullae and their distribution was then related to the first and recurrent pneumothorax. CT demonstrated bullae in 56% of first ISP and in 64% of recurrent ISP, mostly among older patients. Only eight patients had bullae larger than 2 cm on the side of the pneumothorax. The location of the bullae was not a factor in predicting recurrent pneumothorax.

Adult↗
PubMed1999

Analysis of pleural fluid in idiopathic spontaneous pneumothorax; correlation of eosinophil percentage with the duration of air in the pleural space.

Pleural fluid analysis was performed in patients with idiopathic spontaneous pneumothorax. The objective of the study was to define the cell differentiation, and part of the cytokine profile, in relation to the duration of pneumothorax. In the 23 consecutive patients (19 men, mean age 34.2 years, 17 smokers), pleural fluid was obtained immediately after chest tube drainage (n = 6), or during thoracoscopy (n = 17). Cytospins were carried out, and supernatant analysis of the different cytokines was performed using sandwich ELISA. All concentrations were corrected for dilution. The duration of the pneumothorax was correlated with the rise in eosinophil percentage (r = 0.81, P < 0.00001) in pleural fluid. RANTES, platelet-activating factor (PAF), and monocyte chemotactic protein-1 (MCP-1) were detectable but no relationship with eosinophils or duration of the pneumothorax was found. Granulocyte-macrophage colony stimulating factor (GM-CSF) and interluekin-8 (IL-8) were not detectable. Interleukin-5 (IL-5) concentration correlated with the eosinophil concentration (r = 0.84, P = 0.037) and the eosinophil percentage (r = 0.68, P = 0.005) in the pleural fluid. Idiopathic spontaneous pneumothorax causes a time-related rise in the eosinophil percentage in the pleural space, which correlates with the level of IL-5.

Adult↗
PubMed1999

Atmospheric pressure changes and outdoor temperature changes in relation to spontaneous pneumothorax.

STUDY AIMS: To examine the influence of atmospheric pressure (AP) and temperature changes on the incidence of idiopathic spontaneous pneumothorax (SP). METHODS: From December 1991 through November 1993, 115 consecutive SP cases were selected. Patients were included after being in Amsterdam at least 1 full day before contracting the SP. Differences in air temperature and AP (provided hourly by the national weather bureau) for the days of the SP occurrence and the days previous to it were recorded to measure influences of air temperature and AP. The correlation between days with lightning and SP and clustering of SP was evaluated. RESULTS: SP occurred on 14.7% of the days in the 2-year period. There was no relationship between SP and a rise or fall in AP (Poisson regression). There was an average temperature rise of 0.57 degrees C from the day prior to the day of the SP, compared with a 0.08 degrees C fall on the days without SP. This difference is statistically significant and was consistent over the four seasons and both years. Seventy-three percent of the SP cases were clustered. A relationship between SP and thunderstorms was found. CONCLUSIONS: AP differences do not seem to influence the chance of developing SP. SP occurs in clusters, and more often 1 to 2 days after thunderstorms. Whether the identified temperature rise prior to the SP is a causative factor is unlikely; coexisting weather phenomena might explain this unexpected finding and should be studied in the future.

Adult↗
PubMed1998

The impact of spontaneous pneumothorax, and its treatment, on the smoking behaviour of young adult smokers.

The pneumothorax, and its often invasive treatment, are impressive events in otherwise healthy young patients. The relationship between smoking behaviour and the idiopathic spontaneous pneumothorax (ISP) is explained to the patients. The objective of the study was to analyse whether smoking behaviour of patients is influenced by the ISP (re-) event, and its treatment. Of 145 consecutive ISP patients (1991-1995), 112 were tobacco smokers at time of the first ISP. Of the 112, 106 participated in a confidential telephone questionnaire survey combined with retrospective medical record analysis. Smoking cessation and reduction percentage related to ISP events, and its treatment, were the outcome measurements. All patients (mean age 28.8 years at the first ISP) were aware of the relationship between smoking, and ISP at time of the first ISP. Age, pack years, and different treatment modalities had no influence on smoking cessation or reduction. Some 86.2% of the male and 80.8% of the female patients continued smoking after the first ISP, despite the known relationship between smoking, and contracting spontaneous pneumothorax, and despite its often invasive treatment. In the group of recurrent pneumothorax events 73.3% continued smoking.

Adult↗
PubMed1998

Talc-induced inflammation in the pleural cavity.

Talc administration into the pleural cavity induces pleurodesis. To obtain further insight into the inflammatory process that causes pleurodesis, the cellular kinetics in the pleural space after the administration of talc was studied, along with its relation to chemokine concentrations in the pleural fluid. Thirteen consecutive patients with idiopathic spontaneous pneumothorax and eight patients with malignant pleural effusions received talc pleurodesis. The first group was treated with talc poudrage, whereas the second group was treated with talc slurry. Pleural fluids were isolated before talc administration as well as 3, 6, 24, 48 and 72 h afterwards. The talc induced a rapid polymorphonuclear neutrophil (PMN) influx followed by an accumulation of macrophages. In addition, increased production of interleukin (IL)-8 and monocyte chemotactic protein (MCP)-1 was observed. The talc-induced PMN influx reached its maximum after 3-24 h, and was related to the IL-8 concentration. In contrast, the MCP-1 was not related to the macrophage accumulation. Talc-induced inflammation in patients with idiopathic spontaneous pneumothorax and malignant pleural effusion is characterized by an influx of polymorphonuclear neutrophils related to interleukin-8, followed by an accumulation of monocytes.

Adult↗
PubMed1996

Is resection of bronchiectasis beneficial in patients with primary ciliary dyskinesia?

A retrospective study of 21 patients with primary ciliary dyskinesia (PCD) was done. Thirteen had prior resection of bronchiectasis and eight had not. Information about present complaints was obtained by a questionnaire. The prevalence of present respiratory symptoms was the same in both groups. The surgical patients had more severe disease and 85% of them considered the operation beneficial. Selected patients with PCD may have improved conditions with resection of bronchiectasis.

Adult↗