Biomedical subjects

B van den Berg

Publications and source records attributed to B van den Berg.

At least 19 recordsLinked to original sources

PubMed2006

[Psychotherapeutic treatment options for bipolar disorders. A review of randomized controlled studies].

BACKGROUND: Until recently research into the efficacy of treatment of bipolar disorders focused mainly on the pharmacological treatment. Over the last few years more and more research has concentrated on the psychological treatments for bipolar disorders. aim To review published, controlled and randomised studies dealing with the efficacy of forms of psychotherapeutic treatment for bipolar disorders. METHOD: By searching Medline and Embase using the search terms, 'psychotherapy', 'cognitive (behavioural) therapy', 'family therapy' and 'psychoeducation' we found eight relevant reports of randomised, controlled trials, which described the interventions that were undertaken and recorded the relapse rates. RESULTS: The following forms of treatment were investigated: Relapse-Prevention Plan, Cognitive Behavioural Therapy, Interpersonal and Social Rhythm Therapy, Family-Focused Treatment and Group Psychoeducation. These forms of treatment were used in addition to standard pharmacological treatment. The addition of psychotherapeutic treatment was found to reduce lower the relapse rate, to lead to less hospitalisation and to improve functioning. CONCLUSION: The authors recommend that patients with bipolar disorders be offered psychotherapeutic treatment because it is likely to lower the risk of relapse.

Bipolar Disorder↗

PubMed2004

Burden of informal caregiving for stroke patients. Identification of caregivers at risk of adverse health effects.

BACKGROUND: We assessed the objective and subjective burden of caregiving for stroke patients and investigated which characteristics of the patient, the informal caregiver and the objective burden contribute most to subjective burden and to the condition of feeling substantially burdened. METHODS: We studied a sample of 151 stroke survivors and their primary informal caregivers. We collected data through patient and caregiver interviews 6 months after stroke. RESULTS: Both the level of subjective burden and the condition of feeling substantially burdened were associated with both caregiver's and patient's health-related quality of life, patient's age, and the number of caregiving tasks performed. CONCLUSIONS: These conditions can be used in clinical practice to identify potentially vulnerable caregivers in need of support and at risk of adverse health effects. Monitoring stroke survivors as well as their family caregivers at discharge may help to prevent or alleviate caregiver burden.

Adaptation, Psychological↗

PubMed2004

The desire for support and respite care: preferences of Dutch informal caregivers.

Informal care is an indispensable element in the care for many patients. In order to maintain a sustainable input of informal care, it seems important to identify measures to alleviate the burden of care giving for caregivers at risk of burn out or other serious health problems, such as support and respite care. Thus, far research has focused on the burden of caregiving and on the supply of respite care. The demand side: what type of care is preferred by informal caregivers and what determines their preferences, is virtually unknown. We analysed the preferences and the underlying determinants for several types of support and respite care in a sample of 950 Dutch informal caregivers. Almost 80% of the respondents desire support or respite care in general, 42-47% would prefer more communication with other informal caregivers or more information of professional caregivers. Some time off is preferred by 40% of the respondents. The results show that caregiver characteristics, care recipient characteristics, elements of the caregiving situation and institutional variables determine the desire for support and respite care. Especially, the subjective burden of caregiving is important, whereas the number of caregiving tasks and the time invested (objective burden) hardly affect the desire for support and respite care.

Aged↗

PubMed2004

What really matters: an inquiry into the relative importance of dimensions of informal caregiver burden.

OBJECTIVE: Prevailing measures of subjective caregiver burden either have no overall summary score or do not consider the relative importance caregivers attach to different dimensions of burden. Our aim was to assess which dimensions informal caregivers perceive as being important to their overall burden from care giving. DESIGN: Cross-sectional. SUBJECTS: Data were pooled from two Dutch samples of primary informal caregivers covering a wide range of chronic care-giving situations: caregivers for stroke survivors (n = 196) and caregivers for individuals with rheumatoid arthritis (RA) (n = 131). MAIN MEASURES: Subjective burden of care giving was assessed using the Caregiver Reaction Assessment (CRA) and the Self-Rated Burden scale (SRB). RESULTS: In the total sample four of the five dimensions of the CRA were found to contribute to the overall subjective burden experienced by informal caregivers. In the individual stroke and RA samples only two of the five dimensions emerged as relevant. SRB scores were significantly higher for caregivers of stroke patients, but no differences were found for the five dimensions of the CRA between the two samples. CONCLUSIONS: The dimensions of CRA are not equally important to the overall subjective burden of informal caregivers. To assess overall subjective burden, a measure based on a caregiver's own assessment of burden such as SRB needs to be used in addition to prevailing measures.

Arthritis, Rheumatoid↗

PubMed2003

Dimension-specific burden of caregiving among partners of rheumatoid arthritis patients.

OBJECTIVES: To assess subjective caregiver burden among partners of rheumatoid arthritis (RA) patients and to identify partner and patient variables and objective caregiver burden related to subjective caregiver burden. METHODS: In 2001, 134 patients diagnosed with RA and their caregiving partners participated in a postal questionnaire survey. Information was gathered on age, gender and health problems of patient and partner, disease duration of the patient, objective caregiver burden and subjective caregiver burden of the partner (using the multidimensional Caregiver Reaction Assessment). Correlation coefficients were computed between the subjective caregiver burden dimensions. Multivariate analyses were performed to identify variables that explained the variation in subjective burden. RESULTS: Partners of RA patients derived, on average, a high level of self-esteem from giving care. Negative subjective caregiver burden was to a large degree caused by a disrupted schedule and to a smaller degree by a lack of family support, financial problems and loss of physical strength. Problems of the partner with mobility or with pain/discomfort and problems of the patient with self-care activities and activities of daily life had the largest impact on negative levels of subjective caregiver burden. CONCLUSIONS: Health parameters of the patient and partner have a considerable predictive value for the development of high levels of subjective burden in partners of RA patients. Support strategies should be developed for partners of RA patients, and should focus especially on reducing the burden caused by a disrupted schedule, and simultaneously on increasing the focus of caregivers on the positive aspects of caregiving.

Adult↗

PubMed2003

Intoxication with therapeutic and illicit drug substances and hospital admission to a Dutch university hospital.

BACKGROUND: This article describes the retrospective analysis of the patients who presented with a drug-related intoxication to the emergency department of the Erasmus Medical Centre in 2000. METHODS: Data were collected from the emergency department's electronic database and the medical charts of the patients. RESULTS: A total of 243 patients were seen with a drug-related intoxication caused by ingestion of one or more medical substances, drugs of abuse (DOA) or combinations with alcohol. Mono-intoxication occurred in 58% of the patients, predominantly caused by DOA (56 patients), analgesics (17 patients) or benzodiazepines (14 patients). Benzodiazepines (55 patients), analgesics (42 patients), alcohol (42 patients), DOA (40 patients) and antidepressants (23 patients) were predominant in combined intoxications. More than half of the patients (142) were discharged after being treated in the emergency department and 80 patients were admitted to the wards. Eighteen patients were admitted elsewhere and three patients were lost to follow-up. Eventually, 70 patients were discharged after having been admitted, five patients were admitted to other institutions, two patients died and three patients were lost to follow-up. CONCLUSIONS: DOA, benzodiazepines, analgesics, alcohol and antidepressants accounted for approximately 65% of the drug-related intoxications in 2000 and in a third of the presenting patients, toxicity was such that admission to the wards was warranted.

Adult↗

PubMed2001

Effect of series of resistance levels on flow limitation in mechanically ventilated COPD patients.

In severe chronic obstructive pulmonary disease (COPD) lung emptying is disturbed by airways compression and expiratory flow limitation. Application of an external resistance has been suggested to counteract airways compression and improve lung emptying. We studied the effect of various resistance levels on lung emptying in mechanically ventilated COPD patients. In 18 patients an adjustable resistor was applied. The effect on airways compression was assessed by iso-volume pressure--flow curves (IVPF) and by interrupter measurements. Respiratory mechanics during unimpeded expirations were correlated to the results obtained with the resistances. The resistances caused an increase in iso-volume flow at the IVPF-curves in six patients, indicating that airways compression was counteracted. Interrupter measurements showed that overshoots in flow (as measure of flow limitation) were significantly reduced by the resistor. These effects could be predicted on basis of respiratory mechanics during unimpeded expiration. In conclusion, mechanically ventilated COPD patients can be identified in whom application of external resistances counteracts airways compression and reduces flow limitation.

Airway Resistance↗

PubMed2001

Effect of expiratory resistance on gas-exchange and breathing pattern in chronic obstructive pulmonary disease (COPD) patients being weaned from the ventilator.

BACKGROUND: The majority of patients with severe chronic obstructive pulmonary disease (COPD) have flow limitation, which has deleterious side effects. If these patients are mechanically ventilated, this often results in difficult weaning. Spontaneously breathing COPD patients experience a beneficial effect of pursed lip breathing. We investigated whether in intubated COPD patients application of an external resistance could produce the same beneficial effects on breathing pattern and gas-exchange as pursed lip breathing. METHODS: Ten COPD patients with flow limitation were studied during pressure support mechanical ventilation. Two types of expiratory resistances were applied: one fixed level of resistance and one with a resistive pressure decay. Each resistance was applied in 5 patients and the highest level was chosen that did not cause hyperinflation. Blood gas values and breathing pattern with and without resistance were compared. RESULTS: With resistance 1, gas-exchange and breathing pattern did not change significantly; average PCO2 changed from 8.0 to 8.1 kPa, PO2 from 10.2 to 10.3 kPa, tidal volume from 0.380 to 0.420 l, respiratory rate from 25 to 23 bpm and inspiratory:expiratory ratio from 1:1.9 to 1:2.0. With resistance 2, gas-exchange and breathing pattern did not change significantly; average PCO2 changed from 5.8 to 6.0 kPa, PO2 from 11.1 to 12.1 kPa, tidal volume from 0.733 to 0.695 l, respiratory rate from 16 to 18 bpm and inspiratory:expiratory ratio from 1:2.3 to 1:2.9. CONCLUSION: In intubated COPD patients being weaned from the ventilator, application of an external resistance did not have the same beneficial effects as pursed lip breathing.

Aged↗

PubMed2000

Macromolecular crowding perturbs protein refolding kinetics: implications for folding inside the cell.

We have studied the effects of macromolecular crowding on protein folding kinetics by studying the oxidative refolding of hen lysozyme in the absence and presence of high concentrations of bovine serum albumin and Ficoll 70. The heterogeneity characteristic of the lysozyme refolding process is preserved under crowded conditions. This, together with the observation that the refolding intermediates that accumulate to significant levels are very similar in the absence and presence of Ficoll, suggests that crowding does not alter substantially the energetics of the protein folding reaction. However, the presence of high concentrations of macromolecules results in the acceleration of the fast track of the refolding process whereas the slow track is substantially retarded. The results can be explained by preferential excluded volume stabilization of compact states relative to more unfolded states, and suggest that, relative to dilute solutions, the rates of many protein folding processes are likely to be altered under conditions that more closely resemble the intracellular environment.

Ficoll↗

PubMed2000

Expiratory time constants in mechanically ventilated patients with and without COPD.

OBJECTIVE: In mechanically ventilated patients, the expiratory time constant provides information about the respiratory mechanics and the actual time needed for complete expiration. As an easy method to determine the time constant, the ratio of exhaled tidal volume to peak expiratory flow has been proposed. This assumes a single compartment model for the whole expiration. Since the latter has to be questioned in patients with chronic obstructive pulmonary disease (COPD), we compared time constants calculated from various parts of expiration and related these to time constants assessed with the interrupter method. DESIGN: Prospective study. SETTING: A medical intensive care unit in a university hospital. PATIENTS: Thirty-eight patients (18 severe COPD, eight mild COPD, 12 other pathologies) were studied during mechanical ventilation under sedation and paralysis. MEASUREMENTS AND RESULTS: Time constants determined from flow-volume curves at 100%, the last 75, 50, and 25% of expired tidal volume, were compared to time constants obtained from interrupter measurements. Furthermore, the time constants were related to the actual time needed for complete expiration and to the patient's pulmonary condition. The time constant determined from the last 75% of the expiratory flow-volume curve (RCfv75) was in closest agreement with the time constant obtained from the interrupter measurement, gave an accurate estimation of the actual time needed for complete expiration, and was discriminative for the severity of COPD. CONCLUSIONS: In mechanically ventilated patients with and without COPD, a time constant can well be calculated from the expiratory flow-volume curve for the last 75% of tidal volume, gives a good estimation of respiratory mechanics, and is easy to obtain at the bedside.

Case-Control Studies↗

PubMed1999

Effects of macromolecular crowding on protein folding and aggregation.

We have studied the effects of polysaccharide and protein crowding agents on the refolding of oxidized and reduced hen lysozyme in order to test the prediction that association constants of interacting macromolecules in living cells are greatly increased by macromolecular crowding relative to their values in dilute solutions. We demonstrate that whereas refolding of oxidized lysozyme is hardly affected by crowding, correct refolding of the reduced protein is essentially abolished due to aggregation at high concentrations of crowding agents. The results show that the protein folding catalyst protein disulfide isomerase is particularly effective in preventing lysozyme aggregation under crowded conditions, suggesting that crowding enhances its chaperone activity. Our findings suggest that the effects of macromolecular crowding could have major implications for our understanding of how protein folding occurs inside cells.

Animals↗

PubMed1999

The oxidative refolding of hen lysozyme and its catalysis by protein disulfide isomerase.

The oxidative refolding of hen lysozyme has been studied by a variety of time-resolved biophysical methods in conjunction with analysis of folding intermediates using reverse-phase HPLC. In order to achieve this, refolding conditions were designed to reduce aggregation during the early stages of the folding reaction. A complex ensemble of relatively unstructured intermediates with on average two disulfide bonds is formed rapidly from the fully reduced protein after initiation of folding. Following structural collapse, the majority of molecules slowly form the four-disulfide-containing fully native protein via rearrangement of a highly native-like, kinetically trapped intermediate, des-[76-94], although a significant population (approximately 30%) appears to fold more quickly via other three-disulfide intermediates. The folding catalyst PDI increases dramatically both yields and rates of lysozyme refolding, largely by facilitating the conversion of des-[76-94] to the native state. This suggests that acceleration of the folding rate may be an important factor in avoiding aggregation in the intracellular environment.

Animals↗

PubMed1999

Characterisation of the dominant oxidative folding intermediate of hen lysozyme.

Reduced denatured lysozyme has been oxidised and refolded at pH values close to neutral in an efficient way by dilution from buffers containing 8.0 M urea, and refolding intermediates were separated by reverse-phase HPLC at pH 2. By using peptic digestion in combination with high-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry (MS) and tandem MS/MS the dominant intermediate was identified to be des-[76-94]. This species has three of the four native disulphide bonds, but lacks the Cys76-Cys94 disulphide bond which connects the two folding domains in the native protein. Characterisation of des-[76-94] by 2D1H NMR shows that it has a highly native-like structure. This provides an explanation for the accumulation of this species during refolding as direct oxidation to the fully native protein will be restricted by the burial of Cys94 in the protein interior.

Amino Acid Sequence↗

PubMed1999

Flow-volume curves as measurement of respiratory mechanics during ventilatory support: the effect of the exhalation valve.

OBJECTIVE: To assess the feasibility of expiratory flow-volume curves as a measurement of respiratory mechanics during ventilatory support: to what extent is the shape of the curve affected by the exhalation valve of the ventilator? DESIGN: Prospective, comparative study. SETTING: Medical intensive care unit of a university hospital. PATIENTS: 28 consecutive patients with various conditions, mechanically ventilated with both the Siemens Servo 900C and 300 ventilators, were studied under sedation and paralysis. INTERVENTIONS: The ventilator circuit was intermittently disconnected from the ventilator at end-inspiration in order to obtain flow-volume curves with and without the exhalation valve in place. MEASUREMENTS AND RESULTS: Peak flow (PEF) and the slope of the flow-volume curve during the last 50 % of expired volume (SF50) were obtained both with and without the exhalation valve in place. The exhalation valve caused a significant reduction in peak flow of 0.3 l/s (from 1.27 to 0.97 l/s) with the Siemens Servo 900 C ventilator and of 0.42 l/s (from 1.36 to 0.94 l/s) with the Siemens Servo 300 ventilator (p < 0.001). The SF50 was not affected. CONCLUSION: In mechanically ventilated patients, the exhalation valve causes a significant reduction in peak flow, but does not affect the SF50. This study further suggests that the second part of the expiratory flow-volume curve can be used to estimate patients' respiratory mechanics during ventilatory support.

APACHE↗

PubMed1999

Expiratory flow-volume curves in mechanically ventilated patients with chronic obstructive pulmonary disease.

BACKGROUND: Forced expiratory flow-volume curves are commonly used to assess the degree of airflow obstruction in patients with chronic obstructive pulmonary disease (COPD). In mechanically ventilated subjects, expiratory airways obstruction can only be estimated from relaxed expirations. The aim of this study was to quantify the degree of airways obstruction from relaxed expiratory flow-volume curves in mechanically ventilated patients with COPD. METHODS: As measure of airflow obstruction, the effective time constant during the last 50% of expired volume (tau) was calculated. For bedside monitoring, tau was recalculated as the slope of the flow during the last 50% of expired volume (SF50). In order to study reproducibility, the variables were calculated from consecutive breaths and at different levels of end-expiratory lung volume (EEV). The SF50 and the tau-were correlated with the forced expiratory volume in 1 s (FEV1) measured prior to the start of ventilatory support. RESULTS: Twenty-seven patients were studied with a FEV1 expressed as percentage predicted of 31 +/- 12% (mean +/- SD). The SF50 amounted to 19 +/- 10 degrees. A positive linear correlation was established between SF50 and the FEV1, (%pred), (r = 0.90, P < 0.0001). The tau showed an exponential relationship with FEV1 (%pred), (r2 = 0.78). From 5 consecutive breaths the mean variation coefficient of SF50 was 5 +/- 2%. Changes of delta EEV from 0.05 to 1.00 L did not affect the SF50-values. In 12 patients, mechanically ventilated for respiratory diseases other than COPD, mean tau and SF50 were significantly different from the COPD-patients (P < 0.0001). CONCLUSIONS: This study indicates that relaxed expiratory flow-volume curves can be used to assess airflow obstruction in mechanically ventilated patients with COPD. This information can be used to adapt ventilatory settings.

Female↗

PubMed1999

Reference standardization and analytical performance of a liquid homogeneous high-density lipoprotein cholesterol method compared with chemical precipitation method.

BACKGROUND: The use of high-density lipoprotein cholesterol (HDL-C) levels as a risk factor for coronary heart disease necessitates an accurate and precise method for measuring HDL-C. The Centers for Disease Control and Prevention HDL-C reference method (RM) and designated comparison method (DCM) are time-consuming, expensive, and impractical for routine clinical use. We evaluated the Liquid N-geneous (LN-gen) HDL-C assay (Genzyme Diagnostics, Cambridge, Mass) to determine if this homogeneous reagent meets the National Cholesterol Education Program requirements for HDL-C evaluation. DESIGN: Accuracy of the LN-gen HDL-C assay was compared in combination with phosphotungstic acid (PTA) precipitation with DCM HDL-C for normotriglyceridemic serum specimens (triglycerides < 2.0 g/L) and with RM HDL-C for specimens with triglycerides levels > or = 2.0 g/L. SETTING: Genzyme Diagnostics (with RM and DCM assayed by Pacific BioMetrics Inc, Seattle, Wash) and the Lipid Reference Laboratory of the University Hospital Rotterdam, The Netherlands. RESULTS: Linear regression to DCM (n = 90) was (LN-gen = 1.015 DCM + 0.01 g/L, r = 0.993, SE = 0.015 g/L) and (PTA = 1.004 DCM - 0.017 g/L, r = 0.980, SE = 0.025 g/L), with a mean percent bias to DCM of 3.3% and -2.8% for LN-gen and PTA, respectively. The comparison with RM (n = 69) showed an increased mean bias for PTA (-5.8%) as compared with LN-gen (1.5%). The correlation and regression equations were (LN-gen = 1.020 RM - 0.002 g/L, r = 0.985, SE = 0.017 g/L) and (PTA = 1.042 RM - 0.032 g/L, r = 0.984, SE = 0.018 g/L). The precision of LN-gen was confirmed at < 2.1% coefficient of variation, and the total error was calculated to be < or = 7.7% for both normotriglyceride and elevated triglyceride specimens at HDL-C decision points of 0.35 g/L and 0.60 g/L. CONCLUSIONS: The LN-gen HDL-C assay offers a cost-effective convenient method for meeting the 1998 precision, bias, and total error recommendations of the National Cholesterol Education Program.

Blood Specimen Collection↗

PubMed1997

Elastic work of breathing during continuous positive airway pressure in intubated patients with chronic obstructive pulmonary disease (theoretical analysis and experimental validation).

BACKGROUND: Continuous positive airway pressure (CPAP) is known to decrease inspiratory work of breathing in patients with chronic obstructive pulmonary disease (COPD). This effect is primarily attributed to a reduction in inspiratory elastic work of breathing (Wi,el) related to a decrease in intrinsic positive end-expiratory pressure (PEEP). METHODS: The aim of this study is to design a model for computation of Wi,el on the basis of respiratory mechanics in patients with COPD, at various intrinsic PEEP- and CPAP-levels. The model was used to estimate the optimal CPAP-level with respect to the intrinsic PEEP-level in terms of reduction of Wi,el. Calculations of the decrease in Wi,el due to CPAP obtained with the model were compared to changes in Wi,el and total work of breathing (Wi,tot) determined from respiratory measurements in patients with COPD. RESULTS: Model calculations revealed that Wi,el was minimal whenever a CPAP-level equal to the intrinsic PEEP-level was applied. When a CPAP-level exceeding the intrinsic PEEP-level was applied, the reduction in Wi,el was less. Comparing these results to the respiratory measurements, a similar pattern in reduction of Wi,el and Wi,tot was established, although absolute values of the differences were smaller in the experimental data. CONCLUSION: This study indicates that in order to reduce Wi,el in patients with COPD, intrinsic PEEP should be measured and the CPAP-level adjusted to the intrinsic PEEP-level.

Aged↗

PubMed1997

Ventilator-CPAP with the Siemens Servo 900C compared with continuous flow-CPAP in intubated patients: effect on work of breathing.

The effects of continuous positive airway pressure (CPAP) provided by the Siemens Servo 900C ventilator were compared with a continuous flow system (CF-CPAP) in patients weaning from the ventilator. Thirteen patients were studied using both systems at a CPAP level of 0.5 kPa. Additional work of breathing (Wapp) and derived variables were determined in relation to the minute volumes of the patients. The Wapp imposed by the ventilator exceeded the Wapp of CF-CPAP in all patients. The difference in Wapp between ventilator- and CF-CPAP was greater at higher ventilatory needs. The increments in Wapp imposed by the ventilator were positively correlated with the actual end-expiratory pressures (EEP). The EEP increasingly exceeded the preset CPAP level of the ventilator at higher minute volumes. An inspiratory threshold due to a gradient between EEP and preset CPAP greatly increased the Wapp imposed by the ventilator. As this threshold was attributed to the resistance of the PEEP device of the ventilator, it indicates that the additional work related to the expiratory value should be taken into account when the Siemens Servo 900C ventilator is used for weaning purposes.

Adult↗