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Biomedical subjects

G Driessen

Publications and source records attributed to G Driessen.

17 recordsLinked to original sources
PubMed2004

The wider social environment and mental health service use.

OBJECTIVE: Previous studies associating neighbourhood context with mental health service use typically included limited sets of confounders. METHOD: A data set including patients registered in a Case Register and population controls was subjected to multilevel analyses, including neighbourhood exposures and individual level confounders. In addition, days of care consumption of patients was addressed. RESULTS: The association between socioeconomic deprivation and social capital on the one hand and mental health service use rates on the other could be attributed to individual level differences. However, number of days of service consumption was higher in neighbourhoods with more informal social control. In residentially stable neighbourhoods only, socioeconomic deprivation was associated with lower levels of service consumption. CONCLUSION: Higher levels of social control may induce patients to remain in contact with mental health services. Furthermore, higher levels of deprivation in neighbourhoods with little population mobility may result in reduced expectations of recovery and/or increased tolerance.

Adult↗
PubMed2003

Gene flow between arrhenotokous and thelytokous populations of Venturia canescens (Hymenoptera).

In the solitary parasitoid wasp Venturia canescens both arrhenotokously (sexual) and thelytokously (parthenogenetical) reproducing individuals occur sympatrically. We found in the laboratory that thelytokous wasps are able to mate, receive and use sperm of arrhenotokous males. Using nuclear (amplified fragment length polymorphism, virus-like protein) and mitochondrial (restriction fragment length polymorphism) markers, we show the occurrence of gene flow from the arrhenotokous to the thelytokous mode in the field. Our results reinforce the paradox of sex in this species.

Animals↗
PubMed2001

Stroke and mental health care: a record linkage study.

BACKGROUND: Stroke is associated with psychiatric morbidity but little is known about mental health care use in stroke patients. METHOD: A probability record linkage study was conducted linking stroke cases admitted to a teaching hospital serving a catchment area between 1987 and 1995 with records from a psychiatric case register covering the same area. RESULTS: Stroke patients had a more than twofold increased risk of contact with mental health care than individuals in the general population (yearly prevalences of respectively 88 and 39 per 1000; risk ratio 2.24; 95 % CI 2.04-2.45). One-third of all stroke admissions had had mental health care before and more than half had had mental health care after the stroke. In the year of admission for stroke, the probability of receiving mental health care was highest, while in the more remote years the risk was lower. CONCLUSION: Stroke is associated with an increased probability of contact with mental health services. The pattern of mental health care of a stroke patient is different from that of other mental health patients: more episodic and concentrated around the time of admission for stroke.

Adult↗
PubMed2000

Neighbourhood variation in incidence of schizophrenia. Evidence for person-environment interaction.

BACKGROUND: Neighbourhood characteristics may influence the risk of psychosis, independently of their individual-level equivalents. AIMS: To examine these issues in a multi-level model of schizophrenia incidence. METHOD: Cases of schizophrenia, incident between 1986 and 1997, were identified from the Maastricht Mental Health Case Register. A multi-level analysis was conducted to examine the independent effects of individual-level and neighbourhood-level variables in 35 neighbourhoods. RESULTS: Independent of individual-level single and divorced marital status, an effect of the proportion of single persons and proportion of divorced persons in a neighbourhood was apparent (per 1% increase respectively: RR = 1.02; 95% CI 1.00-1.03; and RR = 1.12, 95% CI 1.04-1.21). Single marital status interacted with the neighbourhood proportion of single persons, the effect being stronger in neighbourhoods with fewer single-person households. CONCLUSIONS: The neighbourhood environment modifies the individual risk for schizophrenia. Premorbid vulnerability resulting in single marital status may be more likely to progress to overt disease in an environment with a higher perceived level of social isolation.

Adolescent↗
PubMed1998

Characteristics of early- and late-diagnosed schizophrenia: implications for first-episode studies.

First-episode studies of schizophrenia are being carried out in many places. However, previous work has suggested that only half of the patients with schizophrenia receive the diagnosis in the initial stages of the illness. We examined whether cases of early- and late-diagnosed schizophrenia differed with respect to key sociodemographic characteristics and indicators of service use that might bias first-episode studies. Individuals who (i) presented for the first time between 1983 and 1993 to psychiatric services in a defined urban area with a cumulative mental health case register; and (ii) received a diagnosis of schizophrenia at least once during their mental health career were identified (n = 186). This sample was divided into those who received the diagnosis of schizophrenia for the first time within the first year of service contact (early-diagnosed schizophrenia; EDS), and those who received it for the first time after the first year of service contact (late-diagnosed schizophrenia; LDS). The 10-year incidence of EDS and LDS were 10.4 and 7.0 per 100,000 person-years, respectively. EDS and LDS did not differ in their pattern of association with sex, single marital status and higher levels of neighbourhood socioeconomic deprivation. However, EDS was more incident in the higher age groups, and the level of service use was higher for EDS cases in the first years of contact with mental health services, with LDS cases gradually catching up and exceeding EDS service use later in the illness course. Although differences between EDS and LDS were few, studies of patients with schizophrenia in the 'first' episode are likely to be most representative if patients who receive the diagnosis for the first time after previous episodes of care for non-schizophrenic episodes are also included.

Adult↗
PubMed1998

Shared social environment and psychiatric disorder: a multilevel analysis of individual and ecological effects.

We examined associations, in terms of relative and population-attributable risks, between shared social environment at the neighbourhood level and (1) treated incidence of non-psychotic, non-organic disorders, and (2) subsequent level of service consumption. The multilevel analysis used linked records of all individuals in contact for the first time with any catchment area mental health service for non-psychotic, non-organic disorder over various specified time periods between 1981 and 1995. Socioeconomic indicators of 36 neighbourhoods in the city of Maastricht yielded a multivariately defined neighbourhood deprivation score. There were significant linear trends in the association between level of deprivation and treated incidence, especially in the population under 35 years of age (adjusted rate ratio for linear trend 1.17, 95% confident interval 1.11-1.23), who constituted around half of the patient population. The fraction of the incidence of psychiatric disorder attributable to deprivation was 17.8%. Multilevel analyses of rates of a second cohort, with cases divided according to level of service use over a standardised follow-up of 5 years after first contact with psychiatric services, revealed that the effect of deprivation scores on rates declined with intensity of out-patient service use, but increased with level of in-patient use. Up to 50% of in-patient episodes in this group could be attributed to neighbourhood level of deprivation. The increase in risk conferred by neighbourhood deprivation remained after adjustment for the individual-level equivalent. The findings therefore suggest that elements in the shared social environment influence both incidence and severity of non-psychotic, non-organic disorders, over and above any individual-level effect.

Adolescent↗
PubMed1997

Persons with intellectual disability receiving psychiatric treatment.

Determinants of (1) referral to psychiatric services and (2) the amount of mental health care consumed were analysed in a population of individuals with intellectual disability, using data from a cumulative mental health case register in a defined geographical area. Associations between level of disability, gender, age and social environment on the one hand, and psychiatric referral and service consumption on the other were expressed as odds ratios (ORs). Being older (OR = 1.9; 95% CI = 1.5-2.5), having milder intellectual disability (OR = 1.4; 95% CI = 0.9-2.3) and living alone (OR = 5.8; 95% CI = 2.8-11.9) predicted a higher probability of receiving psychiatric treatment. Living alone (OR = 15.3; 95% CI = 1.7-136.1) was also associated with higher level of mental health service consumption.

Adolescent↗
PubMed1997

Prevalence of long-term mental health care utilization in The Netherlands.

The objective of this study is to estimate the proportion of the population in The Netherlands who receive long-term care for chronic psychiatric problems. The care needs of this population are assessed in terms both of diagnosis and of specific impairments and disabilities. Data from three surveys and two psychiatric case registers in five different areas of The Netherlands provide an estimate of about 3.5 long-term users of psychiatric care per 1000 members of the population aged 20 years or over. One-third of them receive a diagnosis of schizophrenia and related psychotic disorders. Patients most frequently suffer from impairments of mood and affect, volition and drives. Nearly all patients are disabled in their occupational role (work), and about half of the population have problems with self-care and household tasks. Long-term care is to a large extent (40%) provided in hospitals and sheltered accommodation, and the role of day services is relatively insignificant.

Adult↗
PubMed1990

Is the laser Doppler flow signal a measure of microcirculatory cell flux?

To assess oxygen transport as a function of hematocrit, microcirculatory red blood cell flux (microflux) was measured by laser Doppler flowmetry (LDF) in the isolated rat mesentery as well as in cat sartorius muscle. The hematocrit value was varied from 0.5 to 50% while the perfusion pressure ranged from about 2.7 to 13 kPa. Simultaneously macroflux which is the volume flow times the systemic hematocrit value was determined. The curves LDF versus pressure showed saturation at several hematocrit values conveying the impression of autoregulation of microflux. The macroflux curves, on the other hand, curved upward. To clarify whether this discrepancy had a physiological cause, pressure-microflux as well as pressure-macroflux curves were collected in a flow chamber model where regulatory effects are absent. In the model the same discrepancies between micro- and macroflux as in vivo were observed. These discrepancies are explained by maximum values in velocity of about 3 mm/s and in hematocrit value of less than or equal to 20% which the LDF can discern. The limit in velocity is explained by the low pass filter of 12 kHz of the LDF instrument, the limit in hematocrit measurement is probably caused by the light scattering properties of red blood cell suspensions. A complicated combination of effects appears to be responsible for the linearity of the LDF signal versus macroflux at normal hematocrit value.

Animals↗
PubMed1988

A comparative study: perfusion of the micro- and macrocirculation as a function of the hematocrit value.

The fluidity (the inverse of viscosity) of red blood cell (RBC) suspensions in vivo was estimated by means of microcirculatory measurements such as RBC flow velocity, micropressure in arterioles and venules, and vessel geometry, and by means of simultaneous macrocirculatory measurements such as volume flow and perfusion pressure in the whole organ. These in vivo data were compared to in vitro data obtained by viscometry. The experiments were performed on the isolated rat mesentery perfused with a nonaggregating and an aggregating suspension: Human RBC were either suspended in Ringer's or Ficoll 400 solution. The tissue was perfused at various perfusion pressures and hematocrit values. The microcirculatory perfusion was recorded by means of microscopy using a video TV system. Five major results have been identified: First, microfluidities calculated from velocity data in capillaries of the mesenteric membrane were almost identical to the fluidities calculated from macroflow data (volume flow rates and perfusion pressure in the whole organ). Second, in vivo fluidities of both suspensions decrease with increasing hematocrit value but seem to be independent of driving pressure between 4 and 10 kPa. Third, the fluidity of the Ficoll suspensions is lower than the fluidity of the Ringer's suspensions by the same ratio as the continuous phases. Fourth, the in vivo fluidities of the Ringer's suspensions and the Ficoll suspensions for hematocrit values from 20 to 70% and a range of wall shear stresses from 0.6 to 1 Pa were higher than those measured in vitro. Finally, it has been quantified that an increasing number of vessels became stagnant (that is packed by red blood cells) at high hematocrit values, low perfusion pressure, and increased aggregability of RBC.

Animals↗
PubMed1987

Changes in intraconceptus pressure in the rabbit during days 7-10 of pregnancy.

The present study established the magnitude of and temporal changes in the pressure within in situ rabbit conceptuses during early pregnancy. At the 7th, 8th, 9th, or 10th day post coitum (dpc), animals were anesthetized, and the number and dimensions of implantation sites were recorded. Conceptus pressure was measured by the servo-nulling method employing a glass micropipette. The mean number of sites was 6/cornu; spacing appeared normal. Implantation dome volume increased from 7 through 10 dpc: 0.2 +/- 0.03; 0.5 +/- 0.1; 1.6 +/- 0.2, and 2.7 +/- 0.9 cm3, respectively (Day 7 vs. 8, 9 and 10, p less than 0.01). Intraconceptus pressure declined between 7 and 10 dpc: 6.3 +/- 0.4; 5.7 +/- 0.4; 4.5 +/- 0.9, and 3.9 +/- 0.7 mm Hg, respectively (Day 7 vs. 10, p less than 0.05). Pressure fluctuated; the frequency of change in pressure varied between 7 and 8 dpc (4.2 +/- 3.0 to 2.3 +/- 3.5 peaks/min). The amplitude of fluctuation did not vary significantly between 7 and 10 dpc (2.6 +/- 0.3; 0.79 +/- 0.8 mm Hg, respectively). Simultaneous measurement of pressure within the conceptus and within the adjacent uterine lumen indicated that alterations in luminal pressure only occasionally influenced pressure within the conceptus. The decline in conceptus pressure suggests that the uterine wall becomes progressively more compliant as blastocyst cavity/yolk sac fluid accumulates within the conceptus. Conceptus expansion resulting from internal pressure may enhance conceptus-uterine metabolic exchange by facilitating apposition of conceptus-uterine surfaces and by increasing the ratio of conceptus surface to cytoplasmic mass.

Animals↗
PubMed1985

A comparison of micro- and macrocirculation of the isolated rat mesentery preparation.

To allow a comparison of microcirculatory perfusion and whole organ blood flow, pressure-flow curves were established in the isolated rat mesentery preparation at two different hematocrit values (5%; 35 +/- 4%). Besides whole organ volume flow, red blood cell (RBC) flow velocity in capillaries of the mesentery membrane, and RBC-flux in fat tissue along the mesentery arteries as well as in small intestine were simultaneously measured. The arterio-venous pressure difference over the tissue was varied from 20-100 mmHg (2.7-13.3 kPa). It could be shown, that the pressure-flow curves in the mesentery membrane as well as in fat demonstrate autoregulation over a pressure range of 30-70 mmHg (4-9.3 kPa), whereas flow through the small intestine and whole organ responded passively to pressure changes. At constant pressure differences an increase in hematocrit value from about 5% to 35 +/- 4% reduced whole organ blood flow as well as flow velocity in capillaries of the mesentery membrane by 50% over the pressure range applied. It is concluded that in a heterogeneous tissue like the isolated rat mesentery preparation the pressure-flow-relationship in tissue components with a low flow fraction might be disparate from that of the whole organ volume flow. Furthermore, despite differences in the pressure flow relationship for the whole and microcirculation, a changed blood viscosity can be quantified in both circulations.

Adipose Tissue↗